# US 12,192,684 B2 · Patch correction for light steering projector

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- Number: US 12,192,684 B2
- Document ID: US12192684B2
- Status: Granted
- Kind: B2
- Application number: 18/365,173
- Filed: 2023-08-03
- Published: 2024-03-07
- Granted: 2025-01-07
- Earliest claimed: 2021-02-16
- Assignees: Barco Visual Solutions, Inc.
- Applicants: Barco Visual Solutions, Inc.
- Inventors: Samuel Melamed; Martin Gregory Beckett; Raveen Kumaran; Weicheng Yan
- Web page: https://patentgrep.com/patent/US12192684B2

## CPC

- H04N 9/312: {Driving therefor (driving of electronic spatial light modulators in displays other than projection devices G09G3/34, G09G3/36; control of liquid crystal elements G02F1/133; control of micromechanical modulators G02B26/08)}
- H04N 9/3164: {using multiple light sources}
- G02B 19/0066: {in the form of an LED array}
- G02B 26/06: for controlling the phase of light (G02B26/08 takes precedence {, measuring optical phase difference G01J9/00})
- G02B 27/0933: {Systems for active beam shaping by rapid movement of an element}
- G02B 27/0944: {Diffractive optical elements, e.g. gratings, holograms (gratings per se G02B5/18; holograms used as optical elements per se G02B5/32)}
- G02B 27/0961: {Lens arrays (lens arrays per se G02B3/0006)}
- G03H 1/0005: {Adaptation of holography to specific applications (holographic optical element G02B5/32; holographic scanner G02B26/106; recognition using holographic mask G06V10/88; holographic memories G11B7/0065, G11C13/042)}
- G03H 1/2294: {Addressing the hologram to an active spatial light modulator}
- H04N 9/3126: {for spatial light modulators in series}
- H04N 9/3138: {using arrays of modulated light sources (electroluminescent display devices G09G3/30)}
- H04N 9/3152: {for shaping the light beam (beam shaping per se G02B27/09)}
- H04N 9/3155: {for controlling the light source (light source control per se H05B35/00 – H05B47/00; control of an illumination source for displays in general G09G3/3406)}
- H04N 9/317: {Convergence or focusing systems (electronic adjustment of convergence H04N9/3185; convergence or focusing arrangements for cathode ray tubes H04N9/28; means for automatic focusing of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/53)}
- H04N 9/3185: {Geometric adjustment, e.g. keystone or convergence (optical or mechanical adjustment of convergence H04N9/317; using scanning means H04N3/22; optical or mechanical adjustments of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/14)}
- H04N 9/3194: {including sensor feedback}
- G03H 1/32: Systems for obtaining speckle elimination
- G03H 2222/34: Multiple light sources
- G03H 2222/35: Transverse intensity distribution of the light beam
- G03H 2223/14: Diffuser, e.g. lens array, random phase mask
- G03H 2223/16: Optical waveguide, e.g. optical fibre, rod
- G03H 2223/17: Element having optical power
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G03H: HOLOGRAPHIC PROCESSES OR APPARATUS (holograms, e.g. point holograms, used as ordinary optical elements G02B5/32; producing stereoscopic or other three-dimensional effects G02B30/00; diffraction-grating systems G02B27/44; systems using moiré fringes G02B27/60; optical logic elements G02F3/00; stereo-photography G03B35/00; photosensitive materials or processes for photographic purposes G03C; {stereo-photographic or similar processes G03C9/00}; apparatus for processing exposed photographic materials G03D; analogue computers performing mathematical operations with the aid of optical elements G06E3/00; authentication by radiation, of concealed information carried by holograms or diffraction gratings G06K19/16; holographic storage G11B7/0065, G11C13/04; {stereoscopic or other three dimensional effects in television systems H04N13/00})

## Abstract

Example embodiments provide systems and methods for correcting non-uniformities of a light beam generated by a multi-emitter light source. In some embodiments a phase modulator displays patch lenses to correct for the non-uniformities. In some embodiments each region of the phase modulator is illuminated by a beam generated by one emitter of the multi-emitter light source. Such region of the phase modulator may display a patch lens for correcting non-uniformities in the corresponding beam which illuminates the region.

