Looking for circuit to detect laser light


I'm looking for a simple circuit that will detect light from a red laser light source (i.e. a laser pointer). Something as simple as logic 0 or 0V with no light and logic 1 (+5V) with the presence of laser light.


Mike McWhinney

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Some ideas here:

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You can use a light sensor if you have a ADC input, such as a microcontroller. You might want to add a red filter. (a gelatine)

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Maybe... Phototransistor with red lens. Or Cds cell with red lens. Or Photodiode with red lens.

More off-beat ideas... Solar panel with red lens. Thermistor with red lens.

D from BC

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D from BC

Sensitive and fast but needs external circuit (see project referenced above)

Works great and sensitive but slow.

Also works great but takes more laser light and probably needs some gain to work well.

Basically same as photodiode but much less sensitive.

Going to take to REAL laser power to a response here!!

How about Fairchild QSE-156 photosensor? threshold at 25 mw/cm^2

This sounds like a pretty simple project and the purpose has not been stated so it's difficult to tell what is needed. For REAL sensitivity use a photomultiplier tube. And if ambient room light or daylight is a problem I strongly urge the use of not just a RED filter but rather a BANDPASS filter set to the laser wavelength. Go check them out at Edmund Scientific Expensive but worth it. .

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