Aluna Everitt
A Novel Approach to Interface Fabrication
Using Laser Cut Optically Clear Perspex
B.Sc. (Hons) Information Technology
for Creative Industries
20/03/2015
Aluna Everitt
SCC.300
2015
“I certify that the material contained in this dissertation is my own work and does not
contain unreferenced or unacknowledged material. I also warrant that the above statement
applies to the implementation of the project and all associated documentation. Regarding
the electronically submitted version of this submitted work, I consent to this being stored
electronically and copied for assessment purposes, including the Department’s use of
plagiarism detection systems in order to check the integrity of assessed work.
I agree to my dissertation being placed in the public domain, with my name explicitly
included as the author of the work.”
Date:
Signed:
Page 1 of 68
Aluna Everitt
SCC.300
2015
ABSTRACT
Increasingly digital fabrication technologies are being adopted in a wide range of settings as
they allow users to rapidly and accurately produce physical designs. Of these technologies,
laser cutters are particularly interesting as they are able to work with a wide range of
materials. This report explores the ways in which the optical properties of clear Perspex
material can be exploited in order to add interactive and visual display capabilities to static
objects. This has potential to support the creation of a new range of wearable technologies,
enclosures, and other designs that do not require expensive and generic circuitry and
electronics. To achieve this, an exploration of material properties was conducted to devise
novel approaches of producing interactive visual displays using a laser cutter. From this,
three fundamental interface elements are produced (i.e. a button, an accelerometer, and a
seven-segment display) and combined into a wearable watch prototype. Finally, a discussion
of design guidelines is presented.
Page 2 of 68
Aluna Everitt
SCC.300
2015
TABLE OF CONTENTS
1. Introduction .......................................................................................................................... 8
1.1 Research Question ............................................................................................................ 8
1.2 Exploring Design Space ................................................................................................... 8
1.3 Outline of Report .............................................................................................................. 9
2. Background ........................................................................................................................ 10
2.1 Related Work.................................................................................................................. 10
2.2 Summary ........................................................................................................................ 13
3. Material Exploration ......................................................................................................... 14
3.1 Visual Exploration.......................................................................................................... 14
3.1.1 Distance Study ......................................................................................................... 14
3.1.2 Angle Study ............................................................................................................. 16
3.2 Interactive Exploration ................................................................................................... 19
3.2.1 Touch Study 1.......................................................................................................... 19
3.2.2 Touch Study 2.......................................................................................................... 22
3.2.3 Touch Study 3.......................................................................................................... 24
3.3 Discussion and Summary ............................................................................................... 25
4. Prototype Elements ............................................................................................................ 26
4.1 Interactive Application Elements ................................................................................... 26
4.1.1 Button ...................................................................................................................... 26
4.1.2 Accelerometer .......................................................................................................... 28
4.2 Interface Application Elements ...................................................................................... 31
4.2.1 Initial Seven-Segment Display (LEDs Around 4 Sides) ......................................... 31
4.2.2 Initial Lighting Observations ................................................................................... 32
4.2.3 Refined Seven-Segment Display (LEDs on Bottom) .............................................. 35
4.3 Discussion and Summary ............................................................................................... 36
5. Application - Watch Prototype ......................................................................................... 38
5.1 LED Enclosure ............................................................................................................... 38
5.2 Interface .......................................................................................................................... 39
5.3 Interactive Button ........................................................................................................... 43
5.4 Final Integration ............................................................................................................. 44
5.5 Discussion and Summary ............................................................................................... 45
Page 3 of 68
Aluna Everitt
SCC.300
2015
6. Design Considerations and Discussion ............................................................................. 47
6.1 Apparatus ....................................................................................................................... 47
6.2 Design and Fabrication of Enclosure ............................................................................. 47
6.3 Design and Fabrication of Display ................................................................................. 48
6.4 Programme Display ........................................................................................................ 49
6.5 Programme Interactive Element ..................................................................................... 50
6.6 Discussion and Summary ............................................................................................... 50
7. Conclusion .......................................................................................................................... 52
7.1 Review of Aims .............................................................................................................. 52
7.2 Limitations ..................................................................................................................... 52
7.3 Future work .................................................................................................................... 53
7.4 Learning Outcomes ........................................................................................................ 53
Bibliography ........................................................................................................................... 54
Appendices .............................................................................................................................. 55
Prototype Elements .............................................................................................................. 55
Seven-Segment Display Chapter .......................................................................................... 56
Watch Chapter ...................................................................................................................... 59
Project Proposal.................................................................................................................... 60
Working Documents Link: http://www.lancaster.ac.uk/ug/everitta
Report Word Count: 13,648
Page 4 of 68
Aluna Everitt
SCC.300
2015
TABLE OF FIGURES
Figure 2.1: Device fabricated through Printed Optics [left]. Device with curved display
produced through PAPILLON [right]………………………………………..………………10
Figure 2.2: 3D printed device fabricated through Savage’s algorithmic process of subtraction
to accommodate manually embedded active components………………………...…………11
Figure 2.3: Ficon tangible 3D display devices with interactive touch capabilities through
table top systems……………………………………………………………………………..12
Figure 3.1: The hardware used in the LDR distance experiment. Black plastic used on LDR
so no light reflects…………………………………………………………………………....15
Figure 3.2: This graph shows the strong negative correlation between the means of the two
variables: light intensity and material length…………………………………………..…….16
Figure 3.3: Arduino, LED and LRD circuit mount for angle study…………………………17
Figure 3.4: This line graph shows the means of expected light intensity readings (based on
the distance formula) and actual light intensity readings for every 10° variation in the
material…………………………………………………………………………………….....18
Figure 3.5: The edges and corner of the material are illuminated brighter than the
surface…………………………………………………………………………………..……18
Figure 3.6: Imperfections can be seen on the laser cut edge of the material - under 30 x
magnifications………………………………………………………………………………..18
Figure 3.7: Arduino, LED and LRD circuit mount for touch study. Finger is applied at 20mm
where the LDR is positioned. Then touch is applied every 20mm along the surface until
120mm distance is reached. No touch is applied at 0mm distance…………….…………….20
Figure 3.8: This line graph shows the average light intensity from the bottom of the material
when touch is applied. Touch distance 0mm represents that no touch is applied and touch
distance 20mm represents when touch is applied directly above the LDR sensor……...……20
Figure 3.9: Volume control device concept using a strip of clear material, an LED light
source, and an LDR sensor……………………………………………………………….…..21
Figure 3.10: Arduino, LED and LRD circuit mount for touch study 2…………………...…22
Figure 3.11: Average light intensity from the first data sample collected. This shows an
irregular pattern that was not expected………………………………………………….……23
Figure 3.12: Line graph visualising the average light intensity from the second data sample
collected. This shows even more irregularity that was not expected…………………….…..23
Figure 3.13: Light intensity decreases as the number of fingers on the surface of the material
increases………………………………………………………………………………...……24
Figure 4.1: Button light switch when no interaction occurs…………………………...……27
Page 5 of 68
Aluna Everitt
SCC.300
2015
Figure 4.2: As pressure on the surface of the material increase LED 2 changes colour from
yellow to pink…………………………………………………………………………….…..28
Figure 4.3: Accelerometer prototype (top not present) with LED and LDR situated
opposite sides of rectangular enclosure………………………………………………………30
Figure 4.4: Comparison of vertical and horizontal displacement based on light intensity….30
Figure 4.5: SSD enclosure (85x120mm) consisting of three layers with LEDs positioned on
all four sides………………………………………………………………………………….31
Figure 4.6: Test 1 with five active LEDs illuminates all of the seven segments and visualises
light path from LED sources proficiently on matt etches…………………………………....32
Figure 4.7: Criss cross pattern etches distribute light rays more consistently compared to flat
matt etches……………………………………………………………………………………33
Figure 4.8: Cuts from test 9 enhances illumination of five segments………………….……33
Figure 4.9: Design and applied SSD with black material insert that isolates each segment of
the display...…………………………………………………………………………….……34
Figure 4.10: SSD displaying digits from 0 to 9 in a range of colours in full ambient
light…………………………………………………………………………………………...34
Figure 4.11: Two layer SSD with LEDs only at the bottom of the enclosure……………….35
Figure 4.12: Single layer SSD design with black inserts and final implementation of an SSD
displaying the figure “4”……………………………………………………………………..36
Figure 4.13: Printed Optics numeric display (a) consisting of embedded air pockets that
reflect light when illuminated (b). The numeric display fabricated through laser cutting (c) in
contrast only uses one layer of material to visualise figures 0-9……………………………..37
Figure 5.1: LED enclosure for watch prototype with chain of seven LEDs situated
inside…………………………………………………………………………………………38
Figure 5.2: Refined display for interactive watch prototype. Consisting of optically clear
Perspex (depth 5mm) and corresponding black material partitions (width:
0.72mm)………………………………………………………………………………...……39
Figure 5.3: Initial watch interface (secured with adhesive to ensure robustness) inserted into
LED enclosure………………………………………………………………………………..40
Figure 5.4: Due to angle restrictions the initial design of the display did not allow light to be
transmitted efficiently to the top sections as shown by numerals 6 and 9…………………...41
Figure 5.5: Refined design of the display enhanced illumination of both figures regardless of
light or dark background and the addition of fascia………………………………………….42
Figure 5.6: Button actuation device consisting of one LED, one LDR, and a strip of optically
clear material…………………………………………………………………………………43
Figure 5.7: Figures 0 to 9 displayed on final watch prototype in full ambient light. The
middle section is no as well illuminated compared the surrounding sections………………..44
Page 6 of 68
Aluna Everitt
SCC.300
2015
Figure 5.8: Figures 0 to 9 displayed with no ambient light present. Each figure is visualised
with greater clarity though the middle segment is still less obvious…………………………44
Figure 5.9: Watch used when no ambient light is present compared to when ambient light is
present……………………………………………………………………………………..…45
Figure 6.1: To display numeric figure “3” LEDs 3, 4, 5, 6, and 7 must be active whilst LEDs
1 and 2 must be inactive…………………………………………………………………..….49
Figure 6.2: Example Arduino processing code for visualising numeric figure “3”……..…..49
Figure 6.3: Word cloud of key phrases and words taken from observations conducting during
open day demonstrations……………………………………………………………….…….51
Figure 7.1: Voronoi diagram isolating each of the eight points with maximum space around
each centre……………………………………………………………………………………53
Page 7 of 68
Aluna Everitt
SCC.300
2015
1. INTRODUCTION
1.1 RESEARCH QUESTION
The majority of interactive interfaces use electronic components situated underneath the
surface of a display (Lin [8], Orchard [11]). Alternatively, interfaces are visualised with
outside projection systems that emit light on top of surfaces (Blöchl [4], Suman [14]). These
methods however are often highly complex and use expensive electronics that are purchased
as separate units. These limitations infringe development and fabrication of interactive
interface devices. Alternative processes, such as 3D printed optical displays, are in
development for simplifying and enhancing the design and fabrication of informative visual
displays. However 3D printed optic displays are often highly complex to implement with
great cost on materials, equipment, and lead time. By extending findings from previous
research in the field of interface fabrication, simple interfaces with limited active components
and low cost materials and fabrication tools can be utilised for a range of applications.
1.2 EXPLORING DESIGN SPACE
The aim of this project is to design and develop an alternative process of developing
interfaces with interactive capabilities. This process will require a minimum number of
electronic components situated on a single side of a Perspex-based display. Using a single
optically clear Perspex sheet for fabrication of displays further simplifies the application
process. This enables new varieties of low cost user interfaces (UI) to be developed.
Transparent display integrated with ubiquitous computing could enable new forms of
wearable technology in future work. Eliminating the need for highly technical electronics and
greater knowledge of electrical implements interfaces could be custom fabricated for a wider
range of users. Developing simplistic processes of fabricating UIs could reduce both cost and
lead time and allow further innovation of wearable and ubiquitous technology.
With the use of laser cutting techniques interactive devices could be fabricated with greater
ease compared to other techniques such as 3D printing. Laser cutters are now more accessible
and cheaper compared to optical 3D printers and use more efficient and simplistic application
methods. Optically clear Perspex material is also much cheaper and highly durable compared
to liquid photopolymer material often used for optical 3D printing. The use of laser cut
Perspex could also reduce the number of active complements needed and decreasing manual
assembly. Three basic varieties of active components could be used to ensure simplistic
implementation. Multicolour light-emitting diodes (RGB LEDs) would provide visualisation
and enable interactivity in conjunction with other components. User interaction would be
enabled through light transmission variations within the material, recorded by a lightdependent resistor (LDR) sensor. For simplistic computations an Arduino processing board
could be used to control any LEDs used to visualise meaningful information based on light
intensity variance. Construction using Perspex material enables low cost yet highly durability
devices to be produced. In addition, a novel process of developing interactive interfaces
enables highly customisable devices to be tailored to an individual’s needs and specifications.
