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Variable magnification optical system and projector

  • US 8,254,039 B2
  • Filed: 08/24/2009
  • Issued: 08/28/2012
  • Est. Priority Date: 09/02/2008
  • Status: Active Grant
First Claim
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1. A variable magnification optical system comprising:

  • a reflective optical element having a positive magnification power and configured to be movable relative to an object plane; and

    a refractive optical system configured to form an intermediate image between the object plane and the reflective optical element, the refractive optical system including plural refractive optical elements, wherein a substantially constant magnification of the intermediate image to the object plane is maintained before and after the magnification change applied to an image projected onto a screen by moving at least one of the plural refractive optical elements;

    increasing a distance between the screen and the reflective optical element increases a magnification applied to the image projected onto the screen, and a change in distance between the screen and the reflective optical element, to effect a change in magnification applied to an image projected onto the screen, is substantially the same as a corresponding change in distance between the reflective optical element and the object plane.

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