CN114089470A

CN114089470A - Holographic optical waveguide, manufacturing device thereof and near-to-eye display device

Info

Publication number: CN114089470A
Application number: CN202210066997.5A
Authority: CN
Inventors: 唐笑运; 宋强; 郭晓明; 马国斌
Original assignee: Long Optoelectronics Co ltd
Current assignee: Long Optoelectronics Co ltd
Priority date: 2022-01-20
Filing date: 2022-01-20
Publication date: 2022-02-25
Anticipated expiration: 2042-01-20
Also published as: CN114089470B

Abstract

The embodiment of the invention provides a holographic optical waveguide, a manufacturing device thereof and near-to-eye display equipment, wherein the manufacturing device of the holographic optical waveguide comprises a light source, a first light splitting unit, a second light splitting unit, a first reflecting unit, a second reflecting unit, a third reflecting unit, a special-shaped prism and a holographic dry plate; the holographic dry plate is exposed through the light source, the light splitting units, the reflecting units and the special-shaped prism, and the holographic optical waveguide can be manufactured. The manufacturing device enables the holographic dry plate to be exposed to form a grating structure, so that the holographic optical waveguide is manufactured, the manufacturing efficiency is high, the cost is low, the yield is high, the manufactured holographic optical waveguide has the wavelength multiplexing and/or angle multiplexing functions, the light diffraction efficiency can be improved when the manufactured holographic optical waveguide is applied to near-to-eye display equipment, the field angle and the eye movement range can be remarkably improved, and the size of an optical machine can be reduced.

Description

Holographic optical waveguide, manufacturing device thereof and near-to-eye display device

Technical Field

The embodiment of the invention relates to the technical field of optics, in particular to a holographic optical waveguide, a manufacturing device thereof and near-to-eye display equipment.

Background

Augmented reality is a technology for fusing virtual information and a real world, wherein a near-eye display device is a key link in the augmented reality technology. The near-eye display device enables a user to see a real world and a virtual image constructed by a computer, a conical range formed by human eyes and the virtual image is called a field angle, the distance between the human eyes and the display device when the human eyes can see a full virtual image is called an exit pupil distance, and the range in which the human eyes can shake when the human eyes can see the full virtual image at a certain exit pupil distance is called an eye movement range. How to reduce the volume of the optical machine while significantly increasing the field angle and the eye movement range is a great challenge in augmented reality.

At present, there are two common optical waveguide schemes which can achieve a small optical machine volume and realize a large field angle and a large eye movement range. One is to adopt array optical waveguide, but the scheme adopts a glass cold processing technology, so that the process difficulty is high, the cost is high, and the yield is low; the other is to use a relief grating waveguide, but this solution requires expensive grating etching and nanoimprinting, resulting in high instrument cost.

Disclosure of Invention

The embodiment of the invention aims to provide a holographic optical waveguide, a manufacturing device thereof and near-eye display equipment, wherein the manufacturing device is simple to operate, the efficiency of manufacturing the holographic optical waveguide is high, the cost is low, the yield is high, and the manufactured holographic optical waveguide is applied to the near-eye display equipment, so that the volume of an optical machine can be reduced while the visual angle and the eye movement range are remarkably improved.

In a first aspect, one technical solution adopted in the embodiments of the present invention is: provided is a device for manufacturing a holographic optical waveguide, including: the holographic optical system comprises a light source, a first light splitting unit, a second light splitting unit, a first reflecting unit, a second reflecting unit, a third reflecting unit, a special-shaped prism and a holographic dry plate; the first reflection unit and the first light splitting unit are arranged on the light emitting side of the light source; the first incident surface of the special-shaped prism is arranged in the reflection direction of the first reflection unit; the second reflection unit is arranged on the first light-emitting side of the first light splitting unit, the third reflection unit is arranged on the second light-emitting side of the first light splitting unit, and the second light splitting unit is arranged on the third light-emitting side of the first light splitting unit; the first surface of the holographic dry plate is arranged in the reflection direction of the second reflection unit and in the reflection direction of the third reflection unit; the second incident surface of the special-shaped prism is arranged on the first light-emitting side of the second light splitting unit, and the third incident surface of the special-shaped prism is arranged on the second light-emitting side of the second light splitting unit; the second surface of the holographic dry plate is arranged close to the emergent surface of the special-shaped prism;

in some embodiments, the light of the light source comprises a first light and a first light beam that are parallel to each other; the first reflection unit is also arranged in the propagation direction of the first light beam; the first light splitting unit is also arranged in the propagation direction of the first light; the first light beam is emitted to a first incident surface of the special-shaped prism through the first reflecting unit and is emitted to a second surface of the holographic dry plate through an emitting surface of the special-shaped prism; the first light is divided into a second light beam, a third light beam and a second light beam through the first light splitting unit; the second light beam is emitted to the second reflection unit through the first light emitting side of the first light splitting unit and is emitted to the first surface of the holographic dry plate through the second reflection unit; the third light beam is emitted to the third reflection unit through the second light emitting side of the first light splitting unit and is emitted to the first surface of the holographic dry plate through the third reflection unit; the second light is emitted to the second light splitting unit through the first light emitting side of the first light splitting unit and is split into a fourth light beam, a fifth light beam and a sixth light beam through the second light splitting unit; the fourth light beam is emitted to the second incident surface of the special-shaped prism through the first light-emitting side of the second light splitting unit and is emitted to the second surface of the holographic dry plate through the emitting surface of the special-shaped prism; the fifth light beam and the sixth light beam are both emitted to a third incident surface of the special-shaped prism through a second light-emitting side of the second light splitting unit and are emitted to a second surface of the holographic dry plate through an emitting surface of the special-shaped prism; the holographic stem plate comprises a first area, a second area and a third area, and the holographic stem plate is used for forming a coupling-in grating in the first area by the first light beam and the second light beam in a coherent mode, forming a coupling-out grating in the second area by the third light beam and the fifth light beam in a coherent mode, and forming a turning grating in the third area by the fourth light beam and the sixth light beam in a coherent mode, so that a holographic optical waveguide is formed.

In some embodiments, the first beam splitting unit comprises a first beam splitter and a second beam splitter; the light source is arranged on the light source, the light source is arranged on the light inlet side of the first spectroscope, the light inlet side of the second spectroscope is arranged on the first light outlet side of the first spectroscope, the second spectroscope is arranged on the second light outlet side of the first spectroscope, the second reflecting unit is arranged on the first light outlet side of the second spectroscope, and the third reflecting unit is arranged on the second light outlet side of the second spectroscope.

In some embodiments, the second reflecting unit includes a first mirror; the first reflector is arranged on a first light-emitting side of the first light splitting unit, and the first surface of the holographic dry plate is arranged in the reflection direction of the first reflector.

In some embodiments, the third reflecting unit includes a second mirror and a third mirror; the second reflector is arranged on the second light-emitting side of the first light splitting unit, the third reflector is arranged in the reflecting direction of the second reflector, and the first surface of the holographic dry plate is arranged in the reflecting direction of the third reflector.

In some embodiments, the first reflecting unit includes a fourth mirror and a fifth mirror; the fourth reflector is arranged on the light emitting side of the light source, the fifth reflector is arranged in the reflecting direction of the fourth reflector, and the first incident surface of the special-shaped prism is arranged in the reflecting direction of the fifth reflector.

In some embodiments, the second light splitting unit includes a third beam splitter, a sixth mirror, and a seventh mirror; the income light side of third beam splitter locates the third light-emitting side of first beam splitter unit, the second incident surface of dysmorphism prism is located the first light-emitting side of third beam splitter, the sixth speculum is located the second light-emitting side of third beam splitter, the seventh speculum is located on the direction of reflection of sixth speculum, the third incident surface of dysmorphism prism is located on the direction of reflection of seventh speculum.

In some embodiments, the first mirror, the third mirror, the fifth mirror, the third beam splitter, and the seventh mirror are respectively fixed to different track rotation tables.

In some embodiments, the shaped prism further has a reflective surface; the special-shaped prism is used for receiving the fifth light beam and the sixth light beam through the third incident surface, reflecting the fifth light beam and the sixth light beam to the emergent surface through the reflecting surface, and enabling the fifth light beam and the sixth light beam to be emergent to the second surface of the holographic dry plate through the emergent surface.

In some embodiments, the light source comprises at least one laser and a beam combiner; each laser is arranged at each input end of the beam combiner, and the first reflection unit and the first light splitting unit are arranged at the output end of the beam combiner.

In some embodiments, the fabrication apparatus further comprises a polarization splitting prism; the incident end of the polarization beam splitter prism is arranged at the output end of the beam combiner, and the first reflection unit and the first beam splitter unit are arranged at the emergent end of the polarization beam splitter prism.

