CN114089469B

CN114089469B - Volume holographic optical waveguide, manufacturing method thereof and color volume holographic optical waveguide

Info

Publication number: CN114089469B
Application number: CN202210066995.6A
Authority: CN
Inventors: 杨鑫; 罗润秋; 宋强; 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: 2022-05-06
Anticipated expiration: 2042-01-20
Also published as: CN114089469A

Abstract

The embodiment of the invention provides a volume holographic optical waveguide, a manufacturing method thereof and a color volume holographic optical waveguide, wherein the method comprises the following steps: providing a holographic dry plate, a prism and a flat glass; arranging a first side of the holographic dry plate on a first surface of the prism; arranging the second side of the holographic dry plate on the first surface of the flat glass; attaching the first surface of the prism, the holographic dry plate and the flat glass by using a refractive index matching fluid, or filling the first surface of the prism, the holographic dry plate and the flat glass by using the refractive index matching fluid; and carrying out one-time exposure on the holographic dry plate by a plurality of laser beams. The manufacturing method can make the manufactured coupling-in grating, coupling-out grating and turning grating all be reflective volume holographic gratings when the volume holographic optical waveguide is manufactured, and subsequently can avoid aliasing of various composite gratings in the required grating, and improve the field angle size and field brightness uniformity of the volume holographic optical waveguide.

Description

Volume holographic optical waveguide, manufacturing method thereof and color volume holographic optical waveguide

Technical Field

The embodiment of the invention relates to the technical field of optics, in particular to a volume holographic optical waveguide, a manufacturing method thereof and a color volume holographic optical waveguide.

Background

In an Augmented Reality (AR) near-eye display system based on a volume holographic optical waveguide, the larger the Field of view (FOV) of the volume holographic optical waveguide is, the larger the screen can be made larger, so that a user can obtain an immersive experience, and the viewing experience is improved. In addition, reducing the volume and weight of the optical system (light engine) is critical for AR display marketization applications.

In order to reduce the volume and weight of the optical machine, a two-dimensional pupil expansion volume holographic optical waveguide is generally adopted, the optical diffraction part of the optical waveguide consists of three grating areas including an in-coupling grating, a turning grating and an out-coupling grating, and the three gratings are all reflective volume holographic gratings to increase the field angle, so that the volume of the optical machine can be reduced and an eye box (eyebox) can be increased.

At present, a single prism coupling and single exposure mode can be adopted, and the coupled grating, the turning grating and the coupled grating can be obtained by exposure in three areas at the same time, so that the two-dimensional pupil expanding holographic optical waveguide is prepared. However, in this exposure method, the light totally reflected in different directions on the surface of the material also participates in the exposure of the required grating region, which results in that a plurality of complex grating structures are recorded in all three grating regions, and in addition, the turning grating can only be exposed as a transmission type volume holographic grating, and the smaller angular bandwidth of the turning grating will limit the angle of view of the finally viewed image, resulting in the smaller angle of view of the finally coupled light. In addition, in the multiple groups of composite gratings, the transmission type volume holographic grating and the reflection type volume holographic grating have different diffraction angle bandwidths for light rays in the optical waveguide, so that the coupled light rays are unevenly distributed in an eye box area, and the brightness uniformity of a picture observed by human eyes is reduced.

Disclosure of Invention

The embodiment of the invention mainly provides a volume holographic optical waveguide, a manufacturing method thereof and a chromatic volume holographic optical waveguide, wherein the method can ensure that an in-grating, an out-grating and a turning grating of the manufactured volume holographic optical waveguide are single reflection type volume holographic gratings when the volume holographic optical waveguide is manufactured, and the total reflection position of redundant light in a prism is changed by adding flat glass or manufacturing a glass cavity, so that the aliasing of various composite gratings in the required gratings is avoided, and the field angle and the field uniformity of the volume holographic optical waveguide are improved.

In a first aspect, an embodiment of the present invention provides a method for manufacturing a volume holographic optical waveguide, including:

providing a holographic dry plate, a prism and a flat glass;

arranging a first side of the holographic dry plate on a first surface of the prism;

arranging the second side of the holographic dry plate on the first surface of the flat glass;

attaching the first surface of the prism, the holographic dry plate and the flat glass by using a refractive index matching fluid, or filling the first surface of the prism, the holographic dry plate and the flat glass by using the refractive index matching fluid;

and carrying out one-time exposure on the holographic dry plate by a plurality of laser beams.

In some embodiments, said exposing said holographic dry plate by a plurality of lasers comprises:

providing a third light beam and a fourth light beam;

controlling the third light beam to be incident to the second surface of the prism, so that the third light beam is transmitted to the plate glass through the first surface of the prism and the holographic dry plate, is totally reflected by the plate glass, then is transmitted to the third surface of the prism through the holographic dry plate and the first surface of the prism, and is totally reflected to the second surface of the prism to be emitted out through the third surface of the prism;

controlling the fourth light beam to be incident on the fourth surface of the prism, so that the fourth light beam is transmitted to the plate glass through the first surface of the prism and the holographic dry plate, and is emitted through the holographic dry plate, the first surface of the prism and the fifth surface of the prism after being totally reflected by the plate glass; when the fourth light beam passes through the holographic dry plate for the first time, the fourth light beam and the third light beam reflected by the flat glass are coherent on a first area of the holographic dry plate to form a turning grating, and the area of the fourth light beam totally reflected to the holographic dry plate by the flat glass is not overlapped with the first area.

In some embodiments, said exposing said holographic dry plate by a plurality of lasers further comprises:

providing a first beam, a second beam, a fifth beam, and a sixth beam;

controlling the first light beam to be incident on the fifth surface of the prism, so that the first light beam is transmitted to the plate glass through the first surface of the prism and the holographic dry plate, and is emitted out through the holographic dry plate, the first surface of the prism and the fourth surface of the prism after being totally reflected by the plate glass;

controlling the second light beam to be incident to the second side of the holographic dry plate through the flat glass, so that the second light beam is emitted through the holographic dry plate, the first surface of the prism and the sixth surface of the prism; when the first light beam passes through the holographic dry plate for the first time, the first light beam and the second light beam are coherent to form an incoupling grating on a second area of the holographic dry plate, and the area of the first light beam which is totally reflected to the holographic dry plate through the flat glass is not overlapped with the second area;

controlling the sixth light beam to be incident to the second side of the holographic dry plate through the flat glass, so that the sixth light beam is emitted through the holographic dry plate, the first surface of the prism and the sixth surface of the prism;

controlling the fifth light beam to be incident to the second surface of the prism, so that the fifth light beam is transmitted to the plate glass through the first surface of the prism and the holographic dry plate, is totally reflected by the plate glass, then is transmitted to the third surface of the prism through the holographic dry plate and the first surface of the prism, and is reflected to the second surface of the prism through the third surface of the prism to be emitted; when the fifth light beam passes through the holographic dry plate for the first time, the fifth light beam and the sixth light beam are coherent to form a coupled-out grating on a third area of the holographic dry plate, and the area of the fifth light beam totally reflected to the holographic dry plate through the flat glass is not overlapped with the third area.

