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Browse Prior Art Database

Beam Position Adjusting Apparatus

IP.com Disclosure Number: IPCOM000085410D
Original Publication Date: 1976-Apr-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Lambiotte, JC: AUTHOR

Abstract

The position of the laser beam used in the scanning system of United States Patent 3,898,627, Fig. 1, can be manually adjusted by the use of a flat glass plate 10. Plate 10 is pivoted normal to the direction of beam 16, by knob 11, so as to refractively move the beam 16 in the plane of rotating polygonal mirror 12. If the beam 16 is mispositioned in this plane, i.e., the plane of scan, the scan field is not altered in quality or length, but it is shifted in the direction of scan, i.e., it is shifted axially along drum 13.

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Beam Position Adjusting Apparatus

The position of the laser beam used in the scanning system of United States Patent 3,898,627, Fig. 1, can be manually adjusted by the use of a flat glass plate 10. Plate 10 is pivoted normal to the direction of beam 16, by knob 11, so as to refractively move the beam 16 in the plane of rotating polygonal mirror 12. If the beam 16 is mispositioned in this plane, i.e., the plane of scan, the scan field is not altered in quality or length, but it is shifted in the direction of scan, i.e., it is shifted axially along drum 13.

Mispositioning of the beam 16 may occur, for example, from pointing or placing instability of laser source 14.

By placing flat glass plate 10 of optical material, for example, 1/16 inch thickness, immediately after modulator 15, the laser beam 16 can be repositioned in the scan plane without the requirement of a sensitive adjustment. Thus, this placement is advantageous for servicing personnel. The amount of beam movement achieved by a unit rotation of plate 10 is a function of the plate's thickness and its index of refraction.

Fig. 2 shows a single facet 17 of mirror 12. Dotted area 18 represents the midpoint of impact of the laser beam 12 on this facet.

This point can be moved in either direction, as shown by the arrows, by rotating plate 10.

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