Method for manufacturing a waveguide and head-mounted display device having a waveguide

Abstract

The present application provides a head-mounted display device. The head-mounted display device is configured in front of at least one eye of a user, and includes a display unit, a first waveguide and a second waveguide. The display unit is configured to provide an image beam. The first waveguide is located between the display unit and the second waveguide, and is configured to transmit the image beam to the second waveguide and adjust the light shape of the image beam to maintain the field of view angle and expand the pupil in a single dimension. The second waveguide is configured to transmit the image beam to the at least one eye of the user, and is capable of extending the light transmission path and providing a uniform image beam. In this way, the head-mounted display device is capable of having a large viewing angle and maintaining the viewing quality of the user.

Description

Technical Field

[0001] This invention relates to a method for fabricating an optical structure and an optical device having the optical structure, and more particularly to a method for fabricating a waveguide and a head-mounted display device having the waveguide. Background Technology

[0002] With advancements in display technology and people's desire for high technology, virtual reality and augmented reality technologies have matured, with head-mounted displays (HMDs) serving as the displays used to realize these technologies. The history of HMDs can be traced back to the US military in the 1970s, utilizing an optical projection system to project images or text from display elements onto the user's eyes. In recent years, with increasingly higher resolutions and smaller sizes and power consumption in microdisplays, HMDs have evolved into portable display devices. Beyond the military field, HMD technology has also grown and gained significant traction in other related fields such as industrial production, simulation training, stereoscopic displays, medicine, sports, navigation, and video games.

[0003] However, in the optical-mechanical design of head-mounted displays, achieving a large viewing angle and small size presents numerous design challenges. For example, due to the conservation of etendue, a larger field of view necessitates a larger f-number, resulting in a smaller pupil to improve the required modulation transfer function (MTF) value for the lens. Therefore, achieving a large field of view within a limited length requires considering pupil reduction. However, this pupil reduction also makes it more difficult for the image beam to expand within the waveguide, preventing a reduction in image beam brightness. Since the human pupil is only about 2.5 millimeters in size under illumination of 1000 to 2000 nits, ensuring that image light from all angles enters the eye smoothly with a small pupil becomes even more challenging.

[0004] On the other hand, in existing geometric waveguide designs, the pupil of the head-mounted display's optical engine needs to extend into the waveguide. This ensures that the minimum position of the pupil's beam contraction is at the point of entry into the main waveguide, maximizing the coupling of light into the waveguide to improve efficiency and effectively transmit large-angle light rays that are difficult to enter the waveguide smoothly. However, with this design, the length of the pupil and the waveguide it passes through need to be beyond a certain length. Consequently, when the space within the head-mounted display is insufficient to accommodate a waveguide of a certain length, large-angle image loss and reduced efficiency can easily occur.

[0005] The "Background Art" paragraph is only used to help understand the content of this invention. Therefore, the content disclosed in the "Background Art" paragraph may include some prior art that is not known to those skilled in the art. The content disclosed in the "Background Art" paragraph does not mean that the content or the problem to be solved by one or more embodiments of this invention was known or recognized by those skilled in the art before this application was filed. Summary of the Invention

[0006] To achieve one or more of the above-mentioned objectives, or other objectives, one embodiment of the present invention provides a head-mounted display device with a wide viewing angle, a reduced size of the head-mounted display device, a shortened waveguide element length, and a closer fit to the contours of the human face. It also expands the pupil in a single dimension and provides a uniform image beam.

[0007] The present invention also provides a method for fabricating a waveguide, which can easily fabricate a waveguide for expanding the pupil or extending the light transmission path.

[0008] Other objects and advantages of the present invention can be further understood from the technical features disclosed herein.

[0009] To achieve one or more of the above-mentioned objectives or other objectives, an embodiment of the present invention provides a head-mounted display device for placement in front of at least one eye of a user, comprising a display unit, a first waveguide, and a second waveguide. The display unit is used to provide an image beam. The first waveguide is located in the transmission path of the image beam and includes: a first plate; and a plurality of first optical microstructures located in the first plate, wherein the first optical microstructures include a central optical microstructure located on both sides of the main axis of the image beam, and edge optical microstructures located on both sides of the main axis of the image beam, wherein the central optical microstructure is closer to the main axis of the image beam than the edge optical microstructures, wherein after the image beam enters the first plate through a first surface, a portion of the image beam penetrates the central optical microstructure, and another portion of the image beam is transmitted to the corresponding edge optical microstructures through the central optical microstructure, and then exits the first plate from the second surface of the first plate after passing through the corresponding edge optical microstructures. A second waveguide is located in the transmission path of the image beam, wherein the first waveguide is located between the display unit and the second waveguide. The first waveguide is used to transmit the image beam to the second waveguide and adjust the light shape of the image beam. The second waveguide is used to transmit the image beam to at least one eye of the user. The second waveguide includes a second plate having a light-incident surface connected to a first surface and a second surface of the second plate, and a plurality of second optical microstructures located in the second plate, wherein each second optical microstructure has an optical surface that is inclined relative to the first surface of the second plate, and a plurality of light-guiding optical film patterns located on the optical surfaces of the second optical microstructures. The light-guiding optical film patterns are used to allow a portion of the image beam to pass through and reflect another portion of the image beam. After the image beam enters the second plate through the light-incident surface, a portion of the image beam passes through the light-guiding optical film patterns, and another portion of the image beam is reflected by the light-guiding optical film patterns and leaves the second plate from the second surface of the second plate.

[0010] In one embodiment of the present invention, the ratio between the orthographic projection area of ​​the light-guiding optical film pattern on the second plate and the area of ​​the second plate is less than 30%.

[0011] In one embodiment of the present invention, the angle between the first waveguide and the second waveguide is between 90 degrees and 135 degrees.

[0012] In one embodiment of the present invention, the first optical microstructure of the first waveguide is arranged along a first direction, the second optical microstructure of the second waveguide is arranged along a second direction, and the first direction is perpendicular to the second direction.

[0013] In one embodiment of the present invention, each of the first optical microstructures described above has an optical surface. The optical surface of the first optical microstructure extends from the main axis of the image beam and the first surface to the direction away from the main axis of the image beam and closer to the second surface, and is inclined relative to the first surface.

[0014] In one embodiment of the present invention, the first waveguide has a first optical region and a second optical region, which are located on both sides of the main axis of the image beam. The tilt direction of the optical surface of the first optical microstructure in the first optical region is mirror-symmetrical with the tilt direction of the optical surface of the first optical microstructure in the second optical region.

