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Laser Scanner And Clock Scheme

IP.com Disclosure Number: IPCOM000041145D
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Baxter, DW: AUTHOR [+3]

Abstract

The scanner and clock structure as illustrated in the Figs. provides a clock grid optically coincident with the subject being scanned, for best accuracy. It uses nearly all the same optical elements as the data path, thereby keeping the complexity of the clock grid function to a minimum.

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Laser Scanner And Clock Scheme

The scanner and clock structure as illustrated in the Figs. provides a clock grid optically coincident with the subject being scanned, for best accuracy. It uses nearly all the same optical elements as the data path, thereby keeping the complexity of the clock grid function to a minimum.

As shown in Figs. 1 and 2, a light source such as a laser is used to provide the equivalent of a point source of illumination at point A, with divergence of angle B. This beam of light is directed by mirror C through lens D onto rotating polygon E, which causes the beam, after passing back through lens D to form scan line F on the subject of interest G.

Light reflected by the subject G retraces the path just described until it reaches beamsplitter H, which directs some of the reflected light to data detector
J. Beamsplitter H may be a polarizing beamsplitter which would cause only the component of light with polarization rotated away from that of the illuminating beam to reach the data detector.

Inserting prism assembly M (Fig. 3) into the path of the beam near scan line F provides an optically coincident but spatially separated clock signal as follows: Amplitude beamsplitting surface M1 reflects a small fraction of the incident beam to prism surface M2, on which is imprinted a grid of alternating reflective and absorptive lines. Light is reflected periodically from the lines to mirrored surface M3 and from there back through lens D, etc. Because th...