Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0033—Means for improving the coupling-out of light from the light guide
  • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
  • G02B6/0045—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it by shaping at least a portion of the light guide
  • G02B6/0046—Tapered light guide, e.g. wedge-shaped light guide
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21K—NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
  • F21K9/00—Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
  • F21K9/60—Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction
  • F21K9/61—Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction using light guides
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
  • F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
  • F21S41/10—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source
  • F21S41/14—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source characterised by the type of light source
  • F21S41/141—Light emitting diodes [LED]
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
  • F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
  • F21S41/10—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source
  • F21S41/14—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source characterised by the type of light source
  • F21S41/16—Laser light sources
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
  • F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
  • F21S41/10—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source
  • F21S41/14—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source characterised by the type of light source
  • F21S41/176—Light sources where the light is generated by photoluminescent material spaced from a primary light generating element
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
  • F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
  • F21S41/10—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source
  • F21S41/14—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source characterised by the type of light source
  • F21S41/18—Combination of light sources of different types or shapes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
  • F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
  • F21S41/20—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by refractors, transparent cover plates, light guides or filters
  • F21S41/24—Light guides
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
  • F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
  • F21S41/20—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by refractors, transparent cover plates, light guides or filters
  • F21S41/285—Refractors, transparent cover plates, light guides or filters not provided in groups F21S41/24 - F21S41/2805
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
  • G02B27/0905—Dividing and/or superposing multiple light beams
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
  • G02B27/0938—Using specific optical elements
  • G02B27/095—Refractive optical elements
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
  • G02B27/0938—Using specific optical elements
  • G02B27/0977—Reflective elements
  • G02B27/0983—Reflective elements being curved
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/1066—Beam splitting or combining systems for enhancing image performance, like resolution, pixel numbers, dual magnifications or dynamic range, by tiling, slicing or overlapping fields of view
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/12—Beam splitting or combining systems operating by refraction only
  • G02B27/123—The splitting element being a lens or a system of lenses, including arrays and surfaces with refractive power
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/12—Beam splitting or combining systems operating by refraction only
  • G02B27/126—The splitting element being a prism or prismatic array, including systems based on total internal reflection
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/14—Beam splitting or combining systems operating by reflection only
  • G02B27/149—Beam splitting or combining systems operating by reflection only using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
  • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
  • G02B6/0018—Redirecting means on the surface of the light guide
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
  • G02B6/0023—Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
  • G02B6/0028—Light guide, e.g. taper
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0066—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
  • G02B6/0068—Arrangements of plural sources, e.g. multi-colour light sources
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0066—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
  • G02B6/0073—Light emitting diode [LED]
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
  • F21S45/00—Arrangements within vehicle lighting devices specially adapted for vehicle exteriors, for purposes other than emission or distribution of light
  • F21S45/40—Cooling of lighting devices
  • F21S45/47—Passive cooling, e.g. using fins, thermal conductive elements or openings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V7/00—Reflectors for light sources
  • F21V7/0091—Reflectors for light sources using total internal reflection
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
  • F21Y2115/00—Light-generating elements of semiconductor light sources
  • F21Y2115/10—Light-emitting diodes [LED]
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B3/00—Simple or compound lenses
  • G02B3/02—Simple or compound lenses with non-spherical faces
  • G02B3/08—Simple or compound lenses with non-spherical faces with discontinuous faces, e.g. Fresnel lens
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/85—Packages
  • H10H20/855—Optical field-shaping means, e.g. lenses
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/85—Packages
  • H10H20/855—Optical field-shaping means, e.g. lenses
  • H10H20/856—Reflecting means

Definitions

• the present invention relates generally to, light sources, and more particularly to light collection/distribution systems that utilize one or more light- emitting diodes (LEDs).
• LEDs light- emitting diodes
• LEDs Light emitting diodes
• the LED prior art is less than satisfactory regarding the combination of the luminous outputs of a plurality of emitter-chips. Physical chip-adjacency can indeed produce a larger light source, but heat- removal limitations reduce the total luminance. Also, there is little continuity of illuminance between the adjacent emitters, leaving dark zones between the individual emitters.
• LEDs are available from a wide variety of suppliers, and in commercially available LEDs the emitters themselves have pronounced variations in luminance.
• some suppliers e.g., the OSRAM Corporation of San Jose, CA and the Cree Corporation of Santa Barbara, CA
• high-power LEDs from the Lumileds Corporation of San Jose, CA exemplify flip-chips, which have no wires or bonds that would otherwise block light emission in front. Even these, however, show great luminance variations across the emitter.
• the Luxeon I and Luxeon III LEDs by Lumileds can vary in luminance by a factor of ten from center to edge, with random patterns in between that differ from one chip to the next. Such undesirable patterning, whether on flip-chips or front-wired chips, can cause detrimental artifacts in the beams of collimating or condensing lenses. Although diffusers can be placed over such lenses, diffusers lose 15% of the light and give the beam a fuzzy edge. A more efficient method of source homogenizing, one that preserves sharp edges, would be a significant advance in illumination optics.
• the traditional optical approaches do not produce a rectangular or square uniform light source using such RGB light sources. It would be beneficial to have means of producing a light source combining more than three LED wavelengths. Additionally, it would be useful to have a means of producing such light sources where the chromaticity of the light source is adjustable.
• Embodiments of optical manifolds are described herein that provide the ability to efficiently combine a plurality of LED or other light source outputs into a single output that is substantially homogeneous, in a small, cost-effective package that may be made of a dielectric material.
• Optical manifolds are described that can be used to combine multiple LEDs of the same color to provide a high flux and high intensity output beam, or can be used to generate a multi- wavelength beam. For example, a red, green, and blue LED can be combined to make a "white" output.
• Embodiments are also disclosed that use a single LED or multiple LEDs and a remote phosphor coating arranged so that backscattered photoluminescence is recycled to the output.
• the optical manifolds use principles of nonimaging optics, and are designed to substantially alleviate luminance variations on the emitting surfaces of LEDs 1 and provide a substantially uniform light source.
• these optical manifolds can be used to produce a variety of non-square shaped light sources using square-shaped LEDs 1 including rectangular and asymmetric high flux light sources.
• These high-flux sources are useful for many applications such as for solid state lighting automobile headlamps. For example, for this application it is desirable to have a uniform rectangular LED-based light source with length to width ratio of 4 to 1. This is achievable with the optical manifold described herein.
• Solid-state lighting in general, and light-emitting diodes in particular, will find new applications through the benefits of the optical transformer described herein.
• an optical system for delivering the light of one or more blue chips to a spatially separate phosphor.
• a phosphor target could then be as small as the combined area of the separate chips, to maximize luminance.
• the phosphor layer is positioned remotely enough to be unaffected by the temperature variations of the LED itself.
• the optical transformer described herein relates generally to utilizing the principles of non-imaging optics to fulfill the above-discussed illumination- engineering needs, via the origination of a new type of optical manifold.
• the edge-ray principle of non-imaging optics sets forth the surfaces of minimal increase of source etendue, a central quantity of non-imaging optics.
• Etendue is the product of source area A 8 and the projected solid angle of the source's output, multiplied by the square of the refractive index n of the optical medium surrounding the source:
• An ideal optical system conserves etendue, so that the enlarged output area of an ideal collimator leads to its usefully high intensity within a narrow beam angle, while the small size of the focal spot of a solar concentrator leads to the usefully multiplied flux from its wide beam angle.
• the optical transformer described herein offers a new kind of optical manifold that provides etendue-limited illumination for collimated backlights, etendue-limited combination of plurality of light sources, and etendue-limited phosphor utilization.
• the useful fulfillment of these important tasks ⁇ by the optical transformer described herein marks a new stage of LED evolution.
• other photoluminescent materials besides phosphors such as the photoluminescent semiconductor AIInGaP, can be used with the optical transformer described herein more easily than they can be used directly on LEDs 1 .
• Some embodiments disclosed herein utilize total internal reflection only, and thus do not need metallic reflector coatings to be applied to their surfaces.
• Further embodiments comprise injection-molded sub-sections that are assembled into a complete manifold for producing a large "virtual chip" from the emission of several LED chips of smaller size.
• the virtual chip has better uniformity of luminance and color than the actual chips, and can be configured with usefully restricted angular output.
• controlled non-uniformity can be engineered along with such angular restrictions, enabling an intensity prescription to be met by placing the focal plane of a projection lens on the manifold output.
• FIG. 1A is a cross-sectional view of a thin-film LED with an adjacent compound parabolic concentrator (CPC) reflector;
• CPC compound parabolic concentrator
• FIG. 1B is a magnified cross-sectional view of part of Fig. 1A, showing the LED with a diffuse reflector in contact with the active epitaxy layer;
• FIG. 2A is a cross-sectional view of a thin-film LED immersed in optical contact with a 10° dielectric-filled CPC, showing a bottom part of the CPC;
• FIG. 2B is a cross-section of the dielectric-filled CPC of FIG. 2A, showing the entire 10° dielectric CPC;
• FIG. 2C is a cross-section of an optical manifold that incorporates the cross-section shown in FIGS. 2A and 2B, including a high-index CPC for high- efficiency light extraction and a low-index CPC for collimation;
• FIG. 2D is a cross-sectional view that shows the entire CPC shown partially in FIG. 2C;
• FIG. 3A is a cross-section of a thin-film LED immersed in a small hemisphere
• FIG. 3B is a cross-section of a thin-film LED immersed in a ball lens
• FIG. 3C is a cross-section of a thin-film LED immersed in a glob configuration typical of chip-on-board LEDs
• FIG. 4A is a cross-sectional view of two thin-film LEDs and a prism coupler
• FIG. 4B is a cross-sectional view of an optical manifold 44 that utilizes the prism coupler shown in FIG. 4A 1 including two thin-film LEDs immersed in smaller CPCs, each with a prism coupler, and a large CPC;
• FIG. 5 is a cross-section of a reflective optical manifold reflector for two
• LEDs each one having a CPC that feeds into a single, larger rectangular CPC, which provides the output;
• FIG. 6A is a cross-section of a 2:1 dielectric optical coupler
• FIG. 6B is a cross-section of a dielectric coupler similar to FIG. 6A, also including mixing rods;
• FIG. 6C is a cross-section of a hybrid optical manifold with CPC inputs and a cone with angularly restricted output in air;
• FIG. 6D is a cross-section of an optical manifold comprising cones or tailored mirrors and a multiplex lens
• FIG. 6E is a cross-section of a configuration similar to FIG. 6E, but utilizing a multiplex Fresnel lens;
• FIG. 6F is a cross-section of an optical coupler comprising a multiplex
• FIG. 6G is a face-on view of a hexagonally tiled optical manifold utilizing a plurality (e.g., 55) of circularly symmetric lenses, which can be implemented with any of the lenses shown in FIGS. 6A-6F, for example;
• FIG. 6H is a perspective view of the input side of a multiplex TIR lens
• FIG. 6I is a perspective view of the output side of the multiplex TIR lens of FIG. 6H;
• FIG. 7A is a side view of an etendue-limited flux-transfer from a domed
• FIG. 7B is a side view of an alternative etendue-limited flux-transfer from a domed LED into an image in air;
• FIG. 7C is a side view of an alternative etendue-limited flux-transfer from a domed LED into an image in air;
• FIG. 7D is a side view of a dual collimating lens with dichroic filter, also including a phosphor-coated surface
• FIG. 7E is a side view of another dual collimati ⁇ g lens with dichroic filter, also including a phosphor-coated surface
• FIG. 7F is a side view of another dual collimating lens with dichroic filter, including an off-axis LED and an off-axis phosphor system;
• FIG. 7G is a side view of another dual collimating lens with dichroic filter, including an off-axis LED triad array and an off-axis phosphor triad array system;
• FIG. 7H is a side view of another dual collimating lens for use with an off-axis LED and phosphor system
• FIG. 7I is a cross-sectional view of a cross-CEC with a remote phosphor
• FIG. 8A is a side view of an optical manifold comprising a plurality of square CPCs arranged in a 2x2:1 configuration
• FIG. 8B is an end view of an optical manifold comprising square CPCs in a 2x2:1 configuration
• FIG. 9A is a side view of a 2x4:1 optical manifold for eight LEDs and a
• FIG. 9B is another side view of a 2x4:1 optical manifold for eight LEDs and a 2:1 rectangular output, also comprising a mixing rod;
• FIG. 10A is a perspective view from the input side of a 4x4 optical manifold that feeds the output of sixteen blue LEDs through a blue-pass filter;
• FIG. 10B is a perspective view of the manifold of FIG. 10A from the output side, where the blue-passed light is condensed onto a patch of highly uniform phosphor;
• FIG. 10C is a close-up exploded perspective view of the phosphor, a monolithic ceramic, optically bonded to the CPC;
• FIG. 10D is a ray trace in a perspective view of the optical manifold of
• FIG. 10A showing how the phosphor's light output is returned by the filter, greatly increasing phosphor efficiency and luminance
• FIG. 10E is an exploded perspective view of a red semiconductor installed atop a green phosphor in the optical manifold of FIG. 1OA;
• FIG. 10F shows a manifold fed by both red and blue LEDs, also including a phosphor-coated surface
• FIG. 10G is another view of the phosphor end of a manifold fed by both red and blue LEDs;
• FIG. 10H is a close-up exploded view of a dielectric dome in which the monolithic ceramic is immersed, also including a phosphor-coated surface;
• FIG. 101 is a close-up exploded view from another viewing angle showing the dome's indentation to receive the phosphor
• FIG. 11A is a graph of the spectrum of light output from a blue LED, and also including the transmission curve;
• FIG. 11 B is a graph of the absorption and emission spectra of a yellow phosphor, and also including a transmission curve of a blue-pass filter;
• FIG. 11C is a graph of the absorption and emission spectra of a green phosphor, and also including the transmission curve of a red-pass filter;
• FIG. 12 is a cross-section of an angular compressor
• FIG. 13A is view of prior art, including a corner turner
• FIG. 13B is a ray trace of the prior art shown in FIG. 13A;
• FIG. 13C is a cross-section of an angle-rotator of the optical manifold.
• FIG. 13D is an alternative embodiment of an angle-rotator similar to that in FIG. 13C;
• FlG. 13E is a ray tracing of an angle-rotator such as shown in FIG.
• FIG. 14 is a cross-section of a source-shifter comprising two modified angle rotators
• FIG. 15A is a cross-section of a half-width source shifter
• FIG. 15B is a cross-section of a full-width source shifter
• FIG. 15C shows how the geometry of a light shifter can be changed to allow for different lateral shifts of light.
• FIG. 16 is a cross-section of a source twister
• FIG. 17 is a cross-section of a 2:1 optical manifold
• FIG. 18 is a perspective view of a rectangular 2:1 optical manifold with the profile similar to FIG. 17;
• FIG. 19 is a perspective view of a square 1:2 optical manifold with the profile similar to FIG. 17;
• FIG. 2OA is a cross-section of a 3:1 optical manifold with different input colors
• FIG. 2OB is another embodiment of the 3:1 optical manifold of FIG. 2OA, with more spacing between the LEDs;
• FIG. 21 is a cross-section of a 4:1 optical manifold with coplanar inputs having one angle-rotator each;
• FIG. 22 is a cross-section of another 4:1 optical manifold, with coplanar inputs having two angle-rotators each;
• FIG. 23 is a cross-section of an alternative embodiment of a 4:1 optical manifold, but with angular compressors for immersed inputs;
• FIG. 24 is a cross-section of an optical manifold arranged in an approximately circular arc;
• FIG. 25 is a cross-section of an optical manifold on an arc of decreasing radius
• FIG. 26A is a perspective view of a 2x2:1 optical manifold with intermediate angle-rotators
• FIG. 26B is a perspective view of the 2x2:1 optical manifold with intermediate angle-rotators shown in FIG. 26A;
• FIG. 26C is a view of a more openly branched 2x2:1 manifold;
• FIG. 26D is a view of a 3x3:1 manifold;
• FIG. 27A is a perspective view of a 4x4:1 branched optical manifold
• FIG. 27B is another perspective view of the 4x4:1 branched optical manifold shown in FIG. 27A, viewed from another angle;
• FIG. 28A is a perspective view of a 4x4:1 twisted-branch optical manifold
• FIG. 28B is another perspective view of the 4x4:1 twisted-branch optical manifold shown in FIG. 28B, viewed from another angle;
• FIG. 29 is a perspective view of an alternative embodiment of an arbitrarily branched optical manifold;
• FIG. 30 is a perspective view of a luminance shifter
• FIG. 31 A is an exploded, perspective view of another embodiment of an optical manifold that defines a monolithic etendue-squeezer
• FIG. 31 B is a perspective view of the resulting monolithic etendue- squeezer shown in exploded view in FIG. 31A;
• FIG. 31 C is another perspective view of the monolithic etendue- squeezer shown in FIGS. 31 A and 31 B;
• FIG. 32 is a perspective view of a monolithic 9:1 etendue-squeezer;
• FIG. 33A is a cross-section of a luminance transfer duct with an optically inactive surface
• FIG. 33B is a cross-section of an angle-rotating luminance duct similar to the embodiment of FIG. 33A;
• FIG. 34 is a cross-section of an angle-rotating luminance duct that has symmetrically placed ports
• FIG. 35 is a cross-section of a 4:1 duct with an inactive surface
• FIG. 36 is a cross-sectional view of a bilaterally symmetrical duct with two inactive surfaces
• FIG. 37A is a cross-sectional view of a composite system comprising four joined ducts with the configuration of FIG. 35;
• FIG. 37B is a cross-sectional view of another embodiment of an optical manifold in a further composite system
• FIG. 37C is a cross-sectional view of another embodiment of an optical manifold in a composite system, also including a phosphor-coated surface;
• FIG. 38A is a cross-sectional view of a dielectric CPC illuminating another CPC
• FIG. 38B is a cross-sectional view of an alternate configuration of FIG.
• FIG. 39A is a cross-sectional view of an alternative optical manifold that includes dielectric CPCs 1 illustrating the drawbacks of joining two CPCs at
• FIG. 39B is a cross-sectional view of an alternative optical manifold that includes two dielectric CPCs as in FIG. 39A, illustrating how an air gap prevents rays from escaping;
• FIG. 40 is a cross-sectional view of an alternate configuration for utilizing phosphor back-emission
• FIG. 41 is a cross-sectional view of another alternate configuration as in FIG. 40, also including a phosphor-coated surface.
