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Wide band color correcting infrared lens system

  • US 4,999,005 A
  • Filed: 10/19/1988
  • Issued: 03/12/1991
  • Est. Priority Date: 10/19/1988
  • Status: Expired due to Term
First Claim
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1. An optional system which comprises:

  • (a) an infrared refractive lens triplet having color correcting properties for radiation ranging from about 3.5 to about 12 micrometers, said triplet comprising;

    (b) a first lens having chromic properties corresponding approximately to about 40 <

    V <

    46, where;

    
    
    space="preserve" listing-type="equation">V =(N.sub.D -

         1)/(N.sub.13 -N.sub.3), ps wherein, for said first lens glass;

    ND is the refractive index at 8 micrometers,N13 is the refractive index at 13 micrometers, andN3 is the refractive index at 3 micrometers;

    (c) a second lens comprising germanium; and

    (d) a third lens;

    (e) said triplet of lenses being capable of simultaneously focusing radiation in the 3.5 -≡

    micrometer and the 8 -12 micrometer range for imaging about a single focal plane.

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