Selective Photodiode

Oops...I got my color backward...470nm-blue 660nm-red

Try using ordinary LEDs as photo diode. They have an "intregrated" color filter because of their physical function.

- Henry

"v" schrieb im Newsbeitrag news:ANN%g.467589$ snipped-for-privacy@fe08.news.easynews.com...

Not all LED's have good in reverse voltage outputs. You could probably buy filters from Edmund Optics to put in front of the photodiodes.

grge

It would probably be easier to use a full spectrum photodiode and attach different filters to the front.

Custom filters:

Variety of different filters:

Some more:

filters

Or use a prism with some fancy mechanical vernier and make the whole thing tunable :-)

I don't have a US manufacturer handy, but Hamamatsu makes several series of filtered photodiodes.

i.e.

A few months back I read a posting to some analytical group how a guy used an office scanner and a prism to do some pretty sophisticated optical spectrum analyses... or at least was planning to, whatever, sounds like fun either way :-).

Dimiter

------------------------------------------------------ Dimiter Popoff Transgalactic Instruments

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Joerg wrote:

filters

Hello Dimiter,

Yes, you can achieve amazing results with modest means. Remember the days when people made spectrum analyzers from parts of discarded TV sets? I even used its own tube as a display. So I had the biggest honking spectrum display in town. That is, until the day when the flyback transformer went lalaland with an evil hiss and my allowance didn't allow to order a new one :-(

ISTR people were scanning old records (LP etc?) with scanners and converting the tracks to music.

This outfit has what you need for under $20 each:

If you have a more critical application this outfit can custom make anything:

Steve Noll | The Used Hi Tech Equipment Dealer Directory: |

These guys make them:

...jerry