Preparation method of waveguide and emergent coupling grating thereof, and augmented reality head-up display for vehicle

Abstract

The invention relates to the technical field of optical display, in particular to a waveguide and a preparation method of an emergent coupling grating thereof, which are suitable for preparing large-area waveguides and can be applied to an augmented reality head-up display for a vehicle. According to the preparation method, a preset emergent coupling grating is defined on a substrate so as to carry out partition operation, the range of each partition is deviated from the center of the preset emergent coupling grating to the two ends, and the line width ratio of the grating formed by interference photoetching in the edge area of at least one partition is within a preset threshold value. Then, the first region is etched according to the set of set etching depths, and the second region is etched preferentially according to the set of etching depths of the first region, so that the purpose of reducing repeated etching among the sub-regions is achieved.

Description

Technical Field

[0001] This application relates to the field of optical display technology, and more particularly to a method for fabricating an outgoing coupling grating for a waveguide, and further to an optical display device applied to an augmented reality head-up display for vehicles. Background Technology

[0002] In augmented reality (AR) display devices and automotive head-up displays (HUDs), waveguide optical structures are often used to guide the images generated by the microdisplay into the user's field of vision. For example... Figure 1 The typical waveguide structure shown typically includes an incident coupling region 1, a folded region 2, and an outgoing coupling grating 3. The outgoing coupling grating often utilizes a surface relief grating (SRG) or a holographic grating to release the introduced light into the eyebox in a diffraction manner.

[0003] In existing technologies, interference lithography beams often have an approximately Gaussian distribution, with energy differences between the center and edge regions. Due to these varying exposure energies, the fill factor of the grating 4 formed in different regions deviates, leading to uneven diffraction efficiency. For example... Figure 2 As shown, the central region corresponds to an aspect ratio of approximately 50%, while the edge region has an aspect ratio of only approximately 35%. This deviation in aspect ratio will cause problems with the uniformity of the emitted light field.

[0004] like Figure 3 As shown, this non-uniformity will further cause differences in diffraction efficiency in the edge region, resulting in a decrease in the brightness and uniformity of the overall emitted light field.

[0005] Currently, to compensate for the diffraction efficiency deviations in the edge regions caused by energy distribution, existing technologies often require dividing the edge regions into multiple partitions. For example... Figure 3 As shown, different grating depths or structural parameters are set for different partitions (i.e., the edge partitions of X1~Xn are divided). However, as the number of partitions increases, the required grating depth type also increases, which in turn causes a significant increase in the number of etching process steps, increasing process complexity and cost. Summary of the Invention

[0006] To address the shortcomings of the prior art, this application provides a method for fabricating an output coupling grating for a waveguide. The core of this method lies in utilizing the "linewidth-depth-diffraction efficiency" correspondence established by interference lithography energy distribution to divide the output coupling grating into a first region and a second region. In the first region, a grating is first formed using a predetermined set of etching depths; in the second region, the etching depth set of the first region is preferentially used, allowing the second region to share the same etching depth as the first region, thereby reducing the number of repeated etching operations.

[0007] Specifically, the method for fabricating an emission coupling grating for a waveguide includes: providing a substrate and coating a photoresist layer on a patterned region of a predetermined emission coupling grating defined on the substrate; dividing the emission coupling grating into a first region and a second region, wherein the first region is located in a region off-center from the predetermined emission coupling grating, and the second region is located in an opposite region off-center from the first region; performing interference lithography on the first region and the second region such that the linewidth ratio of at least one edge region in the first region is within a predetermined threshold, and the linewidth ratio of at least one edge region in the second region is outside the predetermined threshold; etching the first region with a predetermined set of etching depths D0…Dn to form multiple different etching depths, where n is a positive integer; etching the second region according to one or more etching depths in the set of etching depths D0…Dn to improve the diffraction efficiency of the second region affected by the linewidth ratio not conforming to the predetermined threshold; and removing the photoresist layer and performing post-processing to form an emission coupling grating on the substrate.

[0008] In some embodiments, when the diffraction efficiency of at least one etching depth in the set of etching depths D0…Dn of the second region is not within the acceptable range, at least one additional etching depth Dn+1 is performed in the region where the diffraction efficiency is not within the acceptable range, so that the diffraction efficiency of the second region is within the acceptable range.

