Projection optical system and AR optical display device

Abstract

The embodiment of the invention provides a projection optical system and AR optical display equipment. Wherein the optical system sequentially comprises a display, a prism, a second optical element group, a first optical element group and a diaphragm along an optical path; the display is used for emitting an image light beam; the second optical element group comprises at least three lenses; the first optical element group comprises at least one off-axis lens; the first optical element group is used for realizing off-axis turning of a light path, the thickness ratio a of at least one off-axis lens is greater than or equal to 2 and less than or equal to 5, and the thickness ratio a is the ratio of the thickness of the thickest area to the thickness of the thinnest area of the off-axis lens; and the second optical element group is used for correcting off-axis aberration and modulating a light-emitting angle.

Description

Technical Field

[0001] This application relates to the field of optical display technology, and more specifically, to a projection optical system and an AR optical display device. Background Technology

[0002] With the development of augmented reality (AR) glasses technology, higher demands are being placed on their internal projection optical engines: not only do they need high resolution and low power consumption, but they are also evolving towards miniaturization and lightweight design. Conventional projection optical systems are mostly coaxial systems, meaning the curvature centers of all optical elements are roughly on the same straight line. When such systems are applied to space-constrained AR glasses, in order to project the image beam to a specific location (such as the coupling area of ​​an optical waveguide device), the entire optical lens often needs to be tilted. This inevitably leads to an increase in the size of the projection optical system in one dimension, contradicting the goal of device miniaturization. Therefore, how to effectively reduce the size of the projection optical system while ensuring high luminous efficiency and excellent image quality has become a pressing technical problem in this field. Summary of the Invention

[0003] The purpose of this application is to provide a new technology solution for a projection optical system and an AR optical display device to solve the problem of increased size caused by lens tilt in existing AR projection optical engines.

[0004] In a first aspect, embodiments of this application provide a projection optical system, which includes, along the optical path, the following components in sequence: A display used to emit beams of light for images; Prism; The second optical element group includes at least three lenses; A first optical element group, comprising at least one off-axis lens; and, Aperture; The first optical element group is used to realize the off-axis reversal of the optical path, and the thickness ratio a of at least one off-axis lens satisfies 2≤a≤5, wherein the thickness ratio a is the ratio of the thickness of the thickest region to the thickness of the thinnest region of the off-axis lens; The second optical element group is used to correct off-axis aberrations and modulate the emission angle.

[0005] Optionally, the off-axis lens in the first optical element group that satisfies 2≤a≤5 has a non-rotationally symmetric thickness distribution, and its thinnest region is located at the lower edge of the lens. The thickness distribution is used to enable the image beam to achieve spatial off-axis folding relative to the system optical axis.

[0006] Optionally, the central tangents of the two surfaces of the off-axis lens form an included angle θ, which satisfies: 4°≤θ≤40°.

[0007] Optionally, the second optical element group includes at least three off-axis optical surfaces.

[0008] Optionally, the total optical power φ of the projection optical system satisfies the following relationship with the optical power φ1 of the first optical element group and the optical power φ2 of the second optical element group: 0.5≤|φ1-φ2| / φ≤2.

[0009] Optionally, the total length TTL of the projection optical system satisfies: TTL≤14mm, where TTL is the distance from the surface of the aperture to the light-emitting surface of the display in the direction of the optical axis of the system.

[0010] Optionally, the first optical element group consists of only one off-axis lens; The second optical element group consists of three or four lenses.

[0011] Optionally, the off-axis lens in the first optical element group is a first lens with a thickness ratio a of 3.3; The second optical element group consists of a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially from the aperture side to the display side; wherein, both surfaces of the second lens and the image-side surface of the third lens are off-axis optical surfaces.

[0012] Optionally, the off-axis lens in the first optical element group is a first lens with a thickness ratio a of 2.3; The second optical element group consists of a second lens, a third lens, and a fourth lens arranged sequentially from the aperture side to the display side; wherein the image-side surface of the second lens and both surfaces of the third lens are off-axis optical surfaces.

[0013] Optionally, the off-axis lens in the first optical element group is a first lens with a thickness ratio a of 4; The second optical element group consists of a second lens, a third lens, and a fourth lens arranged sequentially from the aperture side to the display side; wherein the image-side surface of the second lens, the two surfaces of the third lens, and the two surfaces of the fourth lens are all off-axis optical surfaces.

[0014] Optionally, the telecentricity Tele of the projection optical system satisfies: Tele < 1°, where Tele is the exit angle of the main ray of the projection optical system from the display.

[0015] Secondly, embodiments of this application provide an AR optical display device, the AR optical display device comprising: Optical waveguide devices; and, As described in the first aspect, the projected optical system has its outgoing beam coupled into the optical waveguide device via the aperture.