[0015] In one embodiment of the present invention, the first waveguide has at least one optical film, the at least one optical film being located on at least one of the optical surfaces of the first optical microstructure, and the optical film being used to allow a portion of the image beam to pass through and reflect another portion of the image beam.

[0016] In one embodiment of the present invention, at least one optical film located on the aforementioned central optical microstructure or edge optical microstructure has a reflectivity to the image beam that is greater than its transmittance to the image beam.

[0017] In one embodiment of the present invention, the first optical microstructure further includes a plurality of relay optical microstructures, and there is at least one relay optical microstructure between the central optical microstructure and the edge optical microstructure. A portion of the image beam from the central optical microstructure passes through the relay optical microstructure and is transmitted to the corresponding edge optical microstructure. Another portion of the image beam from the central optical microstructure is reflected by the relay optical microstructure and leaves the first plate from the second surface.

[0018] In one embodiment of the present invention, at least one optical film located on the above-mentioned relay optical microstructure has a reflectivity of less than its transmittance to the image beam.

[0019] In one embodiment of the present invention, the first plate includes a first structural layer and a second structural layer. The first structural layer of the first plate has a plurality of first inclined surfaces and a plurality of first connecting surfaces, wherein each first connecting surface connects different ends of adjacent first inclined surfaces to form a first serrated structure. The second structural layer of the first plate has a plurality of second inclined surfaces and a plurality of second connecting surfaces, wherein each second connecting surface connects different ends of adjacent second inclined surfaces to form a second serrated structure, and the second inclined surfaces correspond to the first inclined surfaces, and the second connecting surfaces correspond to the first connecting surfaces, so that the first serrated structure and the second serrated structure fit together, and the second inclined surfaces contact the first inclined surfaces to form the optical surface of the first optical microstructure.

[0020] In one embodiment of the present invention, the first waveguide has at least one optical film, which is located on at least one of the first inclined surface of the first structural layer and the second inclined surface of the second structural layer, and the optical film is used to allow a portion of the image beam to pass through and reflect another portion of the image beam.

[0021] In one embodiment of the present invention, the minimum distance between two adjacent light-guiding optical film patterns described above is less than the size of the user's pupil.

[0022] In one embodiment of the present invention, the ratio of the size of each of the light-guiding optical film patterns to the minimum distance between two adjacent light-guiding optical film patterns is between 0.6 and 0.7.

[0023] In one embodiment of the present invention, the second plate includes a first structural layer and a second structural layer. The first structural layer of the second plate has a plurality of first inclined surfaces and a plurality of first connecting surfaces, wherein each first connecting surface connects different ends of adjacent first inclined surfaces to form a first serrated structure. The second structural layer of the second plate has a plurality of second inclined surfaces and a plurality of second connecting surfaces, wherein each second connecting surface connects different ends of adjacent second inclined surfaces to form a second serrated structure, and the second inclined surfaces correspond to the first inclined surfaces, and the second connecting surfaces correspond to the first connecting surfaces, so that the first serrated structure and the second serrated structure fit together, and the second inclined surfaces contact the first inclined surfaces to form the optical surface of the second optical microstructure.

[0024] In one embodiment of the present invention, the second waveguide has a first optical region and a second optical region, wherein the first optical region is located between the light-incident surface and the second optical region, and the first sawtooth structure, the second sawtooth structure, and the second optical microstructure are located in the second optical region. The second waveguide also includes a light guide film. The light guide film is located on a light-guiding surface inside the second waveguide, the light-guiding surface is located in the first optical region and is parallel to the first surface, wherein the light guide film is used to allow a portion of the image beam to pass through and reflect another portion of the image beam, and the image beam passing through the light guide film is transmitted in the second waveguide in a manner of total internal reflection.

[0025] In one embodiment of the present invention, the first structural layer of the second waveguide described above further has a first plane, and the second structural layer further has a second plane, the second plane being in contact with the first plane to form a light guiding surface.

[0026] To achieve one, some, or all of the above-mentioned objectives, or other objectives, an embodiment of the present invention provides a method for fabricating a waveguide for a head-mounted display device, wherein the waveguide is used to transmit an image beam, and the method for fabricating the waveguide includes the following steps: Providing a first structural layer, wherein the first structural layer has a plurality of first inclined surfaces and a plurality of first connecting surfaces, wherein each first connecting surface connects different ends of adjacent first inclined surfaces to form a first sawtooth structure. Providing a second structural layer, wherein the second structural layer has a plurality of second inclined surfaces and a plurality of second connecting surfaces, wherein each second connecting surface connects different ends of adjacent second inclined surfaces to form a second sawtooth structure. Forming at least one optical film on at least one first inclined surface of the first structural layer or at least one second inclined surface of the second structural layer, wherein the at least one optical film is used to allow a portion of the image beam to pass through and reflect another portion of the image beam. The first structural layer and the second structural layer are joined together, wherein the second inclined surface corresponds to the first inclined surface and the second connecting surface corresponds to the first connecting surface, so that the first sawtooth structure and the second sawtooth structure can fit together, and the second inclined surface contacts the first inclined surface to form multiple optical surfaces of multiple optical microstructures.

[0027] In one embodiment of the present invention, the waveguide is a first waveguide, and a first plate of the first waveguide is formed by bonding the first structural layer and the second structural layer. The optical microstructure is a plurality of first optical microstructures. The first waveguide has a first optical region and a second optical region. The first optical region and the second optical region are respectively located on both sides of the main axis of the image beam. The tilt direction of the optical surface of the first optical microstructure in the first optical region is mirror-symmetrical with the tilt direction of the optical surface of the first optical microstructure in the second optical region.

[0028] In one embodiment of the present invention, the first optical microstructure includes two central optical microstructures and two edge optical microstructures. The central optical microstructures are located on both sides of the main axis of the image beam. The edge optical microstructures are located on both sides of the main axis of the image beam, with the central optical microstructures being closer to the main axis of the image beam than the edge optical microstructures. After the image beam enters the first plate through the first surface, a portion of the image beam penetrates the central optical microstructure, while the other portion of the image beam is transmitted to the corresponding edge optical microstructure via the central optical microstructure and then exits the first plate after passing through the corresponding edge optical microstructure.

[0029] In one embodiment of the present invention, the waveguide is a second waveguide, and a second plate of the second waveguide is formed by bonding the first structural layer and the second structural layer. The optical microstructure comprises a plurality of second optical microstructures, and the method for forming at least one optical film includes the following steps: Providing a photomask having a plurality of through-holes; Overlapping the photomask with the first or second structural layer, wherein the projection surface of the through-holes on the first or second structural layer overlaps with at least one first inclined surface of the first structural layer or at least one second inclined surface of the second structural layer; Forming a plurality of light-guiding optical film patterns of at least one optical film through the plurality of through-holes on the at least one first inclined surface of the first structural layer or at least one second inclined surface of the second structural layer, wherein after an image beam enters the second plate via an incident surface, a portion of the image beam penetrates the light-guiding optical film pattern, and another portion of the image beam is reflected by the light-guiding optical film pattern and leaves the second plate, and the ratio between the orthographic projection area of ​​the light-guiding optical film pattern on the second plate and the area of ​​the second plate is less than 30%.

