WO2020015542A1 - 光投射方法和装置 - Google Patents

光投射方法和装置 Download PDF

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Publication number
WO2020015542A1
WO2020015542A1 PCT/CN2019/094785 CN2019094785W WO2020015542A1 WO 2020015542 A1 WO2020015542 A1 WO 2020015542A1 CN 2019094785 W CN2019094785 W CN 2019094785W WO 2020015542 A1 WO2020015542 A1 WO 2020015542A1
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Prior art keywords
light
coupled
grating
waveguide device
axis direction
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PCT/CN2019/094785
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English (en)
French (fr)
Inventor
吕方璐
Original Assignee
深圳市光鉴科技有限公司
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Priority to EP19837498.5A priority Critical patent/EP3822674B1/en
Publication of WO2020015542A1 publication Critical patent/WO2020015542A1/zh

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    • 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
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G02B27/4205—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C3/00—Measuring distances in line of sight; Optical rangefinders
    • G01C3/02—Details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/08—Systems determining position data of a target for measuring distance only
    • 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
    • G02B27/0944—Diffractive optical elements, e.g. gratings, holograms
    • 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
    • G02B6/0016—Grooves, prisms, gratings, scattering particles or rough surfaces
    • 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
    • G02B6/0025—Diffusing sheet or layer; Prismatic sheet or layer
    • 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
    • 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
    • G02B6/0036—2-D arrangement of prisms, protrusions, indentations or roughened surfaces
    • 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
    • G02B6/0038—Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width 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
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B15/00—Special procedures for taking photographs; Apparatus therefor
    • G03B15/02—Illuminating scene
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/46—Indirect determination of position data
    • G01S17/48—Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4814—Constructional features, e.g. arrangements of optical elements of transmitters alone
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4818—Constructional features, e.g. arrangements of optical elements using optical fibres
    • 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
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/34—Optical coupling means utilising prism or grating

Definitions

  • the invention relates to a light projection method and device.
  • Light projection technology is essential to the function of some important devices.
  • the structured light projection technology is applied to a three-dimensional camera module of a mobile phone to identify facial features.
  • the projected light reflected by facial features can be captured by a detector and analyzed by an algorithm to "perceive" the topological structure of the face. Accordingly, the design of identity verification, emoji generation, image capture orientation, and other various functions can be performed according to the input of facial feature recognition.
  • the shortcomings of the light projection technology are high cost, large equipment size, and low integration, which has caused a bottleneck to the improvement of equipment functions based on the light projection technology. Therefore, the consumer market and related industries are looking to improve existing light projection technologies.
  • a waveguide device includes a first surface, a second surface, a fourth surface, and a layer of a light absorbing material.
  • the first surface includes a first grating structure.
  • the waveguide device is configured to: guide the coupled light beam to perform total internal reflection (total internal reflection) between the first surface and the second surface; and the first grating structure is configured to interfere with total internal reflection so that at least a portion is coupled.
  • the incoming light beam is coupled out of the waveguide device and is projected from the first surface.
  • the part of the coupled light beam coupled out of the waveguide device forms a coupled out light beam.
  • the remaining part of the coupled light beam after total internal reflection reaches the fourth surface after each first grating structure is coupled out.
  • the light absorbing material layer is parallel to the second surface and spaced from the second surface.
  • the fourth surface may include another layer of light absorbing material for absorbing the remaining portion coupled into the light beam.
  • the coupled light beam converges from the first surface to form an upright light cone, and then diverges to form an inverted light cone above the upright light cone; a section of the upright or inverted light cone parallel to the first surface includes a coupling with The dot matrix corresponding to the outgoing beam.
  • the coupled light beam diverges from the first surface to form an inverted light cone.
  • a cross section of the inverted light cone parallel to the first surface includes a lattice corresponding to the coupled light beam.
  • the first surface is in the xy plane
  • the coupled light beam propagates in the waveguide device substantially along the x-axis direction of the xy plane
  • the coupled light beam is substantially along the orthogonal to the xy plane.
  • the first grating structure is distributed in the xy plane with corresponding (x, y) positions.
  • Each first grating structure is associated with a grating depth, a duty cycle, a period, and a direction relative to the z-axis in the x-y plane.
  • the first grating structures at different positions in the x-axis direction have at least one of different grating depths and different grating duty cycles.
  • the first grating structures at different positions in the x-axis direction have different periods.
  • the first grating structures at different positions in the y-axis direction have different orientations.
  • the waveguide device is a planar waveguide
  • the first surface and the second surface are parallel to each other and are the largest surface of the planar waveguide
  • the coupled light beam is coupled out of the waveguide device from the first surface.
  • the waveguide device is a planar waveguide
  • the first surface and the second surface are parallel to each other and the largest surface of the planar waveguide
  • the first grating structure includes a first grating structure disposed between the first surface and the second surface.
  • the coupled beam is coupled out of the waveguide device from the first surface.
  • the waveguide device further includes an elongated third surface opposite the fourth surface.
  • the light source couples light into the waveguide device through the third surface to form a coupled light beam.
  • Light from the light source is collimated into a line shape corresponding to the elongated third surface.
  • a prism is provided on at least one of the first surface or the second surface, and the light source couples light into the waveguide device through the prism to form a coupled light beam.
  • the waveguide device further includes a second grating structure provided on at least one of the first surface or the second surface.
  • the light source couples light into the waveguide device through the second grating structure to form a coupled light beam.
  • the light absorbing material layer is a colored anodized aluminum layer.
  • a light projection system includes a waveguide device including a first surface, a second surface, a fourth surface, and a layer of a light absorbing material, the first surface including a first grating structure; and A light source that couples light into a waveguide device to form a coupled light beam.
  • the waveguide device is configured to guide the coupled light beam for total internal reflection between the first surface and the second surface.
  • the first grating structure is configured to interfere with total internal reflection so that at least a part of the coupled light beam is coupled out of the waveguide device and projected from the first surface, and the part coupled out of the waveguide device is coupled into the light beam to form a coupled out light beam.
  • the coupled-out light beam is configured to form a lattice on a surface on which the coupled-out light beam is projected.
  • the remaining part of the coupled light beam after total internal reflection reaches the fourth surface after each first grating structure is coupled out.
  • the fourth surface includes a first layer of light absorbing material for absorbing the remaining portion coupled into the light beam.
  • the light absorbing material layer is parallel to the second surface and spaced from the second surface.
  • the light projection system further includes a detector configured to receive reflections of the distant object from the coupled light beam at a plurality of positions to determine the plurality of positions relative to the light projection The distance of the system.
  • a waveguide device includes a first surface, a second surface, a fourth surface, and a light absorbing material layer.
  • the first surface includes a first grating structure.
  • the waveguide device is configured to guide the coupled light beam for total internal reflection between the first surface and the second surface.
  • the first grating structure is configured to interfere with total internal reflection so that at least a part of the coupled light beam is coupled out from the waveguide device and projected from the first surface, and the part coupled out of the waveguide device is coupled into the light beam to form a coupled out light beam, the coupling
  • the outgoing light beam is configured to form a lattice on a surface coupled to the projection of the outgoing light beam.
  • FIG. 1 is a schematic diagram of a light projection system according to various embodiments of the present invention.
  • FIG. 2 is a side view of an exemplary light projection system according to various embodiments of the present invention.
  • FIG. 3 is a side view of an exemplary light projection device according to various embodiments of the present invention.
  • FIGS. 4A-4I are side views of a light projection structure coupled from a light source according to various embodiments of the present invention.
  • 5A-5F are side views coupled from a light projection structure according to various embodiments of the present invention.
  • 6A is a side view of an exemplary light projection device for projecting light according to various embodiments of the present invention.
  • FIG. 6B is a schematic diagram of a grating coupling efficiency with respect to a grating depth and a duty ratio according to various embodiments of the present invention.
  • FIG. 6C is a schematic diagram of a grating coupling efficiency with respect to a grating duty ratio according to various embodiments of the present invention.
  • FIG. 7A is a perspective view of a light projection device for projecting light according to various embodiments of the present invention.
  • FIG. 7B is a schematic diagram of a lattice corresponding to the coupled light beam according to various embodiments of the present invention.
  • FIG. 8A is a perspective view of a light projection device for projecting light according to various embodiments of the present invention.
  • FIG. 8B is a schematic diagram of a coupled out beam angle with respect to a grating period according to various embodiments of the present invention.
  • FIG. 9A is a top view of an exemplary grating on a first surface according to embodiments of the present invention.
  • FIG. 9B is a schematic diagram of the angle of the coupled beam relative to the rotation angle of the grating according to various embodiments of the present invention.
  • FIG. 10 is a top view of an exemplary grating on a first surface according to embodiments of the present invention.
  • FIG. 11 is a top view of an exemplary grating on a first surface according to various embodiments of the present invention.
  • FIG. 12 is a schematic diagram of an exemplary light projection system for projecting light according to various embodiments of the present invention.
  • FIG. 13 is a schematic diagram of an exemplary light projection system for projecting light according to various embodiments of the present invention.
  • FIG. 14 is a schematic diagram of an exemplary light projection system for projecting light according to various embodiments of the present invention.
  • Light projection is a key step in applications such as 3D feature detection and 3D maps.
  • depth camera modules used in industrial part inspections and medical inspections need to measure depth information.
  • one or more light sources may project a predetermined pattern of structured light beams onto an object (for example, an object 104 such as a human face) and then detect A detector (for example, the detector 103) captures the reflected light of the light beam to measure various optical parameters.
  • the light projection system 102 and the detector 103 may be provided on the same device (for example, device 101) or on different devices.
  • the detector 103 may be part of the light projection system 102 and configured to receive reflections of the projected light beam by distant objects 104 at multiple locations to determine the multiple locations relative to light The distance of the projection system 102.
  • the light projection system 102 may be implemented on various systems or devices, such as a mobile phone, a computer, a tablet computer, a wearable device, a vehicle, and so on.
  • the extremely flat reflection plane at the object can be used as a reference, and the reflection of the projection light by the reference can be preset as the reference reflected light beam.
  • Facial features can be determined based on the difference between the detected reflected beam and the reference reflected beam, and this difference is displayed as a shift or distortion of the reference reflected beam. This method of measurement is called triangulation.
  • the light projection technology used to project the structured light beam adopts a random lattice projection method. Randomly arranging multiple lasers to obtain a random lattice will inevitably increase cost and module size and increase integration difficulty.
  • the present invention provides a light projection system and method.
  • the light source can couple the light beam into the waveguide device through one surface of the waveguide device, and then the waveguide device projects multiple light beams through a grating on the other surface to form a dispersed output light beam.
  • the light source may be a single laser (for example, an edge-emitting laser, a vertical cavity surface-emitting laser (VCSEL)), a light emitting diode, or the like, so it is not necessary to use multiple lasers as in the prior art. Since waveguide devices can be fabricated using standard lithographic techniques, manufacturing costs can be further reduced.
  • the waveguide device can be integrated on the substrate, the overall size of the light projection system can be reduced. Further, the waveguide device of the present invention benefits from zero-order interference without zero-order diffraction, because the total internal reflection constraint makes zero-order transmission impossible.
  • a waveguide device is a structure that directs waves (for example, electromagnetic (optical) waves as in the present invention) with minimal energy loss by limiting wave expansion to one or more dimensions. .
  • a light projection system includes a waveguide device, a light source, and a detector, the waveguide device includes a first surface and a second surface, the first surface includes a first grating structure, and the light source Light is coupled into a waveguide device to form a coupled beam.
  • the waveguide device is configured to guide the coupled light beam for total internal reflection between the first surface and the second surface.
  • the grating structures eg, each first grating structure
  • the detector is configured to receive reflections of the distant object from the coupled light beam at a plurality of positions to determine the distance of the plurality of positions relative to the light projection system. This determines the topological structure of the surface of the object.
  • a light projection device including a light source and a light projection structure (for example, a waveguide device) will be described in more detail with reference to FIGS. 2 and 3.
  • the light projection system may further include a projection lens structure, as shown in FIG. 2.
  • the coupled light passes through the projection lens structure to a distant object.
  • FIG. 2 is a side view of an exemplary light projection system 102 according to various embodiments of the present invention.
  • the light projection system 102 may be implemented on various systems or devices, such as a mobile phone, a computer, a tablet, a wearable device, a vehicle, and so on.
  • the exemplary light projection system 102 may include a light projection device 211 and an optional projection lens structure 231 (or referred to as a projection lens).
  • the light projection device 211 includes a light source 201 and a light projection structure 202.
  • the light source 201 includes a single laser (for example, an edge emitting laser, a vertical cavity surface emitting laser (VCSEL)), a light-emitting diode (LED) with light collimation, or the like.
  • the light source 201 may include multiple lasers or diodes (for example, an edge-emitting laser array, a VCSEL array, an LED array).
  • the light projection structure 202 may include a waveguide device described in detail below. The light coupled from the light projection structure 202 may be perpendicular to the surface, focused or defocused.
  • a light beam (coupled light beam) emitted from the light projection device 211 may be coupled out from one surface of the light projection device 211.
  • the light beam can be projected into space through the projection lens structure 231.
  • the projection lens structure 231 (for example, one or more lenses) may be provided above the waveguide device (for example, above the first surface of the waveguide device described later).
  • the projection lens structure 231 may be configured to receive the coupled light beam and project the coupled light beam onto a distant object in the environment. Alternatively, the light beam is directly projected into the space from the light projection device 211.
