Manufacturing device of volume holographic curved waveguide

Abstract

The utility model discloses a manufacturing device of a volume holographic curved waveguide. The device comprises a reference light generator and a signal light generator which are used for interfering and exposing a holographic photosensitive material layer positioned in a coupling-out region and / or a transition region, so that the holographic photosensitive material layer forms a volume holographic grating layer. The reference light generator is used for generating single-pixel reference light corresponding to the ith pixel, the single-pixel reference light is coupled into the curved waveguide layer and then is subjected to total reflection propagation in the curved waveguide layer, and the holographic photosensitive material layer is irradiated in the total reflection propagation process. The signal light generator is used for generating single-pixel signal light corresponding to the ith pixel, and the single-pixel signal light is directly emitted on the holographic photosensitive material layer. The single-pixel reference light and the single-pixel signal light interfere with each other on the holographic photosensitive material layer, and interference fringes are recorded by the holographic photosensitive material layer.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical waveguides, and specifically relates to a device for manufacturing a volume holographic curved waveguide. Background Art

[0002] The optical display system of AR devices is usually composed of micro-displays and optical components. In general, the display system used by AR glasses on the market is a combination of various micro-displays and optical components such as prisms, free-form surfaces, BirdBath, and optical waveguides. The difference in optical combiners is the key part to distinguish AR display systems. At present, the optical waveguide solution has the best development potential in terms of optical effects, appearance and mass production prospects.

[0003] Optical waveguides can be generally divided into two types: geometric optical waveguides and diffractive optical waveguides. Geometric optical waveguides are so-called array optical waveguides, which achieve image output and eye box expansion through stacking array reflectors. Diffractive optical waveguides mainly include surface relief grating waveguides made using photolithography technology and volume holographic grating waveguides made based on holographic interference technology. However, due to the difficulties in the process and production of geometric optical waveguides, if AR glasses want to have the appearance of ordinary glasses and truly enter the consumer market, diffractive optical waveguides are currently the only choice.

[0004] The optical waveguide technology for AR glasses that has been developed and mass-produced is planar waveguide, but AR glasses made of planar waveguide are not suitable for people with myopia and hyperopia, resulting in a very poor experience for people with myopia and hyperopia when using such AR glasses. They need to add AR glasses in addition to prescription glasses to realize the function of augmented reality display. This increases the overall weight and size of the glasses worn by the wearer, resulting in low public acceptance of AR glasses and limiting the consumer-level popularity of AR glasses.

[0005] The reason why it is difficult to realize a curved waveguide for a volume holographic grating waveguide is that the volume holographic grating is formed by interference exposure of a holographic material, and the holographic material is required to have a flat surface during exposure. Therefore, the prior art usually forms a holographic film with a volume holographic grating on a plane by interference exposure, and then transfers and bonds it to a curved waveguide. Utility Model Content

[0006] The present invention aims to overcome at least one defect in the prior art and provide a volume holographic curved waveguide manufacturing device which can directly record and form a volume holographic grating on a curved waveguide.

[0007] In order to solve the above technical problems, the following technical solutions are adopted:

[0008] In a first aspect, a method for manufacturing a volume holographic curved waveguide is provided. The method comprises the following exposure steps for interferometrically exposing a holographic photosensitive material layer located in an outcoupling region and / or a turning region:

[0009] According to the pixel distribution of the virtual image, the reference light is adjusted to a single-pixel reference light corresponding to the i-th pixel, and the signal light is adjusted to a single-pixel signal light corresponding to the i-th pixel;

[0010] The single-pixel reference light is coupled into the curved waveguide layer, so that it is totally reflected and propagated inside the curved waveguide layer, and the holographic photosensitive material layer is irradiated during the totally reflected propagation process. Meanwhile, the single-pixel signal light is directly emitted onto the holographic photosensitive material layer, and the single-pixel reference light and the single-pixel signal light interfere with each other on the holographic photosensitive material layer, and the holographic photosensitive material layer records the interference fringes corresponding to the i-th pixel;

[0011] Let i=i+1, and repeat the above steps until the holographic photosensitive material layer records the interference fringes corresponding to all pixels, thus forming a volume holographic grating layer.

[0012] This scheme adjusts the reference light and signal light to single-pixel reference light and single-pixel signal light respectively based on the pixel distribution of the virtual image, and exposes the holographic photosensitive material layer multiple times by using the single-pixel reference light and single-pixel signal light. The virtual image is exposed as many times as the number of pixels it contains. Each exposure forms only a single-pixel volume holographic grating corresponding to a certain pixel, and multiple exposures form multiple single-pixel volume holographic gratings corresponding to different pixels. The single-pixel volume holographic grating corresponding to the i-th pixel only diffracts the projection light beam corresponding to the i-th pixel, and does not diffract the projection light beams corresponding to other pixels, so that the transmission and coupling of light of different wavelengths (different colors) in the resulting volume holographic curved waveguide will not interfere with each other. At the same time, this scheme also transmits the single-pixel reference light by total reflection propagation, which is conducive to avoiding stray light and thus avoiding the influence on the interference fringes. Therefore, through the synergistic effect of single-pixel illumination and total reflection propagation, it is possible to directly expose the volume holographic grating layer on the curved waveguide layer.

[0013] Since the exposure process is to expose the holographic photosensitive material layer one by one through single-pixel reference light and single-pixel signal light to form a single-pixel volume holographic grating corresponding to each pixel, the resulting volume holographic grating layer will specifically diffract the transmission light of each pixel, making them emit as concentric light beams to facilitate imaging.

[0014] Before the exposure step, the method further includes a pre-processing step: customizing prescription eyeglasses as the curved waveguide layer according to the eye parameters of the wearer. Whether it is a general population or a special population such as myopia or hyperopia, the curved waveguide layer can use prescription eyeglasses customized according to the eye parameters of the wearer to make the visual effect clearer and more comfortable, and the eyes more relaxed, so as to avoid visual fatigue and other problems.

