CCD Imager with multi-spectral capability

A multi-spectral charge coupled device for generating a plurality of signals representative of the spectral content of a stream of photons impinging on the surfact of said device comprising:

• a plurality of adjacent semiconductor layers arranged to generate a hole-electron pair for each photon of said photon stream, said hole-electron pair generated at a mean depth from the surface of said device which is a function of the wavelength of said respective photon;
• first and second collector means arranged to respectively collect said generated holes and electrons, said first and second collector means arranged at different depths from the surface of said device whereby the efficiency of collection of said holes and electrons are respectively different functions of the depth from the surface of said device at which said holes and electrons are generated;
• and
• output means, operatively connected to said first and second collector means for providing output signals representative of said generated holes and electrons whereby said signals are indicative of the spectral content of said impinging stream of photons.