[0030] In one embodiment of the present invention, the photomask is a flat structure or has a serrated structure. When the photomask has a serrated structure, the serrated structure can match the first serrated structure or the second serrated structure, and the through hole of the photomask penetrates multiple inclined surfaces of the serrated structure. The inclined surfaces of the serrated structure correspond to at least one first inclined surface of the first structural layer or at least one second inclined surface of the second structural layer.

[0031] In one embodiment of the present invention, the second waveguide has a first optical region and a second optical region, wherein the first optical region is located between the light-incident surface and the second optical region, and the first structural layer further has a first plane, and the second structural layer further has a second plane, the first plane and the second plane are located in the first optical region, and the first sawtooth structure, the second sawtooth structure and the second optical microstructure are located in the second optical region. The waveguide fabrication method further includes the following steps: forming a light guide film on the first plane or the second plane, wherein the light guide film is used to allow a portion of the image beam to pass through and reflect another portion of the image beam; when the first structural layer and the second structural layer are joined, the first plane and the second plane contact each other to form a light guide surface, and the image beam passing through the light guide film on the light guide surface is transmitted in the second waveguide by total internal reflection.

[0032] Based on the above, the embodiments of the present invention have at least one of the following advantages or effects. In the embodiments of the present invention, through the configuration of the first waveguide, the image beam can be transmitted to the second waveguide, and the beam shape is adjusted to maintain the field of view and expand the pupil in a single dimension. Through the configuration of the second waveguide, the transmission path of the image beam can be extended and has good uniformity. Thus, the head-mounted display device can have a wide viewing angle and provide good viewing quality.

[0033] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings. Attached Figure Description

[0034] Figure 1A This is a top view schematic diagram of a user wearing a head-mounted display device according to an embodiment of the present invention.

[0035] Figure 1B yes Figure 1A A schematic diagram of the architecture of a head-mounted display device.

[0036] Figure 2A yes Figure 1B A perspective view of the first waveguide.

[0037] Figure 2B yes Figure 2A Exploded view of the first waveguide.

[0038] Figure 2C yes Figure 2A A side view of the first waveguide.

[0039] Figure 2D yes Figure 2A The optical path diagram of the first waveguide.

[0040] Figure 3A yes Figure 1B A schematic diagram of the explosion of the second waveguide.

[0041] Figure 3B It is a kind of production Figure 3A A schematic diagram of the photomask for the second waveguide.

[0042] Figure 3C It is another kind of production Figure 3A A front view of the photomask of the second waveguide.

[0043] Figure 3D yes Figure 3C A schematic diagram of the bottom view of the photomask.

[0044] Figure 3E yes Figure 1B A front view of the second waveguide.

[0045] Figure 4A yes Figure 1A A schematic diagram of the optical path of a head-mounted display device.

[0046] Figure 4B yes Figure 1A A schematic diagram of the optical path of a head-mounted display device.

[0047] Figure 4C This is a schematic diagram of the optical path of a comparative head-mounted display device.

[0048] List of reference numerals

[0049] 100: First Waveguide

[0050] 101R: First Optical Zone

[0051] 102R: Second Optical Zone

[0052] 110 First Plate

[0053] 110F: Optical film

[0054] 110OS: Optical surface

[0055] 111: First structural layer

[0056] 111IS: First inclined plane

[0057] 111LS: First connecting surface

[0058] 111S: First Surface

[0059] 111ZS: First serrated structure

[0060] 112: Second structural layer

[0061] 112IS: Second inclined plane

[0062] 112LS: Second connecting surface

[0063] 112S: Second Surface

[0064] 112ZS: Second serrated structure

[0065] 120: First optical microstructure

[0066] 121: Central Optical Microstructure

[0067] 122: Relay Optical Microstructure

[0068] 123: Edge optical microstructure

[0069] 200: Second Waveguide

[0070] 201R: First Optical Zone

[0071] 202R: Second Optical Zone

[0072] 210: Second plate

[0073] 210F: Optical film

[0074] 210FP: Light-guiding optical film pattern

[0075] 210OS: Optical surface

[0076] 211: First structural layer

[0077] 211IS: First inclined plane

[0078] 211LS: First Connecting Surface

[0079] 211PS: First plane

[0080] 211S: First Surface

[0081] 211ZS: First serrated structure

[0082] 212: Second structural layer

[0083] 212IS: Second inclined plane

[0084] 212LS: Second connecting surface

[0085] 212ZS: Second serrated structure

[0086] 212S: Second Surface

[0087] 212PS: Second plane

[0088] 220: Second optical microstructure

[0089] 300: Head-mounted display device

[0090] 310: Lighting System

[0091] 320: Display Unit

[0092] D1: First Direction

[0093] D2: Second Direction

[0094] EY: Eyes

[0095] GF: Light guide film

[0096] GS: Light guide surface

[0097] IB: Image Beam

[0098] LS: Lens Module

[0099] O: Main spindle

[0100] OM: Light Mask

[0101] PS: Flat plate structure

[0102] ST: Light Bar

[0103] TH: Through-hole

[0104] WG: Waveguide Components

[0105] ZS: Serrated structure

[0106] θ: included angle. Detailed Implementation

[0107] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the accompanying drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front, or back, are merely for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the present invention.

[0108] Figure 1A This is a top view schematic diagram of a user wearing a head-mounted display device according to an embodiment of the present invention. Figure 1B yes Figure 1A A schematic diagram of the architecture of a head-mounted display device. Please refer to... Figure 1A and Figure 1B In this embodiment, the head-mounted display device 300 is disposed in front of at least one eye (EY) of a user and includes an illumination system 310, a display unit 320, and a waveguide element WG including a first waveguide 100 and a second waveguide 200. The display unit 320 is used to provide an image beam (IB). In this embodiment, the display unit 320 includes, for example, a digital micromirror device (DMD) for converting the illumination beam (first illumination beam) from the illumination system 310 into an image beam (IB). In one embodiment, the display unit 320 includes, for example, a liquid crystal on silicon (LCoS) display device; the present invention does not limit the type of display unit 320. The display unit 320 may also include a prism for transmitting the illumination beam.

