CN114415276A

CN114415276A - Exposure apparatus and near-to-eye display apparatus

Info

Publication number: CN114415276A
Application number: CN202011172227.6A
Authority: CN
Inventors: 江丽; 于超; 蔡宏; 毛慧; 浦世亮
Original assignee: Hangzhou Hikvision Digital Technology Co Ltd
Current assignee: Hangzhou Hikvision Digital Technology Co Ltd
Priority date: 2020-10-28
Filing date: 2020-10-28
Publication date: 2022-04-29
Anticipated expiration: 2040-10-28
Also published as: CN114415276B

Abstract

The embodiment of the application discloses exposure equipment and near-to-eye display equipment, and belongs to the technical field of optics. The exposure apparatus includes: the device comprises a laser, a light beam conversion assembly, a liquid crystal spatial light modulator, a beam splitting assembly, a first reflecting assembly, a second reflecting assembly and a coupling assembly; the laser is used for emitting light beams; the light beam conversion assembly is positioned on the light inlet side of the liquid crystal spatial light modulator or the light outlet side of the beam splitting assembly; the liquid crystal spatial light modulator is positioned on the light incident side of the beam splitting assembly and is used for modulating the wave front phase distribution of the incident light beam so that the emergent light beam has phase difference in two different directions; the first reflection assembly is positioned on the first light-emitting side of the beam splitting assembly, and the second reflection assembly is positioned on the second light-emitting side of the beam splitting assembly; the coupling assembly is used for bearing the holographic diffraction substrate coated with the photopolymer material, and the light beams emitted by the first reflection assembly and the second reflection assembly can form a two-dimensional holographic diffraction grating on the holographic diffraction substrate coated with the photopolymer material.

Description

Exposure apparatus and near-to-eye display apparatus

Technical Field

The embodiment of the application relates to the technical field of optics, in particular to exposure equipment and near-to-eye display equipment.

Background

The development of modern projection display technology has promoted the emergence of near-to-eye display devices. A near-eye display device generally includes a projection assembly and a display assembly. The projection assembly is used for projecting an image onto the display assembly in a light beam mode, and the display assembly is used for presenting a virtual image in the observation range of a user according to the light beam projected by the projection assembly. At present, a display component includes an optical waveguide lens, and a one-dimensional first diffraction grating and a one-dimensional second diffraction grating which are disposed on the optical waveguide lens, where the first diffraction grating is used to couple a light beam projected by a projection component into the optical waveguide lens, and the light beam is totally reflected in the optical waveguide lens, and then is diffracted for multiple times in the same direction by the second diffraction grating and then coupled out of the optical waveguide lens.

Because the second diffraction grating can only perform multiple diffraction in the same direction (transverse or longitudinal), the size of the projection assembly can be set to be smaller in the direction, but the size of the projection assembly is larger in the other direction in which multiple diffraction cannot be performed, the design difficulty of the projection assembly is high, and the cost is high. Therefore, in order to reduce the size of the projection module and further increase the viewing angle, the light beam generally needs to be diffracted by the display module multiple times in two directions, that is, the second diffraction grating should be a two-dimensional diffraction grating.

In the related art, the second diffraction grating is a two-dimensional surface relief grating, and the light beam can be diffracted many times in two directions. The two-dimensional surface relief grating is prepared by adopting a nano-imprinting process. The nanoimprint process is divided into three processes: preparing for stamping, stamping and demoulding. Firstly, preparing an imprinting template, coating imprinting glue or other polymers on a substrate, then pressing the imprinting template on the imprinting glue under the action of mechanical external force, and curing the imprinting glue after heating or ultraviolet exposure to form a pattern (a light and dark stripe pattern) after the grooves and gaps of the imprinting template are fully filled by the imprinting glue. And finally, removing the mechanical external force and the imprinting template to finish the transfer of the pattern from the imprinting template to the imprinting glue. In addition, the polymer coated on the surface of the substrate can also be used as a functional structure, and a pattern is transferred from the adhesive layer to the substrate by combining a method such as reactive ion etching.

The nano-imprinting process is complex in process because an imprinting template needs to be prepared in advance in the process of preparing the two-dimensional diffraction grating, and when the two-dimensional surface relief grating with different diffraction efficiencies needs to be prepared, different imprinting templates need to be prepared in advance, and then imprinting and demolding are carried out. Meanwhile, precise equipment is needed to accurately control parameters such as pressure and temperature in the preparation process, and the preparation process is limited by expensive equipment, so that the preparation process is high in processing difficulty, low in volume production and high in production cost, and is not suitable for large-scale preparation of optical modules.

Disclosure of Invention

The embodiment of the application provides exposure equipment and near-to-eye display equipment, and can solve the problems of complex preparation process, high processing difficulty, low volume production, high production cost and the like of a two-dimensional surface relief grating in the related technology. The technical scheme is as follows:

in a first aspect, there is provided an exposure apparatus including: the device comprises a laser, a light beam conversion assembly, a liquid crystal spatial light modulator, a beam splitting assembly, a first reflecting assembly, a second reflecting assembly and a coupling assembly made of a photopolymer material;

the laser is used for emitting light beams, the liquid crystal spatial light modulator is located on the light-in side of the beam splitting assembly, the light beam conversion assembly is located on the light-in side of the liquid crystal spatial light modulator or the light-out side of the beam splitting assembly, the liquid crystal spatial light modulator is used for modulating the wave front phase distribution of the incident light beams, so that phase differences exist between the light beams emitted by the liquid crystal spatial light modulator in two different directions, and the light beam conversion assembly is used for converting the polarization direction of the incident light beams;

the first reflection subassembly is located the first light-emitting side of beam splitting subassembly, the second reflection subassembly is located the second light-emitting side of beam splitting subassembly, the coupling subassembly is located the light-emitting side of first reflection subassembly with the overlap region of the light-emitting side of second reflection subassembly, the coupling subassembly is used for bearing the holographic diffraction base plate that has the photopolymer material of coating, just the first reflection subassembly with the emergent light beam of second reflection subassembly is being coated with can form the holographic diffraction grating of two-dimentional on the holographic diffraction base plate of photopolymer material.

Optionally, the beam conversion assembly comprises a first half-wave plate and a polarizing beam splitter, and the beam splitting assembly comprises a beam splitter;

the first half wave plate is positioned at the light-emitting side of the laser and used for receiving light beams emitted by the laser and converting the light beams into S polarized light;

the polarization beam splitter is positioned on the light-emitting side of the first half-wave plate and between the liquid crystal spatial light modulator and the beam splitter, the first light-emitting side of the polarization beam splitter faces the liquid crystal spatial light modulator and faces away from the beam splitter, and the liquid crystal spatial light modulator is a reflective-type spatial light modulator and is used for modulating wave front phase distribution of the S polarized light so as to enable the S polarized light to have phase difference in two different directions and convert the S polarized light into P polarized light;

the first light-emitting side of the polarization beam splitter is the light-emitting side of the S-polarized light reflected by the polarization beam splitter.

the first half-wave plate is positioned on the light emitting side of the laser, and is used for receiving the light beam emitted by the laser and converting the light beam into S polarized light;

the polarization beam splitter is positioned on the light-emitting side of the first half-wave plate, the liquid crystal spatial light modulator is positioned on the first light-emitting side of the polarization beam splitter, the beam splitter is positioned on the light-emitting side of the liquid crystal spatial light modulator, and the liquid crystal spatial light modulator is a spatial light modulator with a transmission structure and is used for modulating the wave front phase distribution of the S polarized light so that the S polarized light has phase differences in two different directions and is converted into P polarized light;

the first half wave plate is positioned on the light emitting side of the laser, and is used for receiving the light beam emitted by the laser and converting the light beam into P polarized light;

the polarization beam splitter is positioned on the light-emitting side of the first half-wave plate, the liquid crystal spatial light modulator is positioned on the second light-emitting side of the polarization beam splitter, the beam splitter is positioned on the light-emitting side of the liquid crystal spatial light modulator, and the liquid crystal spatial light modulator is a spatial light modulator with a transmission structure and is used for modulating the wave front phase distribution of the P polarized light, so that the P polarized light has phase differences in two different directions and is converted into S polarized light;

and the second light-emitting side of the polarization beam splitter is the light-emitting side of the P-polarized light transmitted by the polarization beam splitter.

Optionally, the beam splitting assembly comprises a polarizing beam splitter, and the beam conversion assembly comprises a second half-wave plate;

the polarization beam splitter is positioned on the light outgoing side of the liquid crystal spatial light modulator, the liquid crystal spatial light modulator is a spatial light modulator with a transmission structure, the liquid crystal spatial light modulator is used for receiving light beams emitted by the laser and modulating the wave front phase distribution of the light beams so that the light beams have phase differences in two different directions, and the polarization beam splitter is used for dividing the light beams after phase distribution modulation into P polarized light and S polarized light, transmitting the P polarized light and reflecting the S polarized light;

the second half-wave plate is located between the polarization beam splitter and the first reflection assembly, the first light outlet side of the polarization beam splitter faces the second half-wave plate, and the second half-wave plate is used for converting S polarized light reflected by the polarization beam splitter into P polarized light.

the second half-wave plate is located between the polarization beam splitter and the second reflection assembly, the second light outlet side of the polarization beam splitter faces the second half-wave plate, and the second half-wave plate is used for converting the P polarized light transmitted by the polarization beam splitter into S polarized light.

