Exposure device

Abstract

The utility model belongs to the technical field of volume holographic gratings, and discloses an exposure device which is used for exposing a holographic photosensitive material to manufacture a volume holographic grating. The exposure device comprises an exposure system and a first adjusting assembly, the exposure system is used for emitting signal light and reference light to a holographic photosensitive material, the first adjusting assembly is arranged on a light path of the signal light and / or the reference light, and the first adjusting assembly comprises a clamping seat and a replaceable diaphragm located on the light path. The diaphragm is a part machined and formed according to a design drawing, is movably mounted on the clamping seat for replacement, and is used for adjusting the light distribution of the signal light or the reference light of the light path on the holographic photosensitive material. The diaphragm is movably mounted on the clamping seat, so that the diaphragm can be machined as an independent part, the shape and the size of the diaphragm can be customized strictly according to a design drawing, and the accuracy of the shape of the diaphragm and the exposure quality are ensured. And adhesive tape pasting and cutting are not needed when the diaphragm is replaced, so that the exposure efficiency is improved.

Description

Technical Field

[0001] This solution belongs to the technical field of volume holographic gratings, and specifically relates to an exposure device for exposing holographic photosensitive materials to fabricate volume holographic gratings. Background Art

[0002] Today, with the rapid development of technology, augmented reality (AR) technology is gradually penetrating every corner of our lives with its unique charm and is widely used in many fields such as education, entertainment, medical care, and industrial manufacturing. As the core carrier of this technology, the performance of the optical display system of AR devices is directly related to user experience and market acceptance. Currently, the AR display systems on the market generally use a microdisplay and an optical combiner to achieve the fusion of virtual information and the real world. The optical combiner is a combination of various optical elements such as prisms, free-form surfaces, BirdBath, and optical waveguides, and its design is particularly crucial and is also the key part to distinguish AR display systems. Among many optical combination solutions, the optical waveguide solution is regarded as the most promising technical path due to its excellent optical effects, compact appearance, and good mass production prospects.

[0003] Optical waveguides can generally be divided into two categories: geometric optical waveguides and diffractive optical waveguides. Geometric optical waveguides are so-called array optical waveguides, which achieve image output and expansion of the eye movement frame through the stacking of array mirrors. Although this technology can provide clear image quality, its complex manufacturing process and high cost limit its wide application in the consumer market. Diffractive optical waveguides mainly include surface relief optical waveguides and volume holographic optical waveguides. Surface relief optical waveguides can be mass-produced by nanoimprinting technology, which has attracted great interest from AR optical module manufacturers. It has the advantages of a large field of view and a large eye movement range, but it also brings problems such as light leakage and environmental light rainbow patterns. At the same time, the related micro-nano processing technology is also a huge challenge. The volume holographic grating in the volume holographic optical waveguide is a Bragg grating, which will be diffracted with extremely high diffraction efficiency when the incident light wavelength and angle meet the Bragg matching conditions. Therefore, it has good angle selectivity and wavelength selectivity. These two characteristics can greatly suppress light leakage and environmental light rainbow patterns. In addition, the volume holographic grating also has the advantages of high diffraction efficiency, fast development and iteration, large-area preparation, and low cost.

[0004] The holographic volume grating waveguide is fabricated based on holographic interference technology and usually uses the two-beam interference method for exposure. As Figure 1As shown, the double-beam interference method mainly uses two coherent light beams to irradiate a holographic photosensitive material at a certain angle. Due to the interference of the two light beams, an interference pattern, that is, a periodic intensity change, is formed inside the material, thus forming a grating in the holographic photosensitive material. However, in existing volume holographic grating exposure devices, the diaphragm is made by pasting and cutting tape between two movable baffles to block the ineffective light beam and allow the effective light beam to pass through. When replacing the diaphragm, it is necessary to paste and cut the tape again, and the replacement process is very inconvenient. Moreover, the shape of the tape pasted and cut usually deviates greatly from the designed diaphragm shape, seriously affecting the exposure quality. Utility Model Content

[0005] This solution aims to overcome at least one defect in the prior art and provides an exposure device that is convenient for replacing the diaphragm and is conducive to improving the accuracy of the diaphragm shape.