Using a 2D vector based design programme, such as Illustrator, users would be able to
manually draw outlines of a desired interface. The design space would integrate 2D vector
Page 8 of 68
Aluna Everitt
SCC.300
2015
environments for added simplicity. This process would require minimal technical knowledge
needed compared to implementing 3D modelling for printing 3D devices.
1.3 OUTLINE OF REPORT
Using laser cut Perspex material this project aims to demonstrate an enhanced process for the
design and fabrication of novel interfaces with interactive capabilities. This project aims to
present the following contributions:
1. A general approach for using laser cut Perspex prototype elements to display
information and sense user input.
2. Techniques for visualising information using laser cut optically clear material,
including use of etchings and cuts to enhance luminosity of displays.
3. Techniques for sensing user input with laser cut transparent material, a single light
source, and a sensor. This includes touch pressure input with an embedded sensor and
mechanical displacement of light wave guides.
4. Example application that demonstrates how laser cut optically clear material can be
implemented to fabricate wearable transparent interactive displays.
Firstly this report describes and evaluates current processes for rapid prototyping of
interactive interface devices and how current contributions could influence this project.
Secondly, this report explores properties of optically clear Perspex material and how these
can be exploited for visualisation and interaction. Two studies were performed to analyse
visualisation using optically clear Perspex plastic with length and angle as independent
variables. Touch studies were then performed to explore interactive capabilities using light
intensity as an input variable when pressure is applied to surface of the material. The derived
findings were then applied to prototype elements which could be integrated into active
devices that use both interaction and interface visualisation. This demonstrates a wide range
of capabilities enabled by laser cut fabrication which utilises light properties of optically clear
Perspex material. A smart watch prototype was then designed and fabricated based on
principle findings from the exploration and evaluation of pervious individual interaction and
visualisation prototype elements. The main process for designing and fabricating interface
devices with input capabilities is then described and evaluated. Finally a conclusion details a
summation of findings from the project overall, with limitations found, and future
applications of the design and development process.
Page 9 of 68
Aluna Everitt
SCC.300
2015
2. BACKGROUND
The problem statement is to find an efficient process for fabricating novel interfaces with
interactive capabilities. It is proposed low cost rapid prototyping could be enabled by using
laser cut optically clear Perspex material and embedding active components such as a Light
Dependent Resistor (LDR) and Light-Emitting Diode (LED) for interaction and visualisation.
Discussions of relevant systems, approaches and their implications to this project are found
below.
2.1 RELATED WORK
With recent development of optical quality 3D printers there is now an increase in
construction of customisable interfaces with interactive capability. This introduces great
potential for low cost and lead time device fabrication. Wills et al. [16] describe an approach
to 3D printing customizable interactive devices categorised as Printed Optics. Functioning
devices are designed within a digital 3D modelling editor and realized into a single physical
form through optical 3D printing. Active components and optical quality elements are
embedded into the device as part of the fabrication process.
The design and construction of non-flat interactive interfaces is also becoming an emerging
field of research as described by Rümelin et al. [12]. By exploring alternative display forms
which navigate away from traditional flat displays for interactive applications Brockmeyer et
al. [5] elevates the approach taken from Printed Optics to a new domain of interactive
interfaces. The system PAPILLON enables the design of curved display surfaces for
information visualisation and input capabilities through 3D modelling. The interactive device
is then fabricated through 2D optical printing as a single object. Figure 2.1 shows a toy
character with an embedded display visualising a heart shape developed through Printed
Optics (left) and another character with embedded curved display fabricated through
PAPILLON.
Figure 2.1: Device fabricated through Printed Optics [left]. Device with curved display produced
through PAPILLON [right].
The current cost of fabricating such devices however is great in both material cost and
obtaining access to a 3D printer with optical printing capabilities. The majority of the devices
developed are also limited on practical use. They can be categorised predominantly as single
Page 10 of 68
Aluna Everitt
SCC.300
2015
value devices, as described by Mader et al. [9]. Due to multiple materials used and high
number of layers needed to produce just one device elevates lead time and cost of fabricating.
Savage et al. [13] describe a similar approach to designing and developing interactive devices
by embedding optical light tubes within interiors of 3D printed objects. Electronic sensors or
actuation components are manually embedded into the interior of 3D printed objects.
Subtractive processes are implemented through an algorithmic approach to generate space
within 3D models for insertion of active components and electronics. Through manual
insertion electronic sensors or actuation mechanisms are situated within 3D printed objects to
enable interactivity as seen in Figure 2.2.
Figure 2.2: 3D printed device fabricated through Savage’s algorithmic process of subtraction to accommodate
manually embedded active components.
Baudisch et al. [2] demonstrates a tangible system, Lumino, which visualise images when
applied to diffuse illumination table surfaces, such as Microsoft Surface. Glass fiber bundle
blocks are arranged into three-dimensional (3D) structures atop an illuminated surface to
move visual focus to designated locations upon the table surface. Lumino enables custom
optimisation of a tangible visual unpowered and maintenance free system.
Takada et al. [15] presents a similar display system, Ficon, which uses properties of optical
fiber to visualise information on table-top 3D displays. Light from the bottom of a light
emitting surface is conducted up to the top of a tangible 3D display through optically clear
fiber. This allows a user to control visual displays and their position using tangible objects as
seen in Figure 2.3.
The same principle of situating a light source at the bottom of the display will be applied to
this project. However, light sources at the bottom of the device will visualise information on
the outer front face of the display. Through enhanced understanding of material properties
and limitations a fabrication process can be developed to efficiently and clearly enable
informative visualisations using laser cut optically clear material. The refinement of this
process will also ensure information could be viewed in full ambient light (sun light for
example).
Page 11 of 68
Aluna Everitt
SCC.300
2015
Figure 2.3: Ficon tangible 3D display devices with interactive touch capabilities through table top systems.
The fabrication processes for developing interactive interface devices discussed above are
becoming more wide spread and have great potential to change the process of how interactive
user interfaces are manufactured. However, there are limitations of using such design and
implementation processes. Optical fibres or light pipes need to be connected to a sensors of
some form to enable interactive capabilities. With the use of laser cut components there
should no direct contact between the material and sensors. Individual material components
should also be tangible and easily reconstructed for enhanced customisation without the need
to fabricate new structures. As a result lead time and cost of material consumption could be
reduced compared to 3D printing techniques.
One of the main limitations of 3D printing is that there is need for structural support when
fabricating devices with complex geometry. In some cases, device enclosures must be printed
in several parts and manually assembled to avoid structural weakness. As a solution laser
cutting could be applied to construct similar devices from robust material (Perspex sheets)
when using a 2D vector design environment. Although manual assembly would be required,
with careful design decisions the number of components needed would be reduced compared
similar 3D printed devices. Mueller et al. [10] also describe a rapid prototyping system,
LaserOrigami, that produces 3D objects significantly faster compared to traditional 3D
printing techniques using specified laser cutter settings. By stretching and folding the
material, rather than placing joints, the need for manual assembly could be eliminated.
3D printers also vary in quality of application. It is impractical to construct certain shapes
using 3D printers that are less callable of structural support. As a result it becomes unfeasible
to replication devices for open source libraries with complex geometry. Laser cutters are
higher precision manufacturing machines where quality and robustness of fabricated objects
often depends on the material used rather than the apparatus itself. The precision of laser
cutters may vary slightly, but this is often due to quality of maintenance. The LaserPro Spirit
GE, used for this project, is equipped with a sealed carbon-dioxide (CO2) laser that emits
concentrated and invisible laser radiation with a wavelength of 10.6 microns in the infrared
Page 12 of 68
Aluna Everitt
SCC.300
2015
spectrum. As described by Bergman and Stockman [3] the laser is the acronym for Light
Amplification by Stimulated Emission of Radiation. The CO2 laser electrically stimulates the
molecules within a carbon dioxide gas mixture. When focused through a lens, this highlyintense, invisible beam will vaporize dense materials with high precision. Subject to speed
and intensity of the projected beam, the CO2 laser will engrave or cut through Perspex
materials of varied depths.
2.2 SUMMARY
Rapidly prototyping interfaces with interactive capabilities using simplistic tools and
fabrication techniques is becoming increasingly popular. However the majority of current
contributions to this field involve complex implementation processes such as 3D modelling
and electronic assembly. The cost of material and machinery used for fabrication using
optical 3D printers for example is often high and inaccessible to general users. Lead time of
production also increases for more complex implementations. Often devices fabricated using
such approaches are defined as single-value and have little practical use. Laser cutters are
more commonly found within design spaces and require cheaper material (Perspex) which
easily accessible. Lead time is also decreased with laser cutters as often only one layer of
material is needed to produce prototypes. This makes it easier to change elements of current
devices without the need to recreate the whole device again. As a result cost of material and
lead time is reduced. Before design space for fabricate interactive interface devices using a
laser cut material can be explored there must be an understanding of material properties,
limitations, and opportunities.
Page 13 of 68
Aluna Everitt
SCC.300
2015
3. MATERIAL EXPLORATION
In order to understand how laser cut optically clear material can be implemented to fabricate
interactive displays explorations of light properties must first be analysed. Exploring
reflection, refraction, and diffusion fundamentals aids the design and development of
prototype elements that unify to create a fully functioning interactive display. First, visual
exploration studies extend current knowledge for visualising information using laser cut
optically clear material. Secondly, interactive touch studies extend current knowledge for
sensing user input with laser cut transparent material, a single light source, and a sensor.
3.1 VISUAL EXPLORATION
Two exploratory trials were conducted to uncover the effects of Frustrated Total Internal
Reflection (FTIR), as described by Han [6, 7], through laser cut clear Perspex material. The
first study investigated the affects of light transmission through a range of material lengths.
The second trial explored how angled cuts in the material affect light transmission. By
understanding how light transmission varies depending on the two independent variables
(length and angle) a model can be developed which predicts FTIR transmission through the
material.
These studies should aid designers who wish to create laser cut interactive interfaces
themselves, and also provide understanding of how sensors and switches, similar to Wills et
al. [16] Printed Optics, can be designed efficiently but using laser cut material instead.
3.1.1 DISTANCE STUDY
To extend understanding how optical light properties of clear Perspex are affected depending
on scale, a distance study was performed. How is light transmission affected with increased
distance of straight laser cut optically clear material?
Light intensity measured by a light-dependent resistor (LDR) decreases as material length
increases.
LDR readings of light transmitted through different lengths of optically clear Perspex
material are recorded. Lengths range from 10mm up to 200mm, at 10mm intervals (20
samples total). Each sample consists of a 5 second read transmitted every 10 milliseconds
from the Arduino (500 samples total). This time was chosen to analyse variation in the light
intensity over a prolonged period of time to ensure anomalies are minimised.
An Arduino UNO was connected to a NeoPixel light-emitting diode (LED) and an LDR. The
LDR was connected using a 10k resistor. All of these were mounted onto a wooden board to
secure everything in place and enable portability. A serial command was used to trigger the
experiment – input: material length (mm). The Arduino outputted a Comma Separate Values
Page 14 of 68
Aluna Everitt
SCC.300
2015
(CSV) data set to make it easier for R and Excel to process and output graphs. See Figure 3.1
for an image of the hardware implementation. Note how the Perspex material is held in
position using a hole in both the LED and LDR cases. This also ensures secure contact and
less escaped light between the material, LED, and LDR sensor.
LED light source
LDR sensor
Clear Perspex Material
(5mm x 3mm)
Figure 3.1: The hardware used in the LDR distance experiment. Black plastic used on LDR so no light reflects.
A distance and light intensity correlation coefficient was computed to assess the relationship
between light intensity and the Perspex material length. A scatterplot summarises the results
(Figure 3.2). There was a strong negative correlation between the two variables (r = -0.96, n
= 18, p = < 0.001) that indicates light intensity decreased slightly as distance increases. This
decrease is linear which means it can be modelled easily using the data captured:
This experiment was limited to samples ranging up to 200mm; further experiments are
needed to test if the model can be used on much longer lengths of Perspex material (e.g.
1000mm). This formula can be written into an Arduino program to estimate the light intensity
drop when creating prototypes with different material lengths such as, a bracelet. The next
step in the research is to perform a similar experiment but with different angles.
Page 15 of 68
Aluna Everitt
SCC.300
2015
Figure 3.2: This graph shows the strong negative correlation between the means of the two variables:
light intensity and material length.
3.1.2 ANGLE STUDY
To enhance the scope of fabricating interface using laser cut material, light properties of
transparent Perspex with a range of angle cuts was explored. What are the effects on light
transmission with angle of optically clear material variance?
