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Projection optical system, magnification projection optical system, magnification projection apparatus, and image projection apparatus

  • US 7,637,618 B2
  • Filed: 09/19/2008
  • Issued: 12/29/2009
  • Est. Priority Date: 02/06/2003
  • Status: Active Grant
First Claim
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1. A projection optical system, comprising:

  • a first optical system including at least one dioptric system and having positive power; and

    a second optical system including one or more reflecting surfaces having power, the second optical system having positive power as a whole,wherein the first and second optical systems are arranged along an optical path defining an upstream-downstream direction in an order described from upstream to downstream on a downstream side of an object surface;

    an object image is temporarily formed as an intermediate image, and thereafter, is formed as a final image; and

    with respect to an optical axis of an optical element positioned at a furthest upstream end of the first optical system and having refractive power, at least one of other optical elements is shifted or tilted.

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