Offset projection lens for use with reflective spatial light modulators
First Claim
1. A reverse telephoto offset projection lens, said projection lens having an objective end and an opposite modulator end, said reverse telephoto offset projection lens comprising:
- a telecentric lens group at said modulator end of said projection lens for receiving light from said modulator end, said telecentric lens group being telecentric in modulator space; and
a objective lens group at said objective end of said projection lens; and
wherein said objective lens group and said telecentric lens group are selected to to provide an air equivalent back focal distance of at least 3.3 inches.
1 Assignment
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Accused Products
Abstract
An offset reverse telephoto projection lens that is telecentric in modulator space and has an air equivalent back focal distance of at least 3.3 inches and preferably at least 4.0 inches. The lens comprising, from the image side, a first objective lens group 408 having a negative power and a second telecentric lens group having a positive power. The second telecentric lens group 410 is telecentric in object space such that the image of the aperture is focused at infinity and light converges on the object plane perpendicular to the axis of the lens. Embodiments of the lens have a back focal distance to effective focal length ratio of at least 0.86:1, preferably at least 1.2:1, more preferably at least 1.3:1, still more preferably at least 4.08:1, and most preferably 5.0:1. The embodiments described have a field of view between 14 degrees and 73 degrees, have throw ratios of 1.2:1 to 7:1, and an overall length ranging from less than 5 inches to 12.5 inches.
278 Citations
30 Claims
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1. A reverse telephoto offset projection lens, said projection lens having an objective end and an opposite modulator end, said reverse telephoto offset projection lens comprising:
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a telecentric lens group at said modulator end of said projection lens for receiving light from said modulator end, said telecentric lens group being telecentric in modulator space; and a objective lens group at said objective end of said projection lens; and wherein said objective lens group and said telecentric lens group are selected to to provide an air equivalent back focal distance of at least 3.3 inches. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. An image display system for projecting an image, said image display system comprising:
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a light source for generating a beam of light; a controller for generating electrical control signals; a spatial light modulator for receiving said electrical control signals and for selectively modulating said beam of light in response to said electrical control signals; a prism assembly for transmitting said selectively modulated beam of light; and a reverse telephoto projection lens for focusing said selectively modulated beam of light, said reverse telephoto projection lens telecentric in modulator space and providing an air equivalent back focal distance of at least 3.3 inches. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30)
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Specification