Method of and system for producing images of objects using planar laser illumination beams and image detection arrays

• US 6,629,641 B2
• Filed: 02/09/2001
• Issued: 10/07/2003
• Est. Priority Date: 06/07/2000
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Zhu, Xiaoxun, 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:
  US09/780,027
• Publication Number:
  US 20020117545A1
• Time in Patent Office: 970 Days
• Field of Search: 235/462.01, 235/472.01, 235/462.22, 235/462.24, 235/454
• 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 27/48 Laser speckle optics
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: H01S 5/02325 Mechanically integrated components on mount members or optical micro-benches
• CPC Class Codes: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence

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. 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 scanning 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. A system for illuminating an object and forming an image thereof, comprising:

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

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 an object illuminated by said composite substantially planar laser illumination beam is focused along said field of view and onto said image detecting array to form an image of said illuminated object.

2. The 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. The system of claim 2, wherein said plurality of substantially planar laser illumination beam components produced from said plurality of planar laser illumination modules are combined so that said composite substantially planar laser illumination beam has substantially uniform power density characteristics over the entire spatial extent thereof of said composite substantially planar laser illumination beam over the working range of said system.

4. The system of claim 3, wherein each said substantially planar laser illumination beam component is focused so that the minimum beam width thereof occurs at a point or plane which is the maximum object distance at which said system is designed to acquire images, and thereby compensating for decreases in the power density of said composite substantially planar laser illumination beam caused by the fact that the width dimension of said composite substantially planar laser illumination beam increases in length for increasing object distances located away from said imaging optics.

5. The system of claim 1, wherein said image formation and detection module and said planar laser illumination array are both contained in a system housing, and wherein a Laser Doppler Imaging and Profiling (LDIP) subsystem is also integrated within said system housing so as to work in cooperation with said image formation and detection module and said planar laser illumination array.

6. The system of claim 1, which further comprises a system housing having a first light transmission aperture, a second light transmission aperture, a third light transmission aperture and a fourth light transmission aperture;

wherein said first light transmission aperture is optically isolated from said second, third and fourth light transmission apertures;

wherein said field of view is projected through said first light transmission aperture;

wherein a pair of planar laser illumination beams are produced by said planar laser illumination array and projected through said second and third light transmission apertures so as to produce said composite substantially planar laser illumination beam; and

wherein a Laser Doppler Imaging and Profiling (LDIP) subsystem projects a pair of amplitude-modulated (AM) laser beams at different angles through said fourth light transmission aperture which is optically isolated from said first, second and third light transmission apertures.

7. The system of claim 1, which further comprises a system housing, in which said image formation and detection module and said planar laser illumination array are mounted.

8. The system of claim 7, wherein said system housing is hand-supportable.

9. The system of claim 7, wherein said system housing is mountable about a conveyor belt structure.

10. The system of claim 7, wherein said system housing is supportable above a counter-top surface.

11. The system of claim 10, wherein said counter-top surface is located at a retail-based point of sale (POS) station.

12. The system of claim 1, wherein said image detecting array comprises a linear array of electronic image detection cells, upon which the field of view of said imaging optics is focused.

13. The system of claim 12, wherein said linear array of electronic image detection cells are realized using charge-coupled device (CCD) technology.

14. The system of claim 1, wherein said field of view is aligned with and confined within the spatial extent of said composite substantially planar laser illumination beam.

15. The system of claim 1, wherein said planar laser illumination array comprises a pair of planar laser illumination subarrays mounted about said image formation and detection module, for producing at least a pair of substantially planar laser illumination beam components, so that said composite substantially planar laser illumination beam is aligned in a coplanar relationship with said field of view during object illumination and imaging operations.

16. The system of claim 15, which further comprises a system housing having a first light transmission aperture and a second set of light transmission apertures, and

wherein said image formation and detection module projects said field of view through said first light transmission aperture, and

wherein said pair of planar laser illumination arrays project said pair of substantially planar laser illumination beam components through said second set of light transmission apertures, and

wherein said second set of light transmission apertures are optically isolated from said first light transmission aperture so as to prevent laser beam scattering within said system housing.