In some embodiments, the prisms comprise shaped prisms.

In some embodiments, the refractive index errors of the prism, the holographic dry plate, the flat glass, and the refractive index matching fluid are less than or equal to a first threshold value.

In some embodiments, the method of making further comprises:

and cutting the exposed holographic dry plate.

In a second aspect, an embodiment of the present invention further provides a volume holographic optical waveguide, which is manufactured by the manufacturing method according to any one of the first aspect.

In a third aspect, an embodiment of the present invention further provides a color volume holographic optical waveguide, including a first volume holographic optical waveguide, a second volume holographic optical waveguide, and a third volume holographic optical waveguide, which are sequentially stacked from bottom to top, where at least one of the first volume holographic optical waveguide, the second volume holographic optical waveguide, and the third volume holographic optical waveguide is the volume holographic optical waveguide according to the second aspect.

In a fourth aspect, an embodiment of the present invention further provides another method for manufacturing a volume holographic optical waveguide, including:

providing a holographic dry plate and a prism, wherein a cavity is arranged in the prism;

placing the holographic dry plate in the cavity;

filling the cavity with an index matching fluid;

providing a third light beam and a fourth light beam;

controlling the third light beam to be incident to the second surface of the prism, so that the third light beam penetrates through the holographic dry plate to the first surface of the prism, is totally reflected by the first surface of the prism, penetrates through the holographic dry plate to the third surface of the prism, and is reflected to the second surface of the prism to be emitted;

controlling the fourth light beam to be incident on the fourth surface of the prism, enabling the fourth light beam to penetrate through the holographic dry plate to the first surface of the prism, and after being totally reflected by the first surface of the prism, the fourth light beam penetrates through the holographic dry plate and the fifth surface of the prism to be emitted; when the fourth light beam passes through the holographic dry plate for the first time, the fourth light beam and the third light beam reflected by the first surface of the prism are coherent on the first area of the holographic dry plate to form a turning grating, and the area of the fourth light beam totally reflected to the holographic dry plate by the first surface of the prism is not overlapped with the first area.

In some embodiments, the exposing the holographic plate by the plurality of lasers is performed once. The method also comprises the following steps:

providing a first beam, a second beam, a fifth beam, and a sixth beam;

controlling the first light beam to be incident on the fifth surface of the prism, so that the first light beam is transmitted to the first surface of the prism through the holographic dry plate, is totally reflected by the first surface of the prism, and is emitted out through the holographic dry plate and the fourth surface of the prism;

controlling the second light beam to be incident on the first surface of the prism, so that the second light beam is emitted through the holographic dry plate and the sixth surface of the prism; when the first light beam passes through the holographic dry plate for the first time, the first light beam and the second light beam are coherent to form an incoupling grating on a second area of the holographic dry plate, and the area of the first light beam which is totally reflected to the holographic dry plate through the first surface of the prism is not overlapped with the second area;

controlling the sixth light beam to be incident on the first surface of the prism, and enabling the sixth light beam to be emitted through the holographic dry plate and the sixth surface of the prism;

controlling the fifth light beam to be incident to the second surface of the prism, so that the fifth light beam penetrates through the holographic dry plate to the first surface of the prism, is totally reflected by the first surface of the prism, penetrates through the holographic dry plate to the third surface of the prism, and is reflected to the second surface of the prism to be emitted; when the fifth light beam passes through the holographic dry plate for the first time, the fifth light beam and the sixth light beam are coherent to form a coupled-out grating on a third area of the holographic dry plate, and the area of the fifth light beam totally reflected to the holographic dry plate through the first surface of the prism is not overlapped with the third area.

In some embodiments, the prisms comprise shaped prisms.

In some embodiments, after the placing the holographic dry plate in the cavity, the method of making further comprises:

and fixing the holographic dry plate on one side close to the first surface of the prism.

In some embodiments, the refractive index errors of the prism, the holographic dry plate, and the refractive index matching fluid are less than or equal to a first threshold.

In some embodiments, the method of making further comprises:

and cutting the exposed holographic dry plate.

In a fifth aspect, an embodiment of the present invention further provides a volume holographic optical waveguide, which is manufactured by the manufacturing method according to any one of the fourth aspects.

In a sixth aspect, an embodiment of the present invention further provides a color volume holographic optical waveguide, including a first volume holographic optical waveguide, a second volume holographic optical waveguide, and a third volume holographic optical waveguide, which are sequentially stacked from bottom to top, where at least one of the first volume holographic optical waveguide, the second volume holographic optical waveguide, and the third volume holographic optical waveguide is the volume holographic optical waveguide in the fifth aspect.

The beneficial effects of the embodiment of the invention are as follows: in contrast to the prior art, embodiments of the present invention provide a volume holographic optical waveguide, a method for manufacturing the volume holographic optical waveguide, and a color volume holographic optical waveguide, where the method includes: providing a holographic dry plate, a prism and a flat glass; arranging a first side of the holographic dry plate on a first surface of the prism; arranging the second side of the holographic dry plate on the first surface of the flat glass; attaching the first surface of the prism, the holographic dry plate and the flat glass by using a refractive index matching fluid, or filling the first surface of the prism, the holographic dry plate and the flat glass by using the refractive index matching fluid; and carrying out one-time exposure on the holographic dry plate by a plurality of laser beams. According to the manufacturing method, when the two-dimensional pupil expanding body holographic optical waveguide is manufactured, the holographic dry plates are interfered with each other by the aid of the multiple beams of laser, the two-dimensional pupil expanding body holographic optical waveguide can be manufactured by one-time exposure, recorded grating areas and other reflected light are separated from each other on the holographic dry plates, aliasing does not occur, recording of a composite grating in a required grating area caused by total reflection of the multiple beams of laser is avoided, the required two-dimensional pupil expanding body holographic optical waveguide can be cut and separated in a follow-up geometric cutting mode, the two-dimensional pupil expanding body holographic optical waveguide with the three grating areas all of a single grating structure can be obtained, the three gratings are all reflection type volume holographic gratings, the manufacturing process of the two-dimensional pupil expanding body holographic optical waveguide is simplified, the field angle is increased, and the uniformity of the field brightness is improved.