[0016] The beneficial effects of this application are as follows: Addressing the issue of increased system size in existing AR projection optical engines due to their coaxial optical design, which necessitates tilting the core mirror group (or optical lens) to guide the image beam into the coupling region of the optical waveguide device, this application solves the problem by incorporating off-axis lenses with a specific thickness ratio (2≤a≤5) in the first optical element group. This achieves controllable optical path deflection within the system, completely eliminating the need for tilting the entire mirror group at the optical architecture level, providing a fundamental solution for system miniaturization. Furthermore, by configuring a second optical element group for aberration correction and emission angle modulation, the projection optical system achieves a compact structure while maintaining excellent image quality and high light energy utilization, comprehensively meeting the integrated performance requirements of miniaturization, high image quality, and high luminous efficiency.

[0017] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.

[0019] Figure 1 This is one of the structural and optical path diagrams of the projection optical system provided in the embodiments of this application; Figure 2 A schematic diagram of an off-axis lens provided in an embodiment of this application; Figure 3 for Figure 1 The diagram shows a dot array of the projection optical system. Figure 4 for Figure 1 The diagram shows the modulation transfer function of the projection optical system. Figure 5 for Figure 1 The diagram shows the grid distortion of the projection optical system. Figure 6 for Figure 1 The diagram shows the transverse chromatic aberration of the projection optical system. Figure 7 This is the second structural and optical path diagram of the projection optical system provided in the embodiments of this application; Figure 8 for Figure 7 The diagram shows a dot array of the projection optical system. Figure 9 for Figure 7 The diagram shows the modulation transfer function of the projection optical system. Figure 10 for Figure 7 The diagram shows the grid distortion of the projection optical system. Figure 11 for Figure 7 The diagram shows the transverse chromatic aberration of the projection optical system. Figure 12 The third structural and optical path diagram of the projection optical system provided in the embodiments of this application; Figure 13 for Figure 12 The diagram shows a dot array of the projection optical system. Figure 14 for Figure 12 The diagram shows the modulation transfer function of the projection optical system. Figure 15 for Figure 12 The diagram shows the grid distortion of the projection optical system. Figure 16 for Figure 12 The diagram shows the transverse chromatic aberration of the projection optical system.

[0020] Explanation of reference numerals in the attached figures: 1. Monitor; 2. Prism; 3. Second optical element group; 31. Second lens; 311. Third optical surface; 312. Fourth optical surface; 32. Third lens; 321. Fifth optical surface; 322. Sixth optical surface; 33. Fourth lens; 331. Seventh optical surface; 332. Eighth optical surface; 34. Fifth lens; 341. Ninth optical surface; 342. Tenth optical surface; 4. First optical element group; 41. First lens; 411. First optical surface; 412. Second optical surface; 01. Aperture. Detailed Implementation

[0021] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0022] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0023] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0024] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0026] The projection optical system and AR optical display device provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0027] According to one embodiment of this application, a projection optical system is provided, see [link to relevant documentation]. Figure 1 , Figure 7 and Figure 12 The projection optical system, along the optical path, sequentially includes: a display 1, a prism 2, a second optical element group 3, a first optical element group 4, and an aperture 01. The display 1 is used to emit an image beam. The second optical element group 3 includes at least three lenses. The first optical element group 4 includes at least one off-axis lens. The first optical element group 4 is used to achieve off-axis reversal of the optical path, and the thickness ratio α of at least one off-axis lens satisfies 2 ≤ a ≤ 5, where the thickness ratio α is the ratio of the thickness of the thickest region to the thickness of the thinnest region of the off-axis lens; the second optical element group 3 is used to correct off-axis aberrations and modulate the emission angle.

[0028] The projection optical system provided in this application is mainly integrated into the micro-projection optical engine of devices such as AR glasses and head-mounted displays, serving as its core imaging engine. This projection optical system, through its innovative off-axis optical architecture, efficiently processes image beams from, for example, microdisplays (such as Micro-OLED or LCOS), ultimately outputting a bright, high-definition intermediate image plane with low telecentricity. This image plane can be projected and coupled into subsequent waveguide devices or freeform mirrors, merging with the real-world field of view. Its compact physical size and superior optical performance allow the entire projection optical engine to be embedded in the narrow temples or frames of, for example, AR glasses, thereby powerfully promoting the evolution of terminal devices towards thinner and lighter designs while ensuring high image quality.

[0029] For example, see Figure 1 The projection optical system provided in this application has an optical path that passes sequentially from the display side where the image source is located to the human eye observation side via the following optical elements: display 1, prism 2, second optical element group 3, first optical element group 4, and aperture 01. This optical path layout constitutes a complete image generation, transmission, and projection optical path.

[0030] In this system, the display 1 serves as the image source for the entire projection optical system, emitting an image beam carrying image information. The image beam first enters the prism 2, which is used to fold the light path, adjust the propagation direction, or perform polarization splitting, thereby achieving miniaturization of the projection optical system while meeting specific optical requirements. Subsequently, the image beam passes sequentially through the second optical element group 3 and the first optical element group 4, undergoing optical modulation such as aberration correction and light path deflection. Finally, the modulated image beam exits through the aperture 01. The aperture 01 controls the light transmission of the projection optical system, defines the imaging depth of field, and serves as the optical reference plane for the entire projection optical system.