Light intensity decreases as the angle of the material increases. Acute angles will allow more
light transmission whereas obtuse angles will transmit less light.
Record LDR readings for light transmitted through clear Perspex material, where each piece
of material has a different angle. These angles will range from 10° degrees up to 170°
degrees, at 10° degrees intervals (17 samples total). Each sample consists of the same 5
second read transmitted every 10 milliseconds from the Arduino (500 sample total). Each
material has a 3 mm inner corner radius and a length that allowed fit into the cases as
appropriate. The distance model was used to approximate the expected LDR reading for each
length of material.
Page 16 of 68
Aluna Everitt
SCC.300
2015
The hardware implementation was very similar to that of the distance experiment (Figure
3.3). The LED cases could be removed from the Arduino mount to accommodate the tighter
angles of material. The serial command that was used to trigger the experiment used two
input independent variables: angle of material (degrees) and material length (mm).
LED light source
LDR sensor
Clear Perspex Material
(5mm x 3mm)
at 50° angle
Figure 3.3: Arduino, LED and LRD circuit mount for angle study.
A line graph (Figure 3.4) shows both the expected LDR readings (based on material length
formula derived from the distance study) and the actual LDR readings from the angle
experiment. The difference between these lines represents the impact of the angle on the LDR
intensity. From this it can be observed that smaller angles have less impact than larger angles.
The difference is more significant for obtuse angles over 130°.
Page 17 of 68
Aluna Everitt
SCC.300
2015
Figure 3.4: This line graph shows the means of expected light intensity readings
(based on the distance formula) and actual light intensity readings for every 10° variation in the material.
Two correlation coefficients were computed to assess the relationships between (a) length
and light intensity (r =-0.92, n=15, p=<0.001) and (b) the angle and light intensity (r =-0.65,
n=15, p=<0.005). From the statistics it is evident that there is stronger negative correlation in
the relationship between length and light intensity compared to that of angle and light
intensity. This means that considering length has more impact in light transmission compared
to considering angle.
From the observations taken during the experiment it was clear that more light was escaping
through the laser cut edges and corner angle of the material than the polished surface, as
shown in Figure 3.5. This is most likely due to laser induced damage where the material is
cut. These imperfections can be seen in the microscopic image in Figure 3.6.
Figure 3.6:
Imperfections can be
seen on the laser
cut edge of the
material - under 30 x
magnifications.
Figure 3.5: The edges and corner of the material are
illuminated brighter than the surface.
Page 18 of 68
Aluna Everitt
SCC.300
2015
3.2 INTERACTIVE EXPLORATION
Three touch studies were conducted to evaluate interactive properties of optically clear
Perspex when light is directed throughout its core. A range of finger based input variables
were tested taking into consideration the phenomena of Frustrated Total Internal Reflection
(FTIR). Based on the findings from these touch studies a larger design space could be
explored for implementing interactive prototype elements.
3.2.1 TOUCH STUDY 1
To enable interactive capabilities of laser cut interfaces, this study demonstrates how
transparent Perspex can be used to detect touch. Can finger position on the surface of laser
cut optically clear material be detected depending on light intensity changes?
When touch on the surface of the material is closer to the LDR the variation in light intensity
is greater.
Take LDR reading of light transmission when a finger (15mm width) is applied to specific
points on the surface of the material. Material length used 130mm. Touch will be applied
every 20mm along the surface of the material. Underneath the longer horizontal piece there
will be a shorter piece of material that is 20mm in height. This shorter piece of material will
be placed 20mm away from the end of the material and will also be connected to an LDR
sensor. Using FTIR the light will travel down through the shorter piece of material when
touch is applied to the surface of the material. The first recording will be at 0mm where no
touch is applied at all to the surface of the material. Then light intensity will be recorded
when the finger is applied 20mm away from that LDR position (40mm on length of material
surface), this is repeater every 20mm until finger touch is applied at 120mm on the surface
material.
The hardware implementation was very similar to that of the distance and angle experiments.
However the LDR sensor was placed at the bottom of the smaller vertical piece of material to
take reading of light transmission (see Figure 3.7). The serial command that was used to
trigger the experiment used two input independent variables: horizontal material length (mm)
and touch distance away from the original LDR position 20mm away from the end of the
surface material.
Page 19 of 68
Aluna Everitt
SCC.300
2015
Clear Perspex Material
(5x3x130mm)
LDR
sensor
Material
length 20mm
LED
light source
Figure 3.7: Arduino, LED and LRD circuit mount for touch study.
Finger is applied at 20mm where the LDR is positioned. Then touch is applied every 20mm along
the surface until 120mm distance is reached. No touch is applied at 0mm distance.
Figure 3.8 illustrates the average light intensity passing though the material when touch is
applied. Touch distance 0mm represents the reading when no touch is applied. Touch
distance 20mm represents when the finger is directly below the LDR sensor. This is when the
greatest light intensity change occurs as the finger is applied directly above the LDR. It peaks
dramatically compared to all of the other readings and this is due to the light rays reflecting
from the finger down towards the LDR instead of passing horizontally though material.
Figure 3.8: This line graph shows the average light intensity from the bottom of the material when touch is
applied. Touch distance 0mm represents that no touch is applied and touch distance 20mm represents when
touch is applied directly above the LDR sensor.
Page 20 of 68
Aluna Everitt
SCC.300
2015
Considering that 0mm touch distance represents no touch applied it is evident that there is a
slight decrease in light intensity when the finger is applied further along the surface of the
material, after the initial 20mm mark. This means that some of the light reflecting downwards
into the LDR is lost/absorbed when single finger touch occurs away from the LDR.
From these results two observations can be made:
1. When finger touch is applied directly above the LDR sensor more light rays travel
down through the shorter vertical Perspex material that is connected to the LDR
sensor, this FTIR phenomenon increase the light intensity LDR reading.
2. When comparing no touch with touch further away from the LDR there is a slight
decrease in light intensity. This could be due to the light rays being disturbed earlier
when reflecting through the material and thus more rays escape before reaching the
LDR.
From the results found during the touch study it was found that interactivity can be achieved
using light intensity as a variable input. A simplistic button action can be developed where
the user could activate a command by applying pressure touch to a particular part of the
material surface where the LDR is located. This interactivity is achieved though FTIR
variations. Light transmission changes can also occur when touch is applied at further
distances away from the LDR a simple two state variable interactive interface can be
developed. A simple control system (see Figure 3.9) could be created, where light
transmission increase is detected using the LDR and the volume of speakers can also
increase. When relatively low light intensity decrease is recorded then the volume is turned
down.
Human finger
Clear material
LED
light source
LDR underneath
clear material
Speaker volume increases
when LDR reading is high and
decreases when LDR
reading is low
Figure 3.9: Volume control device concept using a strip of clear material, an LED light source,
and an LDR sensor.
Page 21 of 68
Aluna Everitt
SCC.300
2015
3.2.2 TOUCH STUDY 2
To enhance the range of user input capabilities, a study explores possible correlation between
position of a finger and the resulting light intensity. Can finger touch position be detected
depending on light intensity changes when an LDR is placed directly opposite an LED?
When touch is applied on the surface of the material close to the LDR the variation in light
intensity is greater.
The LDR reading of light transmission will be taken when a finger (15mm width) is applied
to specific points on the surface of the material. Material length used 130mm. Touch will be
applied every 10mm along the surface of the material. The LDR sensor will be located
directly opposite the LED light source and connected to the material (5 x 3 x 130mm in
dimensions). Using FTIR the light will travel through the material and when touch is applied
to the surface light rays reflecting within the material will be disrupted and more light should
escape through the material before reaching the LDR sensor. The first recording where touch
is applied will be at 10mm away from the LDR. This is repeated at intervals of 10mm until
the touch applied is 120mm away from the LDR (12 samples total).
The hardware implementation was very similar to that of the distance and angle experiments
where the LDR sensor was placed directly opposite the LED on the other end of the material
as seen in Figure 3.10. The serial command that was used to trigger the experiment used two
input independent variables: horizontal material length (mm) and touch distance away from
the LDR starting at 10mm on the material surface.
LDR
sensor
Clear Perspex Material
(5x3x130mm)
LED
light source
Figure 3.10: Arduino, LED and LRD circuit mount for touch study 2.
Page 22 of 68
Aluna Everitt
SCC.300
2015
Figure 3.11 shows a decrease in light intensity up until touch is applied 50mm away from the
LDR on the surface of the material. Then there is a high increase in light transmission in
when touch is applied between 60mm and 70mm, followed by another decrease at 80mm
distance. This result was unexpected and another sample of data was collected when
repeating the experiment to ensure these results were valid.
Figure 3.11: Average light intensity from the first data sample collected.
This shows an irregular pattern that was not expected.
Figure 3.12 shows the second data sample has even greater disparity. Overall the data has
high variance between samples and there is no consistent relationship found between the
touching distance ad light intensity when one finger is applied on a particular point on the
surface of the material when the LDR is positioned directly opposite the LED light source.
Figure 3.12: Line graph visualising the average light intensity from the second data sample collected.
This shows even more irregularity that was not expected.
Page 23 of 68
Aluna Everitt
SCC.300
2015
3.2.3 TOUCH STUDY 3
This study explores if laser cut material could enable multi-touch interaction based on light
intensity changes corresponding to number of fingers applied to the surface. Does applying
pressure with multiple fingers effect light intensity when the LDR is placed directly opposite
the LED?
When touch is applied with more than one finger on the surface of the material light intensity
decreases.
Take LDR reading of light transmission when a finger (15mm width) is applied on the
surface of the material. Material length used 130mm. Record light intensity when additional
fingers are touching the surface one at a time until 10 samples are collected.
The hardware implementation was very similar to that of “touch study 2” experiment where
the LDR sensor was placed directly opposite the LED on the other end of the material as seen
in Figure 3.10. Multiple fingers were applied to the surface of the material and light intensity
was recorded for sets of fingers in close proximity. Starting from 1 finger and incrementing
until 10 fingers were applied to the surface of the material. The serial command that was used
to trigger the experiment used two input independent variables: horizontal material length
(mm) and number of fingers applied on the material surface.
As the number of fingers on the surface of material increase, light intensity within the
material decreases (see Figure 3.13). The application of a large number of fingers on the
surface of the material can be used as a form of user input.
Figure 3.13: Light intensity decreases as the number of fingers on the surface of the material increases.
Page 24 of 68
Aluna Everitt
SCC.300
2015
3.3 DISCUSSION AND SUMMARY
This chapter considers visual and interactive explorations of optically clear material to enable
efficient fabrication techniques for prototyping interactive interfaces. In terms of visual
capabilities, a linear model of light transmission was derived through various lengths of
material. This showed that light intensity through the material was constant, even with
ambient light present, yet varied with material length. In terms of interactivity, touch could be
detected using an LDR to read any changes of light intensity exploiting FTIR variance. To
apply scope to the explorations some parameters were not explored such as width of material
impact on light intensity. Those selected for exploration had greater impact on devices
fabricated for this project.
To increase validation of studies performed large sample sizes (n=500) were used to
minimise anomalies. Independent variables were sampled in fixed steps such as length
(between 10mm to 200mm, every 10mm) and angle (between 10° to 170°, every 10°) as it
would be impractical to laser cut every possible angle. Although observations have not been
obtained beyond these ranges, additional findings are expected to follow the same model. In
terms of interaction, only finger based interaction was explored. This limits the exploration of
alternative input possibilities such as use of stylus pens. However given prevalence of touch
based interaction this method is justified.
In future studies an extended range of material lengths and widths should be tested to gain
enhanced understanding of impact on larger scale implementations. In addition, alternative
methods of input interaction should also be explored to further explore possibilities of
expanding the design space for prototyping interactive displays.
In conclusion the work in this chapter enables the design and fabrication of interface
prototypes such as switches, sliders, and touch detection. These can be a range of sizes and
shapes as explored through the studies. In the next chapter this is built on by creating
fundamental prototype elements such as switches and displays. This enables the construction
of a prototype that combines all of these elements.
Page 25 of 68
Aluna Everitt
SCC.300
2015
4. PROTOTYPE ELEMENTS
This chapter details meaningful uses of properties found from the previous light explorations.
Single systems for interaction and information visualisation are implemented for a range of
applications. These single systems can later be combined to produce a fully functioning
interfaces prototype with interactive capabilities.
4.1 INTERACTIVE APPLICATION ELEMENTS
Developing simple user input prototype elements demonstrates principles found in the
exploratory interactive studies. Simple interactive prototype mechanisms can later be
implemented in a variety of scenarios. The first sub-section of the chapter focuses on
application examples demonstrating how laser cut device components could enable user
interaction through displacement of light. The second sub section expands on how laser cut
devices could be used to display meaningful information without the need of electronics
situated behind the interface or even projected atop the surface.