Optionally, the exposure apparatus further comprises a third half-wave plate;

the third half-wave plate is located between the laser and the liquid crystal spatial light modulator, the third half-wave plate is used for receiving the light beam emitted by the laser, and the liquid crystal spatial light modulator is used for receiving the light beam emitted by the third half-wave plate.

Optionally, the first reflection assembly includes a first reflector, a first turntable, and a first slide rail;

the first reflector is fixed on the first rotary table, the first rotary table is located on the first slide rail and can slide along the first slide rail, and the length direction of the first slide rail is parallel to the direction of incident light of the first reflector.

Optionally, the second reflective assembly comprises a second reflector, a second turntable and a second slide rail;

the second reflector is fixed on the second turntable, the second turntable is located on the second sliding rail and can slide along the second sliding rail, and the length direction of the second sliding rail is parallel to the direction of incident light of the second reflector.

Optionally, the coupling assembly comprises a triangular prism and a trapezoidal prism;

the first side surface of the triangular prism faces the first reflection assembly, the second side surface of the triangular prism is in contact with the first surface of the holographic diffraction substrate, an included angle between the first side surface and the second side surface of the triangular prism is an acute angle, and the first surface of the holographic diffraction substrate is coated with the photopolymer material;

the lower bottom surface of the trapezoidal prism is in contact with the second surface of the holographic diffraction substrate.

Optionally, the exposure apparatus further comprises a collimated beam expanding assembly;

the collimation and beam expansion assembly is located on the light emitting side of the laser, and the collimation and beam expansion assembly is used for converting light beams emitted by the laser into parallel light and increasing the width of the parallel light.

Optionally, the collimated beam expanding assembly comprises a collimating lens and an objective lens;

the collimating lens is located the light-emitting side of laser instrument, objective is located collimating lens's light-emitting side, collimating lens is used for with the light beam of laser instrument outgoing converts the parallel light into, objective is used for increasing the width of parallel light.

Optionally, the exposure apparatus further comprises a third mirror;

the third reflector is located the light-emitting side of laser instrument and is located the income light side of collimation beam expanding subassembly, the third reflector is used for with the light beam reflection of laser instrument outgoing extremely collimation beam expanding subassembly.

In a second aspect, there is provided a near-eye display apparatus including a two-dimensional holographic diffraction grating formed by the exposure apparatus of any one of the first aspects.

The beneficial effects brought by the technical scheme provided by the embodiment of the application at least comprise:

in the embodiment of the application, the wave front phase distribution of the incident light beams is modulated through the liquid crystal spatial light modulator, so that the phase difference exists between the emergent light beams in two different directions, and then the interference exposure is carried out on the two light beams with the phase difference in the two different directions in the photopolymer material, so that the two-dimensional holographic diffraction grating can be formed. That is, the embodiment of the application utilizes the liquid crystal spatial light modulator to modulate the wavefront for generating the two-dimensional holographic diffraction grating, and then uses the modulated light beam to perform holographic interference exposure on the holographic diffraction substrate coated with the photopolymer material to form the two-dimensional holographic diffraction grating, so that the manufacturing difficulty and cost of the two-dimensional holographic diffraction grating are reduced, and the preparation yield of the two-dimensional holographic diffraction grating is improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a near-eye display device provided in an embodiment of the present application;

fig. 2 is a schematic structural diagram of a display module according to an embodiment of the present disclosure;

FIG. 3 is a schematic top view of a display assembly according to an embodiment of the present disclosure;

fig. 4 is a schematic diagram illustrating a relationship between an eye movement range size and a diffraction grating size without exit pupil expansion according to an embodiment of the present application;

fig. 5 is a diagram illustrating a relationship between an eye movement range size and a diffraction grating size with exit pupil expansion according to an embodiment of the present application;

FIG. 6 is a schematic top view of another display assembly provided by embodiments of the present application;

FIG. 7 is a schematic diagram of a wave-vector superposition provided by an embodiment of the present application;

FIG. 8 is a schematic top view of yet another display assembly provided by an embodiment of the present application;

FIG. 9 is a schematic diagram of another wave-vector superposition provided by an embodiment of the present application;

fig. 10 is a schematic structural diagram of a first exposure apparatus provided in an embodiment of the present application;

fig. 11 is a schematic structural diagram of a second exposure apparatus provided in an embodiment of the present application;

fig. 12 is a schematic structural diagram of a third exposure apparatus provided in an embodiment of the present application;

fig. 13 is a schematic structural diagram of a fourth exposure apparatus provided in an embodiment of the present application;

fig. 14 is a schematic structural diagram of a fifth exposure apparatus provided in an embodiment of the present application;

fig. 15 is a schematic structural diagram of a sixth exposure apparatus provided in an embodiment of the present application;

fig. 16 is a schematic structural diagram of a seventh exposure apparatus provided in an embodiment of the present application;

fig. 17 is a schematic structural diagram of an eighth exposure apparatus provided in an embodiment of the present application;

fig. 18 is a schematic structural diagram of a ninth exposure apparatus provided in an embodiment of the present application.

Reference numerals:

01: laser, 02: beam conversion assembly, 03: liquid crystal spatial light modulator, 04: beam splitting assembly, 05: first reflection assembly, 06: second reflective component, 07: coupling assembly, 08: holographic diffraction substrate, 09: third half-wave plate, 10: collimated beam expanding assembly, 11: a third reflector;

021: first half wave plate, 022: polarizing beam splitter, 023: second half-wave plate, 041: beam splitter, 042: polarizing beam splitter, 051: first mirror, 052: first carousel, 053: first slide rail, 061: second mirror, 062: second rotary table, 063: second slide rail, 071: triangular prism, 072: trapezoidal prism, 101: collimating lens, 102: an objective lens;

0221: first light exit side of polarizing beam splitter (022), 0222: second light exit side of polarizing beam splitter (022), 0421: first light exit side of polarizing beam splitter (042), 0422: second light exit side of polarizing beam splitter (042), 0711: first side of triangular prism, 0712: the second side of the triangular prism, the lower bottom of the 0721 trapezoidal prism.

Detailed Description

To make the objects, technical solutions and advantages of the embodiments of the present application more clear, the embodiments of the present application will be further described in detail with reference to the accompanying drawings.

Before explaining the embodiments of the present application in detail, relevant terms and application scenarios related to the embodiments of the present application will be described.

FOV (Field of view): refers to the range of angles of the image that the user can observe.

Eye movement range: refers to the movable range of the pupil. It is also understood that when the eye is moved to any position within the range, a clear image can be seen, but beyond the range, problems such as image distortion, color errors, and even no content may be displayed may occur.

As one example, the range of eye movement is at least as large as the pupil of the human eye, on the order of about 4 mm. Especially in a near-eye display device, the human eye needs to view a display image by moving on the optical waveguide lens, and therefore the size of the eye movement range is extended by at least several millimeters in each direction.

Exit pupil distance: the distance from the last surface of the optical waveguide lens to the exit pupil position.

Exit pupil expansion: one light beam is incident into the optical waveguide lens through the first diffraction grating, is totally reflected in the optical waveguide lens, and is coupled out of a plurality of light beams on the second diffraction grating, which is called exit pupil expansion.

Next, an application scenario of the embodiment of the present application will be explained.

With the development of optical technology, projection display technology is mature more and more, and the appearance of near-eye display devices is promoted. The near-eye display device may present a virtual image within the user's field of view. Fig. 1 is a schematic structural diagram of a near-eye display device provided in an embodiment of the present application, and as shown in fig. 1, the near-eye display device includes a projection assembly 101 and a display assembly 102.

The projection module 101 is configured to project an image to the Display module 102 in a form of a Light beam, and the projection module 101 may project the acquired image onto the Display module 102 through technologies such as LCOS (Liquid Crystal on Silicon), LCD (Liquid Crystal Display), DLP (Digital Light Processing), and OLED (Organic Light-Emitting Diode).

The display component 102 is used for presenting a virtual image in the observation range of the user according to the light beam projected by the projection component 101. Specifically, the display component 102 can diffract the light beam projected by the projection component 101 to the observation point through the diffraction grating, so that the receiving component can receive the image, wherein the receiving component can be a human eye or a detector, and the receiving component is not particularly limited in this embodiment.

Based on the near-eye display device shown in fig. 1, part of the user's requirements for the near-eye display device are mainly reflected in product performance (mainly including parameters such as field angle, eye movement range, field uniformity, exit pupil distance, and the like) and product appearance (light and comfortable, and the shape of the product is close to that of common myopic glasses). At present, the near-to-eye display equipment based on the optical waveguide lens has great progress and breakthrough in the aspect of product performance, and can basically meet the requirements. However, in terms of appearance, it is still difficult to meet the requirements of portability, small volume and shape close to that of common myopia glasses.

In the related art, the diffraction gratings in the display module 102 are all one-dimensional holographic diffraction gratings, and the light beam can only be expanded in one direction through the exit pupil, so that the size of the projection module 101 (e.g., a projection light machine) is larger in the direction without the exit pupil expansion, which increases the design difficulty of the projection module 101 and increases the cost. Moreover, in order to make the near-eye display device closer in appearance to the form of the myopic glasses, the size of the projection assembly 101 cannot be too large, and under this limitation, the field angle in the non-exit pupil expansion direction is small.