[0031] The first optical element group 4 is the core component designed in this application to overcome the size problem of traditional projection optical systems. In traditional coaxial optical design, in order to make the beam ultimately point to the human eye, the entire projection optical system or its core lens group (also known as optical lens) needs to be tilted relative to the device housing. However, this will significantly increase the space occupied by the optical projection system in devices such as AR glasses.

[0032] This application introduces an off-axis optical architecture, placing the first optical element group 4 at one end of the optical path near the aperture 01. Its core function is to achieve spatial deflection of the light beam. This optical design forms an off-axis optical path by deviating the beam propagation path or optical surface from the system's main axis. Therefore, the image beam no longer needs to propagate symmetrically along the optical axis, but is directly guided to the human eye through the controlled spatial deflection achieved by the first optical element group 4, thus eliminating the need for tilting the entire system or its core components. This design directly solves the problem of large size caused by the tilted layout of the system at the optical architecture level, laying a key technological foundation for the high integration and miniaturization of projection optical systems in devices such as AR glasses.

[0033] The first optical element group 4 includes at least one off-axis lens (such as...) Figure 1 The first lens 41 shown is characterized by a thickness ratio α (defined as the ratio of the thickness of the thickest region to the thinnest region of the off-axis lens) optimized to 2 ≤ α ≤ 5. This ratio reflects the difference in thickness distribution, stemming from the non-rotationally symmetric surface structure of the off-axis lens designed to accommodate off-axis optical paths. Lenses with specific thickness distributions (such as...) Figure 1 The first lens 41 shown can apply differentiated deflection to light in different areas, thereby efficiently guiding the light beam to achieve the desired off-axis propagation path. This optical design replaces the traditional optical system's method of tilting the entire lens assembly to guide the light beam, eliminating the structural dependence on tilted mounting space at the optical configuration level and laying the foundation for system miniaturization.

[0034] The second optical element group 3 is disposed between the prism 2 and the first optical element group 4, and consists of at least three lenses, see [link to relevant documentation]. Figure 1 , Figure 7 and Figure 12 The second optical element group 3 performs the dual functions of image quality optimization and light energy control in the entire projection optical system.

[0035] Since the off-axis architecture adopted by the first optical element group 4 introduces asymmetric off-axis aberrations such as astigmatism, field curvature and coma while realizing the miniaturization of the projection optical system, the second optical element group 3, through the coordinated design of the curvature, thickness, spacing and material optical parameters (refractive index and Abbe number) of its multiple lenses, produces an optical compensation effect that is equal in magnitude and opposite in phase to the aforementioned aberrations, thereby achieving effective cancellation of aberrations in the entire field of view and ensuring that the system has high-definition imaging performance.

[0036] In addition, the second optical element group 3 modulates the emission angle of the image beam from the display 1. By controlling the convergence or divergence of the light, it improves the matching efficiency with subsequent optical components such as optical waveguides, ensuring that more light energy is effectively conducted and utilized, thereby comprehensively improving the system's light efficiency, which is especially suitable for power-sensitive AR optical display devices.

[0037] The projection optical system provided in this application embodiment has a functional division of labor between the first optical element group 4 and the second optical element group 3: the first optical element group 4 breaks the spatial symmetry of the system by introducing an off-axis optical path, thus laying the architectural foundation for the miniaturization of the overall structure; the second optical element group 3 is used to correct off-axis aberrations caused by the off-axis design and improves light energy utilization by adjusting the angle of the image beam, thereby ensuring clear imaging and sufficient brightness while making the system compact. These two element groups work together to achieve the goal of high image quality and high light efficiency in projection display within a limited space.

[0038] The projection optical system provided in this application embodiment also includes a display 1. The display 1 serves as the image source of the projection optical system, and its function is to generate and emit image beams. In practical applications, the display 1 can, for example, be a miniature high-pixel-density display, such as Micro-OLED or LCOS, to meet the stringent requirements of AR display devices (which are a type of near-eye display device) for high resolution, high contrast, and small size.

[0039] The projection optical system provided in this application embodiment also includes a prism 2. The prism 2 is disposed behind the light-emitting side of the display 1 and is a key optical path processing element. Its core function is not simple transmission, but rather the orientation and shaping of the light beam emitted by the display. Specifically, it can achieve one or more of the following functions: Folded optical path: By changing the direction of the light beam through reflection, the length of the optical path can be compressed within a limited physical space, which is one of the key means to achieve miniaturization of the system.

[0040] Polarization beam splitting: If the system uses a display that requires polarization modulation, such as LCOS, this prism 2 can be used as a polarization beam splitting prism to separate the illumination light from the imaging reflected light, ensuring the system's light efficiency.

