METHOD OF AND SYSTEM FOR PRODUCING DIGITAL IMAGES OF OBJECTS WITH SUBTANTIALLY REDUCED SPECKLE-NOISE PATTERNS BY ILLUMINATING SAID OBJECTS WITH SPATIALLY AND/OR TEMPORALLY COHERENT-REDUCED PLANAR LASER ILLUMINATION

• US 6,830,189 B2
• Filed: 06/15/2001
• Issued: 12/14/2004
• Est. Priority Date: 12/18/1995
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Kim, Steve Y., Zhu, Xiaoxun, Good, Timothy, Amundsen, Thomas, Naylor, Charles A., Knowles, Carl Harry, Jankevics, Andrew, Schnee, Michael D., Tsikos, Constantine J., Wirth, Allan, Dobbs, Russell Joseph
• Primary Examiner(s): Lee, Michael G.
• Assistant Examiner(s): Kim, Ahshik
• Application Number:
  US09/883,130
• Publication Number:
  US 20020043561A1
• Time in Patent Office: 1,278 Days
• Field of Search: 235/462-1-4, 235/472.01, 235/454
• US Class Current: 235/462.22
• 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 26/106 having diffraction gratings as scanning elements, e.g. holographic scanners holographic optical elements G02B5/32, holography G03H
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G06K 17/0022 arrangements or provisious 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 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 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• 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: G07G 1/0054 : with control of supplementary check-parameters, e.g. weight or number of articles
• CPC Class Codes: H01L 21/28575 : on semiconductor bodies comprising AIIIBV compounds
• CPC Class Codes: H01L 29/452 : on AIII-BV compounds
• CPC Class Codes: H01S 5/02325 : Mechanically integrated components on mount members or optical micro-benches

Abstract

Methods of and systems for illuminating objects using planar laser illumination beams having substantially-planar spatial distribution characteristics that extend through the field of view (FOV) of image formation and detection modules employed in such systems. Each planar laser illumination beam is produced from a planar laser illumination beam array (PLIA) comprising an plurality of planar laser illumination modules (PLIMs). Each PLIM comprises a visible laser diode (VLD, a focusing lens, and a cylindrical optical element arranged therewith. The individual planar laser illumination beam components produced from each PLIM are optically combined to produce a composite substantially planar laser illumination beam having substantially uniform power density characteristics over the entire spatial extend thereof and thus the working range of the system. Preferably, each planar laser illumination beam component is focused so that the minimum beam width thereof occurs at a point or plane which is the farthest or maximum object distance at which the system is designed to acquire images, thereby compensating for decreases in the power density of the incident planar laser illumination beam due to the fact that the width of the planar laser illumination beam increases in length for increasing object distances away from the imaging optics. Advanced high-resolution wavefront control methods and devices are disclosed for use with the PLIIM-based systems in order to reduce the power of speckle-noise patterns observed at the image detections thereof. By virtue of the present invention, it is now possible to use both VLDs and high-speed CCD-type image detectors in conveyor, hand-held and hold-under type imaging applications alike, enjoying the advantages and benefits that each such technology has to offer, while avoiding the shortcomings and drawbacks hitherto associated therewith.

Claims

1. An automated package identification and measuring system comprising:

a housing;

a planar laser illumination and imaging (PLIIM) based bar code reading subsystem disposed in said housing, for reading bar codes on packages passing below or near said system so as to identify said packages,

wherein said PLIIM based bar code reading subsystem includes

(i) an image formation and detection module having imaging optics with a field of view (FOV) focused at an image detecting array,

(ii) a planar laser illumination array having a plurality of planar laser illumination modules for producing a plurality of substantially planar laser beam components which are combined to produce a composite substantially planar laser illumination beam having substantially planar spatial distribution characteristics that extend through said field of view so that laser light, reflected off said packages illuminated by said composite substantially planar laser illumination beam, is focused along said field of view and onto said image detecting array to form images of said illuminated packages as said packages move past said PLIIM based bar code reading subsystem, and

(iii) an image processor for processing said images of said illuminated packages and reading one or more bar code symbols represented in each said image, so as to enable the identification of each illuminated package; and

a package dimensioning subsystem disposed in said housing, for capturing information about the dimensions of said packages prior to being identified by said PLIIM-based bar code reading subsystem.