[0109] Specifically, such as Figure 1A and Figure 1B As shown, after the image beam IB leaves the display unit 320, it is transmitted to the waveguide element WG via the lens module LS and converges at the aperture ST.

[0110] In this embodiment, the first waveguide 100 is located between the display unit 320 and the second waveguide 200. The first waveguide 100 is used to transmit the image beam IB to the second waveguide 200 and adjust the light shape of the image beam IB. The second waveguide 200 is used to transmit the image beam IB to at least one eye EY of the user.

[0111] In this embodiment, the aperture stop ST is located outside the display unit 320, while the display unit 320 is located between the illumination system 310 and the aperture stop ST along the transmission path of the image beam IB. The aperture stop ST is located within the first waveguide 100, the second waveguide 200, or at the connection point of the first waveguide 100 and the second waveguide 200. The aperture stop ST is the location with the minimum cross-sectional area of ​​the beam contraction of the image beam IB. For example, in this embodiment, the minimum cross-sectional area of ​​the beam contraction of the image beam IB is defined as the pupil, and the shape of the pupil is, for example, circular. However, in this embodiment, the shape and size of the pupil at the aperture stop ST are only for illustrative purposes, and the invention is not limited thereto.

[0112] In this embodiment, the image beam IB converges to the aperture stop ST and then diverges via the waveguide element WG after passing through the aperture stop ST. In this embodiment, the waveguide element WG has an optical inlet end located on the first waveguide 100 and an optical outlet end located on the second waveguide 200. The optical inlet end is adapted to receive the image beam IB. The image beam IB is transmitted to the human eye via the waveguide element WG and emitted from the optical outlet end.

[0113] like Figure 1A and Figure 1B As shown, in this embodiment, the waveguide element WG formed by the combination of the first waveguide 100 and the second waveguide 200 is a one-sided waveguide architecture. Furthermore, in this embodiment, the angle θ between the first waveguide 100 and the second waveguide 200 is set to an obtuse angle, between 90 degrees and 135 degrees. Thus, the aperture ST of the head-mounted display device is located within the waveguide element WG, enabling the maximum amount of image beams to couple into the waveguide element WG, thereby improving efficiency and effectively transmitting large-angle image beams that are difficult to enter the waveguide element WG. The required length from the lens module LS to the aperture ST can also be shortened to less than 8 millimeters. Compared to existing head-mounted displays, with the same optomechanical structure (i.e., illumination system 310 and display unit 320), the length from the lens module LS to the aperture ST in existing head-mounted displays is about 11 mm. Therefore, it can be seen that the size of the waveguide element WG composed of the first waveguide 100 and a second waveguide 200 in this embodiment can be reduced, making it easier to install in a head-mounted display device, and reducing the risk of missing large-angle image frames and reduced efficiency.

[0114] Furthermore, the structure of the waveguide element WG, composed of the first waveguide 100 and the second waveguide 200, in this embodiment can effectively conform to the user's head shape, thus shortening the length of the waveguide element WG. Specifically, when the first waveguide 100 and the second waveguide 200 are perpendicular to each other, a gap will be created between the waveguide element WG and the user's face, therefore the required length of the waveguide element WG must be longer. However, as Figure 1A As shown, in this embodiment, the angle between the first waveguide 100 and the second waveguide 200 is between 90 degrees and 135 degrees. This conforms to the user's head shape, minimizing the gap between the waveguide element WG and the user's face, and further shortening the required length of the waveguide element WG. Consequently, the image beam IB can enter the eye more quickly with less diffusion, thus magnifying the eye's viewing angle.

[0115] The following will be paired Figures 2A to 3E The structures of the first waveguide 100 and the second waveguide 200 will be further explained separately.

[0116] Figure 2A yes Figure 1B A perspective view of the first waveguide. Figure 2B yes Figure 2A Exploded view of the first waveguide. Figure 2C yes Figure 2A A side view of the first waveguide. Figure 2D yes Figure 2A A schematic diagram of the optical path of the first waveguide. (See diagram below.) Figures 2A to 2C As shown, in this embodiment, the first waveguide 100 includes a first plate 110 and a plurality of first optical microstructures 120. The first plate 110 has a first surface 111S and a second surface 112S. The plurality of first optical microstructures 120 are located in the first plate 110. The first optical microstructures 120 include two central optical microstructures 121, a plurality of relay optical microstructures 122, and two edge optical microstructures 123. The two central optical microstructures 121 are respectively located on both sides of the main axis O of the image beam IB. The two edge optical microstructures 123 are respectively located on both sides of the main axis O of the image beam IB, and the two central optical microstructures 121 are closer to the main axis O of the image beam IB than the two edge optical microstructures 123. Furthermore, at least one relay optical microstructure 122 exists between the central optical microstructures 121 and the edge optical microstructures 123.

[0117] Furthermore, such as Figures 2A to 2CAs shown, in this embodiment, each first optical microstructure 120 has an optical surface 110OS. The optical surface 110OS of the first optical microstructure 120 extends from the main axis O near the image beam IB in a direction away from the main axis O of the image beam IB and is inclined relative to the first surface 111S. Furthermore, in this embodiment, the first waveguide 100 has a first optical region 101R and a second optical region 102R. The first optical region 101R and the second optical region 102R are located on both sides of the main axis O of the image beam IB. The tilt direction of the optical surface 110OS of the first optical microstructure 120 located in the first optical region 101R is mirror-symmetrical to the tilt direction of the optical surface 110OS of the first optical microstructure 120 located in the second optical region 102R.

[0118] Furthermore, such as Figure 2C As shown, the first waveguide 100 has at least one optical film 110F, which is located on at least one of the optical surfaces 110OS of the first optical microstructure 120. The optical film 110F is used to allow a portion of the image beam IB to pass through and reflect another portion of the image beam IB. For example, the first waveguide 100 can be fabricated by the following steps. First, as... Figure 2B As shown, a first structural layer 111 and a second structural layer 112 are provided. The first structural layer 111 has a plurality of first inclined surfaces 111IS and a plurality of first connecting surfaces 111LS, and the second structural layer 112 also has a plurality of second inclined surfaces 112IS and a plurality of second connecting surfaces 112LS. Each first connecting surface 111LS of the first structural layer 111 connects to different ends of adjacent first inclined surfaces 111IS to form a first sawtooth structure 111ZS, and each second connecting surface 112LS of the second structural layer 112 connects to different ends of adjacent second inclined surfaces 112IS to form a second sawtooth structure 112ZS. Furthermore, at least one optical film 110F is formed on at least one first inclined surface 111IS of the first structural layer 111 or at least one second inclined surface 112IS of the second structural layer 112. In other words, at least one optical film 110F is located on at least one of the first inclined surfaces 111IS of the first structural layer 111 and the second inclined surfaces 112IS of the second structural layer 112.