  • the projection lens structure 231 may include various lenses or lens combinations (for example, one to six separate lenses) for controlling the direction of the projected light beam.
  • the projection lens structure 231 can be configured to increase or decrease the field of view of the projection beam array.
  • the projection lens structure 231 may increase the field of view by dispersing the projection beam array, or reduce the field of view by converging the projection beam array.
  • the projection lens structure 231 may be configured to collimate each coupled light beam.
  • the laser beam waist of the projection beam array collimated by the projection lens structure 231 ranges from 10 mm to 1 m.
  • the projection lens structure 231 can collimate the output light to form a clear image (for example, a dot matrix) at an observed distance (for example, within a range of 10 cm to 10 m according to the application).
  • FIG. 3 is a side view of an exemplary light projection device 211 according to various embodiments of the present invention. The structure and operation shown in FIG. 3 and described below are exemplary.
  • the light source 201 emits light, and optically couples the light into the light projection structure 202 on a surface coupled into (couples the light into the light projection structure 202) region.
  • the coupling-in arrangement includes end-face coupling, grating coupling, prism coupling, or the like. After entering the light projection structure 202, light is totally internally reflected between the first surface and the second surface within the light projection structure 202.
  • the light projection structure 202 may be made of a material having a high refractive index (for example, Plexiglas, quartz glass, single crystal silicon, and fused silica). In one example, if quartz glass with a refractive index of 1.45 is used, the critical angle of total internal refraction is 44 °.
  • Light propagating in the light projection structure 202 may be coupled out of the light projection structure 202 at various coupling-out regions (eg, on a first surface).
  • the coupling-out region may be a region having a coupling-out structure (eg, a transmission grating, a reflection grating, a reflector).
  • the light projection structure 202 includes a first surface and a second surface. At least one of the first surface or the second surface includes a first grating structure.
  • a grating structure may refer to a grid (for example, an optical grid), which is a combination of parallel, identically elongated elements arranged at regular intervals.
  • the outline of a ridge grating is shown, and each ridge grating may include a plurality of identical, parallel elongated ridges (see grating A of FIG. 7A).
  • the light projection structure guides the coupled light beam to perform total internal reflection between the first surface and the second surface.
  • Each first grating structure interferes with total internal reflection so that at least a part of the coupled light beam is coupled out of the light projection structure, and the part of the coupled light beam coupled out of the light projection structure is a coupled out light beam.
  • one coupled light beam propagating in the waveguide device can be coupled out of the waveguide device through a grating to obtain a plurality of coupled out light beams.
  • FIGS. 4A-4I are side views of coupling from a light source into a light projection structure (eg, a planar waveguide) according to various embodiments of the present invention.
  • a light projection structure eg, a planar waveguide
  • the structures and operations shown in FIGS. 4A-4I and described below are exemplary.
  • the light source 201 can emit light substantially in a horizontal plane, and the coupled light can propagate substantially in a vertical plane.
  • FIG. 4B, FIG. 4C, FIG. 4D, and FIG. 4E the light source 201 can emit light substantially in a vertical plane, and the coupled light can basically propagate in the vertical plane.
  • the horizontal plane and the vertical plane are opposite, and do not constitute a limitation on the environment.
  • light emitted by the light source 201 may be coupled into the light projection structure 202 through one surface of the light projection structure 202 using “end-face coupling”.
  • the ambient refractive index of the coupled light, the refractive index, wavelength of the light projection structure 202, and the incident angle of the coupled light on the third surface of the light projection structure 202 satisfy the "end-face coupling" condition as understood by those skilled in the art.
  • light is totally internally reflected between the first surface and the second surface of the light projection structure 202, and is coupled out from the first surface of the light projection structure 202.
  • a lens may be used to focus the light from the light source 201 into the light projection structure 202 through "end coupling".
  • the light emitted by the light source 201 may be coupled into the light projection structure 202 by coupling into a grating using “grating coupling”. That is, the light projection structure further includes a second grating structure provided on at least one of the first surface or the second surface. The light source couples light into the light projection structure through the second grating structure to form a coupled light beam. As shown in FIG. 4B, the coupled grating can be fabricated on the first surface of the light projection structure 202. Although the figure shows that the coupled grating is flush with the first surface, it can also be made higher or lower than the first surface as long as the subsequent total internal reflection is maintained.
  • the refractive index of the environment coupled into the light, the refractive index of the light projection structure 202, the geometry of the coupled grating, the wavelength, and the angle of incidence of the coupled light on the third surface of the light projection structure 202 satisfy the "understanding by those skilled in the art" Grating Coupling "condition.
  • the light projection structure 202 light is totally internally reflected between the first surface and the second surface of the light projection structure 202, and is coupled out from the first surface of the light projection structure 202.
  • FIG. 4C is similar to FIG. 4B, except that the coupling-in grating can be fabricated on the second surface of the light projection structure 202.
  • the light emitted by the light source 201 may be coupled into the light projection structure 202 through a prism using “prism coupling”. That is, the light projection structure may further include a prism provided on at least one of the first surface, the second surface, or the third surface.
  • the light source couples light into the light projection structure through a prism to form a coupled light beam.
  • "provided on ... (an object)” also includes “close to ... (the object) setting”. Any gap between the prism and the light projection structure 202 may be filled with optical glue or another index matching material.
  • the prism may be disposed on a third surface of the light projection structure 202.
  • the light source 201 may be disposed on the edge of the second surface to emit light into the prism. Light is reflected once inside the prism and is coupled from the prism into the light projection structure 202 on the third surface.
  • the refractive index of the prism, the refractive index of the light projection structure 202, the geometry of the prism, and the angle of incidence of the light from the light source 201 satisfy the "grating coupling" condition as understood by those skilled in the art.
  • light projection structure 202 light is totally internally reflected between the first surface and the second surface of the light projection structure 202, and is coupled out from the first surface of the light projection structure 202.
  • 4E is similar to FIG. 4D, except that the prism can be turned upside down so that the light source 201 is disposed on the first surface edge.
  • the prism may be disposed on the first surface of the light projection structure 202.
  • the light emitted from the light source 201 may enter the prism.
  • an evanescent mode of light may be coupled into the light projection structure 202.
  • the refractive index of the prism, the refractive index of the light projection structure 202, the geometry of the prism, and the angle of incidence of the light from the light source 201 satisfy the "phase matching" condition as understood by those skilled in the art.
  • light is totally internally reflected between the first surface and the second surface of the light projection structure 202, and is coupled out from the first surface of the light projection structure 202.
  • FIG. 4G is similar to FIG. 4D, except that the prism may be disposed on the second surface of the light projection structure 202.
  • FIG. 4H is similar to FIG. 4D, except that the prism is disposed on the first surface, light is reflected once on the slope inside the prism, and then coupled into the light projection structure 202.
  • FIG. 4I is similar to FIG. 4H, except that a prism is provided on the second surface.
  • the prisms used in FIGS. 4F and 4G may be regular prisms, and the prisms used in FIGS. 4H and 4I may be wedge-shaped prisms.
  • FIGS. 5A-5F are side views of a light projection structure (for example, a planar waveguide) coupled out according to various embodiments of the present invention.
  • the structures and operations shown in FIGS. 5A-5F and described below are exemplary. For simplicity, FIGS. 5A-5F omit coupling and propagation of light in the light projection structure 202.
  • the light projection structure includes a planar waveguide.
  • the first surface and the second surface are parallel to each other and are the largest surfaces of the planar waveguide.
  • the coupled out light beam is coupled from the first surface from the light projection structure.
  • a first grating structure is included in the first surface or the second surface.
  • the light projection structure may further include a metal layer provided on the second surface.
  • the first grating structure includes a volume grating provided between the first surface and the second surface. That is, the coupled light beam is totally internally reflected in the light projection structure 202.
  • the illustrated waveguide device structure includes a grating, which may allow one or more diffraction orders to be coupled out of the waveguide device.
  • a grating can be fabricated on each coupled-out region on the first surface of the light projection structure 202.
  • the coupling-out regions correspond to the respective total internal reflection regions.
  • the diffraction grating may be fabricated in each coupling-out region on the second surface of the light projection structure 202. That is, the waveguide device includes: (1) a bottom layer on which a grating is fabricated, the bottom layer having a first refractive index; and (2) a top layer having a shape complementary to the bottom layer.
  • the coupling-out region may correspond to each total internal reflection region, and a part of the light irradiated on each coupling-out region may be redirected to the first surface, and then coupled out from the waveguide from the first surface.
  • Figure 5B also shows the configuration 2 where the grating is fabricated on the second surface.
  • the refractive index of the grating may be the same as or different from that of the waveguide device.
  • the microlens array may be disposed on the first surface corresponding to the position of the coupling-out area in FIG. 5B, so that the coupling-out light can be collimated, made parallel, or otherwise controlled. .
  • a refractive grating may be fabricated in each coupled-out region on the first surface of the light projection structure 202.
  • a triangular-shaped grating shown in the figure may be etched from the first surface.
  • the grating corresponds to a coupling-out region, and a part of the total internal reflection light can be coupled out of the waveguide device from the waveguide device.
  • reflective gratings can be fabricated on each of the coupled-out regions on the second surface of the light projection structure 202.
  • a triangular-shaped grating shown in the figure may be etched from the second surface.
  • the grating corresponds to a coupling-out region, and a part of the total internal reflection light may be reflected from the grating to the first surface and then coupled out of the waveguide device.
  • a volume grating can be fabricated within a waveguide device.
  • the periodicity of a volume grating is an alternating refractive index between repeating periodic sections.
  • the refractive index change interface corresponds to a coupling-out region, and a part of the total internal reflection light can be reflected from the interface to the first surface and then coupled out of the waveguide device.
  • the coupling-out efficiency can be determined by the grating depth (also called “thickness") and the grating duty cycle ( Figures 6A-6C), and the angle of the coupled-out beam relative to the surface normal can be determined by the grating period ( Figure 8A- Figure 8B) It is determined that the rotation angle of the coupled beam can be determined by the grating orientation (FIG. 9A-9B).
  • the grating (first grating structure) interferes with total internal reflection so that the coupled-out beam is projected from the first surface, and the coupled-out beam is configured such that a point is formed on the surface where the coupled-out beam is projected Array.
  • the coupled out light beam may form a lattice on a plane parallel to the first surface.
  • the coupled light beam propagates perpendicular to the first surface, and a cross-section of the coupled light beam parallel to the first surface includes a random lattice corresponding to the coupled light beam.
  • the coupled light beam diverges from the first surface to form an inverted light cone.
  • a cross section of the inverted light cone parallel to the first surface includes a random lattice corresponding to the coupled light beam (FIG. 7B).
  • the coupled light beam converges from the first surface to form an upright light cone, and then diverges to form an inverted light cone above the upright light cone;
  • a cross-section of the upright or inverted light cone parallel to the first surface includes the coupled out light beam Corresponding dot matrix.
  • the dot pattern is not limited to the illustrated example, and may include various other configurations. The following description with reference to FIGS. 6A to 9B may borrow the coordinate system shown in FIG. 10 or FIG. 11.
  • the first surface (or the second surface) of the waveguide device is in a xy plane in which the x-axis direction and the y-axis direction are perpendicular to each other, and the coupled light beam is projected on the light along the x-axis direction of the xy plane. Propagating within the structure, the coupled beam propagates substantially along the z-axis direction orthogonal to the xy plane.
  • the grating structures can be randomly distributed in the x-y plane with corresponding (x, y) positions.
  • the size of the grating is about 2 ⁇ m to 30 ⁇ m
  • the number of gratings on the waveguide device is about several hundreds to one million
  • the average grating pitch is about 5 ⁇ m to 100 ⁇ m .
  • FIG. 6A is a side view of an exemplary light projection system 211 according to various embodiments of the present invention.
  • the structure and operation shown in FIG. 6A and described below are exemplary.
  • FIG. 6A may correspond to FIG. 5A described above, and the grating coupling-out mechanism is described below.
  • the direction of the coupled out beam may follow the formula:
  • ⁇ is the wavelength
  • ⁇ is the grating period
  • n is the refractive index of the waveguide device
  • ⁇ m is the angle between the coupled beam and the first surface normal
  • ⁇ i is performed in the waveguide device The angle between the total internally reflected beam and the normal to the first surface.
  • the grating period can be obtained by the following formula (labeled "period" in the figure):
  • FIG. 6B is a schematic diagram of a simulation result of the coupling efficiency changing with the grating depth and the duty ratio according to various embodiments of the present invention.
  • the grating is of a size that produces high coupling efficiency, which is the percentage (part) of the light that is totally internally coupled out of the waveguide device at the grating. Therefore, in this context, coupling efficiency can be understood as coupling out efficiency.
  • the coupling efficiency is determined by the grating depth and the duty cycle (the percentage of the ridge structure in each period). 6A and 9A with reference to the "ridge width" and “period”, divide the ridge width by the period to obtain the duty cycle. The duty cycle is also called the fill factor.
  • FIG. 6B shows the simulated coupling efficiency of two different waveguide modes (ie, TE mode and TM mode light propagation in the waveguide device).
  • the x-axis represents the duty cycle and the y-axis represents the grating depth.
  • Brighter areas represent higher coupling efficiency.
  • the highest coupling efficiency is 9.8%, which occurs at a duty cycle of 0.43 and a thickness of 0.35 ⁇ m.
