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

OPEN-ATMOSPHERE PHASE-SHIFT CAVITY RINGDOWN INSTRUMENT

NOAA’S ARK

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

CONCEPTUAL BACKGROUND

System measures the phase shift of light to determine the concentration of particles in the airLight accumulates a media-dependent phase shift as it

resonates in the cavityHigher 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

PhotodiodeBeam Splitter

Ringdown Cavity

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.

APPLICATIONS AND ADVANTAGES

Applications:Reference for specialized particle-detecting systemsMeasure aerosol content in open airAir quality

Advantages:Compact and portableTurn-key (no knowledge of instrument required)Self-aligning opticsAutonomous data collection


GOALS

Low PriorityAchieve awesomeness – easy with lasersDetect phase shift on optical breadboard

MediumAutomated laser alignment systemData storageNo use of external lab equipment

HighCompact (backpack size) systemEntirely autonomous (after easy startup)


FUNCTIONAL OUTLINE OF APPROACH

Pow

er

Battery

Optics

Operating System

CMOS Camera

Alignmentμ-Controller

Photo DiodeA/D

SD CardUserI/O

Clock


CONSTRAINTS

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!!!


SAFETY AND ENVIRONMENTAL IMPACT Environmental impact

Difficult to dispose of partsBeam doesn’t interfere with the environment

SafetyLaser can damage eyeLow power laser


LASER SAFETY

Class IIIa-IIIb (continuous wave, 1 to 20 mW)Visible wavelengths (350 – 800 nm)Low power/area (< 2 mW/cm2)

HazardsCorneal damage only (safe exposure time is

roughly .25 seconds)Non-permanent retinal damage if viewed for 1 to

2 seconds, permanent viewed for longerDo not look into the laser


MANUFACTURABILITY AND SUSTAINABILITY

Manufacturability Intended for singular creationMass production unlikelyEasily portable

SustainabilityLow power consumptionDurable parts and reliable electronics


DETAILS OF DESIGN

THE OPTICS

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)




Ringdown Cavity



Image obtained from: http://www.chem.ualberta.ca/~xu/research/crds.htm

ACTIVE FEEDBACK/ALIGNMENT

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


CONTROLLABLE MIRROR MOUNTS

Constructed from normal mirror mounts and (disassembled) piezoelectric buzzers

Piezoelectric ceramic expands when voltage is applied



Beam Splitter

Alignment System

CMOS Camera

Micro-Controller


CONSTRUCTION AND TESTING

Create circuit to connect camera to computerHelps for debugging during and after

developmentEnables good capstone demo

Add controllable mirror and microcontrollerBeam-steering functionalitySoftware-based PID signal maximizationSignal-finding

Add second mirror and integrate it into PID




Alignment System


OBSTACLES

Processing TimeCamera can output millions of datapoints20 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


OPERATING SYSTEM AND μC

SD CardStorage of phase, timestamp, and “valid bit”OS Storage (cold-start)

ClockMicrocontroller oscillatorTimestamps


Operating System

Battery

UserInterface

HardwareClock

Micro-Controller


Solid StateDrive

SD


OPERATING SYSTEM AND μC

SD CardStorage of phase, timestamp, and “valid bit”OS Storage (cold-start)

ClockMicrocontroller oscillatorTimestamps


OS I/O AND FUNCTIONS

ADC SD Card Time I/O

Data Processing Time ManagementData Formatting

OS / μC


Operating SystemSD


DIVISION OF LABORTask Primary Secondary

OS Design and Data Storage Adam Michael

Mechanical Structure/Alignment Dmitriy John

Control Systems Michael Adam

Power system Troy

Board Layout/Construction John, Adam Troy, Michael

Optical Construction and Detection

John Dmitriy

Design Documentation All

Chief Financial Officer (CFO) Michael


SCHEDULE


BUDGET Equipment Estimated Price

Laser Controller Borrowed from NOAA

Laser Borrowed from NOAA

Mirror Mounts/Mirrors Borrowed from NOAA

Photodiode $20

1-2 x Beam-Sampler 1-2 x $60

MSP430 $40

ATMega328 $5

16-Pin AVR Development Board $20

1-2 x CMOS Camera 1-2 x $35

1-2 x PCB 1-2 x $60

Piezoelectric Buzzer $5

Other $100

TOTAL $345 - $500


FUNDING AND GRANTS

NOAAProviding optical parts (mirrors, mounts,

laser controller, optical breadboard, laser)Will keep the prototype upon completion

UROP Funding (Pending)Up to $1000 fundingRequires a report upon completion


POTENTIAL ISSUES / CONTINGENCY PLAN Not able to integrate OS with Optics

Will demonstrate the systems separately at Expo

Not able to construct casing for a portable deviceDemonstrate the project on separate

breadboards at Expo


QUESTIONS?


Alex

TomBob

Sam

Carissa

Image obtained from: http://www.picgifs.com/graphics/noahs-ark/

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

Documents

michael tanksalvala

dmitriy polyakov

adam ornstein

john trytko

troy owens

phase shift of light

larger phase shift

mediadependent phase