Prototype elements produced for this chapter:



Button light switch
Accelerometer
Seven-Segment Display
o Light sources situated around four sides of display.
o Light sources only situated on one side of display.
4.1.1 BUTTON
The button element (light switch) was based on interactivity principles discovered from three
touch studies performed. It was found that optical sensing could be achieved through push
and pressure application to the surface of the material. By embedding optically clear material
into an enclosure fitted with a separate light source, a light switch mechanises was produced.
The principle input variable for this device was based on light transmission displacement
recorded by a standard light-dependent resistor (LDR). The light switch device would be
separated into two elements. First, clear Perspex material with light transmitted through it
(LED 1) would be used as an actuator that senses user input when pressure is applied to the
surface. This would be achieved through Frustrated Total Internal Reflection (FTIR)
phenomena and recorded using an LDR sensor positioned below the material. Secondly, a
light source (LED 2) would be activated when light intensity readings (LDR with a 10k
resistor) reach a specified threshold. This threshold is calculated by sampling light intensity
behaviour when pressure is present on the surface of the material. The colour of LED 2
would change depending on the amount of level of pressure applied to the surface.
Page 26 of 68
Aluna Everitt
SCC.300
2015
Apparatus used:
1. 2x LEDs - first for clear material and second as output to visualise interactivity.
2. 1x LDR - sensing light intensity through material.
3. 1x Arduino Uno - computing interactivity variable.
An enclosure was first fabricated by laser cutting three pieces of black material (dimensions:
180x25x3mm). Each of the three layers had specific cavities cut to accommodate three
electronic apparatus need for the device. The bottom layer had three cavities to house both
LEDs and LDR that would be situated in the two layers above. The middle layer also had
three similar cavities. The main cavity of the middle layer (dimensions: 3x5x3mm) was for
the LDR sensor. It ensured the LDR would be situated directly below the clear material that
would be placed within a frame above. Finally, the top layer consisted of a cavity frame to fit
a piece of optically clear Perspex (dimensions: 110x5x3mm) with a slot to fit LED 1 on one
side, 50mm away from the LDR cavity. The other slot is cut into the top layer 35mm away
from the interactive elements of the device (dimensions: 5x5x3mm) where LED 2 is situated
without impacting the light intensity reading from the LDR. The use of LED 2 is
predominantly to visually demonstrate user input capabilities. The enclosure was assembled
using four nuts and bolts, one situated at each corner of the rectangular enclosure.
Once all three electronic components were soldered and placed within the enclosure into their
designated cavities an optically clear piece of material was cut and placed within the frame of
the top layer, with corresponding dimensions to the frame (110x5x3mm). This material piece
could be taken out of the enclosure with ease in order to deactivate the device. Figure 4.1
shows the fabricated button light switch.
LDR sensor under
transparent
material
LED 1
light source
Clear Perspex Material
(110x5x3mm)
LED 2
visualising interactivity
Figure 4.1: Button light switch when no interaction occurs.
Based on the findings from the previous touch studies, light intensity through the material
should increase when enough pressure is applied to the surface at a specific point when
ambient light is present. The LDR sensor situated directly below the point of contact records
light intensity changes when pressure is applied. When pressure was applied directly above
the LDR, a 5 second read transmitted every 10 milliseconds (500 sample total) was averaged
and used as a threshold for activating LED 2. Subsequently, the same process was applied
Page 27 of 68
Aluna Everitt
SCC.300
2015
when finger pressure on the surface of the material was relatively light or when the finger
was hovering over the surface. The average reading from this second sample was used as the
second threshold for activating a different colour light from LED 2 when light intensity
decreased.
A basic light switch device was designed and fabricated based upon interactive principle
discovered during the exploratory touch studies. A simplistic enclosure was designed where
clear Perspex material could be placed into a fitted frame. Finger pressure of the user was
treated as an independent variable. Light intensity transmission was therefore treated as a
dependant variable and used as an input measurement for light switch actuation. User input
was achieved by sensing light intensity change caused by FTIR. Using a low-cost LDR
discretely situated within the enclosure three threshold sates were used as input variables to
activate a light source (LED 2). Hard finger pressure applied to the surface defines high state
and LED 2 emits pink light. When light finger pressure is applied low state (decrease in light
intensity) is achieved and LED emits yellow light (Figure 4.2). When no finger is present, the
device is set to no state and LED 2 is deactivated.
Low State
Light Intensity
Decrease
High State
Light Intensity
Increase
Figure 4.2: As pressure on the surface of the material increase LED 2 changes colour from yellow to pink.
It was found that these three states could only be achieved when enough ambient light is
present in the test environment. When no ambient light is present only two states could be
achieved. When any form of pressure is applied to material surface at a point directly above
the LDR, light rays are directed towards the receiver hence only allowing for light intensity
increase.
4.1.2 ACCELEROMETER
A simplistic accelerometer was developed which was actuated through displacement of light
guides present within a thin strip of material that was situated in a small black enclosure to
avoid ambient light affecting any readings. This device monitors movement displacement
from the outside environment. Further displacement is also caused by effects of gravity due
to the strip drooping slightly downwards.
Page 28 of 68
Aluna Everitt
SCC.300
2015
A case enclosure would house a small strip of optically clear material with a wider, heavier
section cut on the end in order to enhance the effects of outside motion. A light source would
be positioned at one end of the enclosure in a cavity to illuminate the clear strip of material
within. A light-dependent resistor (LDR) should be positioned at the other end of the case. As
the light-emitting diode (LED) rays travel through the thin material any outside displacement
should affect the thin, clear strip. As a result it should move away from the LDR, hence
causing a change in light intensity reading.
Apparatus:
1. 1x LED
2. 1x LDR
3. 1x Arduino Uno
The fabrication of the accelerometer is separated into two sections. First, a small rectangular
enclosure was cut from 3mm black Perspex material (dimensions inside: 93x19x19mm). Two
openings were cut at each end of the enclosure. The first opening (dimensions: 5x5mm) for
situating an LED. The second opening at the other end of the enclosure (dimensions:
5x3.5mm) was cut to accommodate a standard LDR. This rectangular box enclosure was
assembled in place with acrylic adhesive. The top section was detachable to enable the
placement of the clear material strip. Six vertical sections were etched parallel to each other
along the inside walls of the case (dimensions: 4x19x0.5mm). These were used as
placeholders for a smaller piece of material that will hold the optically clear strip of Perspex.
The small piece of black material was cut separately (dimensions: 20x19x3mm) with an
incision measuring 4mm in width and 1mm in height, directly at the centre. This “strip holder
piece” was placed securely inside of the enclosure by sliding it into one of the etched sections
located within the case. Sensitivity of the accelerometer could be changed by positioning the
“place holder” piece closure to the LDR.
Secondly, an optically clear strip was cut from 3mm material. The optimal width of cut to
ensure flexibility yet durability for the strip was 0.72mm with the length of 94mm. A larger
section was cut on the strip, 9.9mm away from the end (dimensions: 5x3mm) in order to
enhance the effect of displacement outside. Figure 4.3 shows the accelerometer produced
from laser cut material and two active components.
Page 29 of 68
Aluna Everitt
LED
light source
SCC.300
Material Strip Holder with incision
(20x19x3mm)
2015
Cushion
LDR
sensor
Clear Perspex Material
(94x3x0.72mm)
Figure 4.3: Accelerometer prototype (top not present) with LED and LDR situated
opposite sides of rectangular enclosure.
In order to identify any displacement characterisation the independent variable for this study
was based on velocity. Firstly the independent variable incorporated vertical velocity by
repeatedly shaking the device up and down. Light intensity was considered as the dependant
variable and readings were recoded using an LDR for a period of 1.7 seconds. The
independent variable changed to incorporate horizontal movement and the device was shaken
from left to right on the horizontal axis. Light intensity readings were recorded for 1.7
seconds. Figure 4.4 illustrates the comparison between horizontal and vertical displacement.
Figure 4.4: Comparison of vertical and horizontal displacement based on light intensity.
The local maxima of light intensity for vertical movement is much higher (200±10 LDR
reading) compared to that of movement performed on the horizontal axis (170±10 LDR
reading). The device worked relatively well when constant displacement on a specific axis
occurred. However, it is difficult to observe the exact behaviour of the material strip as the
active components are enclosed within the case. Performance can enhanced if material length
was shorter as more light would reach the LDR. Due to high variance in readings throughout
prolonged periods of time and lack of touch based interactivity the accelerometer would not
be featured in the final application.
Page 30 of 68
Aluna Everitt
SCC.300
2015
4.2 INTERFACE APPLICATION ELEMENTS
Seven-Segment Displays (SSD) visualise meaningful information through individual state
transformations of single characters or numerals. Two SSDs were designed and fabricated
using laser cut Perspex material. The initial SSD, with seven LEDs around all four sides, was
produced to explore light guide manipulation. The initial display illuminated isolated
segments in a specified order that mimicked state changes of a conventional SSD. After an
efficient design approach was established, a second SSD was implemented where light
sources were situated only at the bottom of the display. This chapter details the process of
design and fabrication for both displays, including discussion of design decisions made to
develop an efficient approach to illuminating various states of an SSD.
4.2.1 INITIAL SEVEN-SEGMENT DISPLAY (LEDS AROUND 4 SIDES)
The initial SSD was developed in two stages. First, a 2D vector outline of an enclosure was
designed in Illustrator to specific measurements of 85x120x9mm (see Appendix Figure 3).
Three layers of laser cut black Perspex plastic (3mm depth) were combined and assembled
using 3mm nuts and bolts. The top layer of material was a frame where the clear Perspex
display could be placed. Seven LEDs were chained together and interlinked within seven
slots of the enclosure. Each LED was specifically positioned within the frame to illuminate
only one designated segment (see Figure 4.5). The frame was designed to hold material
within the measurements of 65x100mm. Secondly, a number of displays were designed and
laser cut out of clear material with depth range from 3mm to 5mm. The observations from the
range of laser cut and etched displays can be found below.
Transparent
display should be
situated within
the frame
(65x100mm)
Each LED
light source
with a number
allocated to it
Figure 4.5: SSD enclosure (85x120mm) consisting of three layers with LEDs positioned on all four sides.
Page 31 of 68
Aluna Everitt
SCC.300
2015
4.2.2 INITIAL LIGHTING OBSERVATIONS
A range of SSD designs was explored and eight test cases were implemented in order to
determine a proficient solution to illuminating isolated segments of an SSD (for full recorded
observations see Appendix Table 1). A range of etching styles and depths was also explored
to find an efficient approach for enhanced illumination. In an attempt to manipulate light
guides a range of cuts with varied widths and positions were also tested. Each segment was
uniform in shape (elongated hexagons) and relative to each other in size. In order to observe
light distribution effects an individual etches, each segment was scaled to maximum size of
12x37mm in the first four tests. All segments of the display were illuminated even when
black tape was applied to the top of active LEDs in an attempt to eliminate any ambient light
emitted. Full matt etch are coarse and do not distribute light rays evenly throughout a whole
segment. Matt etches reveal the direct path of light from a light source as seen in Figure 4.6.
Direct light
path from LED
light source is
clearly visible
on matt etches
Figure 4.6: Test 1 with five active LEDs illuminates all of the seven segments and visualises light path from LED
sources proficiently on matt etches.
For light rays to be distributed more consistently throughout each segment a crisscross
pattern was designed to defuse refraction. Figure 4.7 shows the initial 2D vector design of the
pattern and result.
Page 32 of 68
Aluna Everitt
SCC.300
2015
2D vector design
LED light rays
evenly distributed
within a segment
Figure 4.7: Criss cross pattern etches distribute light rays more consistently compared to flat matt etches.
To enhance luminosity of each active segment a range of cuts were made on the surface of
the display and impact of illumination for each segment was observed. Diagonal cuts (0.1mm
width) correlating to each segment efficiently brightened etched areas closest to the cut as
seen in Figure 4.8. This was due to light refracting within air gaps and this intensified the
effect of emitted light rays. Real life observations show the right segments illuminated
brighter compared to the middle section.
Cuts made in
close
proximity to
segments
enhance their
brightness
Figure 4.8: Cuts from test 9 enhances illumination of five segments.
In order to isolate light emitted from an LED to a single designated segment, black insertions
were designed and placed into the display. The width of cuts was increased to 1mm width
and black material (3mm depth) was cut corresponding to cavities in the transparent display.