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 diagram of an optical path at a holographic plate when the holographic plate is exposed according to an embodiment of the present invention;

FIG. 2 is a schematic flow chart of a method for fabricating a volume holographic optical waveguide according to an embodiment of the present invention;

FIG. 3 is a schematic view of a partial structure of an apparatus for fabricating a volume holographic optical waveguide according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a glass chamber according to an embodiment of the present invention;

FIG. 5 is a schematic partial view of an alternative apparatus for fabricating a volume holographic optical waveguide according to embodiments of the present invention;

FIG. 6 is a partial schematic flow chart of step S15 in FIG. 2;

FIG. 7 is a schematic illustration of the optical path at the configuration shown in FIG. 3;

FIG. 8 is another partial flowchart of step S15 in FIG. 2;

FIG. 9 is a schematic diagram of the distribution of a holographic grating formed on a holographic plate after exposure, development and bleaching according to an embodiment of the present invention;

FIG. 10 is a schematic structural diagram of a color volume holographic optical waveguide provided by an embodiment of the present invention;

FIG. 11 is a schematic flow chart diagram of another method for fabricating a volume holographic optical waveguide according to embodiments of the present invention;

FIG. 12 is a schematic partial view of an apparatus for fabricating a further volume holographic optical waveguide according to an embodiment of the present invention;

FIG. 13 is a partial schematic flow chart diagram of step S24 of FIG. 11;

FIG. 14 is a schematic illustration of the optical path at the configuration shown in FIG. 12;

fig. 15 is another partial flowchart of step S24 in fig. 11.

Reference numerals: k1, parallel light incident on the light guide substrate at a total reflection angle, K2, parallel light incident perpendicularly to the light guide substrate, total reflection light rays of K1', K1, reflection light rays of K2', K2 via the second face of the prism; 10. a prism 11, a special-shaped prism; 20. a holographic dry plate 21, an optical waveguide substrate 22, a holographic photosensitive layer; 30. a plate glass; 41. side wall glass; 50. a cavity in the profiled prism; l1, first beam, L2, second beam, L3, third beam, L4, fourth beam, L5, fifth beam, L6, sixth beam; s1, a turning grating formed by the interference of a third beam and a fourth beam, S1', an area exposed on the holographic dry plate when the third beam passes through the holographic dry plate for the first time, S1", an area exposed on the holographic dry plate when the fourth beam is reflected by the plate glass and passes through the holographic dry plate, an incoupling grating formed by the interference of S2, the first beam and the second beam, S2', an area exposed on the holographic dry plate when the first beam is totally reflected to the holographic dry plate by the plate glass, an outcoupled grating formed by the interference of S3, a fifth beam and a sixth beam, S3', an area exposed on the holographic dry plate when the fifth beam is totally reflected to the holographic dry plate by the plate glass, 110, a first holographic optical waveguide, 120, a second holographic optical waveguide, 130 and a third holographic optical waveguide.

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.

At present, when a two-dimensional pupil-expanding volume holographic optical waveguide is manufactured, a single prism coupling light beam and a single exposure mode can be adopted for exposure, however, in the volume holographic optical waveguide manufactured in the mode, an in-coupling grating, a turning grating and an out-coupling grating all comprise composite gratings with various structures, so that the turning grating can only be a transmission type volume holographic grating, the size of a field angle can be limited finally due to the narrow angular bandwidth of the transmission type volume holographic grating, and the formation of the composite gratings can also influence the uniformity of the brightness of the field of view.

In addition, in this exposure mode, for the multiple groups of gratings recorded in the same grating region, please refer to fig. 1, where K1 is parallel light incident on the optical waveguide substrate 21 at a total reflection angle, K2 is parallel light incident on the optical waveguide substrate 21 perpendicularly, it can be seen from the figure that the light ray K1 is totally reflected when reaching the interface between the optical waveguide substrate 21 and the holographic sensitive layer 22, and the total reflected light ray is K1'; when K2 reaches the second surface of the prism 10 after transmitting through the optical waveguide substrate 21, a portion of the light is reflected by the second surface of the prism 10 to the exposed area of the holographic plate 20, which is K2'.

It can be understood that the 4 groups of light beams interfere with each other in the exposure area of the holographic dry plate 20, which are respectively K1-K1', K1-K2, K1-K2', K1'-K2, K1' -K2', and K2-K2', where K1-K1 'represents that the light beam K1 and the light beam K1' interfere with each other, which results in that the exposure area of the holographic dry plate 20 records six groups of gratings formed by the interference of the six groups of light beams when exposed, and the six groups of gratings include reflective gratings and transmissive gratings, and because the angular bandwidth of the transmissive gratings is narrow, the problem of uneven brightness of the image displayed by the subsequently manufactured volume holographic optical waveguide occurs, which affects the display effect of the volume holographic optical waveguide.

In view of the above, embodiments of the present invention provide a volume holographic optical waveguide and a manufacturing method thereof, in which an in-grating, an out-grating, and a turning grating of a two-dimensional pupil-expanding volume holographic optical waveguide manufactured by the manufacturing method are all reflective volume holographic gratings that are in a single type, and a grating region recorded on a holographic dry plate and other regions of total reflection light are separated from each other on the holographic dry plate in a clamping manner of plate glass, so that crosstalk does not occur, thereby preventing a composite grating from being recorded, and a desired two-dimensional pupil-expanding volume holographic optical waveguide can be obtained in a geometric cutting manner, so that an angle of view and uniformity of a field of the volume holographic optical waveguide can be improved.

In a first aspect, an embodiment of the present invention provides a method for manufacturing a volume holographic optical waveguide, referring to fig. 2, the method includes the following steps S11 to S15.

Step S11: a holographic plate, a prism and a flat glass are provided.

Referring to fig. 1, a holographic dry plate 20 includes an optical waveguide substrate 21 and a holographic photosensitive layer 22 disposed (e.g., disposed by coating) on a surface of the optical waveguide substrate 21. Among them, the material of the optical waveguide substrate 21 may be transparent glass or resin; the holographic sensitive layer 22 can be a holographic sensitive emulsion layer made of photopolymer, silver salt, dichromated gelatin, photorefractive material, photo-anisotropic material, or any other sensitive 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). The prism 10 includes, but is not limited to, a triangular prism or a special-shaped prism, etc., the prism 10 can be used for coupling at least two light beams when manufacturing a volume holographic optical waveguide, and the special-shaped prism is selected as the prism 10 in the following description to describe the manufacturing method provided by the present invention, which is not limited in practical application. Flat glass is also known as white or clear glass.

Step S12: the first side of the holographic dry plate is disposed on the first face of the prism.

Step S13: and arranging the second side of the holographic dry plate on the first surface of the flat glass.

Step S14: the first surface of the prism, the holographic dry plate and the flat glass are attached through the refractive index matching fluid, or the first surface of the prism, the holographic dry plate and the flat glass are filled through the refractive index matching fluid.

Specifically, referring to fig. 1 and 3, a first side of the holographic dry plate 20 is attached to a first surface of the irregular prism 11 by the refractive index matching fluid, and a second side of the holographic dry plate 20 is attached to a first surface of the plate glass 30 by the refractive index matching fluid. It should be understood that the side on which optical waveguide substrate 21 is located is typically the first side of holographic dry plate 20, and the side on which holographic sensitive layer 22 is located is the second side of holographic dry plate 20.

