“Introduction to Human factors engineering and
different types of equipment used in Ergonomics
lab”
Introduction:
Human Factors and Ergonomics is the discipline of designing products and systems to match the abilities of
people in order to improve productivity, safety, performance, and user satisfaction. The terms human-factors
engineering and human engineering are used interchangeably on the North American continent. In Europe,
Japan, and most of the rest of the world the prevalent term is ergonomics, a word made up of the Greek
words, ergon, meaning “work,” and nomos, meaning “law.” Despite minor differences in emphasis, the terms
human-factors engineering and ergonomics may be considered synonymous. Human factors and human
engineering were used in the 1920s and ’30s to refer to problems of human relations in industry, an
older connotation that has gradually dropped out of use.
Human Factors is that field which is involved in conducting research regarding human psychological, social,
physical, and biological characteristics, maintaining the information obtained from that research, and working to
apply that information with respect to the design, operation, or use of products or systems for optimizing human
performance, health, safety, and or habitability. Another definition of human factor engineering May be that
Human Factors is concerned with the application of what we know about people, their abilities, characteristics,
and limitations to the design of equipment they use, environments in which they function, and jobs they perform.
OBJECTIVES:
The objectives of this lab are listed below:
a. Understanding the concept of Human Factors Engineering Lab.
b. Understanding the importance and principles of Human Factors Engineering Lab.
c. Knowing the tools and equipment used in Human Factors Engineering Lab.
d. To get aware about the applications of Human Factors Engineering in industry.
e. The main
objective of the lab is to provide operating personnel with the resources they need for their work, so that they
can achieve the required performance in terms of safety, quality, reliability and availability and to provide
working conditions that minimize risks to health.
IMPORTANCE:
The concepts of Human factors Engineering Lab are important because:
• A task should not require workers to stay in awkward positions, such as reaching, bending,
or hunching over for long periods of time.
• Workers need to be trained in proper lifting techniques. A well designed job should minimize how far and
how often workers have to lift.
• Standing work should be minimized, since it is often less tiring to do a job sitting than
standing.
• Job assignments should be rotated to minimize the amount of time a worker spends doing
a highly repetitive task, since repetitive work requires using the same muscles again and
again and is usually very boring.
MAJOR PRINCIPLES:
The major principles of Human factors Engineering Lab are listed below:
• It is generally most effective to examine work conditions on a case-by-case basis when
applying Human Factors principles to solve or prevent problems.
• Sometimes minor ergonomic changes in the design of equipment, workstations or job tasks
can make significant improvements
Workers who may be
affected by any ergonomic changes in the workplace should be
involved in the discussions before changes are made. Their input can be very helpful in
determining necessary and appropriate changes.
LAB EQUIPMENT:
Our Human Factors Engineering Lab consists of the following equipment:
1. Wet Bulb Global Temperature Meter.
2. Psychrometer.
3. Automatic Cycle Machine.
4. Treadmill Machine.
5. Digital Light Meter.
6. Sound Level Meter.
Other Equipment:
Thermal Coupler
Thermal coupler, mostly known as thermocouple, is a measuring device where a certain technology is used to
gauge temperature. The coupler is good to use as a household device or in industries and at different places, it
serves different purposes.
FIGURE 1.1
Oxygen Analyzer:
Oxygen analyzer is a full function, full portable analyzer that can be used to make oxygen
measurement in open area and also in closed area.
FIGURE 1.2
Stress Meter
Instrument for measuring pressure changes in rocks that result from mining operations. The stress meter has a
steel shaft with a groove containing glycerin. When pressure is exerted, the glycerin is squeezed on to a diaphragm
which pushes a strain gauge to measure the movement.
FIGURE 1.3
Heart Rate Monitor:
A heart rate monitor is a personal monitoring device that allows one to measure one's heart rate in real time or
record the heart rate for later study.
FIGURE 1.4
Audiometer
An instrument for testing the intensity and frequency range of sounds that is capable of detection by the human
ear
FIGURE 1.5
Spirometer
A spirometer is an apparatus for measuring the volume of air inspired and expired by the lungs. A
spirometer measures ventilation, the movement of air into and out of the lungs.