[0015] Before the exposure step, the method further comprises a pre-treatment step: disposing a holographic photosensitive material layer on the surface or inside the curved waveguide layer. The holographic photosensitive material layer is formed of a holographic photosensitive material that is sensitive to the reference light and the signal light. The holographic photosensitive material can be coated on the surface of the curved waveguide layer by spin coating, spray coating, or the like, or filled inside the curved waveguide layer by injection, thereby forming a holographic photosensitive material layer disposed on the curved waveguide layer.

[0016] In a second aspect, a device for making a volume holographic curved waveguide is provided, which includes a reference light generator and a signal light generator, and is used for interferometrically exposing a holographic photosensitive material layer located in an outcoupling region and / or a turning region to form a volume holographic grating layer.

[0017] The reference light generator is used to generate a single-pixel reference light corresponding to the i-th pixel. After the single-pixel reference light is coupled into the curved waveguide layer, it is totally reflected and propagated inside the curved waveguide layer, and irradiates the holographic photosensitive material layer during the total reflection propagation process. The signal light generator is used to generate a single-pixel signal light corresponding to the i-th pixel. The single-pixel signal light is directly emitted on the holographic photosensitive material layer. The single-pixel reference light and the single-pixel signal light interfere with each other on the holographic photosensitive material layer, and their interference fringes are recorded by the holographic photosensitive material layer.

[0018] In this scheme, a single-pixel reference light corresponding to the i-th pixel is generated by a reference light generator to illuminate the holographic photosensitive material layer, and a single-pixel signal light corresponding to the i-th pixel is generated by a signal light generator to illuminate the holographic photosensitive material layer, so that the interference fringes recorded by the holographic photosensitive material layer and the formed single-pixel volume holographic grating only diffract the projection light beam corresponding to the i-th pixel, and do not diffract the projection light beams corresponding to other pixels, so that the transmission and coupling of light of different wavelengths (different colors) in the resulting volume holographic curved waveguide will not interfere with each other. The single-pixel reference light generated by the reference light generator is irradiated to the holographic photosensitive material layer through total reflection propagation in the curved waveguide layer, which is conducive to avoiding stray light to avoid affecting the interference fringes. Therefore, through the synergistic effect of single-pixel irradiation and total reflection propagation, it is possible to directly expose and form a volume holographic grating layer on the curved waveguide layer.

[0019] Since the exposure process is to expose the holographic photosensitive material layer one by one through single-pixel reference light and single-pixel signal light to form a single-pixel volume holographic grating corresponding to each pixel, the resulting volume holographic grating layer will specifically diffract the transmission light of each pixel, making them emit as concentric light beams to facilitate imaging.

[0020] The reference light generator includes a reference light source, a first spatial light modulator and a first lens group. The reference light source generates reference light and emits it to the first spatial light modulator. The first spatial light modulator modulates the reference light into a first point light source of a single pixel corresponding to the i-th pixel and emits it to the first lens group. The first lens group shapes the first point light source and emits it as the above-mentioned single-pixel reference light. The first lens group can shape the first point light source into a parallel light beam or a divergent light beam. In other words, the single-pixel reference light emitted by the first lens group can be a parallel light beam or a divergent light beam, which has no effect on the reproduction of the virtual image.

[0021] The signal light generator includes a signal light source, a second spatial light modulator and a second lens group. The signal light source generates signal light and emits it to the second spatial light modulator. The second spatial light modulator modulates the signal light into a second point light source of a single pixel corresponding to the i-th pixel and emits it to the second lens group. The second lens group shapes the second point light source and emits it as the above-mentioned single-pixel signal light. The second lens group can shape the second point light source into a parallel light beam or a divergent light beam. If the single-pixel signal light is a parallel light beam, the virtual image reproduced by the resulting volume holographic curved waveguide is at infinity. If the single-pixel signal light is a divergent light beam, the virtual image reproduced by the resulting volume holographic curved waveguide is at a finite distance, and the distance from the virtual image to the volume holographic curved waveguide can be adjusted by adjusting at least two of the focal length of the second lens group, the distance between the second lens group and the second spatial light modulator, and the distance between the second lens group and the holographic photosensitive material layer. The distance between the second lens group and the second spatial light modulator, and the distance between the second lens group and the holographic photosensitive material layer can be adjusted specifically by moving the second lens group, the second spatial light modulator, and the volume holographic curved waveguide, thereby producing volume holographic curved waveguides with different virtual image distances, so that the virtual image distance can also be adapted to people with different vision.

[0022] The above-mentioned device may also include at least two of a first moving mechanism, a second moving mechanism, and a third moving mechanism. The signal light source and the second spatial light modulator are mounted on the first moving mechanism, and the position of the second spatial light modulator can be adjusted by the first moving mechanism, thereby adjusting the distance between the second lens group and the second spatial light modulator; the second lens group is mounted on the second moving mechanism, and the position of the second lens group can be adjusted by the second moving mechanism, thereby adjusting the distance between the second lens group and the second spatial light modulator and the distance between the second lens group and the holographic photosensitive material layer; the volume holographic curved waveguide is mounted on the third moving mechanism, and the position of the volume holographic curved waveguide can be adjusted by the third moving mechanism, thereby adjusting the distance between the second lens group and the holographic photosensitive material layer, so as to adjust the distance of the finite distance virtual image.

[0023] The above device may further include an object stage for mounting and positioning the volume holographic curved waveguide to be exposed. The object stage may be mounted on a third moving mechanism so that the position of the object stage can be adjusted by the third moving mechanism, that is, the distance from the second lens group to the holographic photosensitive material layer can be adjusted, thereby adjusting the distance of the finite distance virtual image.

