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WO2021062941A1 - 基于光栅的光波导光场显示系统 - Google Patents

基于光栅的光波导光场显示系统 Download PDF

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Publication number
WO2021062941A1
WO2021062941A1 PCT/CN2019/124230 CN2019124230W WO2021062941A1 WO 2021062941 A1 WO2021062941 A1 WO 2021062941A1 CN 2019124230 W CN2019124230 W CN 2019124230W WO 2021062941 A1 WO2021062941 A1 WO 2021062941A1
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Prior art keywords
light
optical waveguide
pixel
grating
projection
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PCT/CN2019/124230
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English (en)
French (fr)
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刘立林
滕东东
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中山大学
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Publication of WO2021062941A1 publication Critical patent/WO2021062941A1/zh

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    • 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
    • G02B27/01—Head-up displays
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B30/00—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images
    • G02B30/20—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes
    • G02B30/26—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes of the autostereoscopic type
    • G02B30/27—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes of the autostereoscopic type involving lenticular arrays
    • 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
    • G03B35/00—Stereoscopic photography
    • G03B35/18—Stereoscopic photography by simultaneous viewing
    • G03B35/24—Stereoscopic photography by simultaneous viewing using apertured or refractive resolving means on screens or between screen and eye

Definitions

  • the invention relates to the field of three-dimensional display technology, and more particularly to a grating-based optical waveguide light field display system.
  • optical waveguides are currently a hot option when developing optical engines with cutting-edge 3D display technology.
  • thin and light three-dimensional glasses based on optical waveguide structures are becoming more and more widely used.
  • the existing optical waveguide three-dimensional display system is mainly based on the stereoscopic technology, by projecting only one view to the observer's binoculars, and using the convergence of the binoculars in space to realize the presentation of three-dimensional depth.
  • the observer needs to focus his/her eyes on the display surface. The resulting focus-convergence conflict is inconsistent with the natural physiological response of the human eye when observing a real three-dimensional space scene.
  • the human eye When observing a real object naturally, the human eye receives a cone-shaped light beam from a real object point.
  • the cone-shaped light beam makes the observer’s eyes converge on the object point while also allowing the observer’s eyes to naturally focus on the object point.
  • the focus-convergence conflict that stereoscopic technology inherently contradicts the natural physiological requirements of the human body is the main cause of visual fatigue when viewing three-dimensional movies.
  • the present invention provides the following solutions.
  • Optical waveguide light field display system based on grating including:
  • the stack structure of light-splitting characteristic light-guide projection units is composed of a stack of M light-splitting characteristic light-guide projection units.
  • Each light-splitting characteristic light-guide projection unit projects a virtual image in the +z direction, and propagates the projected virtual image in the -z direction through its coupling out pupil.
  • the presented light information where M ⁇ 1;
  • the light-splitting characteristic optical waveguide projection unit includes: a pixel array, which is used to load optical information and emit light beams; a light-splitting grating, which is composed of grating units, and is placed in front of the pixel array along the transmission direction of the light-emitting beam of the pixel array , Regulate the transmission direction of the light beam emitted by each pixel of the pixel array after passing through the corresponding grating unit, and restrict its exit angle, the light splitting grating and the pixel array form a pixel array-light splitting grating pair; optical waveguide, the optical waveguide is composed of a substrate and total reflection Surface composition, transmitting the incident light beam through total reflection; optical coupling device, coupling incident light into the optical waveguide; relay device, the relay device is placed between the light-splitting grating and the optical coupling device, guiding each pixel of the pixel array through the corresponding grating
  • the control unit controls each pixel of the pixel array to load its corresponding information, wherein the corresponding information of any pixel is the reverse of the target scene along the virtual image of the pixel corresponding to the pixel, and the direction of propagation of the equivalent outgoing beam on the virtual image of the pixel. Projection information
  • the grating-based optical waveguide light field display system is configured to be able to project view information from at least two or more basic pixel sets or/and synthetic pixel sets to the pupil of the observer, and the exit angle is restricted by the beam splitting grating
  • the light beam emitted by each pixel of, when it enters the pupil of the observer, its spatial size is smaller than the pupil size;
  • the basic pixel set is defined as follows: when a light-guide projection unit with light-splitting characteristics of a one-dimensional grating is used, the light emitted by each pixel of its pixel array will be guided to N groups of pixels in N viewing zones based on the grating light-splitting, as N When using a two-dimensional grating optical waveguide projection unit with light-splitting characteristics, the grating unit corresponds to a pixel group containing N pixels, and the pixels with the same relative arrangement positions are grouped as N basic pixel sets. N ⁇ 2;
  • the synthetic pixel set is defined as follows: it is formed by combining pixels in one region of different basic pixel sets, and the pixel virtual image of each pixel of the synthetic pixel set is distributed throughout the virtual image distribution area of the pixel array.
  • the light-splitting characteristic optical waveguide projection unit further includes an image plane projector, or/and a compensation unit
  • the image projection device is placed in front of the exit pupil of the coupling light along the light beam transmission direction, and the light beams from different pixels of the pixel array guided by the light coupling device are reversely converged on the new projection surface.
  • the new pixel array virtual image of the pixel array on the projection surface is constructed, and the exit pupil of the coupled light exit pupil is the equivalent exit beam of each new pixel virtual image on the new pixel array virtual image, and the new projection surface ,
  • the new pixel virtual image and the new pixel array virtual image replace the projection surface, pixel virtual image, and pixel array virtual image when the image surface projector is not introduced, as the actual projection surface, pixel virtual image, and pixel array virtual image when the image surface projector is introduced;
  • the compensation unit is placed after the optical coupling out device along the -z direction, and is used to eliminate the influence of other devices in the optical waveguide projection unit with light splitting characteristics on the incident light from the external environment.
  • the light-splitting-characteristic light-guide projection unit couples out the light exit pupil through the light-guide and exits each light beam as parallel light, and the position of the virtual image of the pixel array corresponds to +z infinity.
  • some pixels corresponding to the grating unit of the two-dimensional grating are missing due to the shape of the pixel array arrangement area, and when it is less than M, the missing pixels are replaced with non-luminous virtual pixels.
  • the light-splitting characteristic light guide projection unit is provided with a diaphragm for blocking the light emitted from each pixel of the pixel array through the non-corresponding grating unit.
  • the stacked optical waveguide projection units with spectral characteristics share the image plane projection device or/and the compensation unit.
  • the pixel array is an OLED microdisplay, an LED microdisplay, an LCOS microdisplay, or a reflective surface that reflects externally projected information
  • the optical waveguide is a flat or curved optical waveguide
  • the light coupling-in device is micromachined
  • the relay device is a collimating lens, Or/and imaging lens, or/and beam deflector
  • the light out-coupling device is a microstructure grating etched on the optical waveguide, or processed on the reflective surface of the optical waveguide, or exposed to the holographic grating of the optical waveguide.
  • the image projection device is a single lens or a combined lens, or a holographic grating exposed to an optical waveguide, or a microstructure grating etched on an optical waveguide, and the compensation unit is a phase film or a microstructure grating.
  • the compensation unit is attached to the optical waveguide, or etched on the optical waveguide, or exposed to the optical waveguide.
  • the light-splitting characteristic light guide projection unit is formed by stacking two or more monochromatic light-splitting characteristic light guide projection units, and the two or more monochromatic light-splitting characteristic light guide projection units project light information at different wavelengths.
  • the projected virtual images of different wavelengths are mixed and synthesized into a color virtual image.
  • the light-splitting characteristic light guide projection unit is formed by stacking two or more light-splitting characteristic light-guide projection units with small viewing angles, and the virtual image coverage of the pixel array projected by the light-splitting characteristic light guide projection units of each small viewing angle is combined and expanded.
  • the small viewing angle light-splitting characteristic optical waveguide projection unit has the same optical structure as the light-splitting characteristic optical waveguide projection unit, and the two or more small viewing angle light-splitting characteristic optical waveguide projection units cover the viewing area of the virtual image of the pixel array. Dislocation distribution, by combining the dislocation viewing area distribution, the two or more small viewing angle light-splitting characteristic light guide projection units are stacked, and the component light characteristic light-guide projection unit projection information covers the viewing area relative to a small viewing angle light-splitting characteristic light The case of the waveguide projection unit has been expanded.
  • the one-dimensional beam splitting grating is a cylindrical lens grating or a slit grating
  • the two-dimensional beam splitting grating is a micro lens array.
  • the pixel array-spectroscopic grating pair has orthogonal characteristics, adjacent grating units respectively allow mutually orthogonal light to pass through, and the optical characteristics of the light emitted by each grating unit corresponding to the pixel on the pixel array are consistent with the grating unit Optical properties that allow light to pass through.
  • the orthogonal characteristic may be linear polarization, left-right rotation polarization characteristics, or non-simultaneous timing characteristics, or a combination of the polarization characteristics and the timing characteristics.
  • each pixel when the light beam emitted by each pixel exits the optical waveguide through the optical coupling-out device, it is emitted through the optical coupling-out device twice or more at a large interval.
  • the large spacing allows two adjacent outgoing beams from the same pixel to be observed during observation.
  • the spatial distance between the eyes of the person is greater than the pupil diameter of the eye.
  • the system further includes an observer pupil tracking feedback device for tracking the pupil position of the observer and feeding it back to the control unit.
  • the control unit loads pixels that emit light beams twice or more at a large interval through the optical coupling device in real time.
  • the outgoing light beam of the target scene that enters the pupil of the observer is opposite to the projection information on the projection surface.
  • Gratings are commonly used optical devices in the traditional three-dimensional display field. Light splitting through gratings, such as one-dimensional cylindrical lens gratings or one-dimensional slit gratings, to project different view information to different viewing areas; or directly through gratings, such as two-dimensional microlens arrays, to project beam distributions in different spatial sagittal directions to the observer, superimposing Form a spatial light distribution.
  • gratings such as one-dimensional cylindrical lens gratings or one-dimensional slit gratings, to project different view information to different viewing areas; or directly through gratings, such as two-dimensional microlens arrays, to project beam distributions in different spatial sagittal directions to the observer, superimposing Form a spatial light distribution.
  • the present invention introduces a grating into the optical waveguide structure, and on the basis of using the grating splitting function to generate multiple views, the grating restricts the exit angle of the light beam emitted by each pixel, and guides the small divergence angle of two or more views through the optical waveguide
  • the light beam or the parallel narrow/thin light beam enters each eye of the observer, and based on the spatial superposition, the spatial light field distribution that the observer's eye can focus naturally is formed.
  • the present invention utilizes at least one light-splitting characteristic optical waveguide projection unit stacking to project an image to a finite or infinite projection surface to construct a light field display system.
