Holographic laser scanning system for carrying out laser beam scanning operations with improved scan angle multiplication efficiency and carrying out light collection operations with improved light collection efficiency

摘要

A holographic laser scanning system comprising: a housing of compact construction; a plurality of laser beam sources; a holographic scanning disc supporting a plurality of holographic optical elements having fringe structure of variable spatial frequency; a plurality of laser beam folding mirrors disposed about the holographic scanning disc; a plurality of light focusing surfaces disposed below the holographic scanning disc; and a plurality of photodetectors disposed at the focal points of the light focusing surfaces. During laser beam scanning operations, each laser beam is transmitted through the outer edge portion of each holographic optical element at an angle of incidence substantially greater than twenty-three degrees relative to a normal vector drawn thereto, preferably forty-three degrees. During light collection operations, a portion of the laser light rays reflected off a code symbol scanned by a produced laser scanning plane is collected over the total surface area of the holographic optical element producing the laser scanning plane. The collected laser light rays are focused by the light focusing surface to the respective photodetector, for detecting the intensity of the focused laser light rays for detection and generation of a scan data signal for subsequent processing. By virtue of the system of the present invention, laser beam scanning operations are carried out with improved scan angle multiplication efficiency and light collection operations are carried out with improved light collection efficiency.