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Laser Raster Scanner with Separated Incident and Reflected Beams

IP.com Disclosure Number: IPCOM000076171D
Original Publication Date: 1972-Jan-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

McMurtry: AUTHOR [+2]

Abstract

A laser raster scanner is disclosed in the IBM Technical Disclosure Bulletin by M. Latta, Vol. 13, No. 12, May 1971 p 3879. This publication discusses a method for producing a laser raster scanner by essentially sharing the laser and rotating mirror of a laser printer. A laser beam passes through beam splitter BS2 and through lenses L2. It then hits a moving mirror which deflects the beam onto the document to be scanned. The reflected beam then returns to the moving mirror and passes back through lenses L2 to beam splitter BS2. It then passes into the photomultiplier tube (PMT) for detection.

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Laser Raster Scanner with Separated Incident and Reflected Beams

A laser raster scanner is disclosed in the IBM Technical Disclosure Bulletin by M. Latta, Vol. 13, No. 12, May 1971 p 3879. This publication discusses a method for producing a laser raster scanner by essentially sharing the laser and rotating mirror of a laser printer. A laser beam passes through beam splitter BS2 and through lenses L2. It then hits a moving mirror which deflects the beam onto the document to be scanned. The reflected beam then returns to the moving mirror and passes back through lenses L2 to beam splitter BS2. It then passes into the photomultiplier tube (PMT) for detection.

In the above system, the beamsplitter BS2 attenuates the light reaching the PMT by at least 75%. Further, since the incident and reflected beams both pass through lenses L2 and reflect off surfaces BS2, the rotating mirror and moving mirror, even slight backscatter from the optical surfaces will reduce contrast.

An improvement to the system above is described below.

Fig. 1 shows a general schematic essentially identical to that described in the above publication, with the following exceptions: (1) Beamsplitter BS2 is eliminated; (2) The rotating mirror RM doubles in thickness; (3) Additional lenses C6, C5, L3 are added; (4) Beam straightening mirror M3 is added; (5) The moving mirror MM is made wider.

Fig. 2 shows how these components are used. Incident beam passes from the rotating mirror RM through lenses C4...