Or, referring to fig. 4, a glass cavity is provided, the glass cavity is composed of three side wall glasses 41 and a flat glass 30, then, a vacant surface surrounded by the three side wall glasses 41 is attached to the first surface of the irregular prism 11, referring to fig. 4 and 5, the holographic dry plate 20 is disposed in the glass cavity, and then, a refractive index matching liquid is injected into the vacant surface (or glass cavity) surrounded by the two side wall glasses 41 and the flat glass 30, so that the second side of the holographic dry plate 20 is attached to the first surface of the flat glass 30. Further, in the attaching process, magnetic stripes may be attached to the first side of the holographic dry plate 20 and the second side of the flat glass 30, and the holographic dry plate 20 attached with the magnetic stripes is placed in the glass cavity; then, filling the glass cavity with refractive index matching fluid; finally, the magnetic stripe is attracted by a magnet at the second side of the plate glass 30, and finally the holographic plate 20 can be fixed to the first side of the plate glass 30.

Step S15: and carrying out one-time exposure on the holographic dry plate by a plurality of laser beams.

Specifically, the three regions of the holographic dry plate 20 may be simultaneously exposed in a one-time exposure manner, so as to simultaneously obtain the two-dimensional pupil-expanding holographic optical waveguide having the in-coupling grating, the turning grating and the out-coupling grating, or the three regions of the holographic dry plate 20 may be sequentially exposed in a three-time exposure manner, so as to sequentially obtain the in-coupling grating, the turning grating and the out-coupling grating on the holographic dry plate 20, and finally obtain the two-dimensional pupil-expanding holographic optical waveguide. In practical applications, the turning grating can be set according to actual needs, and the limitation in this embodiment is not required.

In the manufacturing method, the holographic dry plate 20 is clamped by the special-shaped prism 11 and the plate glass 30, or the holographic dry plate 20 is placed in a glass cavity and then exposed, on one hand, three areas of the holographic dry plate 20 can be simultaneously exposed by designing the trend of an optical path, so that the two-dimensional pupil-expanding holographic optical waveguide with the coupling-in grating, the turning grating and the coupling-out grating which are all reflection type volume holographic gratings can be manufactured; when the holographic main plate 20 is exposed by the multi-beam laser, the area where the light is totally reflected to the holographic main plate 20 by the plane glass 30 is separated from the areas of the required coupling-in grating, the turning grating and the coupling-out grating, so that the single-frequency grating formed by exposing the required grating to the required light beam can be ensured, and the single-frequency grating is a reflective type volume holographic grating, and when the prepared two-dimensional pupil expanding volume holographic optical waveguide is used for displaying, the size and the brightness uniformity of a view field are improved, thereby improving the display effect of the volume holographic optical waveguide.

Specifically, in some embodiments, referring to fig. 6, the step S15 may include the following steps S151 to S153.

Step S151: providing a third light beam and a fourth light beam.

Step S152: and controlling the third light beam to be incident on the second surface of the prism, so that the third light beam is transmitted to the plate glass through the first surface of the prism and the holographic dry plate, is totally reflected by the plate glass, then is transmitted to the third surface of the prism through the holographic dry plate and the first surface of the prism, and is totally reflected to the second surface of the prism to be emitted through the third surface of the prism.

Step S153: controlling the fourth light beam to be incident on the fourth surface of the prism, so that the fourth light beam is transmitted to the plate glass through the first surface of the prism and the holographic dry plate, and is emitted through the holographic dry plate, the first surface of the prism and the fifth surface of the prism after being totally reflected by the plate glass; when the fourth light beam passes through the holographic dry plate for the first time, the fourth light beam and the third light beam reflected by the flat glass are coherent on a first area of the holographic dry plate to form a turning grating, and the area of the fourth light beam totally reflected to the holographic dry plate by the flat glass is not overlapped with the first area.

It is understood that the third light beam L3 and the fourth light beam L4 are split by the same laser beam.

Specifically, referring to fig. 3 and 7, after the third light beam L3 enters the special-shaped prism 11 from the second surface of the special-shaped prism 11, it passes through the first surface of the special-shaped prism 11 and the holographic dry plate 20 and enters the flat glass 30, and is totally reflected on the flat glass 30; then, the third light beam L3 is totally reflected by the flat glass 30 to the second side of the holographic dry plate 20 and transmitted to the third surface of the special-shaped prism 11 through the holographic dry plate 20 and the first surface of the special-shaped prism 11; and finally, the light is totally reflected to the second surface of the special-shaped prism 11 through the third surface of the special-shaped prism 11 and is emitted.

Meanwhile, the fourth light beam L4 enters the special-shaped prism 11 from the fourth surface of the special-shaped prism 11, then directly exits from the first surface of the special-shaped prism 11 to the first side of the holographic dry plate 20, and passes through the holographic dry plate 20 to reach the plate glass 30; then, the light is totally reflected by the plate glass 30 and is emitted through the holographic plate 20, the first surface of the special-shaped prism 11, and the fifth surface of the special-shaped prism 11 again.

Thus, when the fourth light beam L4 passes through the holographic plate 20 for the first time, the fourth light beam L4 and the third light beam L3 reflected by the plate glass 30 are coherent to form a turning grating in the first region of the holographic plate 20, and the region where the fourth light beam L4 is totally reflected by the plate glass 30 to the holographic plate 20 and the first region where the turning grating is located are geometrically separated from each other, that is, there is no overlapping region. Through the way, when the two-dimensional pupil-expanding volume holographic optical waveguide is manufactured by adopting the single prism coupling exposure, the reflection type volume holographic grating can be formed on the first area of the holographic dry plate 20 by exposure, even if the turning grating of the manufactured volume holographic optical waveguide is the reflection type volume holographic grating; compared with the volume holographic optical waveguide with the turning grating being the transmission type volume holographic grating, the reflection type volume holographic grating generally has higher diffraction efficiency and larger angular bandwidth, so the volume holographic optical waveguide manufactured by the embodiment can improve the viewing angle when the volume holographic optical waveguide displays. In addition, through the above manner, only the third light beam L3 and the fourth light beam L4 are formed by once interference during the exposure of the turning grating, and the third light beam L3 and the fourth light beam L4 are emitted from the special-shaped prism 11 after the interference is completed, without participating in the exposure of the grating any more, so that the recording of the composite grating can be avoided, and the field angle size and the field brightness uniformity can be improved.

In some embodiments, referring to fig. 8, the step S15 may further include the following steps S154 to S158.

Step S154: providing a first light beam, a second light beam, a fifth light beam, and a sixth light beam.

Step S155: and controlling the first light beam to be incident on the fifth surface of the prism, so that the first light beam is transmitted to the plate glass through the first surface of the prism and the holographic dry plate, and is emitted out through the holographic dry plate, the first surface of the prism and the fourth surface of the prism after being totally reflected by the plate glass.

Step S156: controlling the second light beam to be incident to the second side of the holographic dry plate through the flat glass, so that the second light beam is emitted through the holographic dry plate, the first surface of the prism and the sixth surface of the prism; when the first light beam passes through the holographic dry plate for the first time, the first light beam and the second light beam are coherent to form a coupling-in grating on a second area of the holographic dry plate, and the area of the first light beam totally reflected to the holographic dry plate through the flat glass is not overlapped with the second area.