[0024] The above-mentioned device may also include a coupler to couple the single-pixel reference light into the curved waveguide layer. The coupler includes a coupling grating, which may be a volume holographic grating or a surface relief grating, and may be fixedly mounted on the surface of the volume holographic curved waveguide to be exposed by bonding or the like. In addition, the single-pixel reference light may also be coupled into the curved waveguide layer through the coupling grating provided by the volume holographic curved waveguide, and the coupling grating may be a volume holographic grating or a surface relief grating, and may be fixed in the volume holographic curved waveguide by bonding or the like. If the coupling grating provided by the volume holographic curved waveguide is a volume holographic grating, the coupling grating may also be a part of the volume holographic grating layer, and may be exposed and formed on the curved waveguide layer.

[0025] The above-mentioned device may also include a box having a cavity, in which the above-mentioned reference light generator, signal light generator, stage and other devices are installed, which is convenient for assembly and positioning of the devices and helps to create an environment suitable for exposure.

[0026] In a third aspect, a volume holographic curved waveguide is provided. The volume holographic curved waveguide is made by the above method or device, and comprises a curved waveguide layer and a volume holographic grating layer, wherein the volume holographic grating layer is located on the surface or inside of the curved waveguide layer and at least covers the outcoupling region and / or the turning region.

[0027] This solution realizes total reflection propagation of light through a curved waveguide layer with at least one curved surface, so that the volume holographic curved waveguide can better adapt to the curvature of the eye itself and fit the surface of the eye more closely, thereby eliminating visual distortion. When light passes through the volume holographic curved waveguide, it can better match the physiological structure of the eye, improving visual clarity and comfort. The surface parameters of the curved waveguide layer can be precisely customized according to personal eye characteristics and vision data. The customized curved waveguide layer is equivalent to a prescription lens, which has a refractive power and adapts to the wearer's vision. When applied to AR and other head-mounted display products, it is not necessary to wear prescription glasses to clearly see the real environment through the volume holographic curved waveguide, reducing the overall weight and size that the wearer needs to bear when wearing the head-mounted display product, and improving the public's acceptance of the head-mounted display product.

[0028] The volume holographic grating layer in the out-coupling area and / or the turning area is exposed by the above method or device. Since the exposure process is to expose the holographic photosensitive material layer one by one by single-pixel reference light and single-pixel signal light to form a single-pixel volume holographic grating corresponding to each pixel, the volume holographic grating layer obtained will specifically diffract the transmission light of each pixel, so that the transmission and out-coupling of light of different wavelengths (different colors) in the obtained volume holographic curved waveguide will not interfere with each other, and they are emitted as concentric light beams to facilitate imaging.

[0029] The volume holographic grating layer also covers the coupling-in region. The volume holographic grating layer in the coupling-in region can be formed first and then mounted on the curved waveguide layer, or can be formed by directly exposing on the curved waveguide layer using a conventional exposure method.

[0030] In a fourth aspect, a head-mounted display product is provided. The head-mounted display product includes a projection optical machine and a volume holographic curved waveguide. The volume holographic curved waveguide is made by the above method or device, includes a curved waveguide layer and a volume holographic grating layer, and is provided with an incoupling region and an outcoupling region. The volume holographic grating layer is located on the surface or inside of the curved waveguide layer, and at least covers the outcoupling region.

[0031] The projection optical machine is similar to a projector, projecting light with virtual images from the coupling-in area of ​​the volume holographic curved waveguide into the volume holographic curved waveguide. The coupling-in area of ​​the volume holographic curved waveguide couples the light beam from the projection optical machine into the waveguide, so that the light beam can be fully reflected and propagated inside the curved waveguide layer. Since the exposure process of the coupling-out area is to expose the holographic photosensitive material layer one by one through single-pixel reference light and single-pixel signal light, the resulting volume holographic grating layer will perform specific diffraction on the transmission light of each pixel, so that the transmission and coupling of light beams of different wavelengths (different colors) in the resulting volume holographic curved waveguide will not interfere with each other, and make them emerge as concentric light beams for easy imaging.

[0032] Moreover, at least one side of the curved waveguide layer is a curved surface, which can better adapt to the curvature of the eye itself and fit the surface of the eye more closely, thereby eliminating visual distortion. When light passes through the volume holographic curved waveguide, it can better match the physiological structure of the eye, improving visual clarity and comfort. The curved parameters of the curved waveguide layer can be precisely customized according to individual eye characteristics and vision data. The customized curved waveguide layer is equivalent to a prescription lens, which has a refractive power and adapts to the wearer's vision. When applied to AR and other head-mounted display products, it is not necessary to wear prescription glasses to clearly see the real environment through the volume holographic curved waveguide, reducing the overall weight and size that the wearer needs to bear when wearing the head-mounted display product, and improving the public's acceptance of the head-mounted display product.

[0033] The volume holographic grating layer can also cover the coupling-in region. The volume holographic grating layer in the coupling-in region can be formed first and then mounted on the curved waveguide layer, or can be formed by directly exposing on the curved waveguide layer using a conventional exposure method.

[0034] The volume holographic curved waveguide can also be provided with a turning zone. The volume holographic grating layer can also cover the turning zone. The volume holographic grating layer in the coupling zone can be formed first and then installed on the curved waveguide layer, or it can be formed by directly exposing on the curved waveguide layer using the above method or device.

[0035] Compared with the prior art, this solution has the following beneficial effects: This solution innovatively proposes a device for directly exposing a volume holographic grating layer on a curved substrate. The volume holographic curved waveguide produced by the device can be customized according to the wearer's vision, thereby improving the public's acceptance of head-mounted display products. In addition, the transmission light of each pixel will be specifically diffracted so that they are emitted as concentric light beams for easy imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings are only used for illustrative purposes and should not be construed as limitations on the present invention. In order to better illustrate the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. The light in the drawings only indicates the general direction of light propagation, not a specific light ray, and is not intended to limit the number of light rays, propagation paths, angles, etc. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0037] Figure 1 This is a schematic diagram of the possible structure of a head-mounted display product.

