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2009 Olin Student Projects. Keith Gendreau Keith.c.gendreau@nasa.gov 301-286-6188 Phil Deines-Jones philip.v.deines-jones@nasa.gov 301-286-6884 Jeff Livas Jeffery.livas@nasa.gov 301-286-7289. 2009 Student Projects with contacts. Continuation of MCA Keith Gendreau

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2009 Olin Student Projects


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    1. 2009 Olin Student Projects Keith Gendreau Keith.c.gendreau@nasa.gov 301-286-6188 Phil Deines-Jones philip.v.deines-jones@nasa.gov 301-286-6884 Jeff Livas Jeffery.livas@nasa.gov 301-286-7289

    2. 2009 Student Projects with contacts • Continuation of MCA • Keith Gendreau • XACT Sounding Rocket Optical Bench Alignment System • Keith Gendreau, Phil Deines-Jones • UV flux monitor • Keith Gendreau • Super Webcam microscope • Jeff Livas • USB Bit Error Rate Measuring Tool • Jeff Livas

    3. Continuation of MCA project from 2008 • In 2008, I asked the Olin students to make a “$25 MCA” to measure pulseheights and record times of X-ray events from a detector. • System nearly worked, but not quite…

    4. A PIC Microcontroller Based Pulse Detection and Measurement System Take an input analog signal, look for pulses above a threshold, detect the peak voltage of each pulse, digitize the peak voltage, write to a file the pulse time and peak pulse height, continue…. Build on last year’s “Flux Meter”, if possible.

    5. X-ray Detection and Pulses X-ray photons Vsignal X-ray Detector Amplifier X-rays pack a lot of energy. X-ray detectors see individual X-ray photons. If the detectors and electronics are good enough, they can determine the energy of the photon. Science is to be gained by knowing the energy of the photons and when they arrived.

    6. Pulses on an analog signal (from an X-ray detector) V vpulse Vpulse is proportional to Energy of photon Pulse widths: ~25 ns- 2µsec t tpulse V Noise pulses? vthresh t Pulse#1 Pulse#2 Pulse#3

    7. Desired Layout: Top view Computer With Olin Software To display/save Events Olin Pulse Height Box Analog signal From X-ray Detector On a BNC Connector USB Output Any type of computer, PC or Mac (I prefer Mac, but whatever is doable) Knob for Lower Voltage Threshold Knob for Additional gain

    8. Requirements • Must handle pulses ranging from ~< 100 nsec to ~ 100 microsec wide • Loosen requirement: Require 1-50 microseconds with a goal of 100 nsec to 100 microseconds • Goal of achieving ~106 counts per second (typically, it is much less than this, I’d be happy with ~104 cps) • Loosen requirement to ~1000 cps with a goal of 105 cps • Should be able to handle pulseheights ranging from ~0 to 10 volts (positive).

    9. Output Desires • ASCII file with time and pulseheight for each event above threshold • Plot with histogram of pulseheights • Flux vs time (like on the flux meter) • Be creative. • TCP/IP port? • eg, The computer reading the instrument can make the data available as a server to others as client computers via a TCP/IP Sockets protocol • Would be an extremely useful feature for beamline work.

    10. For 2009 • I will send you home with a detector • We could not get the software to work from last year. • Last year’s board broke at the USB connection and we now have a flaky USB board on one of our computers… (QA)

    11. Project #2, XACT Optical Bench Alignment • We are in the initial phases of designing and building a suborbital rocket payload to do astrophysics • Science is realized when optics can direct photons to detectors about 3 meters away. • An optical bench separates the optics and the detectors… • Can we measure the relative alignment of these? • Tip/Tilt and X/Y offsets

    12. XACT Payload and Rocket Nose Cone & Recovery System X-ray Polarimeters, Electronics, & MXS Telemetry and ACS Systems Aft Cone & Door Optical Bench Black Brant VC X-ray Concentrators & Star Tracker Terrier Mk70 Overall Payload Length: 3.26 m Payload Diameter: 52 cm* Payload Mass: 80.2 kg (include ST) A 1st approximation of complete XACT rocket