  • the highest coupling efficiency is 2.8%, which occurs at a duty cycle of 0.52 and a thickness of 0.3 ⁇ m. Therefore, various coupling efficiencies can be obtained by designing the grating depth and duty cycle. Further, by adjusting the grating depth, a coupling efficiency greater than the 9.8% efficiency can be obtained.
  • the coupling efficiency relative to the duty cycle can be obtained, as shown in FIG. 6C Show.
  • the duty ratio is 0.43 and the thickness is 0.35 ⁇ m, it has the same peak coupling efficiency of 9.8%.
  • the grating may be designed so that the coupling efficiency increases as the distance from the grating to the light source 201 increases. For example, returning to FIG. 6A again, by adjusting the duty ratio and the grating depth, the coupling efficiency of the grating Y can be made larger than that of the grating X to ensure that the coupled light from the grating Y and the grating X has the same or similar power.
  • each of the grating structures is associated with a coupling-out efficiency.
  • the coupling-out efficiency increases monotonically along the x-axis direction.
  • Coupling efficiency depends on the grating depth and duty cycle of the grating structure. At least one of the grating depth or the duty cycle of the grating period is changed in the x-axis direction, so that the coupling-out efficiency monotonously increases along the x-axis direction.
  • the grating depth of the grating structure monotonically increases in the x-axis direction, so that the coupling-out efficiency monotonously increases along the x-axis direction.
  • the duty ratio of the grating structure monotonically increases in the x-axis direction, so that the coupling-out efficiency monotonously increases along the x-axis direction.
  • the x-y plane includes a plurality of regions corresponding to various position ranges along the x-axis direction, the regions including a first region and a second region. The first region is closest to the region where the light beam is coupled into the light projection structure. The second region is furthest from the region where the light beam is coupled into the light projection structure.
  • Grating structures in the same area have the same or similar coupling-out efficiency. The coupling-out efficiency increases monotonically along the x-axis direction so that the power of the coupled beam from each grating structure in the first region is the same as or similar to the power of the coupled beam from each grating structure in the second region.
  • FIG. 7A is a perspective view of a light projection device 211 according to various embodiments of the present invention.
  • the structure and operation shown in FIG. 7A and described below are exemplary.
  • the light projection structure 202 includes a planar waveguide having a grating fabricated on a first surface.
  • the light projection structure 202 shown in FIG. 7A is similar to the light projection structure 202 shown in FIG. 6A, except that the coupled light beam in FIG. 7A is perpendicular to the first surface.
  • the light source 201 includes one or more lasers or LEDs with light collimation. The lasers or LEDs may be arranged in a row in a side surface of the planar waveguide.
  • a grating (eg, grating A, grating B, grating C, grating D, etc.) may be made at a random position on the first surface.
  • the gratings may have the same grating period.
  • Each coupled out beam is coupled out of each waveguide from the waveguide device. Therefore, when viewed from the top, the coupled beams can form a random lattice, as shown in Figure 7B.
  • the dot pattern shown is exemplary only. Based on the configuration of the grating structure (for example, by adjusting the period, direction, depth, duty cycle, (x, y, z) position, number, etc. on the waveguide device), any dot pattern can be obtained to meet application requirements.
  • FIG. 8A is a perspective view of a light projection device 211 according to various embodiments of the present invention.
  • the structure and operation shown in FIG. 8A and described below are exemplary.
  • the light projection device 211 is similar to FIG. 7A and FIG. 8A, and also provides a random lattice, except that the gratings in FIG. 8A may have different grating periods.
  • the gratings eg, grating E, grating F, grating G, grating H, etc.
  • the gratings may have different grating periods ⁇ .
  • ⁇ m changes by the grating period ⁇ . That is, the coupled out light beam can propagate at different angles from the orthogonal direction. Therefore, the variation of ⁇ m also increases the randomness of the lattice.
  • Figure 8B shows a plot of the coupled out beam angle (in the xz plane relative to the z-axis direction) versus the grating period.
  • the angle between the coupled beam and the orthogonal direction can be controlled by changing the grating period in the same vertical plane that is perpendicular to the first surface and along the direction (x-axis direction) in which the light propagates in the waveguide device. Between -5 ° and 15 °.
  • the coupled-out beam may also have a component in the y-axis direction
  • FIGS. 8A and 8B focus on the component in the x-axis direction.
  • each grating structure is associated with a period.
  • the period will vary.
  • the change in period causes the coupled out beam to be coupled out of the waveguide device with a range of angular deviation in the x-axis direction.
  • the period monotonically increases along the x-axis direction.
  • the monotonic change of the period along the x-axis direction causes the coupled-out beam to be coupled out of the light projection structure with an angular deviation range in the x-axis direction.
  • the grating may have various directions in the x-y plane.
  • the direction of the grating can be reflected by referring to the direction of the grating ridge.
  • the grating M may be arranged so that its ridges are perpendicular to the x-axis direction
  • the grating N may be arranged so that its ridges are at a positive rotation angle with the x-axis direction
  • the grating K may be arranged so that its ridges are negative with the x-axis direction. Rotation angle.
  • the coupled-in light travels from left to right within the waveguide device in the x-axis direction.
  • the component of the light coupled from the grating M in the y-axis direction is zero. That is, the component in the x-axis direction is ignored, and the light coupled from the grating M propagates in the z-axis direction.
  • the light coupled from the grating N with a positive rotation angle has a negative y-axis component. That is, the component in the x-axis direction is ignored, and the light coupled out from the grating N is propagated in the z-axis direction-the y-axis negative direction.
  • the light coupled out of the grating K from the negative rotation angle has a positive y-axis component.
  • FIG. 9A is a simplified schematic diagram of controlling the direction of the grating described in FIG. 10 below to obtain a converged coupled out beam.
  • Figure 11 below shows the inversion of Figure 9B to obtain a divergent coupled out beam.
  • FIG. 9B shows a graph of the coupled-out beam angle (in the y-z plane with respect to the z-axis direction) versus the grating rotation angle (with respect to the x-axis direction).
  • the angle of the coupled out beam can be controlled between about -70 ° and 70 ° with respect to the reference direction.
  • FIG. 9B is merely exemplary, and an alternative directional reference frame may be used.
  • the coupled-out beam may also have a component in the x-axis direction
  • FIGS. 9A and 9B focus on the component in the y-axis direction.
  • each grating structure is associated with a rotation angle with respect to the z-axis direction, and for a grating structure along the y-axis direction, the rotation angle may vary.
  • the change in the rotation angle causes the coupled beam to be coupled out of the waveguide device in an angular deviation range in a y-axis direction.
  • the rotation angle changes monotonically clockwise or counterclockwise. The monotonic change of the rotation angle causes the coupled out beam to propagate with different y-axis direction components.
  • FIGS. 10 and 11 are top views of an exemplary grating (first grating structure) on a first surface according to various embodiments of the present invention.
  • the grating may be fabricated on the second surface or according to another configuration shown in FIGS. 5A-5F.
  • the structures and operations shown in FIGS. 10 and 11 and described below are exemplary.
  • the gratings in FIG. 10 and FIG. 11 can be combined with the following cases described in FIGS. 6A-9B: the coupling out efficiency is controlled by the grating depth and the duty cycle, and the angle and the passage of the coupled beam with respect to the normal are controlled by the grating period
  • the grating direction controls the rotation angle of the coupled light beam. As shown in FIGS.
  • the planar waveguide is in the x-y plane, and the z-axis direction is a surface orthogonal direction (perpendicular to the x-y plane).
  • the definitions of the x-axis direction and the y-axis direction are as shown in this figure.
  • the z-axis direction is perpendicular to the x-y plane and points outside the paper plane.
  • the x-axis, y-axis, and z-axis directions are also called x-axis, y-axis, and z-axis positive directions, and the relative directions are called x-axis, y-axis, and z-axis negative directions.
  • the coupled light can enter the waveguide device from the left side, and part of the light is coupled out of the waveguide device through the grating, and some residual light (also known as the remaining light) remains and continues to propagate in the x-axis direction. Coupling into the light can be generated from one or more lasers.
  • the first grating structure is associated with a grating depth, a duty cycle, a period, and a direction in the x-y plane with respect to the z-axis direction.
  • the first grating structure at different positions in the x-axis direction has at least one different grating depth or different grating duty cycle.
  • the first grating structures at different positions in the x-axis direction have different periods.
  • the first grating structures at different positions in the y-axis direction have different directions.
  • the waveguide device further includes an elongated third surface opposite the fourth surface.
  • the position of the third surface relative to the first and second surfaces is as described above.
  • the light source couples light into the waveguide device through the third surface (in the light incident direction described in FIGS. 10 and 11) to form a coupled light beam.
  • Light from the light source is collimated into a line shape corresponding to the elongated third surface.
  • the laser output beam can be collimated into a linear shape by a collimating lens or an array of collimating lenses, the linear light being on the third surface of the planar waveguide and then coupled into the planar waveguide through the third surface Inside.
  • the divergence of the coupled out beam can be controlled by the grating direction and the grating period.
  • the divergence of the coupled beam in the y-axis direction can be controlled by the grating direction
  • the divergence of the coupled beam in the x-axis direction can also be controlled by the grating period.
  • the angle of the coupled-out light beam in the y-z plane (a plane including the y-axis and the z-axis) with respect to the z-axis direction changes with the rotation direction of the grating.
  • the angle of the coupled-out light beam with respect to the z-axis direction in the x-z plane varies with the grating period.
  • the output angle of the coupled-out beam increases with the grating period.
  • a convergent coupled-out beam for example, tapered and converged from the first surface
  • a divergent coupled-out beam for example, inverted cone-shaped from the first surface
  • FIG. 10 illustrates exemplary grating direction and period control for obtaining a converged coupled out beam
  • FIG. 11 illustrates exemplary grating direction and period control for obtaining a divergent coupled out beam.
  • FIGS. 10 and 11 show exemplary grating structures with grating direction control.
  • the grating direction may be changed from bottom to top in the y-axis direction so that the grating rotates clockwise with respect to the normal of the first surface. That is, in FIG.
  • the grating in the horizontal section of the first surface has no rotation, the grating in the horizontal section at the bottom of the first surface rotates negatively (sloping to the left), and the horizontal section at the top of the first surface
  • the positively rotated (inclined to the right) of the grating is such that the coupled beam of the uppermost grating has the largest negative y-axis component, and the coupled beam of the lowermost grating has the largest positive y-axis component, which is consistent with FIG. 9B and its description.
  • the direction of the grating structure in the y-axis direction can be rotated clockwise so that the coupled out light beams are condensed from the first surface in the y-z plane.
  • the grating direction may be changed from bottom to top in the y-axis direction, so that the grating rotates counterclockwise with respect to the normal of the first surface. That is, in FIG. 11, assuming that the y-axis direction is the reference direction, the grating in the horizontal section of the first surface has no rotation, the grating in the horizontal section at the bottom of the first surface rotates forward (inclined to the right), and the horizontal section at the top of the first surface.
  • the negative rotation of the grating causes the coupled beam of the uppermost grating to have the largest positive component of the y-axis, and the coupled beam of the lowermost grating has the largest negative component of the y-axis, which is consistent with FIG. 9B and its description. That is, the direction of the grating structure in the y-axis direction is rotated counterclockwise, so that the coupled out light beam is diverged from the first surface in the y-z plane. In this way, changing the direction of the grating (e.g.
  • FIGS. 10 and 11 also show exemplary grating structures with grating period control.
  • the grating period is reduced in the x-axis direction, so that the first coupled-out beam in the x-axis direction has the largest positive x-axis component, and the last coupled-out beam in the x-axis direction has the largest x-axis negative.
  • the directional component is consistent with FIG. 8B and its description. In this way, the coupled out beams converge in the x-axis direction.
  • the grating period is increased in the x-axis direction, so that the first coupled beam (coupled from the first grating) in the x-axis direction has the largest negative x-axis component and the last in the x-axis direction.
  • One coupled-out beam (coupled from the last grating) has a maximum positive x-axis component, which is consistent with FIG. 8B and its description.
  • changing the grating period eg, monotonically increasing or decreasing in the x-axis direction
  • the period can be monotonically decreasing in the x-axis direction so that the coupled out beams converge from the first surface in the x-z plane.
  • the period can be monotonically increased in the x-axis direction so that the coupled out beam is emitted from the first surface in the x-z plane.
  • the field of view in the x-axis direction converges
  • the divergence causes the coupled out light beams to converge and diverge, respectively.
  • the grating period is reduced in the x-axis direction (for example, monotonically decreasing) in combination with the grating direction being rotated clockwise in the y-axis direction (for example, a grating in the y-axis direction is monotonically rotated clockwise relative to the z-axis direction )
  • the period monotonically decreases in the x-axis direction, and at the same time rotates clockwise in the direction of the grating structure in the y-axis direction, so that the coupled out beams can be converged from the first surface.
  • the converging light beam may form an upright light cone, which is projected from the first surface and converges to a point above the first surface, but once it passes through the converging point, the light beam diverges and converges on the upright light cone.
  • the top forms an inverted light cone.
  • the grating period is increased in the x-axis direction (for example, monotonically increasing) in combination with the grating direction being rotated counterclockwise in the y-axis direction (for example, the grating in the y-axis direction is monotonically rotated counterclockwise relative to the z-axis direction)
  • the coupled out light beam can be made to diverge from the first surface. That is, the period monotonically increases in the x-axis direction, and at the same time rotates counterclockwise in the direction of the grating structure in the y-axis direction, so that the coupled out beam can be diverged from the first surface.
