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Motion detector for space surveillance

  • US 4,479,056 A
  • Filed: 05/17/1982
  • Issued: 10/23/1984
  • Est. Priority Date: 05/18/1981
  • Status: Expired due to Fees
First Claim
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1. A motion detector responsive to incident radiation, comprising:

  • an elongate four-sided frustopyramidal box with a first pair of longitudinal walls bisected by a plane of symmetry and a second pair of longitudinal walls converging toward said plane of symmetry from a wider closed end toward a narrower entrance and accessible to incident radiation, at least the walls of said second pair having reflective inner surfaces;

    a concave radiation reflector at said closed end with a vertex in said plane of symmetry and a focus near said entrance end; and

    radiation-sensing means in the vicinity of said focus confronting said concave reflector for illumination by incident beams of parallel rays approaching said entrance end at a plurality of predetermined azimuthal angles with reference to said plane of symmetry and reflected at least once in said box by a wall of said second pair, said radiation-sensing means having a receiving area substantially narrower than said entrance end at least in a direction perpendicular to said plane of symmetry, the length of said box being so related to the angle of convergence ∝

    included between said second pair of walls and said plane of symmetry that incoming beams traversing said entrance end at azimuthal angles ±

    (2n+1)·

    α

    undergo n reflections at said second pair of walls before reaching said concave reflector, n being an integer ranging from 0 to a maximum of 3, said incoming beams being converted by said concave reflector into converging beams undergoing each a further reflection at said second pair of walls before impinging from different directions onto said radiation-sensing means.

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