Light Sensors

Cameras@ LED@ Wearables@ Infra-Red I/O@ Fiber optics

Richard Ottoson says:

...a quick rule of thumb about opto's:

• Photo diodes have about a 1us response time,
• photo transistors have about a 10us response time, and
• photo darlingtons have about a 100us response time.
• CdS (Cadmium Sulfide) photo resistors have about a ___s response time.

These times assume a "reasonable" resistor value. There are amplified optocouplers that are in the 100ns range as well.

Application notes on photodiodes ( A Primer on Photodiode Technology http://www.centrovision.com/tech2.htm has some simple circuits for photodiodes, and tons of nit-picky detail on how they work. Offline as of 2009-06-13 -- has it moved elsewhere? )

Brian Kraut says:

Go to your local disco and theatrical lighting supply store and ask for for a gell sample book. Voila, about 100 different color plastic filters in 1 X 3" size. Some of them even have spectral response graphs for each sheet.

James Newton Says: " For optical interruption sensors, don't forget your standard super low cost "mechanical" mouse! " +

Phototransistors +

"Line Tracking Robot Project" http://www.seas.upenn.edu/~ese111/robot/Robot.html by Sohrab Rabii and Siddharth Deliwala. Shows a complete line-tracking robot circuit, including photosensors, in excruciating detail.

"Visible and Infrared Light Detectors" http://home.cogeco.ca/~rpaisley4/PhotoDetectors.html by Rob Paisley

"Laboratory Fundamentals in Biological Engineering" http://ocw.mit.edu/NR/rdonlyres/Biological-Engineering/20-109Spring-2006/51EE27E4-D56A-4292-BAA3-BAAFE889223D/0/mod3_proto15.pdf shows a simple photosensor circuit, and compares it to much more complicated stuff.

"Simple optical switch" http://www.electronics-lab.com/projects/misc/017/ by Jonathan Filippi

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