• FIG. 42 is a cross-sectional view of another alternate configuration of
• FIG. 41 also including a phosphor-coated surface
• FIG. 43 is a cross-sectional view of a free-space version of FIG. 42, also including a phosphor-coated surface
• FIG. 44 is a cross-sectional view of an alternate configuration that adds a combiner to FIG. 43, also including a phosphor-coated surface
• FIG. 45 is a cross-sectional view of an alternate configuration that includes an orthogonal three-color free-space combiner with the refracted output area of one source, not all three, to provide a multiwavelength output;
• FIG. 46 is a cross-sectional view of an alternate configuration that includes a orthogonal combiner as in FIG. 45 to provide a multiwavelength output, but with a four-prism filter arrangement;
• FIG. 47 is a cross-sectional view of an alternate configuration to provide a multiwavelength output that includes an orthogonal prism combiner with angularly narrow-output;
• FIG. 48 is a cross-sectional view of an alternate configuration that shows a parallel three-color combiner with angularly narrow output
• FIG. 49 is a cross-sectional view of an alternate configuration that includes a free-space parallel combiner with output area n times one input;
• FIG. 50 is a cross-sectional view of an alternate configuration that can be used to combine a plurality of LEDs of different colors to provide a multiwavelength light output, including a prism combiner with two lateral CPCs;
• FIG. 51A is a cross-sectional view of an alternate configuration that includes a prism combiner with three lateral CPCs arranged in parallel to combine light and provide a multiwavelength light output;
• FIG. 51 B is a cross-sectional view of a manifold that produces a multiwavelength output using different color LEDs, and a phosphor-coated surface;
• FIG. 51 C is a cross-sectional view of an alternate configuration of a manifold that produces a multiwavelength output using different color LEDs, and a phosphor-coated surface;
• FIG. 52 is a cross-sectional view of an alternate configuration of an optical manifold that includes a double-width luminance shifter
• FIG. 53A is a plan view of a triplex optical manifold
• FIG. 53B is a side view of the triplex optical manifold of FIG. 53A;
• FIG. 54A is a contour graph of the far-field intensity emitted from the manifold of FIGS. 53A and 53B;
• FIG. 54B shows the central horizontal and vertical profiles of the far- field intensity pattern emitted from the manifold of FIGS. 53A and 53B;
• FIG. 55 is a contour graph of the spatial output from the output face of the manifold of FIGS. 53A and 53B;
• FIG. 56A is a perspective view of another embodiment of a triplex optical manifold, along with three input LEDs, on a circuit board;
• FIG. 56B is a perspective view of the optical-manifold of FIG. 56A, also including a free-form beam-shaping lens;
• FIG. 56C is a perspective view of the optical-manifold and beam- shaping lens of FIG. 56B, and a ray trace of its output shining on a beam-shaping reflector;
• FIG. 57 is a perspective view that includes four such configurations as in FIG. 56C 1 forming an automotive lamp for example fulfilling a prescription;
• FIG. 58A is a perspective view of an asymmetric manifold for producing an exit aperture in the shape of a beam illuminance pattern approximately matching those of automotive headlamp lighting requirements; and
• FIG. 58B is another perspective view of the asymmetric manifold of FIG. 58A.
• FIG 59 shows the construction of a crossed CPC.
• FIG. 6OA is a side view of a crossed-CPC remote phosphor system.
• FIG. 6OB shows rays escaping from same.
• FIG. 61 is a direction-space diagram showing how corner rays are beyond the acceptance circle.
• FIG. 62A is a diagram of energy flow mathematics. [0149] FIG. 62B shows the wavelength composition of same. [0150] FIG. 62C is the remote-phosphor performance curve. [0151] FIG. 63A shows a 4:1 remote phosphor system with a round CPC. [0152] FIG. 63B is another view of same.
• FIG. 64A is a cross-section of a white-masked remote phosphor with increased luminance.
• FIG. 64B is a perspective view of same.
• FIG. 65A is a remote phosphor with separate blue and yellow outputs.
• FIG. 65B is a variant of same with a white output.
• FIG. 65C is a variant of same with coplanar LED and phosphor.
• FIG. 65D is a variant of same with coplanar LED and phosphor with separate blue and yellow outputs.
• FIG. 65E is a variant of same with coplanar LED and phosphor patch with white output.
• FIG. 66A shows the spectral filter characteristics of FIGs 65A, B, & D.
• FIG. 66B shows alternative spectral filter characteristics for same.
• FIG. 66C shows the spectral filter characteristics for FIG. 65C.
• FIG. 66D shows the spectral filter characteristics for.
• FIG. 65E shows the spectral filter characteristics for.
• FIG. 67 is a graph of the spectral transmittance of an actual filter.
• FIG. 68A is a view of a 10° square CPC feeding a 15° square CPC.
• FIG. 68B is a view of a rectangular cross CPC
• FIG. 69A shows a remote phosphor with cooled coplanar LED and phosphor patch, with coincident but mismatched blue and yellow outputs.
• FIG. 69B shows same with compensating diffuser.
• FIG. 69C shows same with smaller output mirrors.
• FIG. 70 shows a non-recycling remote phosphor system with spatially and angularly coincident blue and yellow outputs.
• Fig. 71 is a perspective view of a remote phosphor with 16 blue LEDs and 4 phosphors, all coplanar, generating a spatially and angularly uniform collective white output beam.
• FIG. 72A and FIG. 72B are perspective views of remote phosphor with cone and lens rather than large dielectric CPC.
• FIG. 73A is cross-section view of a side-emitting remote phosphor system where the LED and phosphor patch lie on approximately the same axis.
• FIG. 73B is a cross-section view of a remote phosphor system with spatially separated contiguous short and long wave output ports.
• FIG. 73C is an alternative embodiment of the side-emitting remote phosphor system of FIG. 73A.
• FIG. 74 shows a T-shaped remote phosphor system with controllable color temperature of its white output.
• FIG. 75 shows a similar system, but with LEDs and phosphor patch in the same plane.
• FIG. 76 shows an alternative embodiment of FIG. 75 where the two
• FIG. 77 is a perspective view of a remote phosphor system using the principles taught in FIG. 75 and having eight blue LEDs and four phosphor patches.
• FIG. 78 is a cross-section view of a remote phosphor system having an adjustable color temperature that uses two blue LEDs.
• FIG. 79 is a cross-section view of a remote phosphor system with adjustable color temperature that uses partial recirculation of the yellow light.
• FIG. 80 is a cross-section view of a variant of the same.
• angle rotator a device that delivers luminance from one plane to another lying at a tilt to the first
• dichroic filter a filter that has two distinct transmission peaks dome of LED an approximately spherical LED cover made of transparent dielectric materials edge-ray principle the foundational principle of non-imaging optics, whereby a defining set of rays from the edge of an aperture are guaranteed to be delivered to the edge of another aperture, but the first aperture is not imaged onto the second Etendue the optical manifestation of entropy, defined as the product of source area A s and the projected solid angle of the source's output, multiplied by the square of the refractive index n of the optical medium surrounding the source
• ITO indium tin oxide LED light emitting diode a direct converter of low-voltage direct current to light in a narrow spectral band
• Luminaire a light source and functionally associated light-control apparatus, such as a reflector or a shade luminance shifter a device that delivers luminance to a different transverse coordinate
• NA numerical aperture phosphor a photoluminescent material that emits light in response to external excitation, often continuing after the excitation ceases phosphor patch a component having a given size and shape that contains phosphor. It can comprise phosphor or phosphor dispersed in an encapsulant, such as a silicone fluid.
• the phosphor patch can also be made as a composite material where a phosphor layer (with or without an encapsulant) is deposited on a suitable transparent substrate, such as a sheet or film in a volume production process.
• PMMA polymethylmethacrylate the polymeric constituent of transparent acrylic plastic RIIR lens a lens system that has refractive (R) and internally- reflective (I) surfaces in the order specified SMS a method of optical design that generates a two-surface optical device that transforms two specified input wavefronts into two specified output wavefronts, such as disclosed in U.S. Patent Application 2004-0246606 and in U.S. Patents 6,639,733, 6,867,929, and 6,896,381 thin film LED an LED that comprises very thin layers and emits nearly
• an "optical manifold” resembles the exhaust manifold of engines.
• channels are provided that either combine multiple light outputs into a single output, or distribute a single output over space.
• This term can designate a device for fiber optic fan-in and fan-out, such as in U.S. Patents 6,850,684, 6,847,774, 6,832,032, 6,655,848, 6,556,754, and 6,549,710 by Simmons et al.
• This multi-input, multi-output function is an informational task that is distinct from the efficient distribution of illumination.
• optical manifold was used in U.S. Patent 4,362,361 by Campbell, et al., but therein this term denotes a partially reflective coating that repeatedly allows a small part of a laser beam to escape reflection as it tunnels inside a slab, so that multiple beams are made from one. This usage differs from what has become the conventional usage, in that "optical manifold” now denotes branching many-to-one light paths.
• U.S. Patent 6,186,650 discloses an "optical manifold" of branching waveguides, with numerous embodiments illustrated. It is believed that an actual ray tracing of these structures, however, would show considerable leakage, as shown by FIG. 19A and FIG. 19B in that patent. Moreover, it is believed that this prior art does not conserve etendue, giving outputs that are much weaker than the input. This is because the squared-off endings of the ports will cause much of the guided light therein to be reflected backwards.
• Etendue like entropy, is a measure of optical disorder, basically being the product of spatial extent and angular extent. Increasing the etendue of light can be considered as the optical equivalent of turning work into waste-heat, where the optical work would be the luminance of light-emission, and the waste- heat would be the useless dispersion of this light.
• An "etendue-limited" optical device is one that delivers light with nearly the original luminance, once inevitable reflections and scatterings are accounted for.
• the optical transformer described herein is etendue-limited, in that the input area-angle product is preserved for light passing through it.
• Some embodiments of the optical transformer described herein receive light from a plurality of sources to create a large, highly uniform synthetic source that may prove highly useful in the art of illumination.
• Other embodiments form distributed lighting systems, as in vehicle dashboards, that preserve both luminosity and etendue, enabling fewer LED sources to be necessary to accomplish the illumination task.
• CPC compound parabolic concentrator
• CEC compound elliptic concentrator
• NA ⁇ 1 critical angle
• This flexibility enables optical transformer embodiments described herein to address the entire span of applications of both light combining and light distribution, with maximal flux, something yet to be accomplished by the prior art.
• This flexibility is further exemplified by embodiments of the optical manifold disclosed herein comprising two opposing angle-rotators acting as luminance shifters, another useful component of systems with arbitrary branching patterns of distributed illumination.
• optical transformers are described herein that overcome this problem by providing inactive surfaces along the length of the device that can be used for points of injection.
• the inactive surfaces can be used as a means of holding the devices, and they can be freely modified into a wide range of shapes, without affecting the shape of the active surfaces of the device.
• the inactive surfaces are deliberately created by the pattern of ray distribution within the angle-rotator, providing an envelope of non-interaction with the light field, within which non-lossy attachments may be made.
• optical manifold that receives light from a plurality of solid-state sources and combines them into a single virtual-source output having little more etendue than the sum of the inputs.
• the output light has the chromaticity of their colorimetric mixture. Due to the reversibility of light, the same shape of manifold could be used to disperse the light from a single large solid-state source among multiple virtual sources.
• FIG. 1A is a cross-sectional view of an optical manifold including a thin-film LED 10 comprising a light-emitting layer 11, reflective means 12, and a window 13.
• the LED 10 is embedded in a protective transparent epoxy or gel 14.
• An example of such a gel is Nyogel OC431A by Nye Optical Products of Fairhaven, MA, with refractive index 1.46 and thixotropic viscosity keeping it in place.
• An external CPC reflector 15 is accurately situated on the surface of epoxy 14 so that it just straddles window 13 over LED 10, which is typically about a millimeter across.
• One advantage of the optical manifold described herein is that it allows more efficient cooling of larger (or multiple) LEDs.
• Thin-film LEDs such as the LED 10 shown in FIG. 1A, emit nearly 100% of their output flux from the top surface of the device. Such devices have been produced in the laboratory and have been shown to the public by, for example OSRAM Semiconductors of Regensburg, Germany, which has begun producing them commercially in red and yellow with green and blue by the middle of the year 2005.
• OSRAM Semiconductors of Regensburg, Germany, which has begun producing them commercially in red and yellow with green and blue by the middle of the year 2005.
• a variety of thin emitter technologies are currently proposed by OSRAM Corporation of San Jose, CA, including Indium Gallium Aluminum Phosphide (InGaAIP) and Indium Gallium Nitride (InGaN).
• FIG. 1A further shows source-point 11s emitting edge-ray 16, which just clears the upper edge of CPC 15. Also shown is edge ray 17e emitted horizontally, thereby intercepting the base of reflector 15, from which it is reflected into ray 17r, which in turn just clears the upper edge of CPC 15. The 45° design angle is shown. It applies to both direct ray 16 and reflected ray 17r. Double- arrow 18 denotes the width of the virtual source generated by CPC 15. Its width is 1/sin 45° times the width of emitting layer 11 , thus preserving ' etendue.
• FIG. 1A shows CPC 15 as a hollow metal reflector, it could as well be filled with a dielectric such as cast epoxy.
• FIG. 1B is a magnified view of the LED 10 of FIG.
• FIG. 1 A showing emitting layer 11 comprising thin (approximately 0.1 microns) active layer 11a situated in the middle, InGaN layer 11u above it, and layer 11b below it.
• Window 13 can be seen to have slanted edge 13w to prevent light-escape.
• FIG. 1 B further shows an approach to enhancing the luminous extraction efficiency of a top-emitting LED (or of a predominantly top-emitting LED) wherein electrically conductive reflective layer 12 also acts to power epitaxy layer 11 , with which it is in direct contact.
• Roughened interface 11 i is the contact surface. This roughening can be achieved on the epitaxy layer 11 by chemical etching or other well-known methods.
• the reflective layer 12 can be deposited thereupon by vacuum, sputtering, or other deposition methods.
• the material properties of reflector layer 12 must be precisely specified to match with the properties of the epitaxy layer. For example, where an electrically conductive reflective layer is needed, a metallic material is best, and its index must have the proper complex value to achieve a high diffuse reflectance. For a blue LED using an epitaxy layer of GaInN or GaN for example, the visible-wavelength index of refraction of both GaInN and GaN is about 2.54.
• Calculating the reflectance of such a metal layer involves using the complex index of refraction in the Fresnel-reflection equations, so that both the real and imaginary components of the index of refraction of a candidate material are critical.
• the reflectance for rays striking at a zero incidence angle can provide a metric for choosing appropriate materials.
• a suitable equation for carrying out such an analysis is:
• R [(N e pi-N s ) 2 +k s 2 ]/[(Ne P i+N s ) 2 +k s 2 ] where R is the reflectance at zero incidence at the interface of the epitaxy and the metal layer,
• N ep i is the index of refraction of the epitaxy
• N 3 is the real part of the index of refraction of the metal
• k s is the imaginary part of the index of refraction of the metal.
• Such a reflective layer may also be made of dielectric materials using multi-layer approaches, particularly the Bragg reflector, common to the industry.
• electrical conductive paths known as vias must be introduced somewhere through this otherwise non-conductive layer, in order to power the semi-conductor.
• the use of a dielectric layer however may increase the internal resistance of the device and therefore increase the internal heat generated for a given applied voltage.
• silver may be deemed a superior solution over a dielectric reflector as it performs well over a wide range of incidence angles and wavelengths.
• U.S. Patent 6,784,462 teaches how to make an "omni-directional" back reflector with very high reflectance for an LED by combining a quarter wavelength layer of Indium Tin Oxide (ITO) in front of a layer of silver.
• ITO Indium Tin Oxide
• the thin film approach in the '462 patent assumes that the silver and ITO layers are smooth, precluding any roughening of the bottom of the LED proper, known as the 'epitaxial layer' because it is made atop a substrate, by an atomic beam in a vacuum.
• a standard LED geometry achieving maximum extraction efficiency makes it imperative to have a roughened surface at the interface where the reflector is in contact with the epitaxial layer. This is needed to achieve high diffuse reflectance, which causes trapped light to be randomly redirected for another chance at escape.
• ITO has a much lower electrical conductance than silver, which may be a disadvantage for some designs.
• silver will lose its reflectivity if not properly protected from contact with air or corrosive materials (it is highly reactive with sulfur), so it must be sealed by suitable protective layer.
• suitable protective layer typically, if the silver is sandwiched between the epitaxial layer and a suitable substrate such as Germanium, then no noticeable degradation of this material takes place as it is hermetically sealed. If edge protection is required there are many suitable materials known to those skilled in this field of semi-conductor design.
• a study using a ray-tracing model showed that the introduction of a scattering coefficient of 100/mm into layer 11u gives an approximately 40% increase in efficiency for a SMD-type LED, where layer 11 u does not have any appreciable scattering and does not have a phosphor layer in contact with it. Similar improvements are seen for a dome type monochrome LED. If the scattering coefficient is increased to 200/mm, a very slight improvement is seen. Whereas beyond this level there is reached a point where the performance degrades from the maximum. The use of a means of scattering in the front layer typically does not have a beneficial effect on performance when it is used in conjunction with the roughened back-reflector approach already discussed. There is a very slight improvement to the extraction efficiency if a roughened-back reflector is used in combination with layer 11u having a 10/mm scattering coefficient. Beyond this level of front scattering the performance falls below either single approach.
• FIG. 2A is a cross-section of the bottom of a dielectric-filled CPC. As in FIG. 1A, the thin-film LED 10 is immersed in transparent dielectric 14.
• dielectric-filled CPC 20 Optically continuous with transparent dielectric 14 is dielectric-filled CPC 20, formed by a CPC surface 21 , which operates solely by total internal reflection, and thus not needing a reflective coating.
• the CPC 20 would be separately manufactured and optically bonded to transparent dielectric 14, just above thin- film LED 10.
• FIG. 2B is a cross-section of the dielectric-filled CPC of FIG. 2A, showing the entirety of the CPC 20, with parabolic profile 21 shaped for a 10° output angle, the widest possible for a CPC using only total internal reflection.
• Top edge 211 of profile 21 is the outer edge of virtual source 22.
• the dielectric medium within CPC 20 may continue rightward in alternative embodiments (not shown in FIG. 2) as exemplified by CPC 54 connecting with larger CPC 53 in FIG. 5.
• the CPC 20 could have a refractive index higher than that of the epoxy material comprising transparent dielectric 14 of FIG. 1 B.
• Jewelry-grade cubic zirconia for example, has a refractive index of 2.2, similar to diamond. Even if currently it may be more expensive than polymer plastic optics, such a high-index transparent material may in the future be economically available. It would be advantageous for forming a CPC that is optically bonded to a thin-film LED to form an embodiment of the optical transformer described herein. While the high index ( ⁇ 2.5) of titanium-dioxide films matches that of the LED material, the film's high absorptance makes it unsuitable in forming a CPC.
• FIG. 2C is a cross-sectional view of an alternative optical manifold that utilizes a variation of this approach, replacing the CPC 20 with two CPCs.
• a first CPC 2002 is in contact with an LED 2001 , and is made of a sol-gel material matched to the index of the semiconductor and second, upper CPC 2003 is made of a lower refractive index material, such as PMMA.
• the first CPC 2002 is designed to partially coilimate and fully flash the second CPC 2003, which performs further collimation.
• This arrangement shown in FIG. 2C greatly increases overall extraction of flux from the die. Because of this, the LED 2001 would have a specular reflecting layer on its bottom side, unlike the diffusely reflecting mirror in FIG. 1 B.
• Surrounding silicone material 2004, with a low refractive index of 1.4, is the initial mold for the casting of CPC -2002, thereafter providing structural support for small CPC 2002, alleviating stress upon its bond with the top surface LED 2001.
• CPC 2001 is designed for this index ratio of 2.5:1.4, operating entirely by total internal reflection. Its exit face is planar interface 2005 with larger CPC 2003. Edge rays 2006R and 2006L are shown being reflected by the top edge of CPC 2001 and then refracted by interface 2005 into 70° edge rays 2007R and 2007L. They are internally reflected by CPC 2003 into final collimated rays 2008R and 2008L, respectively. Adjacent to them are edge rays 2008E, originating from rays 2006R and 2006L being directly refracted through interface 2005 and then totally internally reflecting off the wall of CPC 2003.
• FIG. 2D is a cross-sectional view that shows the entire CPC 2003 shown partially in FIG. 2C, including the ultimate position of edge rays 2008E.
• An alternative embodiment of the device of FIGS. 2C and 2D is to include a thin high matching index layer at the interface between LED 2001 and CPC 2002.
• the matching index phosphor layer is deposited onto the LED via a method such as electrophoretic deposition (the migration of charged colloidal particles or molecules through a solution under the influence of an applied electric field usually provided by immersed electrodes, also called cataphoresis).
• electrophoretic deposition the migration of charged colloidal particles or molecules through a solution under the influence of an applied electric field usually provided by immersed electrodes, also called cataphoresis.
• One method is one which provides high contact area between the phosphor and the top surface of the LED.
• the index of refraction of LED, 2001 , the small CPC 2002, and the phosphor should be closely matched, preferably within minus 0.1. So for an InGaN LED, which has an index of refraction on the top inactive surface of 2.5, the phosphor and the material of the small CPC should have an index of refraction between 2.4 and 2.5.
