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Michael Tanksalvala Dmitriy Polyakov Adam Ornstein Troy Owens John Trytko.

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Presentation on theme: "Michael Tanksalvala Dmitriy Polyakov Adam Ornstein Troy Owens John Trytko."— Presentation transcript:

1 Michael Tanksalvala Dmitriy Polyakov Adam Ornstein Troy Owens John Trytko

2 The system measures the phase shift of light to determine the concentration of particles in the air (higher concentration yields greater phase shift). This is used in conjunction with other instruments to compute specific concentrations of various aerosols. The project is being developed in cooperation with the National Oceanic and Atmospheric Administration (NOAA). Dmitriy John Michael Adam Troy

3 Low Level Detect optical ringdown on breadboard Automatic cavity length adjustment Save data to memory Mid-Level Detect optical phase shift Automatic cavity alignment Time stamped data saved to SD card High Level Build self-contained unit Recreate faster-than-light neutrinos Automatic beam profile correction Dmitriy John Michael Adam Troy

4 Milestone 1 Show ringdown signal on oscilloscope Demonstrate microcontroller-based beam-steering and cavity length adjustment Save sample string to SD card Milestone 2 Demonstrate phase shift detector Automated photo-diode signal maximization Collect and save formatted data to SD card Dmitriy John Michael Adam Troy

5 Demonstration 1 Show output of phase shift detector on oscilloscope Place dry ice near cavity and show phase shift (voltage) increase Remove SD card and plot contained data in MATLAB Demonstration 2 Connect camera to monitor and photodiode to oscilloscope Manually misalign mirrors and watch automatic readjustment Demonstration 3 (if possible) Insert SD card, turn on system, initiate data acquisition Place self-contained unit near dry ice Turn off system, take out SD card, plot data in MATLAB Dmitriy John Michael Adam Troy

6 Class 3b (continuous wave, 50 mW) Visible wavelengths (633 or 680 nm) High power/area (~200 mW/cm 2 ) Precautions Never look into laser Do not open testing area designated by curtain Laser safety signs will be posted Dmitriy John Michael Adam Troy


8 Measure and record phase shift over several hours. Send the photodiode output to the phase shift detector unit. Output the camera data to alignment system. Output phase shift data to the data storage system. Alignment system directly controls mirrors. Data Storage And User I/O Automatic Alignment Atmosphere User Input SD Card SD Card (Data) Clock Display Optical Generation and Signal Detection Dmitriy John Michael Adam Troy

9 ALGN RGBRGB OS SD Dmitriy John Michael Adam Troy


11 Objective: Determine the concentration of aerosol particles within the cavity. Optical system uses amplitude-modulated laser signal within a cavity to determine the phase shift the cavity introduces. Ringdown cavity simulates effective length of several kilometers through the use of highly reflective mirrors. John Dmitriy Michael Adam Troy

12 Laser Controller Input: On if instrument is on. Output: Intensity modulated sine wave (~50 kHz) via laser to cavity and initial phase shift signal to phase shift detector. Testing: Modulating the laser at a low frequency (~1 Hz) will be visible on a matte surface. Higher frequencies can be verified with a photodiode and an oscilloscope. Laser Cavity Resonates laser with two concave mirrors. Outputs ringdown signal to photodiode. Testing: Shine output into photodiode. Connect photodiode to oscilloscope. Measure photodiode output on scope, and look for a quick rise followed by an exponential decay. Dmitriy John Michael Adam Troy

13 Photodiode Input: Laser beam from ringdown cavity, 12 volt bias voltage. Sensitive to both wavelengths we are considering (633, 680 nm) Output: current passed to phase shift detector. Mirror mounts Front: 99.97% reflection, 0.01% transmission. Rear:.2% T Concave mirrors, 1 m focal length, 6.35 mm thick. Input: One 0-30 V signal per quadrant. To turn mirror to the left, apply a positive voltage to the right two quadrants. Testing: Aim laser at mirror mount, with the reflection hitting a far wall. Apply 0 V across one side of the piezo and 30 V across the other. Watch for beam movement. Dmitriy John Michael Adam Troy

14 Phase shift detector Integrates initial phase shift and final phase shift. Input: Photodiode voltage, initial signal from laser controller. Output: Voltage (representing phase shift) to microcontroller. Dmitriy John Michael Adam Troy

15 ALGN RGBRGB Dmitriy John Michael Adam Troy

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

17 CMOS Camera Outputs NTSC Signal on single signal line Output must be separated into red, green, and blue components Signal Extractor Converts single-channel NTSC to three signals with which the microcontroller and monitor can interface Implementation: a quadrature detector Mirror Mount Voltage Amplifiers Input: Microcontroller voltage (0-5 V) Output: Mirror Mount voltage (0-30 V) John Dmitriy Michael Adam Troy RGBRGB

18 Microcontroller 28 x Piccolo C MHz Reads pixel values from signal extractor Thresholded average pinpoints beam location PID Controller aims beam at desired location Simpler algorithms maximize signal strength by optimizing desired beam location. Manual interface to alter desired position and call basic functions John Dmitriy Michael Adam Troy ALGN