In some embodiments, the fabrication apparatus further comprises a spatial filter and a collimation unit; the light-in side of the spatial filter is arranged at the emergent end of the polarization beam splitter prism, the light-out side of the spatial filter is arranged at the light-in side of the collimation unit, and the first reflection unit and the first beam splitter unit are arranged at the light-out side of the collimation unit.

In a second aspect, an embodiment of the present invention further provides a holographic optical waveguide, where the holographic optical waveguide is obtained by the manufacturing apparatus in any one of the first aspect, and the holographic optical waveguide is an angle multiplexing holographic and/or wavelength multiplexing holographic optical waveguide.

In some embodiments, in the holographic optical waveguide, a fringe period Λ 1 of the incoupling grating, a fringe period Λ 1 of the outcoupling grating, and a fringe period Λ 3 of the turning grating formed by exposure to light of the same wavelength satisfy the following relationship:

Λ1=Λ2；

Λ3=Λ1/(2cos(α/2))；

wherein α is an angle between grating lines of the coupling-in grating and the coupling-out grating, α/2 is an angle between grating lines of the coupling-in grating and the turning grating, or α/2 is an angle between grating lines of the coupling-out grating and the turning grating.

In some embodiments, the diffraction efficiency of the turning grating gradually increases from a side facing the incoupling grating to a side facing away from the incoupling grating, and the diffraction efficiency of the outcoupling grating gradually increases from a side facing the turning grating to a side facing away from the turning grating.

In a third aspect, embodiments of the present invention further provide a near-eye display device, including at least one layer of the holographic optical waveguide according to any one of the second aspects.

In some embodiments, the near-eye display device includes a layer of holographic optical waveguide that is a wavelength-multiplexed and angle-multiplexed holographic optical waveguide.

In some embodiments, the near-eye display device comprises M layers of holographic optical waveguides, each of the M layers of holographic optical waveguides being a wavelength-multiplexed holographic optical waveguide, the M layers of holographic optical waveguides corresponding to M sets of different exposure angles, respectively; or the near-eye display device comprises N layers of holographic optical waveguides, wherein the N layers of holographic optical waveguides are angle multiplexing holographic optical waveguides, the N layers of holographic optical waveguides correspond to N different exposure wavelengths respectively, M is an integer greater than or equal to 2, and N is an integer greater than or equal to 2.

Compared with the prior art, the invention has the beneficial effects that: different from the situation of the prior art, an embodiment of the present invention provides a holographic optical waveguide, a manufacturing apparatus thereof, and a near-to-eye display device, where the manufacturing apparatus of the holographic optical waveguide includes a light source, a first light splitting unit, a second light splitting unit, a first reflection unit, a second reflection unit, a third reflection unit, a special-shaped prism, and a holographic dry plate; the holographic dry plate is exposed through the light source, the light splitting units, the reflecting units and the special-shaped prism, and the holographic optical waveguide can be manufactured. The manufacturing device enables the holographic dry plate to be exposed to form the grating structure, so that the holographic optical waveguide is manufactured, the operation is simple, the manufacturing efficiency is high, the cost is low, the yield is high, the manufactured holographic optical waveguide is applied to near-to-eye display equipment, the light diffraction efficiency can be improved, the visual angle and the eye movement range can be remarkably improved, and the size of an optical machine can be reduced.

Drawings

One or more embodiments are illustrated by the accompanying figures in the drawings that correspond thereto and are not to be construed as limiting the embodiments, wherein elements/modules and steps having the same reference numerals are represented by like elements/modules and steps, unless otherwise specified, and the drawings are not to scale.

FIG. 1 is a schematic structural diagram of an apparatus for fabricating a holographic optical waveguide according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a holographic optical waveguide according to an embodiment of the present invention;

FIG. 3 is a schematic view of light vectors during exposure of a holographic grating according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of holographic interference fringes of a holographic grating provided by an embodiment of the present invention;

FIG. 5 is a schematic diagram of holographic interference fringes of another holographic grating provided by an embodiment of the present invention;

FIG. 6 is a three-dimensional view of a shaped prism according to an embodiment of the present invention;

FIG. 7 is a three-dimensional view of a portion of the optical path of FIG. 1 when the shaped prism has the structure shown in FIG. 6;

FIG. 8 is a three-dimensional view of another shaped prism provided by embodiments of the present invention;

FIG. 9 is a three-dimensional view of a portion of the optical path of FIG. 1 when the shaped prism has the structure shown in FIG. 8;

FIG. 10 is a schematic diagram of an alternative holographic optical waveguide fabrication apparatus according to embodiments of the present invention;

FIG. 11 is a schematic structural diagram of a three-layer holographic optical waveguide according to an embodiment of the present invention.

Description of reference numerals: 10-light source, 11-red laser, 12-blue laser, 13-green laser, 14-beam combiner, 20-first beam splitting unit, 21-first beam splitter, 22-second beam splitter, 30-second beam splitting unit, 31-third beam splitter, 32-sixth mirror, 33-seventh mirror, 40-first reflection unit, 41-fourth mirror, 42-fifth mirror, 50-second reflection unit, 60-third reflection unit, 61-second mirror, 62-third mirror, 70-special prism, 80-holographic dry plate, 81-incoupling grating, 82-outing grating, 83-turning grating, 91-polarization beam splitter, 92-spatial filter, 93-collimation unit, 1-a first holographic optical waveguide, 2-a second holographic optical waveguide, 3-a third holographic optical waveguide, K1-a wave vector of a first light beam, K2-a wave vector of a second light beam, a K-grating vector, a D-grating period, a holographic interference fringe obtained by exposure of R-red light, a holographic interference fringe obtained by exposure of G-green light, a holographic interference fringe obtained by exposure of B-blue light, and Λ_RFringe period, Λ, of holographic interference fringes obtained by red light exposure_GFringe period of holographic interference fringes obtained by green light exposure, Λ_B-a fringe period of the holographic interference fringes obtained for blue exposure, a-grating fringe spacing period, a ζ -fringe tilt angle, ζ 1-a fringe tilt angle of the holographic interference fringes obtained for exposure corresponding to the first set of exposure angles, ζ 2-a fringe tilt angle of the holographic interference fringes obtained for exposure corresponding to the second set of exposure angles, ζ 3-a fringe tilt angle of the holographic interference fringes obtained for exposure corresponding to the third set of exposure angles, M1-a first light, M2-a second light, L1-a first light, L2-a second light, L3-a third light, L4-a fourth light, L5-a fifth light, L6-a sixth light.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

In order to facilitate an understanding of the present application, the present application is described in more detail below with reference to the accompanying drawings and specific embodiments. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It should be noted that, if not conflicted, the various features of the embodiments of the invention may be combined with each other within the scope of protection of the present application. In addition, although the functional blocks are divided in the device diagram, in some cases, the blocks may be divided differently from those in the device. Further, the terms "first," "second," and the like, as used herein, do not limit the data and the execution order, but merely distinguish the same items or similar items having substantially the same functions and actions.

In a first aspect, an embodiment of the present invention provides a device for manufacturing a holographic grating, please refer to fig. 1, the device includes: the holographic plate comprises a light source 10, a first light splitting unit 20, a second light splitting unit 30, a first reflecting unit 40, a second reflecting unit 50, a third reflecting unit 60, a special-shaped prism 70 and a holographic dry plate 80.

The first reflecting unit 40 is disposed on the light emitting side of the light source 10, and the first incident surface of the irregular prism 70 is disposed in the reflecting direction of the first reflecting unit 40. The first light splitting unit 20 is disposed on the light emitting side of the light source 10, the second reflecting unit 50 is disposed on the first light emitting side of the first light splitting unit 20, the third reflecting unit 60 is disposed on the second light emitting side of the first light splitting unit 20, the second light splitting unit 30 is disposed on the third light emitting side of the first light splitting unit 20, the first surface of the holographic dry plate 80 is disposed on the reflecting direction of the second reflecting unit 50 and on the reflecting direction of the third reflecting unit 60, the second incident surface of the special-shaped prism 70 is disposed on the first light emitting side of the second light splitting unit 30, the third incident surface of the special-shaped prism 70 is disposed on the second light emitting side of the second light splitting unit 30, and the second surface of the holographic dry plate 80 is disposed adjacent to the emitting surface of the special-shaped prism 70.

The holographic grating manufacturing device can expose a holographic dry plate to form a grating structure, so that a holographic optical waveguide is manufactured, the holographic optical waveguide can be subsequently used for manufacturing a wavelength multiplexing and/or angle multiplexing holographic optical waveguide, and can also be used for manufacturing a monochrome holographic optical waveguide and a full-color holographic optical waveguide, the manufacturing efficiency is high, the cost is low, the yield is high, the manufactured holographic optical waveguide has the wavelength multiplexing and/or angle multiplexing function, the light diffraction efficiency can be improved when the holographic optical waveguide is applied to near-eye display equipment, and the size of an optical machine can be reduced while the visual angle and the eye movement range are remarkably improved.