[0006] To solve the above technical problems, this solution proposes an exposure device for exposing a holographic photosensitive material to produce a volume holographic grating. The exposure device includes an exposure system and a first adjustment component. The exposure system is used to emit a signal light beam and a reference light beam to the holographic photosensitive material. A first adjustment component is provided on the optical path of the signal light beam and / or the reference light beam. The first adjustment component includes a card seat and a replaceable diaphragm located on the optical path. The diaphragm is a part machined according to the design drawing, and is movably installed on the card seat for replacement, and is used to adjust the light distribution of the signal light beam or the reference light beam on the holographic photosensitive material in the optical path where it is located.

[0007] The above solution uses the card seat to movably install the diaphragm, so that the diaphragm can be machined as an independent part. Therefore, the shape and size of the diaphragm can be customized strictly according to the design drawing, thus ensuring the accuracy of the diaphragm shape. This accuracy is crucial for the exposure device because it directly affects the light distribution of the signal light beam and the reference light beam on the holographic photosensitive material, and thus affects the final exposure quality. When replacing the diaphragm, it is only necessary to remove the diaphragm installed on the card seat and then install a new diaphragm that meets the light distribution requirements, without the need for pasting and cutting the tape, which is conducive to improving the exposure efficiency.

[0008] The holder is preferably configured with a connecting member, a first clamping member, and a second clamping member, the first clamping member and the second clamping member being symmetrically arranged on the connecting member; a first clamping slot is provided on the first clamping member, and a second clamping slot is provided on the second clamping member. The first clamping slot and the second clamping slot are arranged opposite and spaced apart from each other, forming a space therebetween for accommodating the diaphragm. The two opposing edges of the diaphragm are respectively inserted into the first clamping slot and the second clamping slot for movable installation. This structural design of the holder provides great convenience and stability for the movable installation of the diaphragm, making the exposure device more flexible and efficient in adjusting light distribution, providing a strong guarantee for the production of high-quality volume holographic gratings, and ensuring the balance and stability of the diaphragm during installation, avoiding diaphragm displacement or loosening due to improper installation, and facilitating the positional accuracy of the diaphragm.

[0009] The first adjustment assembly is preferably equipped with a base, to which the holder is fixedly mounted. The base provides a stable support platform for the holder, ensuring the stability of the holder and the replaceable aperture mounted thereon during the exposure process. This stability is crucial for precisely controlling the optical paths of the signal and reference light, helping to reduce exposure errors caused by vibration or displacement, and further improving the stability and consistency of exposure quality. The holder, equipped with the aforementioned connector, first clamping member, and second clamping member, can be fixedly mounted to the base via the connection between the connector and the base.

[0010] The exposure apparatus is preferably equipped with a second adjustment component, located within the optical path of the signal light and / or reference light. This second adjustment component comprises a rotatable mirror positioned within the optical path, which is used to adjust the angle of incidence of the signal light or reference light in that optical path on the holographic photosensitive material. The rotatable mirror allows the operator to precisely adjust the angle of incidence of the signal light and / or reference light on the holographic photosensitive material. This adjustment capability is crucial for producing volume holographic gratings with specific diffraction efficiency and angular selectivity, as it allows the grating's performance to be optimized for specific application requirements. Adjusting the angle of incidence by rotating the mirror significantly reduces exposure preparation time and improves production efficiency.

[0011] The second adjustment component is preferably equipped with a rotating mechanism, which is connected to the reflector and drives the reflector to rotate around the rotation center to adjust the incident angle of the signal light or reference light in the optical path on the holographic photosensitive material. Controlling the rotation of the reflector by the rotating mechanism is conducive to improving the rotation accuracy of the reflector, thereby improving the accuracy of the incident angles θ1 and θ2. Specifically, the rotating mechanism can adopt an electric rotating mechanism such as an electric rotating stage and an electric angle stage to electrically control the rotation of the reflector. This not only avoids manual adjustment and further improves the efficiency of making volume holographic gratings, but also enables the exposure angle to be precisely controlled, greatly improving the production accuracy of volume holographic gratings.