[0009] In some embodiments, the second region is selected at a position where the required etching depth of the second region overlaps to the maximum extent with the set of etching depths D0…Dn of the first region, in order to reduce the generation of the at least one additional etching depth Dn+1.

[0010] In some embodiments, the region of the second region includes the region where the linewidth ratio differs most from the preset threshold.

[0011] In some embodiments, the fabrication method further includes: providing a substrate with a minimum thickness value, based on calculation or simulation results, that maximizes the diffraction efficiency of the first region and the second region within the acceptable range, and that the first region and the second region can overlap.

[0012] In some embodiments, when the substrate deposits a metal layer, the photoresist layer is coated on the metal layer and subjected to interference photolithography.

[0013] This application also provides a waveguide, comprising: an incident coupling region for receiving a projected beam; a folding region disposed on one side of the incident coupling region for unfolding the projected beam; and an outgoing coupling grating prepared by the above-described preparation method disposed on one side of the folding region for diffracting the unfolded projected beam through the grating.

[0014] This application also provides an augmented reality head-up display for vehicles, comprising: a microdisplay providing a microimage, the microimage being in the form of a projected beam; and a waveguide that, after the projected beam passes through an incident coupling region and a folding region, diffracts through a grating formed with an outgoing coupling grating to generate an augmented reality image, and projects it into the driver's field of vision when viewing the windshield.

[0015] In conclusion, the following technical effects can be claimed in this case:

[0016] (1) Improve the uniformity of the light field: Before etching, the preset emission coupling grating is divided into at least two regions. The preset emission coupling grating is set into a first region and a second region on both sides offset from the center, and configured according to the energy distribution and linewidth ratio. This offset partitioning method allows the position of the newly added compensation region (second region) to overlap with the existing etching depth set (first region) to the greatest extent. By reusing the depth and the limited compensation depth, the difference in diffraction efficiency between the edge and the center is corrected, ensuring the brightness and uniformity of the overall emitted light field.

[0017] (2) Reduce process complexity: By prioritizing the reuse of existing etching depth sets, efficiency requirements can be met in most areas, with only a small amount of additional depth added in necessary small areas. This avoids the doubling of etching steps caused by excessive partitioning and depth diversification in traditional technologies, and significantly simplifies the process flow.

[0018] (3) Improve design flexibility: By changing the phase conditions in the waveguide through specific substrate thickness or other optical parameters (such as refractive index and center wavelength), the optimal depths corresponding to different partitions have higher overlap, further reducing the types of different etching depths on the substrate.

[0019] (4) Improve process yield and cost: Due to the significant reduction in etching depth types and steps, the accumulation of errors and failure rate in the process are relatively reduced, which helps to improve mass production yield and reduce the time and cost required for multiple photomasks and etching.

[0020] (5) Suitable for large-area applications: The waveguide output coupling grating prepared in this application can maintain high efficiency and high uniformity over a large area, and is particularly suitable for augmented reality display devices and automotive head-up displays (AR-HUD), which can ensure that drivers can obtain stable, clear and reliable virtual images in the eye box of the windshield. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a waveguide;

[0022] Figure 2 This is a schematic diagram showing the linewidth ratio between the center and edge regions caused by the Gaussian distribution of the light beam when forming a grating using interference lithography in the prior art.

[0023] Figure 3 In the prior art, in order to compensate for the uneven diffraction efficiency of the grating, it is necessary to divide the edge region of the outgoing coupling grating into multiple partitions and set up a schematic diagram of partitions with different etching depths.

[0024] Figure 4 A schematic diagram of the first region provided in this application, showing the beam deviating from the center at one end of the output coupling grating;

[0025] Figure 5 The embodiments provided in this application, relative to Figure 4 The other end, which is off-center, is set as a schematic diagram of the second zone;

[0026] Figure 6 The distribution of diffraction efficiency simulation results for the grating structure under different linewidth ratios (Fill Factor) and different etching depths (Depth) is shown in the figure.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1: Incident coupling region;

[0029] 2: Folding area;

[0030] 3: Outgoing coupling grating;

[0031] 4: Grating;

[0032] 100: Preset output coupling grating;

[0033] RS: Right side;

[0034] LS: Left side;

[0035] X1~Xn: Edge regions are divided;

[0036] D0~Dn: Overlapping etch depth partitions;