• Embodiments based on this device do not use or need a short-pass filter, such as the short-pass filter 105 described below with reference to FIG. 10B, to trap back-scattered light from the LED. When the refraction indices are matched, light will be recycled between the phosphor and the LED back mirror.
• FIG. 3B is a cross-sectional view of an LED 10 immersed in a ball lens 33.
• FIG. 3C is a cross-sectional view of a thin LED 36 on the circuit board 37, immersed in an epoxy glob 38, its untailored shape solely a result of the characteristics of epoxies highly convenient for mass production. It disadvantageous ⁇ traps some light. This shape, however, is highly consistent in mass production, so that other elements of the optical transformer described herein could be shaped to bond with it.
• FIG. 4A is a cross-sectional view of a prism coupler 40 that has an interior angle adapted to the critical angle ⁇ c of the prism material.
• Thin LED 41 sends Lambertian emission across airgap 41a, wherein it is confined between upper edge ray 41 e and lower edge ray 41 L.
• Thin LED 42 emits across airgap 42a and enters prism 40, wherein its Lambertian emission becomes confined to half-angle ⁇ c , between upper edge ray 42e and lower edge ray 42L.
• the purpose of interior angle 4OA being 2 ⁇ c becomes apparent when ray 41 e is seen to internally reflect off air gap 42, to join ray 42L.
• FIG. 4B is a cross-sectional view of an optical manifold 44 that utilizes the prism coupler shown in FIG. 4A.
• the optical manifold 44 comprises a dielectric CPC 44c and a conjoined prism block 44b.
• the thin LED 45 is immersed in a dielectric CPC 45c, which is wider at airgap 45a, across which it shines Lambertian light into manifold 44, wherein refraction confines it to critical angle ⁇ c .
• a similar approach is used with LED 46, CPC 46c, and airgap 46a.
• the prism coupler then receives two inputs of radiation spanning an angle 2 ⁇ c, through 45a and 46a, and transforms them into a fully Lambertian pattern at 44b (about ⁇ 90° full angle).
• a CPC 44c expands from its width at block 44b to its exit face 44a. This enables all the light to exit as Lambertian emission 44e, forming a "virtual chip". An exit surface at 44b would trap light beyond critical angle ⁇ c, hence the use of CPC 44c.
• FIG. 5 is a cross-section of a reflective optical manifold for two LEDs, 51 and 52, as inputs, respectively having small CPCs 54 and 55 that feed into a single, larger rectangular CPC, 53, for the output.
• Reflective optical manifold 50 receives the light output of first LED chip 51 and second LED chip 52.
• the manifold 50 comprises an upper compound parabolic concentrator (upper CPC) 53 and lower compound parabolic concentrators (lower CPC) 54 and 55, which receive the light of chips 51 and 52, respectively.
• Dividing line 5Od delineates the input plane of CPC 53 as well as the output planes of CPCs 54 and 55.
• Output opening 56 emits the combined output of the two LEDs into about ⁇ 90°.
• edge ray 57 is the reflection by surface normal 58 of nearly horizontal rays from chip 51. After reflection at line 5Od, the edge ray 57 proceeds to the edge of output opening 58, represented by a dotted exit-line, whereupon it is reflected back to horizontal, unfortunately somewhat obscuring said dotted line.
• FIGS. 6A to 6I depict further embodiments of clustering.
• FIG. 6A is a cross-section of optical manifold 610, based on dielectric CPCs such as that in FIG. 2.
• Manifold 610 comprises input CPCs 611 and 612 and output CPC 613. LEDs are mounted at entry ports 611 L and 612L, and their combined output is formed at exit port 613E.
• Dividing line 610D is the boundary between input and output CPCs. The reversibility of light shows that there could be a large LED shining into port 613E, causing light to be emitted at ports 611 L and 612L.
• FlG. 6B is a cross-section of optical manifold 620, comprising input dielectric CPCs 621 and 622 and larger output CPC 623.
• Input CPC 621 also comprises mixing rod 621 M, just inward from source 621 L, having the minimum width possible for guided light. This helps erase non-uniformities in source 621 L, to ensure uniform luminance for exit port 623E.
• FIG. 6C is a cross-section of one embodiment of the optical manifold
• dielectric-CPC input manifolds 621 and 622 comprising dielectric-CPC input manifolds 621 and 622, and tailored mirror
• FIG. 6D is a cross-section of another embodiment of the optical manifold 630, comprising reflective input cones 631 and 632, an output cone 633, and a lens 634.
• the light from LEDs 631 L and 632L are combined at output port
• FIG. 6E is a cross-section of still another embodiment of the optical manifold 640, comprising reflective input mirrors 641 and 642, an output mirror
• Fresnel lens 643 643, and a Fresnel lens 644.
• the light from LEDs 641 L and 642L are combined at an output port 643E.
• the thickness of the Fresnel lens 644 is exaggerated for clarity and in actual practice could be even thinner.
• FIG. 6F is a cross-section of still another embodiment of the optical manifold 650 comprising input TIR lenses 651 and 652 and an output TIR lens
• Input LEDs 651 L and 652L have their outputs combined at focal zone 653E.
• FIG. 6A-6E can be realized in either rectangular or circular symmetry.
• TIR lenses are inherently circularly symmetric, requiring some trimming for them to tessellate into arrays.
• FIG. 6G is a plan view of a multiplex lens 660, comprising 55 hexagonally trimmed circularly symmetric input means, as exemplified by FIGS.
• Each lens 661 focuses on an LED 662.
• FIG. 6H is a perspective view from the input side of optical manifold
• FIG. 6I is a perspective view of the optical manifold 670 of FIG. 6H from the other side, showing output TIR lens 673 and exit zone 673E.
• the large output dielectric CPC 610 in FIG. 6A can be replaced by the large trimmed TIR lens 653 of FIG. 6F.
• the output image is formed in air.
• This later configuration has an advantage in that the overall optical system is shorter in length and in some instances the TIR Lens may be easier and less expensive to mold than a long CPC or cross-CPC.
• the parts can either be molded as separate pieces and bonded together or be molded as one piece.
• the embodiments of optical manifolds shown have utilized thin, generally flat LEDs as input sources, and many depend upon placing a flat input of the optical manifold close to the flat emitting chip.
• a domed LED such as depicted in FIG. 3A, could be used as input only by the TIR lens of FIGS. 6F through 6I.
• FIG. 7A is a side view of an etendue-limited flux-transfer from a domed LED into an image in air.
• FIG. 7A shows a high-power LED package 700, comprising a base 701 , an emitting chip 702, and a transparent dome 703.
• a solid-dielectric dual lens 710 comprises a lower lens 711 and an identical upper lens 712, oppositely oriented and joined along line 710D, both lenses being circularly symmetric about axis 710A.
• the lower lens 711 comprises a central hyperbolic lens 711h and a surrounding generalized-Cartesian-oval reflector 71 1t, which collimates light coming through central cylinder 711c.
• Hyperbolic lens 711 h acts as an inlet, being focused on the center of LED chip 702.
• Upper lens 712 comprises central hyperbolic lens 712h and surrounding totally internally reflecting surface 712t. Light converges with ⁇ 90° on chip image 710E, from which another optical manifold could receive input light.
• Exemplary chief ray 715 has polar angle ⁇ from chip 702 and equal polar angle ⁇ ' at image 710E. When such a lens is precisely made and positioned, the etendue of image 710E does not increase much over that of the source, and source-luminance inhomogeneities are washed out, in that points on the image receive light from many points on the source.
• FIG. 7B is a side view of an alternative etendue-limited flux-transfer from a domed LED into an image in air.
• FIG. 7B shows a cross-section of a 2- facet dual TIR lens 720, mounted on an LED package 700.
• a lower TlR lens 721 surrounds the dome 703 and collimates the light of chip 702, sending it across dividing plane 72Od into the upper TIR lens 722, which in turn focuses it onto exit image 720E.
• the lens 720 is circularly symmetric about axis 720A of the LED package 700.
• An exemplary chief ray 725 subtends equal angles ⁇ and ⁇ ' with axis 720A.
• the optical accuracy of the manufacturing of this preferred embodiment must be high for image 720E to have little more etendue than chip 702. There will be an increase in area of image 720E from that of chip 202, which is proportional to the square of the index of refraction of the material of dome 703 in which LED 702 is embedded.
• FIG. 7C is a side view of SMS-designed RIIR lens 730, rotationally symmetric about a central axis 730a, with an equatorial plane 73Od dividing it into a lower lens 731 and an upper lens 732.
• the central lens 731c collects upward going light from LED chip 702 and collimates it into the central lens 732c, which in turn focuses it onto exit image 73Oe.
• Surrounding the central lens 731c is a bell- shaped surface 731 e, shaped to distribute light from the chip 702 over the totally internally reflecting surface 732r, which collimates it onto the .
• lens 730 is an RIIR lens.
• the continuity of the surfaces of lens 730 means that square LED chip 702 will have a square image at 730E, with very little etendue increase.
• FIG. 7D is a cross-sectional view through dual-lens system 740.
• the LED package 700 comprises the base 701 , the blue-emitting chip 702 (also shown in plan view at right), and the gel-filled dome 703.
• a silicone lens 742 Optically coupled to it in turn is a silicone lens 742, of a refractive index 1.34.
• lens-system 740 In the equatorial plane of lens-system 740 is a blue-pass dichroic filter 743, the recycling purpose of which is discussed below in FIG. 11. Atop it is a silicone lens 744, with form substantially identical to that of lower silicone lens 742. An uppermost lens 745 is identical in form to lower lens 741 , except for the addition of dome 745d, within which is immersed a remote phosphor 746 (also shown in plane view at right). Silicone lenses 742 and 744 can be seen acting in concert to direct ray 747 by total internal reflection within lenses 741 and 745, respectively. Ray 748 is emitted at angle ⁇ from centerline 749, and strikes phosphor 746 at equal angle ⁇ '.
• FIG. 7E is a side view through a dual-lens system 750, similar in function to that of FIG. 7D, with a similar LED.
• the gel-filled dome 703 is optically bonded to lower lens 751 , comprising internally reflecting an outer profile 751t, an inner collimat ⁇ ng lens 751c, and an optically inactive cylindrical wall 751w.
• Blue- pass dichroic filter 753 is in the equatorial plane of system 750.
• An inverted upper lens 755 is identical in form to lower lens 751 , but with the addition of dome 755d, in which phosphor 756 is immersed.
• Phosphor 756 is also shown to the right in plan view, as is the blue-emitting chip 702.
• the ray 758 is emitted at angle ⁇ with respect to a central symmetry axis 759, and strikes phosphor 756 with equal incidence angle ⁇ '.
• FIG. 7F is a side view through a dual-lens system 760, which is similar to the dual lens shown in Fig. 7E.
• an LED 766 is displaced off to the side of a device axis 777 so that one edge of the LED 766 is on axis 777.
• the phosphor layer 765 is located at the imaged focal position of lens 760 but on the opposite side of device axis 777 from that of LED 766.
• the dual lens 764 sharply images LED 766 onto the phosphor layer 765, whereupon some rays are directed into solid dielectric optic 762, and others are backscattered to filter 761.
• the filter 761 redirects and images all backscattered rays onto imaged focal position at the same height as phosphor layer 765, but on the opposite side of the axis of the device. These rays are directed into solid dielectric optic 762, whereupon they are directed from the device in a pattern. The final optic 762 will mix the bluish white and the yellow colors coming out of 765 into a uniform white color. Ray 763 illustrates the key principle associated with this embodiment.
• the dual lens 764 is designed through application of the SMS design methods. This device theoretically has a lower potential luminance than the embodiment in FIG. 7E as the virtual area of the source is larger. However, it has an advantage over the approach employed in FIG. 7E in that there is only a single re-cycling of the back-scattered rays before it can exit the device.
• FIG. 7G is a similar optical system to the one described in FIG. 7F.
• the single LED and single phosphor target is replaced with a triad of LEDs 775 and a triad phosphor target 774.
• the principle and operation of the device is similar to the device shown in FIG. 7F.
• the dual lens 773 sharply images LEDs 775 onto the phosphor targets 774, whereupon some rays are directed into solid dielectric optic 776, and other rays 772 are backscattered to filter 771.
• the filter 771 redirects and images backscattered rays onto spaces opposite the phosphor targets 774.
• FIG. 7H shows an embodiment that uses the same principle of single recirculation as the embodiments shown in FIGS. 7F and 7G but with a slightly different optical architecture.
• a filter 787 is embedded on its entire face by the bottom and top halves of an optic 782.
• Each half of the optic 782 has an outer solid dielectric TIR element 785, and an inner pair of refractive lenses 786 and 784 with an air gap between them.
• Interface 783 can have a secondary dielectric optic attached to it such as 762 of FIG. 7F, to extract the direct and recycled rays.
• FIG. 7I is a cross-section of a remote phosphor system 790, comprising LED chip 791 , a high-index compound elliptical concentrator (CEC) 792, and a high-index phosphor layer 793.
• CEC compound elliptical concentrator
• FIG. 7I is a cross-section of a remote phosphor system 790, comprising LED chip 791 , a high-index compound elliptical concentrator (CEC) 792, and a high-index phosphor layer 793.
• CEC compound elliptical concentrator
• This embodiment includes a specular reflector at the rear of LED 791 , preferably of silver or the hybrid silver/lTO omnidirectional reflector described in U.S. Patent 6,784,462 which is incorporated herein by reference in its entirety. This will reflect the phosphor's rearward emission with good efficiency, helping to nearly double its front-side luminance.
• Figures 1A through 2D concern the gathering of light for the optical transformer described herein. They show two-dimensional profiles acting on rays running in the plane of the Figures. In some practical embodiments a 3- dimensional system is formed by extruding such a profile orthogonally to its plane. The thickness of this extrusion distance is typically equal or slightly larger than the width of the square chip.
• FIGS. 8A, 8B, 9A, 10A and 1OB Critical to high system efficiency is the use of a transparent material with suitably low absorptance, because of the multipass nature of the passage of light within these embodiments.
• a transparent material with suitably low absorptance, because of the multipass nature of the passage of light within these embodiments.
• polycarbonate a routinely employed injection-molded plastic, has so much absorption that these embodiments will have serious losses, whereas acrylic does not.
• FIG. 8A is a perspective view of optical manifold 80, a dielectric-filled 2x2:1 multi-CPC embodiment. It comprises four input cross-CPCs 81 and-output cross-CPC 82, all square in cross-section, as seen with dividing line 8Od.
• the cross-section of each of these four cross-CPCs 81 is similar to that of FIG. 2B, so that immersed LEDs 83 will have all their light sent across plane 80d into cross- CPC 82.
• FIG. 8B is another perspective view of optical manifold 80, also showing exit surface 84, which must connect to another device of similar refractive index, else some of the concentrated light will be returned by internal reflection. It is possible to join manifold 80 with some of the embodiments to be shown below.
• FIG. 9A is perspective view of a 2x4:1 optical manifold 90, comprising a plurality of input cross-CPCs 91 that receive light from a corresponding plurality of immersed LEDs 92, a rectangular mixing section 93 that receives the light from the plurality of cross-CPCs 91 , and a rectangular output cross-CPC 94 that receives light from the rectangular mixing section.
• FIG. 9B is another perspective view of the manifold 90 shown in FIG. 9A 1 also including an approximately rectangular output surface 95 from the output cross-CPC 94.
• the geometry of the mixing section 93 is detailed in Fig 68B.
• the high-index CPC arrangement of FIG. 2C could be implemented with a silicone layer 2004 expanded to comprise multiple indentations to form multiple mofds for high-index CPCs to go over plurality of LEDs.
• the sol-gel process of high-index casting can thus accommodate many different embodiments of the optical transformer described herein.
• 10A is a perspective view of a 4x4:1 optical manifold 100, comprising a plurality of (in this embodiment sixteen) square dielectric input cross- CPCs 101 , a corresponding plurality of immersed LEDs 102 connected respectively to the cross-CPCs, and an approximately square output dielectric cross-CPC 103 coupled to collectively receive the light output from each of the cross-CPCs. Also shown is an immersed square filter 105, installed for the case of blue LEDs 102. In some embodiments, square filter 105 would be a blue-pass reflector applied across the input face of output CPC 103, then optically joined to the array of input cross-CPCs 101.
• Such a blue-pass reflector can be constructed in several ways well known to those skilled in this art, such as deposition of thin film multi-layer dielectric or other materials onto a suitable substrate, and through single or multi-layer reflection or transmission holographic coatings.
• deposition of thin film multi-layer dielectric or other materials onto a suitable substrate and through single or multi-layer reflection or transmission holographic coatings.
• two hollow reflective CPCs are used face-to-face to collimate light into a narrow-band spectral filter and then condense the filtered light.
• Embodiments of the optical transformer described herein utilize a dielectric CPC instead of a hollow CPC.
• FIG. 10A has a plurality of input CPCs rather than a single CPC.
• the condenser CPC, 103 has a phosphor target, 106.
• Condenser CPC 103 combines and homogenizes the input from sixteen LEDs onto a single exit surface on which phosphor target 106 resides.
• 10A 1 also not disclosed in Miles et at., is the function of filter 105, to reflect the back emission of phosphor 105, as shown in FIG. 10D. This is the recycling principle of certain embodiments of optical transformer described herein, which is believed to be a novelty.
• FIG. 10B is another perspective view of the optical manifold 100 shown in FIG. 10A, and in addition comprising an approximately rectangular exit face 104.
• FIG. 10C is a close-up view of exit CPC 103 at exit face 104, showing thin phosphor layer 106 exploded away from its actual position installed on 104.
• the phosphor layer receives the entirety of the immersed Lambertian optical output of cross-CPC 103.
• the advantageously uniform summation of light from blue LEDs 102 suffers no uniformity lost due to fluctuations or malfunction of any one LED.
• no wavelength binning of individual LEDs is required, so that quality control suffices that keeps constant the average center wavelength of any of the plurality of LEDs.
• the optical manifold shown in FIGS. 10A, 10B and 10C makes possible further advantages that flow from the phosphor configuration shown in FIG. 10C and that are not obtained with phosphor layers conventionally applied to individual blue chips.
• the blue chip receives a drop of a slurry of powdered phosphor in a semi-fluid binder. The drop dries (or is UV-cured) after being deposited on the blue chip during manufacturing.
• the disadvantages of the conventional approach are numerous.
• the deposition of a thin, controlled-thickness conformal layer of phosphor is extremely difficult to achieve onto the surface of a 1-mm high-powered LED emitter, which is believed to be a consequence of the materials used in the manufacture of the LED, the small size of its deposition surface and the fact that many of the techniques available for depositing a constant thickness layer on the emitting surface could possibly damage the LED.
• the phosphor layer is subject to high heat conditions because it is proximate to the LED, which can lead to accelerated thermal degradation of the coating or to physical damage to the phosphor/LED interface by forces arising from mismatched thermal expansion.
• the phosphor spectral emission curve discussed in connection with FIGS.
• FIG. 10C shows how the optical transformer described herein directly utilizes the phosphor after it is baked into a ceramic, as a large thin sheet of uniform thickness, such as 25-60 microns. A conveniently large piece could then be laser-scored or otherwise cleaved into pieces the size of layer 106, for example, in the range of 4-6 millimeter on a side. Larger pieces of phosphor of the same thickness could of course be used in larger optical manifolds for greater white-light luminosity. This method offers high uniformity in both luminance and color temperature, due to the much greater control of phosphor thickness and the lack of thermal cycling.
• FIG. 10D is ray tracing within the optical manifold 100 of FIGS. 10A, 10B, and 10C, illustrating the function of blue-pass filter layer 105, which is installed across the input face of output cross-CPC 103.
• Blue light from LEDs 102 passes through blue-pass filter layer 105 and reaches phosphor layer 106.
• Phosphor layer 106 emits an exemplary yellowish Lambertian-distributed ray 110r.