  • the divergent light beam may form an inverted light cone that projects from the first surface and diverges from the first surface.
  • the optical power in the waveguide device decreases along the propagation direction (x-axis directions in FIG. 10 and FIG. 11), so the power of the total internally reflected beam emitted on the grating for coupling out follows the propagation direction Decrease.
  • the coupling out efficiency can be increased along the propagation direction to compensate for the power loss. Coupling efficiency can increase monotonically in the direction of propagation.
  • the coupling-out efficiency can be changed by changing the grating depth and / or the grating duty cycle (see, as discussed above in Figures 6B and 6C). Arbitrary coupling out efficiency can be obtained with the proper combination of grating depth and grating duty cycle.
  • Grating thickness can be monotonically increased or not monotonically increased along the propagation direction.
  • Grating duty cycle can be monotonically increasing or not monotonically increasing along the propagation direction.
  • Each grating thickness and grating duty cycle need not follow any monotonic trend in the propagation direction, as long as the combination of the grating thickness and the grating duty cycle can increase the coupling-out efficiency along the propagation direction for the coupled out beam.
  • the first surface may be designed as strip-shaped total internal reflection regions (total internal reflection TIR 1 region, TIR 2 region, etc.), and these strip-shaped total internal reflection regions have corresponding the coupling efficiency ⁇ 1, ⁇ 2, ..., ⁇ n, from ⁇ 1 to ⁇ n is gradually increased so that the output power is kept constant.
  • the distribution of grating positions on the first surface in the figure. Figures 10 and 11 may be random. That is, although following the grating period, grating depth, grating duty ratio, and grating direction trends, if the first surface (or the second surface) is in the xy plane, the grating may be relative to the corresponding (x, y) position. Randomly distributed in the xy plane.
  • the random distribution means that the grating may not be fixed at a periodic position (for example, a two-dimensional lattice position, an equally spaced position, etc.) on the first or second surface.
  • the random lattice described herein corresponds to this random distribution of grating positions.
  • the random distribution of the raster positions can minimize algorithm errors.
  • Algorithm errors are not good for detection based on coupled out beams. Algorithmic errors are usually caused by periodic or other non-random graphic trends, because the algorithms that the detector runs to detect differences between reflections of beams of different structures sometimes look the same, making it difficult to distinguish one part of the graph from another .
  • each grating may include any number of convex ridges or another alternative grating structure (e.g., ribs, buried ridges, and diffused ridges). (diffused ridge)).
  • the contours of the ridges can be square, circular, triangular, and the like.
  • FIG. 10 and FIG. 11 are square, the shape of each grating may be circular, oval, rectangular, or the like.
  • the size of the grating can be from one period (about 1 ⁇ m) to the entire pixel size (about 30 ⁇ m).
  • the spot size will increase with the size of the grating, and the ideal spot size (beam size of the projected beam) can be obtained by controlling the size of the grating. For example, if an application requires more light spots, the size of the grating can be reduced to focus more light spots on a fixed area (eg, the first surface). If an application requires brighter light spots (higher signal-to-noise ratio), the size of the grating can be increased, because larger light spots have more power and are therefore brighter.
  • FIG. 12 is a schematic diagram of an exemplary light projection system 102 according to various embodiments of the present invention.
  • the light projection system 102 may implement the coupling-in mechanism described above with reference to FIG. 4H and the coupling-out mechanism described above with reference to FIG. 5B (configuration 2).
  • the waveguide device further includes a reflective layer provided on the second surface and covering the grating structure.
  • the reflective layer includes one or more metal (alloy) and / or non-metal (e.g., dielectric) sublayers.
  • the reflective layer includes one or more sub-layers, each sub-layer including at least one of the following: aluminum, silver, gold, copper, titanium, chromium, nickel, germanium, indium, tin, platinum, palladium, zinc, oxide Aluminum, silver oxide, gold oxide, copper oxide, titanium oxide, chromium oxide, nickel oxide, germanium oxide, indium oxide, tin oxide, platinum oxide, palladium oxide, zinc oxide, aluminum nitride, silver nitride, gold nitride, Copper nitride, titanium nitride, chromium nitride, nickel nitride, germanium nitride, indium nitride, tin nitride, platinum nitrid
  • a reflective layer eg, a metal layer or a highly reflective coating
  • the metal can be aluminum, silver, gold, copper or another highly reflective metal.
  • FIG. 13 is a schematic diagram of an exemplary light projection system 102 according to various embodiments of the present invention.
  • the light projection system 102 may implement the coupling-in mechanism described above with reference to FIG. 4H and the coupling-out mechanism described above with reference to FIG. 3.
  • the illustrated layer of light absorbing material can be used to minimize background noise from leaky light or incompletely coupled residual light in higher grating modes.
  • a layer of light absorbing material (at the end of light propagation in the waveguide device) can be provided directly on the side wall of the waveguide device.
  • the light-absorbing material layer can be set to have a gap with the second surface to prevent damaging the total internal reflection condition.
  • the light-absorbing material layer may be a (colored) anodized aluminum layer, a roughened surface, a carbon black coating, or another layer of light-absorbing material.
  • the light projection structure further includes a fourth surface, a first light absorbing material layer, and a second light absorbing material layer.
  • the remaining part of the coupled beam after total internal reflection reaches the fourth surface after each grating structure is coupled out.
  • the fourth surface includes a layer of light absorbing material for absorbing the remaining portion coupled into the light beam.