[0037] Dn+1: Additional etch depth partition. Detailed Implementation

[0038] Please refer to Figures 4-5 The fabrication and layout of an outgoing coupling grating for a waveguide are disclosed according to one embodiment. Figures 4-5The energy distribution of the interference lithography beam is illustrated using concentric depths (approximately Gaussian). The energy is higher at the center and lower at the edges, causing deviations in the linewidth ratio after exposure at different locations. To address this deviation, this embodiment first divides the patterned area of ​​the preset outgoing coupling grating 100 into sections for interference lithography, ensuring that the linewidth ratio on one side of one section is within a preset threshold. Multiple depths are then etched into the first and second sections, with each etching depth being an overlapping etching depth section D0~Dn (n being a positive integer). An additional etching depth section Dn+1 is added to the second section only when necessary. Through the coordinated design of the section positions and depth configurations, the outgoing diffraction efficiency is maintained within an acceptable range across the entire area, while minimizing the increase in etching types and steps.

[0039] The aforementioned comparison between the linewidth ratio and the preset threshold determines whether the linewidth ratio is less than, equal to, or greater than the set preset threshold. The term "within" or "outside" the preset threshold for the linewidth ratio here includes, but is not limited to, setting the preset threshold for the linewidth ratio to 0.40 (40%), such that areas with a linewidth ratio greater than this (>0.40) will be considered "within the preset threshold", and vice versa.

[0040] Specifically, the partitioning in this embodiment is at least divided into two partitions, and preferably, all interference lithography and etching operations can be completed with just two partitions. First, a first region is defined by a preset emission coupling grating 100 on the substrate, which is set at an off-center position (to... Figure 4 For example, the first region is off-center and leans towards the horizontal right (RS). The position of the first region can be pre-defined based on calculations or simulations, ensuring that the linewidth ratio of at least one edge region within the first region is within a preset threshold. Figure 4 For example, the position of the first region can ensure that the linewidth ratio of the formed outgoing coupling grating in the edge region of the right RS is within a preset threshold (such as greater than 0.4). This ensures that the diffraction efficiency will not be affected by the linewidth ratio, so that the diffraction efficiency falls within the acceptable range.

[0041] Furthermore, with Figure 5 For example, the second region is located in the opposite region of the first region, which is off-center. It is expected that the linewidth ratio deviation caused by the energy distribution in the second region should be large, and the linewidth ratio deviation will be most significant in the edge region of the left LS of the emission coupling grating.

[0042] The second region is then etched. Preferably, the etching depth of the second region is equal to or approximately equal to the set of etching depths of the first region (D0~Dn), thus reducing the number of etching operations. Therefore, if a layer-by-layer etching process is used, the first and second regions can be etched simultaneously on the same layer at the same or approximately the same etching depth. If a grayscale photoresist layer is used, multiple etching depths can be generated in a single etching operation, allowing the first and second regions to be etched simultaneously as well.

[0043] However, even if the second region has the same set of etching depths (D0~Dn) as the first region, if the diffraction efficiency of some areas in the second region is still not within the acceptable range (possible reasons include excessive linewidth deviation, which makes the existing set of etching depths (D0~Dn) unable to correct the diffraction efficiency to within the acceptable range), then it is necessary to perform compensation etching with an additional etching depth Dn+1 to ensure that the diffraction efficiency of the entire outgoing coupling grating on the substrate is within the acceptable range.

[0044] According to another embodiment, a transparent substrate, such as glass or a high-refractive-index polymer, with a thickness of approximately 1.5 to 3.0 mm, is first provided. After cleaning and drying, a photoresist layer with a thickness of, for example, 100 to 500 nm, is coated on a predetermined emission coupling grating 100 to be formed, and pre-baked. Then, the predetermined emission coupling grating 100 is patterned using interference lithography; in practice, a metal or dielectric hard shielding configuration can be used to complete subsequent multi-stage deep etching as needed. The interference lithography can employ laser interferometry (LIE), which uses two or more coherent laser beams to generate interference fringes within the photoresist layer to form a pattern, suitable for fabricating large-area waveguide gratings. Holographic exposure, phase-shifting lithography, or beam-shaping projection exposure can also be used; any method that can form a pattern on the photoresist layer can be applied to the process of this embodiment.