• the reversibility of optics means that cross-CPC 103 will compress the full angular range of the Lambertian emission, with representative ray 110r, of the interior side of phosphor layer 106.
• This combination of uniform blue illumination and a large photoluminescent layer is a novelty.
• a photoluminescent semiconductor such as a slice from a wafer of AIInGaP, to generate red light when illuminated by blue light. Since this material is transparent, it can be overlaid over a green phosphor and used instead of a yellow phosphor. Using a green phosphor can be advantageous when the quantum efficiency of the semiconductor is more than that of the yellow phosphor.
• FIG. 10E shows an example of such a configuration, showing the large CPC 103 with the exit face 104. A green phosphor 106P bonds thereupon and thinner red semiconductor layer 106S is installed atop it.
• FIG. 10F is a perspective view of a manifold 1000 comprising sixteen small CPCs 1001 feeding large a CPC 1003 through a planar filter 1005.
• four of the LEDs 1002R are red and the remaining twelve LEDs 1 1002B, are blue.
• FIG. 10G is another view of manifold 1000, showing green phosphor 1006 at the exit plane of large CPC 1003.
• a filter 1005 is shown comprised of a smaller red- pass filter 1005R and an L-shaped blue-pass filter 1005B.
• the filter 1005R lies over the four red LEDs 1002R, while filter 1005B lies over the twelve blue LEDs 1002B.
• This composite filter has recycling action just as shown by ray 110r in FIG. 10D.
• FIG. 10H is an exploded view similar to FIG. 10C, but adding an optical system that increases light extraction from the phosphor.
• FIG. 10H shows dielectric cross-CPC 103, monolithic ceramic phosphor 106, and dielectric hemisphere 108, which fits over the phosphor.
• FIG. 101 is another view of this fit, also showing the equatorial surface 108'
• the hemisphere 108 including a square indentation 109 that receives phosphor 106 and is optically bonded thereto.
• This arrangement increases light extraction by generating a magnified image of the phosphor. It is believed that such a dome will be less useful, however, when phosphor scattering is high. In that case, light trapped by the flat phosphor layer will be re-scattered and recycled via interaction with the filter 105 or 1005, which may be a blue-pass or short-pass bandpass filter, until it is either extracted or absorbed. If the short- pass filter is properly designed it should have a reflectance of 0.99 and have negligible absorptance.
• a flat protective cover of a suitable material is typically provided to protect the phosphor layer. Suitable materials include epoxy, PMMA, polycarbonate, for example, and other materials with a lower index of refraction than the phosphor.
• 11A is a graph of the output of the filter 105 in a spectrophotometric plot 110, comprising a horizontal wavelength scale 111 spanning the extremes of the visible spectrum, from 400 to 800 nanometers.
• a vertical scale 112 plots the relative intensity or transmittance.
• a plot line 113 shows the spectral transmittance of an example of a short-pass filter serving as blue-pass filter 105 of FIG. 10A.
• An upper line 113h is at nearly 100%, since filter 105 typically has a refractive index only a slightly lower than that of an injection moldable plastic such as polycarbonate.
• one suitable material for such a filter is a PYREX wafer.
• FIG. 11A graphs a transmittance plot 113 that shows an abrupt cliff 113c, between 485nm on the left and 495nm on the right.
• Short-pass filters having abrupt changes in transmittance and reflectance plots are commercially available, over a wide range of center wavelengths, such as from JDS Uniphase Corporation of Santa Rosa, CA. Suitable short-pass filters have a high transmittance (typically above 90% even in air including Fresnel losses) below a prescribed wavelength, and a high reflectance (above 99%) for wavelengths starting only 5nm above the transmission cutoff wavelength. In addition, these filters can maintain the high reflectance bandwidth for of up to 150nm.
• Plot line 114 depicts a typical spectrophotometric plot for a blue LED. Only a tiny fraction, 114 ⁇ is outside the transmittance curve 113. Such spectral filtering, however, is angle-sensitive, with wavelength shift 115 showing the effect on the entire filter spectrum of 27° off-normal incidence. This shows that plot 114 would be shifted enough to cause all the blue light to be reflected.
• FIG. 11B is a graph similar to FIG. 11 A, but with a different spectral plot 110B, illustrating the significance of filter transmittance plot 113, now juxtaposed with dotted-line phosphor absorption curve 115 and solid-line phosphor emission curve 116.
• Absorption curve 115 is nearly coincident with blue-LED emission curve 114 of FIG. 11A, and is all on the transmission side of plot 113.
• Emission curve 116 is nearly all on the reflection side of plot 113, which is what causes the return of white ray 11Or of FIG. 10D, ensuring the recycling of inwardly emitted white light from phosphor 106.
• FIG. 11C shows a similar graph to FIGS. 11A and 11 B, but with a different spectral plot 1110, illustrating the spectral action of composite filter 1005 in FIG. 10G.
• a blue-pass filter 1005B of FIG. 10G has a transmission curve 1113 in FIG. 11 C.
• Dotted curve 1115 is the excitation function of the green phosphor
• solid curve 1116 is its emission function.
• a red-pass filter 1005R of FIG. 10G has transmission curve 1117 in FIG. 11 C.
• Red LEDs 1002R of FIG. 10F have spectral distribution 1118 of FIG. 11 C. Both filters reflect the green phosphor emission wavelengths of curve 1116, enabling the recycling within the large CPC of the phosphor back-emission.
• a filter for this application can be produced using a PYREX wafer as a substrate and depositing on one side of this substrate many thin layers of materials using the well-known vapor deposition process.
• a suitable PYREX wafer is readily available from Corning, Corning NY, with a thickness of approximately 0.3 mm with a dimensional tolerance of ⁇ 0.05 mm. This material has an average index of refraction in the visible range of 1.47. The deposition processes, design procedures and the materials needed to make such a device are well established from prior art.
• a filter can be designed to achieve a minimum transmittance of above 85% for wavelengths 400 to 495nm, while having a reflectance above 98% for wavelengths in the range of about 515nm to 700nm.
• Such a device can be made into large wafer and then the required shapes can be cut into smaller pieces to match the size of filter 105. This approach can appreciably lower the cost of the filter.
• Other even more efficient designs are readily available from industry sources such as the devices available from JDS Uniphase of Santa Rosa, CA, using a variety of well-established processes, materials and design procedures.
• FfG. 12 shows distribution-transforming element 120, with a wide-angle ( ⁇ 90°) port 121 marked by end-points 123 and 124, and spatially wider narrower- angle port 122, marked by end-points 125 and 126.
• Point 127 is a point on the surface of element 120 between end points 123 and 125 from which a ray at the critical angle ⁇ of the transparent medium composing element 120 will just exit from element 120 at end-point 1,26 on the opposite side.
• Point 128 is directly opposite point 127.
• the profile of element 120 is an ellipse with foci at opposite points 124 and 126. Between end-point 125 and point 127 is a parabola with focus at point 124 and axis parallel to the ray running from point 127 to point 126. The opposite side, from end-point 124 to point 128 and from point 128 to end-point 126, is correspondingly shaped. To the left of points 127 and 128 is a CEC (compound elliptical concentrator), while to their right is a CPC.
• the narrower-angle output of distribution-transforming element 120 serves as suitable input for further embodiments.
• the advantage of this device relative to a simple CPC with exit angle 2 ⁇ is that TIR is more easily achieved at the bottom edges 123 and 124.
• Equally important for building blocks of the optical manifolds of the optical transformer described herein are etendue-conserving ways to transport luminance at a high NA, which is typically around 1 , while mixing it to achieve high uniformity and a constant color.
• the NA can be calculated using either of the following equations:
• Inside wall 1353 is a flat mirror for which TIR is operable, running from point F1 on port 1351 to point F2 on port 1352.
• Outside wall 1354 comprises a parabolic arc running from point P1 on port 1351 to point P2, with focus at point F2 and axis making an angle ⁇ to the normal to the entrance aperture 1351 , in the direction (clockwise direction as seen in FIG. 13A) more nearly perpendicular to the line F2-P1 , an elliptical arc running from point P2 to point P3, with foci F1 and F2, and a parabolic arc running from point P3 to point P4 on port 1352 with focus at point F1 and whose axis makes an angle ⁇ to the normal to the exit aperture 1352.
• FIG. 13B depicts a ray trace of corner turner 1310.
• Edge rays 1357 in FIG. 13B make an angle ⁇ to the normal to entrance aperture, which is the complement of critical angle ⁇ c for the material of this device. Only one of them, ray 1357e, is reflected by TIR. All the rest, refractively transmitted rays 1357r, constitute leakage and a partial device- failure. More complete ray traces show that 100% delivery is only obtained when the ray incidence angles are less than or equal to the angle between the line connecting points F1 and P4, and the normal to entrance aperture in FIG.
• FIG. 13C is a cross-sectional view of an angle-rotator 130, with a first port 131 and a second port 132, which are in complete exchange for light of angular width 2 ⁇ . This angle is twice the complement of the critical angle for the transparent material of rotator 130.
• the second port 132 is at angle ⁇ from the plane of port 131 , generally at the convenient value of approximately 45°, enabling two angle rotators to transport luminance around a right-angle bend with substantially no losses, a situation that would cause inescapable losses for the simple round or square cross-sections of the prior art.
• a flat sidewall 133 extends between foci Fi and F 2 of elliptical segment 134, which is in turn flanked by flat sidewalls 135 and 136.
• Sidewall 135 is oriented perpendicular to entrance aperture 131
• sidewall 136 is oriented perpendicular to exit aperture 132.
• Rays 137 run from focus Fi to focus F 2 via a single total internal reflection
• ray 138 runs via a single total internal reflection from the opposite side of port 131 from point F 1 to the opposite side of port 132 from point F 2 .
• This nonimaging optical configuration tends to smear out any luminance non- uniformities it receives. This smearing is because each point on the second port 132 receives light from the entirety of port 131 as well as from reflections from the walls of angle rotator 130. Since an image is just another type of luminance- nonuniforrnity, this is why this and other embodiments herein are termed 'nonimaging 1 .
• FIG. 13D is a cross-sectional view of an angle-rotator 1300 similar to that in FIG. 13C, comprising outer arc 1301 with center of curvature at point C and inner arc 1302 also centered on point C.
• Tailored curves 1303 terminate both ends of arc 1302, as do tailored curves 1304 for arc 1301.
• Curves 1303 and 1304 jointly define end ports 1305 and 1306.
• Their two-way nature is shown by oppositely directed rays 1307 and 1308, totally internally reflecting at outer incidence angle ⁇ and inner angle ⁇ , respectively against arcs 1301 and 1302.
• the end-ports are not shown refracting the rays since they are expected to be joined to other optical manifolds such as disclosed herein.
• FIG. 13E also shows an angle-rotator 1300, but with complete sets 1309 and 1310 of parallel paths of edge-rays, which define the angular limits within which rotator 1300 will convey all luminosity through large arcs via total internal reflection.
• FIG. 14 is a cross-section of an optical shifter 140, comprising first angfe rotator 141 and oppositely oriented second angle rotator 142. To fit together, both rotators have been modified by removal of segments analogous to flat segment 135 of FIG. 13C. Thus interface F 1 -F 3 is wider than the input light.
• the net effect of shifter 140 is, in this example, a lateral shift of 1.5 widths of an input luminance distribution, which of course is confined to the critical angle of the transparent material composing it. The multiple internal reflections within shifter 140 tend to smooth out any luminance non-uniformities entering it.
• FIG. 15A is a cross-section of optical shifter 150, also for lateral luminance shifting with no angle rotation.
• First port 151 spans points F-i' and F2.
• Second port 152 spans points F 1 and F 2 ' and is shifted a half width from port 151 , as shown by dotted line 150L.
• Straight-line segment F-i'Pi is perpendicular to port 152
• straight-line segment F 2 'P 2 is perpendicular to port 151.
• Parabola F1P1 has focus at F2 and axis parallel to ray ⁇ .
• Parabola F 2 P 2 has focus at Fi and axis parallel to ray r 2 , which is parallel to ray r-i.
• element 150 tends to smear out, as previously discussed regarding FIG. 13C, non-uniformities of the luminance distributions entering it.
• FIG. 15B is a cross-section of optical shifter 155, for lateral luminance shifting by its full width, as shown by axis 155L.
• a first port 156 spans from point 15BPT1 at one end of axis 155L to point 15BPT2.
• a second port 157 spans from point 15BPT3 to point 15BPT4 at the other end of axis 155L.
• light is confined to the critical angle 15BA1 of the transparent material composing shifter 155. This is shown in FIG. 15B as the acute angle formed between the line defined by the ray from points 15BPT3 to 15BPT7 and the axis 155L.
• the perimeter of shifter 155 is partly composed of straight lines, from point 15BPT2 to point 15BPT5 and from point 15BPT3 to point 15BPT6, which are perpendicular to the ports 156 and 157.
• Parabolic segment 158 runs from point 15BPT5 to point 15BPT4, and has its focus at point 15BPT1 and its axis parallel to the ray defined by points 15BPT7 and 15BPT3.
• Parabolic segment 159 runs from point 15BPT6 to point 15BPT1 , and has its focus at point 15BPT4 and its axis also parallel to the ray defined by points 15BPT7 and 15BPT3.
• FIG. 15C is a cross-section of the same optical shifter 155 shown in Fig. 15B.
• the right hand side (segments 15BPT1-15BPT2-15BPT4) of the device relative to the left hand side (segments 15BPT1-15BPT3-15BPT4) in such a way that point 15BPT1 is always on the left parabola 159 and first port 156 is moved to the position 15BPT1M 5BPT2*, the lateral shifting of the light can be changed to any value while maintaining its angular aperture.
• FIG. 15A and 15B show two variations along a continuum of possible values of lateral shift of luminance. Greater shifts merely require a longer shifter than 155 Of FIG. 15B.
• FIG. 16 is a perspective view of an optical twister 160 that has a first rectangular port 161 and a second port 162 oriented perpendicularly to it.
• a spiral curve 163 is one of four forming the corners of 160.
• Lambertian LED 165 positioned across air gap 16Og, so that light inside device 160 is confined to the critical angle of its material, with little loss being conveyed from face 161 to 162.
• FIG. 17 is a cross-sectional view of an optical manifold 170 that incorporates angle rotators. Particularly, FIG. 17 shows how angle rotators can be combined to make an optical manifold 170. LEDs 171 and 172 shine their light across respective air gaps 171g and 172g, into respective angle rotators 173 and 174, the latter positioned in accordance with the length of straight section 175. The entire width of exit port 176 receives light from both LEDs.
• FIG. 18 is a perspective view of an embodiment of the optical manifold 170 incorporated into a three-dimensional design. Lambertian LEDs 181 and 182 shine into manifold 180 and their combined light issues from an exit port 183.
• FIG. 19 is a perspective view of an optical manifold 190 that has a square input port 191. Sequential angle rotators 192 and 193 feed rectangular output port 194. Straight rectangular section 195 feeds sequential angle rotators 196 and 197, thence rectangular output port 198. The length of section 195 is adapted to put ports 198 in the same plane as port 194.
• FIG. 2OA is a schematic view of an optical manifold 200, comprising a lateral shifter 201 receiving light from a red LED R, a mixing rod 202 receiving light from a green LED G, and a lateral shifter 203 receiving light from a blue LED B.
• a duct 204 receives their mixed light.
• all light is confined within a critical angle ⁇ , because as previously the LEDs shine across a small air gap, such as 201 g shown.
• FIG. 2OB is a schematic view of an optical manifold 205, similar to manifold 200 (FIG. 20A) in having an input duct, 206, fed by three branches, 207- 209. Manifold 205, however, is larger in order to reach more separated sources.
• Input branches 207 and 208 are each similar to the shifter shown in Fig. 14.
• Upper branch 207 is shown as comprised of upward-curving first angle-rotator 207a and downward-curving subsequent angle-rotator 207b, with imaginary line 207d joining them.
• Upper branch 207 is for red LED R and lower branch 208 is for blue LED B 1 while a longer mixing rod, 209, is for green LED G.
• 21 is a cross-section of a 4:1 optical manifold 210, with coplanar input ports 211 , angle rotators 212, and output port 213, receiving the light from the input ports.
• Slit-like cracks 214 where angle rotators 212 merge into a combiner of optical manifold 210 would in actual practice be slightly filleted, defined as the replacement of the tip of such a long crack with a wider rounded tip, perhaps a few thousandths of an inch wide.
• FIG. 22 depicts a 4:1 optical manifold 220, with coplanar LEDs 221 , dual angle-rotators 222, and an exit port 223.
• the coplanar LEDs 221 are spaced farther apart than those of FIG. 21.
• FIG. 23 shows a 4:1 optical manifold 230, with coplanar LEDs 231 immersed in angle transformers 232, identical to that of FIG. 12. The light from them proceeds down angle rotators 233 to exit port 234.
• the distance between the input ports can be adjusted to any desired distance, while allowing the ports to reside on a common plane. This capability is particularly useful when designing a particular manifold combiner for a plurality of LEDs that reside on a common circuit board, as the distance between the LEDs required for good thermal management can be easily accommodated.
• FIG. 24 depicts arcuate 4:1 optical manifold 240, with input ports 241 , angle rotators 242, and exit port 243.
• Outer walls 244, 245, and 246 and inner wall 247 are circular arcs concentric on point C. Radius R must be sufficiently large to prevent leakage out these arcuate walls.
• the sharp creases of this device can be modified by either chamfering or filleting the creases, or a combination of both, without having any appreciable effect on the transfer efficiency or output uniformity.
• 25 is a schematic view of an arcuate 4:1 optical manifold 250, comprising four input ports 251 , each with small angle rotator 252, and a common output port 253.
• a small angle rotator 254, a medium size angle-rotator 255, and a large angle-rotator 256 enable the manifold 250 to have a radius of curvature varying from a small radius 257 through medium radius 258 to a large radius of curvature 259.
• These radii, and the inter-branch spacings, are controlled by the rotation angles and relative sizes of the various angle rotators comprising the particular manifold.
• FIG. 26A is a perspective view of a 2x2:1 optical manifold 260 with non-coplanar square input ports 261 , each with small angle rotator 262. Each pair of rotators 262 feeds a rectangular distribution to large angle-rotators 263. In FIG. 26A, each of the four ports 261 has been placed in arbitrarily different planes, but could as easily be in the same plane.
• FIG. 26B is a perspective view of the 2x2:1 optical manifold 260 of FIG. 26A, also showing a square exit port 264 fed by the rectangular angle- rotators 263, which in turn are fed by the angle-rotators 262 acting in the plane orthogonal to that of the rotators 263.
• FIG. 26C is a perspective view of a 4:1 manifold 2650, including an output port 2651 fed by two angle rotators 2652, each fed by a pair of angle rotators 2653 in the orthogonal plane. Each of these four rotators leads through two more rotators to form one of four legs 2655.
• FIG. 26D is a perspective view of a 9:1 manifold 2660 with the same corner legs 2665 as 2655 of FIG. 26C 1 but having a larger output port 2661. Between the corner legs 2665 are central legs 2666 and side legs 2667, which comprise an upper angle rotator 2667A and a lower angle rotator 2667B, connected by light pipe 2667P. A central light pipe 2668 is at the very middle of this 3x3 array of optical ducts.
• FIG. 27A is a perspective view of a more elaborate 4x4:1 optical manifold 270 that has sixteen coplanar input ports 271 , each with a dual angle rotator 272. Each column of four dual angle-rotators feeds a large dual angle- rotator 273.
• FIG. 27B is a perspective view of the 4x4:1 optical manifold 270 of FIG. 27A from another view, showing a square output port 274.
• FIG. 28A is a perspective view of a 4x4:1 optical manifold 280, comprising sixteen coplanar input ports 281 , each having a dual angle-rotator 282 feeding second angle rotator 283, which is in a plane turned at 90° to the plane of dual angle-rotator 282. Columns of four of these dual angle rotators feed into four twisters 284, followed by large angle rotators 285.