  • Each light-splitting characteristic optical waveguide projection unit includes a pixel array as a display device, a light-splitting grating, an optical waveguide, and other components.
  • Each basic pixel set constituting the pixel array, the light emitted by the pixel passes through the light splitting grating, and the output angle is limited to propagate along each specific vector direction, and is guided by the optical waveguide and related components in the form of a small divergence beam or a parallel narrow/thin beam The eyes.
  • Different view information from different basic pixel sets of the at least one light-splitting optical waveguide projection unit is incident on the pupil of the observer, and the different sagittal beams are spatially superimposed to form a three-dimensional spatial light field in which the observer's eyes can naturally focus.
  • a grating-based optical waveguide light field display system of the present invention realizes monocular multi-view by means of gratings, which overcomes the inherent focus-convergence conflict problem of traditional optical waveguide displays; and is based on optical waveguides, Design a display engine with a thin and light structure so that it can be applied to various screens and portable display terminals, such as head-mounted VR, AR, mobile phones, iPads, etc.
  • Fig. 1 is a schematic diagram of the optical structure of an optical waveguide projection unit with spectral characteristics.
  • Fig. 2 is a schematic diagram of the first implementation example of a single-lens multi-view of the optical waveguide projection unit with spectral characteristics.
  • Fig. 3 is a schematic diagram of a second implementation example of a single-lens multi-view of the optical waveguide projection unit with spectral characteristics.
  • Fig. 4 is a schematic diagram of the third implementation example of the monocular multi-view of the optical waveguide projection unit with spectral characteristics.
  • Fig. 5 is a schematic diagram of the implementation example 4 of the monocular multi-view of the optical waveguide projection unit with spectral characteristics.
  • Fig. 6 is a schematic diagram showing that the pupil of the observer cannot completely cover all the beam distribution areas from a basic view.
  • FIG. 7 is a schematic diagram of the first example of monocular multi-synthesis view realized by stacking optical waveguide projection units with light splitting characteristics.
  • FIG. 8 is a schematic diagram of the second example of a monocular multi-synthesized view realized by a stacked light-guide projection unit with light-distribution characteristics.
  • FIG. 9 is a schematic diagram of viewpoint uncertainty caused by different reflection times of light beams from the same pixel.
  • FIG. 10 is a schematic diagram of the equivalent outgoing beam distribution of the virtual image of each pixel in the basic pixel set g.
  • FIG. 11 is a schematic diagram of the equivalent outgoing beam distribution of the virtual image of each pixel in the basic pixel set j.
  • Fig. 12 is a schematic diagram of a large-spaced secondary emission of light beams from the same pixel.
  • FIG. 13 is a schematic diagram of the virtual image stitching of the projection pixel array of the light-guide projection unit with the small view distinguishing light characteristics.
  • Fig. 14 is a schematic diagram of the structure of a pair of orthogonal characteristic pixel array and light-splitting grating.
  • the optical waveguide light field display system based on the grating of the present invention uses a stack structure of optical waveguide projection units with spectral characteristics as the optical information projection structure, and guides the different view information coupled by each optical waveguide projection unit to the pupil of the observer, which comes from different views.
  • the small divergence angle beams or the spatial superposition of parallel narrow/small beams form a spatial light field presentation that the observer’s eyes can naturally focus.
  • the present invention realizes a thin and light structure through a film-like optical waveguide, and projects multiple views with the aid of a grating. Through the combination of the two, a thin and light optical structure is used to overcome focus-convergence. conflicting light field display.
  • Figure 1 shows an optical waveguide projection unit with spectral characteristics including a grating. It mainly includes a pixel array 1011, a light splitting grating 1012, a relay device 1013, an optical coupling-in device 1014, an optical waveguide 1015, an optical coupling-out device 1016, an image projection device 1017, a compensation unit 1018, and a control unit 20.
  • the pixel array 1011 is composed of an arrangement of pixels that can load light information, which can be an OLED microdisplay, an LED microdisplay, an LCOS microdisplay, or a reflective surface that reflects external projection information, loads the light information synchronously, and emits light beams.
  • the emitted light is split by the light splitting grating 1012, and propagates to different sagittal directions at a limited exit angle.
  • the pixel array 1011 and the light-splitting grating 1012 form a pixel array-light-splitting grating pair.
  • the optical waveguide 1015 is a two-dimensional optical waveguide, such as a planar optical waveguide or a curved optical waveguide, which is composed of a substrate, a reflective surface 1015a and a reflective surface 1015b, and transmits the incident light beam through total reflection.
  • the optical coupling device 1014 couples incident light into the optical waveguide 1015, which can be a microstructure grating etched on the optical waveguide by a micromachining process, or a holographic grating exposed on the optical waveguide, or a mirror coated on the optical waveguide, or Diffraction grating attached to the optical waveguide.
  • the optical waveguide 1015 can be a microstructure grating etched on the optical waveguide by a micromachining process, or a holographic grating exposed on the optical waveguide, or a mirror coated on the optical waveguide, or Diffraction grating attached to the optical waveguide.
  • the relay device 1013 is placed between the pixel array-light-splitting grating pair and the light coupling device 1014, and can be a collimating lens, collimating the light beams emitted by each pixel of the pixel array 1011, and pulling the collimated light beams into the light coupling device 1014, It can also be a reflective imaging device, which images the pixel array 1011 and guides its beam to enter the light coupling device 1014, or a deflecting mirror that reflects the emitted light from the pixel array 1011 into the light coupling device 1014, or the above A combination of various devices.
  • the light coupling-out device 1016 is an embossed optical element etched on the optical waveguide, or etched on the reflective surface of the optical waveguide through a micromachining process, or exposed to the holographic grating of the optical waveguide, modulating and guiding the optical waveguide 1015 to totally reflect and propagate over The light turns to the exit pupil 1019 for coupling out light.
  • the out-coupling light exit pupil 1019 is represented by a dashed line to distinguish it from the reflective surfaces 1015a and 1015b.
  • the light beams from different pixels of the pixel array 1011 are guided to the entrance and exit pupils 1019, and then pass through the image projection device 1017 to form a virtual image of the pixels on the projection surface 30 in the +z direction, forming the pixels of the pixel array 1011 on the projection surface 30 Array virtual image 1011'.
  • the image projection device 1017 may be a lens, or an optical device such as a diffraction grating.
  • a common situation is that the collimated light beams from different pixels of the pixel array 1011 maintain the collimated light state, and guide the entrance and exit pupils 1019 to the -z direction at respective corresponding angles, and then pass through the image projection device 1017 to +z
  • the virtual images of the respective corresponding pixels converge on the projection surface 30 to form a virtual pixel array image 1011 ′ of the pixel array 1101 on the projection surface 30.
  • the light beam exiting from the exit pupil of the coupling light is equivalent to the equivalent exit light beam from the virtual image of each pixel of the pixel array virtual image 1011'.
  • the light emitted from each pixel on the pixel array 1011 exits the light splitting grating 1012 at a small exit angle, and then is pulled by other components, and finally the equivalent output light is transmitted to the pupil of the observer at the small exit angle of the virtual image of each pixel. your region.
  • the light beams bt and b t+1 from the pixel virtual images p′ t and p′ t+1 have small exit angles.
  • p′ t and p′ t+1 are the virtual image of the pixels p t and p t+1.
  • the requirement for the quantization value of the small exit angle is that when the light beam with the small exit angle equivalently emitted from the virtual image of each pixel reaches the observer's eye, its coverage area cannot be larger than the pupil size of the eye.
  • the image projection device 1017 can also be removed from FIG. 1. At this time, the beams b t and b t+1 are parallel narrow beams with small sizes along the x direction, and the corresponding projection surface 30 is placed at infinity in the +z direction. Place.
  • the requirement for the quantization value of the size of the narrow light beam is that when the narrow light beam equivalently emitted from the virtual image of each pixel reaches the observer's eye, its coverage area cannot be larger than the pupil size of the eye.
  • the light emitted by different pixels of the pixel array 1011 can also project the corresponding virtual image of the pixel to infinity in the +z direction with the image projection device 1017 removed, or non-parallel light after the light splitting grating 1012 and the relay device 1013 , And then guided by the optical waveguide 1015 and other devices, virtually converge on the +z-direction finite-distance projection surface 30 respectively corresponding to the virtual image of the pixel.
  • the compensation unit 1018 is placed along the -z direction after the optical coupling-out device, which is used to reversely eliminate the influence of other components of the optical waveguide projection unit on the incident light from the external environment, so as to realize the superimposition and fusion between the displayed scene and the external real scene. Often required for augmented reality AR.
  • the compensation unit may be a phase film, or a solid lens, or a microstructure grating.
  • the compensation unit is attached to the optical waveguide, or etched on the optical waveguide, or exposed to the optical waveguide. In the optical structure shown in FIG. 1, the compensation unit 1018 can also be removed as needed, for example, when the image projection device 1017 is removed and other devices have no additional influence on the incident light from the external environment.
  • the compensation unit 1018 can be replaced by an additional light shielding device, such as a light shielding film.
  • an additional light shielding device such as a light shielding film.
  • the relay device 1013 is embodied as a collimating lens, which converts the light emitted by each pixel of the pixel array 1011 into parallel light beams with different propagation directions.
  • the optical coupling device 1014 is embodied as a holographic grating exposed to the optical waveguide 1015, and the light beams of different propagation directions input through the relay device 1013 are coupled into the optical waveguide 1015, so that each light beam after the coupling is in the optical waveguide 1015.
  • the inside 1015 propagates to the optical coupling-out device 1016 through total reflection.
  • the out-coupling light device 1016 is embodied as a holographic grating exposed to the diaphragm, and deflects the incident light propagation direction to the out-coupling light exit pupil 1019 in the -z direction.
  • the -z-direction and the x-direction indicate a vertical relationship.
  • the two may also have a non-vertical relationship.
  • the light beam transmitted along the x direction is modulated by the optical coupling-out device 1016 and transmitted along the -z direction that is non-perpendicular to the x.
  • the image projection device 1017 in FIG. 1 is embodied as a concave lens, which transmits parallel light beams from each pixel of the pixel array 1101 and converges on the virtual image of the corresponding pixel on the projection surface 30 in the +z direction.
  • the compensation unit 1018 is embodied as a relief grating device.
  • FIG. 2 shows different converging points formed by the light emitted from the pixel array 1011 through the light splitting grating 1012 and splitting the light.
  • the emitted light of pixels p1, p4, ... converges at the convergence point VR11 and then continues to propagate to the relay device 1013
  • the output light of pixels p2, p5, ... converges at
  • the convergence point VR12 it continues to propagate to the relay device 1013
  • the emitted light of the pixels p3, p6, ... converges at the convergence point VR13 and then continues to propagate to the relay device 1013.