The black material inserts (1mm width) isolated each of the seven sections of the SSD and
occluded light rays reaching inactive segments. Several refinements were made to the
position and design of the black inserts until a proficient implementation was found. As seen
in Figure 4.9 black inserts enable each segment to be illuminated individually without light
effective adjacent segments.
Page 33 of 68
Aluna Everitt
SCC.300
2D vector design
2015
Display produced
A singular
black insert
isolates each
segment to
reduce
number of
components
needed for
assembly
Figure 4.9: Design and applied SSD with black material insert that isolates each segment of the display.
Black inserts occlude light rays from reaching inactive segments. Further refinements to the
design of cuts enabled clear interchangeable states of numerals to be displayed in various
colours when ambient light is present as seen in Figure 4.10.
Figure 4.10: SSD displaying digits from 0 to 9 in a range of colours in full ambient light.
The display is able to visualise each of the 128 states of an SSD with LEDs situated around
all four sides of the enclosure. To refine the design further LEDs where positioned only at the
bottom of the display. A second SSD prototype was fabricated, using the same design
approach, where seven LEDs were situated only on the bottom of the frame.
Page 34 of 68
Aluna Everitt
SCC.300
2015
4.2.3 REFINED SEVEN-SEGMENT DISPLAY (LEDS ON BOTTOM)
Much like the initial SSD, the second display consisted of an enclosure made from three
layers of black Perspex material (depth 3mm) with the top layer acting as a frame for a clear
display. The prototype was scaled up to a larger size (120x140x9mm) for the enclosure, with
frame area 100x120x3mm. Seven LEDs (9mm width each) were soldered to create a
sequential chain (length 80mm). Once the LEDs where set up within the enclosure, the design
of the initial SSD layout was readjusted to accommodate the new LED alignment.
The first redesign of the SSD reflected upon Wills et al. [16] implementation of digital
signage, where ten layers are used for visualising individual numeric figures. For the refined
SSD two layers of material created an interface that visualised single figures with light
sources directly underneath the display. The bottom layer consisted of clear material (5mm
depth) divided into seven individual light tubes, one for each segment. Each light tube was
situated directly above a designated LED that emitted light rays to a corresponding segment.
The light tubes were extended below a selected etched segment. Large cuts were made
directly below the etched pattern to intensify luminosity of etched segment above. The top
layer was implemented by applying a similar design as the initial SSD. Figure 4.11 shows the
two layers SSD with light sources below the enclosure. This implementation provided low
luminosity and could be refined further by reducing the number of layers.
Top layer etched
segment
illuminated
from light tube
situated
underneath
Bottom layer
light tube
emitting light to
top segment
Chain of seven
LEDs
Figure 4.11: Two layer SSD with LEDs only at the bottom of the enclosure.
Page 35 of 68
Aluna Everitt
SCC.300
2015
A refined version of the initial SSD display was implemented with a single layer of material
(5mm depth) and corresponding black inserts (5mm depth). Elongation of black inserts
ensured light emitted from adjacent LEDs did not affect inactive segments (see Figure4.12).
In order to fully partition each segment and ensure no light escaped to inactive segments, the
display was divided into separate five sections. As this prototype used a frame based
enclosure the prototype could stand vertically without any need for adhesive.
Two black inserts partition the display
into five sections
Figure 4.12: Single layer SSD design with black inserts and final implementation of
an SSD displaying the figure “4”.
4.3 DISCUSSION AND SUMMARY
This section of the report evaluates all prototype elements produced and their purpose for the
next stage of application. A breakdown of the design and fabrication process for developing
successful SSD displays with light sources situated only on one side can also be found below.
Breakdown of design and fabrication process for developing an efficient SSD display:
1.
2.
3.
4.
Design simple enclosure in proportion to length of LED strip.
Laser cut black Perspex material to corresponding design.
Assemble and insert LED strip.
Design seven-segment display with enough space between each segment to insert
1mm width black material.
o Add lines (1mm width) to partition each segment of the display.
5. Laser cut setting for most effective result for etches and cuts varies depending on
material depth please see Appendix Table 1 for details for 5mm depth material.
6. Once the display is cut and etched corresponding cuts must be made to black material
of the same depth and inserted into the display where appropriate.
Page 36 of 68
Aluna Everitt
SCC.300
2015
With influence from the initial SSD design, black inserts are redesigned to accommodate
light sources that are situated underneath the display. These interfaces are highly robust and
could be submerged in water. Using only one layer of material eliminates the need for
electronics to be present in the actual interface.
Wills et al. [16] implemented a similar display system using 3D printed rectangular blocks
with air pockets. Wills et al. [16] developed a nixie tube style numeric display consisting of
numeric figures embedded into ten 3D printed sheets. The SSD interface developed for this
project uses one layer of material produce the same outcome with a light source enabling
illumination of numeric digits. Figure 4.13 shows a comparison between both displays
Figure 4.13: Printed Optics numeric display (a) consisting of embedded air pockets that reflect light when
illuminated (b). The numeric display fabricated through laser cutting (c) in contrast only uses one layer of
material to visualise figures 0-9.
Fabricating interfaces from a single material enables new kinds of cheaper wearable
technology to be utilised. The next stage is to apply this design and fabrication process on a
smaller scale in order to prove it can be implemented as a transformative process. Using the
example of a smart watch ensures the SSD design could be used effectively to display
meaningful information on a transparent interface on a smaller scale in a novel manner.
In term of interaction, light intensity readings were affected by presence of ambient light
within the test environment. If ambient light from the environment was to constantly change
the configuration of the device must be monitored and reset to accommodate the ambient
light changes. This may decrease accuracy of the device. Nevertheless an algorithm could be
computed that eliminates any form of ambient light. Alternatively, an algorithm could
monitor changes in the environment (using a separate LDR) and notify a user when ambient
light displacement occurs and recalculate threshold levels when pressure is applied and not
applied to material surface. This could be done also by adding a compositor to the LDR
circuit.
In conclusion, the work in this chapter demonstrates prototype elements that can be fabricated
as single systems. In order to create a fully functioning prototype both interactive and visual
elements must be integrated. In the next chapter this is built on by creating unified prototype
interactive watch that is activated through user input to visualise current time.
Page 37 of 68
Aluna Everitt
SCC.300
2015
5. APPLICATION - WATCH PROTOTYPE
This chapter details the design and production of a watch device as a final proof of concept
based on the alternative fabrication process developed from preceding chapters. The final
prototype integrates application elements from previous studies and applies it in a ubiquitous
context to develop a wearable device. This final prototype incorporates the interactive
properties of clear Perspex material discovered from the touch studies and button light
switch. An interface was conceptualised and developed based on the design and fabrication
process used to create an SSD interface.
The proposed smart watch should be small in scale and display current time using individual
numeric figures sequentially on a single later of optically clear material. An interactive button
would be used to activate the display. When a user applies sufficient level of pressure to the
surface of the material a change in light intensity, measured by a light-dependent resistor
(LDR), will occur. This will be used as an actuation command to display current time on the
interface.
5.1 LED ENCLOSURE
First, a chain of seven RGB Light-emitting diodes (LEDs) was soldered together. Each LED
(dimensions: 5x5mm) was designated to illuminating one segment of the SSD. The total
length of the LED chain was 70mm. In future work much smaller surface mount RGB LEDs
(dimensions: 3x3mm) could be used to bypass the current limitation of scale. Each LED was
5mm in diameter with a 5mm space between each to limit light dispersion from adjacent
LEDs. A rectangular enclosure, consisting of six sides with finger edge joints was designed
(see Appendix Figure 6) with seven cavities (spaced 5mm apart) to house each of the LEDs.
Black material (3mm depth) was cut into six sides corresponding to the 2D design from
Illustrator. Acrylic adhesive was applied to finger edge joints to secure the rectangular
enclosure leaving the top side open (dimensions: 90x15x15mm). The LED chain was
manually inserted into the enclosure. Figure 5.1 shows the constructed LED enclosure.
Black Perspex Material Enclosure
(90x15x15mm)
LED
light source
Figure 5.1: LED enclosure for watch prototype with chain of seven LEDs situated inside.
Page 38 of 68
Aluna Everitt
SCC.300
2015
5.2 INTERFACE
The second stage of development involved adapting the previous SSD interface design
(dimensions: 100x120x5mm) to a smaller scale for a watch display. Although the enclosure
for the LED chain is 90mm in length the interface is much smaller to ensure discreteness as a
ubiquitous device. The display integrates a generic SSD interface (dimensions: 40x40mm)
with a rectangular extension that increases the length of the entire display by 10mm (see
Appendix Figure 7 for design outline). By extending the width to 80mm the display can
accommodate the larger enclosure situating the chain of seven LEDs. The whole interface
was 5mm in depth and included seven 3mm extensions at the bottom (see Figure 5.2). This
enabled the interface to be inserted firmly into the LED enclosure without need for adhesive.
Black material
inserts
Material
extension to
accommodate
chain of LEDs
Extension for
enclosure insertion
Figure 5.2: Refined display for interactive watch prototype. Consisting of optically clear Perspex (depth 5mm)
and corresponding black material partitions (width: 0.72mm).
The previous SSD design with black inserts was scaled down to accommodate the main
40x40mm interface with an elongated extension. Initially black cuts were simply extended to
the bottom of the display to isolate each of the individual LEDs. The width of cut was also
decreased to 0.5mm in order to reduce the presence of black material in the interface. The
initial display was cut from 5mm clear material with corresponding black material inserts.
The whole interface consisted of five separate segments and two black inserts. Acrylic
adhesive was used to secure the structure and ensure robustness and stability as a watch. It
was discovered that the use of acrylic adhesive disrupted the reflective properties of the clear
material when contact was made with the black inserts. This eliminated the reflective edges
of the cuts as seen in Figure 5.3. The reflective properties of the display were reduced if too
much adhesive was used.
Page 39 of 68
Aluna Everitt
SCC.300
2015
Area where no
adhesive
contact is made
with the clear
black material
Area where
adhesive makes
contact with
the clear black
material
Figure 5.3: Initial watch interface (secured with adhesive to ensure robustness) inserted into LED enclosure.
The initial interface design (see Figure 5.4) visualised each of the ten states needed to tell the
time using digits 0-9. However the top right segments did not illuminate well compared to the
other five segments. This was due to the limiting angle at which the etched segments were
located, i.e. 20mm away from their designated light sources. As a result the first display did
visualise figures proficiently in ambient light. Even when a darker background was used the
luminance of visualisation was not proficient. A fascia was used in an attempt to enhance the
visualisation of each etched section. However, the addition of a fascia did not enhance the
display as predicted.
Comparison of colour and etch observations highlighted current visualisation issues with the
initial design. The figures “6” and “9” were illuminated in order to inspect the majority of
segments. The refinement of the second interface (see Figure 5.5) was based on visual
inspection of angles and position of black inserts and etched sections with correspondence to
designated light sources.
Page 40 of 68
Aluna Everitt
SCC.300
2015
Figure 5.4: Due to angle restrictions the initial design of the display did not allow light to be transmitted
efficiently to the top sections as shown by numerals 6 and 9.
Certain colours enhanced the visualisation of etched section with more clarity as seen in
Figure 5.4. The colour green for figure “6” is much more prominent compared to figure “9”
illuminated in yellow.
Page 41 of 68
Aluna Everitt
SCC.300
2015
A second design was implemented with minor adjustments to angles of cuts and low edge
corners to ensure each segment is illuminated proficiently in full ambient light. Figure 5.5
compares prominence of illumination applied using the same figures for consistency.
Figure 5.5: Refined design of the display enhanced illumination of both figures regardless of light or dark
background and the addition of fascia.
The refined design considered angles of each black cut and expands areas of clear material
for each sections of the display where light rays struggled to have reached previously. The
initial design the colour yellow did not illuminate etched sections proficiently. The refined
design enhances the visualisation of each segment even when a yellow light source is used.
Page 42 of 68
Aluna Everitt
SCC.300
2015
5.3 INTERACTIVE BUTTON
A separate enclosure was designed for the interactive button element (dimensions:
90x15x9mm). This was a scaled down version of the original design based on the initial
button light switch. The button element could be scaled down even further for future work,
however in order to keep aesthetic consistency it was designed to be the same diameter as the
LED enclosure (see Appendix Figure 8 for laser cut outline).
The button enclosure consists of three layers of black material (3mm depth) with cavities for
an LDR to be situated in the middle layer and another cavity for an LED in the top layer. The
top layer acts as frame where clear optical material is inserted and is considered an actuator
for interactive capabilities. A standard sized LDR was used (dimensions: 5x4x2mm) as
smaller LDRs were too sensitive and picked up the frame rate of the LED. A capacitor could
also be added in future work to defuse frequency displacement. As the standard LDR did not
impact scale is was implanted instead. By excluding the need for a capacitor less electronic
components are required.