Therefore, in order to increase the field angle while reducing the size of the projection module 101, a two-dimensional exit pupil expansion technique is required to allow the incident beam to be diffracted multiple times in two directions, so as to realize exit pupil expansion in two directions. Typically, to achieve two-dimensional exit pupil expansion, the grating employed in the display assembly 102 is a two-dimensional surface relief grating, which can perform exit pupil expansion in two directions on the projection beam. The two-dimensional surface relief grating is prepared by adopting a nano-imprinting process, and an imprinting template needs to be prepared in advance in the process of preparing the two-dimensional diffraction grating by adopting the nano-imprinting process, namely, different imprinting templates need to be prepared in advance when the two-dimensional diffraction grating with different diffraction efficiencies is prepared, and then imprinting and demolding are carried out, so that the process is complex. Meanwhile, precise equipment is needed to accurately control parameters such as pressure and temperature in the preparation process, and the preparation process is limited by expensive equipment, so that the preparation process is high in processing difficulty, low in volume production and high in production cost, and is not suitable for large-scale preparation of optical modules.

Based on the above problem, the embodiment of the application provides an exposure apparatus, through which a two-dimensional diffraction grating can be prepared, and the manufacturing difficulty is low, the production cost is low, and the yield is high, and when the two-dimensional diffraction grating is applied to the display component 102, the design size of the projection component 101 in the near-to-eye display apparatus can be greatly reduced, and because there is no limitation on the size 101 of the projection component, the field angle of the display image can be increased to a certain extent.

For ease of understanding, the reason why the one-dimensional diffraction grating provided in the related art causes a projection element to be large in size, and how to reduce the size of the projection element will be explained next.

Fig. 2 is a schematic structural diagram of a display module 102, and referring to fig. 2, the display module 102 includes a first diffraction grating 1021, a second diffraction grating 1022, and an optical waveguide lens 1023. The projection assembly 101 projects a light beam (e.g., λ) of a spectral range₁-λ_nSpectral range of the light beam) to the display module 102, the first diffraction grating 1021 of the display module 102 couples the light beam projected by the projection module 101 into the optical waveguide lens 1023, and ensures the light beam to be totally reflected and propagated in the optical waveguide lens 1023, and then the light beam is coupled out of the optical waveguide lens by the second diffraction grating 1022And a sheet 1023.

Fig. 3 is a schematic top view of a display module 102 according to an embodiment of the present disclosure, and as seen from the top view, the first diffraction grating 1021 and the second diffraction grating 1022 are both one-dimensional diffraction gratings, and there is a periodic grating structure only in a horizontal direction (Y direction) in a plane where the second diffraction grating 1022 is located, and there is no periodic grating structure in a vertical direction (X direction) in the plane where the second diffraction grating 1022 is located.

It should be noted that the horizontal direction and the vertical direction are only two different directions in the plane of the second diffraction grating 1022, and the horizontal direction and the vertical direction may be two directions perpendicular to each other or two directions not perpendicular to each other, which is not limited in this embodiment of the application.

In order to eliminate the dispersion effect caused by the grating, the first diffraction grating 1021 and the second diffraction grating 1022 are structurally mirror-symmetric. That is, the grating period of the first diffraction grating 1021 is Λ₁Angle of inclination xi₁(ii) a The second diffraction grating 1022 has a period of Λ₂The angle of inclination is-xi₁。

As an example, the first diffraction grating 1021 and the second diffraction grating 1022 each adopt a holographic grating structure, and the diffraction efficiency thereof is determined by the refractive index modulation degree and the thickness of the holographic material.

For the first diffraction grating 1021, the tilt angle ξ₁Grating period Λ₁Are known values, and each wavelength in the spectral range corresponds to an angle of incidence that satisfies the bragg condition. Thus, λ₁-λ_nThe spectral range of (a) corresponds to an incident angle range [ theta ] satisfying the Bragg condition₁，θ_n]The light beam in the angle range can be diffracted by the first diffraction grating 1021, totally reflected by the optical waveguide lens 1023, propagated to the surface of the second diffraction grating 1022, diffracted by the second diffraction grating 1022, and emitted, and the viewing angle observed by the receiving assembly is | θ |_n-θ₁|。

As an example, as shown in FIG. 2, the projection assembly 101 has a wavelength λ_mIn order to satisfy the Bragg conditionThe angle theta is incident to the surface of the first diffraction grating 1021, after being diffracted by the first diffraction grating 1021, the light propagates in the optical waveguide lens 1023 in a total reflection mode until the light propagates to the surface of the second diffraction grating 1022, and a part of the light beam is emitted after being diffracted by the second diffraction grating 1022 to form a first-order coupled-out light beam; the rest of the light beams continue to propagate to the surface of the second diffraction grating 1022 after undergoing total reflection once in the optical waveguide lens 1023, and similarly, a part of the light beams exit after being diffracted by the second diffraction grating 1022 to form a second-order coupled-out light beam; the rest of the light beams continue to propagate to the surface of the second diffraction grating 1022 for the third time after undergoing total reflection once in the optical waveguide lens 1023, and a part of the light beams are diffracted by the second diffraction grating 1022 and then emitted to form a third-order coupled light beam, and so on, and after being diffracted by the second diffraction grating 1022, a fourth-order coupled light beam … … and an nth-order coupled light beam are sequentially generated. Since the second diffraction grating 1022 has only a periodic grating structure in the longitudinal direction, diffraction can be performed only a plurality of times in the longitudinal direction, reaching a plurality of exit pupil expansions to reduce the design size of the projection assembly 101 in that direction, thereby increasing the field angle of the displayed image to some extent, whereas since no periodic grating structure is provided in the lateral direction, there is no effect of exit pupil expansion of the light beam in that direction.

Next, the relationship of change between the eye movement range size and the diffraction grating size in the case of no exit pupil expansion and exit pupil expansion will be explained.

Referring to fig. 4, fig. 4 is a diagram illustrating the relationship between the eye movement range size and the diffraction grating size without exit pupil expansion. In general, the performance criteria that a near-eye display device needs to achieve are: at exit pupil distance d_eyereliefEye movement range in X direction of_xThe corresponding viewing angle θ in the X direction is θ_xr-air+θ_xl-airWherein, theta_xr-airAnd theta_xl-airThe exit angle of the exit beam in the X direction in the air is indicated.

To meet the above performance requirements, the second diffraction grating 1022 is designed with at least the following dimensions in the X direction:

L2_x＝eyebox_x+d_eyerelief·(tan(θ_xr-air)+tan(θ_xl-air))

the first diffraction grating 1021 has a design dimension in the X direction of at least:

L1_x＝L2_x+d₀·(tan(θ_xr-glass)+tan(θ_xl-glass))

wherein, theta_xr-glassAnd theta_xl-glassAngle in X direction, d, representing outgoing light beam in the optical waveguide lens 1023₀Representing the distance a beam of 0 deg. field of view in the X direction travels in the optical waveguide mirror.

Typically, the performance requirements of a near-eye display device are: d_eyereliefAt 15mm, eyebox_xIs 6mm, and the corresponding field angle in the X direction is 20, that is, θ_xr-airAnd theta_xl-airAre all 10 degrees. At this time, L2 is calculated according to the above equation_xIs 11.29 mm.

Assuming that the refractive index of the optical waveguide lens 1023 is 1.5, the corresponding viewing angle in the X direction of the optical waveguide lens 1023 is θ_xr-glass＝θ_xl-glassFor convenience of calculation, assuming that the angle of total reflection of the light beam of the 0 ° field of view in the optical waveguide lens 1023 is 45 ° and the distance between the first diffraction grating 1021 and the second diffraction grating 1022 is 35mm, the distance d of propagation of the light beam of the 0 ° field of view in the optical waveguide lens 1023 is set to 6.6478 °₀About 49.497mm, at which time L1 calculated according to the above equation_xApproximately 22.828 mm.

That is, in order to ensure that the field of view is not lost in the eye movement range, the design size of the projection unit 101 of the near-eye display device in the X direction should be larger than 22.828mm, and the size of the projection unit 101 in the X direction is too large for the near-eye display device in the form of the portable glasses. To reduce the size of the projection assembly 101 in a near-eye device, the field angle in the X direction may be reduced. For example, the X-direction field angle is reduced from 20 ° to 6 °, which is generally required, so that the size of the projection module 101 can be reduced.

Referring to fig. 5, fig. 5 is a schematic of the relationship between the eye movement range size with exit pupil expansion and the size of the diffraction gratingFigure (a). The performance indexes that the known near-eye display device needs to achieve are: at exit pupil distance d_eyereliefEye movement range in the Y direction of_yThe corresponding viewing angle θ in the Y direction is θ_yr-air+θ_yl-airWherein, theta_yr-airAnd theta_yl-airIndicating the exit angle of the exiting light beam in the Y direction in air.

To meet the above performance requirements, the design dimension of the second diffraction grating 1022 in the Y direction is at least:

L2_y＝eyebox_y+d_eyerelief·(tan(θ_yr-air)+tan(θ_yl-air))

typically, the performance requirements of a near-eye display device are: d_eyereliefAt 15mm, eyebox_x9mm, corresponding to a field angle of 30 in the Y direction, i.e., θ_xr-airAnd theta_xl-airAre all 15 degrees. At this time, L2 is calculated according to the above equation_xIs 17.03 mm.

Since there is a function of expanding the exit pupil in the Y direction, it is only necessary that the total size of the exit pupil formed by piecing together all the light spots after the exit pupil is expanded is larger than 17.03mm, and the size of the light spot incident on the second diffraction grating is not required to be 17.03 mm. In this case, the exit pupil position of the projection module 101 may be set at the first diffraction grating 1021, and the exit pupil size of the projection module 101 in the Y direction may be larger than a critical value, where the critical value is related to the maximum total reflection step corresponding to the incident angle in the field angle range.