[0045] However, actual interference lithography beams typically exhibit a Gaussian distribution, such as... Figure 2 As shown, the energy is higher in the central region and gradually decreases at the edges. This distribution characteristic will cause a significant deviation in the grating linewidth ratio after exposure, which can be close to about 0.5 in the central region, while it may drop to about 0.35 in the edge region. The deviation in linewidth ratio directly causes uneven diffraction efficiency, resulting in poor diffraction efficiency and deviation in the uniformity of the emitted light field.

[0046] To quantitatively analyze the impact of linewidth and depth on diffraction efficiency, please refer to... Figure 6 The figure shows the simulated distribution of first-order diffraction efficiency under different linewidth ratios (horizontal axis 0.2~0.5) and different etching depths (vertical axis 30~250 nm). Figure 6 It is known that diffraction efficiency is highly correlated with both linewidth ratio and depth: for example, when the depth is approximately 100 nm, a linewidth ratio of 0.5 corresponds to approximately 26% diffraction efficiency, while a linewidth ratio of 0.35 corresponds to only approximately 21%; if the depth is increased to 110-115 nm, the decrease in diffraction efficiency can be compensated for, bringing it back to the acceptable range. Therefore, this embodiment is based on... Figure 6The revealed relationship between diffraction efficiency, depth, and linewidth ratio divides the preset output coupling grating 100 into a first region and a second region: the first region is located in the range of higher energy and linewidth close to the design center value; the second region is located in the range of lower energy and linewidth deviation. To reduce the need for additional etching depth, the geometric positions of the first and second regions are configured off-center. The center of the second region is selected through simulation at a position that maximizes the overlap between the required depth and the etching depth set D0~Dn of the first region, thereby minimizing the need for an additional depth Dn+1.

[0047] The grating structure of the first region is formed by a predetermined set of etching depths D0~Dn. The etching depth set D0~Dn can be established using simulation methods such as Rigorous Coupled-Wave Analysis (RCWA) / Finite-Difference Time-Domain (FDTD) or through measurement-lookup tables to establish a correspondence between "diffraction efficiency - depth - linewidth ratio". This ensures that the diffraction efficiency in the edge region of the pre-set emission coupling grating 100 adjacent to the first region is within an acceptable range (e.g., ±5% relative to the target diffraction efficiency η; if it exceeds ±10%, it is considered necessary to compensate). The compensation principle for the second region is to preferentially reuse one or more depths from the etching depth set D0~Dn to correct the diffraction efficiency of the second region caused by the linewidth ratio deviation to an acceptable range. Only when all existing depth sets D0~Dn cannot correct the diffraction efficiency of some areas in the second region to an acceptable range will an additional depth Dn+1 be added for compensation etching in that area. Therefore, the areas of the interference lithography irradiated by the first and second regions may overlap. However, this embodiment has ensured that the diffraction efficiency of one end region of the adjacent preset emission coupling grating 100 in the interference lithography of the first region is within the acceptable range (i.e., Figure 4 The center is slightly to the right of RS), and subsequent only need to perform interference lithography and small-area compensation etching on the second region (i.e. Figure 5 By positioning the output coupling grating slightly to the left of center (LS), the diffraction efficiency of the entire output coupling grating can be kept within acceptable limits.

[0048] In the actual etching process, multiple depths can be achieved by progressively etching layer by layer according to the pattern: first, the entire area is etched to the shallowest depth D0; the area reaching D0 is temporarily protected with photoresist or hard shielding, and the remaining areas are etched to D1; this process is repeated sequentially to D2…Dn; finally, only small areas requiring additional compensation are etched to Dn+1. This "layer-by-layer protection / layer-by-layer deepening" process can stably obtain multiple depths under a single cycle pattern, while keeping the number of etching steps and the area of ​​each new depth to a minimum. Specifically, when the substrate is a transparent substrate (such as glass, polymer, or silicon-based or other transparent substrates), wet chemical etching (such as hydrofluoric acid aqueous solution) or dry reactive ion etching (RIE) can be used, and the etching can be performed to the required depth according to the photoresist or hard shielding pattern. When the substrate is a high-refractive-index polymer, oxygen plasma etching or UV-assisted etching can be used to ensure etching uniformity and sidewall quality. When the substrate is silicon-based, deep reactive ion etching (DeepRIE) can be used to achieve multi-depth structures, and oxide or nitride layers can be used as hard shielding. Furthermore, when a metal layer (e.g., Cr, Al, or Au) is pre-formed on the substrate, the photoresist layer can be directly coated onto the metal layer for patterning; in this case, the metal layer acts as an etching hard shield to improve tolerance and ensure precise depth control. Alternatively, after photoresist pattern transfer, the metal layer can be wet-etched or dry-etched to form a metal shield, and then this metal shield can be used to protect the substrate during multi-stage deep etching. After completion, the photoresist and shielding layer are removed and the substrate is cleaned. The depth value can be confirmed using atomic force microscopy (AFM) or profilometry, and diffraction measurement or whole-system optical testing can verify that the outgoing diffraction efficiency and brightness uniformity meet the design acceptable range.