[0119] Next, the first structural layer 111 and the second structural layer 112 are joined, wherein the second inclined surface 112IS corresponds to the first inclined surface 111IS, and the second connecting surface 112LS corresponds to the first connecting surface 111LS, so that the first sawtooth structure 111ZS and the second sawtooth structure 112ZS can fit together, and the second inclined surface 112IS contacts the first inclined surface 111IS to form multiple optical surfaces 110OS of multiple optical microstructures. In this way, after the first structural layer 111 and the second structural layer 112 are joined, the first plate 110 of the first waveguide 100 can be formed.

[0120] Thus, as Figure 2D As shown, when the image beam IB enters the first plate 110 via the first surface 111S, a portion of the image beam IB penetrates the two central optical microstructures 121, while another portion is transmitted via the central optical microstructures 121 to the corresponding edge optical microstructures 123. Furthermore, a portion of the image beam IB from the central optical microstructure 121 penetrates the relay optical microstructure 122 and is transmitted to the corresponding edge optical microstructure 123, while another portion of the image beam IB from the central optical microstructure 121 is reflected by the relay optical microstructure 122 and exits the first plate 110 via the second surface 112S. The image beam IB that is not reflected by the relay optical microstructure 122 and exits the first plate 110 without being reflected by the relay optical microstructure 122 can continue to propagate within the first plate 110 and exits the first plate 110 via the second surface 112S after passing through the corresponding edge optical microstructure 123. Figure 2D As can be seen from the image beam IB, it will be mirrored around the main axis O and emitted parallel to the first plate 110.

[0121] Specifically, in this embodiment, the optical films 110F located on different optical microstructures can have different reflectivity designs due to different reflection / transmission requirements. For example, in this embodiment, at least one optical film 110F located on the two central optical microstructures 121 or the edge optical microstructure 123 has a reflectivity greater than its transmittance to the image beam IB, while at least one optical film 110F located on the relay optical microstructure 122 has a reflectivity less than its transmittance to the image beam IB. Thus, the central optical microstructure 121 with high reflectivity can effectively reflect the image beam IB and extend its transmission path backward. The relay optical microstructure 122 with high transmittance can extend the transmission path of the image beam IB backward while also reflecting the image beam IB and causing it to leave the first plate 110, and the edge optical microstructure 123 with high reflectivity can effectively cause the image beam IB to leave the first plate 110. Thus, as Figure 1B and Figure 2C As shown, the image beam IB leaving the first plate 110 of the first waveguide 100 is transmitted to the second waveguide 200, thus the pupil of the image beam IB transmitted to the second waveguide 200 can be effectively enlarged.

[0122] Furthermore, since the image beam IB can further expand its pupil through the optical film 110F, the characteristics of the optical film 110F also affect the uniformity of the entire pupil, including brightness uniformity and color uniformity. Moreover, when the pupil uniformity is not uniform, it also affects the uniformity of the color points entering the pupil. Because the illumination beam used to form the image beam IB originates from the light-emitting element of the illumination system 310, and because the color light emitted by the light-emitting element of the illumination system 310 has different distributions, the uniformity of the pupils for different colors will have different uniformities under different colors. For example, when the pupil distributions for red, green, and blue light are not the same, the color uniformity will be poor, but when the pupil uniformity for red, green, and blue light is exactly the same, the color point uniformity will be greatly improved. Therefore, in this embodiment, the optical film 110F can also adjust the reflectivity / transmittance for different wavelengths of colored light. Thus, when it is confirmed that the characteristics of the optical film 110F and the uniformity of the pupil for different colors of light are both in an ideal state, the color dot distribution output by the display unit 320 will be close to the color dot distribution seen by the human eye pupil, thereby improving the viewing quality.

[0123] In addition, Figure 2C In this paper, the number of optical films 110F is exemplified by 10 optical films located on different optical microstructures, but the present invention is not limited thereto. The number of optical films 110F may vary depending on different optomechanical systems, but there will always be at least one optical film.

[0124] Figure 3A yes Figure 1B A schematic diagram of the explosion of the second waveguide. Figure 3B It is a kind of production Figure 3A A schematic diagram of the photomask for the second waveguide. Figure 3C It is another kind of production Figure 3A A front view of the photomask of the second waveguide. Figure 3D yes Figure 3C A schematic diagram of the bottom view of the photomask. Figure 3E yes Figure 1B A front view schematic diagram of the second waveguide. (See diagram below.) Figures 3A to 3E As shown, in this embodiment, the second waveguide 200 includes a second plate 210, a plurality of second optical microstructures 220, and a plurality of light-guiding optical film patterns 210FP. The second plate 210 has a first surface 211S, a second surface 212S, and a light-incident surface for connecting the second surface 212S. The plurality of second optical microstructures 220 are located in the second plate 210, wherein each second optical microstructure 220 has at least one optical surface 210OS, and the optical surface 210OS of the second optical microstructure 220 is inclined relative to the first surface 211S.

[0125] Furthermore, such as Figure 3Aand Figure 3B As shown, multiple light-guiding optical film patterns 210FP are located on the optical surface 210OS of the second optical microstructure 220, and the light-guiding optical film patterns 210FP are used to allow a portion of the image beam IB to pass through and reflect another portion of the image beam IB. For example, the second waveguide 200 can be fabricated by the following steps. First, a first structural layer 211 and a second structural layer 212 are provided, wherein the first structural layer 211 has multiple first inclined surfaces 211IS and multiple first connecting surfaces 211LS, and the second structural layer 212 also has multiple second inclined surfaces 212IS and multiple second connecting surfaces 212LS. Each first connecting surface 211LS connects different ends of adjacent first inclined surfaces 211IS to form a first sawtooth structure 211ZS, and each second connecting surface 212LS connects different ends of adjacent second inclined surfaces 212IS to form a second sawtooth structure 212ZS.

[0126] At least one optical film 210F is formed on at least one first inclined surface 211IS of the first structural layer 211 or at least one second inclined surface 212IS of the second structural layer 212, and the method of forming at least one optical film 210F includes the following steps: providing a photomask OM, and the photomask OM having a plurality of through holes TH. For example, such as Figure 3B As shown, the photomask OM can be a flat plate structure PS.