[0012] The second adjustment component can be configured with a first lens and a second lens, and the first lens and the second lens are sequentially arranged on the optical path between the reflector and the holographic photosensitive material, the optical axis of the first lens coincides with the optical axis of the second lens, the first lens has a first focus, the second lens has a second focus, the first focus and the second focus coincide and are located between the first lens and the second lens, the first lens and the second lens have a first base point and a second base point, the first base point and the second base point are conjugate and are both located on the optical axis, the first base point is located on the side of the first lens facing away from the second lens, and coincides with the rotation center of the reflector, the rotation center is located on the reflection surface of the reflector, and the second base point is located on the side of the second lens facing away from the first lens, and coincides with the holographic photosensitive material. The coordinated action of the first and second lenses ensures that the incident angle of the signal light or reference light on the holographic photosensitive material changes while the illuminated area remains essentially unchanged. This allows the reflector to change its incident angle on the holographic photosensitive material simply by rotating a certain angle, without having to move its position. This also ensures that the adjusted signal light or reference light consistently impinges on the holographic photosensitive material and interferes with it, even ensuring that the center of the illuminated area of the holographic photosensitive material consistently coincides with the second focal point of the second lens, significantly improving the efficiency of volume holographic grating production. If a second adjustment component is provided in both the signal light and reference light optical paths, the second base point of the adjustment component located in the signal light path coincides with the second base point of the adjustment component located in the reference light path, facilitating that the illuminated area of the signal light and the illuminated area of the reference light on the holographic photosensitive material overlap as much as possible.

[0013] The second adjustment assembly can also be equipped with a displacement mechanism, which is connected to the reflector and drives the reflector to move so that the area illuminated by the signal light on the holographic photosensitive material substantially overlaps the area illuminated by the reference light on the holographic photosensitive material. Controlling the movement of the reflector through the displacement mechanism helps improve the movement precision of the reflector. Specifically, the displacement mechanism can adopt an electric translation stage, an electric lifting stage, or other electric movement mechanism to electrically control the rotation and movement of the reflector. This not only eliminates manual adjustment but also enables precise control of the exposure position, improving the efficiency and precision of volume holographic grating production.

[0014] The second adjustment assembly is preferably equipped with a rotary movement mechanism, which can be considered a combined rotational and movement mechanism. The rotary movement mechanism is connected to the reflector, driving the reflector to rotate about its rotation center to adjust the angle of incidence of the signal light or reference light in the corresponding optical path on the holographic photosensitive material. The mechanism also drives the reflector to move so that the illumination area of the signal light on the holographic photosensitive material substantially overlaps the illumination area of the reference light on the holographic photosensitive material. Specifically, the rotary movement mechanism can employ an electric displacement mechanism, such as an electric multi-dimensional combination stage, to electrically control the rotation and movement of the reflector. This not only eliminates manual adjustment but also enables precise control of the exposure angle and exposure position, thereby improving the efficiency and accuracy of volume holographic grating production.

[0015] Compared to existing technologies, this solution offers the following advantages: The diaphragm is removably mounted on a holder, allowing it to be machined as a separate component. Therefore, its shape and dimensions can be customized strictly according to the design drawings, ensuring precise diaphragm shape. This precision is crucial for exposure equipment, as it directly affects the distribution of signal and reference light on the holographic photosensitive material, and thus the final exposure quality. When replacing the diaphragm, simply remove the diaphragm mounted on the holder and replace it with a new one that meets the required light distribution. This eliminates the need for tape application and cutting, improving exposure efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the present invention. To better illustrate the present invention, some components in the accompanying drawings may be omitted, enlarged, or reduced in size, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0017] Figure 1 Schematic diagram of two-beam interference.

[0018] Figure 2 This is a schematic diagram of the exposure light path of the volume holographic grating.

[0019] Figure 3 This is a schematic diagram of the reproduction optical path of the volume holographic grating.