In some embodiments, with continued reference to fig. 1, the light emitted from the light source 10 may include a first light beam M1 and a first light beam L1 that are parallel to each other; the first reflecting unit 40 is also arranged in the propagation direction of the first light beam L1; the first light splitting unit 20 is also arranged in the propagation direction of the first light ray M1; the first light beam L1 exits to the first incident surface of the special-shaped prism 70 through the first reflection unit 40, and exits to the second surface of the holographic dry plate 80 through the exit surface of the special-shaped prism 70; the first light ray M1 is split into a second light beam L2, a third light beam L3 and a second light ray M2 by the first light splitting unit 20; the second light beam L2 exits to the second reflecting unit 50 through the first light exit side of the first light splitting unit 20, and exits to the first surface of the holographic plate 80 through the second reflecting unit 50; the third light beam L3 exits to the third reflection unit 60 through the second light exit side of the first light splitting unit 20, and exits to the first surface of the holographic plate 80 through the third reflection unit 60; the second light beam M2 exits to the second light splitting unit 30 through the first light exit side of the first light splitting unit 20, and is split into a fourth light beam L4, a fifth light beam L5 and a sixth light beam L6 through the second light splitting unit 30; the fourth light beam L4 exits to the second incident surface of the special-shaped prism 70 through the first light exit side of the second light splitting unit 30, and exits to the second surface of the holographic dry plate 80 through the exit surface of the special-shaped prism 70; the fifth light beam L5 and the sixth light beam L6 both exit to the third incident surface of the special-shaped prism 70 through the second light exit side of the second light splitting unit 30, and exit to the second surface of the holographic dry plate 80 through the exit surface of the special-shaped prism 70; the holographic dry plate 80 includes a first region, a second region, and a third region for coherently forming a coupling-in grating by the first light beam L1 and the second light beam L2 in the first region, coherently forming a coupling-out grating by the third light beam L3 and the fifth light beam L5 in the second region, and coherently forming a turning grating by the fourth light beam L4 and the sixth light beam L6 in the third region, thereby forming a holographic optical waveguide.

Specifically, the holographic plate 80 includes a waveguide substrate and a holographic material coated on the surface of the waveguide substrate, wherein the waveguide substrate may be made of transparent glass or resin, and the holographic material may be a photopolymer, silver salt, dichromated gelatin, photorefractive material, photoanisotropic material, or any other photosensitive material that can be used to record interference fringes after exposure. Illustratively, the silver salt can be silver halide (AgX, X being F, Cl, Br, or I).

Then, in the manufacturing apparatus, the beam splitting units and the reflection units are matched with the special-shaped prism 70, so that the light emitted by the light source 10 can form six beams, and finally the first beam L1 and the second beam L2 can be coherent to form holographic interference fringes in a first area of the holographic dry plate 80, the third beam L3 and the fifth beam L5 can be coherent to form holographic interference fringes in a second area of the holographic dry plate 80, and the fourth beam L4 and the sixth beam L6 can be coherent to form holographic interference fringes in a third area of the holographic dry plate 80; thus, the hologram interference fringes expose three regions of the hologram dry plate 80, respectively, and are recorded by the hologram dry plate 80, as shown in fig. 2, and finally, an incoupling grating may be formed in the first region, an outcoupling grating may be formed in the second region, and a turning grating may be formed in the third region. It can be seen that after exposure, the holographic plate 80 can be transformed into a holographic optical waveguide having an incoupling grating, an outcoupling grating and a turning grating, wherein the incoupling grating is used for incoupling image light with image information into the waveguide substrate and making the image light totally reflected and propagated toward the turning grating, then the turning grating is used for receiving and diffracting the image light incoupled by the incoupling grating, a part of the image light is turned to be totally reflected and propagated toward the outcoupling grating, a part of the image light is continuously propagated toward the original direction, and the outcoupling grating is used for outcoupling the image light from the waveguide substrate and finally transmitted to human eyes. Therefore, the manufacturing device can expose three areas on the holographic dry plate 80 at the same time, so that the holographic grating has a grating structure of the three areas, and is simple to operate, high in manufacturing efficiency, low in cost and high in yield. The prepared holographic optical waveguide has high diffraction efficiency, is applied to near-eye display equipment, and can remarkably improve the field angle and the eye movement range and simultaneously reduce the volume of the optical machine. It can be understood that, in the holographic optical waveguide manufactured by the manufacturing device, the coupling-in grating and the coupling-out grating are both reflection type volume holographic gratings, and the turning grating is a transmission type volume holographic grating. Reflective volume holographic gratings typically have higher diffraction efficiencies and larger angular bandwidths than transmissive volume holographic gratings. In addition, based on the holographic grating exposure following the K vector algorithm, taking the reflective incoupling volume holographic grating as an example, the reflective incoupling volume holographic grating exposure made by the making device follows the K vector algorithm. Referring to FIG. 3, K1 represents the wave vector incident on the holographic material from air, and K2 represents the wave vector incident on the holographic material from within the waveguide substrate; assuming that the refractive index of the waveguide substrate and the refractive index of the holographic material are both n, the wavelength of the exposure light is λ, the grating period formed by interference exposure is D, the grating fringe interval period is Λ, the fringe inclination angle is ζ, and the grating vector K is perpendicular to the grating fringes, the modes of the wavevectors K1 and K2 of the first light beam L1 and the second light beam L2 are 2 π n/λ, and the mode of the grating vector K is 2 π n/Λ, which form a closed vector triangle and satisfy K = K1-K2, then, in a subsequent application, when the incident light satisfies the bragg condition Λ = λ/(2ncos (ζ)) of the incoupling holographic grating, the incoupling holographic grating has the highest diffraction efficiency. Therefore, the holographic optical waveguide manufactured by the manufacturing device has higher diffraction efficiency.

In some embodiments, referring to fig. 2, in the manufactured holographic optical waveguide, the first region where the coupling grating 81 is located may be circular, and the second region where the coupling grating 82 is located and the third region where the turning grating 83 is located may be rectangular. In practical applications, the first region, the second region and the third region may be circular, rectangular, polygonal, or other regular patterns, irregular patterns, etc., and the limitation in this embodiment is not required. In addition, the third region has at least three sides, the first region is located at a first side of the third region, the second region is located at a second side of the third region, and a line connecting a center of the first region and a center of the third region is perpendicular to a line connecting a center of the second region and a center of the third region. In practical applications, the positions and sizes of the first region, the second region and the third region may be set according to actual needs, and the limitation in this embodiment is not required.

In practical applications, the holographic optical waveguide having only the in-coupling grating and the out-coupling grating may be manufactured by using only the first light beam and the second light beam to coherently form the in-coupling grating in the first area of the holographic stem plate, and using the third light beam and the fifth light beam to coherently form the out-coupling grating in the second area of the holographic stem plate. For example, the fourth light beam and the sixth light beam are blocked by the baffles respectively, so that the fourth light beam and the sixth light beam cannot be incident on the holographic dry plate, and thus, the holographic optical waveguide only provided with the coupling-in grating and the coupling-out grating can be manufactured.

In the manufacturing process, various holographic optical waveguides can be manufactured by changing exposure parameters, wherein the exposure parameters comprise the number of wavelengths of exposure light, an exposure angle, and the position and the size of an exposure area. The wavelength of the exposure light may include at least one wavelength in the visible wavelength range; the exposure angle includes three pairs of exposure beam angles, as shown in fig. 1, the first pair of exposure beam angles includes an incident angle of the first light beam L1 to the holographic dry plate 80 and an incident angle of the second light beam L2 to the holographic dry plate 80, the second pair of exposure beam angles includes an incident angle of the third light beam L3 to the holographic dry plate 80 and an incident angle of the fifth light beam L5 to the holographic dry plate 80, and the third pair of exposure beam angles includes an incident angle of the fourth light beam L4 to the holographic dry plate 80 and an incident angle of the sixth light beam L6 to the holographic dry plate 80; the position and size of the exposure area include the position and size of the first area, the position and size of the second area, and the position and size of the third area. It should be noted that the exposure beam angles may be considered to be different if only one of the pair of exposure beam angles has a different incident angle.

Optionally, in the manufacturing process, if the holographic dry plate 80 is exposed only once by using light with one wavelength, a holographic interference fringe corresponding to the wavelength of the exposure light is formed on the first area, the second area and the third area of the holographic dry plate 80, that is, the coupling-in grating of the first area, the coupling-out grating of the second area and the turning grating of the third area on the holographic optical waveguide have a periodic refractive index modulation structure corresponding to the wavelength of the exposure light. The holographic optical waveguide prepared by the method can be used for preparing a monochromatic holographic optical waveguide and can realize the coupling-in, turning and coupling-out of incident light corresponding to the wavelength of exposure light.