• FIG. 28B is a perspective view of a manifold 280 as in FIG. 28A viewed from another angle, showing a square exit port 286.
• FIG. 29 is a perspective view of an optical manifold 290, similar to what might be utilized to illuminate the instruments of an automotive dashboard.
• dual input LEDS 291 feed into the manifold 290, with the possibility of one operating as primary illuminator and the second as backup or daytime illuminator. Alternatively, the two LEDs could have different colors to signal different overall conditions.
• Another advantage of various of the optical manifolds described herein is their ability to alter not only the limiting angle of light entering the manifold, but also the spatial shape of the luminance entering it, particularly from square to rectangular.
• the luminance shifters of FIGS. 15A and 15B can be adapted for this purpose, enabling elongated luminance distributions to be produced.
• FIG. 30 is a perspective view of a luminance shifter 300, formed from profile 301 of width w (at port 302), by an orthogonal sweep by w/2, so that first port 302 is a 2:1 rectangle. Second port 303 is shifted by w/2 as shown in FIG.
• FIG. 31 A is an exploded, perspective view of another embodiment.
• Upper half-width shifter 300U is contiguous across line 300Ud with orthogonal shifter 305U, with downward shift of w/4.
• Nearly identical but inverted lower shifter 300L is contiguous with shifter 305L, to provide a side shift of w/2 and an upward shift w/4.
• FIG. 31 B is a perspective view of the monolithic etendue-squeezer 310 shown in exploded view in FIG. 31 A.
• a square input face 311 is split into a top duct 311 U and a lower duct 311L, also diverging to form a 4:1 rectangular output face (not shown).
• this device operates on light within the critical angle of its transparent material.
• FIG. 31 C is another perspective view of the etendue-squeezer 310 shown in FIG. 31 B, showing a 4:1 rectangular output face 312, and also showing its width 2w and height w/2.
• FIG. 32 is a perspective view of a monolithic 9:1 etendue-squeezer
• a practical issue with many embodiments of the optical manifold described herein is where to put attachment points for mounting a manifold in its proper position. When a surface is optically active, placing a mounting fixture thereupon will result in optical losses through diversion of light from its intended destination. Accordingly, it is often desirable to arrange for some optically inactive surfaces to be part of a manifold.
• FIG. 33A is a cross-sectional view of a light duct 330 having an input port 33A1 and an output port 33A2, with limiting incidence angle ⁇ upon both.
• Side of duct 330 comprises parabolic arc 33AP1 with focus at point 33APT12 and axis parallel to light ray 33AR1 and extends from point 33APT1 to point 33APT2.
• Point 33APT2 is on the straight line that goes through point 33APT15 and in the direction defined by the angle ⁇ relative to the normal to the entrance aperture 33A1.
• the side wall continues with elliptical arc 33AE1 with foci 33APT15 and 33APT12, which extends from point 33APT2 to point 33APT3.
• Parabolic arc 33AP2 extends from point 33APT3 to point 33APT5 and has focus at point 33APT12 and axis parallel to ray 33AR2.
• Elliptical arc 33AE2 has foci 33APT13 and 33APT12 and extends from point 33APT5 and 33APT6.
• Elliptical arc 33AE3 has foci 33APT13 and 33APT16 and extends from point 33APT6 to point 33APT8.
• Flat mirror 33AFM1 completes the left side of the light guide and extends from point 33APT8 to point 33APT9.
• Point 33APT8 is obtained by intersecting a straight line perpendicular to the exit port 33A2 passing through point 33APT9 and another straight line passing through point 33APT10 and that makes an angle ⁇ to the normal to the exit port 33A2.
• Point 33APT16 is on the straight line connecting points 33APT8 and 33APT10.
• the light guide starts with a parabolic arc 33AP3 with focus 33APT16 and axis parallel to ray 33AR4 and extends from point 33APT10 and 33APT12.
• the profile continues with non-optically active curve 33A3 that may be given any shape, as long as it does not intersect the straight line connecting points 33APT12 and 33APT13.
• Parabolic arc 33AP4 with focus at point 33APT1 and axis parallel to ray 33AR3 exrtends from point 33APT13 to point 33APT14.
• Flat mirror 33AFM2 completes the design and extends from point 33APT14 to point 33APT15.
• 33B is a cross-sectional view of an angle-rotating luminance duct 3300, resembling that of FIG. 13D, with a full 90° light rotation denoted by angle 33B1.
• the acceptance and exit angles 33B4 are both the same value.
• MP stands for macrofocal parabola (as defined in the paper "Macrofocal Conies as Reflector Contours", D. Spencer, Journal of the Optical Society of America, Vol. 55, No.1 , pp. 5-11 , January 1965) and C for circle.
• the side wall starts with macrofocal parabola 33BMP1 which extends from point 33BPT1 to point 33BPT2.
• the light guide continues with circular mirror 33BC1 with center 33BPT8 and extending from point 33BPT2 to point 33BPT7.
• the inner wall is composed of flat mirror 33BFM1 extending from point 33BPT5 to point 33BPT4. This mirror is perpendicular to the exit aperture.
• Macrofocal parabola 33BMP2 extends from point 33BPT4 to point 33BPT3 and reflects rays parallel to ray 33BR1 as if they were tangent to the circle 33B3, which is an extension of the caustic 33B2.
• this mirror is exemplified by ray 33BR1 which after reflection appears to come from a tangent point 33BPT6 to circle 33B3.
• the profile is completed by the non-optically active surface 33B6 that may be given any shape, as long as it does not intersect the circular caustic 33B2 with center 33BPT8 and going from point 33BPT3 and 33BPT9.
• the optic is symmetrical relative to vertical line 33B5. Since mirror 33BC1 is a circular mirror and 33B2 is a circular caustic, both with the same center, the rotation that the optic provides can be easily changed by changing the angle 33B1 (with the corresponding decrease in arc length for 33BC1 and 33B2 and rotation of the side mirrors) while keeping the rest of the geometry unchanged.
• FIG. 34 is a cross-sectional view of a light duct 340, which has symmetrically placed ports 341 and 342.
• Its lower contour comprises on the left, parabolic mirror 34P1 extending from point 34PT1 and 34PT2 and having focus 34PT3 and its axis parallel to 34R1.
• the upper contour comprises on the left flat mirror segment 34FM 1 perpendicular to port 341 running from point 34PT6 to point 34PT5. It then continues with parabolic mirror 34P2 from point 34PT5 to point 34PT4, which has focus 34PT1 and its axis parallel to ray 34R1.
• the profile is competed by non-optically active curve 343 that may be given any shape, as long as it does not intersect straight line connecting points 34PT4 and 34PT3.
• the acceptance angle equals the exit angle and is defined by the angle between ray 34R1 and the line connecting points 34PT1 and 34PT5.
• the design is symmetrical relative to the vertical line 344.
• FIG. 35 is a cross-sectional view of a light duct 350 that has plurality of input ports 351 and an exit port 352.
• Input ports 351 are perpendicular to flat mirrors 35FM3 and 35FM 1.
• the acceptance angle of the device is defined by the angle between the line from point 35PT2 to point 35PT12 and ray 35R1. Both make the same angle to the flat mirrors 35FM3 and 35FM1.
• the exit angle is defined by the angle between the line connecting points 35PT8 and 35PT10 and the line that contains points 35PT9 and 35PT7.
• Flat mirror 35FM1 extends from point 35PT1 to point 35PT2.
• the light guide profile continues with parabolic arc 35P1 extending from point 35PT2 to point 35PT3 and having its focus at 35PT11 and its axis parallel to ray 35R1.
• Elliptical arc 35E1 extends from point 35PT3 to 35PT4 and has foci 35PT12 and 35PT11.
• Parabolic arc 35P2 extends from point 35PT4 to point 35PT6 and has its focus at 35PT12 and its axis parallel to ray 35R2.
• Elliptical arc 35E2 extends between points 35PT6 and 35PT7 and has its foci at 35PT12 and 35PT9.
• Parabola 35P3 extends from point 35PT7 to point 35PT8 and its focus at 35PT12 and its axis parallel to the ray from point 35PT7 to point 35PT9.
• the light guide profile starts with flat mirror 35FM2 extending from point 35PT9 to point 35PT10.
• Parabolic arc 35P4 extends from point 35PT10 to point 35PT11 and has its focus at point 35PT8 and its axis parallel to ray 35R2.
• the design is completed by non-optically active surface 353 extending from point 35PT11 to point 35PT12 that may be given any shape, as long as it does not intersect straight line connecting points 35PT11 and 35PT12. [0318] FIG.
• 36 is a cross-sectional view of a luminance duct 360, having a configuration that is bilaterally symmetrical about dotted line from point 36PT1 to point 36PT2, and having ports 363. Both optics 361 and 362 are identical to optic 350 where the flat mirrors 35FM1 and 35FM3 and ports 351 were removed. Line from points 36PT1 to 36PT2 in FIG. 36 is the same as line from points 35PT2 to 35PT12 in FIG. 35.
• FIG. 37A is a cross-sectional view of an extended optical manifold comprising system 350 of FIG. 35, and a four-part manifold 371 fed by four LEDs 372.
• the optical manifold 371 comprises the four sections 360 of FIG. 36, as well as angle rotators 374 and angle transformer 375, which are shown joining to duct 350 by arrows 376.
• Optically inactive surfaces 373 are available for mounting as well as for the location of injection gates and ejector pins in injection molding.
• FIG. 37B is a perspective view of another embodiment of an optical manifold.
• the optical manifold 3700 in FIG. 37B combines elements of previous Figures. In FIG.
• an optical manifold 3700 comprises four input ports 3701 (each with CPC 3703) and a single output 3702 having only their combined etendue, so that all light entering the input ports will be conveyed out the exit port.
• Each input port 3701 feeds one of the angle-rotators 3704, identical in profile to the embodiment of FIG. 33A.
• the rotators feed combiner 3705, which is identical to that of FIG. 22,- and which in turn connects with large rotator 3706.
• a structural beam 3707 connects with the optically inactive flanges of rotators 3704, providing secure mounting in a different plane than that of flange 3708.
• FIG. 37C is a cross-sectional view of yet a further combination, showing two individual dual-lens LEDs with remote phosphors 3750, identical to that of FIG. 7E, including blue-pass dichroic filters 3755, seen to be recycling rays 3756 of phosphor back emission.
• Each phosphor feeds angle rotator 3770, their luminosity combined at output port 3780.
• Brackets 3775 provide sturdy support so that phosphors 3760 receive no structural loads.
• FIG. 38A is a cross-sectional view of a dielectric CPC with source S1 , emitting edge rays 383 illuminating dielectric CPC 382 with receiver R1. Nonuniformities across S1 will be smoothed out to give a uniform distribution at R1.
• the curved front faces enable this embodiment to be shorter than flat-faced CPCs.
• FIG. 38B is a cross-sectional view of a dielectric CPC in alternative configuration. Because free-space propagation of edge-rays can be intolerant to position errors, FIG. 38B shows an alternate configuration that ensures light delivery.
• Flat-faced dielectric CPC 385 with source S2 illuminates dielectric block 387, which in turn illuminates CPC 386 with receiver R2.
• air gap 388 is required for some embodiments.
• Anti- reflective coatings can be applied to the faces of block 387 proximate to the air- gap to minimize the losses due to Fresnel reflections.
• FIGS. 39A and 39B are cross-sectional views of an alternative arrangement that includes two CPCs.
• FIG. 39A shows how a prism coupler may be useful for transferring flux.
• CPC 39A3 a collects the light from source 39A1 and collimates it onto diagonal mirror 39A5 which reflects it towards CPC 39A4 which then concentrates it onto receiver 39A2.
• This geometry is not perfect and some of the rays 39AR3 that leave the source will escape through the side walls of the optic, as for example is the case for rays 39AR 1 and 39AR2.
• the optic of FIG. 39B is similar but is an improvement of the embodiment of FIG. 39A.
• CPC 39B3 collects the light from a source 39B1 and collimates through air gap 39B6.
• Diagonal mirror 39B5 reflects this light through air gap 39B7 and into CPC 39B4, which in turn concentrates the light onto the receiver 39B2.
• the paths of the light rays inside the optic are exemplified by light rays 39BR1.
• Air gap 39B7 is in the direction of the flow lines of the radiation coming out of CPC 39B3 and air gap 39B6 is in the direction of the flow lines of the light reflected by mirror 39B5 and also those of CPC 39B4.
• This arrangement allows a perfect geometrical transfer of light from source 39B1 to receiver 39B2. can be achieved There will be some optical losses due to Fresnel losses at the air gaps and, therefore, anti-reflective coating may be employed to reduce them to a negligible level.
• FIG. 40 is a cross-sectional view of an alternative configuration of an optical manifold.
• the method shown and discussed with reference to FIG. 10D of recycling phosphor back-emission utilizes a blue-pass filter that returns this back- emission to the phosphor. This method utilizes low absorption in the phosphor.
• the configuration of FIG. 40 can be utilized for a phosphor that does have significant absorption of its own emission wavelengths.
• Dielectric CPC 401 has blue LED 402 coupled to it, with its directed output shown as edge rays 403. ⁇ This blue light passes unimpeded through diagonal blue-pass filter 404 and proceeds into dielectric CPC 405 to illuminate phosphor patch 406.
• FIG. 41 is a cross-sectional view of an alternative configuration of an optical manifold.
• FIG. 41 shows a similar configuration to FIG. 40, including a dielectric CPC 411 having a blue LED 412 coupled thereto.
• the CPC 411 has a diagonal exit face 413 with a blue-pass filter coated thereupon.
• Optically joined to face 413 is a diagonal prism 414.
• a dielectric CPC 415 Adjacent to the prism 414 is a dielectric CPC 415, having a phosphor patch 416 on its exit face. Phosphor back-emission proceeds through prism 414, reflects off diagonal exit face 413 into dielectric CPC 417. This reflected back-emission forms a virtual source 418 at the exit face of CPC 417.
• An expanded view shows how flat section 417f acts to restrict incidence angles on face 418 to the critical angle ⁇ c .
• FIG. 42 is a cross-sectional view of an alternative configuration of an optical manifold.
• FIG. 42 depicts a similar configuration to FIG. 41.
• a dielectric CPC 421 is coupled to the blue LED 422 and has a diagonal exit face 423 with a blue-pass mirror coated thereupon and optically joined to prism 424.
• Dielectric CPC 425 receives the blue light from LED 422 and concentrates it on phosphor 426. The phosphor back-emission is reflected through prism 424 into diagonal prism 427.
• Third dielectric CPC 428 receives the back emission from prism 427 and concentrates it through the exit face 429.
• FIG. 43 is a cross-sectional view of a free-space version of FIG. 42.
• Curved-top dielectric CPC 431 is coupled to the blue LED 432 and sends its light through blue-pass filter 433 to the second dielectric CPC 434, having a phosphor patch 435 at its exit face.
• the phosphor back-emission is reflected by a filter 433 to the mirror 436, thence into the third CPC 437, where it is concentrated through the exit face 438.
• FIG. 44 is a cross-sectional view of an alternative configuration of an optical manifold that resembles FIG. 43.
• FIG. 44 has a CPC 441 , a blue LED 442, a blue-pass filter 443, a second CPC 444, a phosphor patch 445, a diagonal mirror 446, and a third CPC 447.
• a Y-shaped combiner 448 has an output face 449 with twice the area of the phosphor patch 445.
• FIG. 45 is a cross-sectional view of an optical manifold that can be used to combine a plurality of LEDS of different colors to provide a multiwavelength light output.
• the output area is about the same as the input area of any one color, rather than their sum, since this would increase luminance, for example by a factor of about three.
• the size of the output area must be larger than the input area by a factor equal to the square of the index of refraction of the dielectric material.
• CPC 45 shows one way of accomplishing this.
• Three curved-face dielectric CPCs are shown, including a red CPC 451, a green CPC 452, and a blue CPC 453.
• Corresponding LED sources, R, G, and B are in optical contact with their respective CPCs, i.e., with no air gap.
• a diagonal filter 454 reflects only red light.
• Second diagonal filter 453' reflects only blue light. All three colors are thereby overlaid and sent into fourth CPC 455, which combines their light into a white resultant at exit face 456.
• the exit face 456 is actually larger than faces R, G, or B, by a factor at least equal to refractive index n of the dielectric material comprising the four CPCs 451 , 452, 453, and 455.
• the geometry of its tip is similar to the one shown in close-up 407f in FIG. 40. Refracted rays exiting face 456 will range up to 90°.
• FIG. 46 is a cross-sectional view of an alternative configuration of an optical manifold that can be used to combine a plurality of different color LEDS to provide a multiwavelength light output.
• FIG. 46 shows a red dielectric CPC 461 , a green CPC 462, and a blue CPC 463.
• a first diagonal filter 464 reflects only red light, and a second diagonal filter 464 reflects only blue light.
• a prism block 466 is assembled from four smaller prisms having these filter coatings upon them.
• a fourth dielectric CPC 467 receives three superimposed radiant inputs and combines them into a single white output at exit face 468, whose edge is n times the size of one of edges of the three colored CPCs.
• a straight section 467f restricts incident rays to critical angle ⁇ c .
• FIG. 47 is a cross-sectional view of an alternative configuration of an optical manifold that resembles FIG. 46.
• the fourth CPC can be dispensed with.
• an air gap is not strictly necessary between the prism block and the green CPC.
• FIG. 47 shows the result, with red dielectric CPC 471 and blue dielectric CPC 473 as before, but green CPC 472 has a dual-diagonal exit face. Red reflector 474 and blue reflector 475 are applied to the faces of diagonal sub-prisms 476, 477, and 478.
• the combined white output 479 has beamwidth ⁇ that is the Snellian resultant of internal angle ⁇ of the three CPCs.
• FIG. 48 is a cross-sectional view of an alternative configuration of an optical manifold that can be used to combine a plurality of different color LEDs to provide a multiwavelength light output. It would in some cases be more convenient if the LEDs could be in the same plane. Accordingly, FIG. 48 shows a plurality of parallel dielectric CPCs, including a red CPC 481 , a green CPC 482, and a blue CPC 483. First and second diagonal mirror-prisms 484 and 485 are also shown. Sub-prisms 486, 487, and 488 are as before, providing a white output 489.
• FIG. 49 is a cross-sectional view of an alternative configuration of an optical manifold that can be used to combine a plurality of different color LEDs to provide a multiwavelength light output.
• a free-space version of coplanar sources is also possible.
• FIG. 49 shows a red CPC 491 with mixing rod 491m, green curved-top CPC 492, and blue CPC 493 with configuration identical to CPC 491.
• Side CPCs 491 and 493 are designed to accept radiation confined to the critical angle defined by the direction of light coming out of the LEDs and refracted into the dielectric material of these CPCs.
• the upper tips of mixing rods 491 m and 493m require small CPCs to transform the Lambertian radiation of the LEDs so that it is confined to the critical angle of the mixing rods and the therefore the radiation can be transported down the mixing rods without side losses.
• side CPCs 491 and 493 are designed to accept the light confined to the critical angle
• middle CPC 492 is designed to accept the fully Lambertian radiation emitted by the central LED.
• a diagonal mirror 494 deflects red light onto red reflector 496, while mirror 495 deflects blue light onto blue reflector 497.
• Fourth CPC 498 combines these beams into a white output at exit face 499, with flat section 498f restricting incidence angles at 499 to critical angle ⁇ c .
• FIG. 50 is a cross-sectional view of an alternative configuration of an optical manifold that can be used to combine a plurality of different color LEDs to provide a multiwavelength light output.
• an optical manifold has a red CPC 501 with a diagonal exit face, a green CPC 502, and a blue CPC 503.
• Prism 504 has a red-pass green reflector on its diagonal face.
• Transition prism 505 receives the combined red and green light, and is optically joined to prism 506, which has a blue reflector on its diagonal and white output 507 exiting it.