[0020] Figure 4 It is a structural schematic diagram of an exposure device in which the signal light path is equipped with a first adjustment component.

[0021] Figure 5 It is a structural schematic diagram of an exposure device in which a reference light path is equipped with a first adjustment component.

[0022] Figure 6 It is a structural schematic diagram of an exposure device in which both the signal light and reference light optical paths are equipped with first adjustment components.

[0023] Figure 7 It is a schematic structural diagram of a first adjustment component from a certain perspective.

[0024] Figure 8 It is a schematic structural diagram of a first adjustment component from another perspective.

[0025] Figure 9 It is a schematic diagram of the aperture replacement of the first adjustment component.

[0026] Figure 10 It is a schematic structural diagram of an exposure device in which the signal light optical path is equipped with a second adjustment component.

[0027] Figure 11 It is a schematic structural diagram of an exposure device in which the reference light optical path is equipped with a second adjustment component.

[0028] Figure 12 It is a schematic structural diagram of an exposure device in which both the signal light and reference light optical paths are equipped with a second adjustment component.

[0029] Figure 13 It is a schematic structural diagram of an exposure device in which the second adjustment component uses a third lens group.

[0030] Figure 14 It is a schematic structural diagram of an exposure device in which the second adjustment components on both the signal light and reference light optical paths use a third lens group.

[0031] Figure 15 It is a schematic structural diagram of an exposure device in which the second adjustment component uses a moving mechanism.

[0032] Explanation of reference numerals: Holographic photosensitive material 001, volume holographic grating 002, exposure system 100, signal light generator 110, reference light generator 120, first adjustment system 200, first adjustment components 210, 220, aperture 201, card seat 202, connecting member 2021, first clamping member 2022, second clamping member 2023, first card slot 2024, second card slot 2025, base 203, second adjustment system 300, second adjustment components 310, 320, mirror 301, rotating mechanism 302, first lens 303, second lens 304, moving mechanism 305. Detailed implementation manners

[0033] In order to enable those skilled in the art to better understand this solution, the following further elaborates on this solution in conjunction with specific embodiments.

[0034] Figures 2 - 3 It schematically shows the exposure optical path and the reproduction optical path of the volume holographic grating. The volume holographic grating is made of the holographic photosensitive material 001, and the signal light and the reference light irradiate on the holographic photosensitive material 001 to form two-beam interference, as Figure 2, the holographic photosensitive material 001 records the interference fringe distribution in the form of refractive index change distribution, and the fringes correspond to the desired grating structure, thus obtaining a volume holographic grating. The reproduction optical path of the obtained volume holographic grating is as shown in Figure 3 . When light is incident on the volume holographic grating 002 along the reference light direction, it extends, generating direct transmitted light L0 (0th order light) and diffracted light L +1 (+1st order light). The direction of the direct transmitted light is the same as that of the reference light, and the direction of the diffracted light is the same as that of the signal light. Therefore, after using the reference light to record the signal light on the holographic photosensitive material 001 to form the volume holographic grating 002, the signal light can be reproduced by the light whose direction is the same as that of the reference light.

[0035] Figures 4 - 15 shows an exposure device for exposing the holographic photosensitive material to fabricate a volume holographic grating. The exposure device is configured with an exposure system 100 and a first adjustment system 200. The exposure system 100 is used to emit signal light and reference light to the holographic photosensitive material 001, and the first adjustment system 200 is used to adjust the light distribution of the signal light and / or the reference light on the holographic photosensitive material 001.

[0036] The exposure system 100 includes a signal light generator 110 and a reference light generator 120. The signal light generator 110 is used to emit signal light to the holographic photosensitive material 001, and the reference light generator 120 is used to emit reference light to the holographic photosensitive material 001. The signal light generator 110 and the reference light generator 120 can share a light source, and the light source is divided into two beams through a beam splitter or the like, and are respectively emitted as signal light and reference light through the signal light generator 110 and the reference light generator 120, or they can each have an independent light source, which are respectively a signal light source and a reference light source. In addition to the light source, the signal light generator 110 can also be configured with a first lens group to shape the light beam emitted by the light source and emit the signal light. The first lens group can shape the light beam emitted by the light source into a parallel beam or a divergent beam. The reference light generator 120 can also be configured with a second lens group to shape the light beam emitted by the light source and emit the reference light. The second lens group can also shape the light beam emitted by the light source into a parallel beam or a divergent beam.