In the coupled-in grating, the coupled-out grating and the turning grating formed by exposure of exposure light with the same wavelength, the included angle alpha of the grating lines of the coupled-in grating and the coupled-out grating is 90 degrees +/-30 degrees, the included angle alpha of the coupled-in grating and the grating lines of the turning grating is alpha/2, or the included angle alpha of the coupled-out grating and the grating lines of the turning grating is alpha/2, and the fringe period Lambda 1 of the coupled-in grating, the fringe period Lambda 2 of the coupled-out grating and the fringe period Lambda 3 of the turning grating satisfy the following relational expression:

Λ1=Λ2；

Λ3=Λ1/(2cos(α/2))。

optionally, in the manufacturing process, if only N light beams with different wavelengths are used to expose one holographic dry plate at the same time, N types of holographic interference fringes corresponding to the N different wavelengths are respectively formed in the first area, the second area, and the third area of the holographic dry plate, that is, N types of refractive index modulation structures corresponding to the N different wavelengths are respectively provided in the coupling-in grating, the coupling-out grating, and the turning grating of the manufactured holographic optical waveguide, so as to obtain a wavelength-multiplexed holographic optical waveguide, where N is an integer greater than or equal to 2. Then, when the N light beams with different wavelengths used for the corresponding exposure are combined and then incident into the wavelength-multiplexed holographic optical waveguide, the wavelength-multiplexed holographic optical waveguide can simultaneously couple in the N light beams with different wavelengths, and expand and couple out the light beams, thereby realizing the wavelength multiplexing function.

In the same area of the wavelength multiplexing holographic optical waveguide, for different holographic interference fringes formed by N light rays with different wavelengths under the same group of exposure angles, the grating vector directions corresponding to the holographic interference fringes are the same, namely the holographic interference fringes have the same fringe inclination angle. In the coupling-in grating, the coupling-out grating and the turning grating, the refractive index modulation structures with N fringe periods are respectively arranged; in addition, the stripe inclination angles of the N refractive index modulation structures in the coupling-in grating are the same, the stripe inclination angles of the N refractive index modulation structures in the coupling-out grating are the same, and the stripe inclination angles of the N refractive index modulation structures in the turning grating are the same. The fringe period of these holographic interference fringes is wavelength dependent.

Specifically, when the beams of red light, green light and blue light are combined and simultaneously exposed, as shown in fig. 4, the coupling-in grating, the coupling-out grating and the turning grating of the holographic optical waveguide are respectively provided with a holographic interference fringe R obtained by exposing corresponding to red light, a holographic interference fringe G obtained by exposing corresponding to green light and a holographic interference fringe B obtained by exposing corresponding to blue light, that is, three refractive index modulation structures corresponding to red light, green light and blue light are respectively formed on the coupling-in grating, the coupling-out grating and the turning grating on the manufactured holographic optical waveguide, so that the holographic optical waveguide with wavelength multiplexing is obtained, and wavelength multiplexing can be realized for the light with three wavelengths of red light, green light and blue light. For example, when the incident light is an RGB light source, i.e., when the incident light includes red light, green light, and blue light at the same time, the incoupling grating of the wavelength-multiplexed holographic optical waveguide can simultaneously couple the red light, the green light, and the blue light into the waveguide substrate and make the incoupling light propagate toward the turning grating; then, the turning grating can simultaneously expand the red light, the green light and the blue light and simultaneously transmit the red light, the green light and the blue light to the coupling grating; finally, the coupling-out grating can simultaneously expand red light, green light and blue light and simultaneously couple the red light, the green light and the blue light out of the waveguide substrate, namely the red light, the green light and the blue light are matched with different Bragg conditions to be diffracted in the wavelength-multiplexed holographic optical waveguide, thereby realizing full-color display. In addition, in the exposure process, the diffraction efficiency of the grating of each area on the holographic optical waveguide to the three-color light beams of red light, green light and blue light can be approximately the same by adjusting the laser energy ratio of the red light, the green light and the blue light, so that the rainbow effect is inhibited. Compared with the scheme of realizing full-color display by adopting a single-layer array two-dimensional optical waveguide and adopting a double-layer or three-layer embossed grating waveguide, the manufacturing device provided by the invention has low manufacturing cost and high yield in manufacturing the full-color holographic optical waveguide.

Referring to fig. 4, in the same area of the wavelength-multiplexed holographic optical waveguide, under the same set of exposure angles, the grating vectors corresponding to the holographic interference fringes corresponding to the red light, the holographic interference fringes corresponding to the green light, and the holographic interference fringes corresponding to the blue light have the same directions, i.e., have the same fringe tilt angles, but the corresponding fringe periods are Λ, respectively_R、Λ_GAnd Λ_B(ii) a It can be seen that the fringe periods between the holographic interference fringes formed by exposure to light of different wavelengths in the same region are not equal.

Optionally, in the manufacturing process, if light with the same wavelength is used to expose one holographic plate for M times at M groups of exposure angles, M kinds of holographic interference fringes corresponding to the M groups of exposure angles are respectively formed in the first region, the second region, and the third region of the holographic plate. In the coupling grating on the holographic optical waveguide, M kinds of holographic interference fringes corresponding to M groups of first pair of exposure beam angles are formed; in the coupling grating on the holographic optical waveguide, at least M kinds of holographic interference fringes corresponding to M groups of second pair of exposure beam angles are formed; and in the turning grating on the holographic optical waveguide, M holographic interference fringes corresponding to M groups of third pair of exposure beam angles are formed, so that the angle-multiplexed holographic optical waveguide is obtained, wherein M is an integer greater than or equal to 2, and the exposure beam angles in each pair of M groups of exposure angles are different.

In the same area of the angle-multiplexed holographic optical waveguide, for M different kinds of holographic interference fringes formed by light rays with the same wavelength under M groups of different exposure angles, the holographic interference fringes have the same fringe period and different fringe inclination angles. For example, the light with the same wavelength is used to expose the holographic dry plate for three times at three exposure angles, and the obtained coupling-in grating, coupling-out grating and turning grating on the holographic optical waveguide respectively have three holographic interference fringes corresponding to the three exposure angles. As shown in fig. 5, three kinds of holographic interference fringes corresponding to three sets of exposure angles are formed in a certain area, and the three sets of holographic interference fringes have the same fringe period, which is D, but have different fringe inclination angles, which are ζ 1, ζ 2, and ζ 3, respectively.

It can be understood that, with respect to the manufactured angle-multiplexed hologram optical waveguide, when light rays having wavelengths corresponding to those used in exposure are incident into the angle-multiplexed hologram optical waveguide, the angle-multiplexed hologram optical waveguide has high diffraction efficiency even if the light rays are incident into the angle-multiplexed hologram optical waveguide at a large angle, thereby achieving angle multiplexing and good large-field display.

Optionally, in the manufacturing process, if light beams with different wavelengths are used to expose the holographic dry plate at different exposure angles, a holographic optical waveguide with angle multiplexing and wavelength multiplexing functions can be obtained. It can be understood that when a light beam composed of N light beams with different wavelengths is used to expose a holographic dry plate M times at M groups of different exposure angles, N × M holographic interference fringes are formed on the first region, the second region and the third region of the holographic dry plate, i.e. N × M periodic refractive index modulation structures are respectively formed in the coupling-in grating, the coupling-out grating and the turning grating of the manufactured holographic optical waveguide, and the holographic optical waveguide manufactured by this way can be obtained.

In some embodiments, referring to fig. 1, the first beam splitter unit 20 includes a first beam splitter 21 and a second beam splitter 22. The light incident side of the first beam splitter 21 is disposed on the light emergent side of the light source, the light incident side of the second beam splitter 22 is disposed on the first light emergent side of the first beam splitter 21, the second beam splitter unit 30 is disposed on the second light emergent side of the first beam splitter 21, the second reflection unit 50 is disposed on the first light emergent side of the second beam splitter 22, and the third reflection unit 60 is disposed on the second light emergent side of the second beam splitter 22.

Specifically, the light incident side of the first beam splitter 21 is disposed in the propagation direction of the first light beam M1, the first light beam M1 and the first light beam L1 both propagate in the first direction, the first beam splitter 21 is configured to split the first light beam M1 into a third light beam propagating in the first direction and a second light beam M2 propagating in the second direction, and the second beam splitter 22 is configured to split the third light beam into a second light beam L2 propagating in the first direction and a third light beam L3 propagating in the third direction. The spectroscope is a coated glass, and one or more layers of thin films are coated on the surface of the optical glass, so that after a beam of light is projected on the coated glass, the beam of light can be divided into a plurality of beams of light through reflection and transmission. The beam splitter is used for splitting an incident light beam into a transmitted light and a reflected light with a certain light intensity ratio. In practical applications, a fixed splitting ratio beam splitter and a variable splitting ratio beam splitter may be selected, and are not limited herein.