  • the pixels corresponding to each convergence point respectively constitute a basic pixel set.
  • the relay device 1013, the coupling device 1014, the optical waveguide 1015, the coupling device 1016, and the image projection device 1017 the emitted light of the basic pixel set ⁇ p1, p4,... ⁇ again converges on the viewpoint V11, the basic pixel set ⁇
  • the emitted light of p2, p5,... ⁇ converges at the viewpoint V12 again, and the emitted light of the basic pixel set ⁇ p3, p6,... ⁇ converges at the viewpoint V13 again.
  • the virtual image composition of a basic pixel set corresponds to the virtual image of the basic pixel set.
  • a basic pixel set loading information that is, the information displayed on the virtual image corresponding to the basic pixel set, is named the basic view loaded by the basic pixel set corresponding to the basic pixel set virtual image, and the corresponding viewpoints are V11, V12, and V13, respectively.
  • M s1 and M s1 are the edge points of the distribution area of the pixel array virtual image 1011 ′ on the projection surface 30. Due to the difference of the corresponding pixels, the distribution areas of the virtual images of different basic pixel sets on the projection surface 30 are offset, and the offset is the same order of magnitude as the pixel virtual image pitch. This offset is ignored below, and the difference between the virtual image distribution area of each basic pixel set and the virtual image distribution area of its corresponding pixel array is no longer distinguished.
  • each basic pixel set is loaded with the corresponding basic view, and based on the spatial superposition of the beams emitted from these views, a spatial light distribution that the eye can naturally focus on is formed, and a light field display is realized.
  • a1 (L ⁇ da)/(L+v)
  • c1
  • is an absolute value sign.
  • the basic view corresponding to each basic pixel set is loaded by the control unit 20.
  • the view information corresponding to any one pixel is the projection information of the target scene on the virtual image of the pixel in the opposite direction of the equivalent outgoing light propagation direction of the virtual image of the pixel corresponding to the pixel.
  • its loading information is the projection information of the scene along the light beam b t opposite to the virtual pixel image p′ t.
  • the basic view loaded by each basic pixel set is the view of the target scene on the virtual image of the corresponding basic pixel set with respect to its corresponding viewpoint.
  • Fig. 2 along the -z direction, the pupil 40 of the observer is located behind the plane where the viewpoint is located, and v takes a positive value at this time.
  • Fig. 3 shows another situation. Along the -z direction, the pupil 40 of the observer is located in front of the plane where the viewpoint is located, and v takes a negative value at this time.
  • the optical structure shown in FIG. 2 and FIG. 3 can also remove the image projection device 1017.
  • the light emitted by each pixel through the coupled light exit pupil 1019 is a parallel light beam.
  • two or more views can be projected to the pupil 40 of the observer at a suitable position.
  • the view information corresponding to each pixel is loaded under the control of the control unit 20.
  • the view information corresponding to any pixel is the information projected to infinity in the opposite direction of the target scene along the parallel beam projected by the pixel to the observer's eyes.
  • c1 2
  • FIGS. 1, 2 and 3 the illustration of some components is omitted in FIGS. 4 and 5. Based on the description of FIGS. 1 to 3, the omission is easy to understand, and in the figures drawn in the following parts, some components will not be shown for the same reason, and the detailed description will not be repeated.
  • Figures 2 to 5 describe a light-splitting characteristic light-guide projection unit that combines a common light-guide projection structure and a light-splitting grating 1012.
  • the optical waveguide projection structure composed of various optical waveguides and accessories with the following functions can be combined with the spectroscopic grating 1012 as the spectroscopic characteristic optical waveguide projection unit in this application: through the spectroscopic grating 1012, the pixel array 1011 controls the output After the incident light is coupled into the optical waveguide 1015 and transmitted by the optical waveguide 1015, the virtual image of the pixel array 1011' is projected to the projection surface 30 in the +z direction with the help of other optical devices, and the virtual image of the pixel array is transmitted to the -z direction through the exit pupil of the coupled light.
  • the light beam incident on the optical waveguide 1015 is a parallel light beam, and then the virtual image of each pixel is formed by the image projection device 1017.
  • the virtual image of each pixel is equivalent to being projected to infinity.
  • the light beam entering the optical waveguide 1015 can also be a non-parallel beam, as long as the light emitted from each pixel controlled by the beam splitting grating 1012 is guided to the pupil 40 of the observer through the optical waveguide 1015 and other components, and its size is not larger than that of the observer.
  • the pupil 40 has a diameter, and light beams from two or more views can enter the pupil 40 of the observer.
  • the image projection device 1017 can be used to adjust the position of the projection surface 30 to a certain finite or infinite distance, or the image projection device can be removed. And in the above system, when the system device itself does not affect the incident light of the external environment, or the external environment light information is not needed, the compensation unit 1018 can be removed from the system.
  • More than one light-splitting characteristic light guide projection unit can be superimposed to construct a stack structure of light-splitting characteristic light guide projection unit as a grating-based light guide light field display system to project corresponding basic views to more viewpoints. More viewpoints can be used to increase the density of viewpoints, or/and increase the distribution area of viewpoints, so that more views enter the pupil of the observer, or/and provide a larger observation area for the pupil of the observer, that is, pupil dilation.
  • the grating-based optical waveguide light field display system formed by stacking the multiple light-splitting characteristic optical waveguide projection units can realize binocular light field presentation.
  • each binocular of the observer needs one optical waveguide optical field display system based on the grating as an eyepiece.
  • V3, V4, V5, and V6 are viewpoints.
  • J(J ⁇ 2) is the number of viewpoint groups
  • K(K ⁇ 2) is the number of viewpoints in each viewpoint group.
  • the viewpoints V1, V3, and V5 are one group
  • the corresponding viewpoints of the basic views from the optical waveguide projection units with different light splitting characteristics can be arranged alternately, or they can be arranged adjacent to each other.
  • the corresponding basic view loaded by each basic pixel set is the projection view of the target scene on the virtual image of the basic pixel set with respect to its corresponding viewpoint.
  • M s1 and M s2 are the edge points of the distribution range of the pixel array virtual image 1011 ′ or 1021 ′ of the pixel array 1011 or 1021 on the projection surface 30, and Me1 and Me2 are the edge points of the pupil 40 of the observer.
  • S1 is the intersection point between the line V1 and Me2 and the projection surface 30
  • S2 is the intersection point between the line V3 and Me1 and the projection surface 30
  • S3 is the intersection point between the line V3 and Me2 and the projection surface 30
  • S4 is the intersection point between V5 and M The intersection of the e1 line and the projection surface 30.
  • K′ 3 basic pixel sets corresponding to V1, V3, and V5, each part of the pixels, such as the virtual image from the basic pixel set corresponding to V1 , the pixel corresponding to the virtual image of the pixel in the range of M s1 S1, and the virtual image from the basic pixel set corresponding to V3 in S2S3
  • the pixels corresponding to the virtual image of the pixels in the range, the pixels corresponding to the virtual image of the virtual image from the basic pixel set corresponding to V5 and the virtual image of the pixel within the range of S4M s2 form a composite pixel set.
  • the virtual image of each pixel in the composite pixel set constitutes the virtual image of the corresponding composite pixel set.
  • the loaded information is named the composite view.
  • the basic pixel sets corresponding to V2, V4, and V6 are also required to be combined in the same way to form another synthetic pixel set, and another synthetic view is correspondingly projected to the pupil 40 of the observer.
  • the K′ viewpoints corresponding to the related K′ basic pixel sets are connected to the observer’s pupil 40, so as to seamlessly cover the virtual image area of the basic pixel set on the projection surface 30;
  • the opening angles of adjacent viewpoints to the pupil 40 of the observer are seamlessly connected to the area covered on the projection surface 30.
  • K′ K
  • the movable area which leads to a smaller observation area.
  • Designing larger values of M′, J, and K can provide a larger observation area for the pupil 40 of the observer, and even accommodate the observation areas of multiple observer eyes.
  • the basic pixel sets corresponding to viewpoints v2 and v4 can be combined to form a synthetic pixel set that meets the above requirements, and the basic pixel sets corresponding to viewpoints v3 and v5 are combined to form another one that meets the above requirements.
  • the viewpoints are equally spaced by default. If the viewpoints are not evenly spaced, according to the requirements of the above-mentioned single-lens multi-view, specific to the spacing of each viewpoint, replace the da in formula (1) or formula (2) and formula (3) with the corresponding specific viewpoint distance value, and the same is true Just do the above operations.
  • each light-splitting characteristic light-guide projection unit can share the image plane projection device 1017 and/or the compensation unit. 1018.
  • FIGS. 7 and 8 are illustrated by taking the projection surface 30 projected at a finite distance as an example, which is also applicable to the case where the projection surface 30 is projected at infinity. In this case, it is required that the coverage angle area of the virtual image of each synthetic pixel set to the pupil 40 of the observer is consistent with the opening angle of the virtual image of the basic pixel set to the pupil 40 of the observer.
  • each basic pixel set its corresponding virtual image of the basic pixel set on the projection surface 30 has a corresponding viewpoint.
  • the virtual image of each pixel that composes a virtual image of a basic pixel set may not have a common viewpoint.
  • the same basic pixel on the pixel array 1011 concentrates the two pixels outgoing beams 1 and 2, after passing through the light splitting grating 1012, passing through the common convergence point VRu, and then passing through the relay device 1013, the coupling device 1014, and entering the light beams.
  • the waveguide 1015 performs transmission based on total reflection.
  • the basic pixel set corresponds to the virtual image of each pixel and no longer has a common viewpoint.
  • the grating coupling-out device 1014 adopting the same periodic structure, its deflection angle to the incident beam at different angles is determined by the grating equation, which will cause the virtual image of the same basic pixel set to have unequal spacing between the virtual images of each pixel, and their equivalent outgoing light will not converge. From one point of view.
  • the corresponding pixel array-light splitting grating pair constitutes a basic integrated imaging structure, and each microlens corresponds to a pixel group containing N pixels, and the relative arrangement position in each pixel group The same pixels are grouped into groups to form N basic pixel sets of the pixel array 1011, where N ⁇ 2.
  • each pixel of a basic pixel set passes through the light-splitting grating 1012, and there is an uncommon convergence point.
  • the virtual image of the pixel may not have a common viewpoint.
  • some of the pixels corresponding to the grating unit are missing due to the shape of the pixel array arrangement area, and the missing pixels are replaced with non-luminous virtual pixels, so that each basic pixel set has the same number of pixels. Pixels.
