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Browse Prior Art Database

Hollow Reflecting Light Collector Tube

IP.com Disclosure Number: IPCOM000081889D
Original Publication Date: 1974-Aug-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 57K

Publishing Venue

IBM

Related People

Cronquist, DH: AUTHOR

Abstract

This hollow light collector tube accepts low-angle scattered light from a document traveling substantially parallel to the scanned line, which light is mostly lost due to surface reflection in a solid tube.

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Hollow Reflecting Light Collector Tube

This hollow light collector tube accepts low-angle scattered light from a document traveling substantially parallel to the scanned line, which light is mostly lost due to surface reflection in a solid tube.

A longitudinal cross-sectional view of an embodiment comprising a cylindrical tube 10 is shown in (a). A beam of light from a laser 12 is scanned along a line parallel to the longitudinal axis of the tube 10 on a document 14. Light rays 16 and 18 are reflected from the document as illuminated by the laser beam 20. The light ray 16 is reflected by the inner wall of the tube 10 and eventually strikes a photosensitive device 22 at one end of the tube 10. The other light ray 18 is reflected by the inner wall until it strikes the inner end surface 24 of the tube 10, from which it is then reflected to the photosensitive device 22 as for the first ray
16.

Cross-sectional views of four different embodiments of the tube 10 are given at (b), (c), (d) and (e). The latter tube 10e is extremely easy to construct and takes advantage of more reflected light entering the interior of the tube 10.

The basic tube 10 functions as follows: The light that enters the tube 10 as indicated at (a), (b), (c) and (d) is reflected from one part of the internal wall surface to another, and eventually some portion of this light reaches the photosensitive device 22. As the light is conducted through the tube 10, it experiences losses due to absorption in the walls and losses due to escape through the laser access slot and entrance window. The light that travels the furthest to reach the photosensitive device 22, is attenuated more than the light that travels a short distance. A curve of tube output intensity versus distance on a uniformly reflecting scanned line would show an exponential relationship. The light loss is directly related to the number of reflections experienced by the light. Tube efficiency is measured with respect to the low point on the output curve.

A conical tube embodiment is shown in cross section at (f). The conical tube 10f is a more efficient light collector tube than the cylinder tube 10 for the following reasons. A specular cone reflector will eventually reflect any ray of light out of the large end of the cone after a sufficient number of reflections have taken pl...