Device for producing a laser beam of reduced coherency using high-frequency modulation of the laser diode current and optical multiplexing of the output laser beam

• US 7,770,796 B2
• Filed: 10/30/2007
• Issued: 08/10/2010
• Est. Priority Date: 11/24/2000
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Zhu, Xiaoxun, Veksland, Michael, Ren, Jie, Knowles, C. Harry, Xian, Tao, 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.
• Primary Examiner(s): Kim; Ahshik
• Application Number:
  US11/980,317
• Publication Number:
  US 20080156877A1
• Time in Patent Office: 1,015 Days
• Field of Search: 235/462.42, 235/462.41, 235/462.25, 235/454
• US Class Current: 235/454
• 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 despeckling device including a laser diode for producing a laser beam having a central characteristic wavelength. The device includes diode current drive circuitry for producing a diode drive current to drive said laser diode and produce said laser beam. High frequency modulation (HFM) circuitry modulates the diode drive current at a sufficiently high frequency to cause said laser diode to produce spectral side-band components about the central characteristic wavelength, and reducing the coherence as well as coherence length of the laser beam. An optical beam multiplexing (OMUX) module is provided for receiving the 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.

Claims

1. A laser beam despeckling device comprising:

a laser diode for producing a laser beam having a central characteristic wavelength, a coherence, and a coherence length;

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

a high frequency modulation (HFM) circuit for modulating said diode drive current at a sufficiently high frequency to cause said laser diode to produce spectral side-band components about said central characteristic wavelength, and reduce the coherence as well as coherence length of said laser beam; and

an optical beam multiplexing (OMUX) module for receiving said laser beam as an input beam, and generating as an output beam, a plurality of laser beam components that are recombined to produce a composite laser beam having substantially reduced coherence for use in one or more applications where a substantial reduction in speckle pattern noise is achieved.

2. The laser-despeckling device of claim 1, wherein said laser diode is selected from the group consisting of a visible laser diode (VLD) and an invisible laser diode such as an IR laser diode (IRLD).

3. The laser-despeckling device of claim 1, wherein said applications are selected from the group consisting of digital imaging, projection television, and photolithographic illumination operations.

4. The laser-despeckling device of claim 1, wherein said illumination beam is an illumination beam selected from the group consisting of planar, narrow-area and wide-area illumination beams.