[0037] The first adjustment system 200 includes first adjustment components 210, 220. The first adjustment components can be configured on the optical path of the signal light (such as Figure 4 ), or can be configured on the optical path of the reference light (such as Figure 5 ), or a first adjustment component can be configured on each of the optical paths of the signal light and the reference light (such as Figure 6 ). As shown in Figures 7 - 9As shown, the first adjustment component 210 / 220 is configured with a replaceable aperture 201 located on the optical path. When the signal light or reference light emitted by the exposure system 100 passes through the aperture 201, a part of it passes through the aperture 201 and is incident on the holographic photosensitive material 001, and the other part is blocked by the aperture 201 and cannot be incident on the holographic photosensitive material 001, so as to achieve the purpose of adjusting the light distribution. The first adjustment component 210 / 220 is also configured with a card seat 202 for movably mounting the aperture 201. Thus, the aperture 201 can be machined as an independent part, and the shape and size of the aperture 201 can be customized strictly according to the design drawings, which is beneficial to improving the accuracy of the shape of the aperture 201 and thus significantly improving the exposure quality. When replacing the aperture 201, only need to remove the aperture 201 installed on the card seat 202, and then install a new aperture 201 that meets the light distribution requirements, without the need for tape pasting and cutting, which is beneficial to improving the exposure efficiency.

[0038] The card seat 202 can be configured with a connecting member 2021, a first clamping member 2022 and a second clamping member 2023. The first clamping member 2022 and the second clamping member 2023 are symmetric in structure. The first clamping member 2022 is configured with a first card slot 2024, and the second clamping member 2023 is configured with a second card slot 2025. The first clamping member 2022 and the second clamping member 2023 are symmetrically arranged on the connecting member 2021. The first card slot 2024 and the second card slot 2025 are opposite and spaced apart, and a space for accommodating the aperture 201 is formed between them. The two opposite edges of the aperture 201 are respectively inserted into the first card slot 2024 and the second card slot 2025 to achieve movable installation. The structure of this card seat 202 is simple, which is convenient for the insertion and removal of the aperture 201, provides great convenience and stability for the movable installation of the aperture 201, makes the exposure device more flexible and efficient when adjusting the light distribution, provides a strong guarantee for manufacturing high-quality volume holographic gratings, and at the same time ensures the balance and stability of the aperture 201 during installation, avoiding the deviation or loosening of the aperture 201 caused by improper installation, which is beneficial to ensuring the position accuracy of the aperture 201. The first adjustment component 210 / 220 is also configured with a base 203 for fixing the card seat 202. The base 203 provides a stable support platform for the card seat 202, ensuring the stability of the card seat 202 and the replaceable aperture 201 installed thereon during the exposure process. This stability is crucial for precisely controlling the optical paths of the signal light and the reference light, helping to reduce the exposure errors caused by vibration or displacement, and further improving the stability and consistency of the exposure quality. Specifically, the card seat 202 can be fixedly installed on the base 203 through the connection of its connecting member 2021 with the base 203.

[0039] The grating period d of the volume holographic grating can be decomposed into a surface period and a vertical period. In actual design, generally, the surface period of the grating is first designed as a fixed value, and then the vertical period of the grating is adjusted to obtain a holographic volume grating with different Bragg matching angles or wavelengths, thereby optimizing the performance of the volume holographic grating waveguide. According to the grating formula: nλ = d(sinα - sinβ), when the wavelength λ and the diffraction order are fixed, the incident angle α and the diffraction angle β need to be adjusted to fabricate a volume holographic grating waveguide with a different grating period d. The incident angle α and the diffraction angle β correspond to the incident angle θ1 of the signal light on the volume holographic grating to be exposed and the incident angle θ2 of the reference light on the volume holographic grating to be exposed in the exposure process. These two angles need to be manually changed to fabricate a volume holographic grating with a different grating period d.

