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Author Topic: Which photodiode?  (Read 1477 times)
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What photodiode would be best for getting a good reading from a green laser? I'm currently finding all of the parts for my project, and the site for the lasers I plan to use does not specify a wavelength, only a colour. I don't very well understand the jargon used in the specs, so I was hoping someone here would! The laser will be pointing at this photodiode from no more than a foot or two away, and it's important that they don't pick up anything other than the laser pointing at it. Link to the laser I will likely use: http://www.fasttech.com/product/1088900-new-wish-5mw-green-laser-module The actual laser module I use may change, but it will always be green.
Thanks,
James D.
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Cd-S photocells have peak response to green / green-yellow (as the human eye.)
They have a wide response nonetheless.

Photodiodes are more sensitive still and have even wider "bandwidths".

Then you're using a laser, a high-intensity source, with it.

You're not going to come up with an optical filter that'll radically attenuate all but your desired narrow green wavelength.  (Not inexpensively so, anyway.)

It's possible that you could considerably attenuate, with mylar tape or something, all light (wavelengths) such that only a laser's intensity could get through.
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The green light has a wavelength of about 510 nm. What you ask is which photodiode with peak sensitivity wavelength is 510 nm.

Typical silicon photodiode spectral response



Typical silicon photodiode should be OK at your case.




« Last Edit: April 25, 2013, 09:29:13 pm by sonnyyu » Logged

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Quote
You're not going to come up with an optical filter that'll radically attenuate all but your desired narrow green wavelength.  (Not inexpensively so, anyway.)

It's possible that you could considerably attenuate, with mylar tape or something, all light (wavelengths) such that only a laser's intensity could get through.

Perfect point! special if it is outdoor with directly sunlight.

Plan B.

52MM Goja Full Green Color Filter

Amazon, $5.95
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Well the actual sensor will be covered, but I do wonder if I could just get a strip of the material that's made out of, just to block out all the light that could get in...
Or maybe just get a strip of black fabric that could be stapled in between the laser and the sensor, and the rest enclosed. Then the intensity of the laser could get through, but very little other light
« Last Edit: April 25, 2013, 09:44:53 pm by qazxvy » Logged

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Plan C. matching  pair of photodiode with no attenuate.

Sample:-

MTD5052N

digikey,$7.55


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Well the actual sensor will be covered, but I do wonder if I could just get a strip of the material that's made out of, just to block out all the light that could get in...
Or maybe just get a strip of black fabric that could be stapled in between the laser and the sensor, and the rest enclosed. Then the intensity of the laser could get through, but very little other light

if sun light is really bother you, then UV laser diode and UV photodiode is way to go.



but it is very pricy...
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