Step S157: and controlling the sixth light beam to be incident to the second side of the holographic dry plate through the flat glass, so that the sixth light beam is emitted through the holographic dry plate, the first surface of the prism and the sixth surface of the prism.

Step S158: controlling the fifth light beam to be incident to the second surface of the prism, so that the fifth light beam is transmitted to the plate glass through the first surface of the prism and the holographic dry plate, is totally reflected by the plate glass, then is transmitted to the third surface of the prism through the holographic dry plate and the first surface of the prism, and is reflected to the second surface of the prism through the third surface of the prism to be emitted; when the fifth light beam passes through the holographic dry plate for the first time, the fifth light beam and the sixth light beam are coherent to form a coupled-out grating on a third area of the holographic dry plate, and the area of the fifth light beam totally reflected to the holographic dry plate through the flat glass is not overlapped with the third area.

It is understood that the third light beam L3, the fourth light beam L4, the first light beam L1, the second light beam L2, the fifth light beam L5 and the sixth light beam L6 are split by the same laser.

Specifically, referring to fig. 3 and 7, the first light beam L1 enters the special-shaped prism 11 through the fifth surface of the special-shaped prism 11, then the first light beam L1 passes through the first surface of the special-shaped prism 11 and the holographic dry plate 20 to the flat glass 30, and finally is totally reflected by the flat glass 30 and then exits through the holographic dry plate 20, the first surface of the special-shaped prism 11 and the fourth surface of the special-shaped prism 11.

The second light beam L2 is incident on the holographic plate 20 through the plate glass 30, and exits through the holographic plate 20, the first surface of the special-shaped prism 11, and the sixth surface of the special-shaped prism 11.

The sixth light beam L6 is incident on the holographic plate 20 through the plate glass 30, and exits through the holographic plate 20, the first surface of the shaped prism 11, and the sixth surface of the shaped prism 11.

The fifth light beam L5 enters the special-shaped prism 11 through the second surface of the special-shaped prism 11, then the fifth light beam L5 passes through the first surface of the special-shaped prism 11 and the holographic dry plate 20 to reach the plate glass 30, finally is totally reflected by the plate glass 30, passes through the holographic dry plate 20 and the first surface of the special-shaped prism 11 to reach the third surface of the special-shaped prism 11, and finally is reflected by the third surface of the special-shaped prism 11 to exit to the second surface of the special-shaped prism 11.

When the first light beam L1 passes through the holographic plate 20 for the first time, the first light beam L1 and the second light beam L2 form an incoupling grating on the second area of the holographic plate 20 in a coherent manner, and the area where the first light beam L1 is totally reflected to the holographic plate 20 by the flat glass 30 and the second area where the incoupling grating is located are separated from each other in a geometric position, that is, there is no overlapping area; when the fifth light beam L5 passes through the holographic plate 20 for the first time, the fifth light beam L5 and the sixth light beam L6 are coherent to form a coupled grating on the third area of the holographic plate 20, and the area where the fifth light beam L5 is totally reflected to the holographic plate 20 by the plate glass 30 and the third area where the coupled grating is located are geometrically separated from each other, that is, there is no overlapping area.

In the above manner, after the exposure is completed, the holographic plate 20 can be converted into a two-dimensional pupil expansion holographic optical waveguide having an incoupling grating, an outcoupling grating and a turning grating. When the coupled grating is exposed, only the first light beam L1 and the second light beam L2 are formed by interference once, the first light beam L1 and the second light beam L2 are both emitted from the special-shaped prism 11 after the interference is completed, and do not participate in the exposure of the grating any more, meanwhile, when the coupled grating is exposed, only the fifth light beam L5 and the sixth light beam L6 are formed by interference once, and the fifth light beam L5 and the sixth light beam L6 are both emitted from the special-shaped prism 11 after the interference is completed, and do not participate in the exposure of the grating any more, so that the recording of the composite grating can be avoided, and the field angle size and the field brightness uniformity are improved.

The coupling grating is used for coupling image light with image information into the volume holographic optical waveguide and enabling the image light to be totally reflected and propagated towards the turning grating; the turning grating is used for receiving and diffracting the image light coupled in by the coupling-in grating, so that partial image light is turned to be totally reflected and transmitted towards the coupling-out grating, and the partial image light is continuously transmitted towards the original direction; the light-coupling grating is used for coupling the image light out of the volume holographic optical waveguide and finally transmitting the image light to human eyes.

Therefore, the manufacturing method can expose three areas on the holographic dry plate 20 at the same time, so that the holographic dry plate 20 has a grating structure of the three areas, and has the advantages of simple operation, high manufacturing efficiency, low cost and high yield. The prepared volume 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 an optical machine. In addition, the grating structure of the three regions is obtained by only two beams of light interference, and other composite gratings are not recorded, so that the field angle and the field brightness uniformity can be improved.

In order to ensure that the light passes through each medium without significant deflection, in some embodiments, the refractive index errors of the prism, holographic plate, flat glass, and index matching fluid are less than or equal to a first threshold. The first threshold may be 0, 2% or any other suitable error range, and may be set as needed in practical application, which is not limited herein.

In some of these embodiments, the method of making further comprises: and cutting the exposed holographic dry plate.

Specifically, taking a silver salt dry plate as an example, when the size of the holographic dry plate is large, the holographic dry plate exposed by the above method forms 7 grating regions on the holographic dry plate after development, bleaching, and other processes. Referring to fig. 7 and fig. 9, S1 is a turning grating formed by the interference of the third light beam L3 and the fourth light beam L4; s2 is a coupling-in grating formed by the interference of the first light beam L1 and the second light beam L2; s3 is a coupling-out grating formed by the interference of the fifth light beam L5 and the sixth light beam L6; s2' is an area exposed on the holographic plate when the first light beam L1 is totally reflected by the plate glass 30 to the holographic plate 20; s3' is an area exposed on the holographic plate when the fifth light beam L5 is totally reflected by the plate glass 30 to the holographic plate 20; s1' is the area exposed on the holographic plate 20 when the third light beam L3 first transmits the holographic plate 20; s1 ″ is an area exposed on the holographic plate 20 when the fourth light beam L4 passes through the holographic plate 20 after being reflected by the plate glass 30. It can be understood that the areas of S1, S1 'and S1 "are equal, the areas of S2 and S2' are equal, and the areas of S3 and S3 'are equal, and in order to ensure that the gratings are not interfered by each other by overlapping, the distances between their centers need to be kept consistent when the optical path is built, that is, the distance from the center of S1 to the center of S1', the distance from the center of S1 to the center of S1", the distance from the center of S2 to the center of S2', and the distance from the center of S3 to the center of S3' are equal; finally, as shown in fig. 9, the holographic dry plate is cut along the virtual image frame, and the complete two-dimensional pupil-expanding volume holographic optical waveguide can be obtained.