[0040] To facilitate the adjustment of the incident angle of the light beam, the exposure device is further provided with an adjustment system 300. The adjustment system 300 includes second adjustment components 310 and 320. The second adjustment components can be arranged on the optical path of the signal light (such as Figure 10 ), or can be arranged on the optical path of the reference light (such as Figure 11 ), or a second adjustment component can be arranged on each of the optical paths of the signal light and the reference light (such as Figure 12 ). As Figures 13 - 15 shown, the second adjustment components 310 / 320 are provided with rotatable mirrors 301 located on the optical path. The signal light or the reference light emitted by the exposure system 100 is incident on the holographic photosensitive material 001 after being reflected by the mirror 301. By rotating the mirror 301 to adjust the angle of the mirror 301, the incident angle of the signal light or the reference light on the holographic photosensitive material 001 can be adjusted, which can significantly shorten the exposure preparation time and improve the production efficiency.

[0041] As Figures 13 - 15As shown, the second adjustment assembly 310 / 320 can also be configured with a rotation mechanism 302. The rotation mechanism 302 is drivingly connected to the mirror 301, driving the mirror 301 to rotate around the rotation center to adjust the incident angles of the signal light or the reference light on the holographic photosensitive material 001. Controlling the rotation of the mirror 301 through the rotation mechanism 302 is beneficial to improving the rotation accuracy of the mirror 301, thereby improving the accuracy of the incident angles θ1 and θ2. Specifically, the rotation mechanism 302 can adopt an electric rotary table, an electric angular position table and other electric rotation mechanisms 302, so as to electrically control the rotation of the mirror 301. This can not only avoid manual adjustment and further improve the efficiency of manufacturing the volume holographic grating, but also enable precise control of the exposure angle, greatly improving the manufacturing accuracy of the volume holographic grating. An electric rotary table is an electric mechanical device that can rotate around a fixed axis. It usually consists of one or more motors, reducers, bearings, turntables and control systems, etc., and can realize continuous or intermittent rotation of an object, with the characteristics of high precision, high speed, large torque and good stability. An electric angular position table (sometimes also called an electric tilt table or angle adjustment table) is a device that can accurately rotate an object within a small angle range. It usually includes a rotatable platform, a motor, a reducer, an angle sensor and a control system, etc., and can realize precise angle adjustment of an object, with the characteristics of high precision, high resolution and fast response.

[0042] As Figures 13 - 14 As shown, the second adjustment assembly 310 / 320 can be configured with a third lens group to enable the light in the optical path where it is located to irradiate the holographic photosensitive material 001 before and after the rotation of the mirror 301 and interfere with the light in the other optical path. The third lens group includes a first lens 303 and a second lens 304. They are located between the mirror 301 and the holographic photosensitive material 001 and are arranged in sequence on the optical path along the propagation direction of the light (signal light or reference light). The optical axes of the first lens 303 and the second lens 304 coincide. The first lens 303 has a first focal point F1, and the second lens 304 has a second focal point F2. The first focal point F1 and the second focal point F2 coincide and are located between the first lens 303 and the second lens 304. The whole formed by the first lens 303 and the second lens 304 has a pair of conjugate points, namely a first base point A1 and a second base point A2. The first base point A1 and the second base point A2 are both located on the optical axis of the first lens 303 and the second lens 304. The first base point A1 is on the side of the first lens 303 facing away from the second lens 304 and coincides with the rotation center O of the mirror 301, and this rotation center is located on the reflecting surface of the mirror 301. The second base point A2 is on the side of the second lens 304 facing away from the first lens 303 and coincides with the holographic photosensitive material 001.