[0127] Furthermore, such as Figure 3B As shown, in this embodiment, the photomask OM overlaps with the first structural layer 211 or the second structural layer 212, and the projection surface of the through-hole TH on the first structural layer 211 or the second structural layer 212 overlaps with at least one first inclined surface 211IS of the first structural layer 211 or at least one second inclined surface 212IS of the second structural layer 212. Thus, by means of... Figure 3C and Figure 3D The multiple through-holes TH of the photomask OM shown can also form multiple light-guiding optical film patterns 210FP of at least one optical film 210F on at least one first inclined surface 211IS of the first structural layer 211 or at least one second inclined surface 212IS of the second structural layer 212. However, the present invention is not limited thereto. It is worth noting that, in another embodiment, the photomask OM can also be a sawtooth structure (e.g., Figure 3C and Figure 3D (As shown).

[0128] Furthermore, such as Figure 3C and Figure 3DAs shown, when the photomask OM has a sawtooth structure, the sawtooth structure can match the first sawtooth structure 211ZS or the second sawtooth structure 212ZS, and the through hole TH of the photomask OM penetrates multiple inclined surfaces of the sawtooth structure. The inclined surfaces of the sawtooth structure correspond to at least one first inclined surface 211IS of the first structural layer 211 or at least one second inclined surface 212IS of the second structural layer 212. Next, make... Figure 3C and Figure 3D The photomask OM shown overlaps with either the first structural layer 211 or the second structural layer 212, and the projection surface of the through-hole TH on the first structural layer 211 or the second structural layer 212 overlaps with at least one first inclined surface 211IS of the first structural layer 211 or at least one second inclined surface 212IS of the second structural layer 212. Thus, through... Figure 3C and Figure 3D The multiple through holes TH of the photomask OM shown can also form multiple light-guiding optical film patterns 210FP of at least one optical film 210F on at least one first inclined surface 211IS of the first structural layer 211 or at least one second inclined surface 212IS of the second structural layer 212.

[0129] Next, the first structural layer 211 and the second structural layer 212 are joined, wherein the second inclined surface 212IS corresponds to the first inclined surface 211IS, and the second connecting surface 212LS corresponds to the first connecting surface 211LS, so that the first sawtooth structure 211ZS and the second sawtooth structure 212ZS can fit together, and the second inclined surface 212IS contacts the first inclined surface 211IS to form multiple optical surfaces 210OS of multiple optical microstructures. In this way, after the first structural layer 211 and the second structural layer 212 are joined, a second plate 210 of the second waveguide 200 can be formed, wherein the optical microstructures are multiple second optical microstructures 220, and multiple light-guiding optical film patterns 210FP of at least one optical film 210F are formed on the optical surface 210OS.

[0130] For example, in this embodiment, the first optical microstructure 120 of the first waveguide 100 is arranged along a first direction D1, and the second optical microstructure 220 of the second waveguide 200 is arranged along a second direction D2, with the first direction D1 and the second direction D2 being perpendicular. Thus, because the optical microstructures in the first waveguide 100 and the second waveguide 200 are configured differently, the functions of the second waveguide 200 and the first waveguide 100 are also different. The primary function of the first waveguide 100 is to transmit the image beam IB to the second waveguide 200 and to effectively enlarge the pupil of the image beam IB coupled to the second waveguide 200. The primary function of the second waveguide 200 is to ensure that the image beam IB is transmitted to the user's eye and to provide a larger viewing angle. Therefore, the light-guiding optical film pattern 210FP of the second waveguide 200 can also be designed as a circular outline, and the size of each light-guiding optical film pattern 210FP is not consistent, and there is a gap between them, so that the image beam IB from the first waveguide 100 can be transmitted further in the second waveguide 200, effectively controlling the large-angle image beam IB to be reflected by the light-guiding optical film pattern 210FP of the second waveguide 200 to finally enter the eye EY, thereby forming an optical system of a head-mounted display device 300 with a large viewing angle.

[0131] More specifically, the spacing between the light-guiding optical film patterns 210FP must be defined according to the size of the human pupil to avoid the user perceiving the light-guiding optical film patterns 210FP as too dense, thereby ensuring a good visual experience. For example, in this embodiment, the minimum distance between two adjacent light-guiding optical film patterns 210FP is less than or equal to the size of the user's pupil. For example, the minimum distance between two adjacent light-guiding optical film patterns 210FP is approximately 0.5 times the size of the user's pupil.

[0132] On the other hand, the perceived density of the light guide optical film pattern 210FP varies depending on the user's pupil size. Larger pupils receive more light, significantly reducing the perceived density of the light guide optical film pattern 210FP. Therefore, the size of the light guide optical film pattern 210FP can be controlled during the design process to avoid excessive density. The ratio of the size of each light guide optical film pattern 210FP to the minimum distance between two adjacent light guide optical film patterns 210FP is between 0.6 and 0.7, with a preferred ratio of 0.6. For example, in this embodiment, with a minimum distance of 1.5 mm between two adjacent light guide optical film patterns 210FP, the size of the light guide optical film pattern 210FP can be controlled to below 1.1 mm, thus providing a better visual experience for the user.

[0133] Thus, when the image beam IB from the first waveguide 100 enters the second plate 210 via the incident surface, a portion of the image beam IB can penetrate the light-guiding optical film pattern 210FP, while another portion of the image beam IB is reflected by the light-guiding optical film pattern 210FP and exits the second plate 210 from the second surface 212S. More specifically, in this embodiment, the ratio between the projected area of ​​the light-guiding optical film pattern 210FP on the second plate 210 and the area of ​​the second plate 210 is less than 30%, thereby obtaining a better field of view. For example, the area of ​​the light-guiding optical film pattern 210FP is approximately 20% of the area of ​​the second plate 210, and since the light-guiding optical film pattern 210FP has a transmittance of approximately 50%, the overall field of view efficiency of the optical system of the head-mounted display device 300 can be increased to approximately 90%, thereby achieving a good field of view.

[0134] Figure 4A yes Figure 1A A schematic diagram of the optical path of a head-mounted display device. Figure 4B yes Figure 1A A simulated brightness data diagram of the image beam presented by the head-mounted display device. Figure 4C This is a simulated brightness data graph of the image beam presented by a head-mounted display device without a light guide film, serving as a comparative example. Furthermore, as... Figure 4AAs shown, in this embodiment, the second waveguide 200 has a first optical region 201R and a second optical region 202R. The first optical region 201R is located between the light-incident surface and the second optical region 202R. The first sawtooth structure 211ZS, the second sawtooth structure 212ZS, and the second optical microstructure 220 are located in the second optical region 202R. The second waveguide 200 also includes a light-guiding film GF. The light-guiding film GF is located on a light-guiding surface GS inside the second waveguide 200. The light-guiding surface GS is located in the first optical region 201R and is parallel to the first surface 211S.