As an example, assume that the maximum total reflection step is L_tir-maxPupil size L for the receiving component_receive(if the receiving component is the human eye, then L_receiveTypically about 3mm), the threshold value is L_tir-max-L_receiveThat is, the exit pupil size of the projection module 101 in the Y direction is only larger than L_tir-max-L_receiveThe requirements can be met.

In general, the exit pupil size of the projection module in the Y direction is about 4mm, so the size of the projection module itself can be made small.

In summary, the size of the projection assembly 101 can be greatly reduced by way of exit pupil expansion. Therefore, in order to solve the problem that the size of the projection assembly 101 is too large, so that the near-to-eye display device cannot approach the common myopia glasses in shape, and meanwhile, in order to reduce the size of the projection assembly 101, if a two-dimensional surface relief grating is adopted, the problems of large processing difficulty, low volume production, high production cost and the like exist, the embodiment of the application provides the exposure device, the two-dimensional holographic diffraction grating can be prepared, the second diffraction grating 202 is replaced by the two-dimensional holographic diffraction grating, so that incident light beams can be diffracted for multiple times in two directions, and the exit pupil expansion in the two directions is realized.

Referring to fig. 6, fig. 6 is a schematic top view of another display assembly provided in the embodiments of the present application. The first diffraction grating 1021 couples the light beam in a certain spectral range of the projection component 101 into the optical waveguide lens 1023, and propagates in the optical waveguide lens 1023 to the surface of the second diffraction grating 1022 in the form of total reflection, and is coupled out of the optical waveguide lens 1023 through the second diffraction grating 1022, and is received by the receiving component.

The second diffraction grating 1022 in fig. 6 is a two-dimensional holographic diffraction grating, that is, a periodic grating structure is disposed in two directions, so that two-dimensional exit pupil expansion can be achieved in the two directions, and the size, design difficulty, and processing cost of the projection assembly 101 can be reduced.

Here, the first diffraction grating 1021 may be a one-dimensional diffraction grating or a two-dimensional diffraction grating, which is not limited in the embodiment of the present application, and the first diffraction grating 1021 is illustrated as a one-dimensional diffraction grating in the embodiment of the present application, and is not limited in the embodiment of the present application.

In addition, the diffractive effect of a diffraction grating on an optical beam can be essentially viewed as the result of the superposition of the wavevector of the incident optical beam and the wavevector of the diffraction grating. Therefore, it is assumed that the grating wave vector of the first diffraction grating 1021 in the XY plane is

The total grating wave vector of the second diffraction grating 1022 in the XY plane is

The wave vector of the incident light beam is

The wave vector of the coupled-out light beam

Can be expressed as:

in order to ensure that the display image of the receiving assembly is consistent with the projected image of the projecting assembly 101, it is necessary to ensure that

Therefore, the wave vector conditions that the first diffraction grating and the second diffraction grating need to satisfy at the time of design are:

next, a wave vector condition that the first diffraction grating and the second diffraction grating need to satisfy after the two-dimensional holographic diffraction grating is disposed in the display assembly 102 will be explained.

With continued reference to fig. 6, if the first diffraction grating 1021 has no wavevector in the X-direction, then the wavevectors in the two directions of the second diffraction grating 1022 are mirror-symmetric about the Y-axis. Based on the display assembly 102 shown in fig. 6, referring to fig. 7, fig. 7 is a wave vector superposition diagram of the first diffraction grating 1021 and the second diffraction grating 1022.

Wherein the content of the first and second substances,

representing the wavevector of the first diffraction grating 1021 in the XY plane,

and

respectively, represent wave vectors of the second diffraction grating 1022 in two directions in the XY plane.

And

regarding Y-axis mirror symmetry, the included angle between the Y-axis and the first diffraction grating 1021 and the second diffraction grating 1022 is α, and the following conditions need to be satisfied between the grating wave vectors:

the relationship between the grating period and the grating vector is known as

Therefore, the following condition needs to be satisfied between the grating periods of the first diffraction grating 1021 and the second diffraction grating 1022:

Λ_2-1＝Λ_2-2

Λ_2-1＝2·Λ₁·cosα

wherein, Λ₁Representing the grating period, Λ, of the first diffraction grating 1021_2-1And Λ_2-2Respectively, the grating periods of the second diffraction grating 1022 in two directions.

Referring to fig. 8, fig. 8 is a schematic top view of another display assembly provided in the embodiment of the present application, in which the first diffraction grating 1021 and the second diffraction grating 1022 have wave vectors in both X and Y directions. Based on the display assembly 102 shown in fig. 8, fig. 9 is a wave-vector superposition diagram of the first diffraction grating 1021 and the second diffraction grating 1022.

Wherein the content of the first and second substances,

and

The included angle between the Y axis and the Y axis is gamma,

the included angle between the Y axis and the Y axis is alpha,

if the angle between the grating wave vectors and the Y axis is β, the following conditions need to be satisfied between the grating wave vectors of the first diffraction grating 1021 and the second diffraction grating 1022:

the relationship between the grating period and the grating vector is known as

It should be noted that, in order to reduce the design size of the projection assembly 101, after the two-dimensional holographic diffraction grating is formed on the holographic diffraction substrate coated with the photopolymer material by using the exposure apparatus provided in the embodiment of the present application, the second diffraction grating in the display assembly 102 is replaced with the two-dimensional holographic diffraction grating. The grating periods of the first diffraction grating and the prepared two-dimensional holographic diffraction grating in the display assembly must meet the conditions, so that when the two-dimensional holographic diffraction grating is used in the near-eye display device, an image displayed by the display assembly and an image projected by the projection assembly can be kept consistent, and deformation and distortion cannot occur.

After the theoretical feasibility is analyzed, the process of manufacturing the two-dimensional holographic diffraction grating is explained by combining the exposure apparatus provided in the embodiment of the present application.

Fig. 10 is a schematic structural diagram of a first exposure apparatus provided in an embodiment of the present application, and refer to fig. 10. The exposure apparatus includes: the device comprises a laser 01, a light beam conversion assembly 02, a liquid crystal spatial light modulator 03, a beam splitting assembly 04, a first reflecting assembly 05, a second reflecting assembly 06 and a coupling assembly 07;

the laser 01 is used for emitting light beams, the liquid crystal spatial light modulator 03 is located on the light-in side of the beam splitting assembly 04, the light beam conversion assembly 02 is located on the light-in side of the liquid crystal spatial light modulator 03 or the light-out side of the beam splitting assembly 04, the liquid crystal spatial light modulator 03 is used for modulating the wave front phase distribution of the incident light beams, so that the light beams emitted by the liquid crystal spatial light modulator 03 have phase differences in two different directions, and the light beam conversion assembly 02 is used for converting the polarization direction of the incident light beams; the first reflection assembly 05 is located on a first light outgoing side of the beam splitting assembly 04, the second reflection assembly 06 is located on a second light outgoing side of the beam splitting assembly 04, the coupling assembly 07 is located in an overlapping area of the light outgoing side of the first reflection assembly 05 and the light outgoing side of the second reflection assembly 06, the coupling assembly 07 is used for bearing the holographic diffraction substrate 08 coated with the photopolymer material, and light beams emitted by the first reflection assembly 05 and the second reflection assembly 06 can form a two-dimensional holographic diffraction grating on the holographic diffraction substrate 08 coated with the photopolymer material.

The light beam emitted by the laser 01 may be a light beam with any wavelength, and a user may adjust the wavelength of the light beam emitted by the laser 01 according to an actual situation, which is not limited in the embodiment of the present application.

As one example, the laser light emitted from the laser 01 may include at least one of light in a red wavelength band, light in a green wavelength band, and light in a blue wavelength band.

The light beam conversion assembly 02 is used for converting the polarization direction of an incident light beam. That is, the light beam conversion assembly can adjust the intensity ratio of the P-polarized light to the S-polarized light in the incident light beam, and further control the emergent light beam to be the light beam in the same polarization state.

That is, the light beam conversion assembly 02 can completely convert P-polarized light in the incident light beam into S-polarized light, so that the emergent light beam is S-polarized light; the S-polarized light in the incident light beam can also be completely converted into P-polarized light, so that the emergent light beam is P-polarized light.

The liquid crystal spatial light modulator 03 can change the amplitude or intensity, phase, polarization state and wavelength of the spatial light beam distribution under the control of a time-varying electric drive signal or other signals, and can also convert incoherent light into coherent light.

In the embodiment of the present application, the role of the liquid crystal spatial light modulator 03 mainly includes two aspects:

on one hand, since the two-dimensional holographic diffraction grating needs to be formed in the embodiment of the present application, the wave vectors of the two-dimensional holographic diffraction grating as the second diffraction grating 1022 and the first diffraction grating 1021 applied in the display component 102 need to satisfy:

therefore, the wave vector of the two-dimensional hologram diffraction grating to be formed can be determined according to the wave vector of the first diffraction grating 1021 and the above expression, and the wavefront phase distribution of the incident light can be modulated by the liquid crystal spatial light modulator 03, so that the phase difference exists between the outgoing light of the liquid crystal spatial light modulator 03 in two different directions.