[0043] Therefore, simply by rotating the reflector 301 around the rotation center O by a certain angle, without adjusting the position of the reflector 301, the incident angle of the signal light or reference light on the holographic photosensitive material 001 can be changed. This also ensures that the adjusted signal light or reference light always impinges on the holographic photosensitive material 001 and causes interference. Furthermore, the center of the illuminated area of the holographic photosensitive material 001 always coincides with the second focal point of the second lens 304, significantly improving the efficiency of volume holographic grating production. Through extensive experimentation, a table has been developed that shows the relationship between the grating period and the exposure angle (the angle of the reflector 301). During production, the reflector 301 only needs to be rotated according to the target grating period and this table.

[0044] like Figure 14 As shown, for the case where a second adjustment component is respectively provided on the optical path of the signal light and the reference light, and both second adjustment components adopt the third lens group, the second base point of the second adjustment component 310 located on the optical path of the signal light and the second base point of the second adjustment component 320 located on the optical path of the reference light are preferably coincident, to ensure that the irradiation area of the signal light on the holographic photosensitive material 001 and the irradiation area of the reference light on the holographic photosensitive material 001 overlap each other as much as possible.

[0045] like Figure 15 As shown, the second adjustment assembly 310 / 320 can also be configured with a moving mechanism 305 to ensure that light from its optical path can illuminate the holographic photosensitive material 001 before and after the rotation of the reflector 301, thereby interfering with light from the other optical path. The moving mechanism 305 is in transmission connection with the reflector 301, driving the reflector 301 to move so that the illumination area of the signal light on the holographic photosensitive material 001 substantially overlaps the illumination area of the reference light on the holographic photosensitive material 001. Controlling the movement of the reflector 301 via the moving mechanism 305 helps improve the movement accuracy of the reflector 301. Through extensive experiments, a relationship table between the grating period, the exposure angle (the angle of the reflector 301), and the exposure position (the position of the reflector 301) can be derived. During production, the reflector 301 can be rotated and moved simply according to the target grating period and this relationship table.

[0046] Specifically, the moving mechanism 305 can adopt electric translation stages, electric lifting stages and other electric moving mechanisms 305 to electrically control the rotation and movement of the mirror 301. This can not only avoid manual adjustment, but also enable precise control of the exposure position, improving the production efficiency and accuracy of volume holographic gratings. An electric translation stage is a mechanical device that realizes linear displacement through electric drive. It is usually composed of a motor, a reducer, a transmission mechanism, a guide rail and a platform, etc. It can accurately move a load in a specified direction and has the characteristics of high precision, high stability and large load-bearing capacity. An electric lifting stage is an electric mechanical device that can realize lifting in the vertical direction. It is usually composed of a motor, a reducer, a lifting mechanism, a support structure and a control system, etc. It can carry objects of a certain weight and realize smooth lifting movement, and has the characteristics of large load-bearing capacity, high stability and easy operation.

[0047] For the case where the second adjustment components 310 / 320 control the rotation of the mirror 301 through the rotation mechanism 302 and control the movement of the mirror 301 through the moving mechanism 305, the rotation mechanism 302 and the moving mechanism 305 can be combined into one, and an electric displacement mechanism such as an electric multi-dimensional combination stage integrating rotation and movement functions can be adopted to electrically control the rotation and movement of the mirror 301. This can not only avoid manual adjustment, but also enable precise control of the exposure angle and exposure position, improving the production efficiency and accuracy of volume holographic gratings. An electric multi-dimensional combination stage is a precision device integrating electric drive technology and multi-dimensional movement capabilities, mainly used to realize precise displacement and positioning of multiple axes (such as X, Y, Z axes and possible rotation axes), and has the characteristics of high precision, multi-axis linkage and good stability.

[0048] In contrast, the second adjustment components 310 / 320 using the third lens group do not need to adjust the position of the mirror 301 to ensure that the irradiation area of the light in its optical path before and after adjustment is basically unchanged, and the adjustment efficiency is higher, so the efficiency of manufacturing volume holographic gratings is correspondingly higher; while the second adjustment components 310 / 320 using the moving mechanism 305 need to adjust the position of the mirror 301 to ensure that the light in its optical path overlaps basically with the light in another optical path on the holographic photosensitive material 001. However, for the holographic photosensitive material 001 with a large area and different design periods in each area, the moving mechanism 305 can flexibly adjust the irradiation areas of the signal light and the reference light. During the exposure process, without moving the position of the holographic photosensitive material 001, a volume holographic grating with different grating periods in different areas can be obtained.

