Insect Photography Rig – MDR

1. Insect Photography Rig –MDR Team Fischetti: Nafis Azad Brendan Kemp Rob Leveille

2. A Beautiful Day in a Field of Flowers – A Scenario • You want to take pictures of the flying bugs • But they move too fast • Your reaction time isn’t fast enough • Your camera’s reaction time isn’t fast enough • It has to calculate several variables • Aperture • Shutter Speed • Focal Length • The mechanical adjustments take too long • You need a way to bypass human and machine…

3. The Insect Photography Rig • Will bypass the human aspect • Insect trips a laser when it is in the frame • Will bypass the machine aspect • All variables are preset • No calculations or adjustments need to be done • Just hold the rig where insects will fly • The insect will trip the laser when it is perfectly in place • The camera will be preset, in manual mode • Our circuitry commands the photo • How do we do it?

4. Outline • The Problem – A Photography Scenario • The Solution – The Insect Photography Rig • The Design • Frame and Sensors • Logic and IR Transmitter • IR Transmitter and Camera • The Challenges • Past: Timing, Logic, Remote • Present: Working Prototype • Future: Intersection Probability, Response Time, Frame, Laser Shutoff

5. Design Overview • Lasers and Sensors • Produce low when broken • Crisscross to triangulate • Create “mesh” of points • Output to logic • Logic Circuitry • Finds coincidence – AND • Sends signal to transmitter • Transmitter sends IR signal • Camera • Snaps photo

6. Frame and Sensors – Design • Frame consists of base to securely attach the camera, two arms extending to the left and right of focal plane, and vertical mounts for the laser/sensor pair • Laser beams cross in the focal plane of the camera detect when an insect is in position • Sensor information is processed and communicated to camera via Nikon IR transmitter

7. Logic and IR Transmitter – Design • During standby mode all photodiodes are collecting light from the lasers, producing a high logic on the inputs to the NAND gate • When a beam is broken an input of the NAND goes low thus producing a high logic at the output • When two intersecting beams are broken both NAND gates are pulled to high logic and the IR transmitter is turned activated

8. Circuit Diagram – One More Time

9. IR Transmitter and Camera – Design • The IR transmitter (shown below) was taken apart in order to be able to control it using the coincidence circuitry. • The button initiating the IR sequence to the camera is shorted and leads to the battery are now connected to a PMOS switch. • Once the coincidence circuitry has detected an object in the focal plane the IR transmitter is temporarily turned on via the PMOS switch which sends the IR signal to the camera. • The camera receives the signal and closes the shutter, snapping a picture of the insect.

10. Outline • The Problem – A Photography Scenario • The Solution – The Insect Photography Rig • The Design • Frame and Sensors • Logic and IR Transmitter • IR Transmitter and Camera • The Challenges • Past: Timing, Logic, Remote • Present: Prototype • Future: Intersection Probability, Response Time, Frame, Laser Shutoff

11. Timing – Past Challenges • Need accurate measurement of lag • Ensure specifications, optimize design • Timing events within .5 second • Need microcontroller and two electric signals (start & stop) • Start signal is easy • Use the photodiode signal • Stop is harder • Time when light is transmitted to chip • Mechanical process – electronics internal

12. Timing – Past Challenges • SLR – Single Lens Reflex • Scene through lens is reflected to viewfinder • On capture, mirror snaps up blocking viewfinder • Laser into lens, out viewfinder, into photodiode • Don’t want to fry the camera sensor • Laser into viewfinder, out lens, into photodiode • Added benefit of variable focal length from lens • Hook both photodiodes to microcontroller • Insect one starts counter, lens one stops • Use interrupt based negedge detection • Output to LED bar

13. Logic – Past Challenges • Original design was microcontroller • Obvious, but necessary? • Just want coincidence circuitry • Can be accomplished with logic – NAND gates • Faster and more elegant • Problem of interfacing photodiode to gate • Too much voltage with ambient light • Logical low was not registered • Reduce operating voltage • Registers high and low

14. The Prototype • MDR Specs • Laser Trip System • Shutter trip • Timing System

15. The Working Prototype: Part II • Laser/Sensor Pairs • 5mW Keychain lasers • Photodiode with sufficient sensitivity to red light (650 nm λ) • Prototype of Mounting Rig • Two arms complete with mounts for laser and sensor pairs • Lasers are to cross in the focal plane of the camera • Sensing Circuitry • Coincidence circuit detects presence of insect within the focal plane of the camera • System lag circuitry • Microprocessor is used to test the lag of the system

16. Outline • The Problem – A Photography Scenario • The Solution – The Insect Photography Rig • The Design • Frame and Sensors • Logic and IR Transmitter • IR Transmitter and Camera • The Challenges • Past: Timing, Logic, Remote • Present: Working Prototype • Future: Intersection Probability, Response Time, Frame, Laser Shutoff

17. Intersection Probability – Future Challenges • What is the probability an insect will just fly through? • Randomly: infinitesimal • Fortunately, not random: traffic patterns, flowers • What can we do to increase our chances? • Our capture area is limited by the camera’s specs • Add more detection points • Crisscross ‘net’ of 6 lasers, 6 sensors • Ensure maximization of capture probability • Will be difficult to fit, physically

18. Frame – Future Challenges • Requirements: light, stable, space constraints • Needs to be worn with shoulder strap • Usage could be fatiguing on its own • Minimal warping: 1mm^2 photodiode target • Real world stresses – don’t want to recalibrate • Needs to hold ungainly laser pointers securely • Need to fit 6 photodiode/laser pairs • The prototype is already crowded • Needs to be adjustable for lenses, focal lengths • Allow for flexibility, other lenses and camera bodies

19. Response Time – Future Challenges • We believe our timing optimizations are sufficient • Not yet field proven • Our main sources of lag are transmit and mirror • IR transmit: .150 seconds • Mirror/camera: ~.2 seconds • Logic: 2 microseconds • Use a secondary shutter • Leave the main shutter open and ready • Use logic to drive secondary shutter • Response time on magnitude of microseconds

20. Laser Shutoff – Future Challenges • Lasers are great for detection, attracting insects • They aren’t aesthetically pleasing • We need a way to shut them off • Start with integrating power source • Dismantle case and wire leads to main source • Use logic to control laser power • Ready mode: lasers on • Photo snap: lasers off • Back to ready mode • Use logic command to drive transistor

21. Conclusions • The Problem – A Photography Scenario • The Solution – The Insect Photography Rig • The Design • Frame and Sensors • Logic and IR Transmitter • IR Transmitter and Camera • The Challenges • Past: Timing, Logic, Remote • Present: Prototype • Future: Intersection Probability, Response Time, Frame, Laser Shutoff • Questions?