It should be noted that, as an example, two beams of light are generally used to perform interference exposure on the holographic diffraction substrate 08 coated with the photopolymer material to form a one-dimensional holographic diffraction grating, and after the interference exposure, a grating period is generated only in the vertical direction in the first surface of the holographic diffraction substrate 08, and no grating period is generated in the horizontal direction in the first surface of the holographic diffraction substrate 08, and the first surface of the holographic diffraction substrate 08 is coated with the photopolymer material. In the above process, because the phase difference generated by the two beams of light with the unmodulated wavefront phase distribution on the first surface of the holographic diffraction substrate 08 coated with the photopolymer material exists only in the vertical direction in the plane, the interference exposure produces the one-dimensional holographic diffraction grating. In order to prepare the two-dimensional holographic diffraction grating, it is necessary to additionally manufacture a phase difference of one in the horizontal direction within the first surface of the holographic diffraction substrate 08 by the liquid crystal spatial light modulator so that a phase difference exists in both the horizontal direction and the vertical direction within the first surface of the holographic diffraction substrate 08 when two beams are interference-exposed on the holographic diffraction substrate 08 coated with the photopolymer material.

The wavefront phase distribution of the incident beam is modulated, and stable additional phases exist in two directions, so that the phase difference existing in the horizontal direction and the vertical direction is not influenced by the conversion of the polarization state of the beam.

The horizontal direction and the vertical direction only indicate two different directions in the first plane of the holographic diffraction substrate 08, and the horizontal direction and the vertical direction may be two directions perpendicular to each other or two directions not perpendicular to each other, which is not limited in the embodiment of the present application.

On the other hand, the liquid crystal spatial light modulator 03 may also convert the polarization state of the light beam after the wavefront phase distribution is modulated, for example, convert S-polarized light into P-polarized light, or convert P-polarized light into S-polarized light, which is not limited in this embodiment of the application.

The liquid crystal spatial light modulator 03 includes: according to the spatial light modulator with a reflective structure and the spatial light modulator with a transmissive structure, a user can select the structure of the liquid crystal spatial light modulator 03 to be used according to the requirement of the optical path in the constructed exposure device, and the embodiment of the application is not limited to this.

The beam splitting assembly 04 is configured to split an incident light beam into two outgoing light beams.

In one possible implementation, the beam splitting component 04 may be a polarization beam splitter, and is configured to reflect S-polarized light and transmit P-polarized light, so as to split an incident light beam into two outgoing light beams according to a polarization state.

In another possible implementation manner, the beam splitting component 04 may be a beam splitter, and the beam splitter may split a single light beam with a single wavelength into two light beams, or may split light beams with multiple wavelengths, and in any case, there are generally reflected light and transmitted light. The proportion of the reflected light and the transmitted light is different according to the coating of the beam splitter, and the embodiment of the application does not limit the proportion.

As an example, the beam splitter has the same ratio of reflected light to transmitted light, i.e. an incoming light beam can be equally split into two outgoing light beams by the beam splitter.

Wherein the first reflecting assembly 05 and the second reflecting assembly 06 may comprise one mirror. Wherein, the parameters such as focal length, size of this speculum all can set up according to the user demand, and this application embodiment does not limit to this.

In addition, the coupling assembly 07 is located in an overlapping area of the light-emitting side of the first reflection assembly 05 and the light-emitting side of the second reflection assembly 06, the coupling assembly 07 is used for carrying a holographic diffraction substrate 08 coated with a photopolymer material, and the light beams emitted by the first reflection assembly 05 and the second reflection assembly 06 can form a two-dimensional holographic diffraction grating on the holographic diffraction substrate 08 coated with the photopolymer material. In the specific process, a photopolymer material is coated on the holographic diffraction substrate 08, the holographic diffraction substrate 08 coated with the photopolymer material is placed in the coupling component 07, the outgoing light beam of the first reflection component 05 and the outgoing light beam of the second reflection component 06 are subjected to interference exposure on the holographic diffraction substrate 08 of which the first surface is coated with the photopolymer material, and because two beams of light subjected to interference exposure have phase differences in two different directions in the first surface of the holographic diffraction substrate 08, light and dark alternate fringes in two directions can be formed inside the photopolymer material coated on the first surface, so that the two-dimensional holographic diffraction grating is obtained.

As an example, referring to fig. 10, coupling assembly 07 includes a triangular prism 071 and a trapezoidal prism 072; the first side surface 0711 of the triangular prism 071 faces the first reflection component 05, the second side surface 0712 of the triangular prism 071 is in contact with the first surface of the holographic diffraction substrate 08, an included angle between the first side surface 0711 and the second side surface 0712 of the triangular prism 071 is an acute angle, and the first surface of the holographic diffraction substrate 08 is coated with a photopolymer material; the lower bottom surface 0721 of the trapezoidal prism 072 is in contact with the second surface of the hologram diffraction substrate 08.

It should be noted that the triangular prism 071 can also be other prisms as long as the included angle between the first side surface 0711 and the second side surface 0712 is an acute angle, and fig. 9 is only illustrated by taking the rectangular triangular prism 071 as an example, and does not limit the embodiment of the present application.

In addition, since the light beam conversion component 02 may be located on the light incident side of the liquid crystal spatial light modulator 03 or on the light emergent side of the beam splitting component 04, when the light beam conversion component is deployed at different positions, the light paths in the exposure apparatus may also be different, and the process of forming the two-dimensional holographic diffraction grating may also be slightly different.

Next, the arrangement of the beam conversion module 03 and the process for manufacturing the two-dimensional holographic diffraction grating in the arrangement will be explained with reference to the drawings.

First, a case where the beam conversion member 02 is located on the light incident side of the liquid crystal spatial light modulator 03 will be explained.

It should be noted that, when the beam conversion assembly 02 is located on the light incident side of the liquid crystal spatial light modulator 03, the beam conversion assembly 02 includes the first half wave plate 021 and the polarization beam splitter 022, and the beam splitting assembly 04 includes the beam splitter 041.

In a possible implementation manner, the liquid crystal spatial light modulator 03 is located on the first light emitting side 0221 of the polarization beam splitter 022, and the liquid crystal spatial light modulator 03 may be a spatial light modulator with a reflective structure or a spatial light modulator with a transmissive structure. Here, the first light emitting side 0221 of the polarization beam splitter 022 is the light emitting side of the S-polarized light reflected by the polarization beam splitter 022.

As an example, with continued reference to fig. 10, the liquid crystal spatial light modulator 03 is a spatial light modulator of a reflective structure and is configured to modulate a wavefront phase distribution of S-polarized light so that the S-polarized light has a phase difference in two different directions and convert the S-polarized light into P-polarized light. The first half-wave plate 021 is configured to receive the light beam emitted by the laser 01 and convert the light beam into S-polarized light, the polarization beam splitter 022 is located on the light exit side of the first half-wave plate 021 and located between the liquid crystal spatial light modulator 03 and the beam splitter 041, and the first light exit side 0221 of the polarization beam splitter 022 faces the liquid crystal spatial light modulator 03 and faces away from the beam splitter 041.

In this example, the formation of a two-dimensional holographic diffraction grating on a photopolymer material coated holographic diffraction substrate 08 is achieved by: the laser 01 emits a laser beam, and the first half wave plate 021 receives the laser beam emitted by the laser 01 and converts the laser beam into S-polarized light. The S polarized light emitted from the first half-wave plate 021 is reflected by the polarization beam splitter 022 and then propagates to the liquid crystal spatial light modulator 03. The liquid crystal spatial light modulator 03 modulates the wavefront phase distribution of the S-polarized light so that the S-polarized light has a phase difference in two different directions, and converts the S-polarized light into P-polarized light.

The P-polarized light whose wavefront phase distribution is modulated is reflected back to the polarization beam splitter 022, and reaches the beam splitter 041 through the polarization beam splitter 022, and the beam splitter 041 equally divides the P-polarized light into two outgoing light beams.

The P-polarized light transmitted from the beam splitter 041 reaches the first reflection assembly 05, and after being reflected by the first reflection assembly 05, the P-polarized light reaches the coupling assembly 07. The P-polarized light can be regarded as object light, and the wavefront phase distribution of the object light is modulated by the liquid crystal spatial light modulator 03.

The P-polarized light reflected from the beam splitter 041 reaches the second reflecting component 06, and after being reflected by the second reflecting component 06, the P-polarized light reaches the coupling component 07. The P-polarized light can be regarded as the reference light, and the wavefront phase distribution of the reference light is modulated by the liquid crystal spatial light modulator 03.

The coupling assembly 07 may carry a holographic diffraction substrate 08 coated with a photopolymer material, and the object light is incident on the holographic diffraction substrate 08 coated with the photopolymer material after passing through the first side 0711 and the second side 0712 of the triangular prism 071, and the reference light is incident on the holographic diffraction substrate 08 coated with the photopolymer material after passing through the bottom 0721 of the trapezoidal prism 072. The object light and the reference light (which are both P-polarized light) of which the phase distribution of the wavefront is modulated by the liquid crystal spatial light modulator 03 are subjected to interference exposure on the holographic diffraction substrate 08 coated with the photopolymer material, and because the object light and the reference light have phase differences in two different directions in the first surface of the holographic diffraction substrate 08, light and dark alternate stripes in two directions can be formed inside the photopolymer material coated on the first surface, so that the two-dimensional holographic diffraction grating is obtained.

As another example, referring to fig. 11, fig. 11 is a schematic structural diagram of a second exposure apparatus provided in an embodiment of the present application. The liquid crystal spatial light modulator 03 is a spatial light modulator having a transmissive structure, and is configured to modulate a wavefront phase distribution of the S-polarized light, so that the S-polarized light has a phase difference in two different directions, and convert the S-polarized light into P-polarized light. The first half-wave plate 021 is configured to receive a light beam emitted by the laser 01 and convert the light beam into S-polarized light, the polarization beam splitter 022 is located on a light exit side of the first half-wave plate 021, the liquid crystal spatial light modulator 03 is located on a first light exit side 0221 of the polarization beam splitter 022, and the beam splitter 041 is located on a light exit side of the liquid crystal spatial light modulator 03.

