Browse Prior Art Database

Scanner with Tandem Stationary Holographic Discs

IP.com Disclosure Number: IPCOM000051437D
Original Publication Date: 1981-Jan-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 53K

Publishing Venue

IBM

Related People

Dickson, LD: AUTHOR [+2]

Abstract

The drawings depict a scanner capable of generating relatively complex scan patterns without complex arrangements of beam-folding mirrors. Individual scan lines in the pattern are formed by directing one or more laser beams through a tandem arrangement of stationary, semi-circular, hologram-bearing discs.

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Scanner with Tandem Stationary Holographic Discs

The drawings depict a scanner capable of generating relatively complex scan patterns without complex arrangements of beam-folding mirrors. Individual scan lines in the pattern are formed by directing one or more laser beams through a tandem arrangement of stationary, semi-circular, hologram-bearing discs.

Referring to Fig. 1, the scanner is used to scan identifying labels on products being moved along a surface 10 having a transparent scanner window 12. A light beam is generated by a laser 14. The beam is split into two components 16 and 18 by a conventional beam splitter 20. The first component 16 is directed through a beam expanding/focussing lens 22 to a small mirror 24. The beam reflected from mirror 24 is redirected by a larger mirror 26 toward the bottom surface of a double-sided mirror 28. The second beam component 18 is directed by a mirror 30 to another beam/expanding focussing lens 32. The beam which emerges from the element 32 is folded by small mirror 34 and larger mirror 36 to impinge on the top surface of the double-sided mirror 28.

The double-sided mirror 28 is mounted in a transparent glass tube 38 which is rotated about an axis which is generally aligned with the impinging beams. A suitable drive motor 40 and gearing arrangement 42 may be employed to rotate the glass tube 38 at a relatively high speed. The combination of the double-sided mirror 28 and the glass tube 38 is referred to hereafter as a wobbulating mirror.

A semi-circular mirror 44, having a frustoconical configuration, is positioned adjacent the wobbulating mirror. As the wobbulating mirror rotates, the reflected light beam sweeps a circular path centered on the point of incidence of the beam with the wobbulating mirror surface. The sweeping, circular beam is deflected by the frustoconical mirror 24 toward a first semi-circular holographic disc 46, the details of which will be provided later. The holographic disc 46 deflects the beam toward a second semi-circular holographic disc 48. The holographic disc 48 redirects the beam toward the transparent scanner window 12.

The system is preferably a retro-reflective one. That is, light reflected from an object passing over window 12 returns through discs 48 and 46, frostoconical mirror 44 and the wobbulating mirror to one of the mirrors 26 or 36 depending on whether the top or bottom surface of the wobbulating...