[0038] Figure 2 This is a schematic diagram of the possible structure of volume holographic curved waveguide.

[0039] Figure 3 It is a flow chart of the method for manufacturing volume holographic curved waveguide.

[0040] Figure 4 It is a schematic diagram of the structure and exposure of a volume holographic curved waveguide manufacturing device.

[0041] Figure 5 Is adopted Figure 4 Schematic diagram of imaging of volume holographic curved waveguide made by the device shown.

[0042] Figure 6 It is an exposure schematic diagram of a volume holographic curved waveguide manufacturing device in which the signal light is a parallel beam.

[0043] Figure 7 Is adopted Figure 6 Schematic diagram of imaging of volume holographic curved waveguide made by the device shown.

[0044] Figure 8 It is a schematic diagram of the structure of a volume holographic curved waveguide manufacturing device in which both the signal light and the reference light are parallel beams.

[0045] Fig. 9 It is a structural schematic diagram of a volume holographic curved waveguide manufacturing device in which the signal light is a parallel beam and the reference light is a divergent beam.

[0046] Fig.10 It is an exposure schematic diagram of a volume holographic curved waveguide manufacturing device in which the signal light is a divergent beam.

[0047] Fig.11 Is adopted Fig.10 Schematic diagram of imaging of volume holographic curved waveguide made by the device shown.

[0048] Fig.12 It is a structural schematic diagram of a volume holographic curved waveguide manufacturing device in which the signal light is a divergent beam and the reference light is a parallel beam.

[0049] Fig.13 It is a schematic diagram of the structure of a volume holographic curved waveguide manufacturing device in which both the signal light and the reference light are divergent beams.

[0050] Description of reference numerals: projection optical machine 100, volume holographic curved waveguide 200, curved waveguide layer 210, first surface 211, second surface 212, volume holographic grating layer 220, holographic photosensitive material layer 221, coupling grating 300, reference light generator 410, reference light source 411, first spatial light modulator 412, first lens group 413, signal light generator 420, signal light source 421, second spatial light modulator 422, second lens group 423, projection light beam 101, reproduced signal light 201, reverse extension line 201' of reproduced signal light, reference light 4011, first point light source 4012, single-pixel reference light 4013, signal light 4021, second point light source 4022, single-pixel signal light 4023, virtual image I’ , human eye E’ . DETAILED DESCRIPTION

[0051] In order to enable those skilled in the art to better understand the present solution, the present solution is further described in detail below in conjunction with specific embodiments.

[0052] Figure 1 This shows possible head-mounted display products. Figure 1As shown, the head display product includes a projection optical machine 100 and a volume holographic curved waveguide 200. The projection optical machine 100 is similar to a projector, and projects light with a virtual image into the volume holographic curved waveguide 200. The volume holographic curved waveguide 200 transmits and couples the light from the projection optical machine 100, and the coupled light enters the human eye to form a virtual image, realizing different effects such as virtual reality (VR), augmented reality (AR), and mixed reality (MR). According to different effects, head display products can be divided into different types. Among them, VR head display products are the carriers of virtual reality technology. Through computer technology, a three-dimensional virtual world that allows the wearer to interact with it is generated, so that the wearer has an immersive feeling. AR head display products are the carriers of augmented realization technology. Through computer technology, virtual information is applied to the real world, so that the real environment and virtual objects are superimposed on the same screen or space in real time and exist simultaneously. MR head display products are the carriers of mixed reality technology, combining the characteristics of VR and AR, allowing the wearer to interact with real and virtual environments.

[0053] The head display product can be designed as an eye mask structure or a glasses structure. For the former, the volume holographic curved waveguide 200 is set as a single piece, and the projection optical machine 100 can be set in the middle of the volume holographic curved waveguide 200, or on the left or right side of the volume holographic curved waveguide 200, or one projection optical machine 100 can be set on the left and right sides of the volume holographic curved waveguide 200. For the latter, the volume holographic curved waveguide 200 is set as a double piece, and the projection optical machine 100 can be set between the two pieces of volume holographic curved waveguides 200, or on the left side of the left volume holographic curved waveguide 200 or on the right side of the right volume holographic curved waveguide 200, or one projection optical machine 100 can be set on the left side of the left volume holographic curved waveguide 200 and on the right side of the right volume holographic curved waveguide 200.

[0054] The head-mounted display product usually also includes a bracket. The bracket is used to install and fix the projection optical machine 100 and the volume holographic curved waveguide 200, so that the relative positions of the projection optical machine 100 and the volume holographic curved waveguide 200 are fixed, and is also used to achieve wearing, so that the volume holographic curved waveguide 200 is directly in front of the human eye when the wearer wears the head-mounted display product. For head-mounted display products with a glasses-like structure, the bracket includes a frame and temples. The temples can be rotatably connected to the frame. After the temples are rotated in a direction close to the frame, they form a folded state to facilitate the storage of the head-mounted display product. After the temples are rotated in a direction away from the frame, they form an unfolded state so that the head-mounted display product can be worn on the wearer's head. The volume holographic curved waveguide 200 is installed in the frame as a lens, so that the wearer can see the above-mentioned virtual image through the volume holographic curved waveguide 200.

[0055] The human eye is not flat, and the cornea, lens and other parts have a certain curvature. Compared with a planar waveguide, the curved volume holographic curved waveguide 200 can better adapt to the curvature of the eye itself and fit the surface of the eye more closely, thereby eliminating visual distortion. When light passes through the volume holographic curved waveguide 200, it can better match the physiological structure of the eye, improving visual clarity and comfort. The curved surface of the volume holographic curved waveguide 200 can be precisely customized according to personal eye characteristics and vision data, so that the curvature of the volume holographic curved waveguide 200 is more suitable for the shape of the wearer's eyeball, making the visual effect clearer and more comfortable, making the eyes more relaxed, and avoiding problems such as visual fatigue caused by head-mounted display products. In this way, people with vision problems such as myopia and hyperopia can clearly see the virtual images projected by the head-mounted display product without wearing prescription glasses when wearing the head-mounted display product. They can also clearly see the real environment through the volume holographic curved waveguide 200 without wearing prescription glasses when wearing AR or MR head-mounted display products, thereby reducing the overall weight and size that the wearer needs to bear when wearing the head-mounted display product, and improving the public's acceptance of the head-mounted display product.

