I am working on a similar but slightly more complex project at the moment which needs to detect 4 different wavelengths of light emitted from a sample luminescing. The amplitude ( brightness??) of the light at each frequency must be measured independently so I can draw 4 graphs- each frequency corresponds to a particular molecule and the graph is to show the concentrations ( brightness ) with time of each. I am positive this can't be done with filters over photo detecetors becuase the number of photons I need to detect is so small it would be absorbed into the filter. What would be ideal is a several photodetectors each of which is sensitive to a (different) narrow band of wavelengths. Does anyone have any pointers where I could look for such specific devices? I had thought of using a CCD, but with all 4 wavelengths being measured by the same device I think it would be almost impossible to extract the 4 sets of data I need from the RGB value the CCD would give me. Any help much appreciated. -- Jon Baker ----- Original Message ----- From: "Vitaliy Maksimov" To: Sent: Wednesday, January 16, 2002 2:16 PM Subject: Re: [ot]: > > Hi guys. I have a question. > > > > I have an LED that lights 3 different colors :red, green and ambar, I > would > > like to know what kind of sensor I could use to detect the 3 colors emited > > from the LED. > > I believe that amber is the combination of red and green. You could use two > photoelements with different color filters (red & green). Then, if you get > a HIGH from the "red" sensor, and LOW from the "green" sensor, you could > safely assume that the color of your LED at this given time is red. Same > thing for green. And if *both* sensors give you a HIGH, the color is amber. > > Hope this helps, > > Vitaliy > > -- > http://www.piclist.com hint: To leave the PICList > mailto:piclist-unsubscribe-request@mitvma.mit.edu > -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu