Holographic laser scanning system and process and apparatus and method

• US 6,073,846 A
• Filed: 10/07/1996
• Issued: 06/13/2000
• 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:
  US08/726,522
• Time in Patent Office: 1,345 Days
• Field of Search: 235/462.01, 235/462.02, 235/462.24-462.26, 235/472.01, 235/472.02, 235/375
• US Class Current: 235/462.01
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• 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 employing laser beam production module with optical components geometrically constrained so as to be capable of producing a laser scanning beam having a controlled beam aspect-ratio substantially reduced astigmatism and minimal dispersion during laser beam scanning operations.

Claims

1. A holographic laser scanning system for scanning code symbols, comprising:

a system housing defining an interior space and having a light transmission aperture permitting light to exit and enter said interior space during laser scanning operations carried out by said holographic laser scanning system;

a laser diode disposed within said system housing, for producing a laser beam having a plurality of spectral components, an elliptical beam cross-section with a prespecified aspect ratio, and astigmatic beam characteristics inherently-introduced by virtue of the construction of said laser diode;

a holographic scanning disc mounted within said system housing and rotatable about an axis of rotation during laser beam scanning operations and having one or more holographic optical elements disposed substantially within a common plane extending through said holographic scanning disc, for scanning said laser beam while said laser beam is directed through a selected portion of said holographic scanning disc rotating about said axis of rotation and thereby producing a laser scanning pattern which is projected through said light transmission aperture for scanning code symbols presented to said laser scanning pattern; and

a laser beam production module mounted within said system housing and being integrated with said laser diode, said laser beam production module further including

(i) module housing of compact construction for supporting a configuration of optical and electro-optical components in a fixed spatial relationship during laser beam scanning operations,

(ii) a light diffractive grating of multi-function character mounted within said module housing, and having a substantially planar geometry, a grating structure of fixed spatial frequency, and an incident surface through which said laser beam enters said light diffractive grating, said light diffraction grating further being supported at a predetermined angle with respect to said common plane as said laser beam exiting said light diffractive grating is directed through a selected portion of said holographic scanning disc as said holographic scanning disc rotates about said axis of rotatation, and

(iii) a light converging element having an optical axis and being mounted within said module housing and proximately disposed at a predetermined distance (d) from said laser diode, so as to converge said laser beam by a predetermined amount as said laser beam is transmitted from said laser diode, along said optical axis and through said light converging element, towards said light diffractive grating;

wherein said optical axis of said light converging element is configured at an angle of incidence relative to the incident surface of said light diffractive grating so that said prespecified aspect ratio of said laser beam is modified in a predetermined manner as said laser beam is transmitted through both said light converging element and said light diffractive grating, towards said holographic scanning disc;

wherein said predetermined distance (d) between said light converging element and said laser diode is configured so that said astigmatic beam characteristics of said laser beam are substantially reduced after said laser beam is transmitted through both said light converging element and said light diffractive grating and travels beyond said light diffractive grating towards the holographic optical elements on said holographic scanning disc; and

wherein said light diffractive grating in said laser beam production module and each said holographic optical element on said holographic scanning disc cooperate during laser beam scanning operations so that said laser beam is transmitted through said light diffractive grating and each said holographic optical element on said holographic scanning disc with a minimal occurrence of dispersion of said plurality of spectral components during laser beam scanning operations.

2. The holographic laser scanning system of claim 1, wherein said light diffractive grating is a holographic optical element, and said grating structure of fixed spatial frequency comprises a fringe structure of fixed spatial frequency.

3. The holographic laser scanning system of claim 1, wherein said light converging element comprises a light refractive element.

4. The holographic laser scanning system of claim 3, wherein said light refractive element comprises an aspheric collimating lens.

5. The holographic laser scanning system of claim 1, wherein said laser beam exiting from said light diffractive grating is modified so that said aspect ratio is substantially 1, for the case of beam circularization.

6. The holographic laser scanning system of claim 1, wherein said astigmatic beam characteristics are minimized.

7. The holographic laser scanning system of claim 1, wherein said astigmatic beam characteristics are substantially eliminated.

8. The holographic laser scanning system of claim 1, wherein said laser diode is a visible laser diode for producing a visible laser beam.

9. The holographic laser scanning system of claim 1, wherein said predetermined angle is automatically configured upon mounting said laser beam production module within a preconfigured mounting fixture disposed within said system housing.

10. The holographic laser scanning system of claim 1,

wherein said

laser beam production module further comprises a mirror mounted within said module housing, and disposed between said light converging element and said light diffractive grating, for folding the path of said laser beam exiting

said light converging element and directing said laser beam through said light diffractive grating.

11. The holographic laser scanning system of claim 1, which further comprises a plurality of said laser beam production modules arranged about said holographic scanning disc.

12. The holographic laser scanning system of claim 10, which further comprises a plurality of photodetectors for detecting laser light reflected of an object during laser beam scanning operations.