In some embodiments, with continued reference to fig. 1, the second reflecting unit 50 may include a first reflecting mirror; the first reflector is disposed on the first light-emitting side of the first light splitting unit 20, and the first surface of the holographic plate 80 is disposed in the reflection direction of the first reflector. The first mirror is used to reflect the second light beam L2 to a first area of the first side of the holographic plate 80.

Optionally, the first mirror is fixed on a slide rail rotation table, and the slide rail rotation table can drive the first mirror to translate and rotate. Specifically, this slide rail revolving stage can drive first speculum at slide rail revolving stage place plane, move along the direction that is on a parallel with holographic dry plate 80's first face, in addition, this slide rail revolving stage can drive first speculum and rotate around the center of first speculum, drive first speculum through the slide rail revolving stage and carry out translation and rotation, can change the incident angle of second light beam L2 and holographic dry plate 80's first region, thereby can let holographic dry plate 80's first region exposed with different incident angles by second light beam L2.

In some embodiments, with continued reference to fig. 1, the third reflecting unit 60 includes a second mirror 61 and a third mirror 62; the second reflecting mirror 61 is disposed on the second light-emitting side of the first light splitting unit 20, the third reflecting mirror 62 is disposed in the reflecting direction of the second reflecting mirror 61, and the first surface of the holographic plate 80 is disposed in the reflecting direction of the third reflecting mirror 62. Specifically, the second reflecting mirror 61 is disposed on the second light-exiting side of the second beam splitter 22, the second reflecting mirror 61 is configured to reflect the third light beam L3 to the third reflecting mirror 62, and the third reflecting mirror 62 is configured to reflect the third light beam L3 to the second area of the first surface of the holographic plate 80.

Optionally, the third mirror 62 is fixed to a slide-rotating stage, which can translate and rotate the third mirror 62. Specifically, the sliding track rotating table can drive the third reflecting mirror 62 to move along the direction parallel to the first surface of the holographic dry plate 80 on the plane where the sliding track rotating table is located, in addition, the sliding track rotating table can drive the third reflecting mirror 62 to rotate around the center of the third reflecting mirror 62, the sliding track rotating table drives the third reflecting mirror 62 to translate and rotate, the incident angle of the third light beam L3 and the second area of the holographic dry plate 80 can be changed, and therefore the second area of the holographic dry plate 80 can be exposed by the third light beam L3 at different incident angles.

In some embodiments, referring to fig. 1, the first reflecting unit 40 includes a fourth reflecting mirror 41 and a fifth reflecting mirror 42; the fourth reflector 41 is disposed on the light emitting side of the light source 10, the fifth reflector 42 is disposed in the reflecting direction of the fourth reflector 41, and the first incident surface of the irregular prism 70 is disposed in the reflecting direction of the fifth reflector 42. Specifically, the fourth mirror 41 is disposed in the propagation direction of the first light beam L1, the fourth mirror 41 is configured to reflect the first light beam L1 to the fifth mirror 42, and the fifth mirror 42 is configured to reflect the first light beam L1 to the first area of the second surface of the holographic plate 80.

Optionally, the fifth mirror 42 is fixed to a slide-on-rotation stage, which translates and rotates the fifth mirror 42. Specifically, the sliding track rotating table can drive the fifth reflecting mirror 42 to move along the direction perpendicular to the first surface of the holographic plate 80 on the plane where the sliding track rotating table is located, in addition, the sliding track rotating table can drive the fifth reflecting mirror 42 to rotate around the center of the fifth reflecting mirror 42, the sliding track rotating table drives the fifth reflecting mirror 42 to translate and rotate, the incident angles of the first light beam L1 and the second area of the holographic plate 80 can be changed, and therefore the second area of the holographic plate 80 can be exposed by the first light beam L1 at different incident angles.

In some embodiments, referring to fig. 1, the second beam splitting unit 30 includes a third beam splitter 31, a sixth reflector 32, and a seventh reflector 33; the light incident side of the third beam splitter 31 is disposed on the third light emitting side of the first beam splitter unit 20, the second incident surface of the special-shaped prism 70 is disposed on the first light emitting side of the third beam splitter 31, the sixth reflector 32 is disposed on the second light emitting side of the third beam splitter 31, the seventh reflector 33 is disposed in the reflection direction of the sixth reflector 32, and the third incident surface of the special-shaped prism 70 is disposed in the reflection direction of the seventh reflector 33. Specifically, the light-in side of the third beam splitter 31 is disposed on the second light-out side of the first beam splitter 21, and the third beam splitter 31 is configured to split the second light M2 into a fourth light beam L4, a fifth light beam L5, and a sixth light beam L6, reflect the fourth light beam L4 to the second incident surface of the special-shaped prism 70, and transmit the fifth light beam L5 and the sixth light beam L6 to the sixth reflector 32; the sixth mirror 32 is configured to reflect the fifth light beam L5 and the sixth light beam L6 to the seventh mirror 33, and the seventh mirror 33 is configured to reflect the fifth light beam L5 and the sixth light beam L6 to the third incident surface of the special-shaped prism 70.

Alternatively, the seventh mirror 33 may be fixed to a sled rotation stage, which may translate and rotate the seventh mirror 33. Specifically, the sliding track rotating table can drive the seventh reflecting mirror 33 to move along a direction parallel to the first surface of the holographic plate 80 on the plane where the sliding track rotating table is located, in addition, the sliding track rotating table can drive the seventh reflecting mirror 33 to rotate around the center of the seventh reflecting mirror 33, the sliding track rotating table drives the seventh reflecting mirror 33 to translate and rotate, the incident angle between the fifth light beam L5 and the second area of the holographic plate 80 and the incident angle between the sixth light beam L6 and the third area of the holographic plate 80 can be changed, and therefore the second area of the holographic plate 80 can be exposed by the fifth light beam L5 at different incident angles, and the third area can be exposed by the sixth light beam L6 at different incident angles.

Alternatively, the third spectroscope 31 may be fixed to a slide rail rotation table, which may drive the third spectroscope 31 to translate and rotate. Specifically, this slide rail revolving stage can drive third spectroscope 31 at slide rail revolving stage place plane, move along the direction of the first face of perpendicular to holographic dry plate 80, in addition, this slide rail revolving stage can drive third spectroscope 31 and rotate around the center of third spectroscope 31, drive third spectroscope 31 through the slide rail revolving stage and carry out translation and rotation, can change the incident angle of fourth light beam L4 and holographic dry plate 80's third region, thereby can let holographic dry plate 80's third region exposed with different incident angles by fourth light beam L4.

In practical applications, the plane mirror fixed on the slide rail rotation stage can be freely disposed, and the limitation in the above embodiments is not required. By fixing the plane mirror which needs to translate or rotate in the sliding rail rotating table, the exposure position and the exposure angle can be changed, so that various types of holographic optical waveguides can be manufactured.

Specifically, in some embodiments, referring to fig. 6 and 7, the irregular prism 70 may have six surfaces, including a first incident surface, a second incident surface, a third incident surface and an exit surface; in the special-shaped prism 70, the first light beam L1 directly passes through the first incident surface to reach the emergent surface, and is emergent to the first area of the second surface of the holographic dry plate at the emergent surface; the fourth light beam L4 directly passes through the second incident surface to reach the emergent surface, and is emergent to the third area of the second surface of the holographic plate at the emergent surface; the fifth light beam L5 directly passes through the third incident surface to reach the emergent surface, and is emergent to the second area of the second surface of the holographic plate at the emergent surface; the sixth light beam L6 passes directly through the third entrance face to the exit face where it exits to the third area of the second face of the holographic plate.

In some embodiments, referring to fig. 8 and 9, the shaped prism 70 may further include a reflection surface for totally reflecting the fifth light beam L5 and the sixth light beam L6 to the exit surface, and exiting to the second surface of the holographic plate 80 through the exit surface. Specifically, the special-shaped prism 70 is configured to receive the fifth light beam L5 and the sixth light beam L6 through the third incident surface, and reflect the fifth light beam L5 and the sixth light beam L6 through the reflecting surface to the exit surface, so that the fifth light beam L5 and the sixth light beam L6 are respectively emitted to the second area and the third area of the second surface of the holographic dry plate 80 through the exit surface. In practical application, the special-shaped prism 70 has more than four smooth light-passing surfaces, and the light path of each light beam in the special-shaped prism 70 can be set according to actual needs, but it should be noted that each light beam should satisfy the total reflection condition when being reflected by the reflecting surface in the special-shaped prism 70.