Three layers of laser cut black material are assembled together with active components
situated within designated cavities. A piece of clear optical material is cut corresponding to
size of the top layer frame (dimensions: 71x5x3mm) and is considered as the actuation
component for the interactive button. Figure 5.6 shows the final watch interactive button.
LDR
sensor
Button element enclosure
(90x15x9mm)
LED
light source
Transparent material
(71x5x3mm)
Figure 5.6: Button actuation device consisting of one LED, one LDR, and a strip of optically clear material.
User input must be configured, with consideration of ambient light, on the surface of the
material. First, light intensity average is calculated when no pressure is applied to the surface,
this is used as an actuation threshold for the watch. Secondly, light intensity average is
calculated when no pressure applied to the surface. This is used as a threshold to deactivate
visualisation if undeliberate interaction occurs. Ambient light in the environment must also
be taken into consideration as this disrupts readings from an LDR which is very sensitive.
Implementing a compositor in further work could eliminate ambient light noise from LDR
reading.
Page 43 of 68
Aluna Everitt
SCC.300
2015
5.4 FINAL INTEGRATION
Once the final interface was assembled a watch strap was designed to hold the watch on a
human wrist. The strap design was separated into two sections, one of each side of the
display. Hinges secured with adhesive enabled the user to adjust the tightness of the strap.
The combined light enclosure, interface, and interactive button produced a wearable watch
with interactive capabilities. The interface visualises each digit of current time in sequential
order once finger pressure is applied to the button. Performance was tested in ambient light
for quality in visualisation and interaction. Interactivity of the button was efficient when used
in an environment where ambient light levels did not change. Interactivity of the button did
not change when no ambient light was present. Figure 5.7 shows numerical digits visualised
on the interface. Each number can be distinctly identified and shown in a range of colours.
Due to the incoherent white balance of the camera used (IPad 4 camera) luminance of the
display is not as prominent in photographs. Nevertheless visualisation is enhanced when no
ambient light is present. A comparison of the display with no ambient light can be seen in
Figure 5.8.
Figure 5.7: Figures 0 to 9 displayed on final watch prototype in full ambient light. The middle section is no as
well illuminated compared the surrounding sections.
A range of colours was used to visualise individual digits to examine if certain colours enable
figures to be distinguish further. When ambient light is present red, green, and blue colours
were more distinguishable as seen in Figure 5.7. However, colour changes had little effect in
the visibility of figures when no ambient light was present.
Figure 5.8: Figures 0 to 9 displayed with no ambient light present. Each figure is visualised with greater clarity
though the middle segment is still less obvious.
Page 44 of 68
Aluna Everitt
SCC.300
2015
5.5 DISCUSSION AND SUMMARY
This chapter demonstrates the integration of singular active prototype elements into a unified
watch device with interactive capabilities. The example application proves how laser cut
optically clear material can be implemented to fabricate a wearable interactive display.
The combination of the LED enclosure, interface and interactive button enabled fabrication
of a purposeful interactive device that can be used in both darkness and daylight as seen in
Figure 5.9. By applying the design and fabrication process in context of wearable technology
it was demonstrated that interface scale should not be an issue in the design space. The main
limitation for this application was the large size of LEDs used. This means that the light
enclosure could not be discrete. In terms of visualisation, the luminosity of figures could be
enhanced further by limiting the space between the LEDs. With further refinements to the
discreteness of active components, by using smaller LEDs for example, devices could be
scaled down much more. Visualisation of meaningful information on transparent surfaces
enables further exploration of design space for new forms of interfaces.
WATCH USED WHEN NO
AMBIENT LIGHT IS PRESENT
WATCH USED WHEN AMBIENT
LIGHT IS PRESENT
Figure 5.9: Watch used when no ambient light is present compared to when ambient light is present.
In terms of interactivity, the button element was able to activate the display when ambient
light levels within the test environment stayed constant. If levels of ambient light increased a
new threshold levels must be set higher than previously to accommodate the change.
Otherwise the button would be activated with the present of ambient light. By adding a
capacitor to the LDR circuit ambient light is eliminated from the LDR readings.
Page 45 of 68
Aluna Everitt
SCC.300
2015
This would mean the addition of an extra electronic component to the fabrication process. An
alternative algorithm approach could also be implemented to eliminate effects of ambient
light affecting the light sensor.
The watch device could easily be customised by simply replacing detachable sections with
alternative objects. The transparent display is detachable from the main enclosure. This
allows users create new interfaces and replace them easily without the need to fabricate a
whole new device. Cost of material and lead time as a result is greatly reduced compared to
3D printing. The design decisions utilised in this report enabled the laser cut devices to have
detachable parts. This presents a rapid prototyping process of exploring design decisions
without the need to wait for creating a whole new object is enabled as components can easily
be replace from an existing object.
In conclusion the work in this chapter enables the design and fabrication of a fully interactive
watch prototype. The next chapter describes the fundamental process and approach to
fabricating interactive display prototypes.
Page 46 of 68
Aluna Everitt
SCC.300
2015
6. DESIGN CONSIDERATIONS AND DISCUSSION
The process of developing interfaces with interactive capabilities described in this chapter
consisted of three phases. First, optically clear material light properties were explored for
enabling visualisation and interactivity. Secondly, findings and observation were applied to
physical examples of single systems. Thirdly, a group of single systems were integrated to
produce a functioning interface device with interactive capabilities as a validation of the
process described in this chapter. Below the design considerations are presented to design and
fabricate interactive interfaces from laser cut Perspex.
6.1 APPARATUS
The apparatus consists of a hardware processing board, RGB NeoPixel Mini PCB LEDs
(datasheet details can be found below here1), and a standard sized light-dependent resistor
(LDR). Use simple transmitter and receiver components.
1. Computer aided design (CAD) software
a. 2D vector graphic tool - such as Illustrator.
2. Hardware
a. Arduino processing board (such as Uno, Mega, mini, or Nano).
3. For interactive element
a. 1x LED for emitting light rays.
b. 1x LDR for receiving emitted light rays.
4. For display
a. X number of LEDs corresponding to the number of sections required for the
display - E.g. seven-segment display use seven LEDs in a chain (one to
control illuminate each section individually).
6.2 DESIGN AND FABRICATION OF ENCLOSURE
Design an enclosure to house active components in a 2D vector based design space,
Illustrator CC used for this project. An enclosure is needed for situating electronic elements.
1. Draw outline of desired enclosure with cavities to expose LEDs and LDR to
necessary elements.
2. Base the design of enclosure on the size and measurements of active components.
3. Draw small cavity (for LDR) underneath clear material used for interactive elements.
4. Simple layer three structure recommended:
a. Top layer for exposing light emitting components (LEDs) for display and
housing optically clear material for interaction.
b. Middle layer for exposing light intensity receiver (LDR).
c. Bottom layer for support of active components.
5. Draw four holes for each corner of each layer which correspond with each other for
nuts and ballots to hold entire enclosure in place securely. This is the easiest design
approach for assembly, reassembly, and replacing components if needed.
1
https://learn.adafruit.com/downloads/pdf/adafruit-neopixel-uberguide.pdf
Page 47 of 68
Aluna Everitt
SCC.300
2015
6. Prepare laser cutter setting (for LaserPro Spirit GE please see Appendix Table 2)
a. Use higher power and low speed for cuts.
b. Use relatively high power and high speed for etches (for example: labels on
top layer of enclosure).
1. Use black Perspex material for enclosure as ambient light and stray emission from
LEDs is absorbed rather than reflected.
a. Recommended depth of material more than 3mm for robustness.
2. Once each layer of enclosure is cut and etched where appropriate combine each layer
in sequential order on top of each other.
3. Manually insert active components within their designated cavities.
4. Clear optical material should not be embedded into the enclosure but instead the
enclosure will be used to support a display which is detachable.
5. Once each layer or side of enclosure is cut assembly depending on initial 2D design
a. If holes are used for assembly, use nuts and bolts to hold enclosure object
structure firmly in place corresponding width of holes.
b. If finger edge joints are used it is recommended to apply acrylic adhesive for
best results and hold structure firmly in place.
c. Clear super glue could also work well.
6.3 DESIGN AND FABRICATION OF DISPLAY
The display is considered to be a separate element of the device which can be inserted on top
of the enclosure where cavities for the display’s LEDs are positioned. The display can be
scaled up or down depending on the needs and specifications.
1. Draw outline of display 2D vector based design software (such as Illustrator).
2. Draw segmented design that corresponds to the number of LEDs.
a. Use full colour fill for areas of display which are to be illuminated – these will
be etched – recommended for etching is crisscross pattern as light rays are
distributed more evenly throughout all of the section without illuminating the
direct path of light source - Each section of display which is to be visualised
individually.
3. Draw lines of no more than 0.72mm.
a. The minimum thickness of the blocking material is limited by its material
properties. Specifically it was observed that even black opaque Perspex
behaves like a translucent material when cut into thin slivers (<0.72mm thick)
4. Each path of cut should isolate an individual section of the display.
1.
2.
3.
4.
Optically clear Perspex material (depth no more than 1mm – for robustness).
Cut and etched transparent material using 2D vector design.
Cut inserts corresponding to cuts made in display from black material of same depth.
Manually situate black material inserts into clear display.
Page 48 of 68
Aluna Everitt
SCC.300
2015
5. Secure structure with clear adhesive if necessary. Aim to use as little as possible so as
not to disrupt reflective properties of any edges.
6.4 PROGRAMME DISPLAY
Each light-emitting diode (LED) must be designated to a single segment (see Figure 6.1). It is
not necessary to use multi-coloured LEDs. However, colour changing visualisations provide
an extra dimension of clarity when displaying sequential information using just one SSD.
Figure 6.1: To display numeric figure “3” LEDs 3, 4, 5, 6, and 7 must be active
whilst LEDs 1 and 2 must be inactive.
Multi coloured LEDs are activated and set colour using three input variables – red, green, and
blue (RGB). Figure 6.2 shows basic sequence of active and inactive states of each LED to
display numeric figure “3” in green. An Arduino Adafruit NeoPixel library function is used
for controlling single-wire-based LED pixels and strips of LEDs.
// Activate LEDs
pixel_01.setPixelColor(2, pixel_01.Color(0, 255, 0)); // LED 3
pixel_01.setPixelColor(3, pixel_01.Color(0, 40, 0)); // LED 4 less luminance for consistency
pixel_01.setPixelColor(4, pixel_01.Color(0, 255, 0)); // LED 5
pixel_01.setPixelColor(5, pixel_01.Color(0, 255, 0)); // LED 6
pixel_01.setPixelColor(6, pixel_01.Color(0, 255, 0)); // LED 7
// Inactive LEDs
pixel_01.setPixelColor(0, pixel_01.Color(0,0,0)); // LED 1
pixel_01.setPixelColor(1, pixel_01.Color(0,0, 0)); // LED 2
Figure 6.2: Example Arduino processing code for visualising numeric figure “3”.
Page 49 of 68
Aluna Everitt
SCC.300
2015
6.5 PROGRAMME INTERACTIVE ELEMENT
1. Take sample of light intensity when no pressure or contact is applied to surface of
clear material
a. Find average of at least 500 samples to eliminate chance of anomalies
b. Use average as threshold when no user input is present
2. Take sample of light intensity when low pressure contact is applied to surface of
material
a. Find average of at least 500 samples to eliminate chance of anomalies
b. Use average as threshold for first user input variable
3. Take sample of light intensity when high pressure contact is applied to surface of
material
a. Find average of at least 500 samples eliminate chance of anomalies
b. Use average as threshold for second user input variable
6.6 DISCUSSION AND SUMMARY
The main aim of this project was to contribute an alternative approach to designing and
fabricating interfaces with interactive capabilities. Based on initial explorations of light
properties a simplistic method of designing and producing interactive elements and visuals
displays has emerged. By integrating active comments a fully functioning watch prototype
was implemented.
The process described in this chapter outlines fundamental techniques for designing and
developing such active components that can be customised and altered to an individual’s
needs and specifications. Laser cutting enables a low cost and accessible method of
fabricating rapid prototypes. As a result a rapid process of exploring design decisions without
the need to wait for creating a whole new object has emerged.
Electronic components and material used throughout this project are low cost and easily
implemented without need for low level techniques skills. And design space demonstrated
within this project can be elevated further by exploring with a large scope of interactive
interface applications. The process described enables a creative approach to the design and
fabrication of interfaces that could be implemented by a large range of users who do not have
access to high cost optical 3D printers or poses high level 3D modelling knowledge. Design
space could be further extended to 3D curved displays with the use of light pipes of different
depths.