[0049] In yet another embodiment, before forming the resist pattern, first according to Figure 6 The relationship between diffraction efficiency, linewidth ratio, and etching depth is established by selecting a substrate thickness T to alter the propagation phase conditions within the waveguide (including the effective refractive index and phase accumulation / pairing conditions caused by the incident angle within the waveguide). Specifically, this can be achieved by scanning multiple thicknesses T using RCWA / FDTD at a given wavelength and material refractive index to obtain a function of the first-order diffraction efficiency η for a specific thickness T, given different FF and depths.

[0050] η(FF,depth|T);

[0051] Wherein, FF is the fill factor, which affects the aperture size of the grating; depth is the etching depth, which affects the phase of the grating-modulated light and the diffraction efficiency; and T is the substrate thickness, which affects the phase condition of the light in the waveguide.

[0052] η is also affected by wavelength λ, grating period Λ (Lambda), material refractive index n, incident / exit angle, polarization, etc.; these parameters are considered fixed conditions in this embodiment. Therefore, the diffraction efficiency η is mainly affected by the grating linewidth ratio and etching depth, and their relationship changes with the substrate thickness T. When the thickness T is different, the phase condition in the waveguide also changes, causing the optimal etching depth position corresponding to the same linewidth ratio to shift.

[0053] Next, the overlap of the required etching depth sets for the first and second regions at various thicknesses T is calculated. The minimum thickness value is selected that maximizes the efficiency of both regions within the acceptable range, while allowing them to share the same number of etching depths. To achieve this, ensuring similar or identical etching depths for each region necessitates the selection of a thicker substrate. Therefore, the minimum thickness value can be calculated using calculations or simulations. For example, when T = 2.0 mm, simulations show that the first region can have etching depths of 30 / 50 / 80 / 120 nm, while the second region requires 70 / 100 / 140 / 190 nm. The two depths have almost no overlap, leading to a significant increase in the number of etching passes. However, when the thickness T is set to 2.5 mm, due to the change in phase conditions, the efficiency-depth curve shifts towards the deeper end, allowing both regions to share 80 / 120 / 170 nm. The second region only needs an additional 230 nm depth for compensation to bring its diffraction efficiency back to the acceptable range. Therefore, by selecting a specific substrate thickness T, the overlap between the two regions can be effectively improved, the types and areas of newly added depths can be reduced, thereby reducing the number of etching operations and simplifying the process. In mass production practice, the thickness can be achieved by changing the substrate specifications, lamination bonding, or adding an equivalent waveguide layer, and tolerances can be set (e.g., T = 2.5 mm ± 0.1 mm) to ensure that the overlap is not affected by batch fluctuations. If the thickness is limited by the packaging, the same phase condition correction can also be achieved by using an equivalent method (such as slightly adjusting the refractive index of the waveguide layer or the exposure center wavelength), and the technical effect is similar to selecting a specific thickness.

[0054] In another embodiment, a waveguide is also disclosed, the structure of which includes an incident coupling region, a folded region, and an outgoing coupling grating. Specifically, the incident coupling region is located on one side of the waveguide and is equipped with a coupling grating or prism to receive the projected light beam and guide it into the substrate. The folded region is located on the side adjacent to the incident coupling region, and through a surface relief grating or holographic grating structure, the guided light beam is expanded within the waveguide by total internal reflection, achieving pupil expansion in both the horizontal and vertical directions. Finally, the outgoing coupling grating formed according to the aforementioned fabrication method is disposed on one side of the folded region. The outgoing coupling grating, through the design of a multi-depth grating and a partition compensation strategy, diffracts the expanded light beam uniformly and efficiently into a predetermined eyebox range, reconstructing the corresponding image.

