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

• US 6,006,993 A
• Filed: 10/17/1997
• Issued: 12/28/1999
• Est. Priority Date: 08/17/1994
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Dickson, LeRoy, Amundsen, Thomas, Knowles, Carl Harry, Groot, John
• Primary Examiner(s): LE, THIEN MINH
• Application Number:
  US08/953,593
• Time in Patent Office: 802 Days
• Field of Search: 235/462.25, 235/462.24, 235/462.01, 235/462.08, 235/462.09, 235/462.41, 235/462.42, 235/462.34, 359/17, 359/18, 359/19, 359/30, 359/12
• US Class Current: 235/462.25
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 26/106 having diffraction gratings as scanning elements, e.g. holographic scanners holographic optical elements G02B5/32, holography G03H
• CPC Class Codes: G06K 17/0022 arrangements or provisions for transferring data to distant stations, e.g. from a sensing device "transfer between computer elements G06F13/00 "; data-transmission H04L
• CPC Class Codes: G06K 2207/1012 Special detection of object
• CPC Class Codes: G06K 2207/1013 Multi-focal
• CPC Class Codes: G06K 2207/1016 Motor control or optical moving unit control
• CPC Class Codes: G06K 2207/1017 Programmable
• CPC Class Codes: G06K 2207/1018 Source control
• CPC Class Codes: G06K 7/10 by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
• CPC Class Codes: G06K 7/10564 Light sources
• CPC Class Codes: G06K 7/10584 Source control
• CPC Class Codes: G06K 7/10594 Beam path
• CPC Class Codes: G06K 7/10603 Basic scanning using moving elements
• CPC Class Codes: G06K 7/10663 using hologram
• CPC Class Codes: G06K 7/10673 Parallel lines
• CPC Class Codes: G06K 7/10693 for omnidirectional scanning
• CPC Class Codes: G06K 7/10702 Particularities of propagating elements, e.g. lenses, mirrors G06K7/10831 takes precedence
• CPC Class Codes: G06K 7/10792 Special measures in relation to the object to be scanned
• CPC Class Codes: G06K 7/10801 Multidistance reading
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/10851 : Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03
• CPC Class Codes: G06K 7/10861 : sensing of data fields affixed to objects or articles, e.g. coded labels postal sorting B07C3/14, conveying articles B65G47/48
• CPC Class Codes: G06K 7/10871 : randomly oriented data-fields, code-marks therefore, e.g. concentric circles-code
• CPC Class Codes: G06K 7/10881 : constructional details of hand-held scanners
• CPC Class Codes: G06K 7/10891 : the scanner to be worn on a finger or on a wrist
• CPC Class Codes: G06K 7/109 : adaptations to make the hand-held scanner useable as a fixed scanner
• CPC Class Codes: G06K 7/14 : using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G07F 9/002 : Vending machines being part of a centrally controlled network of vending machines
• CPC Class Codes: G07G 1/0045 : with a code reader for reading of an identifying code of the article to be registered, e.g. barcode reader or radio-frequency identity [RFID] reader
• CPC Class Codes: G07G 1/0054 : with control of supplementary check-parameters, e.g. weight or number of articles

Abstract

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.

Claims

1. A holographic laser scanning system for carrying out laser beam scanning operations with improved scan angle multiplication efficiency and laser light collection operations with improved light collection efficiency, said holographic laser scanning system comprising:

a housing of compact construction;

a holographic scanning disc disposed within said housing for rotation about an axis;

a plurality of laser beam sources disposed within said housing, for producing plurality of laser beams and directing each said laser beam towards said holographic scanning disc at an angle of incidence substantially greater than twenty-three degrees relative to a normal vector drawn to said holographic scanning disc;

said holographic scanning disc including a plurality of holographic optical elements, each said holographic optical element having

an outer edge portion for focusing and deflecting said laser beams as said laser beams are transmitted through said outer edge portion at said angle of incidence during said laser beam scanning operations, and

a total surface area for collecting light rays reflected off a scanned code symbol for subsequent focusing and detection during light collection operations;

a plurality of laser beam folding mirrors disposed within housing and about said holographic scanning disc, for folding said deflected laser beams and producing a plurality of laser scanning planes outside of said housing, said plurality of laser scanning planes intersecting to produce a laser scanning pattern within a 3-D scanning volume for scanning a code symbol present therein;

wherein, during laser beam scanning operations, each said laser beam produced from said laser beam sources is transmitted through said outer edge portion of each said holographic optical element as said holographic scanning disc rotates about said axis of rotation, and

wherein, during light collection operations, a portion of the laser light rays reflected off a code symbol scanned by one said laser scanning plane is collected over said total surface area of said holographic optical element producing said laser scanning plane;

a plurality of light focusing surfaces disposed within said housing and beneath said holographic scanning disc, each said light focusing surface focusing towards a focal point the laser light rays collected by one said holographic optical element positioned above said light focusing surface during said light collecting operations; and

a plurality of photodetectors, each said photodetector being disposed within said housing and at the focal point of one said light refocusing surface, for detecting the intensity of said focused laser light rays for detection and generation of a scan data signal for subsequent processing,

whereby said laser beam scanning operations are carried out with improved scan angle multiplication efficiency and said light collection operations are carried out with improved light collection efficiency.

2. The holographic laser scanning system of claim 1, wherein said angle of incidence of each said laser beam is about forty-three degrees.

3. The holographic laser scanning system of claim 1, wherein each said light focusing surface is a parabolic light reflective surface having an optical axis and each said photodetector is disposed at said focal point above said holographic scanning disc, and radially aligned with the optical axis of said parabolic light reflective surface.

4. The holographic laser scanning system of claim 3, wherein said parabolic light reflective surface is realized as a parabolic mirror element having parabolic surface patch characteristics.

5. The holographic laser scanning system of claim 1, wherein each said laser beam source comprises a visible laser diode.

6. The holographic laser scanning system of claim 1, wherein each said laser beam folding mirror is a planes mirror.