Abstract: A holographic laser scanning system for scanning bar code symbols. The system comprises a holographic scanning disc having a plurality of holographic optical elements disposed thereon for scanning the plurality of laser beams directed at the same incident angle. Each holographic optical element as substantially the same Bragg angle. The parabolic light reflective surfaces are disposed beneath the holographic scanning disc. Each parabolic light reflective surface has an optical axis disposed off the Bragg angle of the holographic optical elements, for focusing towards a focal point above the holographic scanning disc, the reflected light rays collected by each holographic optical element. A photodetector is disposed at the focal point of the corresponding parabolic light reflective surface above the holographic scanning disc, and is radially aligned with the optical axis of one parabolic light reflective surface.

Abstract: A holographic laser scanner for producing a high-resolution raster-type 2-D laser scanning pattern within a 3-D scanning volume. The scanner comprises a housing, holographic laser scanning mechanism disposed within the housing for producing a high-resolution raster-type 2-D scanning pattern within a 3-D scanning volume. The holographic laser scanning mechanism includes a laser beam source for producing a laser beam, and a holographic scanning disc rotatable about an axis of rotation and supporting a plurality of holographic optical elements. The laser beam is directed towards the holographic laser scanning disc at an angle of incidence so that the laser beam is diffracted by the holographic optical elements and produce a raster-type 2-D laser scanning pattern for scanning code symbols within the 3-D scanning volume.

Abstract: A code symbol reading system comprising first and second scanners. The first scanner employs a holographic scanning disc to generate an omnidirectional laser scanning pattern within a large 3-D scanning volume. The first scanner detects the location of a code symbol within the 3-D scanning volume and produces data indicative of its location therewithin. Using this location data, the second scanner produces a high density scanning pattern to aggressively scan the region in which the code symbol has been detected, and collect scan data for decode processing. By virtue of the system and method of the present invention, it is now possible to read bar code symbols located anywhere within very large volume of space, with a high degree of accuracy hitherto impossible using prior art techniques.

Abstract: A laser bar code symbol scanner embodying a narrow band-pass optical filtering system of novel construction. A first optical filter element is installed over the light transmission aperture of the scanner housing, and has wavelength selective properties which transmit only light having wavelengths from slightly below a predetermined wavelength in the visible band of the electromagnetic spectrum (e.g., greater than slightly below 670 nanometers). A second optical filter element is installed within the housing, along the focused laser return light path between the light focusing element and the light detecting element, and transmits only light having wavelengths from slightly above the predetermined wavelength (e.g., less than slightly above 670 nanometers). Collectively, the first and second optical filter elements cooperate to form a narrow wavelength band-pass filtering system centered about the predetermined wavelength, providing improved signal-to-noise ratio.

Abstract: A laser bar code symbol scanner embodying a narrow band-pass optical filtering system of novel construction. A first optical filter element is installed over the light transmission aperture of the scanner housing, and has wavelength selective properties which transmit only light having wavelengths from slightly below a predetermined wavelength in the visible band of the electromagnetic spectrum (e.g., greater than slightly below 670 nanometers). A second optical filter element is installed within the housing, along the focused laser return light path between the light focusing element and the light detecting element, and transmits only light having wavelengths from slightly above the predetermined wavelength (e.g., less than slightly above 670 nanometers). Collectively, the first and second optical filter elements cooperate to form a narrow wavelength band-pass filtering system centered about the predetermined wavelength, providing improved signal-to-noise ratio.