[0056] Figure 2 A possible volume holographic curved waveguide 200 is shown. Figure 2 As shown, the volume holographic curved waveguide 200 includes a curved waveguide layer 210 and a volume holographic grating layer 220. The curved waveguide layer 210 is a layered structure, having a first surface 211 and a second surface 212 opposite to each other. The light coupled into the volume holographic curved waveguide 200 can be totally reflected and propagated between the first surface 211 and the second surface 212. At least one of the first surface 211 and the second surface 212 is a curved surface to match the physiological structure of the human eye and improve the visual clarity and comfort. The parameters of the curved surface can be precisely customized according to personal eye characteristics and vision data. The customized curved waveguide layer 210 is equivalent to a prescription eyeglass, which has a refractive power and is adapted to the wearer's vision. The volume holographic grating layer 220 is also a layered structure and can be set at multiple positions of the curved waveguide layer 210, specifically, it can be set at the first surface 211 of the curved waveguide layer 210, it can also be set at the second surface 212 of the curved waveguide layer 210, and it can also be set inside the curved waveguide layer 210 between the first surface 211 and the second surface 212.

[0057] The waveguide is usually provided with two functional areas, namely, an in-coupling area and an out-coupling area, and some waveguides are also provided with a turning area. The in-coupling area is used to couple the light beam from the projection optical machine 100 into the waveguide, so that the light beam can be totally reflected and propagated inside the waveguide, thereby realizing the in-coupling function. The turning area is used to change the propagation direction of the light beam from the in-coupling area in the waveguide, and to expand the range of the light beam, thereby realizing the turning function. If the waveguide is not provided with a turning area, the out-coupling area is used to expand the range of the light beam from the in-coupling area and couple the light beam out of the waveguide. If the waveguide is provided with a turning area, the out-coupling area is used to expand the range of the light beam from the turning area and couple the light beam out of the waveguide, thereby realizing the out-coupling function. The functions of in-coupling, out-coupling, and turning are usually realized by gratings. The grating that realizes the in-coupling function can be called an in-coupling grating, the grating that realizes the out-coupling function can be called an out-coupling grating, and the grating that realizes the turning function can be called a turning grating.

[0058] In the volume holographic curved waveguide 200, the volume holographic grating layer 220 is at least used to realize the outcoupling or turning function, and accordingly, it at least covers the outcoupling region or the turning region of the volume holographic curved waveguide 200. That is, the volume holographic grating layer 220 can only cover the outcoupling region or only cover the turning region, or cover the turning region and the outcoupling region, cover the incoupling region and the outcoupling region, or cover the incoupling region and the turning region, and can also cover the incoupling region, the turning region, and the outcoupling region to realize the corresponding function. In other words, the volume holographic grating layer 220 can be an outcoupling grating or a turning grating, or a collection of an outcoupling grating and a turning grating, or a collection of an outcoupling grating and / or a turning grating and an incoupling grating. The corresponding functions of the incoupling region, the turning region, or the outcoupling region not covered by the volume holographic grating layer 220 can be realized by using other types of gratings such as surface relief gratings, wherein the turning region can also be eliminated. Of course, the coupling-in function, coupling-out function, and even the turning function of the volume holographic curved waveguide 200 are preferably implemented by the volume holographic grating layer 220. The volume holographic grating layer 220 covering different functional areas can be the same volume holographic grating layer 220, or different volume holographic grating layers 220. Different volume holographic grating layers 220 can be stacked and arranged at the same position of the curved waveguide layer 210, or can be arranged at different positions of the curved waveguide layer 210, such as the first surface 211, the second surface 212, or between the first surface 211 and the second surface 212.

[0059] The predecessor of the volume holographic grating layer 220 is a holographic photosensitive material layer. When the reference light and the signal light from different directions interfere with each other in the holographic photosensitive material layer, the interference fringes will be recorded in the holographic photosensitive material layer to form the volume holographic grating layer 220. When the light beam emitted by the projection optical machine 100 passes through the volume holographic grating layer 220, diffraction will occur, thereby realizing the functions of coupling in, coupling out, and turning.

[0060] Figure 3The method for manufacturing the volume holographic curved waveguide 200 is illustrated. The method can directly expose the holographic photosensitive material layer on the curved waveguide layer 210, specifically, can expose to form a volume holographic grating layer 220 for outcoupling, can also expose to form a volume holographic grating layer 220 for turning, can also expose to form a volume holographic grating layer 220 for turning and outcoupling. Figure 3 As shown, the method may include the following exposure steps.

[0061] Step S311: According to the pixel distribution of the virtual image, the reference light is adjusted to be a single-pixel reference light corresponding to the i-th pixel, and the signal light is adjusted to be a single-pixel signal light corresponding to the i-th pixel.

[0062] The virtual image emitted by the projection optical machine 100 includes multiple pixels, and the light corresponding to each pixel is transmitted differently in the volume holographic curved waveguide 200. Based on the pixel distribution of the virtual image, the reference light is adjusted to the single-pixel reference light corresponding to the i-th pixel, and the signal light is adjusted to the single-pixel signal light corresponding to the i-th pixel, so that the single-pixel volume holographic grating formed by the interference of the single-pixel reference light and the single-pixel signal light can only be illuminated by the projection light beam corresponding to the i-th pixel, and will not reproduce the signal light when illuminated by the projection light beam corresponding to other pixels, so it will not be illuminated. Compared with the multi-pixel volume holographic grating formed by the interference of multi-pixel reference light and multi-pixel signal light, the single-pixel volume holographic grating only diffracts the projection light beam of a single specific pixel. Even if the surface period of the single-pixel volume holographic grating is inconsistent at various locations, crosstalk will not be generated. The volume holographic grating layer composed of multiple single-pixel volume holographic gratings can ensure the transmission of full-color effects.

