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Fingerprint imaging

  • US 5,625,448 A
  • Filed: 05/08/1995
  • Issued: 04/29/1997
  • Est. Priority Date: 03/16/1995
  • Status: Expired due to Term
First Claim
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1. A fingerprint reader comprising:

  • an imaging system for generating an optical beam defining an optical image of a fingerprint;

    a scanning galvanometer;

    a scanning mirror mounted on said galvanometer for angular movement through a plurality of positions;

    a linear array of sensors;

    an optical system for directing said optical image at said scanning mirror for reflection to said linear array of sensors, said optical system comprising;

    an F-Theta scan lens in which lateral displacement of the image from the optical axis is proportional to the angle of entry of light to the lens over a relatively large entry angle;

    a focus lens, said scan lens and said focus lens having a common focal point between them, said scanner mirror being interposed between said scan lens and said focus lens at said common focal point;

    a mirror controller for energizing said galvanometer to scan said mirror about a scan axis and scan said optical image across said linear array of sensors;

    a means for generating a scan position command signal in accordance with a position of said finger as said finger moves over said platen, wherein said mirror controller and said galvanometer are responsive to said scan position command signal to drive said scanning mirror to an angular position precisely proportional to said scan position command signal.

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