• FIG. 51A is a cross-sectional view of an alternative configuration of an optical manifold that utilizes coplanar sources. The embodiment of FIG.
• 51 A includes a red dielectric CPC 511, a green dielectric CPC 512, and a blue dielectric CPC 513.
• a diagonal mirror prism 514 reflects red light downwards through transition prism 515.
• Optically coupled to prism 515 is diagonal prism 516 with a green reflector coating on its diagonal, which sends green light down through transition prism 517.
• Optically coupled to prism 517 is diagonal prism 518 with a blue reflector coating on its diagonal.
• White output 519 exits the bottom of prism 519 with beamwidth ⁇ . The distance between the LEDs can be easily changed by independently extending light guides 515 and/or 517. [0337] Reference is now made to FIG. 51 B.
• a green phosphor with good quantum efficiency could produce about the same luminosity as a green LED of the same radiant output as its blue-excitation LED, but its broader range of wavelengths is better for color rendition.
• the second phosphor could be a conventional yellow phosphor much like that now used in white LEDs, but doped to reduce the red portion of its emission. This is advantageous in that red wavelengths have a large Stokes loss when generated by photoluminescence. Instead, a red LED can be mixed with the two phosphors to produce an excellent white source.
• 51 B is a cross-sectional view of a configuration of an optical manifold that generates a multiwavelength light output.
• the optical system in FIG. 51 B includes LED manifold 5100 that produces white light, and including two blue LEDs 5101 and a red LED 5102 as luminous inputs.
• the blue LEDs 5101 feed CPCs 5103, which collimate their light onto blue-pass dichroic filter 5104, which in turn lies atop CPCs 5105.
• Green phosphor 5106 and yellow phosphor 5107 have their back-emission recycled by filter 5104, and their enhanced forward emission collected by small CPCs 5108, which in turn feed angle-rotator pairs 5109.
• FIG. 51 C is a cross-sectional view of an alternative configuration of an optical manifold that generates a multiwavelength light output.
• the embodiment of FIG. 51 C has a green phosphor only.
• the optical system in FIG. 51 C includes a manifold 5150 that has an input blue LED 5151 feeding a CPC 5152, which contacts a blue-pass filter 5153.
• a CPC 5154 has a green phosphor 5155 at its small end.
• a phosphor 5155 feeds a CPC 5156, which collimates the phosphor's light onto diagonal red-reflecting filter 5157.
• a blue LED 5158 feeds a CPC 5159, which sends collimated blue light through the filter 5157.
• the red LED 5150 feeds a CPC 5161 , which sends collimated light onto filter 5157, which in turn reflects this light 90° along large CPC 5162.
• a large angle transformer 5162 mixes the light from small CPCs 5156, 5159, and 5161 , and narrows their angle for refraction out of exit face 5164.
• optical transformer described herein to integrate plurality of LED sources enables more than three wavelengths to be used and combined. Because the chromatic aberrations of the human eye tend to disturbingly separate the red and blue images of RGB video, amber and cyan colors can be added to reduce such effects. For example, the stacked configuration of FIG. 51A can be augmented with two more CPCs and fitters for the amber and cyan sources.
• FIG. 52 is a cross-sectional view of an alternative configuration of an optical manifold.
• the embodiment of FIG. 52 includes luminance shifter 520. As shown, light is restricted to angle ⁇ from axis 520a drawn on exit port 521.
• Input port 522 has a smaller width and is laterally shifted with respect to port 521. The reason for the difference in size between the input and output ports is that input port 522 accepts fully Lambertian light from the LED, while output port 521 emits a light that is confined to angle ⁇ .
• the left profile comprises flat mirror 523 extending from point F4 to point P1 , parabolic arc 524 extending between points P1 and P2, with focus at F3 and axis parallel to lines r1 , and elliptical arc 525, extending from point P2 to focus F1, with foci at F2 and F3.
• the right profile comprises parabolic arc 526 extending from point F2 to point F3 and with a focus at F1 and its axis parallel to lines r1.
• FIG. 53A is a plan view of a triplex optical manifold 530 comprising left luminance shifter 531 of FIG. 52 (imaged to the left), middle luminance duct 532, and right luminance shifter 533 of FIG.
• the two shifters mesh with a middle duct 532 along the length of the straight sections of these two shifters (523 of FIG. 52).
• the middle duct has a CPC profile 532c at its entry port that is about 3.12mm tall and which collimates the light to angle 534. This angle matches that of the side light shifters, as indicated in FIG. 52 by angle ⁇ .
• the light exiting CPC 532c is then transported up by light pipe 532f. This results in this example, in an optical system with combined exit surface 53Oe with a width of about 7.2mm.
• FIG. 53B is a side view of the triplex optical manifold 530 shown in FIG. 53A, with a width which is about 2.33mm in this embodiment. All three manifolds in FIG. 53A have a CPC profile 530c in the orthogonal direction to the profile of FIG. 53A. The height of this CPC profile is about 2.28mm and has an exit angle 536. The entry section of middle duct 532f therefore utilizes a dielectric cross-CPC to adjust the vertical and horizontal exit angles to the desired specifications.
• the output angles for the three-fold manifold in the vertical and horizontal directions can be set independently of each other.
• FIG. 54A is a graph that shows the contour diagram 540 of the far-field intensity emitted from the manifold of FIGS. 53A and 53B, with a horizontal angular scale 541 running from 50°left (50L) to right (50R) and vertical scale 542 running from 50° up (50U) to down (50D).
• Contour lines 540c show intensity levels up to a maximum of 3.25 Watts per steradian.
• the contour line has sharp horizontal boundaries at about ⁇ 30°.
• the vertical boundaries of the contour line are less steep, extending to about ⁇ 40°.
• FIG. 54B is a graph 545 that shows the horizontal intensity profile as solfd line 546 and the vertical intensity profile as dashed line 547 emitted from the manifold of FIGS. 53A and 53B. Both profiles have well-defined borders and steep skirts. Their overall form is quite reproducible despite individual differences in the LEDs feeding the manifold.
• FIG. 55 is a graphical depiction that shows a spatial luminance map 550, scaled in millimeters, of output face 53Oe of the manifold of the embodiment shown in FIGS. 53A and 53B.
• the LEDs 531 i, 532i and 533i of FIG. 53A were modeled with central dark zones, a strong form of input nonuniformity. Nonetheless, map 550 has outstanding uniformity compared to the LEDs feeding the manifold, with sharp well-defined edges. This distribution is little affected by the usual positional tolerances of the LEDs, or their individual differences in luminance. Its uniformity and definition are also superior to other high-luminance light sources such as incandescent filaments or arcs. Contours are labeled for 15,000 W/m 2 at the very edge, to over 60,000 at the center. This high power density comes from a single radiant Watt of input.
• FIGS. 56A, 56B, and 56C illustrate an alternative configuration of a triplex optical manifold.
• FIG. 56A is a perspective view of a triplex optical manifold 560, along with three input LEDs 561 , 562, and 563, all on circuit board 564.
• FIG. 56B is a perspective view of a triplex optical manifold 560 as in Fig. 56A, also showing a bulbous free-form lens 565 that shapes the luminous output of manifold 560.
• FIG. 56C is a perspective view of the optical manifold 560 as in Fig. 56A, also showing curved rectangular mirror 566, acting to form collimated beam 568 from luminous output 567 of lens 565. Beam 568 fulfills an automotive lighting prescription for a headlamp or other requirements.
• FIG. 57 is a perspective view of a bank of four luminaires 570.
• FIGS. 58A and 58B illustrate another approach to producing an asymmetrical beam pattern for such applications as automotive lighting, in particular automotive headlamps.
• FIG. 58A shows an out-side perspective view of asymmetric manifold 580 with the shape of triplex manifold 530 of FIG.
• FIG. 53A also comprising secondary duct 581 meshed with primary duct 582.
• FIG. 58B is another perspective view.
• Duct 582 has a cross-sectional shape at exit surface 583 whose outer boundary approximately matches the shape of a far field automotive headlamp beam illuminance or intensity pattern.
• Duct 582 can be tapered in one or more directions along its length to adjust the intensity at various points on exit surface 583.
• the angular output of 580 in the vertical and horizontal directions can also be adjusted by the design of triplex manifold 580m.
• the output from exit surface 583 can then be further adjusted by secondary optics that employ either imaging or nonimaging principles.
• both the small dielectric cross-CPCs 101 , and the large dielectric cross-CPC 103 are two-way sweeps of a basic CPC profile, such as those shown in FIGs 1A 1 2B, and 2C.
• FIG. 59 depicts the geometry of a cross-CPC as the solid intersection 590 of two troughs, namely mutually perpendicular linear-sweep CPCs 591 and 592, of identical planar cross- sections 593. Because each trough has the constant cross-section 593, any light emitted from aperture 594 will be depart trough 592 within its acceptance angle, given that the trough is even longer than shown in FIG. 59. The point to be made is that in spite of the troughs being optically ideal, their intersection 590 is not. In the case of such a shallow cross-section as 593, the departure from perfection is small, but a deeper configuration is another matter.
• FIG. 6OA shows tandem cross-CPC 60, comprised of left-hand cross- CPC 61 and right-hand cross-CPC 62. They are oriented large-end to large-end, joining on face 60m. Light enters at face 60s, also known herein as the entry port, and is received at opposite face 6Or, also known herein as the exit port. Ray tracing simulations show that light entering at 60s is delivered to join-face 60m with nearly 100% geometric efficiency, as expected from common knowledge of CPCs. When such light thereby enters right-hand CPC 62, however, losses become serious. This as a result not previously reported in the literature of nonimaging optics, and motivates several preferred embodiments next discussed herein.
• FIG. 6OB shows the same tandem cross-CPC 60, but filled with light- rays 63, launched rightward from source 60s of FIG. 6OA.
• Prominently visible are the 10% losses from leakage rays 64A, on the right, and the further 5% losses from leakage rays 64B, on the left.
• Leakage rays 64A are lost due to TIR failure of rays that have multiply intersected the walls of right-hand cross-CPC 62 of FIG. 6OA.
• Leakage rays 64B were first retroreflected by right-hand cross-CPC 62, thereby entering left-hand cross-CPC 61 and finally becoming ejected as shown. This 15% loss is unacceptable for a lighting system seeking to improve upon conventional phosphor-conversion LEDs.
• a related inefficiency of the cross-CPC configuration is in the recycling function shown in FIG. 10D. Actual ray-traces, however, show that the efficiency of this process is only 89%. This does not bode well for overall recycling, therefore, because the process depends upon multiple repetitions of the process shown in FIG. 10D, each sapping the recycled light of 11% of its strength.
• These related inefficiencies are endemic to cross-CPCs. They stem from rays that are within the 2D acceptance angle of either CPC trough (as in FIG. 59), but in -3D are outside it. This can be seen in FIG.
• CPCs 61 and 62 show angle- space graph 6100 for the display of ray-direction spots 6101 , representative of light exiting the large end of a cross-CPC.
• the rays can be seen to be confined in direction to within 10° of either axis.
• Circle 6110 also has radius 10°, but numerous rays can be seen to be outside it, in the corners of graph 6100. These rays are the cause of the inefficiencies discussed, in that many of them become lost.
• CPCs 61 and 62 have square cross-section and meet at square flat area 60m.
• the flow lines of CPC 61 at the corners of square flat area 60m are not perpendicular to 60m.
• FIG. 62A schematically displays remote-phosphor system 6200, comprising blue LED 6201 as light source, first CPC 6202, mid-line dichroic filter 6203, second CPC 6204, and remote phosphor patch 6205.
• a phosphor patch is relatively thin, with two surfaces, one receiving light from the CPC, hereinafter called the inside surface, and an opposite side, hereinafter called the outside surface.
• flux diagram 6210 with dotted line 6211 representing LED 6201 , dotted line 6212 representing filter 6203, and dotted line 6213 representing phosphor patch 6205.
• Diagram 6210 utilizes the following mathematical symbols:
• L Luminous flux entering CPC 6202 from blue LED 6201.
• T blue-light transmittance to phosphor patch 6205 from LED 6201 for the optics 6202 and 6204 but not including the losses associated with filter 6203.
• R recirculation factor, the fraction of back-scattered light recycled by CPC 6204 back into phosphor patch 6205.
• the cross-CPC had an 89% value.
• pL integrated reflectance of LED 6201. A value of 70% indicates a higher-quality LED.
• py integrated reflectance of filter 6203 for phosphor emission wavelengths.
• ⁇ b transmittance of filter 6203 for LED blue wavelengths.
• P B fraction scattered back into second CPC 6204.
• P T fraction of the light striking the phosphor patch 6205 that is further transmitted out the front of phosphor. Besides losses to backscattering, this variable encompasses blue-to-yellow conversion losses and Fresnel reflections (including losses , associated if there is cover over phosphor patch 6205).
• b the fraction of non-converted blue light remaining and y is the fraction of converted yellow light
• Q the quantum efficiency of the phosphor
• S ⁇ the fractional phosphor Stokes efficiency.
• Diagram 6210 of FIG. 62A shows initial flux L entering system 6200, which has transmittance T. This does not include the losses in the filter but only the optic elements. Taking also into account the losses for the blue light as it passes through the filter, the flux that intercepts phosphor patch 6205 is at lower flux level of LT ⁇ b . This system transmittance T is 89% for the cross-CPC type. (Below a different preferred embodiment will be presented with 99%.) In its passage through the phosphor, some of the blue light is converted to yellow, but with some energy losses, so that a fraction remains, which is the parameter, x.
• Return arrow LT ⁇ b P ⁇ 6220 shows the flux re-entering CPC 6204, flowing leftward to filter 6203.
• filter 6203 has a transmittance ⁇ b for the blue light
• the blue portion of returning flux after traveling through filter 6203 is LT ⁇ bP ⁇ blb as shown by flux arrow 6222, which will make it to LED 6201 with its flux reduced by the same transmittance T as in its initial pass.
• the fraction PL is reflected by. LED 5201 , and begins its return rightward as flux-arrow LT 2 x b PBl B tbpi_ 6223.
• This blue flux will again be reduced by transmittance T, yielding the returned blue flux-arrow LT ⁇ b P B l B ⁇ b 2 p L. T 2 6225.
• the flux for this pass that transmits through the phosphor is LT ⁇ bPBlB ⁇ b 2 pLT 2 P ⁇ , as is seen in flux-arrow 6227.
• the total light output Lo is then the sum of first pass component, the yellow recycling component and the blue recycling component.
• the expression becomes:
• the remote-phosphor system is asymmetric in the sense that the optic attached to the LED is different from the one attached to the phosphor, there is a differing transmittance of light T L P from blue-chip to the phosphor than the transmitta ⁇ ce T PL from the phosphor to the LED.
• the expression for Lo is:
• This function corresponds to curve 114 of FIG. 11 A.
• PA( ⁇ b ) is the probability of blue light, of wavelength ⁇ b, being absorbed by the phosphor. This function is also known as the excitation spectrum.
• P bF (A b ) is the probability of blue light, of wavelength ⁇ b, entering phosphor patch 6235 and making its way to the front surface F and escaping the layer. This light counts towards the above-mentioned quantity PT-
• PbR(Ab) is the probability of blue light, of wavelength Ab, of escaping out the rear surface R.
• PR(A b ) is the efficiency of recycling blue light of wavelength ⁇ b - The recycled light joins the original flux F(A b ).
• X]Q is the quantum efficiency of the phosphor, the fraction of absorbed blue light that gives rise to emission.
• At/Ay is the ratio of blue to emitted-yellow wavelengths, respectively.
• Fy( ⁇ b ) is the total flux of yellow light generated by the absorbed blue light of wavelength A b .
• PyF(A b ) is the probability of immediate escape out front surface F of the yellow flux generated by blue light of wavelength A b - This probability is wavelength-dependent because the different amounts of absorption of , blue light at its different wavelengths causes a different spatial distribution of yellow emission points, and thus differing probabilities of escape. Strongly absorbed wavelengths cause the emission to be near rear surface R, reducing this probability of escape out front surface F.
• Py R ( ⁇ b ) is the probability of immediate escape out rear surface R of the yellow flux generated by blue light of wavelength ⁇ t > .
• ⁇ b denotes summation over all blue wavelengths to give a total yellow flux out rear surface R.
• p R ( ⁇ y) is the efficiency of the recycling of yellow light. Because of the wavelength-dependent filter in the remote phosphor, this is higher than the recycling efficiency p R ( ⁇ b ) for blue light.
• F( ⁇ y ) is the total flux of all recycled yellow light. Because there is no absorption of yellow light, the following two probabilities are wavelength- independent:
• P F y is the probability of escape out front surface F of yellow light entering rear surface R.
• P Ry is the probability of escape out rear surface R of yellow light entering it. The recycling of this light is not shown, since it is already described in FIG. 62A.
• FIG. 62c shows the results of one such computer simulation.
• Curve 6253 gives the values of extraction efficiency for particular values of P ⁇ , assuming a phosphor scattering coefficient of 100/mm.
• Point A is for a conventional white LED with conformal phosphor and a flat window.
• Point B is for same but with a dome.
• Point C is for a remote phosphor with a flat window, and point D is for same with a dome. This shows the advantage of the remote- phosphor approach of the present invention.
• FIG. 63A and FIG. 63B show a remote-phosphor system comprising blue LEDs 6301 , small rectangular CPCs 6302, and large circularly symmetric CPC 6303.
• Square 6304 is formed by the top ends of small CPCs 6302 and is where a blue-pass filter (not visible) is placed.
• Mirror coating 6306 reflects all light, blue or yellow, back to remote phosphor 6305.
• fillet 6302f forms the common lower surface that connects the outer surfaces of CPCs 6302. Ray tracing simulations by ..the Inventors show that if two of the four CPCs of 6302 have a small fillet (on the order of 0.25 mm radius) between two common surfaces of adjacent CPCs, that performance of the system is unaffected. [0402] In accordance with considerations discussed in FIG.
• circularly symmetric CPC 6303 has acceptance angle 15° so that all light from the small CPCs is accepted. Instead of the 10° circle 6110, a 15° circle would include all directions represented by spots 6101. This results in a 99.5% transmission, rather than the 89% of a square CPC system as in FIG 10A.
• the remote phosphor patch 6306 is circular, however, and is several times larger than the combined area of LEDs 6301. Thus this more efficient configuration has reduced luminance because of the phosphor-patch area is larger than that of the original four LEDs.
• CPC 6303 with an acceptance angle 15° has a theoretical recirculation factor, R, of 97.5% compared to only 85% for the cross- CPC.
• R theoretical recirculation factor
• FIG. 64A is a cross-section, and FIG. 64B a perspective view, of remote phosphor 6400, comprising phosphor patch 6401 , opaque diffuse reflector layer 6402 with square cutout 6402c, and transparent substrate 6403 with beveled edge 6403e matching the slope of large CPC 6303 of FIG 63B.
• cutout 6402c could be any arbitrary shape, including irregular shapes, that is, shapes other than simple convex curves or polygons, such as an alphanumeric character.
• Phosphor patch 6401 has normal thickness (say 50 microns) inside the emitting square 6402c and greater thickness beneath diffuse reflector 6402. This causes most of the blue light thereupon to be converted to yellow light, which is more efficiently recycled than the original blue light. It is also possible, however, to have the layer below the diffuse reflector 6402 be the same thickness as, or thinner than, the phosphor inside the emitting square, since the effective phosphor path length below the diffuser is doubled.
• transparent substrate 6403 has central square ridge 6403r to support the central thickness of phosphor patch 6401.
• Such a configuration is also suitable for a transparent phosphor, from which light extraction would otherwise be difficult because of its higher refractive index (about 1.8 vs. the 1.5 of the CPC).
• a non-uniform phosphor thickness can also be accommodated by other means, however, such as diffuse reflector 6402 having a lip that wraps around the inner boundary of phosphor below the diffuser area. In this approach the downward lip would end on a small outer boundary zone of the emitting phosphor layer, thus allowing, the bottom of transparent substrate 6403 to be made flat.
