What if you used a prism instead of a filter? Then place the
photodetectors at the correct output angle. I'm not that well versed in
optics, so please excuse me if this doesn't really work :)

Josh
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Jon Baker wrote:
>
> 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
>

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