The main limitation of the current system is that user input threshold light intensity must be
calibrated manually when ambient light intensity within the environment changes. The
stability of interactive devices fabricated using the process presented is limited if constant
resets are needed to calculate user input threshold. An algorithm could be implemented to
eliminate ambient light data from LDR readings. Alternatively, a capacitor could be added to
the LDR circuit which would also eliminate ambient light readings. The addition of a
capacitor however, would mean an extra electronic component is added to the fabrication
process.
Page 50 of 68
Aluna Everitt
SCC.300
2015
In an attempt to capture how the general public would react to the novel interfaces developed
the prototypes were demonstrated in three consecutive sessions. In the wild observations
were written down based on unpremeditated feedback in an attempt to understand how
people respond to new forms of novel interfaces with interactive capabilities. Figure 6.3
comprises of words and phrases frequently mentioned when demonstrating prototypes
produced from this project across three consecutive sessions.
Figure 6.3: Word cloud of key phrases and words taken from observations conducting
during open day demonstrations.
Overall the unstructured feedback received from the general public was positive. Greater
interest was shows in the visual aspects on the prototypes demonstrated. This was mainly due
to the bright colours and high luminosity emitted that attracted higher interest. A number of
suggestions for possible application of this technology were suggested such as car windscreen
clocks and window displays. There was also excitement at the concept of implementing such
interfaces in social night club environments.
Each of the steps demonstrate the design and fabrication of individual components can be
integrated in create an interface display with interactive capabilities. The watch prototype
described and implemented shows that functioning interactive interfaces could be produced
with a limited number of active components using laser cutting techniques. The conclusion
chapter revisit objectives declared at the start of this report and analyse the solution outlined
throughout this project. Current limitations and future work is also discussed.
Page 51 of 68
Aluna Everitt
SCC.300
2015
7. CONCLUSION
This project demonstrated an alternative approach for rapid prototyping of novel interactive
interfaces. Using low cost and highly accessible optically clear Perspex material and adding
interactivity using basic light receiver sensor and light emitter. The design considerations for
this process should enable replication of similar devices. Extending this, alternative novel
approaches to interface implementation could also be explored by following the five inclusive
steps described previously.
The use of a laser cutter enables rapid fabrication of prototypes without the need of high level
knowledge of 3D modelling. Perspex material used for this project can be easily obtained at
low cost and offers higher quality finish compared to resin, Acrylonitrile Butadiene Styrene
(ABS), or Polylactic Acid (PLA) used for 3D printing.
7.1 REVIEW OF AIMS
The initial aims of project have been successfully met. A general approach was presented for
using laser cut Perspex prototype elements to display information and sense user input.
Techniques for visualising information using laser cut optically clear material, including use
of etchings and cuts to enhance luminosity of displays can be demonstrated by the
implementation of three varieties of seven-segment displays. Techniques for sensing user
input with laser cut transparent material were demonstrated through the application of a
button light switch and accelerometer. This involved touch pressure input with an embedded
sensor and manual displacement of light wave guides. An example application watch
prototype demonstrated how laser cut optically clear material could be implemented to
fabricate a wearable interactive display.
7.2 LIMITATIONS
In depth explorations of light studies should be conducted to ensure a more developed
understanding of light properties of optically clear Perspex plastic. Smaller LEDs for
visualisation and interactive purposes could be used to further scale down size of devices
fabricated. Refinement of etching style on the surface of the material could also enhance
valuation of information displayed. A varied range of applications should be designed and
tested to uncover limitations of laser cutting interactive prototypes. Only flat displays were
fabricated and this limits current knowledge of possible implementations of curved and 3D
surface displays.
Optical properties of materials other than Perspex should also be explored in order to extend
current findings from this project to a larger scope. When ambient light is present certain
segments are occluded by others and do not illuminate as prominently. Further explorations
of interface design must be made to enable enhanced visualisations of information without
any inconsistencies. The laser cutter used throughout this project also varied in quality and
precision of cuts and etches due to maintenance issues. As a result laser induced damage to
the material decreased quality of optical illumination.
Page 52 of 68
Aluna Everitt
SCC.300
2015
7.3 FUTURE WORK
Although the original aims of this project have been met, further refinements and extensions
of studies can be implemented in the future. Implementation of alternative interface designs
with curved surfaces and extrusions would contribute to current fabrication process available
in the field. Extending light studies by exploring effects of light intensity in a range of widths
and scales of material would build upon current understanding of optical light properties of
Perspex.
Algorithmic implementations of interface designs should also be considered in future work.
A 2D vector design system could be developed where users draw their interface segments
have black insert cuts algorithmically generated. With reference to Aurenhammer [1]
Voronoi diagrams geometric paths could be computed in order to isolate each segment based
on the nearest neighbour concept as seen in Figure 7.1. This would reduce the need for a user
to manually design black insert cuts for an interface.
Figure 7.1: Voronoi diagram isolating each of the eight points with maximum space around each centre.
7.4 LEARNING OUTCOMES
Throughout the duration of this project a range of skills and knowledge was obtained. I have
encountered new forms of prototype fabrication with the support of Computer Aided Design
(CAD). I now have proficient knowledge of operating a laser cutter for a wide range of
applications. My knowledge of electronics and circuit board implementations has enabled me
to not just design devices but also produce rapid high fidelity prototypes efficiently. My
Arduino programming skills have greatly aided the progress of this project and have been
further enhanced through the range of applications used such as conducting lighting studies
and visualising meaningful information using just seven LEDs. This project enabled me to
explore new possibilities for interactive interfaces and sensors using simple laser cutting
techniques. Overall the process derived from this project successfully enables a novel
approach to fabricating interactive interfaces and sensors using simple laser cutting
techniques and two electronic components (light source and light sensor).
Page 53 of 68
Aluna Everitt
SCC.300
2015
BIBLIOGRAPHY
[1] Aurenhammer F. (1991) Voronoi diagrams—a survey of a fundamental geometric data structure.
ACM Computing Surveys (CSUR), 23(3), 345-405.
[2] Baudisch P., Becker T. & Rudeck F. (2010, April). Lumino: tangible blocks for tabletop
computers based on glass fiber bundles. In Proceedings of the SIGCHI Conference on Human Factors
in Computing Systems (pp. 1165-1174). ACM.
[3] Bergman D. J. and Stockman M. I. (2003) Surface plasmon amplification by stimulated emission
of radiation: quantum generation of coherent surface plasmons in nanosystems. Physical review
letters, 90(2), 027402.
[4] Blöchl P. E. (1994) Projector augmented-wave method. Physical Review B,50(24), 17953.
[5] Brockmeyer E., Poupyrev I. & Hudson S. (2013) PAPILLON: Designing Curved Display Surfaces
With Printed Optics for USIT (2013).
[6] Han J. Y. (2005). Low-cost multi-touch sensing through frustrated total internal reflection. In
Proceedings of the 18th annual ACM symposium on User interface software and technology (pp. 115118). ACM.
[7] Han J. Y. (2008) U.S. Patent No. 20,080,284,925. Washington, DC: U.S. Patent and Trademark
Office.
[8] Lin R. (2003) U.S. Patent No. D469,089. Washington, DC: U.S. Patent and Trademark Office.
[9] Mader A., Dertien E. & Reidsma D. (2012) Single value devices: In Intelligent Technologies for
Interactive Entertainment (pp. 38-47). Springer Berlin Heidelberg.
[10] Mueller S., Kruck B. & Baudisch P. (2013) LaserOrigami: laser-cutting 3D objects. In
Proceedings of the SIGCHI Conference on Human Factors in Computing Systems (pp. 2585-2592).
ACM.
[11] Orchard A. R. (1993) U.S. Patent No. D337,104. Washington, DC: U.S. Patent and Trademark
Office.
[12] Rümelin S., Beyer G., Hennecke F., Tabard A. & Butz A. (2012) Towards a Design Space for
Non-Flat Interactive Displays. In ITS (2012)
[13] Savage V., Schmidt R., Grossman T., Fitzmaurice G. & Hartmann B. (2014) A Series of Tubes:
Adding Interactivity to 3D Prints Using Internal Pipes For UIST (2014)
[14] Suman M. J., Welling T. L. & Schneider R. J. (1998) U.S. Patent No. 5,822,023. Washington,
DC: U.S. Patent and Trademark Office.
[15] Takada Y., Kanagawa K., Nakabayashi R. & Kanagawa K. (2012) Ficon: a Touch-capable
Tangible 3D Display using Optical Fiber. In ITS (2012)
[16] Wills K., Brockmeyer E., Hudson S. & Poupyrev I. (2012) Printed Optics: 3D Printing of
Embedded Optical Elements for Interactive Devices for UIST (2012)
Page 54 of 68
Aluna Everitt
SCC.300
2015
APPENDICES
PROTOTYPE ELEMENTS
Appendix Figure 1: Button light switch enclosure design outline.
Appendix Figure 2: Accelerometer enclosure outline.
Page 55 of 68
Aluna Everitt
SCC.300
2015
SEVEN-SEGMENT DISPLAY CHAPTER
Appendix Figure 3: Enclosure for initial SSD with cavities for LEDs to be situated on all four sides of the display.
Appendix Figure 4: Enclosure for second SSD with cavities for LEDs to be situated only on the bottom of the
display.
Page 56 of 68
Aluna Everitt
Test #
1
Etch/Cut
Etch
SCC.300
Speed
60
Power PPI
70
500
Material
Depth
3mm
Etching
Type
Matt
LED
Image
Birghtness
100
2015
Result
Result Comments
Real Life: Etched edges closest to LEDs
are brightest - can see direction of light
rays on fully matt etched surface
panning out - middle segment not
obvious - very hard to differentiate
between segments which are intended
to be on and off
Photo Result: Illumination of segments
more prominent compared to real life light does not fill whole segment - issue
with illuminating middle segment Need guide and manipulate light waves
2
Etch
60
40
625
3
Cut (16)
1
75
400
3mm
Dots
100
Same as Test 3 but without middle cuts
100
Real Life: Display still not obvious
enough - cuts in plastic guide light more
reflection and more illumination display is very bright - very hard to make
out any difference
4
Etch
60
50
625
3mm
Dots
100
Photo Results: Pretty much the same as
real life
5
6
Cut
(0.01 inch)
Etch
1
60
100
50
1500
625
100
3mm
Matt
100
Real Life: Matt etching works better more obvious which segments are
illuminated - could enhance further interesting reflection behaviour for
middle section - cuts guide the light
waves efficiently - the middle segment
is illuminated more obviously
Photo Results: Contrast is more
emphasised due to white balance in the
camera - effect of illumination more
prominent
7
Cut
(0.01 inch)
1
100
1500
8
Etch
70
50
625
3mm
Dots
100
Matt/
Dots
100
Same as Test 3
Real Life: Outside section illuminated
more prominently - middle section not
as much - display overall very bright need less light by having less cuts?
Photo Results: middle section much
better shown in photo than in real life
Appendix Table 1: Visual observational findings from initial SSD design explorations with power
and speed used.
Page 57 of 68
Aluna Everitt
SCC.300
2015
Appendix Figure 5: Single layer SSD display were LEDs are situated at the bottom.
Etch
Cuts
Speed
80
0.7
Power
90
100
PPI
1000
1500
Appendix Table 2: Most effective setting for cutting and etching Perspex Material (5mm depth) for SSD display
Page 58 of 68
Aluna Everitt
SCC.300
2015
WATCH CHAPTER
Appendix Figure 6: Watch prototype LED enclosure laser cutter design with cavities on top side for LEDs.
Appendix Figure7: Final watch display laser cut design.
Appendix Figure 8: Button for watch laser cut design.
Page 59 of 68
Aluna Everitt
SCC.300
2015
PROJECT PROPOSAL
Illuminative interactive interfaces are becoming more prominent as the manipulation of
optics2 is becoming an integral part of sensing, display and illumination of interactive
devices. This project proposes a design model which enables the development of various
novel interfaces with emphasis on using an easily accessible medium of Perspex sheets and
laser-cutting. One of the main aims of this project is exploring the relationship between light
waveguides using frustrated total internal reflection (FTIR3) and by laser-cutting Perspex to
desired specifications. As a result of the lighting experiments, the project aims to generate an
accessible design model which end-users are able to adopt with ease and flexibility to
construct interfaces for particular needs. Understanding the relationships involved with lasercutting reflective behaviour and diffusive properties of light interaction with etched surfaces,
all account towards establishing a primary model that end-users are able to understand and
implement.
This project aims to design and implement a variety of novel interfaces through modelling
light waveguides and constructing them via laser-cutting and etching with capabilities of
direct user input via touch sensing. Establishing principles for a design model is the main
focus of the project. End-users, who wish to create novel illuminative interfaces via laser
cutting and etching, can also implement their ideas with ease via the developing design
model. This report covers the background of how novel interfaces are created using
manipulated optics, frustrated total internal reflection, laser cutting techniques and manual
ray tracing. In the background section there is also discussion on how the current research can
be implemented and further developed through this project in order to surpass limitations.