  • each pixel in the basic pixel set does not have a common viewpoint
  • designing two or more basic pixel sets to emit light into the same pupil of the observer can also achieve monocular multi-view light field display.
  • Each pixel is loaded with information, which is the projection information of the virtual image of the pixel to be displayed on the virtual image of the pixel corresponding to the corresponding virtual image of the pixel.
  • the information loaded in the basic pixel set is also named a basic view, and the virtual image of each pixel corresponding to this basic view has no common viewpoint.
  • the composite pixel set is formed by combining two or more such basic pixel sets of pixels in each area, and the pixel virtual image of each pixel can be incident on the same pupil 40 of the observer.
  • the virtual image of each pixel of the basic pixel set g is equivalent to emitting light at the pupil 40 of the observer, which cannot be completely incident on the pupil 40 of the observer because of the distribution is too scattered.
  • the virtual pixel images of the basic pixel set g are only represented by a small number of numbers.
  • the virtual image of each pixel equivalently emits light at the pupil 40 of the observer, and cannot be completely incident on the pupil 40 of the observer because of the distribution is too scattered.
  • a partial pixel of each of the two can form a synthetic pixel set whose pixel virtual image distribution area is consistent with the virtual image distribution area of the basic pixel set.
  • the light emitted from each pixel of the synthetic pixel set can all enter the pupil 40 of the observer.
  • a composite pixel set composes the information loaded by the pixels, and is named the composite view loaded by the composite pixel set.
  • the basic pixel sets related to a synthetic pixel set can come from the same light-splitting characteristic optical waveguide projection unit, or from stacked light-splitting characteristic light-guide projection units.
  • More light-waveguide projection units stacked with more spectral characteristics can provide more composite pixel sets, provide the observer pupil 40 with more simultaneous reception of the composite view, or/and provide the observer with a larger observation area, that is, pupil dilation , And even allow two or more eyes to display multiple views at the same time.
  • FIG. 10 and FIG. 11 are an example in which the projection surface 30 is at a finite distance.
  • the related process is also applicable to the case where the projection surface 30 is projected at infinity.
  • the opening angle of the synthetic pixel set virtual image to the observer's pupil 40 is required to be consistent with the opening angle of the basic pixel set virtual image to the observer's pupil 40.
  • the light beams emitted by each pixel can also pass through the coupling out device 1016 to exit the coupling exit pupil 1019 twice or more.
  • the light beams from the same pixel are adjacent to the second exit coupling exit pupil 1019.
  • the spatial distance in the area where the observer’s pupil 40 is located, such as St and St+1 in Fig. 12, is greater than the size Dp of the observer’s pupil 40 to prevent the light information from the same pixel from being simultaneously in two or more sagittal directions. Enter the pupil 40 of the observer.
  • the coupling light exit pupil 1019 can be designed as a non-continuous combination of multiple sub coupling light exit pupils, so that the light beam whose transmission distance is less than Dp along the optical waveguide passes through multiple times under the condition of completing a total reflection. After the total reflection, it will shoot twice or more times.
  • the system needs an observer pupil tracking feedback device 50, as shown in Fig. 12, tracking and feedback of the observer’s pupil position, and the control unit 20 sends the feedback to the pixel.
  • Load information which is the projection information on the projection surface of the light beam that is incident on the observer’s pupil in the light beam emitted by the target scene along the pixel through the exit pupil 1019.
  • the light-splitting characteristic light guide projection unit may be formed by stacking two or more monochromatic light-splitting characteristic light guide projection units, and the two or more monochromatic light-splitting characteristic light guide projection units project light information. With different wavelengths, the projected virtual images of the pixel array of different wavelengths are mixed and synthesized into a color virtual image.
  • the light-splitting characteristic light-guide projection unit may also be formed by stacking two or more light-splitting characteristic light-guide projection units with small viewing angles, and the virtual image of the pixel array of the light-splitting characteristic light-guide projection unit of each small viewing angle is spliced and expanded, as shown in FIG.
  • the pixel array virtual images 1011a' and 1011b' from the light guide projection units with different small viewing angles and light splitting characteristics are joined together to form an expanded pixel array virtual image 1011', and the corresponding viewing angles are expanded.
  • the virtual pixel image on the area 1011a' is the virtual pixel image of the light-waveguide projection unit 1011a with the small viewing angle light-splitting characteristic
  • the virtual pixel image on the area 1011b' is the virtual pixel image of the light-guide projection unit 1011b with the small viewing angle light-splitting characteristic.
  • the compensation unit 1018 is not shown.
  • the light-splitting characteristic light guide projection unit may be provided with a diaphragm 60, as shown in FIG. 2, to block the noise caused by the emission of each pixel of the pixel array 1011 through the non-corresponding grating unit.
  • Another method to suppress the inherent noise of the grating beam splitting is to design an orthogonal characteristic pixel array-splitter grating pair, that is, the adjacent grating units pass through the attached orthogonal detection unit, and only allow the light with the orthogonal characteristic to pass through each other.
  • the cross detection unit constitutes the orthogonal detection device 80, and the orthogonal detection units 80a, 80b, 80c, ... in FIG. 14 constitute the orthogonal detection device 80.
  • each grating unit corresponding to the pixel on the pixel array 1011 are controlled by the orthogonal generating unit to make it consistent with the optical characteristics of the grating unit allowing light to pass through.
  • Each orthogonal generating unit constitutes an orthogonal generating device 90, as shown in FIG. 14 orthogonal generating units 90a, 90b, 90c, ... constitute an orthogonal detecting device 90.
  • Commonly used orthogonal characteristics can be linear polarization and left-right rotation polarization characteristics. In this case, it can be achieved by using a polarizer on each grating unit as an orthogonal detection unit.
  • the corresponding orthogonal generating unit may also be a polarizer, or through the production process of the pixel array 1011, the light emitted by the pixel directly has corresponding optical characteristics.
  • time multiplexing is also a commonly used orthogonal characteristic.
  • the switch timing controllable aperture placed on each grating unit as the orthogonal detection unit.
  • the orthogonal generation unit it can be the switch timing controllable aperture. It can also be achieved by directly using the control unit 20 to control the operation and non-operation of the corresponding pixel.
  • the core idea of the present invention is to use one or more light-splitting characteristic optical waveguide projection units to use its light-splitting grating to control the light splitting and the exit angle of each pixel of the pixel array, and to project two or more to the observer’s pupil through the optical waveguide.
  • the light emitted by each pixel propagates through the grating beam splitter and the optical waveguide, and enters the pupil of the observer with a small divergence beam or a narrow/fine parallel beam.
  • the size of the incident surface of the beam is not larger than the pupil diameter.
  • optical waveguide projection structures such as optical waveguide projection units designed with various optical coupling devices and other various relay devices, or optical components designed to divide the image when coupling in and perform image restoration when coupling out
  • the optical waveguide projection unit combined with the light splitting grating, can be used as an optical waveguide projection unit with light splitting characteristics to perform optical waveguide light field display based on gratings.
  • the system of the present invention can be further extended. For example, by designing image projection devices 1017 with different focusing capabilities, multiple projection surfaces can be formed at different depths, and then on the projection surface of each depth, based on The principle of the present invention presents a scene within a certain range near the depth, so as to increase the depth of field of the displayed scene.
  • a time-sequential adjustable focus image projector 1017 which forms multiple projection surfaces at different depths in time sequence, and the projection surface of each depth simultaneously presents a scene within a certain range near the depth based on the process of the present invention, Improve the depth of field of the display scene based on the visual retention effect. It is also possible to track the real-time convergence depth of the observer's binoculars, and then control only the projection surface where the depth is located or the projection surface near the depth, based on the process of the present invention to present the scene within a certain range near the depth.
  • the image plane projector 1017 with time sequence adjustable focus such as a liquid crystal lens with controllable focal length and time sequence, or a liquid crystal film group formed by superimposing multiple liquid crystals, wherein different liquid crystal film combinations have different focusing capabilities and are driven by time sequence
  • the combination of different liquid crystal panels realizes two or more projection surfaces.
  • the design concept of the present invention is not limited to this, and any insubstantial modifications made to the present invention using this concept also fall within the protection scope of the present invention.
  • the used spectroscopic grating is not limited to the one-dimensional lenticular grating, one-dimensional slit grating, and two-dimensional microlens array grating described above. Accordingly, all related embodiments fall within the protection scope of the present invention.

