Holographic laser scanning system and process and apparatus and methods for designing and constructing the same

摘要

A holographic laser scanning system comprising a support disc rotatable about an axis of rotation, and having an inner perimeter, an outer perimeter, and an available light collecting region defined between the inner perimeter and the outer perimeter. A laser light source produce a laser beam having first and second components characterized by first and second polarization states, respectively. A plurality of holographic optical elements are supported on the support disc between the inner and outer perimeters, for scanning the laser beam and producing a laser scanning pattern for scanning a code symbol. Each holographic optical element has a beam steering portion disposed adjacent the outer perimeter for scanning the laser beam, and a light collecting portion disposed between the inner and outer perimeters for collecting laser light reflected off a code symbol scanned by the laser beam. The beam steering portion of each holographic optical element has a light diffraction efficiency that is optimized for the first polarization state of the laser beam incident thereon, and the light collecting portion of each holographic optical element has a light diffraction efficiency optimized for the second polarization state of laser light reflected off the scanned code symbol. A photodetector is provided for detecting laser light reflected off the scanned code symbol. A polarization-selective filter is disposed before photodetector for transmitting collected laser light having second polarization state and blocking collected laser light having the first polarization state, thereby reducing the effects of glare produced when the laser beam scans bar code symbols on glossy substrates.