[0063] The virtual image emitted by the projection optical machine 100 includes multiple pixels. The position of the light corresponding to each pixel emitted to the volume holographic curved waveguide 200 is different, the transmission conditions in the volume holographic curved waveguide 200 are different, and the position of coupling out from the volume holographic curved waveguide 200 and entering the human eye is also different. Based on the pixel distribution of the virtual image, the reference light is adjusted to a single-pixel reference light corresponding to the i-th pixel, so that the single-pixel reference light is bound to illuminate the position corresponding to the i-th pixel in the holographic photosensitive material layer. The signal light is adjusted to a single-pixel signal light corresponding to the i-th pixel, so that the single-pixel signal light only illuminates the position corresponding to the i-th pixel in the holographic photosensitive material layer, and only interferes with the single-pixel reference light that also illuminates the position, avoiding interference with the reflected light of the reference light, and ensuring that the surface period of each part of the volume holographic grating layer 220 is the same.

[0064] Step S312: couple the single-pixel reference light into the curved waveguide layer, so that it is totally reflected and propagated inside the curved waveguide layer, and irradiates the holographic photosensitive material layer during the totally reflected propagation process. At the same time, the single-pixel signal light is directly emitted onto the holographic photosensitive material layer, and the single-pixel reference light and the single-pixel signal light interfere with each other on the holographic photosensitive material layer, and the holographic photosensitive material layer records the interference fringes corresponding to the i-th pixel.

[0065] The single pixel reference light can be coupled into the curved waveguide layer 210 through a coupling grating pre-set on the curved waveguide layer 210. The coupling grating can be set in the coupling region of the curved waveguide layer 210, and can also be used as a part of the final product to couple the light from the projection optical machine 100 into the curved waveguide layer 210, so that the light can be totally reflected and propagated between the first surface 211 and the second surface 212 of the curved waveguide layer 210. The coupling grating can be a volume holographic grating or a surface relief grating. Whether it is a volume holographic grating or a surface relief grating, the coupling grating can be formed first and then installed on the curved waveguide layer 210. For the volume holographic grating, since the incident angle of the light projected by the projection optical machine 100 into the volume holographic curved waveguide 200 is generally small, correspondingly, the incident angle of the reference light used for exposure to form the coupling grating is also small, and it is not easy to reflect light and cause the influence on the interference fringes. Therefore, the conventional exposure method can be used to directly expose the coupling region of the curved waveguide layer 210 to form the coupling grating. The single-pixel reference light coupled into the curved waveguide layer 210 will be fully reflected and propagated inside the curved waveguide layer 210, and will irradiate the holographic photosensitive material layer during the process of total reflection and propagation, which is conducive to avoiding stray light and thus avoiding the influence on the interference fringes.

[0066] The single-pixel signal light can be emitted from one side of the curved waveguide layer 210 toward the curved waveguide layer 210. The surface 211 of the curved waveguide layer 210 facing the single-pixel signal light can be called the front surface, and the surface 212 facing away from the single-pixel signal light can be called the back surface. The single-pixel signal light can directly irradiate the holographic photosensitive material layer located on the front surface of the curved waveguide layer 210, or can directly pass through the curved waveguide layer 210 to irradiate the holographic photosensitive material layer located inside or on the back surface of the curved waveguide layer 210. The single-pixel signal light and the single-pixel reference light superimposed on the holographic photosensitive material layer will interfere at the position corresponding to the pixel, and the holographic photosensitive material layer will record the wavefront information of the single-pixel signal light and the single-pixel reference light as well as the spatial distribution of the interference fringes to form a volume holographic grating.

[0067] Step S313 : let i=i+1, and repeat steps S311 - S312 until the holographic photosensitive material layer records the interference fringes corresponding to all pixels, thereby forming a volume holographic grating layer 220 .

[0068] The interference of the single-pixel reference light and the single-pixel signal light corresponding to the i-th pixel can only form a single-pixel volume holographic grating corresponding to the i-th pixel, and the single-pixel volume holographic grating only diffracts the projection light beam corresponding to the i-th pixel. Only by allowing the holographic photosensitive material layer to record the interference fringes corresponding to each pixel and forming a single-pixel volume holographic grating corresponding to each pixel can it be ensured that each pixel of the virtual image can be presented. According to steps S311~S312, each pixel of the virtual image is exposed one by one, and each exposure only records the interference fringes corresponding to one pixel. The number of exposures is the same as the number of pixels. Assuming that the virtual image contains m×n pixels, it must be exposed m×n times until the interference fringes corresponding to all pixels are recorded, and the final volume holographic grating layer 220 is formed.

[0069] The volume holographic grating layer 220 formed by exposure using the above method will perform specific diffraction on the transmission light of each pixel, which can not only avoid crosstalk between lights of different wavelengths, but also make them emerge as concentric light beams, which is conducive to imaging. During the imaging process, the light emitted by the projection optical machine 100 will be coupled into the volume holographic curved waveguide 200 along the direction of the reference light during exposure, and will be propagated by total reflection in the curved waveguide layer 210. When it propagates to the volume holographic grating layer 220 in the turning area, the propagation direction will be changed according to the diffraction principle. When it propagates to the volume holographic grating layer 220 in the outcoupling area, the information of the signal light will be reproduced according to the diffraction principle. Since the volume holographic grating layer 220 records all the pixels of the virtual image, all the pixels of the virtual image will be reproduced during reproduction to form a virtual image, and the human eye can see this virtual image through this volume holographic curved waveguide 200. For the outcoupling region, if the signal light during exposure is a parallel beam, the reproduced signal light is also a parallel beam, and the human eye will see an infinitely distant virtual image on the volume holographic curved waveguide 200, such as Figure 7 If the signal light during exposure is a divergent beam, the reproduced signal light is also a divergent beam, and the human eye will see a virtual image of finite distance on the volume holographic curved waveguide 200, such as Figure 8 , the distance of the virtual image can be adjusted, and the adjustment method will be described in detail below.