## Claims

### Claim 1

A projection system comprising:
one or more light sources operable to emit a plurality of light beams;
a phase modulator comprising a two-dimensional array of pixels, the pixels controllable to retard phase of light incident on the pixels by variable amounts, the phase modulator having an active area in an optical path of the plurality of light beams, each of the plurality of light beams incident on the active area of the phase modulator in a corresponding one of a plurality of distinct regions of the active area of the phase modulator;
a controller configured to set the pixels of each of the distinct regions of the phase modulator to display an optical form for a patch lens corresponding to the distinct region, the patch lens is configured to correct for non-uniformities in at least one of:
pointing parallelism between the plurality of light beams; and
collimation of the one of the beams of light.

### Claim 2 (depends on 1)

The projector according to claim 1 wherein the distinct regions are arranged in an array comprising a plurality of rows and a plurality of columns.

### Claim 3 (depends on 1)

The projector according to claim 1 wherein the light source comprises a multi-emitter light source comprising at least two rows and two columns of light emitters.

### Claim 4 (depends on 1)

The projector according to claim 1 wherein the controller is configured to set the pixels of each of the distinct regions of the phase modulator to display a light steering phase pattern combined with the optical form for the corresponding patch lens.

### Claim 5 (depends on 1)

The projector according to claim 1 wherein the optical form for the patch lens corresponding to the distinct region is at least partially based on measured deviations from ideal of the corresponding light beam.

### Claim 6 (depends on 1)

The projector according to claim 1 wherein the optical form for the patch lens corresponding to the distinct region is at least partially based on measured deviations from ideal of a light field produced at an image plane after the corresponding light beam has interacted with the phase modulator.

### Claim 7 (depends on 1)

The projector according to claim 1 wherein the patch lens is configured to correct for non-uniformities comprising intensity distribution.

### Claim 8 (depends on 1)

The projector according to claim 1 wherein the displayed optical forms correspond to optical forms for spherical lenses.

### Claim 9 (depends on 1)

The projector according to claim 1 wherein the optical form of each patch lens is generated independently.

### Claim 10 (depends on 1)

The projector according to claim 1 wherein the optical form of each patch lens is generated by the controller configured to execute an optimization process.

### Claim 11 (depends on 10)

The projector according to claim 10 wherein the optimization process comprises iteratively varying phase shifts of the pixels of the corresponding patch lens until one or more observed characteristics of a corresponding output beam indicate that the patch lens is suitably correcting for deviations from ideal of the light beam.

### Claim 12 (depends on 10)

The projector according to claim 10 wherein the optimization process is executed sequentially for different ones of the plurality of patch lenses.

### Claim 13 (depends on 10)

The projector according to claim 10 wherein the optimization process is executed in parallel for different ones of the plurality of patch lenses.

### Claim 14 (depends on 10)

The projector according to claim 10 wherein the optimization process comprises performing simulated annealing to find phase shifts for the pixels in the region which will make up the phase pattern for the corresponding patch lens.

### Claim 15 (depends on 1)

The projector according to claim 1 wherein the optical form for each of the patch lenses specifies at least one of focal length, optical centre shift, parameterized astigmatism and tilt of the corresponding patch lens.

### Claim 16 (depends on 1)

The projector according to claim 1 wherein at least one of the distinct regions is divided into a plurality of sub regions and the controller is configured to set the pixels of each of the sub regions to display an optical form corresponding to the sub region.

### Claim 17 (depends on 1)

The projector according to claim 1 wherein different parts of a single light beam illuminate two or more sub regions of a corresponding distinct region of the phase modulator.

### Claim 18 (depends on 1)

The projector according to claim 1 wherein at least one of the optical forms corresponds to a plurality of lenses superposed on one another.

### Claim 19 (depends on 1)

The projector according to claim 1 wherein at least one of the light beams extends over a plurality of the distinct regions.

### Claim 20 (depends on 1)

The projector according to claim 1 wherein one or more of the optical forms is respectively varied in real time to account for varying characteristics of a corresponding one of the light beams.

