Browse Prior Art Database

Dual Laser Scanner for Enhancing Readability of Specularly Reflecting Labels

IP.com Disclosure Number: IPCOM000046098D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Dickson, LD: AUTHOR [+2]

Abstract

To improve the readability of specularly-reflecting bar code labels without degrading the readability of other labels, it is suggested that a checkout scanner use two solid-state lasers modulated at different frequencies and two detectors, only one of which would be equipped with a polarizing filter.

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Dual Laser Scanner for Enhancing Readability of Specularly Reflecting Labels

To improve the readability of specularly-reflecting bar code labels without degrading the readability of other labels, it is suggested that a checkout scanner use two solid-state lasers modulated at different frequencies and two detectors, only one of which would be equipped with a polarizing filter.

Referring to the drawing, the beam deflecting element in the checkout scanner could be a transparent, rotating disk 10 with a plurality of holographic optical elements formed in sectors of the disk. The scanner would include a first solid state laser, 1, the output from which would be modulated electronically by controlling the current supply to the laser by a driver circuit 1. The beam generated by laser 1 would be expanded by a conventional beam expander BX1 and directed toward disk 10 by small mirror M1. The disk 10 would deflect and focus beam 1. When beam 1 is reflected from an object 12 being scanned, the returned light is condensed by lens 14 onto a detector (DET) 1 which would be tuned to the modulating frequency of laser 1. A polarizing filter 16 placed ahead of DET 1 would improve the readability of any specularly reflecting label on object 12.

A second solid-state laser 2 would be modulated at a different frequency by varying the current supplied by a driver circuit 2. The beam produced by laser 2 would also scan the object 12. The returning light would be focused by lens 14 on a...