FIGURE 1.6
APPLICATIONS:
The applications of human factors engineering are listed below:
1. USEABILITY TESTING:
Human factors engineers test new systems and equipment under real-world conditions as
much as possible, in order to identify potential problems and unintended consequences of
new technology.
2. EQUIPMENT USED IN ERGONOMICS LABORATORY:
The General Ergonomics and Human Performance Laboratory is used for both
undergraduate and graduate experimentation and demonstrations. It includes equipment for
performance assessment (reaction time, performance time etc.)
Summary:
There are so many other instruments which is used ergonomically for various purpose but these are
the main equipment’s which are discussed above with some necessary description.
Conclusion:
In this lab we study about the Human factor engineering lab introduction and its labs equipment.
Lab Report: 02
To Determine the Electrode Sensor Location (BiPolar Configuration) For Electromyography
Assessment of Superficial Skeletal Muscles
Introduction:
Electromyography (EMG), the measurement of electrical muscle activity, is used in a variety of applications,
including myoelectric upper-limb prostheses, which help amputees to regain independence and a higher quality
of life. The state-of-the-art sensors in prostheses have a conductive connection to the skin and are therefore
sensitive to sweat and require preparation of the skin. They are applied with some pressure to ensure a
conductive connection, which may result in pressure marks and can be problematic for patients with circulatory
disorders, who constitute a major group of amputees.
Due to their insulating layer between skin and sensor area, capacitive sensors are insensitive to the skin
condition, they require neither conductive connection to the skin nor electrolytic paste or skin preparation. Here,
we describe a highly stable, low-power capacitive EMG measurement set-up that is suitable for real-world
application. Various flexible multi-layer sensor set-ups made of copper and insulating foils, flex print and
textiles were compared. These flexible sensor set-ups adapt to the anatomy of the human forearm, therefore they
provide high wearing comfort and ensure stability against motion artefacts.
Figure 1: Bi Polar Electrodes Placement
Objectives:
The main objectives of this lab are
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To know about the concept of electrode sensor location for Electromyography (EMG).
To understand the Electromyography (EMG) assessment.
To understand the procedure of Electromyography (EMG).
To study different types of Electromyography (EMG) electrodes.
Procedure:
Needle EMG Procedure:
 A needle EMG test measures how well the muscles respond to electrical impulses.
 A neurologist or assisting technician will insert one or more thin, sterile needles into the muscle. This may
cause some minor discomfort in some people.
 The needles detect the electrical activity of muscles at rest and while contracted.
 The needle electrodes transmit this information to a device called an oscilloscope, which displays
electrical signals as waves.
 Once the test is finished, the neurologist or technician will remove the needle or needles.
 This test usually examines several nerves and muscles and lasts about 1 hour, but it may take longer
depending on how many nerves the neurologist wants to test.
Needle (Electrode) EMG Types:
There are three types of electrodes (needles) in EMG:
 Active Electrodes (Blue).
 Active Electrode (Yellow).
 Reference Electrode (Black).
NCV Procedure:
 A neurologist will most often administer an EMG test alongside an NCV test, according to the National
Institutes of Health (NIH).
 An NCV test measures the strength and speed of electrical impulses as they move through nerves. Doctors
often use these results alongside those of an EMG test to get a full picture of what is going on with a
person’s nerves.
 During an NCV test, the neurologist will ask a person to sit or lie down. Once the person is ready, they
will attach a recording electrode to the skin above the nerve or nerves under investigation. They will attach
a second electrode about 20 millimetres away.
 This electrode emits low voltage electric shocks that activate the nerve.
 Some people may experience mild discomfort during this part of the test. However, the electric shocks
should not cause pain, and any discomfort usually resolves once the test is over.
 The recording electrode detects the electrical impulse as it passes through the nerve and transmits the
response to a computer monitor.
After EMG test:
 After an EMG test, the neurologist or technician will clean the skin, and a person should be able to return
to their normal activities.