In a second aspect, an embodiment of the present invention further provides a volume holographic optical waveguide, which is manufactured by the manufacturing method according to any one of the above first aspects. The coupling-in grating, the coupling-out grating and the turning grating in the volume holographic optical waveguide are all reflection type holographic gratings, and the field angle and the field uniformity of the volume holographic optical waveguide during display can be improved.

In a third aspect, an embodiment of the present invention further provides a color volume holographic optical waveguide, including a first volume holographic optical waveguide, a second volume holographic optical waveguide, and a third volume holographic optical waveguide, which are sequentially stacked from bottom to top, where at least one of the first volume holographic optical waveguide, the second volume holographic optical waveguide, and the third volume holographic optical waveguide is the volume holographic optical waveguide according to the second aspect. At least one of the coupling-in grating, the coupling-out grating and the turning grating in the volume holographic optical waveguide in the color volume holographic optical waveguide is a reflection type holographic grating, so that the field angle and the field uniformity of the volume holographic optical waveguide during display can be improved.

For example, referring to fig. 10, in order to implement color display, the method for manufacturing a volume holographic waveguide according to the embodiment of the first aspect may be used, where a first volume holographic optical waveguide is manufactured by red laser exposure, a second volume holographic optical waveguide is manufactured by green laser exposure, and a third volume holographic optical waveguide is manufactured by blue laser exposure, and then the first volume holographic optical waveguide, the second volume holographic optical waveguide, and the third volume holographic optical waveguide are stacked to obtain a color volume holographic optical waveguide, where the color volume holographic optical waveguide is a color two-dimensional extended pupil volume holographic optical waveguide and can be used for color display. In practical applications, the laser with a suitable wavelength can be selected according to actual needs to be exposed to manufacture the volume holographic optical waveguide, and the limitation in this embodiment is not required.

In a fourth aspect, an embodiment of the present invention further provides a method for manufacturing a volume holographic optical waveguide, referring to fig. 11, the method includes the following steps S21 to S24.

Step S21: providing a holographic dry plate and a prism, wherein a cavity is arranged in the prism.

Step S22: placing the holographic dry plate in the cavity.

Step S23: the cavity is filled with an index matching fluid.

Step S24: and carrying out one-time exposure on the holographic dry plate by a plurality of laser beams.

The specific arrangement and function of the holographic dry plate and the prism are the same as those of the first embodiment of the present invention, and are not described herein again.

Unlike the first embodiment of the present invention, this embodiment provides a cavity in the prism, for example, a part of the special-shaped prism 11 can be hollowed out, as shown by the vertical stripe in fig. 12. Then, the holographic dry plate 20 is placed in the cavity 50, the cavity 50 is filled with refractive index matching fluid, and the second side of the holographic dry plate 20 is attached to one side, close to the first surface of the special-shaped prism 11, in the cavity 50; finally, the holographic plate 20 is exposed.

Through the above manner, on one hand, three areas of the holographic dry plate 20 can be exposed simultaneously by designing the direction of the optical path, so that the two-dimensional pupil expansion holographic optical waveguide with the coupling-in grating, the turning grating and the coupling-out grating all being reflective holographic gratings can be manufactured; when the holographic dry plate 20 is exposed by the multi-beam laser, the area where the multi-beam laser can be reflected back to the holographic dry plate 20 through the first surface of the special-shaped prism 11 and the area of the required coupling-in grating, turning grating and coupling-out grating are separated from each other, so that the required grating and other reflected lights can be prevented from being overlapped, the size of a view field and the uniformity of the brightness of the view field are improved when the manufactured two-dimensional pupil-expanding holographic optical waveguide is displayed, and the display effect of the volume holographic optical waveguide is improved.

In some embodiments, after the step S23, the manufacturing method may further include a step S231: and fixing the holographic dry plate on one side close to the first surface of the prism.

Illustratively, the holographic dry plate is secured to a side of the prism adjacent the first face with a magnetic strip; thus, the second side of the holographic dry plate is attached to one side of the cavity close to the first surface of the prism.

Specifically, with continued reference to fig. 12, after the magnetic stripes are attached to the first side of the holographic dry plate 20 and the first surface of the special-shaped prism 11, the holographic dry plate 20 attached with the magnetic stripes is placed in the cavity 50; then, the cavity 50 is filled with an index matching fluid; finally, the magnetic stripe is attracted by a magnet at the first face of the shaped prism 11, and finally the holographic plate 20 may be fixed in the cavity 50 at a side close to the first face of the shaped prism 11.

In order to ensure that the light passes through each medium without significant deflection, in some embodiments, the refractive index errors of the prism, holographic dry plate, and index matching fluid are less than or equal to a first threshold. The first threshold may be 0, 2% or any other suitable error range, and may be set as needed in practical application, which is not limited herein.

In some embodiments, referring to fig. 13, the step S24 includes the following steps S241 to S243.

Step S241: providing a third light beam and a fourth light beam.

Step S242: and controlling the third light beam to be incident to the second surface of the prism, so that the third light beam penetrates through the holographic dry plate to the first surface of the prism, is totally reflected by the first surface of the prism, penetrates through the holographic dry plate to the third surface of the prism, and is reflected to the second surface of the prism to be emitted through the third surface of the prism.

Step S243: controlling the fourth light beam to be incident on the fourth surface of the prism, enabling the fourth light beam to penetrate through the holographic dry plate to the first surface of the prism, and after being totally reflected by the first surface of the prism, the fourth light beam penetrates through the holographic dry plate and the fifth surface of the prism to be emitted; when the fourth light beam passes through the holographic dry plate for the first time, the fourth light beam and the third light beam reflected by the first surface of the prism are coherent on the first area of the holographic dry plate to form a turning grating, and the area of the fourth light beam totally reflected to the holographic dry plate by the first surface of the prism is not overlapped with the first area.

Specifically, referring to fig. 12 and 14, after the third light beam L3 enters the special-shaped prism 11 from the second surface of the special-shaped prism 11, it passes through the refractive index matching fluid in the cavity 50 and the holographic dry plate 20 to reach the first surface of the special-shaped prism 11; then, the third light beam L3 is totally reflected to the holographic dry plate 20 by the first surface of the special-shaped prism 11, and is transmitted to the third surface of the special-shaped prism 11 through the holographic dry plate 20 and the refractive index matching fluid in the cavity 50; and finally, the light is totally reflected to the second surface of the special-shaped prism 11 through the third surface of the special-shaped prism 11 and is emitted.

Meanwhile, the fourth light beam L4 enters the special-shaped prism 11 from the fourth surface of the special-shaped prism 11, and then passes through the refractive index matching fluid in the cavity 50 and the holographic dry plate 20 to reach the first surface of the special-shaped prism 11; then, the light is totally reflected by the first surface of the special-shaped prism 11 and is emitted through the holographic plate 20 and the fifth surface of the special-shaped prism 11.

