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Detection mark and method and apparatus for detecting mark

  • US 5,210,411 A
  • Filed: 06/27/1991
  • Issued: 05/11/1993
  • Est. Priority Date: 06/29/1990
  • Status: Expired due to Term
First Claim
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1. A detection mark comprising:

  • a source of excitation light;

    a pattern formed from a thin phosphor layer which emits light having a different wavelength from that of excitation light from said source and irradiated on a surface side of said phosphor layer,an undercoat layer which is formed on a rear surface side of said phosphor layer and reflects said excitation light;

    said undercoat layer having a selected reflectance characteristic so as to provide a ratio of an output voltage obtained from detected light emitted from said phosphor layer to that of excitation light reflected from said undercoat layer which is at least 1.6;

    means for pulsing said source of excitation light to generate pulses of light emitted from said phosphor layer; and

    means for detecting and counting said pulses of emitted light to determine a width dimension of said phosphor layer.

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