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Laser pointer 650nm detector

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Pax Writer

New Member
Hello experts

I want to make a small circuit which can detect a standard 650nm laser beam in broad daylight on a certain distance - Preferebly up to 100m (if at all possible). The first step is to find a photo-thingy (transistor, diode...) which detects 650nm and filters out other light.
The help I'm asking for is to figure out whether such a component exists and if any of you have a similar circuit which works, who can guide me a bit.
With regards to the photodetector, I tried looking on Farnell and a few local sites. No luck, though.
Any helt will be appreciated.
Thanks.
 

ericgibbs

Well-Known Member
Most Helpful Member
Hello experts

I want to make a small circuit which can detect a standard 650nm laser beam in broad daylight on a certain distance - Preferebly up to 100m (if at all possible). The first step is to find a photo-thingy (transistor, diode...) which detects 650nm and filters out other light.
The help I'm asking for is to figure out whether such a component exists and if any of you have a similar circuit which works, who can guide me a bit.
With regards to the photodetector, I tried looking on Farnell and a few local sites. No luck, though.
Any helt will be appreciated.
Thanks.

hi,
Get the datasheets for the SFH203 and SFH309 detector diodes.:)
 

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Pax Writer

New Member
Hi Eric and Gerty
Thanks for your help and sorry for the late reply (for some reason, I don't get reply notifications any more).
Anyway, with regards to the broad spectrum photo diodes, you posted, Eric, won't daylight be a problem, considering that it detecs from 400 to 1100nm?

Gerty: Brilliant link, thanks :) It does pose a problem, because I was hoping to make the photo detector small and cheap and, most importantly, able to run on a small battery of sorts, but I'll see what I can work out.
 

ericgibbs

Well-Known Member
Most Helpful Member
Hi Eric and Gerty
Thanks for your help and sorry for the late reply (for some reason, I don't get reply notifications any more).
Anyway, with regards to the broad spectrum photo diodes, you posted, Eric, won't daylight be a problem, considering that it detecs from 400 to 1100nm?

Gerty: Brilliant link, thanks :) It does pose a problem, because I was hoping to make the photo detector small and cheap and, most importantly, able to run on a small battery of sorts, but I'll see what I can work out.

hi,
A common method is to use a light filter for 650nm or/and a tubular collimator.

One of our members use 'sweet' paper wrapper as a simple colour filter.
 

mneary

New Member
I've read differing information regarding the wavelength sensitivity of LEDs. Some sources suggest that they respond to wavelengths near their output wavelength, while others say they respond to any wavelength equal or shorter. (e.g Red LED responds to red, yellow, green, etc.) Has anyone done experiments?
 
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