    13. Alignment • X-ray optics must not shift laterally more than ~1 mm from a line connecting the source to the detector • Measure to 0.1 mm • Optics must not tilt relative to detector more than ~ 2 arcminutes • Measure to 1/5 arcminute

    14. Laser Position Sensitive Photodiodes BeamSplitters

    15. Laser Lateral Shift Part Position Sensitive Photodiodes BeamSplitters Tilt Part

    16. Components • Position Sensitive Photodiodes • Produces analog voltage proportional to position of light centroid • Made by Pacific Silicon Sensor • Laser • Mirrors • Beamsplitters • “the Smarts” • Combines the outputs of the photodiodes and puts out 4 types of data: X and Y offset, Tip and Tilt angle

    17. I’ll give you these as well as a laser and some optics…

    18. Olin Student Job for XACT Alignment System • Design full system- including the “smarts” • Build a prototype system using two optical benches separated by ~ 3 meters • Test • Document

    19. Olin student Project #4: UV flux monitor • Our new modulated X-ray source uses UV light to generate photoelectrons which are accelerated into high voltage targets to make X-rays • We like to have absolute control of the X-ray flux, which is driven by absolute control of the UV light (from LEDs) • We have found some evidence of UV LED instability • Need a way to monitor UV flux and record it on a computer with time stamps.

    20. The World’s First Fully Controllable Modulated X-ray Source • Characteristics: • Rugged- no moving parts or fragile filaments- perfect for space flight. • Modulates x-rays at same rate that one can modulate an LED • Major NASA Uses: • Timing Calibration • A “flagged” in-flight Gain Calibration Source: Have calibration photons only when you want them and increase your sensitivity by reducing the background associated with the calibration photons

    21. Unpolarized MXS Prototype for XACT HV FEED- THROUGH QUARTZ WINDOWS (2) BE WINDOW UV LEDs

    22. ~3 days

    23. Computer which reads and records data at regular intervals, or at times when there is a change. Electronics with a UV photodiode (Mouser has several) and circuit to read it. USB

    24. Objectives for Olin Summer UV Flux monitor Project 2009 • Design and build UV Photodiode circuit • Build a USB interface • Write software to record data- perhaps triggered by changes in flux • Calibrate

    25. Olin student Project: $75 Diffraction-limited microscope “Simple” Microscope webcam Protective tube Single lens

    26. Olin student Project: $75 Diffraction-limited microscope “Compound” Microscope: 2 lenses Webcam: pixel size will limit resolution Add on another Single lens And maybe a support tube

    27. Olin student Project: $75 Diffraction-limited microscope • Requirements • Approximately 1 micron resolution (~ 2 !) • Reasonable working distance (~ 10 mm) • Built-in calibration capability?

    28. Olin student Project: $75 Diffraction-limited microscope • Tasks • Figure out single lens focal length • Work out required additional lens • Figure best-possible resolution based on number of pixels, diffraction, etc • Prove it! • http://en.wikipedia.org/wiki/1951_USAF_Resolution_Test_Chart

    29. 0.005” = 127 m Olin student Project: $75 Diffraction-limited microscope • Out of the box: • Roughly 5 mils is easy • 1.3 Mpixel is 640 x 480 color • 640 x 480 x 4 = 1.3 Mpixels • From picture • guess 127 um is 1/10 x 480 = 48 pixels, or 2.6 pixels/micron (color) Shim stock on edge

    30. Olin Objectives for Microscope Project: • Design add on optic for current microscope • Build and Test • Update software to transfer calibration to images

    31. Olin student Project: Bit Error Rate (BER) Test System • Idea: quantitatively measure the performance of a comm link • Concept: Go digital! • Send a pattern out with the transmitter • At the receiver, recover the pattern • May be difficult to find if many errors • Overall time shift not important • May be inverted • Count the errors • Accumulate statistics on type of error, etc