  • the second light absorbing material layer is parallel to the second surface and spaced from the second surface.
  • the second light absorbing material layer can absorb light leaking out of the waveguide device from the second surface. The gap prevents absorption of coupled light that is still propagating within the waveguide device.
  • FIG. 14 is a schematic diagram of an exemplary light projection system 102 according to various embodiments of the present invention.
  • the light projection system 102 may implement the coupling-in mechanism described above with reference to FIG. 4H and the coupling-out mechanism described above with reference to FIG. 3.
  • a residual light coupling out setting may be added to couple the residual light from the waveguide device through the above-mentioned end-face coupling, grating coupling, or prism coupling (the end of light propagation in the waveguide device Place).
  • Detectors such as a photodiode for detection (for example, silicon, germanium, or another diode) can be used to detect the coupled residual light.
  • any accident for example, chip cracking, water damage, vapor damage, laser dislocation, coupling into prism misalignment, or another failure event
  • the failure point The conditions of total internal reflection will be destroyed.
  • the event of residual light change can be detected in time by detecting the photodiode, and the input laser is turned off accordingly to ensure eye safety. If the input laser is not turned off, some laser beams will leak from the light projection system. Because the power of these beams is not controlled, it can cause eye damage.
  • the words "or”, “or” may be interpreted in an inclusive or exclusive meaning.
  • multiple examples can be used as a single example for the resources, operations, or structures described therein.
  • the boundaries between different resources, operations, engines, and data saves are arbitrary, and specific operations are described in the context of a specific illustrative configuration. Other configurations of functions are also contemplated and fall within the scope of various embodiments of the invention.
  • the structures and functions presented as independent resources in the exemplary configuration may be implemented as combined structures or resources to implement the application.
  • structures and functions presented as a single resource can be implemented as separate resources to implement an application.
  • conditional words such as, in particular, “may,” “may,” “may,” or “may” or other terms used herein as understood, are generally intended to convey that certain embodiments include a certain These features, elements and / or steps are not included in other embodiments. Thus, such conditional words generally do not indicate that the features, elements, and / or steps must be used in any way for one or more embodiments, or that one or more embodiments must include determining these features, elements, and / or Whether the steps are to be incorporated or whether the logic is implemented in any particular embodiment, with or without user input or prompts.

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Abstract

一种包括第一表面和第二表面的波导器件。第一表面包括第一光栅结构。波导器件构造为引导耦合入光束在第一表面和第二表面之间进行全内反射。第一光栅结构构造为干扰全内反射以使得至少部分耦合入光束从波导器件耦合出来并从第一表面投射出去，从波导器件耦合出的这部分耦合入光束形成耦合出光束，耦合出光束配置为在耦合出光束投射的表面上形成点阵。

Description

光投射方法和装置 技术领域
本发明涉及光投射方法和装置。
背景技术
光投射技术对实现一些重要设备的功能至关重要。例如，结构光投射技术应用于手机的三维相机模组中，用于识别面部特征。面部特征反射的投射光可由检测器捕获，并通过算法进行分析，以“感知”面部的拓扑结构。相应地，可根据面部特征识别的输入进行身份验证、表情符号生成、图像采集定位(image capture orientation)和其它各种功能的设计。
目前，光投射技术的缺点在于成本高、设备尺寸大以及集成度低，这对建立于光投射技术的设备功能的改进造成了瓶颈。因此，消费者市场和相关行业都希望能改进现有光投射技术。
发明内容
本发明的各个实施例包括光投射结构(例如，波导器件(waveguide))、装置和系统。根据本发明的一个方面，波导器件包括第一表面、第二表面、第四表面和光吸收材料层。所述第一表面包括第一光栅结构。所述波导器件构造为：引导耦合入的光束在第一表面和第二表面之间进行全内反射(total internal reflection)；所述第一光栅结构构造为：干扰全内反射以使至少一部分耦合入的光束耦合出波导器件并且从第一表面投射出去，从波导器件耦合出的这部分耦合进的光束形成耦合出光束。耦合入的光束经全内反射后的其余部分在各第一光栅结构耦合出后到达第四表面。所述光吸收材料层与第二表面平行且与第二表面有间隔。所述第四表面可以包括另一光吸收材料层，用于吸收耦合入光束的其余部分。
在一些实施例中，耦合出的光束从第一表面会聚，形成直立光锥，然后发散，在直立光锥的上方形成倒立光锥；直立或倒立光锥与第一表面平行的截面包括与耦合出的光束对应的点阵。
在一些实施例中，耦合出的光束从第一表面发散，形成倒立光锥，倒立光锥与第一表面平行的截面包括与耦合出的光束对应的点阵。
在一些实施例中，所述第一表面在x-y平面内，耦合入的光束基本上沿着x-y平面的x轴方向在波导器件内传播，耦合出的光束基本上沿着与x-y平面正交的z轴方向传播，第一光栅结构以相应的(x，y)位置分布在x-y平面内。各第一光栅结构与光栅深度、占空比、周期和在x-y平面内相对于z轴的方向相关联。在x轴方向上不同位置的第一光栅结构具有不同的光栅深度和不同的光栅占空比的至少其中之一。在x轴方向上不同位置的第一光栅结构具有不同的周期。在y轴方向上不同位置的第一光栅结构具有不同的方向(orientations)。
在一些实施例中，所述波导器件为平面波导，第一表面与第二表面相互平行且为平面波导的最大表面，耦合出的光束自第一表面从波导器件中耦合出来。
在一些实施例中，所述波导器件为平面波导，第一表面与第二表面相互平行且为平面波导的最大表面，所述第一光栅结构包括设在第一表面和第二表面之间的体光栅(volumetric gratings)，耦合出的光束自第一表面从波导器件中耦合出来。
在一些实施例中，所述波导器件进一步包括与第四表面相对的长形第三表面。光源通过第三表面将光耦合进入波导器件，以形成耦合入的光束。来自光源的光准直成与所述长形第三表面对应的线形。
在一些实施例中，在第一表面或第二表面中的至少一个表面上设置棱镜，光源通过棱镜将光耦合进入波导器件，以形成耦合入的光束。
在一些实施例中，所述波导器件进一步包括第二光栅结构，所述第二光栅结构设在第一表面或第二表面中的至少一个表面上。光源通过所述第二光栅结构将光耦合进入波导器件，以形成耦合入的光束。
在一些实施例中，光吸收材料层为着色阳极氧化铝层。
根据本发明的另一个方面，一种光投射系统包括波导器件，所述波导器件包括第一表面、第二表面、第四表面和光吸收材料层，所述第一表面包括第一光栅结构；和光源，所述光源将光耦合进入波导器件以形成耦合入的光束。所述波导器件构造为：引导耦合入的光束在第一表面和第二表面之间进行全内反射。所述第一光栅结构构造为：干扰全内反射以使得至少部分耦合入光束从波导器件耦合出来并从第一表面投射出去，从波导器件耦合出的这部分耦合入光束形成耦合出光束，所述耦合出光束配置为：在耦合出光束投射的表面上形成点阵。耦合入的光束经全内反射后的其余部分在各第一光栅结构耦合出后到达第四表面。所述第四表面包括第一光吸收材料层，用于吸收耦合入光束的其余部分。所述光吸收材料层与第二表面平行且与第二表面有间隔。
在一些实施例中，所述光投射系统进一步包括检测器，所述检测器配置成用来接收远处物体在多个位置对耦合出光束的反射，以测定所述多个位置相对于光投射系统的距离。
根据本发明的另一个方面，一种波导器件包括第一表面、第二表面、第四表面和光吸收材料层。所述第一表面包括第一光栅结构。所述波导器件构造为：引导耦合入的光束在第一表面和第二表面之间进行全内反射。第一光栅结构构造为：干扰全内反射以使得至少部分耦合入光束从波导器件耦合出来并从第一表面投射出去，从波导器件耦合出的这部分耦合入光束形成耦合出光束，所述耦合出光束配置为：在耦合出光束投射的表面上形成点阵。
本文在此所公开的系统、方法和非暂时性计算机可读介质的这些和其他特征，以及操作方法、结构相关元件的功能、部件的组合和制造的经济性，将参考附图通过下文的描述和权利要求变得更加清楚，所有这些形成了本说明书的一部分，其中附图标记标明了各附图中的相应部件。然而需要明确理解的是，附图仅用于说明和描述，而不作为对本发明的限制。
附图说明
本发明的各种实施例的特征在所附的权利要求中进行了阐述。所述详细描述阐述了利用本发明的原理的说明性实施例，以及其附图。为了更好地理解本发明的特征和有益效果，可参考详细描述了利用本发明的原理的阐述性实施例的具体说明，该说明所附的附图包括：
图1为根据本发明各实施例的光投射系统的示意图。
图2为根据本发明各实施例的示例性光投射系统的侧视图。
图3为根据本发明各实施例的示例性光投射装置的侧视图。
图4A-图4I为根据本发明各实施例的从光源耦合入光投射结构的侧视图。
图5A-图5F根据本发明各实施例的从光投射结构耦合出的侧视图。
图6A为对根据本发明各实施例的示例性用于投射光的光投射装置的侧视图。
图6B为根据本发明各实施例的光栅耦合效率相对于光栅深度和占空比的示意图。
图6C为根据本发明各实施例的光栅耦合效率相对于光栅占空比的示意图。
图7A为根据本发明各实施例的用于投射光的光投射装置的立体图。
图7B为根据本发明各实施例的与耦合出光束对应的点阵的示意图。
图8A为根据本发明各实施例的用于投射光的光投射装置的立体图。
图8B为根据本发明各实施例的耦合出光束角度相对于光栅周期的示意图。
图9A为对根据本发明各实施例第一表面上示例性光栅的俯视图。
图9B为根据本发明各实施例耦合出光束角度相对于光栅旋转角度的示意图。
图10为对根据本发明各实施例第一表面上示例性光栅的俯视图。
图11为对根据本发明各实施例第一表面上示例性光栅的俯视图。
图12为对根据本发明各实施例的示例性用于投射光的光投射系统的示意图。
图13为对根据本发明各实施例的示例性用于投射光的光投射系统的示意图。
图14为对根据本发明各实施例的示例性用于投射光的光投射系统的示意图。
具体实施方式
光投射是三维特征检测、三维地图等应用的关键一步。例如，工业零件检查和医学检查使用的深度相机模组需要测定深度信息。参考图1，在这种应用中，一个或多个光源(例如，光投射系统102的部件)可将预定图形的结构光光束投射到物体(例如，物体104，如人脸)上，然后检测器(例如，检测器103)捕获光束的反射光来测量各种光学参数。所述光投射系统102和所述检测器103可设在同一装置(例如，装置101)或不同装置上。虽然显示为不同的部件，但检测器103可为光投射系统102的一部分，并配置成用来接收远处物体104在多个位置对投射光束的反射，以测定所述多个位置相对于光投射系统102的距离。光投射系统102可在各种系统或装置上实施，例如，手机、电脑、平板电脑、穿戴式设备，车辆等等。可将物体处极其平整的反射平面作为基准，基准对投射光的反射可预设为基准反射光束。可基于检测到的反射光束和基准反射光束之间的差值测定面部特征，这种差值显示为基准反射光束的偏移或畸变(shifts or distortions)。这种测定方法称为三角测量法。
