Beam shaping for optical scanners

摘要

An optical scanner such as a bar code scanner includes a laser diode to create the scanning laser beam. Laser diodes are characteristically astigmatic, and when passed through a rotationally symmetric lens the beam typically forms a waist both in the x (scanning) direction and in the y (perpendicular) direction. The width of the beam envelope in the x direction is adjusted by means of a conventional lens. The width of the beam envelope in the y direction is adjusted by the use of a non-planar mirror, preferably a cylindrical mirror, as the rotating or oscillating element.