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Method for controlling a light source in a night vision surveillance system

  • US 6,603,507 B1
  • Filed: 06/09/1999
  • Issued: 08/05/2003
  • Est. Priority Date: 04/12/1999
  • Status: Expired due to Term
First Claim
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1. A method for controlling a light source in a night vision system, which comprises a pulsed light illuminator and a gated light sensor, the method comprising:

  • estimating or measuring a desired observing distance d of an object;

    setting a shortest distance d1 for back-scattering lights to enter the light sensor;

    determining a pulse width Tp of a light beam emitted from the pulsed light illuminator, in which Tp=2(d−

    d1)/c, where c represents a light speed;

    determining a duty cycle D for the pulsed light illuminator, wherein D is equal to Tp/(Tp+T2d), where T2d=2d/c;

    the pulsed active-light illuminator emitting light pulses with the pulse width Tp and an emitting period (Tp+T2d); and

    the light sensor receiving the light pulses which are reflected by the object, wherein the light sensor has a sensing period identical to the emitting period but with a delay time of T2d.

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