目前用于投射结构光束的光投射技术采用随机点阵的投射法。对多个激光器进行随机排列获得随机点阵会不可避免地提高成本和模组尺寸并增大集成难度。
为了至少减少现有技术的缺点，本发明提供了光投射系统和方法。在各实施例中，光源可通过波导器件的一个表面将光束耦合进入波导器件中，然后波导器件通过另一个表面上的光栅投射出多个光束，以形成分散的 输出光束。所述光源可以为单个激光器(例如，边发射激光器(edge-emitting laser)、垂直腔面发射激光器(VCSEL))、发光二极管或类似物，因此不必像现有技术中一样需要使用多个激光器。由于可用标准光刻技术制作波导器件，因此可进一步降低制造成本。另外，由于可将波导器件集成在衬底上，因此可减小光投射系统的整体尺寸。进一步地，本发明的波导器件受益于不存在零级衍射的干涉(zeroth order diffraction interference)，因为全内反射约束使得零级透射不可能发生。
如本领域普通技术人员所理解的，波导器件是通过将波扩散(expansion)限制在一个或多个维度而以最小能量损失引导波(例如，如本发明中的电磁(光)波)的结构。
为此，在一些实施例中，一种光投射系统包括波导器件、光源和检测器，所述波导器件包括第一表面和第二表面，所述第一表面包括第一光栅结构；所述光源将光耦合进入波导器件以形成耦合入的光束。所述波导器件构造为引导耦合入的光束在第一表面和第二表面之间进行全内反射。光栅结构(例如，各第一光栅结构)构造为干扰全内反射以使得至少部分耦合入光束从波导器件耦合出来，从波导器件耦合出的这部分耦合入光束形成耦合出光束。所述检测器配置成用来接收远处物体在多个位置对耦合出光束的反射，以测定所述多个位置相对于光投射系统的距离。由此测定物体表面的拓扑结构。下面参考图2和图3，对包括光源和光投射结构(例如，波导器件)的光投射装置进行更加详细的描述。所述光投射系统可进一步包括投射透镜结构，同样见图2。耦合出的光穿过投射透镜结构到达远处的物体。
图2为对根据本发明各实施例的示例性光投射系统102的侧视图。光投射系统102可以在各种系统或装置上实施，例如，手机、电脑、平板电脑、穿戴式设备，车辆等等。
如图2所示，示例性光投射系统102可包括光投射装置211和可选的投射透镜结构231(或称为投射透镜)。在一些实施例中，光投射装置211包括光源201和光投射结构202。所述光源201包括单个激光器(例如， 边发射激光器、垂直腔面发射激光器(VCSEL))、带光准直的发光二极管(LED)或类似物。或者，所述光源201可包括多个激光器或二极管(例如，边发射激光器阵列、VCSEL阵列、LED阵列)。所述光投射结构202可包括下文将详述的波导器件。自光投射结构202耦合出的光可为垂直于表面，聚焦或散焦。
在一些实施例中，自光投射装置211射出的光束(耦合出的光束)可从光投射装置211的一个表面耦合出。这样，可让光束穿过投射透镜结构231投射向空间中。即，可将所述投射透镜结构231(例如，一个或多个透镜)设在波导器件的上方(例如，在后面所述波导器件的第一表面的上方)。投射透镜结构231可配置成接收耦合出的光束，并将所述耦合出的光束投射到环境中的远处物体上。或者，将光束从光投射装置211直接投射到空间中。所述投射透镜结构231可包括各种透镜或透镜组合(例如，一个到六个单独的透镜)，用于控制投射光束的方向。
在一些实施例中，所述投射透镜结构231可配置成能增大或减小投射光束阵列的视野。例如，所述投射透镜结构231可通过分散所述投射光束阵列增大视野，或通过会聚投射光束阵列减小视野。
在一些实施例中，所述投射透镜结构231可配置成准直各耦合出的光束。例如，按照不同应用的工作距离要求，经投射透镜结构231准直后的投射光束阵列的激光束腰从10mm至1m不等。这样，投射透镜结构231可准直输出光以在观测的距离处(例如，根据应用，在10cm至10m的范围内)形成清晰的图像(例如，点阵)。
图3为对根据本发明各实施例的示例性光投射装置211的侧视。图3所示和下文所述的结构和操作为示例性的。
在一些实施例中，光源201发射光，以光学方式将光在一个表面的耦合入(将光耦合进入光投射结构202中)区域上耦合进光投射结构202。耦合入设置包括端面耦合、光栅耦合、棱镜耦合或类似方式。进入光投射结构202后，光在光投射结构202内的第一表面和第二表面之间进行全内反射。所述光投射结构202可由高折射率的材料(例如，树脂玻璃、石英 玻璃、单晶硅和熔融石英)制成。在一个例子中，若使用折射率为1.45的石英玻璃，全内折射的临界角度为44°。当光以相对于第一或第二表面大于临界角的角度在光投射结构202中传播，照射在光投射结构202的第一或第二表面上时，保持了全内反射。在光投射结构202中传播的光可在各个耦合出区域(例如，在第一表面上)从光投射结构202耦合出来。例如，所述耦合出区域可为具有耦合出结构(例如，透射光栅、反射光栅、反射器)的区域。
在一些实施例中，所述光投射结构202包括第一表面和第二表面。所述第一表面或第二表面中至少一个表面包括第一光栅结构。在本发明中，光栅结构可指一个栅格(例如，光学栅格)，其是平行的、相同的长形元件匀称地间隔排布的组合。在本图中，例如，示出了脊形光栅(ridge grating)的轮廓，且各脊形光栅可包括多个相同的、平行的长形的脊(见图7A的光栅A)。所述光投射结构引导耦合入的光束在第一表面和第二表面之间进行全内反射。各第一光栅结构干扰全内反射以使得至少部分耦合入光束从光投射结构耦合出来，从光投射结构耦合出的这部分耦合入光束为耦合出光束。这样，在波导器件内传播的一个耦合入光束可通过光栅从波导器件中耦合出来，以得到多个耦合出光束。下面详述各种耦合入和耦合出机构。
图4A-图4I为根据本发明各实施例的从光源耦合入到光投射结构(例如，平面波导(planar waveguide))的侧视图。图4A-图4I所示和下文所述结构和操作为示例性的。假定图4A、图4F、图4G、图4H和图4I中的平面波导处于水平位置，光源201可基本上在水平面内发射光，而耦合出的光基本上在垂直平面内传播。在图4B,图4C，图4D，图4E中，光源201可基本上在垂直平面内发射光，而耦合出的光基本上在所述垂直平面内传播。所述水平平面和所述垂直平面是相对的，对环境并不构成限制。
在一些实施例中，如图4A所示，光源201发出的光可通过光投射结构202的一个表面利用“端面耦合”耦合进入光投射结构202中。耦合入光的环境折射率、光投射结构202的折射率、波长和耦合入光在光投射结构 202的第三表面上的入射角满足本领域技术人员所理解的“端面耦合”条件。在光投射结构202内，光在所述光投射结构202的第一表面和第二表面之间进行全内反射，并从所述光投射结构202的第一表面耦合出来。或者，若光源201比第三表面大，可使用透镜通过“端面耦合”将来自光源201的光聚焦在光投射结构202中。
在一些实施例中，如图4B和图4C所示，光源201发出的光可通过耦合入光栅利用“光栅耦合”耦合进入光投射结构202中。即，所述光投射结构进一步包括第二光栅结构，所述第二光栅结构设在第一表面或第二表面中的至少一个表面上。光源通过所述第二光栅结构将光耦合进入光投射结构，形成耦合入的光束。如图4B所示，所述耦合入光栅可制作在所述光投射结构202的第一表面上。虽然图中显示所述耦合入光栅与第一表面齐平，但也可使其高于或低于第一表面，只要能保持随后的全内反射。耦合入光的环境折射率、光投射结构202的折射率、耦合入光栅的几何构造、波长和耦合入光在光投射结构202的第三表面上的入射角满足本领域技术人员所理解的“光栅耦合”条件。在光投射结构202内，光在所述光投射结构202的第一表面和第二表面之间进行全内反射，并从所述光投射结构202的第一表面耦合出来。图4C与图4B类似，除了所述耦合入光栅可制作在所述光投射结构202的第二表面上。
在一些实施例中，如图4D到4I所示，光源201发出的光可通过棱镜利用“棱镜耦合”耦合进入光投射结构202中。即，所述光投射结构可进一步包括棱镜，所述棱镜设在第一表面、第二表面或第三表面中的至少一个表面上。光源通过棱镜将光耦合进入光投射结构，形成耦合入的光束。在本发明中，“设在......(一个物体)上”还包含“靠近......(所述物体)设置”。棱镜和光投射结构202之间的任何间隙可用光学胶或另一种折射率的匹配材料填充。
如图4D所示，所述棱镜可设在所述光投射结构202的第三表面上。光源201可设在第二表面边上，将光发射到棱镜中。光在棱镜内发生一次反射，并在第三表面从棱镜耦合进入光投射结构202。棱镜的折射率、光投 射结构202的折射率、棱镜的几何构造和来自光源201的光的入射角满足本领域技术人员所理解的“光栅耦合”条件。在光投射结构202内，光在所述光投射结构202的第一表面和第二表面之间进行全内反射，并从所述光投射结构202的第一表面耦合出来。图4E与图4D类似，除了可将棱镜倒过来以使光源201设在第一表面边上。
如图4F所示，所述棱镜可设在所述光投射结构202的第一表面上。光源201发出的光可进入棱镜。在棱镜和光投射结构202之间的第一表面处，光的隐失模(evanescent mode)可耦合进入光投射结构202中。棱镜的折射率、光投射结构202的折射率、棱镜的几何构造和来自光源201的光的入射角满足本领域技术人员所理解的“相位匹配(phase matching)”条件。在光投射结构202内，光在所述光投射结构202的第一表面和第二表面之间进行全内反射，并从所述光投射结构202的第一表面耦合出来。图4G与图4D类似，除了所述棱镜可设在所述光投射结构202的第二表面上。
在一些实施例中，图4H与图4D类似，除了棱镜设在第一表面上外，光在棱镜内的坡面上发生一次反射，然后耦合进入光投射结构202中。图4I与图4H类似，除了棱镜设在第二表面上。图4F和图4G中使用的棱镜可为规则棱镜，图4H和图4I中使用的棱镜可为楔形棱镜。
图5A-图5F为根据本发明各实施例的从光投射结构(例如，平面波导)耦合出的侧视图。图5A-图5F所示和下文所述结构和操作为示例性的。为了简明起见，图5A-图5F省略了耦合入和光在光投射结构202中的传播。
在一些实施例中，光投射结构包括平面波导。第一表面和第二表面相互平行且为平面波导的最大表面。耦合出光束自第一表面从光投射结构中耦合出来。所述第一表面或第二表面中包括第一光栅结构。当第二表面包括第一光栅结构时，所述光投射结构可进一步包括设在第二表面上的金属层。或者，所述第一光栅结构包括设在第一表面和第二表面之间的体光栅。即，耦合入光束在光投射结构202中进行全内反射。虽然其余部分继续进行全内反射，但有一部分光在照射到第一表面、第二表面上或波导器件 内的耦合出结构上时可能会不发生全内反射，而是自其一个表面(例如，第一表面)从波导器件射出。下文描述各种耦合出结构(透射光栅、反射光栅、反射器等)。
在图5A-图5C中，所示波导器件结构包括光栅，可允许一个或多个衍射级从波导器件中耦合出来。在一些实施例中，如图5A所示，光栅可制作在光投射结构202第一表面上的各个耦合出区域。所述耦合出区域对应于各个全内反射区域，光在波导器件内传播时，有一部分光可自各耦合出区域从波导器件中耦合出来(例如，进入空气中)。
在一些实施例中，如图5B(构型1)所示，衍射光栅可制作在光投射结构202第二表面上的各个耦合出区域。即，该波导器件包括：(1)底层，光栅制作在其上面，所述底层具有第一折射率；和(2)顶层，其形状与底层互补。所述耦合出区域可对应于各个全内反射区域，照射在各耦合出区域上的一部分光可转向第一表面，随后自第一表面从波导耦合出来。
类似地，图5B还示出了光栅制作在第二表面上的构型2。所述光栅的折射率可与波导器件的折射率相同，也可不同。
在一些实施例中，如图5C所示，微透镜阵列可设置在与图5B中耦合出区域的位置对应地在第一表面上，使得能对耦合出光进行准直、使其平行或其它控制。
在一些实施例中，如图5D所示，折射光栅可制作在光投射结构202第一表面上的各个耦合出区域。例如，可从第一表面上蚀刻掉图中所示三角形轮廓的光栅。所述光栅对应于耦合出区域，一部分全内反射光可自所述光栅从波导器件中耦合出来。
在一些实施例中，如图5E所示，反射光栅可制作在光投射结构202的第二表面上的各个耦合出区域。例如，可从第二表面上蚀刻掉图中所示三角形轮廓的光栅。所述光栅对应于耦合出区域，一部分全内反射光可自所述光栅向第一表面反射，随后从波导器件中耦合出来。
在一些实施例中，如图5F所示，可在波导器件内制作体光栅。例如，体光栅的周期性是重复周期段(repeating periodic sections)之间的交替折 射率(alternating refractive index)。所述折射率变化分界面对应于耦合出区域，一部分全内反射光可自所述分界面向第一表面反射，随后从波导器件中耦合出来。
第一光栅结构的各种构型可对耦合出的光束进行控制。如下文所述，耦合出效率可由光栅深度(也称“厚度”)和光栅占空比(图6A-图6C)决定，耦合出光束相对于表面法线的角度可由光栅周期(图8A-图8B)决定，耦合出光束的旋转角度可由光栅方向(grating orientation)决定(图9A-图9B)。
在一些实施例中，所述光栅(第一光栅结构)干扰全内反射以使耦合出光束从第一表面投射出去，且所述耦合出光束设置为使得在耦合出光束投射的表面上形成点阵。例如，所述耦合出光束可在与第一表面平行的平面上形成点阵。在一个例子中，耦合出的光束垂直于第一表面传播，耦合出光束与第一表面平行的截面包括与耦合出光束对应的随机点阵。在另一个例子中，耦合出的光束从第一表面发散形成倒立光锥，倒立光锥与第一表面平行的截面包括与耦合出光束对应的随机点阵(图7B)。在另一个例子中，耦合出光束从第一表面会聚形成直立光锥，然后发散以在直立光锥的上方形成倒立光锥；直立或倒立光锥与第一表面平行的截面包括与耦合出光束对应的点阵。如下文所述，光点图形不限于所示例子，可包括各种其它构型。下面参考图6A至图9B进行的描述可借用图10或图11中所示的坐标系。即，所述波导器件的所述第一表面(或第二表面)在x轴方向与y轴方向彼此垂直的x-y平面内，耦合入的光束基本上沿着x-y平面的x轴方向在光投射结构内传播，耦合出的光束基本上沿着与x-y平面正交的z轴方向传播。所述光栅结构以相应的(x，y)位置可随机地分布在x-y平面内。在一些实施例中，光栅的尺寸约为2μm至30μm，波导器件上的光栅数量约为几百到一百万个，平均栅距(两个最接近光栅之间的间隔)约为5μm至100μm。
图6A为对根据本发明各实施例的示例性光投射系统211的侧视图。图6A所示和下文所述结构和操作为示例性的。图6A可对应于上述图5A，下面对光栅耦合出机构进行描述。
在一些实施例中，耦合出光束的方向可遵循以下公式：
Figure PCTCN2019094785-appb-000001
其中，m为衍射级次；λ为波长；Γ为光栅周期；n为波导器件的折射率；θ m为耦合出光束与第一表面法线的夹角；及θ i为在波导器件内进行全内反射的光束与第一表面法线的夹角。
在一些实施例中，+1级衍射(m＝1)的有效率折射率与波导支持模式的有效折射率匹配时，发生所述的耦合出(在波导器件内进行全内反射的光束自设有光栅结构的区域从波导器件中耦合出来)。因此，为得到与法线平行传播的耦合出光束，(即，θ m＝0)，可由下式得到光栅周期(图中用“周期”标示)：
Figure PCTCN2019094785-appb-000002
例如，当波导器件为石英玻璃(n＝1.45)时，λ＝940nm，且θ i＝60°，可得到Γ为748nm。因此，光栅周期影响耦合出光束与法线的夹角。