[0070] In addition, the method may further include the following pre-processing steps, which need to be performed before exposure.

[0071] S301: Customizing a prescription eyeglass lens as a curved waveguide layer according to eye parameters of the wearer.

[0072] Whether it is the general population or special populations such as myopia and hyperopia, the curved waveguide layer 210 can use prescription eyeglasses customized according to the wearer's eye parameters to make the visual effect clearer and more comfortable, and the eyes more relaxed, so as to avoid visual fatigue and other problems. For the general population, the curved waveguide layer 210 can also use universal eyeglasses to improve production efficiency and reduce production costs.

[0073] S302: Disposing a holographic photosensitive material layer on the curved waveguide layer.

[0074] The holographic photosensitive material layer is formed of a holographic photosensitive material that is sensitive to the reference light and the signal light. The holographic photosensitive material can be coated on the surface of the curved waveguide layer 210, i.e., the first surface 211 or the second surface 212, by spin coating, spray coating, or the like, or can be filled into the interior of the curved waveguide layer 210, i.e., between the first surface 211 and the second surface 212, by injection to form a holographic photosensitive material layer disposed on the curved waveguide layer 210.

[0075] Figures 4 to 13 The device for manufacturing the above-mentioned volume holographic curved waveguide 200 and the imaging optical path of the manufactured volume holographic curved waveguide 200 are illustrated. The device can directly expose the holographic photosensitive material layer 221 on the curved waveguide layer 210, specifically, it can expose to form a volume holographic grating layer 220 for outcoupling, it can also expose to form a volume holographic grating layer 220 for turning, and it can also expose to form a volume holographic grating layer 220 for turning and outcoupling. Figure 4 As shown, the device includes a reference light generator 410 and a signal light generator 420 for interference exposure of a holographic photosensitive material layer 221 located in the outcoupling region and / or the turning region of the curved waveguide layer 210 to form a volume holographic grating layer 220 .

[0076] The reference light generator 410 is used to generate a single-pixel reference light corresponding to the i-th pixel. After the single-pixel reference light is coupled into the curved waveguide layer 210, it is totally reflected and propagated inside the curved waveguide layer 210, and irradiates the holographic photosensitive material layer 221 during the total reflection propagation process. The signal light generator 420 is used to generate a single-pixel signal light corresponding to the i-th pixel. The single-pixel signal light is directly emitted on the holographic photosensitive material layer 221. The single-pixel reference light and the single-pixel signal light interfere with each other on the holographic photosensitive material layer 221, and the interference fringes are recorded by the holographic photosensitive material layer 221.

[0077] The reference light generator 410 includes a reference light source 411, a first spatial light modulator 412, and a first lens group 413. The reference light source 411 generates a reference light and emits it to the first spatial light modulator 412. The first spatial light modulator 412 modulates the reference light into a first point light source of a single pixel corresponding to the i-th pixel and emits it to the first lens group 413. The first lens group 413 shapes the first point light source and emits it as the aforementioned single-pixel reference light. The first spatial light modulator 412 can be a transmissive spatial light modulator or a reflective spatial light modulator. The first lens group 413 can shape the first point light source into a parallel light beam (such as Figure 8 and Fig.12 ), or the first point light source can be shaped into a divergent beam (such as Fig. 9and Fig.13 ). In other words, the single-pixel reference light emitted by the first lens group 413 can be a parallel light beam or a divergent light beam, which has no effect on the reproduction of the virtual image.

[0078] The signal light generator 420 includes a signal light source 421, a second spatial light modulator 422, and a second lens group 423. The signal light source 421 generates signal light and emits it to the second spatial light modulator 422. The second spatial light modulator 422 modulates the signal light into a second point light source of a single pixel corresponding to the i-th pixel and emits it to the second lens group 423. The second lens group 423 shapes the second point light source and emits it as the aforementioned single-pixel signal light. The second spatial light modulator 422 can be a transmissive spatial light modulator or a reflective spatial light modulator. The second lens group 423 can shape the second point light source into a parallel light beam (such as Figures 8 and 9 ), or the second point light source can be shaped into a divergent beam (such as Figures 12-13 ). If the single pixel signal light is a parallel beam, the virtual image reproduced by the resulting volume holographic curved waveguide 200 is at infinity, such as Figures 6 and 7 If the single pixel signal light is a divergent beam, the virtual image reproduced by the resulting volume holographic curved waveguide 200 is at a finite distance, such as Figures 10-11 .

[0079] For a virtual image at finite distance, the virtual image I’ The distance VID from the second spatial light modulator 422 to the second lens group 423 is equal to the distance VID from the second spatial light modulator 422 to the holographic photosensitive material layer 221. d 1 and the distance from the second lens group 423 to the holographic photosensitive material layer 221 d 2, that is, VID = d 1+ d 2, wherein the distance from the second spatial light modulator 422 to the second lens group 423 is d 1 is equal to the object distance of the second lens group 423 u ,Right now d 1= u , the distance from the second lens group 423 to the holographic photosensitive material layer 221 d 2 is equal to the object distance of the second lens group 423 v ,Right now d 2= v According to the imaging formula 1 / u + 1 / v = 1 / f ( f represents the focal length of the second lens group 423), it can be seen that the focal length of the second lens group 423 is adjusted f , the distance from the second spatial light modulator 422 to the second lens group 423 d 1 and / or the distance from the second lens group 423 to the holographic photosensitive material layer 221d 2. Adjustable virtual image I’ The distance VID to the volume holographic grating layer 220 is adjusted, so as to produce a volume holographic curved waveguide 200 with different virtual image distances, so that the virtual image distance VID can also be adapted to people with different vision.