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Abstract

一种基于光栅的光波导光场显示系统，由至少一个向有限远或无限远投影面投射图像的分光特性光波导投影单元堆叠构建。各分光特性光波导投影单元包含：显示器件的像素阵列（1011）、分光光栅（1012）、光波导（1015）及其它组件。构成像素阵列（1011）的各基本像素集，其像素出射光经分光光栅（1012），出射角受限地沿各自特定矢向传播，并以小发散角光束或平行窄/细光束的形态被光波导（1015）及相关组件导向观察者眼睛。利用光栅分光实现不同矢向小发散角光束或平行窄/细光束的空间叠加，克服传统光波导显示固有的聚焦-会聚冲突问题；并借助于光波导，设计实现轻薄结构的显示引擎，使之可以应用于各种屏幕及便携式显示终端。

Description

基于光栅的光波导光场显示系统 技术领域
本发明涉及三维显示技术领域，更具体涉及一种基于光栅的光波导光场显示系统。
背景技术
因其结构体积的轻薄优势，光波导是目前前沿三维显示技术开发光学引擎时的热点选项。尤其在增强现实(AR)领域，基于光波导结构的轻薄三维眼镜，正受到越来越广泛的应用。但现有光波导三维显示系统，还主要是基于体视技术，通过向观察者双目分别仅投射一个视图，利用双目视向在空间的会聚，来实现三维深度的呈现。为了清晰地看到双目各自对应的视图，观察者需要将他/她的眼睛聚焦于显示面。由此产生的聚焦-会聚冲突，和人眼观察真实三维空间景物时的自然生理反应不一致。在自然观察真实物体的时候，人眼接收来自于真实物点的圆锥状光束，该圆锥状光束在使观察者双目视向会聚于该物点的同时，也使观察者眼睛自然聚焦于该物点。体视技术固有悖逆人体自然生理要求的聚焦-会聚冲突，是三维观影时视觉疲劳产生的主要原因。
发明内容
为了在基于轻薄光波导的光学结构中，利用光栅实现克服聚焦-汇聚冲突的光场三维显示，本发明提供如下方案。
基于光栅的光波导光场显示系统，包括：
分光特性光波导投影单元堆栈结构，由M个分光特性光波导投影单元堆叠构成，各分光特性光波导投影单元向+z向投射虚像，并通过其耦出光出瞳向-z向传播该投射虚像所呈现光信息,其中M≧1；
其中，分光特性光波导投影单元包括：像素阵列，该像素阵列用于加载光信息并出射光束；分光光栅，该分光光栅由光栅单元组成，沿所述像素阵列出射光束传输方向置于像素阵列前，调控像素阵列各像素经对应光栅单元后出射光束的传输方向，并约束其出射角，该分光光栅和所述像素阵列组成像素阵列-分光光栅对；光波导，该光波导由基体和全反射面组成，通过全反射传输入射光束；光耦入器件，将入射光耦入光波导；中继器件，该中继器件置于分光光栅和光耦入 器件之间，引导像素阵列各像素经对应光栅单元出射光束入射光耦入器件；光耦出器件，引导光波导全反射传播过来的来自像素阵列各像素的光束转向至耦出光出瞳，并出射光波导，其中经耦出光出瞳出射的来自于各像素的光束，沿其出射方向反向的虚会聚点，定义为该像素对应的像素虚像，该出射光束为该像素虚像的等效出射光，各像素对应像素虚像于投影面上构建像素阵列虚像；
控制单元，在各时间点，控制所述像素阵列各像素加载各自对应信息，其中任一像素对应信息为目标场景沿该像素对应像素虚像等效出射光束传播矢向的反向在该像素虚像上的投影信息；
所述基于光栅的光波导光场显示系统被设置为能够向观察者瞳孔投射来自至少两个或两个以上基本像素集的、或/和合成像素集的视图信息，且出射角受分光光栅约束的各像素出射光束，入射观察者瞳孔时其空间尺寸小于该瞳孔尺寸；
其中，所述基本像素集定义如下：当采用一维光栅的分光特性光波导投影单元时，其像素阵列各像素出射光基于光栅分光将被分别引导至N个视区的N组像素，作为N个基本像素集，当采用二维光栅的分光特性光波导投影单元时，光栅单元分别对应包含N个像素的像素组中，相对排列位置相同的像素分别成组，作为N个基本像素集，其中N≧2；
并且其中，所述合成像素集定义如下：由不同基本像素集各一个区域内像素拼合而成，该合成像素集各像素的像素虚像遍布像素阵列虚像分布区域。
优选地，所述分光特性光波导投影单元还包括像面投射器，或/和补偿单元
其中所述像面投射器件沿光束传输方向置于耦出光出瞳前，将光耦出器件引导来的、来自于像素阵列不同像素的光束，反向会聚于新的投影面上各自对应的新的像素虚像，构建像素阵列在投影面上的新的像素阵列虚像，所述经耦出光出瞳出射光束为该新的像素阵列虚像上各新的像素虚像等效出射光束，其中新的投影面、新的像素虚像、新的像素阵列虚像代替未引入像面投射器时的投影面、像素虚像、像素阵列虚像，作为引入像面投射器时的实际采用投影面、像素虚像、像素阵列虚像；所述补偿单元沿-z向置于光耦出器件后，用于消除分光特性光波导投影单元中的其它器件对外部环境入射光的影响。
优选地，所述分光特性光波导投影单元经光波导耦出光出瞳出射各光束为平行光，其像素阵列虚像位置对应+z向无穷远处。
优选地，所述分光特性光波导投影单元中，二维光栅的部分光栅单元对应像 素受像素阵列排列区域形状限制发生缺失而不足M时，缺失的像素以不发光的虚拟像素代替。
优选地，所述分光特性光波导投影单元中置有光阑，用于挡除像素阵列各像素经非对应光栅单元出射光。
优选地，堆叠的各分光特性光波导投影单元，共用像面投射器件或/和补偿单元。
优选地，所述像素阵列为OLED微显示器、LED微显示器、LCOS微显示器，或反射外部投射信息的反射面，所述光波导为平面或曲面光波导，所述光耦入器件是通过微加工工艺刻蚀于光波导的微结构光栅，或曝光于光波导内的全息光栅，或镀膜于光波导的反射镜，或附着于光波导表面的衍射光栅，所述中继器件为准直透镜，或/和成像透镜，或/和光束偏转器，所述光耦出器件为刻蚀于光波导的微结构光栅，或者加工于光波导的反射面，或者曝光于光波导的全息光栅。
优选地，所述像面投射器件为单透镜或组合透镜，或曝光于光波导的全息光栅，或刻蚀于光波导的微结构光栅，所述补偿单元为相位膜，或微结构光栅，该补偿单元附着光波导，或者刻蚀于光波导，或者曝光于光波导。
优选地，所述分光特性光波导投影单元由两个或更多个单色分光特性光波导投影单元堆栈而成，该两个或更多个单色分光特性光波导投影单元投射光信息波长不同，所投射不同波长的虚像混光合成为彩色虚像。
优选地，所述分光特性光波导投影单元为由两个或更多个小视角分光特性光波导投影单元堆栈而成，各小视角分光特性光波导投影单元所投射像素阵列虚像覆盖视角拼合，扩展分光特性光波导投影单元投射信息所覆盖视角，
其中所述小视角分光特性光波导投影单元具有和所述分光特性光波导投影单元相同的光学结构，且该两个或多个小视角分光特性光波导投影单元所投射像素阵列虚像的覆盖视区错位分布，通过该错位视区分布的拼合，使该两个或多个小视角分光特性光波导投影单元堆栈而成分光特性光波导投影单元投射信息所覆盖视区相对于一个小视角分光特性光波导投影单元的情况得到扩展。
优选地，其一维分光光栅为柱透镜光栅或狭缝光栅，二维分光光栅为微透镜阵列。
优选地，其像素阵列-分光光栅对具有正交特性，相邻光栅单元分别允许相互具有正交特性的光通过，且各光栅单元于像素阵列上对应像素出射光的光学特 性一致于该光栅单元允许通过光的光学特性。
优选地，所述正交特性可以是线偏光、左右旋光的偏光特性，或者非同时地出现的时序特性，或者所述偏光特性和所述时序特性的结合。
优选地，各像素出射光束经光耦出器件出射光波导时，大间距地二次或更多次经光耦出器件出射，该大间距使来自同一像素的相邻两次出射光束，于观察者眼睛处的空间间距大于该眼睛瞳孔直径。
优选地，系统还包括观察者瞳孔追踪反馈器件，用于追踪观察者瞳孔位置并反馈给控制单元，对经光偶出器件大间距地二次或更多次出射光束的像素，控制单元实时加载目标场景沿入射观察者瞳孔的那束出射光束反向于投影面上的投影信息。
光栅是传统三维显示领域常用的光学器件。通过光栅分光，如一维柱透镜光栅或一维狭缝光栅，向不同视区分别投射不同视图信息；或者直接通过光栅，如二维微透镜阵列，向观察者投射不同空间矢向的光束分布，叠加形成空间光分布。
本发明将光栅引入到光波导结构，在利用光栅分光功能产生多个视图的基础上，由光栅约束各像素出射光束的出射角，通过光波导引导两个或两个以上视图出射的小发散角光束或平行窄/细光束入射观察者各眼，基于空间叠加形成观察者眼睛可以自然聚焦的空间光场分布。
本发明利用至少一个向有限远或无限远投影面投射图像的分光特性光波导投影单元堆叠构建光场显示系统。各分光特性光波导投影单元包含作为显示器件的像素阵列、分光光栅、光波导及其它组件。构成像素阵列的各基本像素集，其像素出射光经分光光栅，出射角受限地沿各自特定矢向传播，并以小发散角光束或平行窄/细光束的形态被光波导及相关组件导向观察者眼睛。来自至少一个分光特性光波导投影单元不同基本像素集的不同视图信息入射观察者瞳孔，不同矢向光束空间叠加形成该观察者眼睛可自然聚焦的三维空间光场。
本发明的具有的以下技术效果：本发明的一种基于光栅的光波导光场显示系统，借助光栅实现单目多视图，克服传统光波导显示固有的聚焦-会聚冲突问题；并基于光波导，设计实现轻薄结构的显示引擎，使之可以应用于各种屏幕及便携式显示终端，比如头戴式VR、AR、手机、iPad等。
本发明实施例的细节在附图或以下描述中进行体现。本发明的其它特性、目的和优点通过下述描述、附图而变得更为明显。
附图说明
附图用于帮助更好地理解本发明，也是本说明书的一部分。这些对实施例进行图解的附图和描述一起用以阐述本发明的原理。
图1是分光特性光波导投影单元光学结构的示意图。
图2是分光特性光波导投影单元单目多视图实现范例一的示意图。
图3是分光特性光波导投影单元单目多视图实现范例二的示意图。
图4是分光特性光波导投影单元单目多视图实现范例三的示意图。
图5是分光特性光波导投影单元单目多视图实现范例四的示意图。
图6是观察者瞳孔无法完整覆盖来自一个基本视图所有光束分布区域的示意图。
图7是堆叠分光特性光波导投影单元实现单目多合成视图范例一的示意图。
图8是堆叠分光特性光波导投影单元实现单目多合成视图范例二的示意图。
图9是来自同一像素光束不同反射次数导致的视点非确定化的示意图。
图10是基本像素集g各像素虚像等效出射光束分布的示意图。
图11是基本像素集j各像素虚像等效出射光束分布是示意图。
