Browse Prior Art Database

Holographic Disk for Multiple Focal Plane Optical Scanner

IP.com Disclosure Number: IPCOM000039297D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Broockman, EC: AUTHOR [+3]

Abstract

This article describes a holographic disk for use in an optical scanner. The disk has multiple facets which produce a scan pattern having scan lines with different focal lengths. The facets are shaped to provide uniform light collection efficiency and scan lines of equal length for beams of different focal lengths. Referring to the drawing, the holographic disk includes a plurality of holographic optical elements or facets 10A, 10B, 10C, etc., mounted on a glass substrate. A laser beam impinges on the disk at a point 12. As the disk rotates relative to the point 12, the point of intersection is defined by a circular track 14. The length of the scan line generated by disk rotation for a particular facet is a function of the width of the facet measured along the track 14.

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Holographic Disk for Multiple Focal Plane Optical Scanner

This article describes a holographic disk for use in an optical scanner. The disk has multiple facets which produce a scan pattern having scan lines with different focal lengths. The facets are shaped to provide uniform light collection efficiency and scan lines of equal length for beams of different focal lengths. Referring to the drawing, the holographic disk includes a plurality of holographic optical elements or facets 10A, 10B, 10C, etc., mounted on a glass substrate. A laser beam impinges on the disk at a point 12. As the disk rotates relative to the point 12, the point of intersection is defined by a circular track 14. The length of the scan line generated by disk rotation for a particular facet is a function of the width of the facet measured along the track 14. The light collection efficiency of a facet is a function of its overall surface area. Scan lines having short focal lengths would be generated by a facet, such as 10A, having a relatively small overall area but a relatively wide angular dimension along the track 14. Scan lines having relatively long focal lengths would be generated by a facet, such as facet 10B, having a larger overall area to increase its light-collection ability, but a relatively small angular width along the track 14. The scanning angular width of each facet can be adjusted along track 14 to assure that the scan lines have equal lengths regardless of the focal length of...