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Apparatus for image multispectral sensing employing addressable spatial mask

  • US 5,867,264 A
  • Filed: 10/15/1997
  • Issued: 02/02/1999
  • Est. Priority Date: 10/15/1997
  • Status: Expired due to Fees
First Claim
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1. An apparatus for measuring the spectral composition of light emanating from a remote target comprising:

  • (a) an input optical element adapted to receive and transmit said light emanating from a remote target; and

    (b) a diffractive optical element having an optical axis and disposed to receive said light transmitted by said input optical element and adapted to disperse spectral components of said light into a volume having an area A and a length L; and

    (c) an addressable spatial mask disposed between said input optical element and said diffractive optical element comprising a sheet having a planar array of discrete addressable switchable apertures disposed thereon, said apertures being independently operable for directing a controllable portion of said light incident thereon to said diffractive optical element in response to a control signal; and

    (d) a photodetector array with pixels having an area substantially equal to the pixel footprint at the addressable mask, said photodetector array being disposed to receive dispersed light from said diffractive optical element; and

    (e) means for measuring said controllable portion of said light that is focused upon said photodetector array, said measured controllable portion comprising an image; and

    (f) means for changing the distance between said diffractive optical element and said photodetector array in the direction of L; and

    (g) means for controlling the direction of said light incident upon each of said plurality of apertures of said addressable spatial mask to impinge upon said diffractive optical element; and

    (h) means for measuring said distance between said diffractive optical element and said photodetector array;

    said spectral composition of light emanating from said remote target being determined by combining the images for each position along L.

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