 However, they may experience some soreness and bruising for a few days afterward.
Lab Report: 03
Introduction to Electromyography (EMG) and its
importance in human factor engineering.
Introduction:
Electromyography is an electro diagnostic medicine technique for evaluating and recording the electrical
activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph to
produce a record called an electromyogram.
Electromyography (EMG) is a diagnostic procedure to assess the health of muscles and the nerve cells that
control them (motor neurons). Motor neurons transmit electrical signals that cause muscles to contract.
An EMG uses tiny devices called electrodes to transmit or detect electrical signals. Electromyography (EMG) is
an electro diagnostic medicine technique for evaluating and recording the electrical activity produced
by skeletal muscles. EMG is performed using an instrument called an electromyography to produce a record
called an electromyogram. An electromyograph detects the electric potential generated by muscle cells when
these cells are electrically or neurologically activated. The signals can be analysed to detect medical
abnormalities, activation level, or recruitment order, or to analyse the biomechanics of human or animal
movement.
In the figure 1 below it is shown that the electrodes are placed on the hands of patient and Doctor is giving
shocks to see the reaction.
Figure 2: EMG, Electrodes are placed on the hands and shock is also being given
Objectives:
The main objectives of this lab are
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
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To know about the concept of Electromyography (EMG).
To understand the purpose of doing Electromyography (EMG).
To understand the steps involved in Electromyography (EMG).
To get aware about the applications of Electromyography (EMG).
Purpose of EMG:
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Motor nerve cells, or neurons, transmit electrical signals from the central nervous system to the muscles.
The electrical signals from the nerves trigger muscle contractions.
Motor nerves control skeletal muscle activity, such as walking, speaking, and breathing.
Damaged or diseased muscle fibres do not function or respond to nerve impulses appropriately.
If the motor nerves are damaged or diseased, they can send abnormal electrical signals to the muscles.
EMG tests also provide information that doctors can use to determine the location and extent of muscle
and nerve damage.
Symptoms for EMG:
A doctor may order an EMG test if a person has symptoms of a muscle or nerve condition. Such symptoms may
include:
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muscle weakness or stiffness
twitching, cramping, or spasms
loss of fine motor control
difficulty speaking, chewing, or swallowing
persistent pain in the feet, legs, arms, or hands
numbness, tingling, or paralysis in the limbs
Procedure:
Steps for EMG:
There are two important steps involved in EMG that are listed below:
1. Nerve Conduction Study.
2. Needle Examination for Muscle testing.
Techniques in EMG:
Skin Preparation and Risks:
The first step before insertion of the needle electrode is skin preparation. This typically involves simply
cleaning the skin with an alcohol pad. The actual placement of the needle electrode can be difficult and depends
on a number of factors, such as specific muscle selection and the size of that muscle. Proper needle EMG
placement is very important for accurate representation of the muscle of interest, although EMG is more
effective on superficial muscles as it is unable to bypass the action potentials of superficial muscles and detect
deeper muscles. Also, the more body fat an individual has, the weaker the EMG signal.
Surface and Intramuscular EMG Recording Electrodes:
There are two kinds of EMG: surface EMG and intramuscular EMG. Surface EMG assesses muscle function by
recording muscle activity from the surface above the muscle on the skin. Surface electrodes
are able to provide only a limited assessment of the muscle activity. Surface EMG can be recorded by a pair of
electrodes or by a more complex array of multiple electrodes. More than one electrode is needed because EMG
recordings display the potential difference (voltage difference) between two separate electrodes. Limitations of
this approach are the fact that surface electrode recordings are restricted to superficial muscles, are influenced
by the depth of the subcutaneous tissue at the site of the recording which can be highly variable depending of
the weight of a patient, and cannot reliably discriminate between the discharges of adjacent muscles.
Maximal Voluntary Contraction:
One basic function of EMG is to see how well a muscle can be activated. The most common way that can be
determined is by performing a maximal voluntary contraction (MVC) of the muscle that is being tested. Muscle
force, which is measured mechanically, typically correlates highly with measures of EMG activation of muscle.