The P-polarized light whose wavefront phase distribution is modulated transmits through the liquid crystal spatial light modulator 03 to the beam splitter 041, and the beam splitter 041 equally divides the P-polarized light into two outgoing light beams.

The P-polarized light transmitted from the beam splitter 041 reaches the first reflection assembly 05, and after being reflected by the first reflection assembly 05, the P-polarized light reaches the coupling assembly 07. The P-polarized light can be regarded as object light. The P-polarized light reflected from the beam splitter 041 reaches the second reflecting component 06, and after being reflected by the second reflecting component 06, the P-polarized light reaches the coupling component 07. The P-polarized light can be regarded as the reference light.

The coupling assembly 07 may carry a holographic diffractive substrate 08 coated with a photopolymer material, the wavefront phase distributions of the object and reference light (both P-polarized light) are modulated by a liquid crystal spatial light modulator 03, after the object light passes through the first side 0711 and the second side 0712 of a triangular prism 071, incident on the holographic diffraction substrate 08 coated with the photopolymer material, the reference light is incident on the holographic diffraction substrate 08 coated with the photopolymer material after passing through the bottom surface 0721 of the trapezoidal prism 072, the object light and the reference light are interference-exposed on the holographic diffraction substrate 08 coated with the photopolymer material, since the object light and the reference light have a phase difference in two different directions within the first surface of the hologram diffraction substrate 08, therefore, light and shade alternate stripes in two directions can be formed in the interior of the photopolymer material coated on the first surface, and the two-dimensional holographic diffraction grating is obtained.

In another possible implementation, the liquid crystal spatial light modulator 03 is located on the second light-emitting side 0222 of the polarization beam splitter 022, and the liquid crystal spatial light modulator 03 is a spatial light modulator with a transmissive structure. Here, the second light emitting side 0222 of the polarization beam splitter 022 is the light emitting side of the P-polarized light transmitted by the polarization beam splitter 022.

As an example, referring to fig. 12, fig. 12 is a schematic structural diagram of a third exposure apparatus provided in an embodiment of the present application. The liquid crystal spatial light modulator 03 is a spatial light modulator having a transmissive structure, and is configured to modulate a wavefront phase distribution of P-polarized light, so that the P-polarized light has a phase difference in two different directions, and convert the P-polarized light into S-polarized light. The first half-wave plate 021 is configured to receive a light beam emitted by the laser 01 and convert the light beam into P-polarized light, the polarization beam splitter 022 is located on a light exit side of the first half-wave plate 021, the liquid crystal spatial light modulator 03 is located on a second light exit side 0222 of the polarization beam splitter 022, and the beam splitter 041 is located on a light exit side of the liquid crystal spatial light modulator 03.

In this example, the formation of a two-dimensional holographic diffraction grating on a photopolymer material coated holographic diffraction substrate 08 is achieved by: the laser 01 emits a laser beam, and the first half wave plate 021 receives the laser beam emitted by the laser 01 and converts the laser beam into P-polarized light. The P polarized light emitted from the first half wave plate 021 is transmitted by the polarization beam splitter 022 and then propagates to the liquid crystal spatial light modulator 03. The liquid crystal spatial light modulator 03 modulates the wavefront phase distribution of the P-polarized light so that the P-polarized light has a phase difference in two different directions, and converts the P-polarized light into S-polarized light.

The S polarized light whose wavefront phase distribution is modulated transmits through the liquid crystal spatial light modulator 03 to the beam splitter 041, and the beam splitter 041 equally divides the S polarized light into two outgoing light beams.

The S-polarized light transmitted from the beam splitter 041 reaches the first reflection assembly 05, and after being reflected by the first reflection assembly 05, the S-polarized light reaches the coupling assembly 07. The S-polarized light can be regarded as object light. The S-polarized light reflected from the beam splitter 041 reaches the second reflecting component 06, and after being reflected by the second reflecting component 06, the S-polarized light reaches the coupling component 07. The S-polarized light can be regarded as the reference light.

The coupling assembly 07 may carry a holographic diffraction substrate 08 coated with a photopolymer material, the wavefront phase distributions of the object and reference light (also S-polarized light) are modulated by a liquid crystal spatial light modulator 03, after the object light passes through the first side 0711 and the second side 0712 of a triangular prism 071, incident on the holographic diffraction substrate 08 coated with the photopolymer material, the reference light is incident on the holographic diffraction substrate 08 coated with the photopolymer material after passing through the bottom surface 0721 of the trapezoidal prism 072, the object light and the reference light are interference-exposed on the holographic diffraction substrate 08 coated with the photopolymer material, since the object light and the reference light have a phase difference in two different directions within the first surface of the hologram diffraction substrate 08, therefore, light and shade alternate stripes in two directions can be formed in the interior of the photopolymer material coated on the first surface, and the two-dimensional holographic diffraction grating is obtained.

Next, a case where the beam conversion member 02 is located on the light outgoing side of the beam splitting member 04 will be explained.

It should be noted that, when the light beam conversion module 02 is located on the light exit side of the beam splitting module 04, the light beam conversion module 02 includes a second half-wave plate 023, and the beam splitting module 04 includes a polarization beam splitter 042. The liquid crystal spatial light modulator 03 is a spatial light modulator with a transmissive structure, and the liquid crystal spatial light modulator 03 is configured to receive a light beam emitted from the laser 01 and modulate a wavefront phase distribution of the light beam so that a phase difference exists between the light beam in two different directions.

It should be noted that the polarizing beam splitter 022 and the polarizing beam splitter 042 mentioned in the embodiment of the present application may be the same polarizing beam splitter, and only the disposition position in the exposure apparatus is different.

In a possible implementation manner, referring to fig. 13, fig. 13 is a schematic structural diagram of a fourth exposure apparatus provided in an embodiment of the present application. The polarization beam splitter 042 is located the light-emitting side of the liquid crystal spatial light modulator 03, the liquid crystal spatial light modulator 03 is used for receiving the light beam emitted by the laser 01, and modulate the wave front phase distribution of the light beam, so that the light beam has a phase difference in two different directions, the polarization beam splitter 042 is used for dividing the light beam after phase distribution modulation into P polarized light and S polarized light, and transmit the P polarized light and reflect the S polarized light, the second half-wave plate 023 is located between the polarization beam splitter 042 and the first reflection assembly 05, and the first light-emitting side 0421 of the polarization beam splitter 042 faces the second half-wave plate 023, and the second half-wave plate 023 is used for converting the S polarized light reflected by the polarization beam splitter 042 into the P polarized light.

In this implementation, the formation of the two-dimensional holographic diffraction grating on the photopolymer material coated holographic diffraction substrate 08 is achieved by: the laser 01 emits a laser beam, the liquid crystal spatial light modulator 03 receives the laser beam emitted by the laser 01 and modulates the wavefront phase distribution of the laser beam so that the phase difference exists between the laser beam and the light beam in two different directions, and the polarization beam splitter 042 is used for splitting the light beam modulated by the phase distribution into P-polarized light and S-polarized light.

The S-polarized light reflected by the polarization beam splitter 042 reaches the second half-wave plate 023, the second half-wave plate converts the S-polarized light reflected by the polarization beam splitter 042 into P-polarized light, the P-polarized light reaches the first reflection assembly 05, and the S-polarized light reaches the coupling assembly 07 after being reflected by the first reflection assembly 05. The P-polarized light can be regarded as object light.

The P-polarized light transmitted by the polarization beam splitter 042 reaches the second reflecting member 06, and after being reflected by the second reflecting member 06, the P-polarized light reaches the coupling member 07. The P-polarized light can be regarded as the reference light.

The coupling assembly 07 may carry a holographic diffraction substrate 08 coated with a photopolymer material, the wavefront phase distributions of the object and reference light (also P-polarized light) are modulated by a liquid crystal spatial light modulator 03, after the object light passes through the first side 0711 and the second side 0712 of a triangular prism 071, incident on the holographic diffraction substrate 08 coated with the photopolymer material, the reference light is incident on the holographic diffraction substrate 08 coated with the photopolymer material after passing through the bottom surface 0721 of the trapezoidal prism 072, the object light and the reference light are interference-exposed on the holographic diffraction substrate 08 coated with the photopolymer material, since the object light and the reference light have a phase difference in two different directions within the first surface of the hologram diffraction substrate 08, therefore, light and shade alternate stripes in two directions can be formed in the interior of the photopolymer material coated on the first surface, and the two-dimensional holographic diffraction grating is obtained.

In another possible implementation manner, referring to fig. 14, fig. 14 is a schematic structural diagram of a fifth exposure apparatus provided in an embodiment of the present application. The polarization beam splitter 042 is located the light-emitting side of the liquid crystal spatial light modulator 03, the liquid crystal spatial light modulator 03 is used for receiving the light beam emitted by the laser 01, and modulate the wave front phase distribution of the light beam, so that the light beam has a phase difference in two different directions, the polarization beam splitter 042 is used for dividing the light beam after phase distribution modulation into P polarized light and S polarized light, and transmits the P polarized light and reflects the S polarized light, the second half-wave plate 023 is located between the polarization beam splitter 042 and the second reflection assembly 06, and the second light-emitting side 0422 of the polarization beam splitter 042 faces the second half-wave plate 023, and the second half-wave plate 023 is used for converting the P polarized light transmitted by the polarization beam splitter 042 into the S polarized light.