图12是来自同一像素光束大间距二次出射的示意图。
图13是小视区分光特性光波导投影单元投射像素阵列虚像拼连的示意图。
图14是正交特性像素阵列-分光光栅对的结构示意图。
具体实施方式
本发明所述基于光栅的光波导光场显示系统，以分光特性光波导投影单元堆栈结构作为光信息投影结构，通过引导各光波导投影单元耦出的不同视图信息至观察者瞳孔，来自不同视图的小发散角光束或平行窄/细光束空间叠加形成观察者眼睛可自然聚焦的空间光场呈现。相较于现有光栅显示光机和光波导显示光机，本发明通过膜状光波导实现轻薄结构，借助光栅投射多个视图，通过二者的结合，以轻薄的光学结构，实现克服聚焦-会聚冲突的光场显示。
图1所示为包含光栅的分光特性光波导投影单元。其主要包括像素阵列1011、分光光栅1012、中继器件1013、光耦入器件1014、光波导1015、光耦出器件1016、像面投射器件1017、补偿单元1018、和控制单元20。其中，像素阵列1011由可以加载光信息的像素排列构成，可以是OLED微显示器、LED微显示器、LCOS微显示器，或反射外部投射信息的反射面，同步地加载光信息并出射光束， 且其出射光经分光光栅1012进行分光，以受限出射角向不同矢向传播。该像素阵列1011和分光光栅1012组成一个像素阵列-分光光栅对。光波导1015为二维光波导，比如平面光波导或曲面光波导，由基体、反射面1015a和反射面1015b组成，全反射传输入射光束。光耦入器件1014将入射光耦入光波导1015，其可以是通过微加工工艺刻蚀于光波导的微结构光栅，或曝光于光波导的全息光栅，或镀膜于光波导的反射镜，或附着于光波导的衍射光栅。中继器件1013置于像素阵列-分光光栅对和光耦入器件1014之间，可以是准直透镜，准直像素阵列1011各像素出射光束，并将准直后光束牵引入光耦入器件1014，也可以是反射式成像器件，成像像素阵列1011并引导其光束入射光耦入器件1014，或者是起转向作用的反射镜，将像素阵列1011出射光反射引入光耦入器件1014，或者是上述各种器件的组合。光耦出器件1016为刻蚀于光波导的浮雕型光学元件，或者通过微加工工艺刻蚀于光波导的反射面，或者曝光于光波导的全息光栅，调制引导光波导1015全反射传播过来的光转向至耦出光出瞳1019。本发明各图中，耦出光出瞳1019用虚线来表示，以区别于反射面1015a和1015b。来自像素阵列1011不同像素的光束，被引导至入射耦出光出瞳1019，然后经像面投射器件1017，向+z向成像素虚像于投影面30，形成像素阵列1011在投影面30上的像素阵列虚像1011′。像面投射器件1017可以是透镜，或者是衍射光栅等光学器件。一种常见情况是，来自像素阵列1011不同像素的准直光束，保持准直光状态，以各自对应角度向-z向导入入射耦出光出瞳1019，然后经像面投射器件1017，向+z向会聚于投影面30上各自对应像素虚像，形成像素阵列1101在投影面30上的像素阵列虚像1011′。根据物像关系，从耦出光出瞳出射的光束，相当于从像素阵列虚像1011′各像素虚像等效出射光束。受分光光栅1012约束，像素阵列1011上各像素出射光以小出射角出射分光光栅1012，然后经其它各组成器件牵引，最后以各像素虚像出射的小出射角等效出射光传到观察者瞳孔所在区域。如图1所示，来自像素虚像p′ t和p′ t+1的光束bt和b t+1的具有小出射角。其中p′ t和p′ t+1的是像素p t和p t+1的像素虚像。该小出射角的量化值要求在于，当各像素虚像等效出射的小出射角光束到达观察者眼睛时，其覆盖区域不能大于该眼睛瞳孔尺寸。像面投射器件1017也可以被从图1中移除，此时，光束b t和b t+1为沿x向小尺寸分布的平行窄光束，对应的投影面30置于+z向无穷远处。该窄光束的 尺寸量化值要求在于，当各像素虚像等效出射的窄光束到达观察者眼睛时，其覆盖区域不能大于该眼睛瞳孔尺寸。下文中，相关小出射角或窄/细光束均遵循该量化限制。像素阵列1011不同像素出射光，还可以在去除像面投射器件1017的情况下，向+z向无限远处投射各自对应的像素虚像，或者经分光光栅1012和中继器件1013后为非平行光，然后经光波导1015和其它器件引导，虚拟会聚于+z向有限远投影面30上各自对应像素虚像。补偿单元1018，沿-z向置于光耦出器件后，用于反向消除光波导投影单元其它器件对外部环境入射光的影响，用以实现显示场景和外部真实场景之间的叠加融合，常为增强现实AR所需要。该补偿单元可以为相位膜，或实体透镜，或微结构光栅，该补偿单元附着光波导，或者刻蚀于光波导，或者曝光于光波导。在图1所示光学结构中，该补偿单元1018也可以根据需要被移除，比如当像面投射器件1017被移除，且其它器件对外部环境入射光无额外影响时。在无需外部真实场景的应用中，比如作为VR系统时，补偿单元1018可以用一个额外的遮光器件，比如挡光膜，代替。该常识性操作，图1中未示出，下文也不再累述。图1中，中继器件1013具体化为准直透镜，将像素阵列1011各像素出射光转换为不同传播方向的平行光束。
图1中，光耦入器件1014具体化为曝光于光波导1015的全息光栅，将经中继器件1013输入的不同传播方向的光束，耦入光波导1015，使耦入后各光束在光波导1015内通过全反射向光耦出器件1016传播。耦出光器件1016具体化为曝光于膜片的全息光栅，向-z向的耦出光出瞳1019偏转入射光传播方向。图1中，-z向和x向示意为垂直关系。实际上，二者也可以是非垂直关系，这时，沿x向传输过来的光束经光耦出器件1016调制沿非垂直于x的-z向传输。该情况易于理解，下述实施例示图中-z向和x向均示意为垂直关系，不再累述该非垂直情况。图1中像面投射器件1017具体化为一个凹透镜，将像素阵列1101各像素传输过来平行光束，向+z向会聚于投影面30上的对应像素虚像。补偿单元1018具体化成一个浮雕光栅器件。
图2示出了像素阵列1011出射光经分光光栅1012，分光形成的不同会聚点。具体地，以3个会聚点VR11、VR12和VR13为例，像素p1、p4、…的出射光会聚于会聚点VR11后继续传播向中继器件1013，像素p2、p5、…的出射光会聚于会聚点VR12后继续传播向中继器件1013，像素p3、p6、…的出射光会聚 于会聚点VR13后继续传播向中继器件1013。此处，各会聚点所对应像素，分别组成一个基本像素集。然后经中继器件1013、耦入器件1014、光波导1015、耦出器件1016和像面投射器件1017，基本像素集{p1、p4、…}的出射光再次会聚于视点V11，基本像素集{p2、p5、…}的出射光再次会聚于视点V12，基本像素集{p3、p6、…}的出射光再次会聚于视点V13。也可以描述为基本像素集的像素p1、p4、…的像素虚像p′1、p′4、…等效出射光会聚于视点V11；基本像素集的像素p2、p5、…的像素虚像p′2、p′5、…等效出射光会聚于视点V12；基本像素集像素p3、p6、…的像素虚像p′3、p′6、…等效出射光会聚于视点V13。一个基本像素集的像素虚像组成对应基本像素集虚像。一个基本像素集加载信息，即对应基本像素集虚像所显示信息，命名为该基本像素集对应基本像素集虚像加载的基本视图，其对应视点分别为V11、V12和V13。M s1和M s1是像素阵列虚像1011′在投影面30上分布区域的边点。由于对应像素的不同，不同基本像素集虚像在投影面30上的分布区域存在偏移，其偏移量与像素虚像间距同一量级。下文忽略该偏移，不再区分各基本像素集虚像分布区域和其对应像素阵列虚像分布区域之间的区别。当视点间距da、观察者瞳孔直径Dp、瞳孔40和投影面距离L、瞳孔40和视点所在面距离v、基本像素集虚像宽度w满足
a1+c1≤Dp(1)
时，相邻两个或更多个视点对应基本像素集出射光可以落入观察者同一个眼睛。各基本像素集，加载各自对应基本视图，基于这些视图出射光束的空间叠加，形成眼睛可以自然聚焦的空间光分布，实现光场显示。此处，a1＝(L×da)/(L+v)，c1＝|v×w|/(L+v)，||为取绝对值符号。各基本像素集对应的基本视图，由控制单元20控制加载，其任一个像素对应视图信息为目标场景沿该像素对应像素虚像等效出射光传播矢向的反向在该像素虚像上的投影信息。以图1中像素p t为例，其加载信息为场景沿光束b t反向于像素虚像p′ t上的投影信息。在视点存在情况下，各基本像素集加载的基本视图即为目标场景关于其对应视点在其对应基本像素集虚像上的视图。
图2中，沿-z向，观察者瞳孔40位于视点所在面后面，此时v取正值。图3所示为另一种情况，沿-z向，观察者瞳孔40位于视点所在面前面，此时v取负值。
图2和图3所示光学结构也可移除像面投射器件1017，存在一种情况：各像素经耦出光出瞳1019出射光为平行光束。在满足式(1)的条件下，如图4和图5，同样可以向合适位置的观察者瞳孔40投射两个或更多视图。各像素对应视图信息，由控制单元20控制加载，其中任一像素对应视图信息为目标场景沿该像素投射向观察者眼睛的平行光束反方向向无穷远所投射信息。此时，c1＝2|v|tan(FOV/2)为一个基本像素集虚像对其对应视点的张角FOV在观察者瞳孔40上覆盖区域，a1＝da。为了图示的简洁清楚，相对于图1、图2和图3，图4和图5中省略了一些组件的示出。基于图1至图3的说明，该省略易于理解，且在以下部分所绘各图中，也会出于同样理由不再示出一些组件，不再累述。
图2至图5描述了一种结合了常见光波导投影结构和分光光栅1012的分光特性光波导投影单元。实际上，具有如下功能的各种光波导及附件组成的光波导投影结构，均可结合分光光栅1012作为本申请文件中的分光特性光波导投影单元：经分光光栅1012，像素阵列1011受控出射光被耦入光波导1015并被该光波导1015传输后，借助其它光学器件向+z向投射像素阵列虚像1011′到投影面30，并向-z向经耦出光出瞳传输该像素阵列虚像1011′等效出射光。图2至图5中，入射光波导1015的光束为平行光束，然后经像面投射器件1017形成各像素虚像。当去除像面投射器件1017时，各像素虚像等效于被投影到无穷远处。实际上，入射光波导1015的光束也可以为非平行光束，只要经分光光栅1012调控的各像素出射光，经光波导1015及其它组件引导至观察者瞳孔40处时，其尺寸不大于观察者瞳孔40直径，且来自两个或大于两个视图的光束可以入射被该观察者瞳孔40。这种情况下，像面投射器件1017可以用来调整投影面30的位置到某个有限远面或无限远面，也可以去除该像面投射器件。且在上述系统中，在系统器件本身对外部环境入射光不产生影响，或者无需外部环境光信息时，补偿单元1018可以从系统移除。