### Claim 21 (depends on 1)

The projector according to claim 1 wherein the optical form applied to each of the light beams further comprises a light steering component to steer light.

### Claim 22 (depends on 21)

The projector according to claim 21 wherein the corresponding patch lens and the corresponding light steering component are superposed.

### Claim 23 (depends on 21)

The projector according to claim 21 wherein the light steering components are configured to steer the light beams to converge at a plurality of different points.

### Claim 24 (depends on 21)

The projector according to claim 21 wherein the controller controls each of the distinct regions of the phase modulator individually to display a pattern of phase shifts which steers light from the corresponding light beam.

### Claim 25 (depends on 1)

The projector according to claim 1 comprising receiving optics upstream from the phase modulator, the receiving optics configured to shape or modify the light beams to better illuminate the phase modulator.

### Claim 26 (depends on 25)

The projector according to claim 25 wherein the receiving optics shape light from the light beams for the light to match a size of the two-dimensional array of pixels.

### Claim 27 (depends on 1)

The projector according to claim 1 wherein the controller is configured to set at least a portion of the pixels of the phase modulator to display phase patterns selected to cause specular reflection of at least a portion of the light beams.

### Claim 28 (depends on 27)

The projector according to claim 27 wherein the controller is configured to dynamically vary the number of pixels in the portion of pixels to adjust a ratio of unsteered light to steered light.

### Claim 29 (depends on 28)

The projector according to claim 28 wherein the controller is configured to determine a desired ratio of unsteered light to steered light based at least in part on processing image data.

### Claim 30 (depends on 29)

The projector according to claim 29 wherein the controller is configured to determine a desired ratio of unsteered light to steered light based at least in part on one or more of: black level of the image data, maximum luminance of highlights in the image data and contrast of the image data.

### Claim 31

A projection system comprising:
one or more light sources operable to emit a plurality of light beams;
a phase modulator comprising a two-dimensional array of pixels, the pixels controllable to retard phase of light incident on the pixels by variable amounts, the phase modulator having an active area in an optical path of the plurality of light beams, each of the plurality of light beams incident on the active area of the phase modulator in a corresponding one of a plurality of distinct regions of the active area of the phase modulator;
a controller configured to set the pixels of each of the distinct regions of the phase modulator to display an optical form for a patch lens corresponding to the distinct region, the patch lens is configured to correct for non-uniformities present in the corresponding one of the beams of light; and
a combining rod downstream from the phase modulator, the combining rod having entrance and exit apertures and light reflecting potions on opposing sides of a central longitudinal axis of the combining rod, the combining rod configured to combine steered and unsteered light and to homogenize the unsteered light by multiple reflections from the reflecting portions before reaching the exit aperture.

### Claim 32 (depends on 31)

The projector of claim 31 wherein the combining rod is a passive optical device.

### Claim 33 (depends on 31)

The projector of claim 31 wherein the combining rod comprises a hollow tube.

### Claim 34 (depends on 31)

The projector of claim 31 wherein the combining rod comprises a solid body of transparent material.

### Claim 35 (depends on 34)

The projector of claim 34 wherein the transparent material is at least one of glass, quartz and transparent plastic.

### Claim 36 (depends on 34)

The projector of claim 34 wherein the solid body comprises a light reflective or light scattering layer or coating.

### Claim 37 (depends on 31)

The projector of claim 31 wherein the combining rod comprises a hollow rectangular tube having at least one tapered face.

### Claim 38 (depends on 31)

The projector of claim 31 wherein the combining rod comprises two reflective plane surfaces which taper from the entrance aperture to the exit aperture, the entrance aperture larger than the exit aperture.

### Claim 39 (depends on 31)

The projector of claim 31 wherein the combining rod is tapered in one plane.

### Claim 40 (depends on 39)

The projector of claim 39 wherein the combining rod is tapered along a horizontal axis of the combining rod.

### Claim 41 (depends on 39)

The projector of claim 39 wherein the combining rod is tapered along a vertical axis of the combining rod.