17. The system of claim 1, which further comprises both far and near fields within the working range of said system, and wherein the principle of Gaussian summation of light intensity distributions is employed to produce said composite substantially planar laser illumination beam so that said composite substantially planar laser illumination beam has a power density across its width dimension, which is substantially the same for both far and near fields of said system.

18. A package identification and dimensioning system, comprising:

an image-based package identification subsystem for identifying packages by imaging bar code symbols on said packages and processing images of said bar codes as said packages pass by said package image-based identification and measuring system,

wherein said image-based package identification subsystem includes

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

a planar laser illumination array having a plurality of 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 light reflected off a package illuminated by said composite substantially planar laser illumination beam is focused along said field of viewand onto said image detecting array to form an image of the bar code symbol on said illuminated package, for use in subsequent image processing operations enabling the identification of the illuminated package by processing the image of the bar code symbol; and

a package dimensioning subsystem, operably associated with said image-based package identification subsystem, for capturing information about the dimensions of said package prior to said package being identified by said image-based package identification subsystem.

19. A system for illuminating an object and forming an image thereof, comprising:

a system housing having a first light transmission aperture, a second light transmission aperture and a third light transmission aperture, wherein said first light transmission aperture is optically isolated from said second and third light transmission apertures;

an image formation and detection module mounted in said system housing and having imaging optics with a field of view (FOV) focused at an image detecting array and projected through said first light transmission aperture; and

a planar laser illumination array mounted in said system housing and having a plurality of planar laser illumination modules for producing a plurality of substantially planar laser beam components which are projected through said first and second light transmission apertures and combined so as to produce a composite substantially planar laser illumination beam that has substantially planar spatial distribution characteristics that extend through said field of view so that laser light reflected off an object illuminated by said composite substantially planar laser illumination beam is focused along said field of view and onto said image detecting array to form an image of said illuminated object.

20. The system of claim 19, 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.

21. The system of claim 19, wherein said plurality of said substantially planar laser illumination beam components are combined so that said composite substantially planar laser illumination beam has substantially uniform power density characteristics over the entire spatial extent of said composite substantially planar laser illumination beam over the working range of said system.

22. The system of claim 19, wherein each said substantially planar laser illumination beam component is focused so that the minimum beam width thereof occurs at a point or plane which is the maximum object distance at which said system is designed to acquire images, and thereby compensating for decreases in the power density of said composite substantially planar laser illumination beam caused by the fact that the width dimension of said composite substantially planar laser illumination beam increases in length for increasing object distances located away from said imaging optics.

23. The system of claim 19, wherein a Laser Doppler Imaging and Profiling (LDIP) subsystem is also integrated with said system housing and configured to work in cooperation with said image formation and detection module and said planar laser illumination array.

24. The system of claim 19, wherein said system housing further includes a fourth light transmission aperture optically isolated from said first, second and third light transmission apertures;

and wherein a Laser Doppler Imaging and Profiling (LDIP) subsystem projects a pair of amplitude-modulated (AM) laser beams at different angles through said fourth light transmission aperture.

25. The system of claim 19, wherein said system housing is realized as a hand-supportable housing.

26. The system of claim 19, wherein said system housing is mounted about a conveyor belt structure.

27. The system of claim 19, wherein said system housing is supportable above a counter-top surface.

28. The system of claim 27, wherein said counter-top surface is located at a retail-based point of sale (POS) station.

29. The system of claim 19, wherein said image detecting array comprises a linear array of electronic image detection cells, upon which the field of view of said imaging optics is focused.

30. The system of claim 29, wherein said linear array of electronic image detection cells are realized using charge-coupled device (CCD) technology.

31. The system of claim 19, wherein said field of view is aligned with and confined within the spatial extent of said composite substantially planar laser illumination beam.

32. The system of claim 19, wherein said planar laser illumination array comprises a pair of planar laser illumination subarrays mounted on opposite sides of said image formation and detection module so that said composite substantially planar laser illumination beam is aligned in a coplanar relationship with said field of view during object illumination and imaging operations.

33. The system of claim 19, which further comprises both far and near fields within the working range of said system, and wherein the principle of Gaussian summation of light intensity distributions is employed to produce said composite substantially planar laser illumination beam so that said composite substantially planar laser illumination beam has a power density across its width dimension, which is substantially the same for both far and near fields of said system.