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Pattern scanning device

  • US 5,289,253 A
  • Filed: 11/12/1991
  • Issued: 02/22/1994
  • Est. Priority Date: 03/23/1989
  • Status: Expired due to Fees
First Claim
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1. A device for scanning the surface of a generally cylindrical object carrying a raised pattern thereon so as to detect that pattern, which device comprises:

  • a. a transparent optical body having a substantially arcuate configuration about a first axis and having a convergent radial cross-section, and a channel parallel to and substantially co-axial with that axis, which channel presents a surface substantially parallel to the said axis, upon which the object whose surface is to be observed can be placed, and the underside of which surface serves as the optical base face to the convergent radial cross-section to the optical body;

    b. a source of an incident light beam adapted to be directed onto a light entry face of the convergent cross-section of the optical body, the configuration of the optical body being such that the incident light beam is adapted to strike the under-side of the said optical base face at substantially the angle of total internal reflection for the material from which the optical body is fabricated and to be reflected through a light exit face of the convergent cross-section of the optical body;

    c. means for causing the said incident light beam progressively to traverse the said optical base face of the optical body; and

    d. a means for observing the light reflected from the underside of the said optical base face through a light exit face of the convergent cross-section of the optical body and for providing a signal dependent upon the intensity of the light detected.

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