### Claim 42 (depends on 31)

The projector of claim 31 wherein the combining rod comprises a twisted rod.

### Claim 43 (depends on 42)

The projector of claim 42 wherein the twisted rod comprises at least one turn of about 90°.

### Claim 44 (depends on 31)

The projector of claim 31 wherein the combining rod comprises a body having a concave shape.

### Claim 45 (depends on 31)

The projector of claim 31 wherein output angles of light from the exit aperture are about 45° or less.

### Claim 46 (depends on 31)

The projector of claim 31 wherein the combining rod is configured to provide a generally symmetric output.

### Claim 47 (depends on 31)

The projector of claim 31 further comprising a prism optically coupled to the combining rod proximate to the entrance aperture, the prism configured to collect the unsteered light and transmit the unsteered light into the combining rod.

### Claim 48 (depends on 31)

The projector of claim 31 further comprising optical elements to deliver the steered and unsteered light from the phase modulator to the combining rod.

### Claim 49 (depends on 48)

The projector of claim 48 wherein the optical elements comprise a physical lens positioned between the phase modulator and the combining rod.

### Claim 50 (depends on 49)

The projector of claim 49 wherein the physical lens is positioned at a location which maximizes incidence of steered and unsteered light on the physical lens.

### Claim 51 (depends on 31)

The projector of claim 31 further comprising a diffuser in an optical path of the steered light upstream of the combining rod to diffuse the steered light.

### Claim 52 (depends on 31)

The projector of claim 31 further comprising a diffuser in an optical path of the unsteered light upstream of the combining rod.

### Claim 53 (depends on 31)

The projector of claim 31 further comprising a diffuser downstream of the combining rod.

### Claim 54 (depends on 31)

The projector of claim 31 further comprising optics configured to generate base illumination to increase intensity of the steered or unsteered light.

### Claim 55 (depends on 54)

The projector of claim 54 wherein the optics configured to generate base illumination comprise a mirror positioned adjacent the phase modulator.

### Claim 56 (depends on 55)

The projector of claim 55 wherein the mirror is positioned in a plane of the two-dimensional array of pixels of the phase modulator.

### Claim 57 (depends on 55)

The projector of claim 55 wherein the mirror is parallel to the phase modulator.

### Claim 58 (depends on 55)

The projector of claim 55 wherein the mirror is adjacent to one or more edges of the phase modulator.

### Claim 59 (depends on 55)

The projector of claim 55 wherein the mirror partially covers the two-dimensional array of pixels of the phase modulator.

### Claim 60 (depends on 54)

The projector of claim 54 wherein the optics configured to generate base illumination comprise a prism configured to pull some light out of the light beams to use as base illumination.

### Claim 61 (depends on 31)

The projector of claim 31 further comprising one or more additional light sources configured to generate base illumination to increase intensity of the steered or unsteered light.

### Claim 62 (depends on 1)

The projector of claim 1 comprising a camera configured to capture images of the light steered image and connected to provide the captured images to the controller.

### Claim 63 (depends on 62)

The projector of claim 62 wherein the controller is configured to process the captured images of the light steered images to determine characteristics of light used to generate the light steered images and to vary one or more optical forms of the patch lenses to be displayed by the phase modulator.

### Claim 64 (depends on 1)

The projector of claim 1 wherein the one or more light sources comprise emitters which emit multi-colour light.

### Claim 65 (depends on 64)

The projector of claim 64 wherein the optical forms of each of the patch lenses is configured at least partially based on a wavelength of the corresponding light beam.

### Claim 66 (depends on 31)

The projector of claim 31 wherein the one or more light sources comprise emitters which emit multi-colour light, wherein the combining rod homogenizes unsteered light of different wavelengths in one or both of direction of the light and colour of the light.

### Claim 67 (depends on 66)

The projector of claim 66 wherein the optical forms of each of the patch lenses is configured at least partially based on a wavelength of the corresponding light beam.

### Claim 68 (depends on 66)

The projector of claim 66 further comprising one or more additional light sources of different wavelengths positioned to emit light into the combining rod to increase intensity of the unsteered light.