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DRIVER FOR SPECKLE REDUCTION DIFFUSING SCREENS

IP.com Disclosure Number: IPCOM000024266D
Original Publication Date: 1980-Feb-29
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 71K

Publishing Venue

Xerox Disclosure Journal

Abstract

To reduce the small scale scintillation or "speckle" of an optically projected image, the projection system includes a pair of closely spaced, counterrotating diffusion screens 11 and 12 for producing controlled diffusion of the projected image. The counterrotation of the screens 11 and 12 not only reduces by a factor of two the angular velocity at which the screens 11 and 12 must be driven to achieve a given amount of diffusion but also tends to cause counterbalancing of any mechanical imbalance the individual rotating screens 11 and 12 may exhibit.

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XEROX DISCLOSURE JOURNAL

DRIVER FOR SPECKLE REDUCTION DIFFUSING SCREENS
Antonio Naf f ara te

Proposed Classification
U.S. Cl. 353/122 Int. Cl. G03b 21/00

To reduce the small scale scintillation or "speckle" of an optically projected image, the projection system includes a pair of closely spaced, counterrotating diffusion screens 11 and 12 for producing controlled diffusion of the projected image. The counterrotation of the screens 11 and 12 not only reduces by a factor of two the angular velocity at which the screens 11 and 12 must be driven to achieve a given amount of diffusion but also tends to cause counterbalancing of any mechanical imbalance the individual rotating screens 11 and 12 may exhibit.

As shown, the diffusion screens 11 and 12 are included in a rear projection system for reducing the speckle of an image projected onto a viewing screen 13. In operation, an image bearing subject 14 is illuminated by light supplied by a suitable source 15 via a light concentrating lens 16, a tilted mirror 17 and a projection lens
18. The projection lens 18 focuses the illuminated subject 14 on an aperture A formed between the mirror 17 and an optical stop 19 and images the subject 13 onto the diffusion screens 11 and 12 via a collimating lens 21. The screens 11 and 12 are rotated by suitable drivers, such as individual motors 22 and 23, respectively, to produce controlled diffusion of the image. Another projection lens 24 focuses the diffused image on an enlarged ape...