• This approach also has the advantage that part of the side emission of the thick phosphor layer is reflected back onto itself, possibly improving the uniformity of the externally emitting portion of the phosphor.
• Other approaches are easily conceived of once the fundamental invention is understood by those skilled in the arts relating to this invention. [0407] Besides characters, other irregular or arbitrary shapes such as vehicle lamp-emission patterns could be depicted for imaging into the far field, with an option of non-uniform phosphor thickness for producing spatially variable luminance.
• the blue-pass filter may be placed immediately below the phosphor patch 6401.
• the phosphor patch 6401 is then enclosed in a box of materials reflective to yellow light except for the output port formed by cutout 6402c. Emission of yellow light through the output port 6402c is then extremely high. Blue light that is neither absorbed by the phosphor patch 6401 nor emitted through the output port 6402c is reflected back off the diffuse reflector layer 6402, which may be, for example, titanium dioxide powder with a reflectance of greater than 99%.
• the diffuse reflector layer 6402 which may be, for example, titanium dioxide powder with a reflectance of greater than 99%.
• the reflector layer 6402 covers the thin edge of the phosphor layer 6401 as well as the outside face, so that no gap need be left between the reflector layer 6402 and the blue-pass filter. Because of the sensitivity of the short-pass filter to the angle of incidence, blue light incident on the filter with an angle of incidence greater than about 40° or 45° is reflected back into the phosphor patch 6401. Blue light with an angle of incidence less than, say, 15° is accepted by the CPC 6303, acting as a collimator and returned to the LEDs 6301 , which will reflect about 75% of the light back into the system. Blue light with an angle of incidence between 15° and about 30° is reflected within the optical system and ultimately mostly returned to the phosphor patch 6401.
• FIG. 64A and 64B is an example of the general idea, which is used in various embodiments of the present invention, of a phosphor shape that is cut from a monolithic piece and bonded to a transparent substrate.
• the phosphor patch can be made as a composite material where a phosphor layer is deposited on a suitable transparent substrate, such as a sheet or film in a volume production process.
• a suitable transparent substrate such as a sheet or film in a volume production process.
• Such a composite phosphor can be made up as large sheet and then cut into parts using commercially known methods. The part is then bonded to the end of the recycling optic.
• This type of composite-phosphor approach can be in combination with any of the embodiments described herein or derived therefrom.
• the phosphor layer 6401 could be directly deposited onto the surface of transparent substrate 6403 via means such as ink jet printing or others approaches known to those skilled in this art, such as the electrophoretic deposition process developed and used by PhosphorTech of Lithia Springs, Georgia, USA.
• FIG. 62C which illustrates the benefit of the diffuse cover of FIG. 64A and 64B 1 it would be desirable to have means to create a higher luminance source, by reducing source area without a significant drop in extraction efficiency. This is possible if the reduction in extraction efficiency is less than the reduction in area. This area-reduction results in a reduction of PT, which acts in accordance with curve 6253. For an LED with conformal phosphor source, if the derivative of curve 6253 is less than one, luminance will increase in spite of some lumen loss. For example, looking at the slope of the efficiency curve of the remote phosphor system modeled in FIG. 62C, there are sections of the curve where this applies.
• the remote phosphor embodiment of the present invention has a decided advantage over existing commercially available PC LEDs, with regard to use of the luminance boost described herein.
• the two points A and B in FIG. 62C represent the efficiency as a function of P ⁇ for a high performance PC LED with respectively flat and dome covers. These represent the state of the art in PC LEDs. If one models such LEDs as a function of Py 1 it can be seen their efficiency curve (they fall on the same curve) is very steep at the useful values of Pj- Reducing the emitting area for these LEDs actually reduces the luminance and seriously reduces the extraction efficiency.
• FIG. 65A is a cutaway perspective view of remote phosphor system 6500, comprising blue LED 6501 radiating into first collimator 6502 (shown here as a round CPC), which collimates its light at output top plane 6502t.
• Long-pass dichroic reflector 6503 lies at 45 degree to collimator 6502, reflecting all the short wavelengths of blue light downward into second CPC 6504, also round and with the same 10° acceptance angle.
• Extension cylinder 6509 of FIG. 65A is typical of the actual outer surfaces of such a device, wherein filter 6503 would be sandwiched between separate sliced cylinders of transparent dielectric and solid dielectric triangular prism 6506p, which prevents collimated light from CPC 6502 and 6504 being deflected (via refraction at the surface of filter 6503).
• Solid dielectric triangular prism 6506p also can support reflector 6506.
• Embodiment 6500 can also be configured with open reflectors in which case solid dielectric triangular prism 6506p is no longer required.
• White reflector 6505 of FIG. 65A can also have incorporated into it apparatus for managing the heat generated in the phosphor conversion process.
• Many varieties of such apparatus, which can operate via either passive or active cooling principles, are well known to those skilled in the arts of thermal engineering.
• Thermal advantages over conventional conformal phosphor accrue to the remote phosphor because of its isolation from the heat of the source.
• a further thermal advantage accrues to the source as well, since less yellow phosphor-light is returned into it for partial absorption and consequent heat.
• the phosphor's own heat generation is not added to that of the source. This heat can be exemplified with a one-Watt LED that produces 30OmW of blue light, and thus 70OmW of heat.
• the heat flux of 47mW/mm 2 equals 50 suns, and thus will require extra cooling measures, since free convection in air is far too weak (one-Sun heat removal at 3O 0 C delta temperature) to cool the phosphor patch solely through its own surface area.
• the dielectric optic 6303 could be made of a high operating temperature material, one having higher conductivity and thermal diffusivity than typical plastics used for optical components.
• quartz has a thermal conductivity of 3 WVm 0 K versus 0.18 VWm 0 K for acrylic.
• the thermal diffusivity of glasses is much higher than plastics, with quartz at 10 times greater.
• cover 6402 could be multi-layered with an inner reflective layer made of a high thermal conductivity ceramic material and an outer layer of copper or other high-conductivity material, suitably protected from environment.
• the ceramic and/or copper layers could extend much wider than the aperture, and could even include heat-exchange features such as fins. Active cooling could also be employed, such as forced air blowing by highly reliable miniature fans as found in most personal computers.
• a further advantage of completely enclosing the outside surface of the phosphor patch with diffuse white reflector 6505 lies in the case of transparent phosphors formed using a single crystal with very little scattering.
• the high index (1.8) of this material causes extensive light trapping, making it less useful than a scattering phosphor when light must go through it. But with the diffuse reflector in contact with a transparent phosphor, light trapping is eliminated by the reflector's scattering.
• the dichroic reflector 6503 of FIG. 65A is described by FIG. 66A, showing graph 6600 with horizontal axis 6601 for wavelength in nanometers and vertical axes 6602R on the left, for reflectance and relative intensity, and 6602T on the right for transmittance, which in such non-absorbing filters as these amounts to 1 -reflectance.
• Filter reflectance function 6603, which describes the wavelength characteristics of long-pass filter 6503, comprises a fully reflective portion 6603h, extending to 465 nm. This wavelength is only slightly longer than the 458 nm peak of blue LED spectrum 6604. Cliff portion 6603c of filter function 6603 falls to nearly zero by 475 nm.
• the portion of blue spectrum 6604 lying to the right of 6603c will become part of output beam 6508 of FIG. 65A.
• This light has the highest luminous efficacy of all the blue wavelengths from blue LED 6501 of FIG. 65A. It is not so long, however, as to be poor in color rendering. That is, using only the blue light past 470nm (rather than the 500nm of the filter in FIG. 11 B) keeps both good color gamut in chromaticity and good color rendering.
• the blue light shines through the phosphor patch, about half the unabsorbed blue is very short, nearly violet-looking wavelengths of ten times lower efficacy as compared with blue wavelengths past 470nm.
• using all of some wavelengths for transmission and all the rest for luminescence has superior efficacy over using all blue wavelengths the same, which ignores their huge differences in efficacy.
• Fig. 65B is a side view of a further remote phosphor system 6510.
• Blue LED 6511 radiates into first collimator 6512, forming blue beam b.
• Inclined mirror 6513 which is transparent for longer wavelengths and partially reflective for blue wavelengths, reflects the short wavelengths of the blue light, similarly to filter 6503 of FIG. 65A.
• This short wavelength light is shown as beam s entering second concentrator 6514 (shown in this figure as a CPC) and being concentrated upon phosphor patch 6515, the bottom of which is surrounded by a white reflector (not shown), so that all its yellow light goes upwards and is collimated by CPC 6514 into yellow beam y.
• Diagonal yellow reflector 6516 sends yellow beam y out in coincidence with longwave-blue output beam bL, the two comprising a white narrow-angle ( ⁇ 10°) output beam with uniform luminance and chrominance.
• Auxiliary mirror 6517 recycles unabsorbed short-wave blue light back into CPC 6514.
• the square shape of LED 6511 and its subsequent incomplete filling of CPC 6512 is the only luminance decrement suffered by this preferred embodiment.
• Also shown are large heat exchanger 6518, for LED 6511 , and small heat exchanger 6519 for phosphor patch 6515. Dotted lines 651Og denote tiny gaps similar to gaps 398 and 399 of FIG.
• Filter 6513 can alternatively be a long-pass filter, which has partial reflectance for some or all the blue wavelengths.
• FIG. 66B shows graph 6610 with horizontal axis 6611 for wavelength in nanometers and vertical axes 6612R on the left for % reflectance and 6612T on the right for % transmittance.
• Reflectance function 6613 comprises horizontal segment 6613 showing how filter 6513 is transparent in the longer wavelengths and is 70% reflective for wavelengths of blue LED 6511 , so that 30% of the blue light will transmit through filter 6513 and directly exit the device. The remaining 70% of the blue light will be reflected by filter 6513, eventually striking phosphor patch 6515.
• FIG. 65C shows a further remote phosphor system with phosphor patch and LED in the same plane.
• Remote phosphor system 6520 comprises blue LED 6521 , circularly symmetrical optic shown in this drawing as CPC 6522, diagonal all-wavelength mirror 6523, diagonal cyan-reflecting bandpass filter 6524, second circularly symmetrical optic shown in this drawing as CPC 6526 with diagonal all-wavelength mirror 6525, and diagonal yellow reflector 6528.
• 65C has filter reflectance curve 6605 of FlG. 66A, such that it transmits both the short-wavelength blue light that stimulates the phosphor and the yellow light emitted thereby, which has the spectral distribution graphed by curve 6606.
• Reflector 6524 only reflects the long- wavelength blue light into the white output beam formed by it and the yellow light reflected upward by mirror 6528.
• Fiat mirror 6529 of FIG. 65C recycles any light sent downward to it by filter 6524 and sends it back to same, which in turn redirects it back to mirror 6525, the light eventually ending at phosphor patch 6515, where it has another chance to be converted.
• Filter 6524 of FIG. 65C can alternatively be a long-pass filter, shown by FIG. 66C, which depicts graph 6630 with horizontal axis 6631 for wavelength in nanometers and vertical axis 6632 for % reflectance.
• Filter function 6633 comprises horizontal segment 6633h denoting a partial reflectance of 30% for a portion or the full range of blue wavelengths, as was described earlier, and steep- cutoff cliff 6633c.
• Dotted line 6636 graphs the reflectance of yellow filter 6528 of FIG. 65C 1 for spectral function 6635 of the phosphor.
• the assemblage comprising filters 6528, 6524 and mirror of 6529 of FIG. 65C can be rotated about an axis defined by the line that connects the centers of mirror 6523 and 6525. If this assemblage is rotated 90° about this axis, then light exiting remote phosphor system 6520 will be in a direction perpendicular to the original direction. This is a very useful configuration if it is desired that the height of remote phosphor system 6520 needs to be at a minimum, as is sometimes required for an architectural alcove application. Also, a mechanical swivel can be incorporated into 6520 to allow rotational positioning of this assemblage, so the direction of the output beam is adjustable about said axis.
• FIG. 65D shows an alternative remote phosphor embodiment to FIG. 65A 1 where the phosphor patch and LED lie approximately on the same plane.
• FIG. 65D depicts remote phosphor system 6530, comprising blue LED 6532 with thermal management device 6531. Blue light from LED 6532 is directed into first collimator 6533 (shown in this figure as a CPC), which collimates its light onto tilted long-pass dichroic filter 6534, having the same characteristics as filter 6503 of FIG. 65A, as described in FIG. 66A.
• Dichroic filter 6534 lies at 45 degree to collimator 6533 (shown in this figure as a CPC), reflecting all the short wavelengths of blue light leftward into second tilted long blue-pass dichroic filter 6536 (not visible).
• Filter 6536 has the same wavelength characteristics as filter 6534.
• Filter 6536 redirects the short blue wavelength light downward into optic 6537, which in turn concentrates the light onto thick phosphor patch 6538, which is enclosed by white reflector 6539, so that virtually all this blue light is converted into yellow light of much higher efficacy.
• White reflector 6539 incorporates a heat management element such as a heat exchanger with fins.
• the yellow converted light is emitted upward into optic 6537, and is collimated onto tilted long blue-pass filter 6536 thereafter forming yellow output beam 6540.
• the longer blue wavelengths which pass through filter 6534 will form blue output beam 6541.
• the blue and yellow beams can be recombined by any of the multi-wavelength methods of FIG. 40 through FIG. 50.
• solid dielectric triangular prisms 6542 having sides 6535.
• Prisms 6542 prevent collimated light from collimators 6533 and 6537 from being deflected at the face of filters 6534 and 6536.
• embodiment 6530 can be configured with open reflectors in which case prisms 6542 are no longer required.
• FIG. 65E is an alternative configuration of the embodiment shown in FIG. 65B, but where the LED and phosphor patch lie on the same plane.
• FIG. 65E depicts remote phosphor system 6545, comprising blue LED 6550 with thermal management device 6561.
• Blue light from LED 6550 is directed into first circularly symmetric collimator 6551 (which is shown in this case as a CPC), which collimates light into long-pass filter 6555 with partial reflectance for some or all of the blue wavelengths from blue LED 6550.
• Filter 6555 lets through a predetermined fraction of blue light and reflects the remainder of the blue light to all-wavelength reflector 6556. Blue light which is not reflected by filter 6555, exits as collimated blue beam b 6557.
• All-wavelength reflector 6556 Light striking all-wavelength reflector 6556 is turned ninety degrees downward into circularly symmetrical concentrator 6559 (which is shown in this case as a CPC), where it strikes thick phosphor patch 6560, the bottom of which is surrounded by a white reflector (not shown), so that all its yellow light goes upwards and is collimated by 6559. All-wavelength mirror 6556 redirects this collimated light to blue short-pass filter 6553 (which is at a 45 degree angle with respect to it), reflecting all the yellow and longer wavelengths emitted by the phosphor patch out of the device as collimated yellow beam y 6558. Blue beam b 6557 and yellow beam y 6558 combine to produce white light.
• FIG. 66D depicts graph 6640 with horizontal axis 6641 for wavelength in nanometers and vertical axis 6642 for % reflectance.
• Filter function 6643 which corresponds to filter 6555 of FIG. 65E, comprises horizontal segment 6643h denoting a partial reflectance of 70% for a portion or the full range of blue wavelengths and steep-cutoff cliff 6643c.
• Dotted line 6646 is the reflectance function of filter 6553 of FIG. 65E, shaped to fit phosphor spectrum 6645.
• Thermal management device 6561 is shown as being common to blue LED 6550 and phosphor patch 6560. However, in practice there can be a thermal break in this device so that the phosphor patch does not receive a significant amount of heat back from the LED and vice versa.
• the efficiency of the remote phosphor system depends upon the effectiveness of its dichroic filter.
• actual spectral transmittance measurement data has been made available by its manufacturer, JDS Uniphase of California, USA.
• the performance and other specifications relating to this filter were provided to this company by the Inventors so as to work in an actual remote phosphor system designed by the Inventors in the embodiment shown in Figures 63A and 64B.
• FlG. 67 shows graph 6700 with horizontal axis 6701 for immersed wavelength and vertical axis 6702 for percent transmittance.
• Theoretical performance is indicated by solid line 6703 and measured performance by dashed line 6704.
• Transmitting spectral region T comprises values of 99.3 to 99.9%.
• Reflecting spectral region R comprises 99.9% reflectance, with unmeasurably small absorption. This demonstrates the feasibility of the invention.
• FIG. 68A is a perspective view of remote phosphor system 680, comprising blue LED 681 , 10° dielectric crossed CPC 682, blue-pass filter 683, 15° dielectric crossed CPC 684, and phosphor patch 685, which is 50% larger than LED 681.
• FIG. 68B is a view of a rectangular cross section CPC 6810. The face extending between edges 6812 and 6817 and the opposite face extending between edges 6814 and 6816 are shaped as a linearly extruded CPC profile.
• FIG. 69A is a side view of remote phosphor system 690.
• Blue LED 691 shines into CPC 692, which collimates its light into blue beam b with divergence ⁇ (here 10°).
• Diagonal mirror 693 sends these rays laterally into upper diagonal blue-reflecting mirror 695, which reflects a portion of the blue light outward, and also diagonal blue-reflecting mirror 694, which redirects it downwards into smaller second CPC 697, which is a rectangular cross section CPC similar to the one described in FIG. 68B.
• Phosphor patch 698 receives the blue light reflected by diagonal blue-reflecting mirror 694 and converts it to yellow light, which CPC 697 collimates into yellow output beam y (with larger divergence ⁇ , here 15°) which passes through mirrors 694 and 695.
• Large heat exchanger 699L cools blue LED 691 while small heat exchanger 699S cools phosphor patch 698.
• Dotted lines denote tiny air gaps similar to gaps 398 and 399 of FIG. 39B.
• This configuration has the optical drawback that the yellow and blue output beams will not properly combine because of their differing divergences ⁇ and ⁇ .
• the smaller size of upper blue-reflecting mirror 695 means that the beam is not spatially uniform either.
• FIG. 69B shows the same system, but with the addition of holographic diffuser 69Od, which widens the ⁇ 10° blue light from CPC 692 so that its divergence angle equals the ⁇ 15° from CPC 697.
• Blue-reflecting mirror 695 must be long enough to reflect all this blue light towards the exit port. Now the two beams will join in the far field to make white light. In the near field, however, the two beams are not coincident.
• FIG. 69C shows the same system, but with the upper blue mirror shown split into two smaller mirrors 695s. Further such splitting into mirrors too small to discern would give a spatially uniform white output.
• FIG. 70 shows remote phosphor system 7000.
• Blue LED 7010 cooled by large heat exchanger 7011 , shines into first CPC 7020, which collimates its light to rays b with ⁇ 10° divergence.
• Diagonal mirror 7030 transmits part of this light, after which it is spread to ⁇ 15° divergence by diffuser 7040. Then it passes through yellow-reflecting diagonal mirror 7050 and exits.
• Diagonal mirror 7030 also laterally reflects part of rays b, to blue-reflecting diagonal mirror 7070, which reflects them downward into second CPC 7080, which in turn concentrates them onto phosphor patch 7090 (cooled by heat exchanger 7091).
• Diagonal mirror 7030 could be a conventional beam-splitter (with about 2/3 ⁇ reflectance, 1/3 rd transmittance), or alternatively a beam-splitting blue mirror as described in FIG. 66D, which is a partial reflecting, in the short-wavelengths, long-pass filter. Since second CPC 7080 has equal aperture to first CPC 7020 but a larger acceptance angle, phosphor patch 7090 is proportionately larger as well. Rod 7081 makes up for the shorter height of second CPC 709Q as compared with first CPC 7020. Dotted lines denote tiny air gaps similar to gaps 398 and 399 of FIG. 39B.
• FIG. 71 is a perspective view of remote phosphor system 7100 based on the embodiment of FIG.