Most commonly this is assessed with surface electrodes, but it should be recognized that these typically only
record from muscle fibers in close approximation to the surface.
EMG Signal Decomposition:
EMG signals are essentially made up of superimposed motor unit action potentials (MUAPs) from several
motor units. For a thorough analysis, the measured EMG signals can be decomposed into their constituent
MUAPs. MUAPs from different motor units tend to have different characteristic shapes, while MUAPs
recorded by the same electrode from the same motor unit are typically similar. Notably MUAP size and shape
depend on where the electrode is located with respect to the fibres and so can appear to be different if the
electrode moves position. EMG decomposition is non-trivial, although many methods have been proposed.
Applications:
There are many applications for the use of EMG. EMG is used clinically for the diagnosis of neurological and
neuromuscular problems. It is used diagnostically by gait laboratories and by clinicians trained in the use of
biofeedback or ergonomic assessment.
Lab Report: 04
Structure, Function & Contraction Mechanism of
Skeletal Muscles
Introduction:
Skeletal muscle is one of three major muscle types, the others being cardiac muscle and smooth muscle. It is a
form of striated muscle tissue which is under the voluntary control of the somatic nervous system. Most skeletal
muscles are attached to bones by bundles of collagen fibres known as tendons.
Skeletal muscle is a highly malleable tissue that is a central factor in whole-body health and the maintenance of
energy homeostasis. Skeletal muscle accounts for approximately 45–50% of body mass and plays a
fundamental role in locomotion, oxygen (O2) consumption, energy metabolism, and substrate turnover and
storage.
Skeletal muscle is responsible for all voluntary movement, and its unique organization is optimized for this
function. Skeletal muscle is a specialized contractile tissue found in animals which functions to move
an organism’s body. Skeletal muscle is comprised from a series of bundles of muscle fibres, surrounded by
protective membranes. This arrangement allows skeletal muscle to contract quickly and release quickly without
subjecting the individual fibres to too much friction. Skeletal muscle tissue can be found across the
animal kingdom, in most multi-cellular forms of life. The classification of the Biceps muscles is shown below
Figure 3: Biceps Muscles
Objectives:
The main objectives of this lab are
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To study the skeletal muscles and its importance in Human Factors.
To understand the structure of skeletal muscles.
To understand the functions of skeletal muscles.
To go through the contraction mechanism of skeletal muscles.
Skeletal Muscle Structure:
Skeletal muscle is comprised of a series of muscle fibres made of muscle cells. These muscle cells are long and
multinucleated. At the ends of each skeletal muscle a tendon connects the muscle to bone. This tendon connects
directly to the epimysium, or collagenous outer covering of skeletal muscle. Underneath the epimysium, muscle
fibres are grouped into bundles called fascicles. These fascicles are surrounded by another protective covering
formed from collagen. The perimysium, as it is called, allows nerve and blood vessels to make their way
through the muscle. The figure 1 given below shows skeletal muscles.
Figure 4: Skeletal muscles
 Each fascicle is formed from tens to hundreds of bundled muscle fibres. Each muscle fibre is formed from
a chain of multinucleated muscle cells.
 These fibres are then protected by another layer called the endomysium as they are bundled into fascicles.
Each muscle cell has distinct regions when viewed under a microscope. These are known as sarcomeres,
and give skeletal muscle a banded or striated appearance.
 Each sarcomere is a complex of proteins, which operates to contract the muscle.
 Sarcomeres are formed from actin and myosin, as well as a number of associated helper proteins. The
filaments seen between the dark bands are actin and myosin filaments.
 Actin, as seen in the image above, is composed of many units of actin and takes the form of a twisting
filament. Actin is accompanied by a number of proteins which help stabilize it and provide a pathway for
muscle contraction. The two most important are troponin and tropomyosin.
 Tropomyosin surrounds the actin filament, and stops the heads of myosin from attaching. Troponin locks
tropomyosin in place until receiving the signal to contract.
 Myosin is a fibre composed of many interlaced tails of individual myosin units. The heads of the units
stick above the fibre and are attracted to the actin filament.
