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Objective lens system for endoscopes

  • US 4,493,537 A
  • Filed: 11/04/1982
  • Issued: 01/15/1985
  • Est. Priority Date: 11/10/1981
  • Status: Expired due to Fees
First Claim
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1. An objective lens system for endoscopes comprising a first negative meniscus lens component having a concave surface on the image side, an aperture stop, a second positive meniscus lens component, a third biconvex lens component and a fourth positive cemented doublet component consisting of a positive lens element and a negative lens element, said lens system being so designed as to satisfy the following conditions:

  • ##EQU2## wherein the reference symbol f represents total focal length of the entire lens system as a whole, the reference symbol f234 designates total focal length of said second, third and fourth lens components as a whole, the reference symbols r2 , r5 and r7 denote radii of curvature on the image side surface of said first lens component, image side surface of said second lens component and image side surface of said third lens component, the reference symbols n1 through n5 represent refractive indices of the respective lens elements and the reference symbols ν

    1, ν

    2 and ν

    3 designate Abbe'"'"'s numbers of said first, second and third lens components respectively.

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