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Optical system and visual display apparatus

  • US 5,654,828 A
  • Filed: 10/06/1995
  • Issued: 08/05/1997
  • Est. Priority Date: 10/07/1994
  • Status: Expired due to Term
First Claim
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1. An optical system comprising:

  • a partial optical system having at least two semitransparent surfaces which are disposed so that each semitransparent surface transmits light rays at least once and reflects them at least once;

    a refracting optical element having refractive power; and

    wherein a semitransparent surface of said partial optical system which is closer to a pupil plane is a flat surface, and a semitransparent surface of said partial optical system which is closer to an image plane is a concave surface, and wherein said refracting optical element is disposed at the pupil plane or image plane side of said partial optical system with an air spacing provided therebetween, said refracting optical element having a focal length which satisfies the following condition;

    
    
    space="preserve" listing-type="equation">f.sub.a >

    0where fa is a focal length of said refracting optical element.

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