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Laser speckle velocity-measuring apparatus

  • US 4,912,519 A
  • Filed: 06/17/1988
  • Issued: 03/27/1990
  • Est. Priority Date: 06/19/1987
  • Status: Expired due to Fees
First Claim
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1. A laser speckle velocity-measuring apparatus comprising:

  • light projecting means for irradiating a light to a moving object;

    first and second photo sensing devices with light receiving points arranged at a predetermined distance so as to be away from each other in order to receive a scattered light from a surface of said object, said first photo sensing device outputting a preceding signal and said second photo sensing device outputting a delay signal;

    variable clock signal generating means for generating a variable frequency clock signal;

    first means for sampling said preceding signal at a rate determined by the clock signal to form first sampled data, and for shifting the first sampled data by predetermined stages, each stage corresponding to one period of the clock signal;

    second means for sampling said delay signal at a rate determined by the clock signal to form second sampled data, and for holding a plurality of said second sampled data;

    means for comparing the first sampled data output from said first means with each of the plurality of the second sampled data which are held by said second means, and for making data representing a correlation degree distribution relating said preceding signal and delay signal;

    clock signal control means for changing the frequency of the clock signal to control a delay time in said first means such that the first sampled data which was shifted by specified stages in said first means indicates a maximum value of said correlation degree distribution; and

    arithmetic operating means for calculating a length, a moving distance or a velocity of the object from the frequency of the clock signal and the distance between the light receiving points of said first and second photo sensing devices.

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