In some of these embodiments, the light source 10 may include at least one laser and a beam combiner 14; each laser is disposed at each input end of the beam combiner 14, and the first reflection unit 40 and the first light splitting unit 20 are both disposed at the output end of the beam combiner 14. Specifically, the first reflection unit 40 is disposed at the output end of the beam combiner 14 and disposed in the propagation direction of the first light beam L1, and the first light splitting unit 20 is disposed at the output end of the beam combiner 14 and disposed in the propagation direction of the first light beam M1.

Optionally, the beam combiner 14 may be an X-prism, and is formed by gluing four right-angle prisms, and a first dichroic film and a second dichroic film that are orthogonal to each other are respectively disposed on diagonal surfaces of the X-prism, where the first dichroic film is a dichroic film that reflects red light, transmits green light, and transmits blue light, and the second dichroic film is a dichroic film that reflects blue light, transmits red light, and transmits green light. The combiner 14 may also be other suitable spectrum combining devices, and need not be limited to the embodiment.

Further, in some embodiments, referring to fig. 10, the light source 10 may include a red laser 11, a green laser 13, a blue laser 12, and a beam combiner 14, and the beam combiner 14 may combine red light emitted from the red laser 11, green light emitted from the green laser 13, and blue light emitted from the blue laser 12 into a beam of laser output. In practical applications, the arrangement of the lasers and the structure of the beam combining prism can be set according to actual needs, and the limitation in this embodiment is not required.

In some embodiments, with continued reference to fig. 10, the manufacturing apparatus may further include a polarization splitting prism 91. The incident end of the polarization beam splitter prism 91 is disposed at the output end of the beam combiner 14, and the first reflection unit 40 and the first beam splitting unit 20 are both disposed at the exit end of the polarization beam splitter prism 91. Specifically, the first reflection unit 40 is disposed at the exit end of the polarization beam splitter 91 and in the propagation direction of the first light beam L1, and the first beam splitter unit 20 is disposed at the exit end of the polarization beam splitter 91 and in the propagation direction of the first light beam M1. The polarization splitting prism 91 is used to emit the light emitted from the light source 10 in a first polarization state (e.g., S polarization state). Specifically, the entrance surface and the exit surface of the polarization beam splitter prism 91 are disposed adjacent to each other. When the light from the light source 10 enters through the incident surface of the polarization beam splitter prism 91, the light in the S-polarization state exits through the exit surface of the polarization beam splitter prism 91, and the light in the P-polarization state is transmitted through the polarization beam splitter prism 91. The light used for subsequent exposures is only light in the S polarization state, which can filter the light.

In some embodiments, with continued reference to fig. 10, the manufacturing apparatus further includes a spatial filter 92 and a collimating unit 93; the light-in side of the spatial filter 92 is disposed at the light-out side of the polarization beam splitter 91, the light-in side of the collimating unit 93 is disposed at the light-out side of the spatial filter 92, and the first reflecting unit 40 and the first beam splitter unit 20 are both disposed at the light-out side of the collimating unit 93. The first reflecting unit 40 is disposed on the light-emitting side of the collimating unit 93 and in the propagation direction of the first light beam L1, and the first light splitting unit 20 is disposed on the light-emitting side of the collimating unit 93 and in the propagation direction of the first light beam M1. Specifically, the first beam splitter 21 is disposed on the light exit side of the collimating unit 93 and in the propagation direction of the first light beam M1, and the fourth reflector 41 is disposed on the light exit side of the collimating unit 93 and in the propagation direction of the first light beam L1. Wherein the spatial filter 92 is used to diverge the light and the collimating unit 93 is used to collimate the light. Thus, after the light is diffused by the spatial filter 92, the diffused light beam is collimated by the collimating unit 93 to ensure the collimation of the diffused light beam, thereby obtaining a parallel light beam with a large diameter.

Next, the working process of the apparatus for manufacturing a holographic optical waveguide according to the embodiment of the present invention will be described in detail with reference to the embodiment shown in fig. 10, wherein the second surface of the holographic dry plate 80 is attached to the exit surface of the special-shaped prism 70, for example, by using a liquid material such as a matching fluid; the collimating unit 93 may be a collimating lens.

At this time, the red light emitted by the red laser 11 reaches the beam combiner 14 through the first incident surface of the beam combiner 14, the green light emitted by the green laser 13 reaches the beam combiner 14 through the second incident surface of the beam combiner 14, and the blue light emitted by the blue laser 12 reaches the beam combiner 14 through the third incident surface of the beam combiner 14; then, the beam combiner 14 combines the red light, the blue light and the green light into a laser beam and outputs the laser beam to the polarization beam splitter prism 91, and the polarization beam splitter prism 91 filters the light component in the P polarization state in the light beam and outputs the light component in the S polarization state to the spatial filter 92; then, the spatial filter 92 outputs the light rays as divergent light to the collimator lens, which changes the divergent light into parallel light of a large diameter including the first light ray M1 and the first light beam L1 parallel to each other.

The first light beam L1 is directly reflected by the fourth mirror 41 to the fifth mirror 42, then reflected by the fifth mirror 42, passes through the first incident surface and the exit surface of the shaped prism 70, and then illuminates the first area of the second surface of the holographic plate 80.

The first light beam M1 is split into a second light beam M2 and a third light beam by the first beam splitter 21; the third light beam passes through the first beam splitter 21, passes through the second beam splitter 22, and is divided into a second light beam L2 and a third light beam L3, the second light beam L2 passes through the second beam splitter 22 to reach the first reflector, and then is reflected by the first reflector to the first area of the first surface of the holographic dry plate 80; the third light beam L3 is reflected by the second beam splitter 22 to the second reflecting mirror 61 and by the second reflecting mirror 61 to the second area of the first surface of the holographic plate 80.

The second light beam M2 is reflected by the first beam splitter 21 to the third beam splitter 31, and is divided into a fourth light beam L4, a fifth light beam L5 and a sixth light beam L6 after passing through the third beam splitter 31, and the fourth light beam L4 is reflected by the third beam splitter 31 to the second incident surface of the special-shaped prism 70, and exits to the third area of the second surface of the holographic dry plate 80 through the exit surface of the special-shaped prism 70; the fifth light beam L5 is transmitted to the sixth reflecting mirror 32 through the third beam splitter 31, reflected to the seventh reflecting mirror 33 by the sixth reflecting mirror 32, reflected to the third incident surface of the special-shaped prism 70 by the seventh reflecting mirror 33, and emitted to the second area of the second surface of the holographic dry plate 80 through the exit surface of the special-shaped prism 70; the sixth light beam L6 is transmitted to the sixth reflecting mirror 32 through the third beam splitter 31, reflected to the seventh reflecting mirror 33 by the sixth reflecting mirror 32, reflected to the third incident surface of the special-shaped prism 70 by the seventh reflecting mirror 33, and emitted to the third area of the second surface of the holographic plate 80 through the exit surface of the special-shaped prism 70. It should be noted that the first area of the first surface corresponds to the first area of the second surface, and the second area of the first surface corresponds to the second area of the second surface, so that the first light beam L1 and the second light beam L2 can interfere in the first area of the holographic plate 80, and the first area of the holographic plate 80 is exposed by the holographic interference fringes formed by the first light beam L1 and the second light beam L2, thereby forming the incoupling grating; the third light beam L3 and the fifth light beam L5 may interfere at a second region of the holographic stem plate 80, the second region of the holographic stem plate 80 being exposed by holographic interference fringes formed by the third light beam L3 and the fifth light beam L5, thereby forming an out-coupling grating; the fourth light beam L4 and the sixth light beam L6 may interfere in a third region of the holographic dry plate 80, the third region of the holographic dry plate 80 being exposed by holographic interference fringes formed by the fourth light beam L4 and the sixth light beam L6, thereby forming a turning grating; after exposure, the holographic plate 80 is transformed to form a holographic optical waveguide.

In the manufacturing device, the holographic optical waveguides with different styles can be manufactured by adjusting the positions and the angles of the first reflector, the third reflector 62, the fifth reflector 42, the seventh reflector 33 and the third beam splitter 31 through the slide rail rotating table, and the manufacturing device has the advantages of simple operation, low cost and high yield. The manufactured holographic optical waveguide is provided with the coupling-in grating on the first area, the coupling-out grating on the second area and the turning grating on the third area, so that light can be expanded and transmitted along different directions; moreover, by changing the wavelength of the laser, the laser with different wavelengths can be synthesized into a beam of light to expose the holographic dry plate, so that the wavelength-multiplexed holographic optical waveguide is obtained; or, by changing the incident angle of each light beam, coherent light can be coherent at different incident angles, so that the angle-multiplexed holographic optical waveguide can be obtained; therefore, the diffraction efficiency of light is improved, the optical-mechanical-fiber-array-based near-eye display device can be applied to near-eye display equipment, the field angle and the eye movement range can be obviously improved, and the size of the optical-mechanical device is reduced.