Functions & Contracting Of Skeletal Muscle:
1. When you want to move your arm, your brain sends a nervous signal through your nerves. The simple act
of raising your arm requires many muscles, so the signal is sent down many nerves to many muscles. Each
skeletal muscle receives the nervous impulse at neuromuscular junctions. These are places where nerves
can stimulate an impulse in a muscle cell.
2. Once the myosin heads are attached, the ATP available will be used to contract the filament. This is done
by each pair of myosin heads slowly crawling down the filament. Energy from ATP is used to move
one head, while the other is attached. When many hundreds or thousands of heads are involved, this
quickly contracts the sarcomere up to 70% of its original length.
3. As the nervous impulse hits each muscle fibre and muscle at the same time, the arm can lift in a fluid
motion. As an added feedback measure, every skeletal muscle has special sensory cells which send
feedback to the brain. These cells, called muscle spindles, have specialized proteins which can sense
tension. When tension is received by the cell, the cell starts a nervous impulse and sends the signal through
neurons to the brain.
4. By piecing together this complicated framework of inputs and outputs, the brain can sense where the body
is in space. The somatic nervous system controls these actions, and allows us to move our body in a
coordinated manner. Skeletal muscle is controlled almost exclusively by the somatic nervous system,
while cardiac and smooth muscle is controlled by the autonomous nervous system.
5. This system can be easily demonstrated. Close your eyes, then clap your hands together several times.
Skeletal Muscle Location:
1. Skeletal muscle, as the name implies, is any muscles that connects to and controls the motions of
the skeleton. In all there are somewhere between 600 and 900 muscles in the human body, but an exact
number is hard. Many muscles are obscurely small or are sometimes grouped together with similar
muscles.
2. Skeletal muscle is found between bones, and uses tendons to connect the epimysium to the periosteum, or
outer covering, of bone.
3. Skeletal muscle is adapted and shaped in many different ways, which give rise to complex movements.
Skeletons are not always internal as they are in humans. Even animals with exoskeletons, like crabs and
mussels, have skeletal muscle.
4. While the muscle might be adapted differently depending on the animal, skeletal muscle is defined by its
striations and connections to skeleton.
5. Everything from the flapping of a bird’s wings to the crawling of a beetle are carried out by skeletal
muscle.
Lab Report: 05
To Study the Use of Heat Stress Using Wet-Bulb
Globe Temperature (WBGT) Meter
Introduction:
The wet-bulb globe temperature (WBGT) is a type of apparent temperature used to estimate the effect of
temperature, humidity, wind speed (wind chill), and visible and infrared radiation (usually sunlight) on humans.
It is used by industrial hygienists, athletes, sporting events and the military to determine appropriate exposure
levels to high temperatures.
This meter measures and displays Heat Stress Index (WBGT), which is how hot it feels when humidity is
combined with temperature, air movement, and direct or radiant sunlight. Black Globe Temperature (TG)
monitors the effects of direct solar radiation on an exposed surface.
It also measures air temperature (TA) and Relative Humidity (RH). Additional features include: selectable units
of °F/°C, Auto power off with override, and a built-in RS-232 interface with optional 407752 Windows
software. The Figure 1 given below shows a Wet Bulb Globe Temperature (WBGT) meter.
Figure 5: WBGT Meter
Formula:
It is derived from the following formula:
Were
 Tw = Natural wet-bulb temperature (combined with dry-bulb temperature indicates humidity)
 Tg = Globe thermometer temperature (measured with a globe thermometer, also known as a black globe
thermometer)
 Td = Dry-bulb temperature (actual air temperature)
 Temperatures may be in either Celsius or Fahrenheit
Meter Description:
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1.Black Globe temperature sensor
2. RH and Temperature sensors with protective cover
3. LCD display
4. /SET
5. NEXT
7. RS-232 interface
8. Battery compartment (on rear)
Figure 6- WBGT meter
Symbol
Function
TG
Black Globe Temperature
RH%
Relative Humidity
IN
Outdoor (in full sun)
Low Battery indicator
Symbol Function
TA
Air Temperature
OUT
Indoor (no sun)
C/F
Celsius/Fahrenheit
WBGT
Wet Bulb Globe Temperature
Table 1: Display symbol
Objectives:
The main objectives of this lab are
 To study the Wet Bulb Globe Temperature (WBGT) meter.