将式(2)代入式(1)，可得到：
sinθ m＝(m-1)×n×sinθ i    (3)
进一步地，根据临界角为θ c的全内反射条件：
Figure PCTCN2019094785-appb-000003
可得到
Figure PCTCN2019094785-appb-000004
因此：
n×sinθ i＞1    (5)
为了同时满足(3)和(5)，其中m为整数且|sinθ m|≤1，因此m只能为1。在无其它透射衍射级的光干扰时，所述耦合出(在波导器件内进行全内反射的光束自设有光栅结构的区域从波导器件中耦合出来)可以仅产生m＝+1级的耦合出光。这是现有光投射技术不具有的一种优点。
图6B为根据本发明各实施例的耦合效率随光栅深度和占空比变化的仿真结果示意图。
在一些实施例中，光栅具有能产生高耦合效率的尺寸，耦合效率为进行全内反射的光在光栅处从波导器件中耦合出来的百分比(部分)。因此，在上下文中，耦合效率可理解为耦合出效率。光栅周期固定时，耦合效率由光栅深度和占空比(各周期中脊形结构所占的百分比)决定。参考图6A和图9A中的标示“脊宽”和“周期”，用脊宽除以周期得到占空比。占空比又称填充系数。对于图6B，当λ＝940nm且θ i＝60°时，可得到Γ为748nm。
图6B显示了两种不同波导模式的仿真耦合效率(即，TE模式和TM模式光在波导器件中的传播)。x轴代表占空比，y轴代表光栅深度。较亮区域代表较高的耦合效率。对于TE模式，最高耦合效率为9.8％，在占空比为0.43、厚度为0.35μm时出现。对于TM模式，最高耦合效率为2.8％，在占空比为0.52、厚度为0.3μm时出现。因此，可通过设计光栅深度和占空比获得各种耦合效率。进一步地，通过调整光栅深度，可获得比所述9.8％效率更大的耦合效率。
在一个例子中，从图6B的TE模式图提取，当λ＝940nm，θ i＝60°,Γ＝748nm且厚度＝0.35μm时，可得到相对于占空比的耦合效率，如图6C所示。在占空比为0.43、厚度为0.35μm时，具有相同的峰值耦合效率9.8％。
在一些实施例中，由于光在进行全内反射时有一部分在各光栅处从波导器件中耦合出来，每次耦合出后，波导器件中其余光的功率会减小。为确保点阵中耦合出光束具有大致相同或近似的功率，可将光栅设计成使耦合效率随着光栅距光源201的距离增大而增大。例如，再回到图6A，通过调整占空比和光栅深度，可使光栅Y的耦合效率大于光栅X的耦合效率，以确保自光栅Y和光栅X的耦合出光具有相同或近似的功率。
因此，在一些实施例中，各所述光栅结构与耦合出效率相关联。耦合出效率沿着x轴方向呈单调递增。耦合出效率取决于光栅结构的光栅深度和占空比。光栅周期的光栅深度或占空比中至少有一个在x轴方向上变化，使耦合出效率沿着x轴方向单调递增。在一个例子中，光栅结构的光栅 深度在x轴方向上单调递增，使耦合出效率沿着x轴方向单调递增。在另一个例子中，光栅结构的占空比在x轴方向上单调递增，使耦合出效率沿着x轴方向单调递增。在另一个例子中，x-y平面包括与沿x轴方向的各个位置范围对应的多个区域，所述区域包括第一区域和第二区域。第一区域最靠近耦合入光束耦合入光投射结构的区域。第二区域距离耦合入光束耦合入光投射结构的区域最远。相同区域中的光栅结构具有相同或近似的耦合出效率。耦合出效率沿着x轴方向单调递增使得第一区域内自各光栅结构的耦合出光束的功率与第二区域内自各光栅结构的耦合出光束的功率相同或近似。
图7A为根据本发明各实施例的光投射装置211的立体图。图7A所示和下文所述结构和操作为示例性的。
如图7A所示，在一些实施例中，光投射结构202包括平面波导，该平面波导具有制作在第一表面上的光栅。图7A所示光投射结构202类似于图6A所示的光投射结构202，除了图7A中的耦合出光束垂直于第一表面。光源201包括带光准直的一个或多个激光器或LED。所述激光器或LED可成排地设在平面波导的侧表面中。
在一些实施例中，光栅(例如，光栅A、光栅B、光栅C、光栅D等)可制作在第一表面上的随机位置。所述光栅可具有相同的光栅周期。各耦合出光束自各个光栅从波导器件中耦合出来。因此，从顶部观察时，耦合出光束可形成随机点阵，如图7B所示。所示点阵图形仅为示例性的。基于对光栅结构的构型(例如，通过调整周期、方向、深度、占空比、波导器件上的(x，y，z)位置、数量等)，可获得任何点阵图形以满足应用需求。
图8A为根据本发明各实施例的光投射装置211的立体图。图8A所示和下文所述结构和操作为示例性的。
光投射装置211类似于图7A与图8A，还提供随机点阵，除了图8A中的光栅可具有不同的光栅周期。如图8A所示，在一些实施例中，光栅(例如，光栅E、光栅F、光栅G、光栅H等)可具有不同的光栅周期Γ。 根据上述式(1)，θ m随光栅周期而变化Γ。即，耦合出光束可以与正交方向不同夹角传播。因此，θ m的变化也会增大点阵的随机性。图8B显示了耦合出光束角度(在相对于z轴方向的x-z平面内)对光栅周期的图线。如图所示，在垂直于第一表面且沿着光在波导器件内传播的方向(x轴方向)的同一垂直平面内，通过改变光栅周期可将耦合出光束与正交方向的夹角控制在-5°至15°之间。虽然耦合出光束还可具有y轴方向的分量，但图8A与图8B关注x轴方向上的分量。
因此，在一些实施例中，各光栅结构与周期相关联。对于沿着x轴方向的光栅结构，周期会有所变化。周期的变化导致耦合出光束以一在x轴方向上的角度偏差范围从波导器件中耦合出来。在一个例子中，周期沿着x轴方向单调递增。周期沿着x轴方向的单调变化导致耦合出光束以一在x轴方向上的角度偏差范围从光投射结构中耦合出来。
图9A为对根据本发明各实施例的第一表面上示例性光栅的俯视图。如图9A所示，在一些实施例中，光栅在x-y平面内可具有各种方向。可参考光栅凸脊的方向来体现光栅的方向。例如，光栅M可排列成使其凸脊垂直于x轴方向，光栅N可排列成使其凸脊与x轴方向成正旋转角度，且光栅K可排列成使其凸脊与x轴方向成负旋转角度。
在一些实施例中，耦合入光在x轴方向上在波导器件内从左向右传播。自光栅M耦合出的光在y轴方向上的分量为0。即，忽略x轴方向上的分量，自光栅M耦合出的光在z轴方向上传播。自正旋转角度的光栅N耦合出的光具有y轴负方向分量。即，忽略x轴方向上的分量，自光栅N耦合出的光在z轴方向-y轴负方向上传播。自负旋转角度的光栅K耦合出的光具有y轴正方向分量。即，忽略x轴方向上的分量，自光栅K耦合出的光在z轴方向-y轴正方向上传播。因此，综合考虑自光栅M、N和K耦合出的光束，耦合出光束在y-z平面内会聚。图9A为对下面图10中所述的光栅方向控制以得到会聚的耦合出光束的简化示意图。下图11显示了图9B的反向以得到发散的耦合出光束。
图9B显示了耦合出光束角度(在相对于z轴方向的y-z平面内)相对于光栅旋转角度(相对于x轴方向)的曲线图。在此曲线图中，通过使光栅相对于x轴方向的方向在45°和-45°之间变化，可将耦合出光束角度相对于参考方向控制在约-70°和70°之间。图9B仅为示例性的，可使用替代方向参考系。虽然耦合出光束还可具有x轴方向的分量，但图9A与图9B关注y轴方向上的分量。
因此，在一些实施例中，各光栅结构与相对于z轴方向的旋转角度相关联，且对于沿y轴方向的光栅结构，旋转角度会有所变化。旋转角度的变化导致耦合出光束以在一y轴方向上的角度偏差范围从波导器件中耦合出来。在一个例子中，旋转角度顺时针或逆时针单调变化。旋转角度的单调变化使耦合出光束以不同的y轴方向分量传播。
图10和图11都是根据本发明各实施例的第一表面上示例性光栅(第一光栅结构)的俯视图。或者，光栅可制作在第二表面上或按图5A-图5F中所示的另一构型进行制作。图10和图11所示和下文所述结构和操作为示例性的。图10和图11中的光栅可结合图6A-图9B所述的以下几种情况：通过光栅深度和占空比控制耦合出效率，通过光栅周期控制耦合出光束相对于法线的角度和通过光栅方向控制耦合出光束的旋转角度。如图10和图11所示，平面波导在x-y平面内，且z轴方向为表面正交方向(与x-y平面垂直)。在本发明中，x轴方向和y轴方向的定义如本图中所示。z轴方向垂直于x-y平面，并指向纸张平面的外面。x轴、y轴和z轴方向又称x轴、y轴和z轴正方向，其相对方向称为x轴、y轴和z轴负方向。耦合入光可从左侧进入波导器件，其中部分光通过光栅从波导器件耦合出来，一些残余光(又称其余光)留下并在x轴方向上继续传播。耦合入光可产生自一个或多个激光器。第一光栅结构与光栅深度、占空比、周期和在x-y平面内相对于z轴方向的方向都相关联。在x轴方向上不同位置处的第一光栅结构具有至少一种不同的光栅深度或不同的光栅占空比。x轴方向上不同位置处的第一光栅结构具有不同的周期。y轴方向上不同位置处的第一光栅结构具有不同的方向。
在一些实施例中，所述波导器件进一步包括与第四表面相对的长形第三表面。第三表面相对于第一和第二表面的位置如上所述。光源通过第三表面将光耦合进入波导器件中(在图10和图11所述的光入射方向上)，以形成耦合入光束。来自光源的光准直成与所述长形第三表面对应的线形。在使用单个激光器的一个例子中，激光器输出光束可通过准直透镜或准直透镜阵列准直成线形，所述线形光在平面波导的第三表面上，随后可通过第三表面耦合进入平面波导内。
在一些实施例中，可通过光栅方向和光栅周期控制耦合出光束的发散。例如，可通过光栅方向控制耦合出光束在y轴方向上的发散，还可通过光栅周期控制耦合出光束在x轴方向上的发散。在图10和图11的y轴方向上，y-z平面(包含y轴和z轴的平面)内的耦合出光束相对于z轴方向的角度随光栅的旋转方向而变化。详细解释参考上面结合图9A和图9B的论述。在图10和图11的x轴方向上，x-z平面(包含x轴和z轴的平面)内的耦合出光束相对于z轴方向的角度随光栅周期而变化。耦合出光束的输出角度随着光栅周期而增大。详细解释参考上面结合图8A和图8B的论述。因此，可通过控制光栅方向和光栅周期来得到会聚的耦合出光束(例如，成锥形，从第一表面会聚而成)或发散的耦合出光束(例如，成倒锥形，从第一表面发散而成)。
图10显示了为得到会聚的耦合出光束而进行的示例性光栅方向和周期控制，图11显示了为得到发散的耦合出光束而进行的示例性光栅方向和周期控制。
在一些实施例中，图10和图11示出了带光栅方向控制的示例性光栅结构。在图10中，光栅方向可在y轴方向上由下向上变化，以使光栅相对于第一表面的法线顺时针旋转。即，在图10中，假定y轴方向为参考方向，第一表面中间水平段的光栅无旋转，第一表面底部水平段的光栅负向旋转(向左倾斜)，且第一表面顶部水平段的光栅正向旋转(向右倾斜)，使得最上面光栅的耦合出光束具有最大y轴负方向分量，最下面光栅的耦合出光束具有最大y轴正方向分量，与图9B及其描述一致。即，沿y轴方 向的光栅结构的方向可顺时针旋转，以使耦合出光束从第一表面会聚在y-z平面内。在图11中，光栅方向可在y轴方向上由下向上变化，以使光栅相对于第一表面的法线逆时针旋转。即，在图11中，假定y轴方向为参考方向，第一表面中间水平段的光栅无旋转，第一表面底部水平段的光栅正向旋转(向右倾斜)，且第一表面顶部水平段的光栅负向旋转(向左倾斜)，使得最上面光栅的耦合出光束具有最大y轴正方向分量，最下面光栅的耦合出光束具有最大y轴负方向分量，与图9B及其描述一致。即，沿y轴方向的光栅结构的方向逆时针旋转，以使耦合出光束从第一表面发散在y-z平面内。这样，改变光栅方向(例如，在y轴方向上单调地顺时针或逆时针)将耦合出光从仅在表面法线方向(垂直于第一表面)上扩展到在y轴方向上具有一定的视野(field-of-view)。y轴方向上的视野在图10中会聚，而在图11中发散，分别使耦合出光束发生会聚和发散。
在一些实施例中，图10和图11还示出了带光栅周期控制的示例性光栅结构。在图10中，光栅周期在x轴方向上减小，使得x轴方向上的第一个耦合出光束具有最大x轴正方向分量，x轴方向上的最后一个耦合出光束具有最大x轴负方向分量，与图8B及其描述一致。这样，耦合出光束在x轴方向上会聚。在图11中，光栅周期在x轴方向上增大，使得x轴方向上的第一个耦合出光束(从第一个光栅耦合出)具有最大x轴负方向分量，x轴方向上的最后一个耦合出光束(从最后一个光栅耦合出)具有最大x轴正方向分量，与图8B及其描述一致。这样，改变光栅周期(例如，在x轴方向上单调递增或递减)将耦合出光从仅在表面法线方向(垂直于第一表面)上扩展到在x轴方向上具有一定的视野。周期可在x轴方向上单调递减，以使耦合出光束从第一表面会聚在x-z平面内。周期可在x轴方向上单调递增，以使耦合出光束从第一表面发射在x-z平面内。在图10中，x轴方向上的视野会聚，而在图11中发散，分别使耦合出光束发生会聚和发散。
参考图10，光栅周期在x轴方向上减小(例如，单调递减)结合光栅方向在y轴方向上顺时针旋转(例如，y轴方向上的光栅，相对于z轴方向 单调地顺时针旋转)可使耦合出光束从第一表面会聚。即，周期在x轴方向上单调递减，同时沿y轴方向的光栅结构的方向顺时针旋转，可使耦合出光束从第一表面会聚。在一个例子中，会聚的光束可形成直立光锥，所述光锥从第一表面投射出去并朝第一表面上方的一个点会聚，但是一旦穿过会聚点，光束发散并在直立光锥的顶部形成倒立光锥。
参考图11，光栅周期在x轴方向上增加(例如，单调递增)结合光栅方向在y轴方向上逆时针旋转(例如，y轴方向上的光栅，相对于z轴方向单调地逆时针旋转)可使耦合出光束从第一表面发散。即，周期在x轴方向上单调递增，同时沿y轴方向的光栅结构的方向逆时针旋转，可使耦合出光束从第一表面发散。在一个例子中，发散光束可形成倒立光锥，所述倒立光锥从第一表面投射出去并从第一表面发散。
在一些实施例中，波导器件中的光功率沿着传播方向(图10和图11中的x轴方向)减小，因此射在光栅上供耦合出的全内反射光束的功率沿着传播方向减小。为了获得统一的耦合出光束的输出功率，耦合出效率可沿着传播方向增大以补偿功率的损失。耦合出效率可在传播方向上单调递增。可通过改变光栅深度和/或光栅占空比来改变耦合出效率(见如上面图6B和图6C的论述)。用光栅深度和光栅占空比的适当组合可获得任意耦合出效率。光栅厚度沿着传播方向可单调递增或不单调递增。光栅占空比沿着传播方向可单调递增或不单调递增。各光栅厚度和光栅占空比在传播方向上不必遵循任何单调趋势，只要光栅厚度和光栅占空比的组合能为耦合出光束沿着传播方向增大耦合出效率。
参考图10和图11，在一些实施例中，可将第一表面设计成条状全内反射区(全内反射TIR 1区、TIR 2区等)，这些条状全内反射区具有对应的耦合出效率η 1,η 2,…,η n，从η 1到η n逐渐增加以使输出功率保持恒定。在一个例子中，这种关系可为P n-1×η n-1＝P n×η n，其中P n＝P n-1×(1-η n-1)。若要改变耦合效率，可改变占空比和/或光栅深度。
图中第一表面上光栅位置的分布图10和图11可以是随机的。即，尽管遵从所述的光栅周期、光栅深度、光栅占空比和光栅方向趋势，但若第 一表面(或第二表面)在x-y平面内，光栅可相对于对应的(x，y)位置随机分布在x-y平面内。这里，随机分布指可不将光栅固定在第一或第二表面上的周期性位置(例如，二维格子位置、等间距的位置等)处。本文所述随机点阵对应于光栅位置的这种随机分布。光栅位置的随机分布可使算法误差最小化。算法误差对基于耦合出光束的检测不利。算法误差通常由周期性或其它非随机图形趋势引起，因为检测器为检测不同结构光束的反射之间的差异所运行的算法有时由于看起来相同，很难将图形的一部分与另一部分区分开来。