In order to improve the uniformity of the energy distribution of the optical waveguide, in some embodiments, the manufacturing apparatus further includes at least one gradual attenuation sheet or at least one movable baffle, where the gradual attenuation sheet is disposed in at least one of the optical paths of the third light beam L3, the fourth light beam L4, the fifth light beam L5, and the sixth light beam L6; likewise, the movable barrier may be disposed in at least one of the optical paths of the third, fourth, fifth and sixth light beams L3, L4, L5 and L6. By arranging the gradual attenuation sheet or the movable baffle, the diffraction efficiency distribution of the coupled-out grating of the holographic optical waveguide in the second area can show a gradual change rule, and/or the diffraction efficiency distribution of the turning grating of the holographic optical waveguide in the third area can show a gradual change rule. For example, the diffraction efficiency of the turning grating from the side close to the coupling-in grating to the side far from the coupling-in grating tends to gradually increase, and the diffraction efficiency of the coupling-out grating from the side close to the turning grating to the side far from the turning grating tends to gradually increase, which may be beneficial to the uniform distribution of light in the whole waveguide region.

In some embodiments, the manufacturing apparatus further comprises at least one stop, and the shape of the light beam can be modified by arranging the stop on the light path before one or more of the first light beam L1 to the sixth light beam L6 enters the profile prism 70.

In some embodiments, the apparatus further includes a baffle disposed between the optical paths of the fifth light beam L5 and the sixth light beam L6 and disposed parallel to the propagation direction of the fifth light beam L5 and the sixth light beam L6, for example, the baffle is disposed perpendicular to the surface of the sixth mirror 32 and disposed on the sixth mirror 32, and by disposing the baffle, the crosstalk between the fifth light beam L5 and the sixth light beam L6 can be avoided. In practical applications, the stop may also be disposed on the optical path of the fifth light beam and the sixth light beam to avoid crosstalk between the fifth light beam and the sixth light beam.

In a second aspect, an embodiment of the present invention further provides a holographic optical waveguide obtained by the manufacturing apparatus in any one of the first aspect, where the holographic optical waveguide is an angle-multiplexing and/or wavelength-multiplexing holographic optical waveguide. By the manufacturing device shown in the first aspect, a wavelength-multiplexed and/or angle-multiplexed holographic optical waveguide can be manufactured, so that angle multiplexing and/or wavelength multiplexing can be realized, the field angle and the eye movement range can be remarkably improved, and the volume of an optical machine can be reduced.

In some embodiments, in the wavelength-multiplexed holographic optical waveguide, the incident grating, the outgoing grating and the turning grating formed by exposing light with the same wavelength at the same exposure angle are formed, an included angle α between grating lines of the incident grating and the outgoing grating is 90 ° ± 30 °, an included angle between grating lines of the incoming grating and the turning grating is α/2, or an included angle between grating lines of the outgoing grating and the turning grating is α/2.

Further, in some of the embodiments, in the wavelength-multiplexed hologram optical waveguide, Λ 1, the fringe period Λ 1 of the outcoupling grating, and the fringe period Λ 3 of the turning grating satisfy the following relationship:

Λ1=Λ2；

Λ3=Λ1/(2cos(α/2))。

in some embodiments, the turning grating has at least three sides, the coupling grating is located at a first side of the turning grating, the coupling grating is located at a second side of the turning grating, and a connection line between a center of the coupling grating and a center of the turning grating is perpendicular to a connection line between the center of the coupling grating and the center of the turning grating.

In a third aspect, embodiments of the present invention further provide a near-eye display device, including at least one layer of the holographic optical waveguide according to any one of the second aspects. The holographic optical waveguide in the near-to-eye display equipment can realize wavelength multiplexing and/or angle multiplexing, and can reduce the volume of an optical machine while remarkably improving the field angle and the eye movement range.

In some of these embodiments, the near-eye display device includes a layer of holographic optical waveguide that is a wavelength-multiplexed and angle-multiplexed holographic optical waveguide. Specifically, in the incoupling grating, the outcoupling grating and the turning grating of the holographic optical waveguide, in the manufacturing process, when a beam formed by combining N light beams with different wavelengths is respectively exposed on one holographic dry plate at M groups of different exposure angles by using the manufacturing device according to the first aspect, N × M holographic interference fringes are respectively formed on the first region, the second region and the third region, so that the incoupling grating, the outcoupling grating and the turning grating respectively have N × M periodic refractive index modulation structures, thereby obtaining the holographic optical waveguide with both angle multiplexing and wavelength multiplexing. In practical applications, the manufacturing apparatus and the manufacturing parameters can be selected according to actual needs, and are not limited herein.

Specifically, in order to realize full-color display, in the manufacturing process, the manufacturing apparatus according to the first aspect may be used, light beams formed by combining three light beams with different wavelengths, i.e., red light, green light, and blue light, are used to expose a holographic plate for M times at M groups of different exposure angles, and 3 × M holographic interference fringes are respectively formed in the first region, the second region, and the third region, so that the incoupling grating, the outcoupling grating, and the turning grating respectively have 3 × M periodic refractive index modulation structures, thereby obtaining a holographic optical waveguide multiplexing wavelengths of the three light beams, i.e., red light, green light, and blue light, and the holographic optical waveguide has an angle multiplexing function.

Then, when light with red, green and blue wavelengths is incident to the holographic optical waveguide of the near-eye display device, the holographic optical waveguide can simultaneously couple in, turn and couple out the red, green and blue light, thereby realizing full-color display; in addition, when the light rays of the red light, the green light and the blue light are incident at a large angle, the holographic optical waveguide of the near-eye display device has an angle multiplexing function, so that the holographic optical waveguide can still have high diffraction efficiency on the light rays, and large-field display is realized.

In order to further improve the diffraction efficiency of the near-eye display device, in some embodiments, the near-eye display device includes M layers of holographic optical waveguides, where the M layers of holographic optical waveguides are all wavelength-multiplexed holographic optical waveguides, and the M layers of holographic optical waveguides respectively correspond to M groups of different exposure angles; or the near-eye display device comprises N layers of holographic optical waveguides, wherein the N layers of holographic optical waveguides are angle multiplexing holographic optical waveguides, the N layers of holographic optical waveguides correspond to N different exposure wavelengths respectively, M is an integer greater than or equal to 2, and N is an integer greater than or equal to 2.

In particular, to achieve a full color display, in some embodiments, the near-eye display device includes M holographic optical waveguides, and each holographic optical waveguide is a wavelength-multiplexed holographic optical waveguide; that is, the light beams formed by combining the red light, the green light and the blue light are respectively exposed to M holographic dry plates at M groups of different exposure angles to obtain M holographic optical waveguides, wherein each holographic dry plate corresponds to one group of exposure angles. Thus, after the M holographic optical waveguides are arranged in a bonding mode, full-color large-view-field display can be achieved.

In other embodiments, referring to fig. 11, the near-eye display device includes three holographic optical waveguides, a first holographic optical waveguide 1, a second holographic optical waveguide 2, and a third holographic optical waveguide 3, and each holographic optical waveguide is an angularly multiplexed holographic optical waveguide. Illustratively, a first holographic dry plate is exposed for M times by adopting red light at M groups of different exposure angles to obtain a first holographic optical waveguide 1, a second holographic optical waveguide 2 is exposed for M times by adopting green light at M groups of different exposure angles to obtain a second holographic dry plate, and a third holographic optical waveguide 3 is exposed for M times by adopting blue light at M groups of different exposure angles to obtain a third holographic optical waveguide; then, the first holographic optical waveguide 1 is an angle-multiplexed holographic optical waveguide corresponding to red light, the second holographic optical waveguide 2 is an angle-multiplexed holographic optical waveguide corresponding to green light, and the third holographic optical waveguide 2 is an angle-multiplexed holographic optical waveguide corresponding to blue light. In this way, a full-color large-field display can be similarly realized even when the first hologram light guide 1, the second hologram light guide 2, and the third hologram light guide 3 are disposed in a laminated manner.

