Laser-array based digital illuminator

• US 6,102,552 A
• Filed: 10/18/1996
• Issued: 08/15/2000
• Est. Priority Date: 10/18/1996
• Status: Expired due to Term

• Current Assignee: Agilent Technologies, Inc., Hewlett-Packard Company (HP Inc.), Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Tullis, Barclay J.
• Primary Examiner(s): Sember, Thomas M.
• Application Number:
  US08/731,784
• Time in Patent Office: 1,397 Days
• Field of Search: 362/249, 362/252, 362/259, 362/235, 362/335, 362/800
• US Class Current: 362/249.06
• CPC Class Codes: G02B 27/09 Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for adapting the beam shape of a laser diode G02B19/0052; adapting the beam shape of an LED G02B19/0061; coupling into light guides using intermediate optical elements G02B6/4204; beam shaping specially adapted for lasers H01S3/005
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

This invention is a power efficient illuminator and illumination method that provides control of spatial distributions of power density, ray angles, wavelength(s), polarization and temporal behavior (even coherence) to meet specific design specifications across a prescribed target zone (i.e., line, area or volume). This invention utilizes an array (or set) of radiant power or energy sources which can be selected or varied in kind(s), form(s), size(s) number and arrangement. Ancillary reflective, refractive or diffractive optical elements may be used for additional control. The ancillary optics may be one or more shared single optic or may be one or more entire array(s) of elements matched to the array of sources. The ancillary optics may be refractive or reflective, passive or active, self-focusing, or diffractive (e.g., holographic, binary or multistep). The set of individual sources are systematically distributed spatially, and driven individually or together. Each source in the set has a controlled divergence, each emitting a narrowly divergent beam with the beam axes aligned parallel to one another, aligned to converge at a common point, or aligned to diverge from a common (virtual) point. The individual source emitters comprising the set can either be all identical to one another or be made different from one another in a spatially graded way to meet design objectives for specific distribution patterns. The set of sources can be made up of an assembly of otherwise independent sources or all manufactured together in a monolithic array in a common manufacturing sequence (although perhaps with controlled process gradients). The set of sources can be configured in an array, regularly spaced to form a spatial grid, irregularly spaced, or in combination. In a preferred embodiment, the set of sources (emitters) is a monolithic array of vertical cavity surface emitting laser diodes.

Claims

1. An illumination apparatus, comprising:

a plurality of light sources, spatially arranged in an array, each light source of the plurality for emitting coherent light rays confined to an associated region and directed towards a target zone,

wherein, when emitting the light rays, the associated region of each light source at least partially overlaps the associated region of at least one different light source at a portion of the target zone and the illumination of the target zone provides substantially uniform radiant power incident to the target zone without scanning the light rays.

2. The apparatus as set forth in 1, wherein the light sources are not mutually coherent.

3. The apparatus as set forth in 1, wherein the light rays from the light sources combine to form a substantially collimated illumination of the target zone.

4. The apparatus as set forth in 1, wherein the light sources are lasers.

5. The apparatus as set forth in 1, further comprising an optical element positioned between a particular one light source of the plurality of light sources and the target zone to provide control of the light emitted from the particular one light source.

6. The apparatus as set forth in 5, wherein the optical element provides control of light emitted from at least one light source of the plurality of light sources other than the particular one light source.

7. The apparatus as set forth in 1, wherein the array is a planar lattice.

8. The apparatus as set forth in 1, wherein the array is a lattice located upon a portion of a sphere.

9. The apparatus as set forth in 1, wherein the light sources are distributed about the array to form a uniformly spaced light source lattice.

10. The apparatus as set forth in 1, wherein the light sources are distributed about the array to form a non-uniformly spaced light source lattice.

11. The apparatus as set forth in 1, wherein the light sources are resonant cavity light emitting diodes.

12. The apparatus as set forth in 1, further comprising a prism positioned between a particular one light source of the plurality of light sources and the target zone to direct the light emitted from the particular one light source to the target zone.

13. An illumination method, comprising the steps of:

emitting light rays from each of a plurality of light sources spatially arranged in an array, each light source of the plurality emitting coherent light rays confined to an associated region and directed towards a target zone,

wherein, when emitting the light rays, the associated region of each light source at least partially overlaps the associated region of at least one different light source at a portion of the target zone and the illumination of the target zone provides substantially uniform radiant power incident to the target zone without scanning the light rays.

14. The method as set forth in 13, wherein the light sources are not mutually coherent.

15. The method as set forth in 13, wherein the light rays from the light sources combine to form a substantially collimated illumination of the target zone.

16. The method as set forth in 13, wherein the light sources are lasers.

17. The method as set forth in 13, further comprising the step of providing control of the light emitted from a particular one light source of the plurality of light sources using an optical element positioned between the particular one light source and the target zone.

18. The method as set forth in 17, further comprising the step of using the optical element to provide control of light emitted from at least one light source of the plurality of light sources other than the particular one light source.

19. The method as set forth in 13, wherein the array is a planar lattice.

20. The method as set forth in 13, wherein the array is a lattice located upon a portion of a sphere.

21. The method as set forth in 13, wherein the light sources are distributed about the array to form a uniformly spaced light source lattice.

22. The method as set forth in 13, wherein the light sources are distributed about the array to form a non-uniformly spaced light source lattice.

23. The method as set forth in 13, further comprising the step of using a prism positioned between a particular one light source of the plurality of light sources and the target zone to direct the light emitted from the particular one light source to the target zone.

24. The method as set forth in 13, wherein the light sources are resonant cavity light emitting diodes.

25. An illumination apparatus, comprising:

a plurality of light sources, spatially arranged in an array, each light source of the plurality for emitting coherent light rays confined to an associated region and directed towards a planar target zone,

wherein, when emitting the light rays, the associated region of each light source at least partially overlaps the associated region of at least one different light source at a portion of the planar target zone thereby reducing speckle from an illuminated target within the planar target zone without scanning the light rays.

26. An illumination method, comprising the steps of:

emitting light rays from each of a plurality of light sources spatially arranged in an array, each light source of the plurality emitting coherent light rays confined to an associated region and directed towards a planar target zone,

wherein, when emitting the light rays, the associated region of each light source at least partially overlaps the associated region of at least one different light source at a portion of the planar target zone thereby reducing speckle from an illuminated target within the planar target zone without scanning the light rays.