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Vari-focal image pickup optical system for endoscopes

  • US 5,933,282 A
  • Filed: 06/05/1997
  • Issued: 08/03/1999
  • Est. Priority Date: 06/06/1996
  • Status: Expired due to Term
First Claim
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1. A vari-focal image pickup optical system for endoscopes which is to be used in a condition attached to an eyepiece of an endoscope comprising, in order from the object side:

  • a first focusing lens unit which is capable of adjusting a diopter within a range covering positive and negative values, and has a positive refractive power;

    a second variator lens unit which has a vari-focal function and a negative refractive power; and

    a third compensator lens unit which corrects a deviation of an image location caused by changing a magnification,wherein magnifications of said second lens unit and said third lens unit are changed around -1×

    ,wherein a magnification of said optical system is changed from that at a wide position to that at a tele position by moving said second lens unit from the object side toward the image side and moving said third lens unit from the image side toward the object side, andwherein said third lens unit is set at a magnification of -1×

    when said second lens unit is set at the magnification of -1×

    during a change of the magnification of said optical system.

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