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Light-integrating rangefinding device and method

  • US 7,554,652 B1
  • Filed: 02/29/2008
  • Issued: 06/30/2009
  • Est. Priority Date: 02/29/2008
  • Status: Active Grant
First Claim
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1. A method for optically measuring a range R of an object from a rangefinding device, comprising the steps of:

  • a) emitting a train of light pulses from said rangefinding device toward said object for reflection thereby, each of said light pulses having an emission time and having a pulse duration corresponding to a round-trip time to a maximum range;

    b) detecting light received by said rangefinding device during three time intervals of a same gate duration, said gate duration corresponding to twice the pulse duration, said time intervals being determined by;

    a background gate closing at the emission time of one of said light pulses;

    a ranging gate centered on the emission time of another one of said light pulses; and

    a pulse energy gate opening at the emission time of yet another one of said light pulses;

    c) integrating light detected during each of said time intervals, thereby obtaining an integrated light value for each of said gates;

    d) normalizing the integrated light value for said ranging gate using the integrated light values for the background and pulse energy gates, thereby obtaining a normalized ranging measurement; and

    e) determining said range R of the object from said normalized ranging measurement and calibration data.

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