[0041] Changing the propagation path: Presetting appropriate angles and positions for the image beam to enter the subsequent lens groups, namely the second optical element group 3 and the first optical element group 4, is an important step for the efficient and correct transmission of the entire optical path.

[0042] The projection optical system provided in this application embodiment also includes an aperture stop 01. The aperture stop 01 is disposed on the object side of the first optical element group 4, that is, at the end of the optical path of the projection optical system. It performs the following functions: Controlling light transmission: The size of its aperture determines the width of the light beam passing through the system, which directly affects the system's relative illumination and image brightness.

[0043] Limiting the depth of field: As the aperture stop of the system, its position and size together determine the depth of field range of the system.

[0044] As an optical reference: In optical design and system integration, the plane containing aperture 01 is often used as a physical and optical reference plane for the system. For example, the total length of the system is often defined as the distance from this plane to the image plane. It is also a critical reference point for the coupling of the outgoing beam into subsequent components such as optical waveguides.

[0045] Based on the above technical solution, the projection optical system of this application brings the following beneficial effects: By adopting an off-axis optical design, the need to tilt the entire lens for optical path refraction is fundamentally avoided, greatly reducing the space and weight occupied by the optical engine in the temples or frame of AR glasses, providing key technical support for AR glasses to achieve a form closer to ordinary glasses.

[0046] The active modulation of the emission angles of the second optical element group 3 pairs enables the image beam to be coupled more efficiently into subsequent optical waveguide devices and other components, improving the overall light efficiency of the projection optical system. This means that users can see a brighter image at the same display brightness, or that the display power consumption can be reduced while meeting the same brightness requirements, which helps to extend the device's battery life.

[0047] Despite its compact structure, the projection optics system maintains high resolution, low distortion, and low dispersion imaging performance across the entire field of view through the correction of off-axis aberrations by the second optical element group 3. This is specifically manifested in a high modulation transfer function (MTF) value, small dot pattern blur, and controllable grid distortion, thereby ensuring that users obtain a clear, realistic, and distortion-free visual experience.

[0048] The projection optical system of this application has a short total length (e.g., TTL≤14mm) and a small telecentricity (Tele<1°). These characteristics make it easier for the emitted beam to be efficiently coupled with the optical waveguide device in the AR glasses, reducing the difficulty of system integration and improving the overall product reliability and performance consistency.

[0049] See some examples in this application. Figure 1 , Figure 7 and Figure 12 The off-axis lens in the first optical element group 4 that satisfies 2≤a≤5 has a non-rotationally symmetric thickness distribution, and its thinnest region is located at the lower edge of the lens. The thickness distribution is used to enable the image beam to achieve spatial off-axis folding relative to the system optical axis.

[0050] In this example of the application, the off-axis lens in the first optical element group 4 that satisfies the thickness ratio 2≤a≤5, such as... Figure 1 , Figure 7 and Figure 12 The first lens 41 shown exhibits a clearly non-rotationally symmetric thickness distribution. Specifically, the thickness of the lens varies non-uniformly at different radial positions, with its thinnest region located at the lower edge of the lens. This specific thickness distribution is a direct structural characteristic of the asymmetric surface shape employed by the lens to achieve an off-axis optical path.

[0051] From an optical principle perspective, this asymmetrical thickness distribution corresponds to an asymmetrical power distribution in the lens. When the image beam from the display 1 passes through this off-axis lens, the upper edge (thicker region) and the lower edge (thinnest region) of the lens exert different deflection effects on the light, creating a synergistic light control effect. This effect ultimately manifests as a controllable, spatial deflection of the entire image beam's propagation path relative to the system's principal optical axis, thereby efficiently achieving spatial off-axis deflection within the projection optical system.

[0052] This design transforms the traditional solution of tilting the entire lens assembly to change the direction of light in projection optics systems into achieving this through the optical structure of a single lens. This shift eliminates the additional space occupied by tilted lens assemblies from the root of optical design, providing a crucial path and technical guarantee for the fundamental miniaturization and compactness of the projection optics system in space-constrained devices such as AR glasses.

[0053] See some examples in this application. Figure 2 The two surfaces of the off-axis lens form an included angle θ between their central tangents, and satisfy: 4°≤θ≤40°.

[0054] In this example of the application, the off-axis lens (such as...) Figure 1 , Figure 7 and Figure 12 The first lens 41 shown in the diagram forms an angle θ between the central tangents of its two surfaces, with the value range limited to 4°≤θ≤40°. This angle θ is a key parameter characterizing the spatial attitude and optical properties of the off-axis lens, reflecting the relative tilt relationship between the two main optical surfaces of the lens in space.

[0055] The included angle θ and the asymmetric thickness distribution together constitute the core characteristics of off-axis lenses. The two work together to precisely control the spatial deflection behavior of light beams as they pass through the lens. By limiting the included angle θ within the aforementioned range, sufficient optical path deflection capability is ensured to replace the traditional tilting scheme of lens groups, while avoiding aberration deterioration and manufacturing difficulties caused by excessive tilting.

