SPECKLE NOISE REDUCING FOR LASER BASED BARCODE READERS

摘要

A method and apparatus for reducing speckle noise in laser based barcode readers. The apparatus includes a semiconductor laser diode for producing a laser beam. The apparatus also includes electronic circuitry operative to alternate the current passing through the semiconductor laser diode between a current above the threshold current and a current below the threshold current. The current passing through the semiconductor laser diode is alternated with a sufficiently high transition rate for reducing the coherence length of the laser beam.