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Portable laser diode scanning head having a focusing lens and an aperture

  • US 5,247,162 A
  • Filed: 04/24/1991
  • Issued: 09/21/1993
  • Est. Priority Date: 02/28/1985
  • Status: Expired due to Term
First Claim
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1. A laser scanning head for reading bar-coded symbols, comprising:

  • (a) an actuatable laser diode mounted in the head for generating an incident laser beam of relatively low power, the laser diode having a p-n junction as the emitter of the laser beam;

    (b) optic means mounted in the head for forming and directing the incident laser beam along a first optical path toward a reference plane located exteriorly of the head and to a symbol located in a working range in the vicinity of the reference plane, the laser beam reflecting off the symbol and returning along a second optical path back towards the head;

    the optic means including a focusing lens and an aperture stop both located in the first optical path in the immediate vicinity of the laser light source for forming the incident laser beam to have a beam cross-section of an altered size and shape within the working range, the focusing lens being located between the aperture stop and the laser light source;

    the aperture stop defining a shaped opening which in cross-section is smaller than the beam cross-section at the aperture stop to permit a portion of the incident light beam to pass through the aperture stop and to directly determine the beam'"'"'s size and shape within the working range, such cross-section being measured in the direction perpendicular to said p-n junction;

    (c) a scanner mounted in the head for scanning the laser beam across the symbol, the returning portion of the laser light having a variable intensity over the scan;

    (d) a sensor mounted in the head for detecting the variable intensity of the returning portion of the laser light, and for generating a sensor signal representative of the detected variable light intensity;

    (e) a signal processor mounted in the head for processing the sensor signal and for generating a processed signal indicative of characteristics of the symbol; and

    (f) an actuator mounted in the head for actuating the laser light source.

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