[0056] In fact, in this application, the two surfaces of the off-axis lens (see...) Figure 2 The included angle θ formed between the central tangents of the first optical surface 411 and the second optical surface 412 shown in the figure can satisfy 0°≤θ≤40°.

[0057] Through extensive optical simulations and image quality balance analysis, this application determined a preferred range of 4° to 40°. The lower limit of 4° ensures basic beam deflection capability, providing the necessary optical functional foundation for system miniaturization; while the upper limit of 40° effectively controls the complexity of the off-axis optical path, ensuring that the resulting asymmetric aberrations can be effectively corrected by the second optical element group 3, thus achieving a compact structure while maintaining imaging quality.

[0058] In specific embodiments, the included angle θ can be specifically taken as 4°, 18.7°, or 35.8°, etc., all of which are within the preferred range. A reasonable included angle design also brings advantages in manufacturing processes. By avoiding extreme tilt angles, the thickness distribution of the lens is optimized, improving processability and production yield.

[0059] In summary, controlling the included angle θ within the range of 4° to 40° is an important technical means for this application to achieve the best balance between system miniaturization, ensuring high image quality, and ensuring good process feasibility.

[0060] See some examples in this application. Figure 1 , Figure 7 and Figure 12 The second optical element group 3 contains at least three off-axis optical surfaces.

[0061] In this example of the application, see Figure 1 , Figure 7 and Figure 12 The second optical element group 3 is characterized by containing at least three off-axis optical surfaces. Here, an off-axis optical surface refers to an optical surface (including a refractive surface and a reflective surface) whose optical center of action or surface symmetry axis has a definite eccentric, tilted or asymmetrical surface shape distribution relative to the principal optical axis of the system, so that its optical path control function does not have rotational symmetry about the principal optical axis.

[0062] This structural design is the core of the entire projection optical system's high-performance aberration correction. Because the off-axis design of the first optical element group 4 introduces a large number of non-rotationally symmetric off-axis aberrations (such as astigmatism, field curvature, and coma), traditional coaxial symmetric optical surfaces cannot effectively compensate for them. In this case, the second optical element group 3, by configuring multiple off-axis optical surfaces, constructs a correction capability sufficient to match the aforementioned spatial distribution of asymmetric aberrations. Each off-axis optical surface can be considered an independent asymmetric phase modulator. By precisely controlling parameters such as the curvature, tilt, eccentricity, and aspheric coefficient of each optical surface, they collectively generate wavefront compensation with equal amplitude but opposite phase to the aberrations introduced by the first optical element group 4, thereby achieving high-definition imaging across the entire field of view.

[0063] The design of the second optical element group 3 in this application example enables precise asymmetric aberration correction: multiple off-axis optical surfaces (at least three off-axis optical surfaces) provide ample design freedom to perform directional and precise correction of non-rotational symmetric aberrations unique to off-axis optical architectures, which is impossible for traditional coaxial systems, ensuring that the system is compact without sacrificing image quality.

[0064] The design of the second optical element group 3 in this application example can also improve the system's light efficiency and imaging uniformity: through the coordinated design of each off-axis surface, the emission angle of the image beam can be optimized and modulated simultaneously, improving its coupling efficiency with subsequent optical waveguides and other components, and enhancing the illumination uniformity of the entire image plane, thereby comprehensively improving the system's light energy utilization and visual experience.

[0065] In addition, the requirement of at least three off-axis optical surfaces ensures redundancy and flexibility in correction capabilities, enabling optical designers to achieve a better balance between different performance indicators (such as MTF, distortion, and chromatic aberration), and enhances the robustness of projection optical systems to external factors such as manufacturing tolerances and temperature changes, thereby improving the mass productionability and performance consistency of products.

[0066] In some examples of this application, the total optical power φ of the projection optical system satisfies the following relationship with the optical power φ1 of the first optical element group 4 and the optical power φ2 of the second optical element group 3: 0.5≤|φ1-φ2| / φ≤2.

[0067] In this example of the application, a clear constraint relationship is proposed for the optical power distribution of the projection optical system: the total optical power φ of the system satisfies the relationship 0.5≤|φ1-φ2| / φ≤2 with respect to the optical power φ1 of the first optical element group and the optical power φ2 of the second optical element group. This relationship defines the optical power distribution ratio of the two core optical components at the system level and is a key design criterion to ensure that the system maintains excellent imaging quality while achieving off-axis functionality.

[0068] Optical power, as a physical quantity characterizing the ability of an optical element to converge or diverge light, has specific design significance in the projection optical system of this application. The optical power constraint relationship in this example ensures a proper optical power balance between the first optical element group 4 (primarily responsible for off-axis optical path deflection) and the second optical element group 3 (primarily responsible for aberration correction and optical path modulation). When the value of |φ1-φ2| / φ is within the range of 0.5 to 2, it indicates that the optical power distribution between the two element groups has reached an optimal synergistic state: it avoids functional overlap and image quality loss caused by excessively close power levels, and also prevents optical performance imbalance caused by excessive power differences.