虽然图10和图11中光栅显示为三个凸脊，但各光栅可包括任一数量的凸脊或另一种替代光栅结构(例如，肋(rib)、埋藏脊(buried ridge)和扩散脊(diffused ridge))。凸脊轮廓可为方形、圆形、三角形等。虽然图10和图11所示为方形，但各光栅的外形可为圆形、椭圆形、矩形等。光栅的尺寸可为1个周期(约1μm)到整像素尺寸(约30μm)。在一些实施例中，若光栅足够大以致可忽略衍射极限，光点大小将随着光栅尺寸而增大，可通过控制光栅的尺寸得到理想的光点尺寸(投射光束的光束尺寸)。例如，若某一应用需要更多光点，则可将光栅的尺寸减少以将更多光点聚集在固定区域(例如，第一表面)。若某一应用需要更明亮的光点(更高的信噪比)，可增大光栅的尺寸，因为较大的光点具有更大的功率，因此更明亮。
图12为对根据本发明各实施例的示例性光投射系统102的示意图。所述光投射系统102可实施上面参考图4H描述的耦合入机构和上面参考图5B(构型2)描述的耦合出机构。
在一些实施例中，所述波导器件进一步包括反射层，所述反射层设在第二表面上且覆盖光栅结构。反射层包括一个或多个金属(合金)和/或非金属(例如，绝缘层(dielectric))子层。在一个例子中，反射层包括一个或多个子层，各个子层包括下列至少一种：铝、银、金、铜、钛、铬、镍、锗、铟、锡、铂、钯、锌、氧化铝、氧化银、氧化金、氧化铜、氧化钛、氧化铬、氧化镍、氧化锗、氧化铟、氧化锡、氧化铂、氧化钯、氧 化锌、氮化铝、氮化银、氮化金、氮化铜、氮化钛、氮化铬、氮化镍、氮化锗、氮化铟、氮化锡、氮化铂、氮化钯、氮化锌、氟化铝、氟化银、氟化金、氟化铜、氟化钛、氟化铬、氟化镍、氟化锗、氟化铟、氟化锡、氟化铂、氟化钯或氟化锌。当光栅制作在第二表面(如图所示)或在第一表面上时，一些光功率会因对称的一级衍射的而从波导器件中泄漏出来(例如，向下)。为了最小化或抑制这种泄露并使耦合效率最大化，可在第二表面上镀覆一个反射层(例如，金属层或高反射镀层)。金属可为铝、银、金、铜或另一种高反射金属。
图13为对根据本发明各实施例的示例性光投射系统102的示意图。所述光投射系统102可实施上面参考图4H描述的耦合入机构和上面参考图3描述的耦合出机构。
在一些实施例中，可使用所示光吸收材料层将较高光栅模式的泄露光或不完全耦合的残余光产生的背景噪音减至最小。要将波导器件射出的残余光减至最少，可直接在波导器件的侧壁上设置光吸收材料层(在波导器件中光传播的末端处)。要减少其它光栅模式的泄露光，光吸收材料层可设为与第二表面具有间隙，以防止破坏全内反射条件。光吸收材料层可为(着色)阳极氧化铝层、粗糙表面、炭黑涂层或另一种光吸收材料层。
即，光投射结构进一步包括第四表面、第一光吸收材料层和第二光吸收材料层。耦合入光束经全内反射后的其余部分在各光栅结构耦合出后到达第四表面。所述第四表面包括光吸收材料层，用于吸收耦合入光束的其余部分。所述第二光吸收材料层与第二表面平行且与第二表面有间隔。所述第二光吸收材料层可吸收从第二表面泄漏出波导器件的光。所述间隙可防止吸收仍在波导器件内传播的耦合入光。
图14为对根据本发明各实施例的示例性光投射系统102的示意图。所述光投射系统102可实施上面参考图4H描述的耦合入机构和上面参考图3描述的耦合出机构。
在一些实施例中，如图所示，可添加残余光耦合出设置，以通过上述端面耦合、光栅耦合或棱镜耦合将所述残余光从波导器件中耦合出来(在 波导器件中光传播的末端处)。可使用检测用光电二极管(例如，硅、锗或另一种二极管)等检测器来检测耦合出的残余光。在一个例子中，若发生任何事故(例如，芯片开裂、水进入(water damage)、蒸气进入(vapor damage)、激光器错位(laser dislocation)、耦合入棱镜错位或另一种失效事件)，失效点的全内反射条件将会破坏。利用阈值算法，通过检测光电二极管可及时检测到残余光变化的事件，并相应地关闭输入激光器，以确保眼睛安全。若不关闭输入激光器，一些激光光束会从光投射系统漏出。由于这些光束的功率未受到控制，因此会造成眼睛损伤。
上文所述的各种特征和过程可相互独立地使用，或以各种方式组合。所有可能的组合和子组合均在本发明的范围内。此外，在一些实施应用中可省略某些方法或过程块。此处描述的方法和过程不限于任何特定顺序，与之相关的块或状态可采用其他合适的顺序进行实施。例如，所述块或状态可采用不同于特定公开的顺序进行实施，或多个块或状态可组合到单个块或状态内。示例块或状态可采用串行、并行或其他一些方式进行实施。块或状态可添加至公开的示例性实施例，或从其中移除。在此描述的示例性系统和组件可采用不同于所描述的方式进行配置。例如，元件可添加至公开的示例性实施例，从其中移除，或相较于公开的示例性实施例进行重新布局。
在本说明书的通篇中，多个例子可作为单个例子进行所描述的组件、操作或结构的实施应用。虽然一个或多个方法的单个操作是作为独立的操作进行阐述和描述的，但是一个或多个单个操作可同时实施，且不是必须采用显示的顺序进行操作。在示例性配置中显示为独立组件的结构和功能可以作为组合结构或组件来实施应用。类似地，显示为单个组件的结构和功能可以作为单独组件来实施应用。这些和其他变型、修改、增加和改善均落入到本技术方案的范围内。
虽然本技术方案已经参照具体实施例进行了综述，但可以在不偏离本技术方案实施例广义范围的情况下，对这些实施例进行各种修改和变更。本技术方案的这些实施例可以单独地或共同地通过术语“发明”来表示，这 仅仅是为了方便。而并不是意味着，在实际公开了多个方案的情况下，将本申请的范围主动地限制于任何单个公开方案或概念。
本文对实施例进行了足够详细的描述说明，以使本领域内技术人员可以实施这些公开的方案。可以使用其他实施例并从中导出其他实施例，使得可以在不脱离本发明范围的情况下进行结构的和逻辑的替换和更改。因此，详细的描述并不应被视为具有限制意义，且各实施例的范围仅通过附属权利要求以及这些权利要求所赋予的等同概念的全部范围来进行限定。
如本文所采用的，词语“或”、“或者”可以以包含性或排他性的含义来解释。此外，多个例子还可作为单个例子用于其中描述的资源、操作或结构。此外，不同资源、操作、引擎和数据保存之间的边界是任意的，且特定操作在特定说明性配置的环境下被阐述。功能的其他配置也是可以预期的，并且其落入本发明的各个实施例的范围内。通常，在示例性配置中作为独立资源呈现的结构和功能可作为组合的结构或资源以实施应用。类似地，作为单个资源呈现的结构和功能可作为单独资源以实施应用。如附属权利要求所述的这些及其他变型、修改、添加和改善均属于本发明实施例的范围内。相应地，说明书和附图均是用于解释说明，而不具有限制意义。
除非另有说明，条件性语词，例如尤其是“可以”、“可能”、“可能会”或“可”或本文中采用的其他作此理解的词语，通常旨在表达某些实施例包括某些特征、元件和/或步骤，而其他实施例不包括。因此，此类条件性语词通常并不表示特征、元件和/或步骤必须要以任何方式用于一个或多个实施例，或一个或多个实施例必须要包括决定这些特征、元件和/或步骤是否要被纳入或者是否在任何特定的实施例中实施的逻辑，而不论具有或不具有用户输入或提示。

Claims (30)

  1. 一种波导器件，包括第一表面、第二表面、第四表面和光吸收材料层，其中：
    所述第一表面包括第一光栅结构；
    所述波导器件构造为引导耦合入光束在第一表面和第二表面之间进行全内反射；
    第一光栅结构构造为干扰全内反射以使得至少部分耦合入光束从波导器件耦合出来并从第一表面投射出去，从波导器件耦合出的这部分耦合入光束形成耦合出光束；
    所述耦合入光束经全内反射后的其余部分到达第四表面；及
    所述光吸收材料层与第二表面平行且通过间隙与第二表面隔离。
  2. 根据权利要求1所述的波导器件，其中：
    所述耦合出光束从第一表面会聚形成直立光锥，然后发散以在直立光锥的上方形成倒立光锥；及
    所述直立或倒立光锥与第一表面平行的截面包括与耦合出光束对应的点阵。
  3. 根据权利要求1所述的波导器件，其中：
    所述耦合出光束从第一表面发散形成倒立光锥；及
    所述倒立光束与第一表面平行的截面包括与耦合出光束对应的点阵。
  4. 根据权利要求1所述的波导器件，其中：
    所述第一表面为x-y平面；
    所述耦合入光束基本上沿着x-y平面的x轴方向在波导器件内传播；
    所述耦合出光束基本上沿着与x-y平面正交的z轴方向传播；
    所述第一光栅结构以相应的(x，y)位置分布在x-y平面内；
    第一光栅结构与光栅深度、占空比、周期和在x-y平面内相对于z轴方向的方向相关联；
    在x轴方向上不同位置的第一光栅结构具有不同的光栅深度和不同的光栅占空比的至少其中之一；
    在x轴方向上不同位置的第一光栅结构具有不同的周期；及
    在y轴方向上不同位置的第一光栅结构具有不同的方向。
  5. 根据权利要求1所述的波导器件，其中：
    所述波导器件为平面波导；
    所述第一表面和第二表面相互平行且为平面波导的最大表面；及
    所述耦合出光束自第一表面从波导器件中耦合出来。
  6. 根据权利要求1所述的波导器件，其中：
    所述波导器件为平面波导；
    所述第一表面和第二表面相互平行且为平面波导的最大表面；
    所述第一光栅结构包括设在第一表面和第二表面之间的体光栅；及
    所述耦合出光束自第一表面从波导器件中耦合出来。
  7. 根据权利要求1所述波导器件，进一步包括与第四表面相对的长形第三表面，其中：
    光源通过第三表面将光耦合进入波导器件，形成耦合入光束；及
    来自光源的光准直成与所述长形第三表面对应的线形。
  8. 根据权利要求1所述的波导器件，其中：
    所述第四表面包括另一光吸收材料层，用于吸收耦合入光束的其余部分。
  9. 根据权利要求1所述波导器件，进一步包括第二光栅结构，所述第二光栅结构设在第一表面或第二表面中的至少一个表面上，其中：
    光源通过所述第二光栅结构将光耦合进入波导器件，形成耦合入光束。
  10. 根据权利要求1所述的波导器件，其中：
    光吸收材料层为着色阳极氧化铝层。
  11. 一种光投射系统，包括
    波导器件，所述波导器件包括第一表面、第二表面、第四表面和光吸收材料层，所述第一表面包括第一光栅结构；和
    光源，所述光源将光耦合进入波导器件以形成耦合入的光束，其中：
    所述波导器件构造为引导耦合入的光束在第一表面和第二表面之间进 行全内反射；
    所述第一光栅结构构造为干扰全内反射以使得至少部分耦合入光束从波导器件耦合出来并从第一表面投射出去，从波导器件耦合出的这部分耦合入光束形成耦合出光束；
    所述耦合入光束经全内反射后的其余部分到达第四表面；及
    所述光吸收材料层与第二表面平行且与第二表面有间隔。
  12. 根据权利要求11所述光投射系统，其中：
    所述耦合出光束从第一表面发散形成倒立光锥；及
    所述倒立光锥与第一表面平行的截面包括与耦合出光束对应的点阵。
  13. 根据权利要求11所述光投射系统，其中：
    所述耦合出光束从第一表面会聚形成直立光锥，然后发散以在直立光锥的上方形成倒立光锥；及
    所述直立光锥或倒立光锥与第一表面平行的截面包括与耦合出光束对应的点阵。
  14. 根据权利要求11所述光投射系统，其中：
    所述第一表面为x-y平面；
    所述耦合入光束基本上沿着x-y平面的x轴方向在波导器件内传播；
    所述耦合出光束基本上沿着与x-y平面正交的z轴方向传播；
    所述第一光栅结构以相应的(x，y)位置分布在x-y平面内；
    第一光栅结构与光栅深度、占空比、周期和在x-y平面内相对于z轴方向的方向相关联；
    在x轴方向上不同位置的第一光栅结构具有不同的光栅深度和不同的光栅占空比的至少其中之一；
    在x轴方向上不同位置的第一光栅结构具有不同的周期；及
    在y轴方向上不同位置的第一光栅结构具有不同的方向。
  15. 根据权利要求11所述光投射系统，其中：
    所述波导器件为平面波导；
    所述第一表面和第二表面相互平行且为平面波导的最大表面；及
    所述耦合出光束自第一表面从波导器件中耦合出来。
  16. 根据权利要求11所述光投射系统，其中：
    所述波导器件为平面波导；
    所述第一表面和第二表面相互平行且为平面波导的最大表面；
    所述第一光栅结构包括设在第一表面和第二表面之间的体光栅；及
    所述耦合出光束自第一表面从波导器件中耦合出来。
  17. 根据权利要求11所述光投射系统，其中：
    所述波导器件进一步包括与第四表面相对的长形第三表面；
    所述光源通过第三表面将光耦合进入波导器件，形成耦合入光束；及
    来自光源的光准直成与所述长形第三表面对应的线形。
  18. 根据权利要求11所述光投射系统，其中：
    所述第四表面包括另一光吸收材料层，用于吸收耦合入光束的其余部分。
  19. 根据权利要求11所述光投射系统，其中：
    所述波导器件进一步包括第二光栅结构，所述第二光栅结构设在第一表面或第二表面中的至少一个表面上；及
    所述光源通过所述第二光栅结构将光耦合进入波导器件，形成耦合入光束。
  20. 根据权利要求11所述光投射系统，其中：
    光吸收材料层为着色阳极氧化铝层。
  21. 根据权利要求11所述光投射系统，进一步包括：
    检测器，所述检测器构造为用来接收远处物体在多个位置对耦合出光束的反射，以测定所述多个位置相对于光投射系统的距离。
  22. 一种波导器件，包括第一表面和第二表面，其中：
    所述第一表面包括第一光栅结构；
    所述波导器件构造为引导耦合入光束在第一表面和第二表面之间进行全内反射；及
    所述第一光栅结构构造为干扰全内反射以使得至少部分耦合入光束从 波导器件耦合出来并从第一表面投射出去，从波导器件耦合出的这部分耦合入光束形成耦合出光束，所述耦合出光束配置为在耦合出光束投射的表面上形成点阵。
  23. 根据权利要求22所述波导器件，进一步包括第四表面，其中：
    所述耦合入光束经全内反射后的其余部分到达第四表面；及
    所述第四表面包括第一光吸收材料层，用于吸收耦合入光束的其余部分。
  24. 根据权利要求23所述波导器件，进一步包括第二光吸收材料层，其中：
    所述第二光吸收材料层与第二表面平行且与第二表面有间隔。
  25. 根据权利要求22所述的波导器件，其中：
    所述耦合出光束从第一表面会聚形成直立光锥，然后发散以在直立光锥的上方形成倒立光锥；及
    所述直立或倒立光锥与第一表面平行的截面包括与耦合出光束对应的点阵。
  26. 根据权利要求22所述的波导器件，其中：
    所述耦合出光束从第一表面发散形成倒立光锥；及
    所述倒立光锥与第一表面平行的截面包括与耦合出光束对应的点阵。
  27. 根据权利要求22所述的波导器件，其中：
    所述第一表面为x-y平面；
    所述耦合入光束基本上沿着x-y平面的x轴方向在波导器件内传播；及
    所述耦合出光束基本上沿着与x-y平面正交的z轴方向传播。
  28. 根据权利要求27所述的波导器件，其中：
    所述第一光栅结构与光栅深度和占空比相关联；及
    在x轴方向上不同位置的第一光栅结构具有不同的光栅深度和不同的光栅占空比其中至少一种。
  29. 根据权利要求27所述的波导器件，其中：
    所述第一光栅结构与周期相关联；及
    在x轴方向上不同位置的第一光栅结构具有不同的周期。
  30. 根据权利要求27所述的波导器件，其中：
    所述第一光栅结构与在x-y平面内相对于z轴方向的方向相关联；及
    在y轴方向上不同位置处的第一光栅结构具有不同的方向。
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