2. The automated package identification and measuring system of claim 1, wherein each said planar laser illumination module comprises a visible laser diode (VLD), a focusing lens, and a cylindrical optical element arranged therewith to produce one of said plurality of substantially planar laser illumination beam components.

3. An object attribute acquisition and analysis system comprising:

a first subsystem for acquiring and analyzing, in real-time, the physical attributes of objects selected from the group consisting of (i) the surface reflectivity characteristics of said objects, (ii) geometrical characteristics of said objects, including shape measurement, (iii) the motion (i.e. trajectory) and velocity of said objects, and (iv) bar code symbol symbols, textual materials, or other information-bearing structures disposed on said objects,

wherein said first subsystem includes

(i) an image formation and detection module having imaging optics with a field of view (FOV) focused at an image detecting array, and

(ii) a planar laser illumination array having a plurality of planar laser illumination modules for producing a plurality of substantially planar laser beam components which are combined to produce a composite substantially planar laser illumination beam having substantially planar spatial distribution characteristics that extend through said field of view so that laser light, reflected off said objects illuminated by said composite substantially planar laser illumination beam, is focused along said field of view and onto said image detecting array to form images of said illuminated objects as said objects move past said first subsystem, and

a second subsystem for processing said images of said illuminated objects and reading one or more bar code symbols, textual material, or other information-bearing structures presented by each said image, so as to enable the identification of each illuminated object, for use in diverse applications including object identification, tracking, and/or transportation/routing operations.

4. The object attribute acquisition and analysis system of claim 3, wherein each said planar laser illumination module comprises a visible laser diode (VLD), a focusing lens, and a cylindrical optical element arranged therewith to produce one of said plurality of substantially planar laser illumination beam components.

5. An object attribute acquisition and analysis system comprising:

a planar laser illumination and imaging (PLIIM) based subsystem, including

(i) auto-focus/auto-zoom imaging optics with a variable field of view (FOV) focused at an image detecting array having height/velocity-driven photo-integration time control for capturing images of objects so that said captured images have constant image resolution (i.e. constant dpi) independent of the height of said objects; and

(ii) a planar laser illumination array having a plurality of planar laser illumination modules for producing a plurality of substantially planar laser beam components which are combined to produce a composite substantially planar laser illumination beam having substantially planar spatial distribution characteristics that extend through said field of view so that laser light, reflected off said objects illuminated by said composite substantially planar laser illumination beam, is focused along said field of view and onto said image detecting array to form images of said illuminated objects as said objects move past said object attribute acquisition and analysis system; and

(iii) an image processor for processing said images of said illuminated objects and reading one or more bar code symbols represented in each said image, so as to enable the identification of each illuminated object.

6. The object attribute acquisition and analysis system of claim 5, wherein each said planar laser illumination module comprises a visible laser diode (VLD), a focusing lens, and a cylindrical optical element arranged therewith to produce one of said plurality of substantially planar laser illumination beam components.

7. A planar laser illumination and imaging (PLIIM) based system comprising:

a planar laser illumination array (PLIA); and

an electronic image detection array which cooperates with said PLIA so as to effectively reduce speckle-pattern noise observed at said electronic image detection array by reducing or destroying either (i) the spatial and/or temporal coherence of planar laser illumination beams (PLIBs) produced by said PLIAs and directed onto a target, or (ii) the spatial and/or temporal coherence of the planar laser illumination beams (PLIBs) that are reflected/scattered off said target and received by an image formation and detection (IFD) subsystem employed in said PLIIM based system.

8. A unitary planar laser illumination and imaging (PLIIM) based package dimensioning and identification system comprising:

a Laser Doppler Imaging and Profiling (LDIP) subsystem for generating package dimension related information signals;

a camera control computer responsive to said package dimension related information signals, for generating digital control signals; and

an image formation and detection (IFD) subsystem responsive to said digital control signals, so that said PLIIM based package dimensioning and identification system can carry out its diverse functions in an integrated manner, wherein said diverse functions are selected from the group consisting of

(1) capturing digital images having (i) square pixels (i.e. 1;

1 aspect ratio) independent of package height or velocity, (ii) significantly reduced speckle-noise levels, and (iii) constant image resolution measured in dots per inch (dpi) independent of package height or velocity,

(2) automatic cropping of captured images so that only regions of interest representing the package or package label require image processing by an image processing computer, and

(3) automatic image lifting operations.