[0069] The beneficial effects of the optical power constraint relationship in this example are mainly reflected in three aspects: First, by maintaining an appropriate optical power difference ratio, the first optical element group 4 is ensured to have sufficient optical path control capability to achieve effective off-axis turning, while the second optical element group 3 has sufficient optical correction capability to compensate for the corresponding aberrations; Second, the parameter design in this example balances the optical power distribution inside the projection optical system, enabling the projection optical system to maintain good image plane flatness and small field curvature while achieving off-axis function; Finally, the reasonable optical power allocation enhances the projection optical system's tolerance to manufacturing tolerances and assembly errors, improving the manufacturability and performance consistency of the product.

[0070] In some examples of this application, the total length TTL of the projection optical system satisfies: TTL≤14mm, where TTL is the distance from the surface of the aperture 01 to the light-emitting surface of the display 1 in the optical axis direction of the system.

[0071] The projection optical system of this application has a total length TTL ≤ 14mm, which achieves system compactness. This size ensures that the entire projection optical system has an extremely short axial dimension, enabling it to be integrated into devices with extremely demanding space requirements, such as the temples of AR glasses, thus supporting the thinning and lightening of end products and wearing comfort.

[0072] This compact structure allows the projection optical engine to be embedded as a miniaturized module within the limited space of an AR optical display device, resolving the main contradiction between high-performance optical design and industrial design, and improving the feasibility and ergonomics of the product.

[0073] While achieving a short overall length, this application demonstrates that the entire projection optical system can still maintain excellent imaging quality through the synergistic effect of the aforementioned off-axis architecture and aberration correction design, proving that this size limitation is a key design achievement that successfully balances miniaturization and high performance.

[0074] See some examples in this application. Figure 1 , Figure 7 and Figure 12 The first optical element group 4 consists of only one off-axis lens; the second optical element group 3 consists of three or four lenses.

[0075] In this example of the application, by limiting the first optical element group 4 to consist of only a single off-axis lens, a significant simplification of the system architecture is achieved. This design, while ensuring the core function of off-axis optical path deflection, greatly simplifies the optical structure, effectively compresses the overall optical length and volume, and lays a solid foundation for the integration of the system in confined spaces such as AR glasses.

[0076] By configuring the second optical element group 3 with three or four lenses, sufficient optical correction capability is provided while controlling system complexity. This configuration can effectively compensate for asymmetric aberrations introduced by off-axis optical paths and can also achieve precise modulation of the beam angle, thus achieving an optimized balance between high image quality and high light efficiency in a compact structure.

[0077] This application controls the total number of lenses in the projection optics system to four to five, significantly improving engineering feasibility while meeting optical performance requirements. This design reduces the system's assembly sensitivity and tolerance requirements, which helps improve production yield and control manufacturing costs, thereby enhancing the overall product competitiveness of the solution and achieving an optimal balance between miniaturization, high performance, and manufacturability.

[0078] See some examples in this application. Figure 1 The off-axis lens in the first optical element group 4 is the first lens 41, and its thickness ratio a is 3.3; the second optical element group 3 is composed of a second lens 31, a third lens 32, a fourth lens 33 and a fifth lens 34 arranged sequentially from the aperture 01 side to the display 1 side; wherein, the two surfaces of the second lens 31 and the image side surface of the third lens 32 are both off-axis optical surfaces.

[0079] See Figure 1 The two surfaces of the first lens 41 are respectively Figure 1 The first optical surface 411 and the second optical surface 412 shown are provided. The first optical surface 411 is the side surface of the first lens 41 near the aperture 01, and the second optical surface 412 is the side surface of the first lens 41 near the display 1.

[0080] See Figure 1 The two surfaces of the second lens 31 are respectively Figure 1 The third optical surface 311 and the fourth optical surface 312 shown are provided. The third optical surface 311 is the side surface of the second lens 31 near the aperture 01, and the fourth optical surface 312 is the side surface of the second lens 31 near the display 1.

[0081] See Figure 1 The two surfaces of the third lens 32 are respectively Figure 1 The fifth optical surface 321 and the sixth optical surface 322 shown are provided. The fifth optical surface 321 is the surface of the third lens 32 near the aperture 01, and the sixth optical surface 322 is the surface of the third lens 32 near the display 1.

[0082] exist Figure 1 In the projection optical system shown, the three off-axis optical surfaces in the second optical element group 3 are the third optical surface 311, the fourth optical surface 312, and the sixth optical surface 322, respectively.

[0083] See Figure 1 The two surfaces of the fourth lens 33 are respectively Figure 1 The seventh optical surface 331 and the eighth optical surface 332 shown are provided. The seventh optical surface 331 is the side surface of the fourth lens 33 near the aperture 01, and the eighth optical surface 332 is the side surface of the fourth lens 33 near the display 1.

