Patent EA-002627-B1 (EA)
Title: Holographic laser scanning system and process and apparatus and methods for designing and constructing the same
Inventor: DICKSON LEROY
IPC: G07G1/00
Filed: 1996-12-18
Abstract: 1. A holographic scanning device for use in a holographic laser scanner to produce a plurality of scanlines, 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 said inner perimeter and outer perimeter; a plurality of holographic facets, each being supported on said support disc between the inner and outer perimeters, and each having a facet surface area light collecting operations and at least a portion of said facet surface area being disposed adjacent said outer perimeter of said support disc for laser beam scanning operations, wherein the sum of all of the facet surface areas of said plurality of said holographic scanning facets is substantially equal to the surface area of said available light collecting region of said support disc. 2. The holographic scanning device of claim 1, wherein the refractive index of each said holographic facet has a variable spatial frequency over its facet surface-area, providing a focal length which is related to the distance of the scanline to be produced by said holographic scanning facet. 3. The holographic scanning device of claim 1, wherein the light collection efficiency of each said holographic facet is substantially equal. 4. A holographic scanning device of claim 1, wherein the inner surface boundary of at least one of said holographic facets has an inner radius which is substantially greater than the inner perimeter of said support disc. 5. The holographic scanning device of claim 1, wherein each said holographic facet is a volume transmission type hologram. 6. The holographic scanning device of claim 1, wherein each said holographic facet is a volume reflection type hologram. 7. The holographic scanning device of claim 1, wherein the average refractive index of each said holographic scanning facet is substantially equal over the entire facet surface area thereof. 8. The holographic scanning device of claim 1, wherein the outer portion of the facet surface area of each said facet used for scanning operations has a first average refractive index, whereas the remaining portion of the facet surface area of each said facet used for light collecting operations has a second average refractive index. 9. The holographic scanning device of claim 8, wherein said first average refractive index is different from said second average refractive index. 10. The holographic scanning device or claim 8, wherein the light diffraction efficiency of said outer portion of said facet surface area is optimized for a first polarization state of light, and the light diffraction efficiency of said remaining portion of said facet surface area is optimized for a second polarization state of light orthogonal to said first polarization state. 11. The holographic scanning device of claim 9, wherein said first polarization state is the S-polarization state and said second polarization state is the P-polarization state. 12. A holographic laser scanner for producing a 3-D laser scanning volume, which comprises: a housing having a scanning window; wherein said 3-D laser scanning volume is substantially greater than the volume of the housing of the holographic laser scanner, and provides full omni-directional scanning within said 3-D laser scanning volume. a light focusing mirror disposed beneath said laser scanning disc, for focusing towards a focal point above said laser scanning disc, the reflected light rays collected by each holographic scanning facet; and a photodetector disposed at said focal point above said laser scanning disc, for detecting the intensity of collected light rays focused by said light focusing mirror and transmitted through said scanning facet to said photodetector for detection and generating a scan data signal for subsequent processing; wherein the 1ight diffraction efficiency of each said scanning facet at the angle of incidence of said laser beam during said scanning is substantially greater than the light diffraction efficiency of the scanning of said focused laser beam are transmitted from said parabolic light focusing mirror towards said photodetector during light detection. 13. The holographic laser scanner of claim 12, in which said 3-D laser scanning volume has multiple focal planes and a highly confined geometry extending about a projection axis extending from said scanning window. 14. A holographic laser scanner which comprises: a scanner housing having an internal volume and a scanning window; and a 3-D laser scanning volume produced from said scanner housing, wherein the ratio of said 3-D scanning volume to the volume of said scanner housing is greater than about 5.0. a light focusing mirror disposed beneath said laser scanning disc, for focusing towards a focal point above said laser scanning disc, the reflected light rays collected by each holographic scanning facet; and a photodetector disposed at said focal point above said laser scanning disc, for detecting the intensity of collected light rays focused by said light focusing mirror and transmitted through said scanning facet to said photodetector for detection and generating a scan data signal for subsequent processing; wherein the 1ight diffraction efficiency of each said scanning facet at the angle of incidence of said laser beam during said scanning is substantially greater than the light diffraction efficiency of the scanning of said focused laser beam are transmitted from said parabolic light focusing mirror towards said photodetector during light detection. 15. A holographic laser scanner for producing a plurality of scanning planes each having a particular depth of focus and spatially confined within a 3-D scanning volume comprising: a plurality of symmetrically arranged laser diodes for simultaneously producing a plurality of laser beams; a plurality of holographic optical elements of the volume-transmission type for focusing and scanning said plurality of laser beams through said 3-D scanning volume, wherein each said holographic optical element is supported upon a rotating disc and produces one of said plurality of scanning planes when one said laser beam passes through the holographic optical element during the operation of the holographic laser scanner. 16. A holographic laser scanner which comprises: a scanning disc carrying a plurality of holographic optical elements while rotating about an axis of rotation; a photodetection unit disposed beneath said scanning disc; and a laser light source for producing a laser light beam which is directed through said scanning disc; whereupon, at each instant in time, said laser light beam is transmitted through one holographic optical element, is focused and scanned along a laser scanline for reflection off a code symbol, such that reflected laser light passes through the same holographic optical element and is thereafter collimaged for light intensity detection by said photodetection unit during operation of said holographic laser scanner. 17. A holographic laser scanner comprising: a plurality of lasers for simultaneously producing a plurality of laser beams; and a scanning disc supporting a plurality of holographic facets while rotating about an axis of rotation for focusing and scanning said plurality of laser beams so as to produce a complex scanning pattern within a 3-D scanning volume for omnidirectionally scanning code symbols presented within said 3-D scanning volume. 18. A holographic laser scanner for generating a complex scanning pattern having multiple scanning planes during a scanning pattern generation cycle, comprising: a scanner housing having an apertured scanning window; a plurality of lasers for simultaneously producing a plurality of laser beams; a rotating disc supporting a plurality of holographic facets for focusing and scanning said plurality of laser beams so as to produce a complex scanning pattern having multiple scanning planes; and wherein said apertured scanning window allows simultaneously projection of said multiple scanning planes, at angles which differ from each other over the duration of each scanning pattern generation cycle. 19. A holographic laser scanner for producing a complex laser scanning pattern consisting of a plurality of laser scanning planes each having a focal plane, said holographic laser scanner comprising: a support disc rotatable about an axis of rotation, and having an inner perimeter, outer perimeter, and an available light collecting region defined between said inner perimeter and outer perimeter; and a plurality of holographic facets, each being supported on said support disc between the inner and outer perimeters of said support disc, and each having a facet surface area for use in light collecting operations and at least a portion of said facet surface area being disposed adjacent said outer perimeter of said support disc for use in laser beam scanning operations, wherein said holographic optical elements are arranged on said support disc to maximize the use of the space on said support disc for light collection, while minimizing the laser beam velocity at the focal plane of each of said laser scanning plane. 20. A holographic laser scanner 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 said inner perimeter and outer perimeter; and a plurality of holographic facets, each being supported on said support disc between the inner and outer perimeters of said support disc, and each having a facet surface area for use in light collecting operations, wherein substantially all of the available light collecting surface area on said support disc is utilized and the light collection efficiency of each said holographic facet is substantially equal. 21. A holographic laser scanner comprising: a support disc rotatable about an axis of rotation, and having an inner perimeter