In summary, the embodiment of the present invention provides a holographic optical waveguide, a manufacturing apparatus thereof, and a near-eye display device, wherein the manufacturing apparatus of the holographic optical waveguide includes a light source, a first light splitting unit, a second light splitting unit, a first reflection unit, a second reflection unit, a third reflection unit, a special-shaped prism, and a holographic dry plate; through the light source, the light splitting units, the reflecting units and the special-shaped prism, the first area of the holographic dry plate is coherent by the first light beam and the second light beam to form an incoupling grating, the second area is coherent by the third light beam and the fifth light beam to form an outcoupling grating, and the third area is coherent by the fourth light beam and the sixth light beam to form a turning grating, so that the holographic optical waveguide is obtained. The manufacturing device enables the holographic dry plate to form the grating structure in three areas simultaneously, so that the holographic optical waveguide is manufactured, the operation is simple, the manufacturing efficiency is high, the cost is low, the yield is high, the manufactured holographic optical waveguide is applied to near-to-eye display equipment, the light diffraction efficiency can be improved, the visual angle and the eye movement range can be obviously improved, and the size of an optical machine can be reduced.

It should be noted that the above-described device embodiments are merely illustrative, where the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; within the idea of the invention, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for making a holographic optical waveguide, comprising: the holographic optical system comprises a light source, a first light splitting unit, a second light splitting unit, a first reflecting unit, a second reflecting unit, a third reflecting unit, a special-shaped prism and a holographic dry plate;

the first reflection unit and the first light splitting unit are arranged on the light emitting side of the light source; the first incident surface of the special-shaped prism is arranged in the reflection direction of the first reflection unit; the second reflection unit is arranged on the first light-emitting side of the first light splitting unit, the third reflection unit is arranged on the second light-emitting side of the first light splitting unit, and the second light splitting unit is arranged on the third light-emitting side of the first light splitting unit; the first surface of the holographic dry plate is arranged in the reflection direction of the second reflection unit and in the reflection direction of the third reflection unit; the second incident surface of the special-shaped prism is arranged on the first light-emitting side of the second light splitting unit, and the third incident surface of the special-shaped prism is arranged on the second light-emitting side of the second light splitting unit; the second surface of the holographic dry plate is arranged adjacent to the emergent surface of the special-shaped prism.

2. The production apparatus according to claim 1, wherein the light of the light source includes a first light and a first light beam which are parallel to each other;

the first reflection unit is also arranged in the propagation direction of the first light beam;

the first light splitting unit is also arranged in the propagation direction of the first light;

the first light beam is emitted to a first incident surface of the special-shaped prism through the first reflecting unit and is emitted to a second surface of the holographic dry plate through an emitting surface of the special-shaped prism; the first light is divided into a second light beam, a third light beam and a second light beam through the first light splitting unit; the second light beam is emitted to the second reflection unit through the first light emitting side of the first light splitting unit and is emitted to the first surface of the holographic dry plate through the second reflection unit; the third light beam is emitted to the third reflection unit through the second light emitting side of the first light splitting unit and is emitted to the first surface of the holographic dry plate through the third reflection unit; the second light is emitted to the second light splitting unit through the first light emitting side of the first light splitting unit and is split into a fourth light beam, a fifth light beam and a sixth light beam through the second light splitting unit; the fourth light beam is emitted to the second incident surface of the special-shaped prism through the first light-emitting side of the second light splitting unit and is emitted to the second surface of the holographic dry plate through the emitting surface of the special-shaped prism; the fifth light beam and the sixth light beam are both emitted to a third incident surface of the special-shaped prism through a second light-emitting side of the second light splitting unit and are emitted to a second surface of the holographic dry plate through an emitting surface of the special-shaped prism;

the holographic stem plate comprises a first area, a second area and a third area, and the holographic stem plate is used for forming a coupling-in grating in the first area by the first light beam and the second light beam in a coherent mode, forming a coupling-out grating in the second area by the third light beam and the fifth light beam in a coherent mode, and forming a turning grating in the third area by the fourth light beam and the sixth light beam in a coherent mode, so that a holographic optical waveguide is formed.

3. The production apparatus according to claim 1, wherein the first beam splitting unit includes a first beam splitter and a second beam splitter;

the light source is arranged on the light source, the light source is arranged on the light inlet side of the first spectroscope, the light inlet side of the second spectroscope is arranged on the first light outlet side of the first spectroscope, the second spectroscope is arranged on the second light outlet side of the first spectroscope, the second reflecting unit is arranged on the first light outlet side of the second spectroscope, and the third reflecting unit is arranged on the second light outlet side of the second spectroscope.

4. The production apparatus according to claim 3, wherein the second reflecting unit includes a first reflecting mirror;

the first reflector is arranged on a first light-emitting side of the first light splitting unit, and the first surface of the holographic dry plate is arranged in the reflection direction of the first reflector.

5. The production device according to claim 4, wherein the third reflecting unit includes a second reflecting mirror and a third reflecting mirror;

the second reflector is arranged on the second light-emitting side of the first light splitting unit, the third reflector is arranged in the reflecting direction of the second reflector, and the first surface of the holographic dry plate is arranged in the reflecting direction of the third reflector.

6. The production apparatus according to claim 5, wherein the first reflecting unit includes a fourth mirror and a fifth mirror;

the fourth reflector is arranged on the light emitting side of the light source, the fifth reflector is arranged in the reflecting direction of the fourth reflector, and the first incident surface of the special-shaped prism is arranged in the reflecting direction of the fifth reflector.

7. The production apparatus according to claim 6, wherein the second beam splitting unit includes a third beam splitter, a sixth mirror, and a seventh mirror;

the income light side of third beam splitter locates the third light-emitting side of first beam splitter unit, the second incident surface of dysmorphism prism is located the first light-emitting side of third beam splitter, the sixth speculum is located the second light-emitting side of third beam splitter, the seventh speculum is located on the direction of reflection of sixth speculum, the third incident surface of dysmorphism prism is located on the direction of reflection of seventh speculum.

8. The manufacturing apparatus according to claim 7, wherein the first mirror, the third mirror, the fifth mirror, the third beam splitter, and the seventh mirror are fixed to different slide table.

9. The manufacturing apparatus as set forth in claim 2 wherein said shaped prism further has a reflecting surface;

the special-shaped prism is used for receiving the fifth light beam and the sixth light beam through the third incident surface, reflecting the fifth light beam and the sixth light beam to the emergent surface through the reflecting surface, and enabling the fifth light beam and the sixth light beam to be emergent to the second surface of the holographic dry plate through the emergent surface.

10. The production device of any one of claims 1-9, wherein the light source comprises at least one laser and a beam combiner;

each laser is arranged at each input end of the beam combiner, and the first reflection unit and the first light splitting unit are arranged at the output end of the beam combiner.

11. The fabrication apparatus according to claim 10, further comprising a polarization splitting prism;

the incident end of the polarization beam splitter prism is arranged at the output end of the beam combiner, and the first reflection unit and the first beam splitter unit are arranged at the emergent end of the polarization beam splitter prism.

12. The production device according to claim 11, further comprising a spatial filter and a collimating unit;

the light-in side of the spatial filter is arranged at the emergent end of the polarization beam splitter prism, the light-out side of the spatial filter is arranged at the light-in side of the collimation unit, and the first reflection unit and the first beam splitter unit are arranged at the light-out side of the collimation unit.

13. A holographic optical waveguide obtained by the fabrication apparatus of any of claims 1 to 12, wherein the holographic optical waveguide is an angle-multiplexed and/or wavelength-multiplexed holographic optical waveguide.

14. The holographic optical waveguide according to claim 13, wherein the fringe period Λ 1 of the incoupling grating, the fringe period Λ 1 of the outcoupling grating, and the fringe period Λ 3 of the turning grating formed by exposure to light of the same wavelength satisfy the following relationship:

Λ1=Λ2；

Λ3=Λ1/(2cos(α/2));

15. The holographic optical waveguide of claim 14, wherein the diffraction efficiency of the turning grating gradually increases from a side facing the incoupling grating to a side facing away from the incoupling grating, and the diffraction efficiency of the outcoupling grating gradually increases from a side facing the turning grating to a side facing away from the turning grating.

16. A near-eye display device comprising at least one holographic optical waveguide according to any of claims 13 to 15.

17. A near-eye display device in accordance with claim 16 wherein the near-eye display device comprises a layer of holographic optical waveguide that is a wavelength-multiplexed and angle-multiplexed holographic optical waveguide.

18. The near-eye display device of claim 16, wherein the near-eye display device comprises M layers of holographic optical waveguides, wherein the M layers of holographic optical waveguides are all wavelength-multiplexed holographic optical waveguides, and the M layers of holographic optical waveguides respectively correspond to M groups of different exposure angles;

or the near-eye display device comprises N layers of holographic optical waveguides, wherein the N layers of holographic optical waveguides are angle multiplexing holographic optical waveguides, the N layers of holographic optical waveguides respectively correspond to N different exposure wavelengths,

wherein M is an integer greater than or equal to 2, and N is an integer greater than or equal to 2.