[0080] In order to facilitate the adjustment of the distance of the finite distance virtual image, the device may further include at least two of a first moving mechanism (not shown), a second moving mechanism (not shown), and a third moving mechanism (not shown). The signal light source 421 and the second spatial light modulator 422 are mounted on the first moving mechanism, so that the position of the second spatial light modulator 422 can be adjusted by the first moving mechanism, thereby adjusting the distance from the second spatial light modulator 422 to the second lens group 423. d 1. The second lens group 423 is mounted on the second moving mechanism so that the position of the second lens group 423 can be adjusted by the second moving mechanism, thereby adjusting the distance from the second spatial light modulator 422 to the second lens group 423 d 1 and / or the distance from the second lens group 423 to the holographic photosensitive material layer 221 d 2. The volume holographic curved waveguide 200 is mounted on the third moving mechanism so that the position of the volume holographic curved waveguide 200 can be adjusted by the third moving mechanism, thereby adjusting the distance from the second lens group 423 to the holographic photosensitive material layer 221 d 2.

[0081] The device may further include a stage (not shown) to install and position the volume holographic curved waveguide 200 to be exposed. The stage may be installed on the third moving mechanism so that the position of the stage can be adjusted by the third moving mechanism, that is, the distance between the second lens group 423 and the holographic photosensitive material layer 221 can be adjusted. d 2, thereby adjusting the distance of the finite distance virtual image.

[0082] The device may also include a coupler to couple the single-pixel reference light into the curved waveguide layer 210. The coupler includes a coupling grating 300, which may be a volume holographic grating or a surface relief grating, and may be fixedly mounted on the surface of the volume holographic curved waveguide 200 to be exposed by bonding or the like. In addition, the single-pixel reference light may also be coupled into the curved waveguide layer 210 through the coupling grating 300 provided by the volume holographic curved waveguide 200, and the coupling grating 300 may be a volume holographic grating or a surface relief grating, and may be fixed in the volume holographic curved waveguide 200 by bonding or the like. If the coupling grating 300 provided by the volume holographic curved waveguide 200 is a volume holographic grating, it may also be exposed and formed on the curved waveguide layer 210 by conventional exposure methods.

[0083] The device may also include a box body (not shown) having a cavity, in which the reference light generator 410, the signal light generator 420, the stage and other devices are installed, which is convenient for assembly and positioning of the devices and helps to create an environment suitable for exposure.

[0084] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A device for manufacturing a volume holographic curved waveguide, characterized in that: The device comprises a housing, a reference light generator and a signal light generator, wherein the housing has a cavity, the reference light generator and the signal light generator are installed in the cavity, and are used for interference exposure of a holographic photosensitive material layer located in an outcoupling region and / or a turning region to form a volume holographic grating layer; The reference light generator is used to generate a single-pixel reference light corresponding to the i-th pixel. After the single-pixel reference light is coupled into the curved waveguide layer, it is totally reflected and propagated inside the curved waveguide layer, and irradiates the holographic photosensitive material layer during the totally reflected propagation process. The signal light generator is used to generate a single-pixel signal light corresponding to the i-th pixel. The single-pixel signal light is directly emitted on the holographic photosensitive material layer. The single-pixel reference light and the single-pixel signal light interfere with each other on the holographic photosensitive material layer, and the interference fringes are recorded by the holographic photosensitive material layer.

2. The device for manufacturing a volume holographic curved waveguide according to claim 1, characterized in that: The reference light generator includes a reference light source, a first spatial light modulator and a first lens group. The reference light source generates reference light and emits it to the first spatial light modulator. The first spatial light modulator modulates the reference light into a first point light source of a single pixel corresponding to the i-th pixel and emits it to the first lens group. The first lens group shapes the first point light source and emits it as the single-pixel reference light.

3. The device for manufacturing a volume holographic curved waveguide according to claim 1 or 2, characterized in that: The signal light generator includes a signal light source, a second spatial light modulator and a second lens group. The signal light source generates signal light and emits it to the second spatial light modulator. The second spatial light modulator modulates the signal light into a second point light source of a single pixel corresponding to the i-th pixel and emits it to the second lens group. The second lens group shapes the second point light source and emits it as the single-pixel signal light.

4. The device for manufacturing a volume holographic curved waveguide according to claim 3, characterized in that: The single pixel signal light is a parallel light beam, and the virtual image reproduced by the resulting volume holographic curved waveguide is at infinity.

5. The device for manufacturing a volume holographic curved waveguide according to claim 3, characterized in that: The single pixel signal light is a divergent light beam, and the virtual image reproduced by the resulting volume holographic curved waveguide is at a finite distance.

6. The device for manufacturing a volume holographic curved waveguide according to claim 5, characterized in that: At least two of the focal length of the second lens group, the distance between the second lens group and the second spatial light modulator, and the distance between the second lens group and the holographic photosensitive material layer are adjustable to adjust the distance of the virtual image.

7. The device for manufacturing a volume holographic curved waveguide according to claim 6, characterized in that: The device also includes at least two of a first moving mechanism, a second moving mechanism, and a third moving mechanism. The signal light source and the second spatial light modulator are mounted on the first moving mechanism, the second lens group is mounted on the second moving mechanism, and the volume holographic curved waveguide is mounted on the third moving mechanism.

8. The device for manufacturing a volume holographic curved waveguide according to claim 6, characterized in that: The device also includes a stage for installing and positioning the volume holographic curved waveguide to be exposed, and the stage is installed in the cavity and on a third moving mechanism.

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