19 InitializationInitialization John Dmitriy Michael Adam Troy Photodiode (PD) Voltage > (prev_volts *.9)? Photodiode (PD) Voltage > (prev_volts *.9)? Optimize Beam Position Beam Missing PD? Optimize Cavity Length Beam Sweep Optimize Beam Position prev_volts = PD Voltage Correct Beam Mode

20 Detect the positions of the most intense locations on the beam profile Use lookup table to correlate this to beam mode type and find solution Testing: Connect the camera output to a monitor. Manually induce different beam modes by altering cavity length and alignment, run function, and watch for the beam profile to turn Gaussian. Optimize Beam Position Loop: Bump mirror 1 in last successful direction (end on failed_dir==4) If photodiode voltage decreases, reverse the movement and increment last successful direction and failed_dir. else, failed_dir = 0; Testing: Connect photodiode to multimeter. Point beam at photodiode and run program. Watch for photodiode output increase. Beam Sweep Move mirror 2 (coarse mirror) in grid pattern, searching for a photodiode signal. Stop when signal is found. Testing: Connect photodiode output to multimeter. Turn beam away from photodiode, run the function, and watch for the photodiode output to increase. John Dmitriy Michael Adam Troy

21 Optimize Cavity Length Increase voltage across all quadrants uniformly, searching for a power maximum. If the function finds no oscillatory behavior, the laser is misaligned. Call Beam Sweep. Testing: Manually adjust cavity alignment and length to get good signal. Mess up alignment. Call function and watch photodiode output increase. Beam Missing PD? Goal: see if beam is pointed at photodiode. Essentially the same as Optimize Cavity Length, but alters the cavity length minimally, to test for voltage fluctuations. If the voltage decreases in at least one direction, output false. John Dmitriy Michael Adam Troy

22 ALGN OS SD Dmitriy John Michael Adam Troy

23 Objective: Store data to file in SD Card Reads Timestamp from atomic clock chip Measures phase shift as analog voltage Measures valid bit as analog voltage Stores these to comma-delimited text file,, Dmitriy John Michael Adam Troy

24 ValidPhaseTime File Formatted SD Card Buffer AlignmentADCExternal Clock collectData =START =!STOP START /STOP Dmitriy John Michael Adam Troy

25 InitializationInitialization collectData == START ? SD Buffer Empty? Write to SD Card John Dmitriy Michael Adam Troy New Data? Write to SD Buffer SD Buffer Full? Close File If Open Push Time to LCD SchedulerScheduler

26 Contains files with gathered data Standardized portable memory FAT32 file system John Dmitriy Michael Adam Troy Image obtained from:

27 Antenna Receives Atomic Clock Signal Receiver Decodes Antenna Signal Microcontroller Decoder Outputs time in RS232 John Dmitriy Michael Adam Troy Image obtained from:

28 Inputs Power Switch Start / Stop Button Outputs LCD display – Time Blinking – Not collecting data Green LED – Working Red LED– Error John Dmitriy Michael Adam Troy

29 Laser Controller – 3 V, 50 mA Camera - DC 12 V, 50 mA Photodiode - 12 V, 50 mA Phase Shift Detector - 12 V, 50 mA Microcontroller (2x) - Core Supply: 3.3 Volts, I/O Supply: 1.8 Volts Mirror Mount Voltage Amplifier – 30 V John Dmitriy Michael Adam Troy

30 Phase shift detector doesnt work Plan: Software alternative Not able to integrate OS with optics Plan: demonstrate the systems separately at Expo Beam size too large for camera to measure position Plan: Use quadrant detector Beam power too low For photodiode: Right Bumper to pick up Spartan Laser For camera: Use quadrant detector Complicated OS doesnt work Plan: Use previously-developed simple OS SD card Interface does not work Plan: save to onboard flash memory John Dmitriy Michael Adam Troy

31 TaskPrimarySecondary OS Design and Data StorageAdamMichael Mechanical Structure/AlignmentDmitriyJohn Control SystemsMichaelAdam Power SystemTroyDmitriy Board Layout/ConstructionTroy, MichaelJohn Optical Construction and Detection John, Troy, Dmitriy Design DocumentationAll Chief Financial Officer (CFO)Michael John Dmitriy Michael Adam Troy


33 EquipmentEstimated Price Acquired Laser / Laser ControllerBorrowed from NOAA Testing Version Mirror Mounts/MirrorsBorrowed from NOAA No Optical BreadboardBorrowed from NOAA Yes 5 x Photodiode5 x $30 Testing Version 2 x Beam-Splitter2 x $60 No 4 x MSP4304 x $25 Testing Version 2 x CMOS Camera2 x $35 Yes 3 x PCB3 x $60 No 5 x Piezoelectric Buzzer5 x $5 Yes Conductive Glue$20 No Power Components$50 No 2 x SD Sockets2 x $5 No SD Card$10 No Oscillator$10 No Final Project Poster$50 No Dry Ice$50 No Structure Materials$100 No Other (replacement parts, shipping, etc.)$200 No TOTAL$1145

34 NOAA Providing optical parts (mirrors, mounts, laser controller, optical breadboard, laser) Will keep the prototype upon completion Additional Funding Received $1,000 from UROP Any necessary additional money will be gathered from generous donations from team members. John Dmitriy Michael Adam Troy


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