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Parabolic Collimating Light Source

IP.com Disclosure Number: IPCOM000077761D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Polsgrove, JS: AUTHOR

Abstract

A parabolic collimating light source provides a rectangular collimated light beam which is brighter at its extremities than at the center of the beam, the beam being utilized to progressively scan a document.

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Parabolic Collimating Light Source

A parabolic collimating light source provides a rectangular collimated light beam which is brighter at its extremities than at the center of the beam, the beam being utilized to progressively scan a document.

Stationary light sources 11 and 13 are located, respectively, at the foci of stationary paraboloid reflectors 15 and 17. Light rays emanating from the light sources and striking the paraboloid reflectors are reflected therefrom in parallel light rays. The parallel light rays strike either lower parabolic reflector 19 or upper parabolic reflector 21, and are reflected therefrom onto a document being scanned located at the foci of the parabolic reflectors. The parabolic reflectors 19 and 21 are mounted on carriage 23 for movement in the scanning direction of arrow 25. Light reflected from the document is directed downward between parabolic reflectors 19 and 21, through a lens system onto a photoreceptive surface. Since light sources 11 and 13 are closer to the edge portions 15a and 17a of the paraboloid reflectors than the center portions 15b and 17b, light rays "a" are brighter than light rays "b", thereby compensating the scanning beam for the cosine /4/Theta light distribution error of the lens system.

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