[0055] In another embodiment, an augmented reality head-up display (AR-HUD) for automotive applications is disclosed. A beam of light is generated and projected via a microdisplay (which may consist of a laser light source, a microdisplay (such as DLP, LCOS, or Micro-LED), and focusing and collimating optical components). The projected beam is first coupled into the incident coupling region of a waveguide, then undergoes multiple total internal reflections and pupil expansions within the waveguide substrate via a folded region, and finally is released at an exit coupling grating fabricated using the aforementioned method. The exit coupling grating, through a multi-depth grating uniformity compensation design, can project the beam in a stable first-order diffraction direction and accurately project it onto the driver's eye level, allowing the driver to perceive a virtual augmented reality image on the windshield. The exit coupling grating fabricated using the aforementioned method avoids the brightness instability and process cost problems caused by uneven light field or excessive etching steps in traditional technologies.

[0056] In summary, by employing a partitioned, off-center, and depth-overlapping process in the waveguide's outgoing coupling grating, and combining this with a pre-selected specific substrate thickness, the grating structure effectively reduces the number and area of ​​additional etching depths when dealing with linewidth deviations caused by interference lithography beams. This method allows the outgoing coupling grating to maintain diffraction efficiency uniformity while significantly simplifying the process flow, improving yield, and reducing costs. Furthermore, the waveguide structure fabricated in this application can provide high-brightness, high-uniformity, and stable virtual images in augmented reality displays or automotive head-up displays.

Claims

1. A method for fabricating an output coupling grating for a waveguide, characterized in that, include: A substrate is provided, and a photoresist layer is coated on a patterned area of ​​a predetermined emission coupling grating defined on the substrate; The outgoing coupling grating is divided into a first region and a second region, wherein the first region is located in the region off-center of the preset outgoing coupling grating, and the second region is located in the opposite region off-center of the first region; Interference lithography is performed on the first region and the second region so that the linewidth ratio of the edge region on at least one side of the first region is within a preset threshold, and the linewidth ratio of the edge region on at least one side of the second region is outside the preset threshold. In the first region, etching is performed with a predetermined set of etching depths D0…Dn to form multiple different etching depths, where n is a positive integer; In the second region, etching is performed according to one or more etching depths in the etching depth set D0…Dn to improve the diffraction efficiency of the second region affected by the linewidth ratio not conforming to the preset threshold; and The photoresist layer is removed and post-processing is performed to form an emission coupling grating on the substrate.

2. The method for fabricating the waveguide output coupling grating as described in claim 1, characterized in that, When the diffraction efficiency of at least one of the etching depths in the second region set D0…Dn is not within an acceptable range, at least one additional etching depth Dn+1 is performed in the region where the diffraction efficiency is not within the acceptable range, so that the diffraction efficiency of the second region is within the acceptable range.

3. The method for fabricating the waveguide output coupling grating as described in claim 2, characterized in that, The second region is selected at a position that maximizes the overlap between the required etching depth of the second region and the etching depth set D0…Dn of the first region, in order to reduce the generation of the at least one additional etching depth Dn+1.

4. The method for fabricating the waveguide output coupling grating as described in claim 1, characterized in that, The second region includes the area where the linewidth ratio differs most from the preset threshold.

5. The method for fabricating the waveguide output coupling grating as described in claim 1, characterized in that, Also includes: The substrate provides a minimum thickness value for the etching depth that maximizes the diffraction efficiency of the first and second regions within the acceptable range, and allows the first and second regions to overlap, based on calculation or simulation results.

6. The method for fabricating the waveguide output coupling grating as described in claim 1, characterized in that, When the substrate is deposited with a metal layer, the photoresist layer is coated on the metal layer and subjected to interference photolithography.

7. A waveguide, characterized in that, include: Incident coupling region, used to receive the projected beam; A folding region, located on one side of the incident coupling region, is used to unfold the projected beam; as well as The outgoing coupling grating, prepared by the method of any one of claims 1 to 6, is disposed on one side of the folded region and is used to diffract the unfolded projected beam through the grating.

8. A vehicle-mounted augmented reality head-up display, characterized in that, include: A microdisplay that provides microimages, the microimages being in the form of projected light beams; As described in claim 7, the waveguide transmits the micro-image through the incident coupling region and the folding region, and then generates an augmented reality image through diffraction formed by the grating with the output coupling grating, which is then projected into the driver's field of vision on the windshield.

Images