 To check the effects of temperature, humidity and direct or radiant sunlight by using Wet Bulb Globe
Temperature (WBGT) measurement.
 Determining the heat stress index, which measures how hot it feels when humidity is combined with
temperature, air movement, and radiant heat.
Procedure:
1. Press the SET button to power the instrument on/off.
2. Slide down the protective sensor cover before taking measurements.
3. Press the MODE button to select the desired display mode: Wet Bulb Globe Temperature
Heat Index (WBGT), Air Temperature (TA), Black Globe Temperature (TG), or Relative
Humidity (RH). An icon will appear in the display indicating the current selection.
4. To select the preferred temperature unit (°F or °C), simultaneously press and release the
MODE and NEXT buttons. The F or C icon will appear in the display.
5. The meter measures WBGT index with (IN) or without (OUT) direct sun exposure. Hold down
the MODE for more than 1 second to alternate between settings. The IN or OUT icon will
appear in the display.
Applications:
 The American Conference of Governmental Industrial Hygienists publishes threshold limit values (TLVs)
that have been adopted by many governments for use in the workplace.
 The heat index used by the U.S. National Weather Service and the humidex used by the Meteorological
Service of Canada, along with the wind chill used in both countries, are also measures of perceived heat
or cold, but they do not account for the effects of radiation.
Observations and Calculations:
Parameters
WBGT(C°)
TG(C°)
TA(C°)
RH (%)
TD(C°)
Inside Lab
16.5
20.9
24.4
31.4
15
Outside Lab
15
22.3
20.9
34
15
Conclusion:
In this lab there is discussion about the WBGT, its specifications, usage, applications and procedure of using it.
From this lab it is concluded that humidity has impact on the temperature which is noted by using the WBGT.
By using WBGT we can determine the heat stress index, which measures how hot it feels when humidity is
combined with temperature, air movement, and radiant heat.
Lab no: 06
Detection of sound level in various
environments with sound level meter
Introduction
Different devices are invented for the advancement and safety of people and its living environment. Similarly, in
this competitive world each firm uses certain standards while performing their job, in which sound standards play
very important role. Sound level meter is a device used for detection and for measuring sound intensity and widely
used in every industry for this specific goal achievement. By reducing noise pollution in workplace, the efficiency
of the workers increases and productivity of the company increase, therefore it plays a vital role in industrial
system.
A digital sound level meter is used for acoustic measurements. The word "acoustic" means "sound that travels
through air". This is opposed to the word "audio", a term that is also often used in the field of sound measurement.
"Audio" refers to sound that travels electronically through cables and audio components. A sound level meter
needs a microphone to measure the changes in air pressure produced by the sound source. The better quality the
microphone, the more accurate the measurements will be. Such measurement microphones are categorized as
Class 1 or Class 2. For many applications a Class 2 microphone, which is slightly less accurate and less pricey
than a Class 1 microphone, is more than sufficient. Class 1 microphones are usually only required when the law
prescribes. Whichever microphone you use, it is important for accuracy that the microphone is correctly calibrated
Objectives
The objectives of this lab are listed below:
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To know about digital sound level meter.
To study the parts of digital sound level meter.
To understand the function of digital sound level meter.
To know about the applications of digital sound level meter.
Sound Meter parts and their functions
Microphone: It used to catch sound for the device.
Power ON/OFF: It is used to stitch on/off the meter.
Range select switch: It used to select low range or high range level.
A/C Frequency Weighting: Use the button switch to select A or C frequency weighting. Use A weighting to have
the meter simulate the response of the human ear for variable response. Select C weighting for flat response
measurements.
LCD Display: It used to display reading.
FAST/SLOW Response Time: Use the response switch to select FAST (0.85 second) or SLOW (1 second)
response time.
