Image projection optical system and image projection apparatus

Details Image projection optical system and image projection apparatus Image projection optical system and image projection apparatus

2008-03-27

2009-06-09

Sugarman, Scott J (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S676000, C359S683000

Reexamination Certificate

active

07545578

ABSTRACT:
An image projection optical system introduces light from an image-forming element by a zoom lens via an optical element. The optical element satisfies Σ(Di×Ndi)/fw>4.0. The zoom lens includes, in order from a magnification side, first and second lens units, and lens units disposed closer to a reduction side than the second lens unit. The first lens unit is a negative lens unit. The lens units disposed closer to the reduction side than the second lens unit satisfy |dn/dt|<1.0×10−5. Magnification-side positive lens elements disposed closer to the magnification side than a negative lens element whose effective diameter is smallest in the lens units disposed closer to the reduction side than the second lens unit satisfy {9.0×Σ(1/fpA)+5.0×Σ(1/fpB)+0.5×Σ(1/fpC)}/Σ(1/fp)<1. Reduction-side positive lens elements disposed closer to the reduction side than the negative lens element whose effective diameter is smallest satisfy {9.0×Σ(1/fpA)+0.3×Σ(1/fpB)+2.0×Σ(1/fpC)}/Σ(1/fp)<1. Chromatic aberration is corrected and focus variations by temperature changes are reduced.

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