一个以上的分光特性光波导投影单元可以叠加构建分光特性光波导投影单元堆栈结构作为基于光栅的光波导光场显示系统，以向更多视点投射对应基本视图。更多的视点，可以用来增加视点密度，或/和增大视点分布区域，使更多视图入射观察者瞳孔，或/和为观察者瞳孔提供更大的观察区域，即扩瞳。在该视区可以覆盖观察者双目时，该多个分光特性光波导投影单元堆栈形成的基于光栅的光波导光场显示系统可以实现双目光场呈现。当所述基于光栅的光波导光场显 示系统所产生成视点不能覆盖观察者双目时，观察者双目各需要一个该基于光栅的光波导光场显示系统作为目镜。
当观察者瞳孔40和视点分布面距离变大时，或/和当视点间距da变大时，公式(1)不再成立。在这种情况下，观察者瞳孔40将无法完整收集多于一个基本视图出射光束。如图6。采用M′＝M+1(M≧1)个分光特性光波导投影单元，堆栈构建基于光栅的分光特性光波导投影系统，可以通过提高视点数量或/和视点密度，在即使公式(1)不成立的条件下，实现单目多视图光场显示。图7以M′＝2为例进行说明。M′＝2个堆叠的分光特性光波导投影单元，来自它们像素阵列1011和1021的、相互独立的J×K＝2×3＝6个基本像素集，它们加载的基本视图分别以V1、V2、V3、V4、V5和V6为视点。其中J(J≧2)为视点分组数，K(K≧2)为各视点组中的视点个数。图7中，视点V1、V3和V5为一组，视点V2、V4和V6为J＝2个视点组中的另外一组。来自不同分光特性光波导投影单元的基本视图对应视点可以相间排列，也可以是各自毗邻排列。各基本像素集加载的对应基本视图，为目标场景关于其对应视点在其基本像素集虚像上的投影视图。图中M s1、M s2是像素阵列1011或1021的像素阵列虚像1011′或1021′在投影面30上的分布范围边点，M e1、M e2是观察者瞳孔40的边点。S1为V1和M e2连线与投影面30的交点，S2为V3和M e1连线与投影面30的交点，S3为V3和M e2连线与投影面30的交点，S4为V5和M e1连线与投影面30的交点。V1、V3和V5对应的K′＝3个基本像素集，其各一部分像素，如来自V1对应基本像素集虚像于M s1S1范围内像素虚像对应的像素、来自V3对应基本像素集虚像处于S2S3范围内像素虚像对应的像素、来自V5对应基本像素集虚像处于S4M s2范围内像素虚像对应的像素，组成一个合成像素集，该合成像素集各像素虚像组成对应合成像素集虚像，其上等效加载信息命名为合成视图。为了实现至少两个视图入射观察者瞳孔40，也要求V2、V4和V6对应的基本像素集同理组合，组成另外一个合成像素集，对应地投射另外一个合成视图给观察者瞳孔40。实现上述要求，需要至少存在两个满足以下两个条件的合成像素集：
1.其相关K′个基本像素集所对应K′个视点对观察者瞳孔40的张角拼连，在投影面30上，无缝地覆盖基本像素集虚像区域；
2.其相关K′个视点中，相邻视点对观察者瞳孔40的张角，在投影面30上所覆盖区域无缝连接。
该两个条件，要求：
((K′-1)×J×da+Dp)(L+v)/v-((K′-1)×J×da)≧w   (2)
da≤(L+v)Dp/L/J       (3)。
其中，v的正负确定，一致于图2至图5关于其正负的规定。
图7中，K′＝K，J×K＝6个基本像素集只能组合成两个合成像素集，在单目多视图前提下，仅提供两个合成视图的能力限制了观察者瞳孔40的可移动区域，即导致较小的观察区域。设计更大的M′、J、K值，可以为观察者瞳孔40提供更大的观察区域，甚至容纳多个观察者眼睛的观察区域。如图8所示，对所示观察者瞳孔40，视点v2和v4对应基本像素集可组合出一个满足上述要求的合成像素集，视点v3和v5对应基本像素集组合出另一个满足上述要求的合成像素集。随观察者瞳孔40沿x向的移动，两个满足上述条件的合成像素集，逐渐过渡为分别由v1和v3对应基本像素集组合构建，和由v2和v4对应基本像素集组合构建。则，相对于图7所示情况，观察区域发生了扩展，也即实现了扩瞳。相较于图7，为了图示的简洁清楚，图8中省略了一些组件，包括像素阵列1011和1021。
上述范例中，视点是默认等间距分布的。若视点非等间距分布时，根据上述单目多视图的要求，具体到各个视点间距，以对应具体的视点间距值代替式(1)或式(2)和式(3)的da，同理进行上述操作即可。
上述范例中，堆叠的各分光特性光波导投影单元，在采用像面投射器件1017和/或补偿单元1018的情况下，各分光特性光波导投影单元可以共用像面投射器件1017和/或补偿单元1018。
图7和图8，以投射于有限远的投影面30为例进行说明，其也同样适用于投影面30被投射于无穷远的情况。该情况下，要求各合成像素集虚像对观察者瞳孔40的覆盖角区域，一致于基本像素集虚像对观察者瞳孔40的张角。
前述范例中，对各基本像素集，其在投影面30上对应的基本像素集虚像，都存在一个对应视点。也即是说存在一组相互对应的基本像素集、基本像素集虚像和视点。实际上，组成一个基本像素集虚像的各像素虚像，也存在无共同视点的情况。如图9所示，像素阵列1011上同一基本像素集中两个像素出射光束1和2，经分光光栅1012后，过共同的会聚点VRu，然后经中继器件1013、耦入器件1014，进入光波导1015，基于全反射进行传输。如果光束1和光束2经过相同的反射次数出射，则它们将会在VRu的像点Vu，重新会聚。但由于光束1 和光束2在光波导1015界面反射角的不同，它们到达耦出光器件1016时，反射次数出现不同，则经耦出光出瞳1019，光束1和光束2不再会聚于点Vu。此时，该基本像素集对应各像素虚像，不再有共同的视点。又例如，采用相同周期结构的光栅耦出器件1014，其对不同角度入射光束的偏转角度由光栅方程确定，会导致同一基本像素集虚像各像素虚像间距不相等，它们等效出射光也不会聚于一个视点。再例如，以二维微透镜阵列作为分光光栅1012时，对应像素阵列-分光光栅对构成一个基本的集成成像结构，各微透镜分别对应包含N个像素的像素组，各像素组中相对排列位置相同的像素分别成组，构成像素阵列1011的N个基本像素集，其中N≧2。此时，一个基本像素集各像素出射光，经分光光栅1012，存在无公同会聚点情况，此时像素虚像可没有共同的视点。其中，所述二维光栅情况下，部分光栅单元对应像素受像素阵列排列区域形状限制发生缺失而不足M时，缺失的像素以不发光的虚拟像素代替，以使各基本像素集具有相同数量的像素。对于诸如此类基本像素集各像素虚像不存在共同视点的情况，基于光线追踪，设计两个或两个以上基本像素集出射光线全部入射观察者同一瞳孔，同样可以实现单目多视图的光场显示。其各像素加载信息，为沿该像素对应像素虚像等效出射光反向，待显示场景在该像素虚像上的投射信息。其基本像素集所加载信息，同样命名为一个基本视图，此类基本视图对应的各像素虚像无公共视点。当至少两个此类基本像素集出射光束无法完全入射观察者同一瞳孔时，需要设计生成合成像素集。该合成像素集由两个或多个此类基本像素集各一个区域的像素组合而成，其各像素的像素虚像，可以入射观察者同一瞳孔40。如图10所示，基本像素集g，其各像素虚像等效出射光于观察者瞳孔40处，由于分布过于分散而不能完全入射该观察者瞳孔40。为了图示的清晰，基本像素集g的像素虚像仅以少量个数表示。图11所示基本像素集j，其各像素虚像等效出射光于观察者瞳孔40处，由于分布过于分散而不能完全入射该观察者瞳孔40。但二者各一个部分像素可组成一个其像素虚像分布区域一致于基本像素集虚像分布区域的合成像素集，该合成像素集各像素出射光，可以全部入射观察者瞳孔40。一个合成像素集组成像素所加载信息，命名为该合成像素集加载的合成视图。为了实现单目多视图，需要存在另外至少一个同样性质的合成像素集。一个合成像素集相关的各基本像素集，可以来自同一个分光特性光波导投影单元，也可以来自堆叠的不同分光特性光波导投影单元。更多分光特性光波导投影单元堆叠，可以提供更多 的合成像素集，为观察者瞳孔40提供更多的同时可接收合成视图，或/并为观察者提供更大的观察区域，即扩瞳，甚至同时允许两个或更多个眼睛的单目多视图呈现。
图10和图11是以投影面30处于有限远为例进行的说明。相关过程也适用于投影面30被投射于无穷远的情况，该情况下，要求合成像素集虚像对观察者瞳孔40的张角，一致于基本像素集虚像对观察者瞳孔40的张角。
上述各范例中，各像素出射光束也可以通过耦出器件1016，二次或更多次出射耦出光出瞳1019，但来自同一像素光相邻次两次出射耦出光出瞳1019的光束，在观察者瞳孔40所处区域内的空间间距，如图12的S t和S t+1，要大于观察者瞳孔40尺寸Dp，防止来自同一像素的光光信息沿两个或更多个矢向同时入射观察者瞳孔40。为了实现这一个功能，根据设计需要，耦出光出瞳1019可以设计为非连续的多个子耦出光出瞳的组合，使完成一次全反射情况下沿光波导传输距离小于Dp的光束经过多次的全反射后再二次或更多次出射。当各像素出射光束发生上述二次或更多次经耦出光出瞳1019出射时，系统需要观察者瞳孔追踪反馈器件50，如图12，追踪反馈观察者瞳孔位置，由控制单元20向该像素加载信息，该信息为目标场景沿该像素经耦出光出瞳1019出射光束中入射观察者瞳孔那束光的反向，在投影面上的投影信息。
上述实例中，所述分光特性光波导投影单元可以由两个或更多个单色分光特性光波导投影单元堆栈而成，该两个或更多个单色分光特性光波导投影单元投射光信息波长不同，所投射不同波长的像素阵列虚像混光合成为彩色虚像。所述分光特性光波导投影单元也可以为由两个或更多个小视角分光特性光波导投影单元堆栈而成，各小视角分光特性光波导投影单元像素阵列虚像拼连扩展，如图13中来自不同小视角分光特性光波导投影单元的像素阵列虚像1011a′和1011b′，拼连为一个扩展的像素阵列虚像1011′，对应视角得到扩展。其中区域1011a′上的像素虚像为小视角分光特性光波导投影单元1011a的像素虚像，区域1011b′上的像素虚像为小视角分光特性光波导投影单元1011b的像素虚像。为了图示清晰，补偿单元1018未示出。