[0084] See Figure 1 The two surfaces of the fifth lens 34 are respectively Figure 1The ninth optical surface 341 and the tenth optical surface 342 shown are provided. The ninth optical surface 341 is the surface of the fifth lens 34 near the aperture stop 01, and the tenth optical surface 342 is the surface of the fifth lens 34 near the display 1.

[0085] This application provides a specific implementation scheme for a projection optical system, which achieves a comprehensive optimization of miniaturization, high image quality, and good manufacturability through the following design: First, the projection optical system employs a unique off-axis architecture to achieve miniaturization. The first optical element group 4 consists of a single off-axis lens (first lens 41), with an optimized thickness-to-thin ratio α of 3.3. This design integrates the spatial deflection function of the optical path into a single lens, replacing the traditional approach of tilting the entire lens group at the optical architecture level. This directly eliminates the additional space occupied by tilted installation and is the core technical means to achieve the compact goal of a total system length TTL ≤ 4mm.

[0086] Secondly, the projection optical system ensures image quality through a carefully configured aberration correction scheme. The second optical element group 3 adopts a four-element design. By setting two surfaces of the second lens 31 and the image-side surface of the third lens 32 as off-axis optical surfaces, a powerful asymmetric aberration correction capability is constructed, effectively compensating for off-axis aberrations introduced by the off-axis design. The imaging performance of the system is verified by the attached figures: Figure 4 The MTF curve shows that the MTF value is greater than 0.4 across the entire field of view at a spatial frequency of 70 lp / mm. Figure 5 The field distortion map shows that the grid distortion is controlled within 6%, achieving high-definition and low-distortion imaging effect.

[0087] Finally, the projection optics system improves manufacturability through a reasonable configuration of the number of lenses. The total number of five lenses, while meeting optical performance requirements, effectively controls system complexity, reduces sensitivity and tolerance requirements during assembly and adjustment, and lays a solid foundation for improving assembly yield and ensuring consistency and reliability in mass production.

[0088] This example demonstrates a good balance between system miniaturization, high performance and mass production through a configuration of one off-axis pivot and four aberration correction elements.

[0089] See some examples in this application. Figure 7The off-axis lens in the first optical element group 4 is the first lens 41, and its thickness ratio a is 2.3; the second optical element group 3 is composed of a second lens 31, a third lens 32 and a fourth lens 33 arranged sequentially from the aperture side to the display 1 side; wherein, the image side surface of the second lens 31 and the two surfaces of the third lens 32 are both off-axis optical surfaces.

[0090] and Figure 1 The optical architectures of the projection optical systems shown are different. Figure 7 In the projection optical system shown, only three lenses are used in the second optical element group, namely Figure 7 The second lens 31, the third lens 32, and the fourth lens 33 are shown in the figure.

[0091] This application provides an example, see [link to example]. Figure 7 By employing an optimized configuration of one off-axis deflector and three aberration correction elements, a significant breakthrough has been achieved in the compactness of projection optical systems. The first lens 41 adopts a thickness-to-thinness ratio design of 2.3, which further optimizes the lens structure while ensuring effective optical path deflection. Combined with the second optical element group 3, which is simplified to a three-element design, the total number of lenses in the system is controlled to four, resulting in a total system length TTL of only 8.3mm. This demonstrates excellent space compression and provides an ideal solution for integration in AR devices with extremely limited space.

[0092] Regarding imaging performance, this example utilizes three carefully configured off-axis optical surfaces, including the image-side surface of the second lens 31 and two surfaces of the third lens 32. (See [link to relevant documentation]). Figure 7 It maintains strong aberration correction capabilities despite a limited number of lenses. Test data validates its excellent performance: see [link to test data]. Figure 9 , Figure 9 The MTF curves show a full-field MTF value better than 0.35 at a spatial frequency of 70 lp / mm; see [link to relevant documentation]. Figure 10 , Figure 10 The distortion diagram shows that mesh distortion is strictly controlled. See also... Figure 8 , Figure 8 The maximum value of the dot plot is less than 5μm, ensuring that the projection optical system can obtain clear, accurate, and high-quality imaging across the entire field of view.

[0093] Figure 7 The optical architecture design of the projection optics system shown also brings about economic improvements. The configuration of four lenses simplifies the system structure and reduces raw material costs and assembly complexity.

[0094] See Figure 12The three off-axis optical surfaces of the second optical element group 3 are: the surface of the second lens 31 near the display 1, namely the fourth optical surface 312, the two surfaces of the third lens 32, namely the fifth optical surface 321 and the sixth optical surface 322.

[0095] See some examples in this application. Figure 12 The off-axis lens in the first optical element group 4 is the first lens 41, and its thickness ratio a is 4; the second optical element group 3 is composed of a second lens 31, a third lens 32 and a fourth lens 33 arranged sequentially from the aperture side to the display 1 side; wherein, the image side surface of the second lens 31, the two surfaces of the third lens 32 and the two surfaces of the fourth lens 33 are all off-axis optical surfaces.