The proposed project section covers details regarding the methods used to develop the
indented novel interfaces and the experimental elements of the study. Specific details of the
main objectives and a breakdown of the phases required to complete the project can be also
be found as well as a Gantt diagram showing the breakdown of tasks. Required resources are
also listed as well as references used for this report.
2
+ 3 Printed Optics: 3D Printing of Embedded Optical Elements for Interactive Devices
- Karl D.D. Willis - Eric Brockmeyer - Scott E. Hudson - Ivan Poupyrev
3
Frustrated Total Internal Reflection: A demonstration and review http://www.cleyet.org/Misc._Physics/Microwave-Optics/Evanescent-FTIR/FTIR%20review.pdf 15/05/2014
Page 60 of 68
Aluna Everitt
SCC.300
2015
With recent innovation in optical quality 3D printing, it is now possible to construct novel
interfaces designed for specific needs and purposes. There is now emphasis on creating
devices that can be modelled as a single object without the need to have individual circuit
boards and assembly parts. 3D Printed Optics4 now allows for rapid prototyping of interactive
devices with fabrication techniques such as Sensing Displacement embedded within devices
during their creation. Sensing Displacement is a fabrication technique that uses an infrared
emitter that releases light rays through a transparent material (Perspex for instance) which
can be recorded by an infrared receiver. The IR receiver is able to register high or low
readings and from these can determine if there has been any physical interaction made on the
surface of the device. 3D printing is predominantly a high cost technique that is rarely
accessible to most people whereas the proposed use of laser-cutting and etching would
produce the desired effect at a lower cost and in less time.
Sauron5 is an embedded single-camera sensing for printing physical user interfaces that aids
designers in developing prototypes that are ready action objects. With minimum assembly
and wiring, Sauron assists designers in creating rapid prototypes that are interactive from the
start. With inspiration from Sauron’s system this project also aims to develop a model that
can relate to principles of rapid prototyping of active objects by deriving possible interactive
elements of devices early on in the design process.
As this project will entail the use of laser-cutting as opposed to 3D printing, which is more
expensive in monetary terms, it is key to explore different possibilities for using the laser
cutter. A concept inspired by research Stefanie Mueller into LaserOrigami6 can prove to be
an aid when designing and assembling novel interactive devices for this project.
LaserOrigami is a rapid prototyping system that produces a 3D object via a laser cutter, this is
a much faster fabrication technique compared with 3D printing and even standard lasercutting as there is no manual assembly. Although the prototypes created through
LaserOrigami are static objects, the techniques for fabrication can aid the design and
assembly of devices for this project.
Frustrated Total Internal Reflection was first developed for interactive multi-touch tables by
Jeff Hans7 . As light enters the core of a transparent material the ray is reflected through the
core if the wave strikes a medium boundary at an angle larger than that of the angle of the
surface boundary.
5
Sauron: Embedded Single-Camera Sensing of Printed Physical User Interfaces - Valkyrie Savage, Colin
Chang, Bjorn Hartmann - 2013
6
LaserOrigami: Laser-Cutting 3D Objects - Stefanie Mueller, Bastian Kruck, and Patrick Baudisch - 2013
7
Low-Cost Multi-Touch Sensing through Frustrated Total Internal Reflection – Han, J. Y 2005 (In Proceedings
of the 18th Annual ACM Symposium on User Interface Software and Technology)
Page 61 of 68
Aluna Everitt
SCC.300
2015
As shown in Figure 1 any interaction/frustration
with the outside of the surface causes light rays
within the core to escape from the boundaries
into the air. This project will adapt FTIR to
different technologies, such as wearable
devices, instead of just interactive tables.
Diagram of a finger touch that is used to frustrate
the light waveguide – FTIR
*Taken from: http://cs.nyu.edu/~jhan/ftirsense/
The main aim of this project is to develop novel displays with input capabilities through
laser-cutting Perspex plastic to construct and model light waveguides. This project will focus
on using laser-cutting and Perspex plastic as opposed to 3D printing as it is considered to be
more accessible to most people. With the fabrication of successful novel interfaces complete,
it will also be beneficial to explore how end-users would be able to implement their own
ideas via laser-cutting and etching in an efficient and affordable way.
By exploring and understanding patterns from lighting experiments conducted at the start of
this project a variety of prototypes with input functionality will be developed. Each
successful prototype will be evaluated and compared against one another in order to establish
a model of design patterns that can be implemented for specific requirements and this will
result in a design model represented via an infographic.
Light
Experiments
List of Behaviours
and Patterns
Design Model
(Infographic)
Prototype
1
Prototypes
Prototype
2
This diagram represents the workflow
of this project
Prototype
3
Project
Report
Page 62 of 68
Aluna Everitt
SCC.300
2015
These novel displays will be constructed by laser-cutting and etching Perspex plastic sheets
and applying LED lights to one end of the cut transparent plastic, modelling specific light
waveguides that can manipulate photons to illuminate particular areas when needed to display
graphics. The user will be able to touch the surface of the plastic directly. This in turn will
disturb the light rays and cause them to scatter outside of the core of the Perspex. This change
in the light ray behaviour (intensity/direction/destination) can be used as an input variable for
interaction detection.
The project will involve two main phases. Beginning with experimenting and establishing
behavioural patterns of visible light interacting with Perspex via ray-tracing and manipulating
FTIR8 elements, a model of similar patterns can be observed. This design model will form
principles that shall aid the creation of prototypes in the second phase of this project. An
optional additional third phase can be implemented for user evaluation and focus group
testing on the design model.
Activity 1 - The familiarisation of laser cutter in order produce quality laser cut objects.
Explore different laser cuts and etching techniques to establish the core foundation for the
project.
Activity 2 - Understand how light rays can be manipulated to produce a desired result of
specified illumination. This is one of the key aims of this project. By using etching to defuse
reflections and laser-cutting to construct pathways for reflection and refraction, this project
will explore how laser-cutting Perspex in particular ways can affect light intensity and
illumination. The recorded results of this activity should produce a list of behaviours and
their characteristics.
Activity 3 – Deliver interaction using Frustrated Total Internal Reflection (FTIR), where the
scattered light ray readings recorded by the IR receiver can be used to manipulate the
interface by changing the paths of light rays traveling through the core of the Perspex. A
small Arduino can record the input transmitted by the IR receiver or even a Light Dependent
Resistor (LDR) and visualise the results.
Activity 4 - Generate an infographic/diagram representing the patterns and relationships
found between etchings, laser-cutting and light intensity. This will inform the development of
prototypes in phase two.
8
http://wiki.nuigroup.com/FTIR
Page 63 of 68
Aluna Everitt
SCC.300
2015
The second phase of the project will involve creating functional prototypes.
Activity 5 - Establish templates for a functional set of prototypes which correspond to
patterns found in the lighting experiments conducted in phase one.
Activity 6 - Create prototype one.
Activity 7 - Create prototype two.
Activity 8 - Create prototype three.
Activity 9 - This is the final activity of the project and will conclude with a written report of
all findings gathered from this project.
The novel interfaces will include touch sensitive wearable
technology such as a bracelet (Figure 3), which could
implement multiple input capabilities9 10. This will be done by
using Frustrated Total Internal Reflection (FTIR) to
manipulate light waveguides to avoid occlusion as the light
source would be at the back of the bracelet while the
illuminations will occur at the front, where the user is able to
view the display.
In addition to this example, an interactive keyboard may also
be developed by modelling light waveguides to specifications
and using a “planar waveguide11” system made from Perspex
that is laser cut and etched. This illuminative keyboard will be
capable of display a QWERTY style keystroke layout with
input and output functionality through the frustration of light
rays trapped within the “core” of the Perspex.
These are just two examples of possible interfaces that can be
Possible design for an interactive
developed using simple Perspex material and laser-cutting.
rd
The 3 prototype developed for this project will take into
bracelet
account a variety of possible interactive displays that can be created.
9
http://www.prnewswire.com/news-releases/interactive-led-wristbands-are-lighting-up-shows-and-events258647261.html 17/05/2014
10
http://www.ecouterre.com/the-dial-is-an-illuminated-rotary-phone-for-your-wrist/dial-phone-bracelet-2/
17/05/214
11
http://electron6.phys.utk.edu/light/10/light_guides.htm 15/05/2014
Page 64 of 68
Aluna Everitt
SCC.300
2015
This phase is only feasible after the project has secured successful results from the first two
phases and there is still time to implement additional work for this phase. This 3rd phase will
involve implementing a framework system, which can be presented to a focus group. The
focus group will be able to evaluate the system and their feedback will establish key
principles of how end-users intend to develop their own ideas into specific novel interfaces.
A design workshop will uncover the functional and non-functional requirements of such a
modelling system through a focus group review.
Illuminative interfaces have the potential to stimulate the users both visually and physically,
but they lack a design model which would aid their construction. As a solution to this
problem, this project aims to generate a series of tests that explore the manipulation of light
waveguides, light reflection and refraction within the core of Perspex plastic. Exploring how
Frustrated Total Internal Reflection (FTIR) can be best implemented in order to allow the use
of the Perspex surface as an input mechanism.
Although many interactive object oriented interfaces employ the use of 3D printing as their
primary tool, 3D printing is still highly inaccessible and expensive for public use. Perspex
plastic is more accessible and cheaper in terms of size compared to 3D printer filament and
resin (for gluing). A laser cutter can implement the same geometric properties to a shape as a
3D printer but a lot faster also. It is clear that the use of laser-cutting and Perspex material is
more cost efficient compared with 3D printing as well as easier for end-users to create their
visions via laser cutting.
Page 65 of 68
9
8
7
6
5
4
3
2
1
Activity
Number
Write Project Report discussing all
relevant findings
Implement functional prototype 3
Implement functional prototype 1
(Bracelet concept possibility)
Implement functional prototype 2
(Keyboard concept possibility)
Familiarise laser cutter and
construct basic primitives from
laser-cutting Perspex
Experiment with etching and
lase-cutting to uncover
behavioural patterns
Explore FTIR input and interactivity
capabilities
Develop design model that can be
applied to rapid prototyping
Establish working pattern that can
be applied to various prototype
concepts
Task Description
W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 W17 W18 W19 W20
Aluna Everitt
SCC.300
2015
Page 66 of 68
Aluna Everitt
1.
2.
3.
4.
SCC.300
2015
Access to Illustrator and other vector based software for design of interfaces
Prototype modelling via 3D software such as AutoDesk Inventor
Access to laser cutter
Electrical components needed include:
o Arduino – For control and readings
o LED lights (IR emitters)
o IR receivers
o Light Dependent Resistors (LDR)
Papers:
Printed Optics


Printed Optics: 3D Printing of Embedded Optical Elements for Interactive Devices by Karl
D.D. Willis, Eric Brockmeyer, Scott E. Hudson and Ivan Poupyrev – 2013
Frustrated Total Internal Reflection (FTIR)

Frustrated Total Internal Reflection: A demonstration and review by S. Zhu, A. W
Yu, D. Hawley, and R. Roy – 1985
Low-Cost Multi-Touch Sensing through Frustrated Total Internal Reflection
by Han, J. Y - 2005 (In Proceedings of the 18th Annual ACM Symposium on User
Interface Software and Technology)

Sauron
Sauron: Embedded Single-Camera Sensing of Printed Physical User Interfaces by
Valkyrie Savage, Colin Chang and Bjorn Hartmann – 2013

LaserOrigami
LaserOrigami: Laser-Cutting 3D Objects by Stefanie Mueller, Bastian Kruck, and
Patrick Baudisch – 2013
Websites:



Light Waveguides
http://electron6.phys.utk.edu/light/10/light_guides.htm
Sourced - 15/05/2014
Frustrated Total Internal Reflection (FTIR)
http://cs.nyu.edu/~jhan/ftirsense/
Sourced - 15/05/2014
http://wiki.nuigroup.com/FTIR
Sourced - 18/05/2014
Page 67 of 68
Aluna Everitt
SCC.300
2015
Prototype Concepts Inspiration

http://www.prnewswire.com/news-releases/interactive-led-wristbands-are-lighting-up-showsand-events-258647261.html
Sourced - 17/05/2014

http://www.ecouterre.com/the-dial-is-an-illuminated-rotary-phone-for-your-wrist/dialphone-bracelet-2/
Sourced - 17/05/2014

LaserOrigami
http://stefaniemueller.org/
Sourced – 17/05/2014
Page 68 of 68