Laser beam generation system employing a laser diode and high-frequency modulation circuitry mounted on a flexible circuit

• US 20080128510A1
• Filed: 10/30/2007
• Published: 06/05/2008
• Est. Priority Date: 11/24/2000
• Status: Active Grant

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Xian, Tao, Zhu, Xiaoxun, Veksland, Michael, Ren, Jie, Knowles, C. Harry, Liu, Yong, Good, Timothy, Giordano, Patrick, Schmidt, Mark, Kotlarsky, Anatoly, Tao, Xi, Liu, JiBin, Essinger, Steven, Gardner, John, Kearney, Sean, Ellis, Duane, Ciarlante, Nicholas, Hernandez, Mark, Zhuo, Ming, Furlong, John A.
• Granted Patent: US 7,806,336 B2
• Time in Patent Office: Days
• US Class Current: 235/462.42
• CPC Class Codes: A47F 9/046 Arrangement of recording means in or on check-out counters record carriers or readers per se G06K
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G06K 2207/1012 Special detection of object
• CPC Class Codes: G06K 7/10544 by scanning of the records by radiation in the optical part of the electromagnetic spectrum
• CPC Class Codes: G06K 7/10564 Light sources
• CPC Class Codes: G06K 7/10574 Multiple sources
• CPC Class Codes: G06K 7/10613 by rotation, e.g. polygon
• CPC Class Codes: G06K 7/10623 Constructional details
• CPC Class Codes: G06K 7/10693 for omnidirectional scanning
• CPC Class Codes: G06K 7/10712 Fixed beam scanning
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10782 Slot readers
• CPC Class Codes: G06K 7/10792 Special measures in relation to the object to be scanned
• 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: G06Q 20/208 Input by product or record sensing, e.g. weighing or scanner processing
• CPC Class Codes: G06Q 30/06 Buying, selling or leasing transactions
• CPC Class Codes: G06V 10/141 Control of illumination
• CPC Class Codes: G07G 1/0036 Checkout procedures
• 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 3/00 : Alarm indicators, e.g. bells
• CPC Class Codes: G07G 3/006 : False operation

Abstract

A laser beam generation system having an integrated coherence reduction mechanism. The system includes: a flexible circuit having a first end portion and a second end portion; a laser diode mounted on the first end portion of the flexible circuit, for producing a laser beam having a central characteristic wavelength; diode current drive circuitry for producing a diode drive current to drive the laser diode and produce said laser beam; and high frequency modulation (HFM) circuitry also mounted on the first end portion of the flexible circuit, for modulating the diode drive current at a sufficiently high frequency to cause the laser diode to produce a laser beam having a spectral side-band components about the central characteristic wavelength, and thereby reducing the coherence as well as coherence length of the laser beam.

Claims

1. A laser beam generation system having a integrated coherence reduction mechanism, comprising:

a flexible circuit having a first end portion and a second end portion;

a laser diode mounted on said first end portion of said flexible circuit, for producing a laser beam having a central characteristic wavelength;

diode current drive circuitry for producing a diode drive current to drive said laser diode and produce said laser beam; and

high frequency modulation (HFM) circuitry, mounted on said first end portion of said flexible circuit, for modulating said diode drive current at a sufficiently high frequency to cause said laser diode to generate spectral side-band components about said central characteristic wavelength, and thereby reducing the coherence as well as coherence length of said laser beam.

2. The laser beam generation system of claim 1, wherein said diode current drive circuitry is mounted on said flexible circuit.

3. The laser beam generation system of claim 1, wherein said diode current drive circuitry is mounted on a printed circuit board that is interfaced with said second end portion of said flexible circuit.

4. The laser beam generation system of claim 1, wherein said diode current drive circuitry is mounted on said second end portion of said flexible circuit.

5. The laser beam generation system of claim 1, wherein said laser diode is a diode selected from the group consisting of a visible laser diode and an IR laser diode (IR-LD)

6. The laser beam generation system of claim 1, in combination with an optical beam multiplexing (OMUX) module for receiving said laser beam as input beam, a generating as output, a plurality of laser beam components that are recombined to produce a composite laser beam having substantially reduced coherence for use in illumination applications where a substantial reduction in speckle pattern noise is achieved.

7. The laser beam generation system of claim 6, wherein said OMUX module comprises:

a single glass plate bearing having an input surface and an output surface, and reflective and semi-reflective coatings provides on said input and output surfaces, so as to optically multiplex an input laser beam entering said input surface, into multiple spatial-coherence reduced output laser beams exiting from said output surface.

8. The laser beam generation system of claim 7, wherein said multiple spatial-coherence reduced output laser beams are planarized into a composite substantially planar laser illumination beam (PLIB) by a multi-cylinder planarizing-type illumination lens array disposed in close proximity said output surface.

9. The laser beam generation system of claim 7, wherein said OMUX module comprises:

a glass plate bearing mirror and semi-transparent reflective coatings, and deployable in a laser-despeckling PLIM so as to reduce (i) the coherence of the resulting planar/narrow-area illumination beam generated therefrom, and (ii) thus the amount of speckle pattern noise observed at said image detection array of an image formation and detection subsystem.

10. The laser beam generation system of claim 7, in combination with said OMUX module, and also a digital image detection array for detecting digital images of an object illuminated by said composite substantially planar laser illumination beam;

wherein the power of speckle pattern noise observed in a digital image of an object detected at said digital image detection array is substantially reduced when said digital image is formed using said substantially planar laser illumination beam.