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Detection of three-dimensional information using a projected point or line of light

  • US 4,494,874 A
  • Filed: 07/07/1981
  • Issued: 01/22/1985
  • Est. Priority Date: 07/07/1981
  • Status: Expired due to Fees
First Claim
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1. A method of detecting three-dimensional information, comprising the steps of:

  • projecting a variable-intensity flying spot of light onto an object to be scanned;

    effecting a first scan by causing relative movement between object and light spot;

    receiving light-intensity signals in a single reflected light ray from the object point-by-scanned-point and modifying the intensity of the light spot in accordance with each received signal;

    effecting a second scan by causing relative movement between object and light spot; and

    reducing the light-spot intensity during the second scan at such points of the object where the signal was strong during the first scan, and increasing the light-spot intensity during the second scan at such points where the signal was weak during the first scan, said steps of effecting a first scan and a second scan comprising measurements of a multiplicity of points independent of light intensity at the object, so that accuracy of said measurements is not influenced by the light intensity at the object, the light-spot intensity during said second scan being dependent on said light-intensity signals of said first scan for preventing inaccuracy due to measurement delay and lag in modifying by a distance equal to scan velocity multiplied by measurement delay time.

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