Troy Owens, John Trytko, Adam Ornstein, Dmitriy Polyakov, Michael Tanksalvala

 System measures the phase shift of light to determine the concentration of particles in the air
 Light accumulates a media-dependent phase shift as it resonates in the cavity
 Higher concentration of particles induce a larger phase shift
 This is used in conjunction with other instruments to compute specific concentrations of various aerosols
John Dmitriy Michael Adam Troy

Laser
Controller Laser
Ringdown
Cavity
Beam
Splitter
Photodiode
Phase Shift
Detector
Kebabian, Paul L., Scott C. Herndon, and Andrew
Freedman. "Detection of Nitrogen Dioxide by Cavity
Attenuated Phase Shift Spectroscopy." Analytical
Chemistry 77.2 (2005): 725. Print.
John Dmitriy Michael Adam Troy

 Applications:
 Reference for specialized particle-detecting systems
 Measure aerosol content in open air
 Air quality
 Advantages:
 Compact and portable
 Turn-key (no knowledge of instrument required)
 Self-aligning optics
 Autonomous data collection
John Dmitriy Michael Adam Troy

 Low Priority
 Achieve awesomeness – easy with lasers
 Detect phase shift on optical breadboard
 Medium
 Automated laser alignment system
 Data storage
 No use of external lab equipment
 High
 Compact (backpack size) system
 Entirely autonomous (after easy startup)
John Dmitriy Michael Adam Troy

John Dmitriy Michael Adam Troy

 Successful signal detection
 Cavity must establish and maintain an optical standing wave
 Mechanical stability
 Meaningful output from photodiode
 Final output in specified file format
 Time!!!
John Dmitriy Michael Adam Troy

 Environmental impact
 Difficult to dispose of parts
 Beam doesn’t interfere with the environment
 Safety
 Laser can damage eye
 Low power laser
John Dmitriy Michael Adam Troy

 Class IIIa-IIIb (continuous wave, 1 to 20 mW)
 Visible wavelengths (350 – 800 nm)
 Low power/area (< 2 mW/cm 2 )
 Hazards
 Corneal damage only (safe exposure time is roughly .25 seconds)
 Non-permanent retinal damage if viewed for 1 to
2 seconds, permanent viewed for longer
 Do not look into the laser
John Dmitriy Michael Adam Troy

 Manufacturability
 Intended for singular creation
 Mass production unlikely
 Easily portable
 Sustainability
 Low power consumption
 Durable parts and reliable electronics
John Dmitriy Michael Adam Troy

 Laser controller (enabling phase detection)
 Concave mirrors for the cavity
 Controllable mirror mounts (enabling feedback control)
 Beam-splitter
 Photodiode (signal measurement)
 CMOS Camera (sensor for feedback)
John Dmitriy Michael Adam Troy

Laser
Controller Laser
Ringdown
Cavity
Beam
Splitter
Photodiode
Phase Shift
Detector
Image obtained from: http://www.chem.ualberta.ca/~xu/research/crds.htm
John Dmitriy Michael Adam Troy

 Objective: Maintain maximum signal power
 Keeps beam pointed at photodiode using
PID Controller
 If signal is lost, methodically scans over area to try to find it
 Concave mirrors provide small amount of passive beam alignment
John Dmitriy Michael Adam Troy

 Constructed from normal mirror mounts and
(disassembled) piezoelectric buzzers
 Piezoelectric ceramic expands when voltage is applied
John Dmitriy Michael Adam Troy

Laser
Controller Laser
Alignment
System
Beam
Splitter
CMOS
Camera
Micro-
Controller
John Dmitriy Michael Adam Troy

 Create circuit to connect camera to computer
 Helps for debugging during and after development
 Enables good capstone demo
 Add controllable mirror and microcontroller
 Beam-steering functionality
 Software-based PID signal maximization
 Signal-finding
 Add second mirror and integrate it into PID
John Dmitriy Michael Adam Troy

Laser
Controller Laser
Alignment
System
John Dmitriy Michael Adam Troy
Beam
Splitter
Photodiode

 Processing Time
 Camera can output millions of datapoints
 20 MHz processor
 Number of Cameras
 Signal strength at Camera
 Contingency plan: Using concave mirrors provides a self-aligning force, so even without active feedback, measurements can be made
John Dmitriy Michael Adam Troy

 SD Card
 Storage of phase, timestamp, and “valid bit”
 OS Storage (cold-start)
 Clock
 Microcontroller oscillator
 Timestamps
John Dmitriy Michael Adam Troy

Battery
Hardware
Clock
User
Interface
Micro-
Controller
SD
Solid State
Drive John Dmitriy Michael Adam Troy
Phase Shift
Detector

 SD Card
 Storage of phase, timestamp, and “valid bit”
 OS Storage (cold-start)
 Clock
 Microcontroller oscillator
 Timestamps
John Dmitriy Michael Adam Troy

Data Processing Data Formatting Time Management
OS / μC
ADC SD Card
John Dmitriy Michael Adam Troy
Time I/O

SD
John Dmitriy Michael Adam Troy

Task
OS Design and Data Storage
Primary
Adam
All
Michael
Secondary
Michael
Mechanical Structure/Alignment Dmitriy
Control Systems Michael
Power system
Board Layout/Construction
Troy
John, Adam
John
Adam
Troy, Michael
Optical Construction and
Detection
Design Documentation
Chief Financial Officer (CFO)
John Dmitriy
John Dmitriy Michael Adam Troy

John Dmitriy Michael Adam Troy

Equipment
Laser Controller
Laser
Mirror Mounts/Mirrors
Photodiode
1-2 x Beam-Sampler
MSP430
ATMega328
16-Pin AVR Development Board
1-2 x CMOS Camera
1-2 x PCB
Piezoelectric Buzzer
Other
TOTAL
John Dmitriy Michael Adam Troy
Estimated Price
Borrowed from NOAA
Borrowed from NOAA
Borrowed from NOAA
$20
1-2 x $60
$40
$5
$20
1-2 x
$35
1-2 x $60
$5
$100
$345 - $500

 NOAA
 Providing optical parts (mirrors, mounts, laser controller, optical breadboard, laser)
 Will keep the prototype upon completion
 UROP Funding (Pending)
 Up to $1000 funding
 Requires a report upon completion
John Dmitriy Michael Adam Troy

 Not able to integrate OS with Optics
 Will demonstrate the systems separately at
Expo
 Not able to construct casing for a portable device
 Demonstrate the project on separate breadboards at Expo
John Dmitriy Michael Adam Troy

Bob
Carissa
Tom
Alex
Sam
Image obtained from: http://www.picgifs.com/graphics/noahs-ark/
John Dmitriy Michael Adam Troy