The S-polarized light reflected by the polarization beam splitter 042 reaches the first reflecting member 05, and after being reflected by the first reflecting member 05, the S-polarized light reaches the coupling member 07. The S-polarized light can be regarded as object light.

The P-polarized light transmitted by the polarization beam splitter 042 reaches the second half-wave plate 023, the second half-wave plate 023 converts the P-polarized light transmitted by the polarization beam splitter 042 into S-polarized light, the S-polarized light reaches the second reflecting assembly 06, and the S-polarized light reaches the coupling assembly 07 after being reflected by the second reflecting assembly 06. The S-polarized light can be regarded as the reference light.

Further, based on the exposure apparatus shown in fig. 13 and 14 described above, a third half-wave plate 09 may be further included in the exposure apparatus.

Referring to fig. 15, fig. 15 is a schematic structural diagram of a sixth exposure apparatus provided in an embodiment of the present application. The third half-wave plate 09 is located between the laser 01 and the liquid crystal spatial light modulator 03, the third half-wave plate 09 is used for receiving the light beam emitted by the laser 01, and the liquid crystal spatial light modulator 03 is used for receiving the light beam emitted by the third half-wave plate 09.

The third half-wave plate 09 can adjust the intensity ratio of the P polarized light to the S polarized light in the incident light beam, and further control the intensity of the P polarized light and the S polarized light in the light beam incident to the liquid crystal spatial light modulator 03 according to the adjustment requirement of the user.

In addition, based on the method for forming the two-dimensional holographic diffraction grating on the holographic diffraction substrate 08 coated with the photopolymer material, if the two-dimensional holographic diffraction grating with uniform diffraction efficiency needs to be formed, the wavefront phase distribution and the amplitude of the incident beam are modulated by the liquid crystal spatial light modulator 03, so that the wavefront energy distribution of the emergent beam is uniform. If a two-dimensional holographic diffraction grating with gradually changed diffraction efficiency needs to be prepared, the wavefront phase distribution and the amplitude of an incident beam are modulated by the liquid crystal spatial light modulator 03, so that the wavefront energy distribution of an emergent beam is gradually changed. That is, if the spatial light modulator 03 modulates the wavefront phase distribution and amplitude of the incident light beam, the emitted light beam has a phase difference in two different directions, and the energy distribution of the wavefront changes gradually, and the light beam is split into the reference light and the object light after being split. Because the object light and the reference light have phase difference in two directions and the wavefront energy distribution of the reference light and the object light is gradually changed, the reference light and the object light are subjected to interference exposure on the holographic diffraction substrate 08 coated with the photopolymer material, and a two-dimensional holographic diffraction grating with gradually changed diffraction efficiency can be formed.

Here, when the two-dimensional holographic diffraction grating in which the diffraction efficiency is gradually changed is formed on the holographic diffraction substrate 08 coated with the photopolymer material, the diffraction efficiency can be adjusted by adjusting the refractive index modulation degree of the photopolymer material. The higher the refractive index modulation of the photopolymer material, the higher the diffraction efficiency of the grating. Generally, the diffraction efficiency of the grating can be about 95% at the maximum and about 5% at the minimum. The refractive index modulation degree is closely related to the exposure dose, which is the product of the exposure intensity and the exposure time, and when the amount of the exposure agent reaches a certain value, saturation exposure is performed, and in the case of saturation exposure, high diffraction efficiency can be obtained. When the required diffraction efficiency is small, unsaturated exposure can be adopted, that is, when the amount of the exposure agent is small, unsaturated exposure is adopted, and in the case of unsaturated exposure, lower diffraction efficiency can be obtained. Therefore, the diffraction efficiency of the two-dimensional holographic diffraction grating can be regulated and controlled by controlling the exposure intensity and the exposure time.

It should be noted that, in order to ensure the effect of interference exposure, the polarization states of the reference light and the object light mentioned above are the same, i.e. both P-polarized light and both S-polarized light.

After describing the case of the disposition position of the beam conversion section 02 in the exposure apparatus, other optical elements that the exposure apparatus may further include will be explained based on the exposure apparatus shown in fig. 10.

Optionally, in order to enable the exposure apparatus provided in the embodiment of the present application to move the position of the optical element as little as possible after being built, a device capable of flexibly adjusting the mirror may be further added to the first reflection assembly 05 and the second reflection assembly 06, for example: turntables, slide rails, and the like.

The turntable can rotate around the central shaft of the base, the angle of the reflector for receiving the incident light beam can be flexibly adjusted by using the turntable, the direction of the incident angle sliding rail of the incident light beam incident to the coupling component 07 can be adjusted to be parallel to the direction of the incident light beam of the reflector, the sliding rail can drive the turntable to move, and the distance between the reflector and the coupling component 07 is adjusted.

That is, if the coupling component 07 bears the holographic diffraction substrate 08 coated with the photopolymer material, the incident angle and the incident position of the object light and the reference light on the holographic diffraction substrate 08 coated with the photopolymer material can be flexibly adjusted by using the turntable and the slide rail, and then the diffraction grating with gradually changed diffraction efficiency is formed according to the interference exposure of the object light and the reference light.

As an example, referring to fig. 16, fig. 16 is a schematic structural diagram of a seventh exposure apparatus provided in an embodiment of the present application, in which a first reflection assembly 05 includes a first reflection mirror 051, a first rotating disc 052, and a first slide rail 053. The first reflector 051 is fixed on the first rotary table 052, the first rotary table 052 is positioned on the first slide rail 053 and can slide along the first slide rail 053, and the length direction of the first slide rail 053 is parallel to the direction of the incident light of the first reflector 051.

Similarly, second reflective assembly 06 includes second reflective mirror 061, second rotatable disc 062, and second sliding rail 063. The second reflecting mirror 061 is fixed on the second rotating disc 062, the second rotating disc 062 is located on the second sliding rail 063 and can slide along the second sliding rail 063, and the length direction of the second sliding rail 063 is parallel to the direction of the incident light of the second reflecting mirror 061.

It should be noted that in this embodiment of the application, only the first reflection assembly 05 may be provided and include the first reflection mirror 051, the first rotating disc 052 and the first slide rail 053, and the second reflection assembly 06 is not provided with the rotating disc and the slide rail; the second reflecting component 06 can also be provided with a second reflecting mirror 061, a second rotating disc 062 and a second sliding rail 063, and the first reflecting component 05 is not provided with a rotating disc and a sliding rail; it is also possible to provide both the first and

second reflection assemblies

05 and 06 with a turntable and a slide rail, as shown in fig. 15. The embodiment of the present application is explained by only using the first reflective assembly 05 and the second reflective assembly 06 both provided with the turntable and the slide rail as examples, and does not limit the embodiment of the present application.

Optionally, based on the exposure apparatus shown in fig. 16, the exposure apparatus further includes a collimated beam expanding assembly 10 for adjusting the light beam emitted from the laser 01.

Referring to fig. 17, fig. 17 is a schematic structural diagram of an eighth exposure apparatus provided in the embodiment of the present application. The collimation and beam expansion assembly 10 is located on the light emitting side of the laser 01, and the collimation and beam expansion assembly 10 is used for converting light beams emitted by the laser 01 into parallel light and increasing the width of the parallel light.

As an example, the collimated beam expanding assembly 10 includes a collimator lens 101 and an objective lens 102, the collimator lens 101 is located on the light emitting side of the laser 01, the objective lens 102 is located on the light emitting side of the collimator lens 91, the collimator lens 101 is used for converting the light beam emitted from the laser 01 into parallel light, and the objective lens 102 is used for increasing the width of the parallel light.

That is, the collimated beam expanding assembly 10 can enlarge the spot diameter and the divergence angle of the laser beam emitted from the laser 01, so that the emitted laser beam is closer to the collimated beam, thereby obtaining the wide beam parallel light.

Besides, the collimated beam expanding assembly 10 may also include other optical lenses as long as the beam emitted from the laser 01 can be converted into a wide beam parallel light, which is not limited in the embodiment of the present application.

Alternatively, based on the exposure apparatus shown in fig. 17 described above, the exposure apparatus further includes a third mirror 11.

Referring to fig. 18, fig. 18 is a schematic structural diagram of a ninth exposure apparatus provided in the embodiment of the present application. The third reflector 11 is located on the light exit side of the laser 01 and on the light entrance side of the collimating and beam expanding assembly 10, and the third reflector 11 is configured to reflect the light beam emitted from the laser 01 to the collimating and beam expanding assembly 10.

It should be noted that the position of the laser 01 is generally fixed, and in order to flexibly adjust the angle of the laser beam emitted by the laser 01, the direction of the emitted beam of the laser 01 and the center of the collimating lens 10 are located on the same horizontal line. That is, the angle of the laser beam emitted by the laser 01 can be flexibly adjusted by adding the third reflecting mirror 11.

In summary, in the embodiment of the present application, the liquid crystal spatial light modulator 03 modulates the wavefront phase distribution of the incident light beam, so that the phase difference exists between the emergent light beam in two different directions, and then the two light beams with the phase difference in two different directions are subjected to interference exposure in the photopolymer material, so as to form the two-dimensional holographic diffraction grating. That is, in the embodiment of the present application, the liquid crystal spatial light modulator 03 is used to modulate the wavefront of the generated two-dimensional holographic diffraction grating, and then the modulated light beam is used to perform holographic interference exposure on the holographic diffraction substrate 08 coated with the photopolymer material to form the two-dimensional holographic diffraction grating, so that the manufacturing difficulty and cost of the two-dimensional holographic diffraction grating are reduced, and the preparation yield of the two-dimensional holographic diffraction grating is improved.

