Team Fischetti

Insect Photography Rig –

MDRTeam Fischetti:

Nafis AzadBrendan Kemp

Rob Leveille

2Team Fischetti

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…

3Team Fischetti

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?

4Team Fischetti

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

5Team Fischetti

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

6Team Fischetti

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

7Team Fischetti

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

8Team Fischetti

Circuit Diagram – One More Time

9Team Fischetti

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 closesthe shutter, snapping a picture of the insect.

10Team Fischetti

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

11Team Fischetti

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

12Team Fischetti

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

13Team Fischetti

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

14Team Fischetti

The Prototype

MDR Specs• Laser Trip System• Shutter trip• Timing System

15Team Fischetti

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

16Team Fischetti

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

17Team Fischetti

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

18Team Fischetti

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

19Team Fischetti

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

20Team Fischetti

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

21Team Fischetti

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?