• Blue LEDs 7110 are arrayed 4x4, each coupled to small crossed CPC 7120, which in turn are all joined to rectangular mixing duct 7130. Over it lie diagonal partial blue-mirrors 7140, reflecting some blue light laterally into diagonal blue mirrors 7150, thence downward into large CPCs 7160, which concentrate the blue light onto phosphor patches 7170. Their yellow light is collimated by large CPCs 7160 and passes through diagonal blue mirrors 7150, to strike diagonal folding mirrors 7180 and be reflected laterally inwards thereby.
• Diagonal blue- passing yellow mirrors 7190 send the yellow light out in coincidence with the blue light (which was widened by diffusers 7195) to form a white output beam. All the LEDs and phosphor patches conveniently lie in the same plane. [0437] In scaling to higher power via a greater number of blue LEDs, for the embodiments of FIG. 63A and FIG. 63B, the dielectric CPC proves too bulky and expensive. Instead, the cone and lens arrangement of FIG. 6C can be utilized. Accordingly, FIG. 72A shows remote phosphor system 7200, with 32 blue LEDs 7201 , each with its own crossed dielectric CPC 7202, arrayed in an incomplete square on the filter and mirror plane 7203.
• Cone 7205 has a metallic backing, connected to radial heat-exchanger fins 7210.
• Cone 7205 is not limited to the conical cross-section demanded by the use of mirror foil, but can also have a tailored cross-section, as would be made with injection ' molding.
• Such tailored shapes known to those skilled in the field of nonimaging optics, are normally designed in conjunction with lens 7204, shown in FIG. 72B.
• Such combination lens/reflector optics can perform near the theoretical limit.
• the refractive lens should be fully multi-coated and the reflector should have near 100% reflectance over the required wavelengths.
• Multi-coated, high transmittance lenses are available from numerous sources. Very high reflectance coatings on non-developable surfaces are available from industry sources. Also, some high reflectance films such as those available from 3M of Minnesota, USA, have successfully been molded into non-developable shapes. Such films can also be used for making conical reflectors, such as Cone 7205, since a cone is a developable surface that can be made from flat film.
• 72B is another perspective view of remote phosphor system 7200, showing small crossed dielectric CPCs 7202, reflector cone 7205, refractive lens 7204 and heat-exchanger fins 7210. Also shown is central phosphor aperture 7207, surrounded by diffuse reflector 7206, backed by a highly conductive material connected to fins 7210 for conductive removal of the 5 Watts of waste heat from phosphor patch 7206.
• This system should be able to produce about 4000 lumens, at a luminance of 40 candela/mm 2 , exceeded only by arc lamps.
• FIG. 73A shows a preferred embodiment of a side-emitting remote phosphor system which has separate short and long-wave output ports.
• Remote phosphor system 7300 of FIG, 73A uses the principle of FIG. 68A where the acceptance angle of the second optic is larger than the optic coupled to the blue LED.
• the second optic has a rectangular cross-section while the first has a square section.
• Remote phosphor system 7300 comprises blue LED 7301 which radiates into first cross-CPC 7313 (or other collimator having a square cross-section) having acceptance angle 7302, which collimates light from blue LED 7301 to tilted mirror 7305 and an optical train with acceptance angle 7308, which concentrates the light onto remote phosphor patch 7309 with highly reflective cover and heat exchanger (both not shown).
• the portion of said blue light that strikes tilted mirror 7305 is reflected and re-directed to a short- wavelength output port, whose beam output is indicated by arrow 7311.
• the portion of blue light not striking mirror 7305 passes into said optical train, which is comprised of tilted short-pass filter 7306 (as described by FIG.
• CPC 7314 has said acceptance angle 7308 larger than cross-CPC 7313 with said acceptance angle 7302.
• Light emanating from phosphor patch 7309 is coilimated by rectangular cross-CPC 7314 toward tilted short-pass filter 7306, which reflects yellow and longer wavelength to long-wavelength output port, whose beam output is indicated by arrow 7312.
• Rectangular cross-section CPC 7314 has upper straight section 731Ou and lower straight section 73101, and in the orthogonal direction an expanding section (not shown), such as the geometry of FIG 68B.
• the beam angle of short-wave blue light indicated by arrow 7311 can optionally be diffused to match the beam angle for the light from the long-wavelength output port. These blue and yellow beams can be recombined by any of the multi-wavelength methods of FIG. 40 through FIG. 50.
• One advantage of embodiment 7300 is that the device does not require any air gaps and can be manufactured as a single piece. LED 7301 and phosphor patch 7309 lie approximately on a common axis so that remote phosphor system 7300 is thin in the vertical direction, making it suitable for applications requiring this attribute. Alternatively, the device could be configured with several air-gaps and all optical surfaces being fully multi-coated. [0440] FIG.
• Remote phosphor system 7320 of FIG. 73B uses the principle of FIG. 68A where the acceptance angle of the second optic is larger than the optic coupled to the blue LED.
• the second optic has a rectangular cross-section while the first has a square section.
• Remote phosphor system 7320 comprises blue LED 7321 which radiates into first cross-CPC 7329 (or other collimator having a square cross-section at each end), which collimates light from blue LED 7321 to tilted mirror 7323 and to diffuser 7324.
• the portion of the blue light striking diffuser 7324 (thick line) is expanded and exits the short-wavelength output port as beam output 7326.
• the portion of blue light reflected by mirror 7323 is again reflected by tilted yellow-pass filter 7325 towards the rectangular cross-section concentrator 7330, shown in section as a CPC on the bottom and a straight section on top.
• Concentrator 7330 has an acceptance angle equal to or greater than the output angle of cross-CPC 7329.
• Cross-CPC 7330 concentrates the blue light onto remote phosphor patch 7322 with highly reflective cover (not shown) and heat exchanger 7328.
• Rectangular cross-section CPC 7330 has a geometry similar to the one shown in FIG 68B. Diffuser 7324 expands the beam of blue light so that its angular aperture matches that of the yellow light coming out of collimator 7330.
• FIG. 73C shows an alternative configuration of the side-emitting embodiment of FIG. 73A of a remote phosphor system which has one common output port.
• Remote phosphor system 7340 of FIG. 73C uses the principle of FIG. 68A where the acceptance angle of the second optic is larger than the optic coupled to the blue LED.
• the second optic has a rectangular cross-section while the first has a square section.
• Remote phosphor system 7340 comprises blue LED 7341 which radiates into first cross-CPC 7347 (or other collimator having a square cross-section at each end) having acceptance angle 7342, which collimates light from blue LED 7341 to tilted mirror 7344 and an optical train with acceptance angle 7343, which concentrates the light onto remote phosphor patch 7342 with highly reflective cover and heat exchanger (both not shown).
• Mirror 7344 may be doubly curved and/or partially diffusive in such a way that the angular aperture of the blue light that is reflected on it increases from 7342 to 7343.
• the portion of said blue light that strikes tilted mirror 7344 is re-directed to an output port, whose beam output is indicated by arrow 7345.
• the portion of blue light not striking mirror 7344 passes into said optical train, which is comprised of tilted short-pass filter 7348 and rectangular cross-CPC 7346 (or other concentrator having a rectangular cross-section at each end) shown here in section as a CPC.
• CPC 7346 has said acceptance angle 7343 larger than cross-CPC 7347 with said acceptance angle 7342.
• Light emanating from phosphor patch 7342 is collimated by rectangular cross-CPC 7346 toward tilted short-pass filter 7348, which reflects yellow and longer wavelength to said output port, whose beam output is indicated by arrow 7345.
• One advantage of embodiment 7340 is that the device does not require any gaps and can be manufactured as a single piece.
• the device could be configured with gaps at the wider end of CPC 7347 and wider end of CPC 7346 and all optical surfaces at the gaps being either fully multi-coated (in the case of air gaps) or filled with a lower-index of refraction material such as a silicone. This modification would make said output port of a minimal size.
• the color temperature of the remote phosphor systems described above is the result of how much blue light is let out by the various filters. Since the filters have an unalterable spectral reflectance function, this color temperature is not readily adjustable. Accordingly, the following five preferred embodiments have means to add a second bl,ue LED so that all the light from the first blue LED is totally absorbed by the phosphor. Then the color temperature goes up with increased output from the second LED, or decreased output of the first LED, which powers the phosphor.
• FIG. 74 shows remote phosphor system 7400, comprising first blue LED 7401 , first collimator 7402 (shown as a CPC) optically coupled thereto with 10° concentration, second blue LED 7403, second collimator 7404 (shown as a CPC), optically coupled thereto with 15° concentration and oriented orthogonal to the first collimator 7402, inclined short-pass filter 7405 (described by FIG. 11A), concentrator 7406 (shown as a CPC) receiving light rays b1 from first collimator 7402 and concentrating them upon phosphor patch 7407 with highly reflective cover and heat exchanger (both not shown).
• first blue LED 7401 shown as a CPC
• first collimator 7402 shown as a CPC
• second collimator 7404 shown as a CPC
• concentrator 7406 shown as a CPC
• phosphor 7407 radiates yellow light which is collimated into beam y by concentrator 7406 (acting as collimator for rays in the reverse direction).
• Inclined short-pass filter 7405 reflects said yellow light coincident with rays b2 coming directly from second collimator 7404.
• Changes in the output of second blue LED 7403, relative to the output of first collimator 7401 cause concomitant changes in the color temperature of the white output of coincident output beams y and b2.
• FiG. 75 shows a similar system with the two LEDs and the phosphor patch conveniently in the same plane.
• Remote phosphor system 7500 comprises first blue LED 7501 , optically coupled to first collimator 7502 (shown as a cross- CPC), which coilimates its light to 10°, inclined long-pass filter 7503, inclined all- wavelength mirror 7504, concentrator 7505 (shown as a cross-CPC) with 15° acceptance angle, remote phosphor patch 7506 with highly reflective cover and heat exchanger (both not shown), second LED 7507, collimator 7508, which coilimates its light to 15°, expander-mixer section 7509, inclined short-pass filter 7510, and five diagonal prism blocks 7511 with narrow gaps 7512, preferably filled with lower-index of refraction silicone.
• Collimated white output beam 7520 is composed of two coincident beams, yellow from the phosphor and blue from second blue LED 7507. Its color temperature is controlled by the relative outputs of the two blue LEDs.
• FIG. 76 shows an alternative embodiment to that of FIG. 75, where the two LEDs and the phosphor patch are in the same plane, but having a central output beam location.
• Remote phosphor system 7600 comprises first blue LED
• collimated white output beam 7608 is comprised of two coincident beams, yellow from the phosphor and blue from second blue LED
• FIG. 71 illustrates how an array of LEDs and an array of phosphor patches can be combined into a single output device by a logical extension of the principles taught in the embodiment of FIG. 70.
• Such logical extension can be applied for all the embodiments of the remote phosphor systems taught herein, except those embodiments, such as FIG. 65A and FIG 65B 1 which have separate short-wave and long-wave output ports.
• an array of LEDs and array of phosphor patches can be accommodated but with the requirement that there are at least two output ports.
• FIG. 77 To further illustrate how a remote phosphor embodiment with a single output port can be logically extended to include an array of components, we accordingly provide the embodiment shown in FIG. 77.
• FIG. 77 shows a system with the eight LEDs and four phosphor patches conveniently located on the same plane.
• Remote phosphor system 7700 comprises first array of blue LEDs 7702, optically coupled to first array of four collimators 7706 (shown as cross-CPCs), which collimates light to 10°, inclined long-pass filter 7709, inclined all-wavelength mirror 7708, array of four concentrators 7707 (shown as a cross-CPCs) with 15° acceptance angle, array of four remote phosphor patches 7701, each with highly reflective cover and heat exchanger (both not shown), second array of four LEDs 7703, array of four collimators 7704, which collimates light to 15°, expander-mixer section 7705, inclined short-pass filter 7710, and five diagonal prism blocks 7711 with narrow gaps 7713, preferably filled with lower-index of refraction material, such as silicone.
• Collimated white output beam 7712 from a single output port is comprised of two coincident beams, yellow from the phosphor and blue from second array of blue LEDs 7703. Its color temperature is controlled by the relative outputs of the two arrays of blue LEDs.
• FIG. 77 Other hybrid configurations are also possible for the embodiment of FIG. 77.
• the array of four remote phosphor patches 7701 can be combined into one phosphor patch, by converting the array of four concentrators 7707 into a single collimator.
• This principle is illustrated in FIG. 71 by the large CPCs 7160, where each of the two large CPCs of 7160 accepts the light from four blue LEDs.
• FIG. 78 shows remote phosphor system 7800, which allows the color temperature of its emitted white light to be tunable, by adjusting the ratio of the flux output of two blue LEDs.
• This embodiment is based on the principles taught in FIG. 73C, where in this embodiment blue LED 7341 , collimator 7347 and tilted short-pass flter 7348 are replaced respectively by LEDs 7801 and 7802, collimators 7808 and 7807, and tilted short-pass filter 7803.
• Blue light emitted by blue LED 7801 is partially reflected by mirror/diffuser 7805, which diffuses this light so it matches the angular aperture of the yellow light coming out of collimator 7810.
• Yellow phosphor 7804 receives light from both blue LEDs 7802 and 7801 , and therefore the yellow component of the emitted white light depends on the output of both blue LEDs.
• the blue component of the emitted white light results only from the reflection of blue light from blue LED 7801 at mirror/diffuser 7805. Varying the output of blue LED 7801 respect to that of blue LED 7802 allows a considerable control over the color temperature of emitted white light 7806.
• FIG. 79 shows remote phosphor system 7900 that has a tunable color temperature and employs a hybrid system that has partial recycling and partial non-recycling.
• Remote phosphor system 7900 comprises three blue LEDs 7903 and two phosphor patches 7901 and 7902, all five of which are co-planar.
• Collimator 7917 which receives blue light from central blue LED 7903 is configured so that its acceptance angle is equal to the acceptance angles of concentrators 7914 and 7912. In this embodiment this acceptance angle is set to 15° and the profiles of 7917, 7914 and 7912 are shown as CPCs.
• Embodiment 7900 further comprises right triangular short-pass filter 7908, all-wavelength folding mirrors 7904 and 7905, tilted long-pass filters 7906 and 7907, gaps 7910 fully multi-coated (in the case of air gaps) or filled with a lower-index of refraction material, and output port 7911.
• Blue light from central LED 7903 is collimated by collimator 7917, which directs it to mixer-section 7916, which can also be configured as an expander-mixer section similar to section 7509 of FIG. 75.
• Blue light from mixer-section 7916 is transmitted through a low-index of refraction gap (shown as a dotted line) and triangular short-pass filter 7908, whereupon it exits output port 7911.
• Light from right and left blue LEDs 7903 is collimated respectively by collimators 7913 and 7915 and long-pass filters 7907 and 7906, whereupon each blue beam is directed by all-wavelength folding mirrors 7905 and 7904 into an optical train which has an exit port having a remote phosphor patch.
• Each phosphor patch will have a highly reflector cover and typically a heat- management means (both not shown).
• Each half of 7900 operates in this regard the same as the embodiment of FIG.
• the fraction of light that is intercepted by triangular short-pass filter 7908 is adjustable by choosing appropriate shape and acceptance angles for collimator 7917 and expander-mixer 7916. For example, if collimator 7917 and mixer 7916 is replaced with collimator 7508 and expander-mixer 7509, then the fraction of light intercepted on each pass by short-pass filter 7908 will be 50%.
• the color temperature of system 7900 can be adjusted by varying the flux output of central blue LED of 7903, relative to the flux of the two blue LEDs that are designated for phosphor conversion.
• FIG. 80 shows remote system 8000 which is an alternative embodiment of the one of FIG. 79 where the all-wavelength folding mirrors 7904 and 7905 are not required.
• Remote phosphor system 8000 comprises, blue LEDs 8012, square-section collimators 8010, both on the left side, adjustable blue LED 8001 with collimator 8004, phosphor patches 8003 (with highly reflective cover and heat sinks not shown) and associated square-section concentrators 8005, optional mixing chamber 8006, all-wavelength mirrors 8008, tilted short-pass filter 8002, output port 8007 and gaps (shown as dotted lines).
• Flux of output port 8007 is represented by flux arrow 8011 , which is the combined output of adjustable blue LED 8001 and reflected yellow and longer wavelengths from short-pass filter 8002.
• Light reflected by short-pass filter 8002 not exiting output port 8007 is reflected by all-wavelength mirrors 8008 and back to short-pass filter 8002, which in turn reflects it to the optical train of optional mixing chamber 8006, concentrators 8005, and finally back to phosphor patches 8003.
• Phosphor patches 8003 receive this non-exiting light, scattering and recycling it.
• FIG. 80 is configured with two blue LEDs 8012 but this could easily be expanded by adding more paired elements 8010 and 8005 to the vertical stack. Also blue LED 8001 could also be configured as a larger array of LEDs by adding more LEDs and collimators 8004, by application of the principles of the embodiment of FIG. 77.
• FIG. 77 shows a preferred embodiment with multiple LEDs and phosphor patches, enough to make it easy to envisage preferred embodiments with even greater numbers of LEDs and phosphor patches, which are difficult to illustrate clearly, as FIG. 72A shows. It is possible for these phosphor patches be green-emitting instead of the conventional yellow type, and some red LEDs added, as discussed regarding FIG. 10E. It is also possible that some blue LEDs stimulate the green phosphor while others contribute directly to the output beam.
• the red LEDs can either be located in second array of LEDs 7703 of FIG. 77 in which case short-pass filter 7710 directly above the red LEDs, must be changed to a long-pass filter to allow the red light to be transmitted while being reflective to the wavelengths of the green phosphor. Alternatively the red LEDs can be located within first array of LEDs 7701. This latter approach does not require a filter change to the system.
• the green phosphor is advantageous over the green LEDs used in, for example, the preferred embodiments of FIG. 40 through FlG. 51 , both because of its superior efficacy (green LEDs presently have much lower external quantum efficiency than blue LEDs, so much so that the green phosphor's conversion losses are far less) and because it has a wider wavelength range. This results in both better color rendering and less color separation by the eye's longitudinal chromatic aberration, which tends to cause noticeable artifacts in conventional narrowband RGB LEDs for such imaging applications as projection television and backlights.
• Such wavelength spreading is also possible with the blue and red LEDs in such an approach, by using both 450nm and 472 nm blue LEDs, and several of the many red wavelengths available, such as 610, 625, and 640 nm.
• a multiwavelength light source can be run in color-sequential mode, with the red, green, and blue outputs, each powered separately for a third of the television frame-time to illuminate a monochrome spatial light modulator, such as an LCD.
• These have much higher throughput (30-50%) than conventional white-light color LCDs (3-5%), which have inefficient color filters that waste most of the input white light.
• the multi-LED approach of FIG. 77 can be applied to the recycling configurations of FIG. 79 and FIG. 80, which show only single LEDs. Vigorous cooling of the LEDs enables them to be overdriven for maximal luminosity, while highly efficient recycling enables even smaller apertures than in FIG. 79 to be used without excessive sacrifice of overall luminosity.
• This approach enables the luminance levels of arc lamps (300 cd/mm 2 mean) to be achieved, without their cost, bulk, fragility, high temperatures, and short life.
• Arc lamps also require mixing and condensing optics (of mediocre optical efficiency at best) to overcome their nonuniform luminance and lack of a sharp border, leading to much lower deliverable luminance.
• the present invention delivers maximal luminance in a narrow-angle ( ⁇ 15°) beam with high spatial uniformity and a very sharp border, with optical efficiency no worse than arc lamps.
• a solid-state lighting system offers both tunable output chromaticity for general lighting and color-sequential illumination for projection television, without the disadvantageous narrowband spectra of RGB LED systems of the prior art.
• the description herein describes both individual optical elements and several embodiments that combine them as building blocks.
• One common theme of many of these elements and their combinations is preservation of source luminance through etendue preservation, using novel applications of the principles of non-imaging optics.

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