    32. 1 0 0110010111 1 Error  0 Error Olin student Project: Bit Error Rate (BER) Test System Error types Clock Rx • Concept: Go digital! • Send a pattern out with the transmitter • At the receiver, recover the pattern • May be difficult to find if many errors • Overall time shift not important • May be inverted • Count the errors • Accumulate statistics on type of error Tx Transmitter Noisy Channel Noise Receiver 0110010101 Clock recovery

    33. 1 0 0110010111 1 Error  0 Error Olin student Project: Bit Error Rate (BER) Test System Error types Clock Rx • Concept: Go digital! • Send a pattern out with the transmitter • At the receiver, recover the pattern • May be difficult to find if many errors • Overall time shift not important • May be inverted • Count the errors • Accumulate statistics on type of error Tx Transmitter Noisy Channel Noise Receiver 0110010101 Clock recovery

    34. Block Diagram Olin Electronics box that produces test pattern and sends it out a BNC. Box also has a BNC for the receive end Computer with Olin Student software that prepares the test pattern for transmission, issues transmit command, and compares received to transmitted. Finally produces a BER figure USB BNC In BNC out “comm Link”

    35. Olin student Project: Bit Error Rate (BER) Test System • Tasks • Choose test patterns, build generator • Develop clock recovery (PLL) • Develop “pattern recognition” • Cross-correlation based often best • Time shift by bits to find best fit • Accumulate error statistics • BER = number of errors/total bits sent

    36. Projects we probably wont do this year

    37. “i-Heliograph” • Can we make a low power data transmitter to send “lots” of data from the moon to the earth using a 19th century idea enhanced with 21st century technology? • How does such a system compare to laser communication?

    38. Replace this guy with a avalanche photodiode and an ethernet port.. Replace this guy with a high speed optical modulator and an ethernet port.

    39. Replacing the guy wiggling the mirror • Voltage Controlled LCD displays (KHz Speeds?) • Acoustic Optical Modulators (speeds up to 100 MHz)

    40. Replacing the guy using his eye to see the signal on the receive end • Avalanche Photo diodes

    41. There should be a power savings compared to Laser Comm • Lasers are ~10% efficient on producing optical output from electricity it gathers from ~25% efficient solar cells. • Total efficiency from sun = 0.25 * 0.1 = 2.5% • Mirrors are ~90% reflective

    42. Other factors in comparison • Mass to moon • Do solar cells and power system with Laser weigh more than a mirror and heliostat? • Reliability • Solar panels, motors, AOMs… • Is dust an issue?

    43. 2009 Olin Job • Build a Heliostat to capture the sun • Pipe the light from the Heliostat through either an accoustic optical modulator or a LCD retarder • Build a simple pulse frequency modulator to drive the AOM or LCD retarder • Build a demodulator to read the output of an APD • Predict performance and compare to Laser Comm.

    44. GSFC will provide • A telescope base to make a heliostat • An AOM to modulate light • A Circuit design to produce a FM Pulse train • A Telescope for the receive end • An APD (maybe dual use the one for the MCA project) • The demodulator design.

    45. Olin student Project: Laser Ranging System

    46. Lunar Laser Ranging Background • First suggested by R. H. Dicke in early 1950s. • MIT and soviet Union bounced laser light off lunar surface in 1960s. • Retroreflectors proposed for Surveyor missions but not flown. • Retroreflectors flown on 3 Apollo missions.

    47. Science of LLR Lunar ephemerides are a product of the LLR analysis used by current and future spacecraft missions. Lunar ranging has greatly improved knowledge of the Moon's orbit, enough to permit accurate analyses of solar eclipses as far back as 1400 B.C. Gravitational physics: Tests of the Equivalence principle Accurate determination of the PPN parameter β,γ, Limits on the time variation of the gravitational constant G, Relativistic precession of lunar orbit (geodetic precession). Lunar Science: Lunar tides Interior structure (fluid core)

    48. Optical Communications With an optical link it is natural to use it for communications in addition to ranging. Potentially higher capacity over large distances than RF communications. Several methods currently under development at GSFC.

    49. Other applications Collision avoidance Robotics Delay estimation