Battery Compartment: Use for the safety precaution of the battery
Procedural precautions during using sound meter
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Calibrate apparatus
Don’t use at high temperature and humidity
Keep meter and microphone dry
Avoid vibration while using it
Remove battery when meter is to be stored for longer period of time
Procedure
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Select a suitable range for the noise level.
To get reading, the sound equipment is taken near to the noise.
Set the time weighting. Select SLOW for normal measurements and FAST for checking average levels of
fluctuating noise.
Check the frequency weighting. Slide switches A/C. A is for general sound level measurement and C for
low frequency sound level content.
Readings appear on the screen; these readings continuously change with time.
To get an accurate absolute value we press the ‘max hold’, we get the maximum value noted of all the
changing values on screen.
Average Readings
From three instance readings, average is calculated and shown below
Sources
Class
Lawn
Road
Average Sound Intensity (dB)
63
68
75
Applications
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A Sound Level Meter (SLM) is the basic, hand-held instrument used to measure general area noise levels.
It can use to check noises such as noises from industrial machinery or equipment (i.e., large trucks,
jackhammers), or noise across boundaries, such as noise from a construction site etc.
Conclusion:
We came to know about sound measuring tool.
Lab Report: 07
To Measure the Luminous Level by Digital Light
Meter
Introduction:
A digital light meter is a device used to measure the amount of light. In photography, a light meter (more
correctly an exposure meter) is used to determine the proper exposure for a photograph. The meter will include
either a digital or analog calculator which displays the correct shutter speed and f-number for
optimum exposure, given a certain lighting situation and film speed.
Light intensity affects the way humans live, work and interact. More recently researchers have discovered how
light affects our health and well-being. Research has shown that while standard artificial light meets our visual
needs, it is not sufficient to provide proper biological signals that our bodies and brains need and can even have
a negative impact on our long-term health. The reason being, people now spend the majority of their lives
indoors – we’ve lost our connection to the sun and the solar day and no longer receive the critical light signals
our bodies and brains need to promote better sleep and daytime alertness. We live in indoor environments that
are too dim for our brains to identify as daytime and too bright at night for our brains to recognize as night time.
We’ve lost our tie to our natural circadian cycle.
For example, think about the brightly-lit grocery store you go to late in the evening or the dim lecture hall or
conference room you might spend the middle of your day – this is completely the opposite of the light signals
around which our bodies evolved.
Digital Light meter is shown in the figure 1 below
Figure 7: Digital light meter
Device Description:
1. Sensor cable
2. Analog bar graph
3. Numerical display
4. RANGE button
5. ON/OFF button
6. MAX/MIN button
7. RESET button
8. LCD Backlight button
9. LUX button
10. Fc foot candle button
11. Protective rubber jacket
12. RELATIVE button
13. Data HOLD button
14. PEAK button
15. Photo sensor dome
Objectives:
The main objectives of this lab are
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To know about digital light meter.
To study different types of lights.
To understand the parts of digital light meter.
To understand the functions (procedure) of digital light meter.
Types of Lights:
As a general rule your workplace will have one of three types of light fitting, these are light sources based on
heat know as incandescent, Fluorescent lights and LED’s. Each one of these produces light in a different
manner.
1. Incandescent light is radiated electromagnetic energy that is emitted across all wavelengths, when we see
all wavelengths things appear white. Different temperatures will alter the amount that each wavelength is
used.
2. Fluorescent Lights are technically outside of our visible range, they are ultraviolet and below 400nm.
However, an interaction with a coating on the inside of their tubes makes is visible white light that we can
use.
