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Three field of view refractive afocal telescope

  • US 5,229,880 A
  • Filed: 03/09/1992
  • Issued: 07/20/1993
  • Est. Priority Date: 03/09/1992
  • Status: Expired due to Term
First Claim
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1. An infrared refractive reimaging afocal telescope comprising:

  • an objective lens group for receiving and focusing collimated radiation of a viewed object;

    an eyepiece lens group receiving radiation from said objective lens group said eyepiece lens group recollimating and forming an exit pupil;

    said objective lens group and said eyepiece lens group providing a first magnification and field of view; and

    a switch lens group selectively positioned with respect to said objective lens group to receive and transmit said radiation for changing magnification of the telescope and providing two additional fields of view, and at least one optical element of said switch lens group having an optical diffractive surface for correcting chromatic aberration.

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