上述实例中，所述分光特性光波导投影单元中可置光阑60，如图2所示，挡除像素阵列1011各像素经非对应光栅单元出射带来的噪声。另外一种抑制光栅分光固有噪声的方法是设计正交特性像素阵列-分光光栅对，即，相邻光栅单 元通过附着的正交检测单元，分别仅允许相互具有正交特性的光通过，各正交检测单元组成正交检测器件80，如图14中的正交检测单元80a，80b，80c，…组成正交检测器件80。各光栅单元于像素阵列1011上对应的像素，其出射光的光学特性由正交生成单元控制，使之一致于该光栅单元允许通过光的光学特性。各正交生成单元组成正交生成器件90，如图14中的正交生成单元90a，90b，90c，…组成正交检测器件90。常用的正交特性可以是线偏光、左右旋光的偏光特性，此时可以通过偏光片于各光栅单元作为正交检测单元来实现。对应的正交生成单元也可为偏光片，或通过像素阵列1011的生产工艺，使其像素出射光直接具有相应光学特性。另外，时间复用也是一种常用的正交特性，此时需要通过置于各光栅单元上的开关时序可控孔径做为正交检测单元，对应正交生成单元，可以是开关时序可控孔径，也可以直接利用控制单元20控制对应像素的工作和不工作来实现。
本发明的核心思想是通过一个或多个分光特性光波导投影单元，利用其分光光栅对像素阵列各像素出射光的分光控制及出射角约束，通过光波导向观察者瞳孔投射两个或两个以上的视图，其对应光束空间叠加形成可自然聚焦空间光场分布。各像素出射光，经光栅分光和光波导传播，以小发散角光束或窄/细平行光束入射观察者瞳孔，入射观察者瞳孔时，光束入射面尺寸不大于瞳孔直径。其它各种光波导投影结构，比如设计了其它各种光耦入器件和其它各种中继器件的光波导投影单元，或设计了耦入时分割图像并在耦出是进行图像复原的光组件的光波导投影单元，结合分光光栅，均可以作为分光特性光波导投影单元，进行基于光栅的光波导光场显示。且本发明所述系统还可以进一步延申，比如通过设计具有不同调焦能力的像面投射器件1017，可以在不同深度上形成多个投影面，然后在每个深度的投影面上，再基于本发明所述原理在该深度附近一定范围内场景的呈现，以提高显示场景的景深。或者设计时序可调焦的像面投射器1017，时序在不同深度上形成多个投影面，每个深度的投影面上，同步基于本发明所述过程进行该深度附近一定范围内场景的呈现，基于视觉滞留效应提高显示场景的景深。也可以通过追踪观察者双目实时会聚深度，然后控制仅于该深度所处投影面或该深度附近投影面上，基于本发明所述过程进行该深度附近一定范围内场景的呈现。该时序可调焦的像面投射器1017，比如是焦距时序可控的液晶透镜，或者多片液晶叠加而成的液晶片组，其中不同的液晶片组合具有不同的调焦能力， 通过时序驱动不同的液晶片组合实现两个或更多个投影面。
以上仅为本发明的优选实施例，但本发明的设计构思并不局限于此，凡利用此构思对本发明做出的非实质性修改，也均落入本发明的保护范围之内。比如，所采用的分光光栅，并不局限于前文所述一维柱透镜光栅、一维狭缝光栅和二维微透镜阵列光栅。相应地，所有相关实施例都落入本发明的保护范围内。

Claims (15)

  1. 基于光栅的光波导光场显示系统，其特征在于，包括：
    分光特性光波导投影单元堆栈结构，由M个分光特性光波导投影单元堆叠构成，各分光特性光波导投影单元向+z向投射虚像，并通过其耦出光出瞳向-z向传播该投射虚像所呈现光信息,其中M≧1；
    其中，分光特性光波导投影单元包括：像素阵列，该像素阵列用于加载光信息并出射光束；分光光栅，该分光光栅由光栅单元组成，沿所述像素阵列出射光束传输方向置于像素阵列前，调控像素阵列各像素经对应光栅单元后出射光束的传输方向，并约束其出射角，该分光光栅和所述像素阵列组成像素阵列-分光光栅对；光波导，该光波导由基体和全反射面组成，通过全反射传输入射光束；光耦入器件，将入射光耦入光波导；中继器件，该中继器件置于分光光栅和光耦入器件之间，引导像素阵列各像素经对应光栅单元出射光束入射光耦入器件；光耦出器件，引导光波导全反射传播过来的来自像素阵列各像素的光束转向至耦出光出瞳，并出射光波导，其中经耦出光出瞳出射的来自于各像素的光束，沿其出射方向反向的虚会聚点，定义为该像素对应的像素虚像，该出射光束为该像素虚像的等效出射光，各像素对应像素虚像于投影面上构建像素阵列虚像；
    控制单元，在各时间点，控制所述像素阵列各像素加载各自对应信息，其中任一像素对应信息为目标场景沿该像素对应像素虚像等效出射光束传播矢向的反向在该像素虚像上的投影信息；
    所述基于光栅的光波导光场显示系统被设置为能够向观察者瞳孔投射来自至少两个或两个以上基本像素集的、或/和合成像素集的视图信息，且出射角受分光光栅约束的各像素出射光束，入射观察者瞳孔时其空间尺寸小于该瞳孔尺寸；
    其中，所述基本像素集定义如下：当采用一维光栅的分光特性光波导投影单元时，其像素阵列各像素出射光基于光栅分光将被分别引导至N个视区的N组像素，作为N个基本像素集，当采用二维光栅的分光特性光波导投影单元时，光栅单元分别对应包含N个像素的像素组中，相对排列位置相同的像素分别成组，作为N个基本像素集，其中N≧2；
    并且其中，所述合成像素集定义如下：由不同基本像素集各一个区域内像素拼合而成，该合成像素集各像素的像素虚像遍布像素阵列虚像分布区域。
  2. 根据权利要求1所述基于光栅的光波导光场显示系统，其特征在于，所述 分光特性光波导投影单元还包括像面投射器，或/和补偿单元，
    其中所述像面投射器件沿光束传输方向置于耦出光出瞳前，将光耦出器件引导来的、来自于像素阵列不同像素的光束，反向会聚于新的投影面上各自对应的新的像素虚像，构建像素阵列在投影面上的新的像素阵列虚像，所述经耦出光出瞳出射光束为该新的像素阵列虚像上各新的像素虚像等效出射光束，其中新的投影面、新的像素虚像、新的像素阵列虚像代替未引入像面投射器时的投影面、像素虚像、像素阵列虚像，作为引入像面投射器时的实际采用投影面、像素虚像、像素阵列虚像；所述补偿单元沿-z向置于光耦出器件后，用于消除分光特性光波导投影单元中的其它器件对外部环境入射光的影响。
  3. 根据权利要求1或2所述基于光栅的光波导光场显示系统，其特征在于，所述分光特性光波导投影单元经光波导耦出光出瞳出射各光束为平行光，其像素阵列虚像位置对应+z向无穷远处。
  4. 根据权利要求1或2所述基于光栅的光波导光场显示系统，其特征在于，所述分光特性光波导投影单元中，二维光栅的部分光栅单元对应像素受像素阵列排列区域形状限制发生缺失而不足M时，缺失的像素以不发光的虚拟像素代替。
  5. 根据权利要求1或2所述基于光栅的光波导光场显示系统，其特征在于，所述分光特性光波导投影单元中置有光阑，用于挡除像素阵列各像素经非对应光栅单元出射光。
  6. 根据权利要求2所述基于光栅的光波导光场显示系统，其特征在于，堆叠的各分光特性光波导投影单元，共用像面投射器件或/和补偿单元。
  7. 根据权利要求1或2所述基于光栅的光波导光场显示系统，其特征在于，所述像素阵列为OLED微显示器、LED微显示器、LCOS微显示器，或反射外部投射信息的反射面，所述光波导为平面或曲面光波导，所述光耦入器件是通过微加工工艺刻蚀于光波导的微结构光栅，或曝光于光波导内的全息光栅，或镀膜于光波导的反射镜，或附着于光波导表面的衍射光栅，所述中继器件为准直透镜，或/和成像透镜，或/和光束偏转器，所述光耦出器件为刻蚀于光波导的微结构光栅，或者加工于光波导的反射面，或者曝光于光波导的全息光栅。
  8. 根据权利要求2所述基于光栅的光波导光场显示系统，其特征在于，所述像面投射器件为单透镜或组合透镜，或曝光于光波导的全息光栅，或刻蚀于光 波导的微结构光栅，所述补偿单元为相位膜，或微结构光栅，该补偿单元附着光波导，或者刻蚀于光波导，或者曝光于光波导。
  9. 根据权利要求1或2所述基于光栅的光波导光场显示系统，其特征在于，所述分光特性光波导投影单元由两个或更多个单色分光特性光波导投影单元堆栈而成，该两个或更多个单色分光特性光波导投影单元投射光信息波长不同，所投射不同波长的虚像混光合成为彩色虚像。
  10. 根据权利要求1或2所述基于光栅的光波导光场显示系统，其特征在于，所述分光特性光波导投影单元为由两个或更多个小视角分光特性光波导投影单元堆栈而成，各小视角分光特性光波导投影单元所投射像素阵列虚像覆盖视角拼合，扩展分光特性光波导投影单元投射信息所覆盖视角，
    其中所述小视角分光特性光波导投影单元具有和所述分光特性光波导投影单元相同的光学结构，且该两个或多个小视角分光特性光波导投影单元所投射像素阵列虚像的覆盖视区错位分布，通过该错位视区分布的拼合，使该两个或多个小视角分光特性光波导投影单元堆栈而成分光特性光波导投影单元投射信息所覆盖视区相对于一个小视角分光特性光波导投影单元的情况得到扩展。
  11. 根据权利要求1或2所述基于光栅的光波导光场显示系统，其特征在于，其一维分光光栅为柱透镜光栅或狭缝光栅，二维分光光栅为微透镜阵列。
  12. 根据权利要求1或2所述基于光栅的光波导光场显示系统，其特征在于，其像素阵列-分光光栅对具有正交特性，相邻光栅单元分别允许相互具有正交特性的光通过，且各光栅单元于像素阵列上对应像素出射光的光学特性一致于该光栅单元允许通过光的光学特性。
  13. 根据权利要求12所述基于光栅的光波导光场显示系统，其特征在于，所述正交特性可以是线偏光、左右旋光的偏光特性，或者非同时地出现的时序特性，或者所述偏光特性和所述时序特性的结合。
  14. 根据权利要求1或2所述基于光栅的光波导光场显示系统，其特征在于，各像素出射光束经光耦出器件出射光波导时，大间距地二次或更多次经光耦出器件出射，该大间距使来自同一像素的相邻两次出射光束，于观察者眼睛处的空间间距大于该眼睛瞳孔直径。
  15. 根据权利要求14所述基于光栅的光波导光场显示系统，其特征在于，系统还包括观察者瞳孔追踪反馈器件，用于追踪观察者瞳孔位置并反馈给控制单元， 对经光偶出器件大间距地二次或更多次出射光束的像素，控制单元实时加载目标场景沿入射观察者瞳孔的那束出射光束反向于投影面上的投影信息。
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