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Two-color photoelectric detectors having an integral filter

  • US 3,962,578 A
  • Filed: 02/28/1975
  • Issued: 06/08/1976
  • Est. Priority Date: 02/28/1975
  • Status: Expired due to Term
First Claim
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1. In a photodetector combination constructed to sense radiant energy in a plurality of wavelength bands, said combination comprising:

  • a first photodetector optimized for response at a first wavelength, said first photodetector constructed to be transparent to a second wavelength that is relatively longer than said first wavelength and with active elements adjacent a first face thereof,a second photodetector optimized for response of said second wavelength, andmeans for mounting said first and said second photodetectors in a cascade wherein illumination is directed onto said first face of said first photodetector,the improvement comprising an integral filter coating formed on a second face of said first photodetector, said second face being opposite said first face and adjacent said second photodetector, said filter coating forming a bandpass radiant energy filter intermediate said first and said second photodetectors, said bandpass being selected to fall within the radiant energy wavelength response of said second photodetector.

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