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AN OPTICAL TECHNIQUE FOR ACHIEVING READ/WRITE SCANNING FROM A COMMON SCANNING ELEMENT

IP.com Disclosure Number: IPCOM000024363D
Original Publication Date: 1980-Jun-30
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 68K

Publishing Venue

Xerox Disclosure Journal

Abstract

A desirable approach for the design of an optical scanning device which must both read input information and provide an output to a writing process is to obtain precise optical synchronism between the two light beams, thereby avoiding the necessity to either phase-lock two independent scanning elements of a simultaneous system or to store read data in the case of a non-simultaneous scanning system.

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XEROX DISCLOSURE JOURNAL

AN OPTICAL TECHNIQUE FOR ACHIEVING READ/WRITE SCANNING FROM A COMMON SCANNING ELEMENT
Abbott Smith

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Proposed Classification
U.S. C1. 350/6.1 Int. C1. G02b 27/17

A desirable approach for the design of an optical scanning device which must both read input information and provide an output to a writing process is to obtain precise optical synchronism between the two light beams, thereby avoiding the necessity to either phase-lock two independent scanning elements of a simultaneous system or to store read data in the case of a non-simultaneous scanning system.

It is not possible to obtain optical synchronism in a system using rotating polygonal mirrors because the angular precision required of every mirror facet is beyond that which is achievable at reasonable cost. Neither is it practical to direct the read and write beams onto a single mirror facet at different angles because the required facet size is increased by the high obliquity of one beam, and separation of the beams after reflection may be very difficult.

In order to overcome these limitations, it is possible to use diffractive beam splitting to separate the two reflected beams. In a typical example, an incident beam containing several narrow spectral lines is reflected from a rotating prism to a diffraction grating, the rulings of which are parallel to the rotation axis of the prism. The zero order reflected beam becomes the reading beam, and the write beam can be chosen from an...