All the above optional technical solutions can be combined arbitrarily to form an optional embodiment of the present invention, and details of the embodiment of the present application are not repeated.

It should be understood that reference to "a plurality" herein means two or more. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.

It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, where the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that are within the spirit and principle of the embodiments of the present invention should be included in the scope of the embodiments of the present invention.

Claims

1. An exposure apparatus characterized by comprising: the device comprises a laser (01), a light beam conversion assembly (02), a liquid crystal spatial light modulator (03), a beam splitting assembly (04), a first reflecting assembly (05), a second reflecting assembly (06) and a coupling assembly (07);

the laser (01) is used for emitting light beams, the liquid crystal spatial light modulator (03) is located on the light-in side of the beam splitting assembly (04), the light beam conversion assembly (02) is located on the light-in side of the liquid crystal spatial light modulator (03) or the light-out side of the beam splitting assembly (04), the liquid crystal spatial light modulator (03) is used for modulating the wave front phase distribution of the incident light beams, so that the light beams emitted by the liquid crystal spatial light modulator (03) have phase differences in two different directions, and the light beam conversion assembly (02) is used for converting the polarization direction of the incident light beams;

first reflection subassembly (05) are located the first light-emitting side of beam splitting subassembly (04), second reflection subassembly (06) are located the second light-emitting side of beam splitting subassembly (04), coupling subassembly (07) are located the light-emitting side of first reflection subassembly (05) with the overlap region of the light-emitting side of second reflection subassembly (06), coupling subassembly (07) are used for bearing the holographic diffraction base plate (08) that has the coating of photopolymer material, just first reflection subassembly (05) with the light beam of second reflection subassembly (06) outgoing is scribbled and is being scribbled and can form the holographic diffraction grating of two-dimentional on the holographic diffraction base plate (08) of photopolymer material.

2. The exposure apparatus according to claim 1, wherein the beam conversion assembly (02) comprises a first half wave plate (021) and a polarizing beam splitter (022), the beam splitting assembly (04) comprising a beam splitter (041);

the first half wave plate (021) is positioned at the light outgoing side of the laser (01), and the first half wave plate (021) is used for receiving a light beam emitted by the laser (01) and converting the light beam into S-polarized light;

the polarization beam splitter (022) is located on the light outgoing side of the first half-wave plate (021) and located between the liquid crystal spatial light modulator (03) and the beam splitter (041), the first light outgoing side (0221) of the polarization beam splitter (022) faces the liquid crystal spatial light modulator (03) and faces away from the beam splitter (041), and the liquid crystal spatial light modulator (03) is a spatial light modulator with a reflective structure and is used for modulating the wavefront phase distribution of the S-polarized light, so that the S-polarized light has a phase difference in two different directions and is converted into the P-polarized light;

wherein a first light exit side (0221) of the polarizing beam splitter (022) is a light exit side of the S-polarized light reflected by the polarizing beam splitter (022).

3. The exposure apparatus according to claim 1, wherein the beam conversion assembly (02) comprises a first half wave plate (021) and a polarizing beam splitter (022), the beam splitting assembly (04) comprising a beam splitter (041);

the polarization beam splitter (022) is located on the light outgoing side of the first half-wave plate (021), the liquid crystal spatial light modulator (03) is located on the first light outgoing side (0221) of the polarization beam splitter (022), the beam splitter (041) is located on the light outgoing side of the liquid crystal spatial light modulator (03), and the liquid crystal spatial light modulator (03) is a spatial light modulator with a transmission structure and is used for modulating the wave front phase distribution of the S polarized light so that the S polarized light has phase differences in two different directions and converting the S polarized light into P polarized light;

4. The exposure apparatus according to claim 1, wherein the beam conversion assembly (02) comprises a first half wave plate (021) and a polarizing beam splitter (022), the beam splitting assembly (04) comprising a beam splitter (041);

the first half wave plate (021) is positioned at the light outgoing side of the laser (01), and the first half wave plate (021) is used for receiving a light beam emitted by the laser (01) and converting the light beam into P polarized light;

the polarization beam splitter (022) is located on the light outgoing side of the first half-wave plate (021), the liquid crystal spatial light modulator (03) is located on the second light outgoing side (0222) of the polarization beam splitter (022), the beam splitter (041) is located on the light outgoing side of the liquid crystal spatial light modulator (03), and the liquid crystal spatial light modulator (03) is a spatial light modulator with a transmission structure and is used for modulating the wave front phase distribution of the P polarized light, so that the P polarized light has phase differences in two different directions and is converted into S polarized light;

wherein a second light exit side (0222) of the polarizing beam splitter (022) is the light exit side of the P-polarized light transmitted by the polarizing beam splitter (022).

5. The exposure apparatus according to claim 1, wherein the beam splitting assembly (4) comprises a polarizing beam splitter (042), and the beam converting assembly (02) comprises a second half-wave plate (023);

the polarization beam splitter (042) is located on the light outgoing side of the liquid crystal spatial light modulator (03), the liquid crystal spatial light modulator (03) is a spatial light modulator with a transmission structure, the liquid crystal spatial light modulator (03) is used for receiving light beams emitted by the laser (01) and modulating wave front phase distribution of the light beams so that the light beams have phase differences in two different directions, and the polarization beam splitter (042) is used for dividing the light beams after phase distribution modulation into P polarized light and S polarized light, transmitting the P polarized light and reflecting the S polarized light;

the second half-wave plate (023) is located between the polarizing beam splitter (042) and the first reflecting component (05), and a first light exit side (0421) of the polarizing beam splitter (042) faces the second half-wave plate (023), the second half-wave plate (023) is used for converting S-polarized light reflected by the polarizing beam splitter (042) into P-polarized light.

6. The exposure apparatus according to claim 1, wherein the beam splitting assembly (04) comprises a polarizing beam splitter (042), and the beam converting assembly (02) comprises a second half-wave plate (023);

the second half wave plate (023) is located between the polarizing beam splitter (042) and the second reflecting component (06), and a second light exit side (0422) of the polarizing beam splitter (042) faces the second half wave plate (023), the second half wave plate (023) is used for converting the P polarized light transmitted by the polarizing beam splitter (042) into S polarized light.

7. An exposure apparatus according to claim 5 or 6, further comprising a third half-wave plate (09);

the third half-wave plate (09) is located between the laser (01) and the liquid crystal spatial light modulator (03), the third half-wave plate (09) is used for receiving the light beam emitted by the laser (01), and the liquid crystal spatial light modulator (03) is used for receiving the light beam emitted by the third half-wave plate (09).

8. The exposure apparatus according to any one of claims 1 to 7, wherein the first reflection assembly (05) comprises a first mirror (051), a first turntable (052), and a first slide (053);

first speculum (051) is fixed in on first carousel (052), first carousel (052) is located on first slide rail (053), and can along first slide rail (053) slide, the length direction of first slide rail (053) with the direction of the incident light of first speculum (051) is parallel.

9. The exposure apparatus according to any one of claims 1 to 7, wherein the second reflection assembly (06) comprises a second reflection mirror (061), a second turntable (062), and a second slide rail (063);

the second reflecting mirror (061) is fixed on a second rotating disc (062), the second rotating disc (062) is positioned on the second sliding rail (063) and can slide along the second sliding rail (063), and the length direction of the second sliding rail (063) is parallel to the direction of incident light of the second reflecting mirror (061).

10. The exposure apparatus according to claim 1, wherein the coupling member (07) includes a triangular prism (071) and a trapezoidal prism (072);

a first side surface (0711) of the triangular prism (071) faces the first reflection component (05), a second side surface (0712) of the triangular prism (071) is in contact with a first surface of the holographic diffraction substrate (08), an included angle between the first side surface (0711) and the second side surface (0712) of the triangular prism (071) is an acute angle, and the first surface of the holographic diffraction substrate (08) is coated with the photopolymer material;

the lower bottom surface (0721) of the trapezoidal prism (072) is in contact with the second surface of the holographic diffraction substrate (08).

11. The exposure apparatus according to claim 1, further comprising a collimated beam expanding assembly (10);

the collimation and beam expansion assembly (10) is located on the light emitting side of the laser (01), and the collimation and beam expansion assembly (10) is used for converting light beams emitted by the laser (01) into parallel light and increasing the width of the parallel light.

12. The exposure apparatus according to claim 11, wherein the collimated beam expanding assembly (10) includes a collimator lens (101) and an objective lens (102);

collimating lens (101) are located the light-emitting side of laser instrument (01), objective lens (102) are located the light-emitting side of collimating lens (101), collimating lens (101) are used for with the light beam of laser instrument (01) outgoing converts the collimated light into parallel light, objective lens (102) are used for increasing the width of parallel light.

13. The exposure apparatus according to claim 11 or 12, further comprising a third mirror (11);

third speculum (11) are located the light-emitting side of laser instrument (01) and are located the income light side of collimation beam expanding subassembly (10), third speculum (11) are used for with the light beam reflection of laser instrument (01) outgoing extremely collimation beam expanding subassembly (10).

14. A near-eye display device characterized in that it comprises a two-dimensional holographic diffraction grating formed by the exposure apparatus of any one of claims 1 to 13.