Thus, in the first region of the holographic plate 20, the fourth light beam L4 and the third light beam L3 reflected by the first surface of the special-shaped prism 11 are coherent to form a turning grating, and the region where the fourth light beam L4 is totally reflected to the holographic plate 20 by the first surface of the special-shaped prism 11 and the first region where the turning grating is located are geometrically separated from each other, that is, there is no overlapping region. By adopting the mode, when the two-dimensional pupil expanding volume holographic optical waveguide is manufactured by adopting the coupling exposure of the single prism, the reflection type volume holographic grating can be formed on the first area of the holographic dry plate 20 by exposure, so that the turning grating of the manufactured volume holographic optical waveguide is the reflection type volume holographic grating; compared with the volume holographic optical waveguide with the turning grating being the transmission type volume holographic grating, the reflection type volume holographic grating generally has a larger angular bandwidth, so that the volume holographic optical waveguide manufactured by the embodiment can improve the viewing angle when the volume holographic optical waveguide displays. In addition, through the above manner, only the third light beam L3 and the fourth light beam L4 are formed by once interference during the exposure of the turning grating, and the third light beam L3 and the fourth light beam L4 are emitted from the special-shaped prism 11 after the interference is completed, without participating in the exposure of the grating any more, so that the recording of the composite grating can be avoided, and the field angle size and the field brightness uniformity can be improved.

In some embodiments, referring to fig. 15, the step S24 further includes the following steps S244 to S248.

Step S244: providing a first light beam, a second light beam, a fifth light beam, and a sixth light beam.

Step S245: and controlling the first light beam to be incident on a fifth surface of the prism, so that the first light beam is transmitted to the first surface of the prism through the holographic dry plate, is totally reflected by the first surface of the prism, and is emitted through the holographic dry plate and a fourth surface of the prism.

Step S246: controlling the second light beam to be incident on the first surface of the prism, and enabling the second light beam to be emitted through the holographic dry plate and the sixth surface of the prism; when the first light beam passes through the holographic dry plate for the first time, the first light beam and the second light beam are coherent to form an incoupling grating on a second area of the holographic dry plate, and the area from the first light beam to the holographic dry plate through total reflection of the first surface of the prism is not overlapped with the second area.

Step S247: and controlling the sixth light beam to be incident on the first surface of the prism, so that the sixth light beam is emitted through the holographic dry plate and the sixth surface of the prism.

Step S248: controlling the fifth light beam to be incident to the second surface of the prism, so that the fifth light beam penetrates through the holographic dry plate to the first surface of the prism, is totally reflected by the first surface of the prism, penetrates through the holographic dry plate to the third surface of the prism, and is reflected to the second surface of the prism to be emitted; when the fifth light beam passes through the holographic dry plate for the first time, the fifth light beam and the sixth light beam are coherent to form a coupled-out grating on a third area of the holographic dry plate, and the area of the fifth light beam totally reflected to the holographic dry plate through the first surface of the prism is not overlapped with the third area.

It is understood that the third light beam L1, the fourth light beam L2, the first light beam L3, the second light beam L4, the fifth light beam L5 and the sixth light beam L6 are split by the same laser.

Specifically, referring to fig. 12 and 14, the first light beam L1 enters the special-shaped prism 11 through the fifth surface of the special-shaped prism 11, then the first light beam L1 passes through the refractive index matching fluid in the cavity 50 and the holographic dry plate 20 to reach the first surface of the special-shaped prism 11, and finally is totally reflected by the first surface of the special-shaped prism 11 and then exits through the holographic dry plate 20, the refractive index matching fluid in the cavity 50 and the fourth surface of the special-shaped prism 11.

The second light beam L2 enters the holographic plate 20 through the first surface of the special-shaped prism 11, and exits through the holographic plate 20, the refractive index matching fluid in the cavity 50, and the sixth surface of the special-shaped prism 11.

The sixth light beam L6 enters the holographic plate 20 through the first surface of the special-shaped prism 11, and exits through the holographic plate 20, the refractive index matching fluid in the cavity 50, and the sixth surface of the special-shaped prism 11.

The fifth light beam L5 enters the special-shaped prism 11 through the second surface of the special-shaped prism 11, then the fifth light beam L5 passes through the refractive index matching fluid in the cavity 50 and the holographic dry plate 20 to reach the first surface of the special-shaped prism 11, then is totally reflected by the first surface of the special-shaped prism 11, passes through the holographic dry plate 20 and the refractive index matching fluid in the cavity 50 to reach the third surface of the special-shaped prism 11, and finally is reflected by the third surface of the special-shaped prism 11 to exit to the second surface of the special-shaped prism 11.

When the first light beam L1 passes through the holographic plate 20 for the first time, the first light beam L1 and the second light beam L2 are coherent to form an incoupling grating on the second area of the holographic plate 20, and the area where the first light beam L1 is totally reflected to the holographic plate 20 through the first surface of the special-shaped prism 11 and the second area where the incoupling grating is located are geometrically separated from each other, that is, there is no overlapping area; when the fifth light beam L5 passes through the holographic dry plate 20 for the first time, the fifth light beam L5 and the sixth light beam L6 form a coupled-out grating in the third area of the holographic dry plate 20, and the area where the fifth light beam L5 is totally reflected to the holographic dry plate 20 by the first surface of the special-shaped prism 11 and the third area where the coupled-out grating is located are separated from each other in geometric position, that is, there is no overlapping area.

Therefore, the manufacturing method can expose three areas on the holographic dry plate 20 at the same time, so that the holographic grating has a grating structure of the three areas, and has the advantages of simple operation, high manufacturing efficiency, low cost and high yield. And the prepared volume holographic optical waveguide is applied to near-eye display equipment, so that the volume of an optical machine can be reduced while the field angle and the eye movement range are remarkably improved. In addition, the grating structure of the three regions is obtained by only two beams of light interference, and other composite gratings are not recorded, so that the field angle and the field brightness uniformity can be improved.

In some of these embodiments, the method of making further comprises: and cutting the exposed holographic dry plate. This step is the same as that described in the embodiment of the first aspect of the present invention, and is not described herein again.

In a fifth aspect, an embodiment of the present invention further provides a volume holographic optical waveguide, which is manufactured by the manufacturing method according to any one of the fourth aspects. The coupling grating, the turning grating and the coupling grating in the volume holographic optical waveguide are all single reflection type holographic gratings, and the field angle and the field uniformity of the volume holographic optical waveguide during display can be improved.

In a sixth aspect, an embodiment of the present invention further provides a color volume holographic optical waveguide, including a first volume holographic optical waveguide, a second volume holographic optical waveguide, and a third volume holographic optical waveguide, which are sequentially stacked from bottom to top, where at least one of the first volume holographic optical waveguide, the second volume holographic optical waveguide, and the third volume holographic optical waveguide is the volume holographic optical waveguide in the fifth aspect. At least one of the coupling-in grating, the coupling-out grating and the turning grating in the volume holographic optical waveguide in the color volume holographic optical waveguide is a reflection type holographic grating, so that the field angle and the field uniformity of the volume holographic optical waveguide during display can be improved.

