Optical: systems and elements – Projection screen – Unitary sheet comprising plural refracting areas
Reexamination Certificate
2007-03-12
2008-09-09
Lee, Diane I. (Department: 2851)
Optical: systems and elements
Projection screen
Unitary sheet comprising plural refracting areas
C359S029000, C359S559000, C359S460000, C349S030000
Reexamination Certificate
active
07423808
ABSTRACT:
A Fresnel lens of the prior art is split into two Fresnel lenses to allow easier control of the horizontal and vertical viewing angles. In a second embodiment, the Fresnel lens is entirely eliminated. Instead, the diffuser contains elliptical microstructures so that the diffusing cones in orthogonal directions are different, eliminating the need for a Fresnel lens to perform this function. To compensate for the absence of the light collimation provided by the Fresnel lens, a diffuser with spatially varying diffusing angles is used.
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Haruna, Masamitsu et al.; “Laser beam lithographed micro-Fresnel lenses”; 1990,Applied Optics, vol. 29, No. 34, pp. 5121-5126.
Cruz Magda
K Laser Technology Inc.
Lee Diane I.
Townsend and Townsend / and Crew LLP
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