[0135] Furthermore, the light guide film GF can be fabricated simultaneously when forming multiple light guide optical film patterns 210FP of at least one optical film 210F. For example, in this embodiment, the first structural layer 211 of the second waveguide 200 also has a first plane 211PS, and the second structural layer 212 also has a second plane 212PS. While forming multiple light guide optical film patterns 210FP of at least one optical film 210F, the light guide film GF is also formed on the first plane or the second plane. Then, after the first structural layer 211 and the second structural layer 212 are joined, the second plane contacts the first plane to form a light guide surface GS, and the light guide film GF can be formed on it.

[0136] Specifically, such as Figure 4A As shown, the light guide film GF allows a portion of the image beam IB to pass through and reflects another portion of the image beam IB. The image beam IB passing through the light guide film GF is transmitted in the second waveguide 200 by total internal reflection. In this way, the uniformity of the image beam IB entering the second waveguide 200 can be further enhanced.

[0137] Furthermore, such as Figure 4B As shown, when a light guide film GF is provided, the light guide film GF can effectively increase the density of the image beam IB. Furthermore, since the light guide film GF is located inside the second waveguide 200, compared to the case where the light guide film GF is coated on the outer surface of the second waveguide 200, its uniformity can be significantly increased while maintaining its optical efficiency. Thus, the image image presented by the image beam IB transmitted to the human eye through the second waveguide 200 in the head-mounted display device 300 can have good uniformity, and the image is less prone to defects. In contrast, as... Figure 4C As shown, when the light guide film GF is not configured, the uniformity of the image beam IB transmitted to the human eye through the second waveguide 200 in the head-mounted display device 300 is significantly reduced. Therefore, some areas of the image beam IB entering the human eye will be lacking light. As a result, the image seen by the human eye will be defective and incomplete, thus affecting the viewing quality.

[0138] In summary, the embodiments of the present invention have at least one of the following advantages or effects. In the embodiments of the present invention, through the configuration of the first waveguide, the image beam can be transmitted to the second waveguide, and the beam shape is adjusted to maintain the field of view and expand the pupil in a single dimension. Through the configuration of the second waveguide, the transmission path of the image beam can be extended and has good uniformity. Thus, the head-mounted display device can have a wide viewing angle and provide good viewing quality.

[0139] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Any simple equivalent changes and modifications made in accordance with the claims and specification of the present invention are still within the scope of this patent. Furthermore, no embodiment or claim of the present invention needs to achieve all the objectives, advantages, or features disclosed in the present invention. In addition, the abstract and title of the invention are only used to assist in patent document retrieval and are not intended to limit the scope of the invention. Moreover, the terms "first," "second," etc., mentioned in this specification or claims are only used to name elements or distinguish different embodiments or scopes, and are not used to limit the upper or lower limit of the number of elements.

Claims

1. A head-mounted display device, characterized by comprising: For configuring in front of at least one eye of a user, comprising a display unit, a first waveguide and a second waveguide, wherein the display unit is configured to provide an image beam; the first waveguide is located on a transmission path of the image beam, and the first waveguide comprises a first plate body, a plurality of optical films and a plurality of first optical microstructures, wherein each of the plurality of optical films is configured to transmit a portion of the image beam and reflect another portion of the image beam, the plurality of first optical microstructures are located in the first plate body, and the plurality of first optical microstructures comprise two central optical microstructures, a plurality of relay optical microstructures and two edge optical microstructures, wherein at least one of the plurality of optical films is located on one of the two central optical microstructures or one of the two edge optical microstructures, and the at least one optical film located on one of the two central optical microstructures or one of the two edge optical microstructures has a reflectivity to the image beam greater than a transmittance to the image beam; and wherein at least another one of the plurality of optical films is located on at least one of the plurality of relay optical microstructures, and the at least another one of the plurality of optical films located on at least one of the plurality of relay optical microstructures has a reflectivity to the image beam less than a transmittance to the image beam; the two central optical microstructures are respectively located on two sides of a main axis of the image beam; the two edge optical microstructures are respectively located on two sides of the main axis of the image beam, and the two central optical microstructures are closer to the main axis of the image beam than the two edge optical microstructures, and at least one of the plurality of relay optical microstructures is arranged between one of the two central optical microstructures and one of the two edge optical microstructures, wherein after the image beam enters the first plate body through a first surface of the first plate body, a portion of the image beam transmits through the two central optical microstructures and exits the first plate body, another portion of the image beam is reflected by the two central optical microstructures and is transmitted in the first plate body, and a portion of the another portion of the image beam is transmitted to the two edge optical microstructures and exits the first plate body from a second surface of the first plate body; the second waveguide is located on the transmission path of the image beam, wherein the first waveguide is located between the display unit and the second waveguide, the first waveguide is configured to transmit the image beam to the second waveguide and adjust a light shape of the image beam, the second waveguide is configured to transmit the image beam to the at least one eye of the user, and the second waveguide comprises a second plate body, a plurality of second optical microstructures and a plurality of light guiding optical film patterns, wherein the second plate body has a light entrance surface connecting a first surface and a second surface of the second plate body; The plurality of second optical microstructures are located in the second plate body, wherein each of the plurality of second optical microstructures has an optical face, and a plurality of the optical faces of the plurality of second optical microstructures are respectively inclined with respect to the first surface of the second plate body. The plurality of light guide optical film patterns are located on a plurality of the optical faces of the plurality of second optical microstructures, and the plurality of light guide optical film patterns are used to transmit a portion of the image light beams and reflect another portion of the image light beams, wherein after the image light beams enter the second plate body through the light entrance face, a portion of the image light beams transmits the plurality of light guide optical film patterns, and another portion of the image light beams is reflected by the plurality of light guide optical film patterns and then exits the second plate body from the second surface of the second plate body.

2. The head-mounted display apparatus of claim 1, wherein A ratio between a projected area of the plurality of light guide optical film patterns on the second plate body and an area of the second plate body is less than 30%.

3. The head-mounted display apparatus of claim 1, wherein, An included angle between the first waveguide and the second waveguide is between 90 degrees and 135 degrees.

4. The head-mounted display apparatus of claim 1, wherein, The plurality of first optical microstructures of the first waveguide are arranged along a first direction, and the plurality of second optical microstructures of the second waveguide are arranged along a second direction, and the first direction is perpendicular to the second direction.

5. The head-mounted display apparatus of claim 1, wherein, Each of the plurality of first optical microstructures has an optical face, and a plurality of the optical faces of the plurality of first optical microstructures are respectively inclined with respect to the first surface of the first plate body from a position close to a principal axis of the image light beams and the first surface of the first plate body to a position away from the principal axis of the image light beams and close to the second surface of the first plate body.