3. LED lights are a little more complex and achieve white light through a mixture of red, green and blue
LEDS or methods similar to Fluorescents
Parts of Digital Light Meter:
The parts of digital light meter are listed below:
1. LCD Display.
2. Range Button.
3. ON/OFF Button.
4. Peak Hold Button.
5. Lux Selection.
6. Photo Sensor.
7. Sensor Input.
8. Data Hold Button.
9. Max/Min Button.
10. FC Candela Button.
11. Relative Function Button.
Procedure:
Set the function switch to the desired unit of measure; lux or fc and remove the light sensor cover. Hold the
sensor steady or place it in a secure area and allow the sensor to collect light. The light must encompass the
entire sensor. Ensure that the user does not cast a shadow on the sensor dome. The sensor is connected to the
meter by a 4’ (1.5m) cable. While measuring, the sensor can be kept docked on the meter (as it is shipped) or it
may be disconnected and used remotely. Read the illuminance value on the display. If the approximate
magnitude of the light is not known, step through the ranges using the RANGE button until a measurement is
displayed. If x10 appears on the LCD, the meter is in the 20,000 range and the reading must be multiplied by
10. The OL (overload) icon appears if readings are out of range. While taking a measurement, press the HOLD
button to freeze a displayed reading.
Using a digital light meter is the best way to measure light intensity, it gives us the ability to choose the optimal
light intensity for an environment.
Measure Ambient Light in the Room:
To begin, turn off any lighting in the room you’re about to measure. Turn on the light meter to establish
what’s known as the baseline measurement, the ambient light. This means you’re able to see how much
the existing lighting adds to the room once the lights are then turned on.
Turn On The Lights, Take Your Measurement:
From a central area of the space, ensure your light meter is set up to record your new reading.
Remember not to rush – allow the lighting a few moments to reach full brightness.
Note Your Differential Reading:
Simply subtract the ambient light level from the illuminated level known as the differential (or delta)
measurement, this is the amount of light the existing luminaires produce. With this light measurement
unit, you can assess how it compares to the optimal lighting levels required.
Check Other Areas of A Room:
For open office lighting or a corridor, the reading you get from your light meter should, in theory, be
consistent. However, it might be worth checking any potential “blind” spots just to be sure you have
consistency.
Units of Light Meter:
LUX:
Lux is simply the unit of measure used to describe the number of lumens falling on a square foot
(footcandles) or square meter (lux) of a surface. So let’s say you have a light source with 1,000 lumens.
If all of those 1,000 lumens are spread over a surface area of 1 square meter, you’d have an illuminance
of 1,000 lux – i.e. the brightness of an overcast day. But what if we spread this over 10x the area i.e. 10
square meters? Well, the illuminance or lux would decrease to a less intense and dimmer 100 lux. We
use the same approach for footcandles, only our units are lumens per square foot. The reason we
measure light intensity is to ensure a certain “standard” of illumination is met. It makes a valuable
difference for a photographer (whose work is specifically centered on light) as it would in surgical
theater or other indoor environments such as offices.
Footcandle:
A footcandles is a measure of light intensity, it’s the number of lumen per square foot. Now, you might
be thinking we already covered lux, so why add in this metric? Different people use different metrics
and for different reasons. Simply put, where 1 lux equals 1 lumen in a square meter, 1 footcandle equals
one lumen per square foot.
Luminous Flux:
Luminous flux is how to measure the perceived power or total amount of light output from a light
source. When the number of lumens – the unit-amount of visible light a human eye can see, is used to
measure the intensity of a light source. A one-meter sq. surface area is required (lux) to determine the
luminous flux value.
Common Light Measurements:
There are several types of lighting metrics and measurements used in the lighting industry. So far, we’ve
covered measurements related to light intensity – lumens, footcandles and lux.
Examples of common light levels:
1.
2.
3.
4.
5.
6.
7.
Bright Summer Day: 100,000 Lux (~10,000 footcandles)
Full Daylight: 10,000 Lux (~1,000 footcandles)
Overcast Day: 1,000 Lux (~100 footcandles)
Traditional Office Lighting: 300-500 Lux (30-50 footcandles)
Common Stairway: 50-100 Lux (5-10 footcandles)
Twilight: 10 Lux (1 footcandle)
Full Moon: <1 Lux (<0.1 footcandle)
Conclusion:
The conclusion of this lab is that lux meter is very easy to use and very accurate to measure the intensity of light
which helps in determining the amount of light in any work place.