[0049] Obviously, the above embodiments of the present solution are merely examples for clearly explaining the present solution, rather than limitations on the implementation manners of the present solution. For those of ordinary skill in the art, other different forms of changes or alterations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present solution shall be included within the protection scope of the claims of the present solution.

Claims

1. An exposure device for exposing a holographic photosensitive material to produce a volume holographic grating, characterized in that: The exposure device includes an exposure system and a first adjustment component. The exposure system is used to emit signal light and reference light to the holographic photosensitive material. The first adjustment component is provided on the optical path of the signal light and / or reference light. The first adjustment component includes a holder and a replaceable aperture located on the optical path. The aperture is a part machined according to the design drawings, movably mounted on the holder for replacement, and is used to adjust the light distribution of the signal light or reference light in the optical path on the holographic photosensitive material.

2. The exposure device according to claim 1, wherein The card holder includes a connecting member, a first clip member and a second clip member, and the first clip member and the second clip member are symmetrically arranged on the connecting member; the first clip member is provided with a first clip slot, and the second clip member is provided with a second clip slot, the first clip slot and the second clip slot are opposite to each other and are arranged at a distance, and a space for accommodating the aperture is formed therebetween, and the two opposite edges of the aperture are respectively inserted into the first clip slot and the second clip slot to achieve movable installation.

3. The exposure device according to claim 2, wherein The first adjustment assembly further includes a base, and the holder is fixedly mounted on the base via a connection between the holder and the base.

4. The exposure device according to claim 1, wherein The first adjustment component also includes a base, and the clamping seat is fixedly installed on the base.

5. The exposure apparatus according to any one of claims 1 to 4, wherein The exposure device also includes a second adjustment component, which is provided on the optical path of the signal light and / or reference light; the second adjustment component includes a rotatable reflector located on the optical path, which is used to adjust the incident angle of the signal light or reference light in the optical path on the holographic photosensitive material.

6. The exposure device according to claim 5, wherein The second adjustment component further includes a rotating mechanism, which is connected to the reflector in a transmission manner and drives the reflector to rotate around a rotation center to adjust the incident angle of the signal light or reference light in the optical path on the holographic photosensitive material.

7. The exposure device according to claim 6, wherein The second adjustment component also includes a first lens and a second lens, which are sequentially arranged on the optical path between the reflector and the holographic photosensitive material, the optical axis of the first lens coincides with the optical axis of the second lens, the first lens has a first focus, the second lens has a second focus, the first focus and the second focus coincide and are located between the first lens and the second lens, the first lens and the second lens have a first base point and a second base point, the first base point and the second base point are conjugate and are both located on the optical axis, the first base point is located on the side of the first lens facing away from the second lens, and coincides with the rotation center of the reflector, the rotation center is located on the reflection surface of the reflector, the second base point is located on the side of the second lens facing away from the first lens, and coincides with the holographic photosensitive material.

8. The exposure device according to claim 7, wherein The second adjustment component is provided on the optical paths of both the signal light and the reference light, and the second base points of the adjustment components located on the signal light optical path coincide with the second base points of the adjustment components located on the reference light optical path.

9. The exposure device according to claim 6, wherein the second adjustment component further includes a displacement mechanism, and the displacement mechanism is drivingly connected to the mirror to drive the mirror to move so that the irradiation area of the signal light on the holographic photosensitive material substantially overlaps with the irradiation area of the reference light on the holographic photosensitive material.

10. The exposure device according to claim 5, wherein the second adjustment component further includes a rotation and translation mechanism, and the rotation and translation mechanism is drivingly connected to the mirror to drive the mirror to rotate about its rotation center to adjust the incident angle of the signal light or the reference light on the holographic photosensitive material in the optical path where it is located, and to drive the mirror to move so that the irradiation area of the signal light on the holographic photosensitive material substantially overlaps with the irradiation area of the reference light on the holographic photosensitive material.

Images