Browse Prior Art Database

Holographic Disc

IP.com Disclosure Number: IPCOM000043037D
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Dickson, LD: AUTHOR [+3]

Abstract

A known type of optical scanner uses a retro-reflective, rotating, multi-faceted holographic disc to deflect an impinging laser beam. At least two factors have to be considered in designing such a disc. The facet sizes should be such that there is a limited variation in light collection efficiency from one facet to the next. The facet sizes should also minimize scan dead time, that is, the time during which a scan line is beyond the edges of the exit window. This article suggests that the annular dimensions as well as the angular widths of facets be adjusted to minimize scan dead time while limiting variations in light collection efficiency. Fig.

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Holographic Disc

A known type of optical scanner uses a retro-reflective, rotating, multi-faceted holographic disc to deflect an impinging laser beam. At least two factors have to be considered in designing such a disc. The facet sizes should be such that there is a limited variation in light collection efficiency from one facet to the next. The facet sizes should also minimize scan dead time, that is, the time during which a scan line is beyond the edges of the exit window. This article suggests that the annular dimensions as well as the angular widths of facets be adjusted to minimize scan dead time while limiting variations in light collection efficiency. Fig. 1 shows part of a known type of holographic disc in which different facets 10, 12 and 14 have different widths to provide uniform light collection efficiency in a retro-reflective mode. The uniform light collection efficiency can create scanner dead time where the ends of the scan lines are beyond the exit window from the scanner. Fig. 2 shows a modified holographic disc in which the angular widths of facets 16, 18, 20, and 22 are more nearly uniform to reduce scanner dead time. To make the light collection efficiency more uniform, facets 16 and 20 have reduced annular dimensions relative to facets 18 and 22. Fig. 3 discloses still another form of the modified holographic disc in which facets 24 and 26 are each surrounded on three sides by facets 28 and 30. This arrangement also minimizes scanner dead ti...