6. The head-mounted display apparatus of claim 5, wherein, The first waveguide has a first optical zone and a second optical zone, the first optical zone and the second optical zone are respectively located on two sides of the principal axis of the image light beams, and an inclined direction of a plurality of the optical faces of the plurality of first optical microstructures located in the first optical zone is mirror-symmetrical to an inclined direction of a plurality of the optical faces of the plurality of first optical microstructures located in the second optical zone.

7. The head-mounted display apparatus of claim 5, wherein, The first plate body comprises a first structure layer and a second structure layer, wherein The first structure layer has a plurality of first inclined surfaces and a plurality of first connecting surfaces, wherein each of the first connecting surfaces connects different ends of adjacent ones of the plurality of first inclined surfaces to form a first zigzag structure; The second structure layer has a plurality of second inclined surfaces and a plurality of second connecting surfaces, wherein each of the second connecting surfaces connects different ends of adjacent ones of the plurality of second inclined surfaces to form a second zigzag structure, and the plurality of second inclined surfaces correspond to the plurality of first inclined surfaces, and the plurality of second connecting surfaces correspond to the plurality of first connecting surfaces, so that the first zigzag structure and the second zigzag structure are matched, and the plurality of second inclined surfaces and the plurality of first inclined surfaces are in contact to form a plurality of the optical faces of the plurality of first optical microstructures.

8. The head-mounted display apparatus of claim 7, wherein, The first waveguide has at least one optical film located on at least one of the plurality of first inclined surfaces of the first structure layer and the plurality of second inclined surfaces of the second structure layer, and the optical film is used to transmit a portion of the image light beams and reflect another portion of the image light beams.

9. The head-mounted display apparatus of claim 1, wherein, A minimum distance between two adjacent light guide optical film patterns is less than a size of a user's pupil.

10. The head-mounted display apparatus of claim 9, wherein, A ratio between a size of each light guide optical film pattern and the minimum distance between two adjacent light guide optical film patterns is between 0.6 and 0.

7.

11. The head-mounted display apparatus of claim 9, wherein, The second plate body includes a first structure layer and a second structure layer, wherein The first structure layer has a plurality of first inclined surfaces and a plurality of first connecting surfaces, wherein each of the first connecting surfaces connects different ends of adjacent first inclined surfaces to form a first sawtooth structure; The second structure layer has a plurality of second inclined surfaces and a plurality of second connecting surfaces, wherein each of the second connecting surfaces connects different ends of adjacent second inclined surfaces to form a second sawtooth structure, and the plurality of second inclined surfaces correspond to the plurality of first inclined surfaces, the plurality of second connecting surfaces correspond to the plurality of first connecting surfaces, so that the first sawtooth structure and the second sawtooth structure match, and the plurality of second inclined surfaces and the plurality of first inclined surfaces are in contact to form the plurality of optical surfaces of the plurality of second optical microstructures.

12. The head-mounted display apparatus of claim 11, wherein, The second waveguide has a first optical zone and a second optical zone, wherein the first optical zone is located between the light entrance surface and the second optical zone, and the first sawtooth structure, the second sawtooth structure, and the plurality of second optical microstructures are located in the second optical zone, and the second waveguide further includes: A light guide film located on a light guide surface inside the second waveguide, the light guide surface being located in the first optical zone and parallel to the first surface of the second plate body, wherein the light guide film is used to transmit a portion of the image light beams and reflect another portion of the image light beams, and the image light beams passing through the light guide film are transmitted in the second waveguide in a total reflection manner.

13. The head-mounted display apparatus of claim 12, wherein, The first structure layer further has a first plane, and the second structure layer further has a second plane, and the second plane is in contact with the first plane to form the light guide surface.

14. A method for fabricating a waveguide for a head-mounted display device, characterized in that, The waveguide is used to transmit image light beams, and a manufacturing method of the waveguide includes: providing a first structure layer, wherein the first structure layer has a plurality of first inclined surfaces and a plurality of first connecting surfaces, and each of the first connecting surfaces connects different ends of adjacent first inclined surfaces to form a first sawtooth structure; providing a second structure layer, wherein the second structure layer has a plurality of second inclined surfaces and a plurality of second connecting surfaces, and each of the second connecting surfaces connects different ends of adjacent second inclined surfaces to form a second sawtooth structure; forming a plurality of optical films on at least one of the plurality of first inclined surfaces of the first structure layer or at least one of the plurality of second inclined surfaces of the second structure layer, wherein each of the plurality of optical films is configured to transmit a portion of the image beam and reflect another portion of the image beam; and joining the first structure layer and the second structure layer, wherein the plurality of second inclined surfaces correspond to the plurality of first inclined surfaces, the plurality of second connecting surfaces correspond to the plurality of first connecting surfaces, the first serrated structure and the second serrated structure are capable of fitting together, and the plurality of second inclined surfaces and the plurality of first inclined surfaces are in contact to form a plurality of optical surfaces of a plurality of optical microstructures, wherein when the waveguide is a first waveguide, the first structure layer and the second structure layer form a first plate body of the first waveguide after being joined, the plurality of optical microstructures are a plurality of first optical microstructures, the plurality of first optical microstructures include two central optical microstructures, a plurality of relay optical microstructures, and two edge optical microstructures, at least one optical film of the plurality of optical films located on the two central optical microstructures or the two edge optical microstructures has a reflectivity greater than a transmittance for the image beam, at least another optical film of the plurality of optical films located on the plurality of relay optical microstructures has a reflectivity less than a transmittance for the image beam, the two central optical microstructures are located on two sides of a principal axis of the image beam, the two edge optical microstructures are located on two sides of the principal axis of the image beam, the two central optical microstructures are closer to the principal axis of the image beam than the two edge optical microstructures, and at least one of the plurality of relay optical microstructures is disposed between one of the two central optical microstructures and one of the two edge optical microstructures, and wherein after the image beam enters the first plate body through a first surface of the first plate body, a portion of the image beam transmits through the two central optical microstructures and exits the first plate body, another portion of the image beam is reflected by the two central optical microstructures and is transmitted within the first plate body, and a portion of the another portion of the image beam is transmitted to the two edge optical microstructures and exits the first plate body from a second surface of the first plate body.

15. The method of claim 14, wherein, The first waveguide has a first optical zone and a second optical zone, the first optical zone and the second optical zone are located on two sides of the principal axis of the image beam, respectively, the plurality of optical surfaces of the plurality of first optical microstructures located in the first optical zone have a mirror symmetry with the plurality of optical surfaces of the plurality of first optical microstructures located in the second optical zone.

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