For example, referring to fig. 10, in order to implement color display, the method for manufacturing a volume holographic waveguide according to the fourth embodiment may be used, in which a first volume holographic optical waveguide is manufactured by red laser exposure, a second volume holographic optical waveguide is manufactured by green laser exposure, and a third volume holographic optical waveguide is manufactured by blue laser exposure, and then the first volume holographic optical waveguide, the second volume holographic optical waveguide, and the third volume holographic optical waveguide are stacked to obtain a color volume holographic optical waveguide, which is a color two-dimensional extended pupil volume holographic optical waveguide and can be used for color display. In practical applications, the laser with a suitable wavelength can be selected according to actual needs to be exposed to manufacture the volume holographic optical waveguide, and the limitation in this embodiment is not required.

To sum up, the embodiment of the present invention provides a volume holographic optical waveguide, a method for manufacturing the volume holographic optical waveguide, and a color volume holographic optical waveguide, wherein the method comprises: providing a holographic dry plate, a prism and a flat glass; arranging a first side of the holographic dry plate on a first surface of the prism; arranging the second side of the holographic dry plate on the first surface of the flat glass; attaching the first surface of the prism, the holographic dry plate and the flat glass by using a refractive index matching fluid, or filling the first surface of the prism, the holographic dry plate and the flat glass by using the refractive index matching fluid; and carrying out one-time exposure on the holographic dry plate by a plurality of laser beams. According to the manufacturing method, when the two-dimensional pupil expanding body holographic optical waveguide is manufactured, the holographic dry plates are interfered with each other by the aid of the multiple beams of laser, the two-dimensional pupil expanding body holographic optical waveguide can be manufactured by one-time exposure, recorded grating areas and other reflected light are separated from each other on the holographic dry plates, aliasing does not occur, recording of a composite grating in a required grating area caused by total reflection of the multiple beams of laser is avoided, the required two-dimensional pupil expanding body holographic optical waveguide can be cut and separated in a follow-up geometric cutting mode, the two-dimensional pupil expanding body holographic optical waveguide with the three grating areas all of a single grating structure can be obtained, the three gratings are all reflection type volume holographic gratings, the manufacturing process of the two-dimensional pupil expanding body holographic optical waveguide is simplified, the field angle is increased, and the uniformity of the field brightness is improved.

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, and 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 method of making a volume holographic optical waveguide, comprising:

providing a holographic dry plate, a prism and a flat glass;

exposing the holographic dry plate once by a plurality of laser beams,

during exposure, the total reflection position of the redundant light in the prism is changed through the flat glass, the redundant light is totally reflected to the area of the holographic dry plate and is mutually separated from the required grating area,

the redundant light is the light which is used for recording the composite grating in the needed grating area after participating in exposure of the needed grating area and is totally reflected by the flat glass;

wherein the prisms comprise profiled prisms.

2. The method of claim 1, wherein said exposing the holographic plate by multiple lasers comprises:

providing a third light beam and a fourth light beam;

controlling the fourth light beam to be incident on a fourth surface of the prism, so that the fourth light beam is transmitted to the plate glass through the first surface of the prism and the holographic dry plate, is totally reflected by the plate glass, and is emitted through the holographic dry plate, the first surface of the prism and a fifth surface of the prism; when the fourth light beam passes through the holographic dry plate for the first time, the fourth light beam and the third light beam reflected by the flat glass are coherent on a first area of the holographic dry plate to form a turning grating, and the area of the fourth light beam totally reflected to the holographic dry plate by the flat glass is not overlapped with the first area.

3. The method of claim 2, wherein the exposing the holographic plate by the plurality of lasers at one time further comprises:

providing a first beam, a second beam, a fifth beam, and a sixth beam;

4. The production method according to any one of claims 1 to 3, wherein the refractive index errors of the prism, the holographic dry plate, the plate glass, and the refractive index matching fluid are less than or equal to a first threshold value.

5. The method of manufacturing according to any one of claims 1-3, further comprising:

and cutting the exposed holographic dry plate.

6. A volume holographic optical waveguide, wherein said volume holographic optical waveguide is produced by the production method according to any of claims 1 to 5.

7. A chromatic volume holographic optical waveguide comprising a first volume holographic optical waveguide, a second volume holographic optical waveguide and a third volume holographic optical waveguide which are sequentially stacked from bottom to top, wherein at least one of the first volume holographic optical waveguide, the second volume holographic optical waveguide and the third volume holographic optical waveguide is the volume holographic optical waveguide of claim 6.

8. A method of making a volume holographic optical waveguide, comprising:

placing the holographic dry plate in the cavity;

filling the cavity with an index matching fluid;

exposing the holographic dry plate once by a plurality of laser beams,

during exposure, the total reflection position of the redundant light in the prism is changed through the first surface of the prism, so that the area of the holographic dry plate totally reflected by the redundant light is mutually separated from the required grating area,

the redundant light is the light which is reflected by the first surface of the prism after participating in exposure of the needed grating area and can cause the recording of the composite grating in the needed grating area;

wherein the prisms comprise profiled prisms.

9. The method of claim 8, wherein said exposing the holographic plate by multiple lasers comprises:

providing a third light beam and a fourth light beam;

10. The method of claim 9, wherein the exposing the holographic plate by the plurality of lasers at a time further comprises:

providing a first beam, a second beam, a fifth beam, and a sixth beam;

controlling the second light beam to be incident on the first surface of the prism, and enabling the second light beam to be emitted through the holographic dry plate and the sixth surface of the prism; when the first light beam passes through the holographic dry plate for the first time, the first light beam and the second light beam are coherent to form an incoupling grating on a second area of the holographic dry plate, and the area of the first light beam which is totally reflected to the holographic dry plate through the first surface of the prism is not overlapped with the second area;

controlling the fifth light beam to be incident to the second surface of the prism, so that the fifth light beam penetrates through the holographic dry plate to reach the first surface of the prism, is totally reflected by the first surface of the prism, penetrates through the holographic dry plate to reach the third surface of the prism, and is reflected to the second surface of the prism to be emitted; when the fifth light beam passes through the holographic dry plate for the first time, the fifth light beam and the sixth light beam are coherent to form a coupled-out grating on a third area of the holographic dry plate, and the area of the fifth light beam totally reflected to the holographic dry plate through the first surface of the prism is not overlapped with the third area.

11. The method of any of claims 8-10, wherein after placing the holographic dry plate in the cavity, the method further comprises:

12. The method of claim 11, wherein the refractive index errors of the prism, the holographic dry plate, and the refractive index matching fluid are less than or equal to a first threshold value.

13. The method of manufacturing according to any one of claims 8-10, further comprising:

and cutting the exposed holographic dry plate.

14. A volume holographic optical waveguide, produced by the production method according to any of claims 8 to 13.

15. A chromatic volume holographic optical waveguide comprising a first volume holographic optical waveguide, a second volume holographic optical waveguide and a third volume holographic optical waveguide which are sequentially stacked from bottom to top, wherein at least one of the first volume holographic optical waveguide, the second volume holographic optical waveguide and the third volume holographic optical waveguide is the volume holographic optical waveguide of claim 14.