[0096] This example of the application achieves a significant improvement in system compactness by optimizing optical design parameters. While maintaining the second optical element group 3 as a three-lens structure, the thickness-to-thinness ratio of the first lens 41 is increased to 4. This design, while ensuring the off-axis folding function of the optical path, further reduces the total length (TTL) of the projection optical system to 8mm by optimizing the lens shape and optical power distribution, demonstrating a more superior space compression effect and providing reliable technical support for the development of ultra-thin AR devices.

[0097] In terms of image quality, this example constructs a more complete aberration correction system by setting all five optical surfaces of the three lenses in the second optical element group 3 as off-axis optical surfaces. This design enables the projection optical system to have stronger asymmetric aberration control capabilities. Specific performance characteristics are as follows: Figure 14 The MTF curves show that the MTF value remains at an excellent level at a spatial frequency of 70 lp / mm; Figure 15 The distortion diagram confirms that imaging distortion has been effectively suppressed, while the chromatic aberration along the vertical axis has been controlled within a very small range; Figure 13 The dot plot shows that its maximum value is less than 6 μm. These test results fully demonstrate that the system can provide clear, accurate, and high-quality imaging across the entire field of view.

[0098] In summary, this example employs an off-axis lens with a thickness-to-thin ratio of 4, combined with a three-element corrective lens group featuring five off-axis optical surfaces, to create a unique optical architecture. Building upon the compact advantages of previous examples, this design further enhances image quality by increasing the number of off-axis surfaces, fully demonstrating the flexible adaptability and technological advantages of this application under varying performance requirements.

[0099] See Figure 12The five off-axis optical surfaces of the second optical element group 3 are: the surface of the second lens 31 near the display 1, namely the fourth optical surface 312; the two surfaces of the third lens 32, namely the fifth optical surface 321 and the sixth optical surface 322; and the two surfaces of the fourth lens 33, namely the seventh optical surface 331 and the eighth optical surface 332.

[0100] In some examples of this application, the telecentricity Tele of the projection optical system satisfies Tele < 1°, where Tele is the exit angle of the main ray of the projection optical system from the display 1.

[0101] The low telecentricity design ensures that the main ray emitted from the projection optics system enters the coupling region of the optical waveguide device at a near-perpendicular angle, greatly optimizing the matching degree between the beam and the optical waveguide. This significantly reduces energy loss caused by angular mismatch, directly improving the light energy utilization of the projection optics system, which is of great value for power-constrained AR optical display devices (such as AR glasses).

[0102] By optimizing the telecentricity, the projection optics system achieves consistency in the incident angle of the principal rays across the image plane. This not only effectively suppresses edge illumination attenuation and color drift, but also ensures uniform brightness and color performance across the entire display, thereby significantly enhancing the visual experience.

[0103] The excellent telecentricity also makes it easier for the emitted beam of the projection optics system to work in conjunction with subsequent optical components, significantly reducing the integration difficulty of the optical engine. This characteristic ensures the compact design of the overall system and strongly supports the continued development of AR optical display devices towards thinner and lighter designs.

[0104] In summary, the telecentricity design with a Tele < 1° plays an irreplaceable role in achieving high luminous efficiency, excellent image quality, and good manufacturability, and is of great significance for improving the overall performance of projection optical systems.

[0105] The projection optical system of this application will be described in detail below through Examples 1 to 3.

[0106] Example 1 The projection optical system provided in Embodiment 1 has the following optical architecture: Figure 1 As shown, the projection optical system includes, in sequence along the optical path: display 1, prism 2, second optical element group 3, first optical element group 4, and aperture 01; The display 1 is used to emit image beams; The second optical element group 3 consists of a second lens 31, a third lens 32, a fourth lens 33, and a fifth lens 34 arranged sequentially from the aperture 01 side to the display 1 side; wherein, the third optical surface 311, the fourth optical surface 312, and the sixth optical surface 322 are three off-axis optical surfaces; The first optical element group 4 includes an off-axis lens, which is a first lens 41 with a thickness ratio a of 3.3. An angle θ is formed between the central tangent of the object side surface (first optical surface 411) and the image side surface (second optical surface 412) of the first lens 41, and θ is 18.7°.

[0107] Please refer to Table 1 for the optical parameter table of the projection optical system provided in this embodiment 1.

[0108] Table 1

[0109] In this embodiment 1, the optical power φ1 of the first optical element group 4, the optical power φ2 of the second optical element group 3, and the total optical power φ of the projection optical system are shown in Table 2.

[0110] Table 2

[0111] The total length (TTL) of the projection optical system provided in this embodiment 1 is 14 mm.

[0112] The performance of the projection optical system provided in Embodiment 1 is described as follows: See Figure 3 , Figure 3 This is a dot plot in Embodiment 1. A dot plot refers to a pattern formed by the dispersion of light rays emanating from a single point. Due to aberrations, the intersection points of these rays with the image plane are no longer concentrated at a single point, but rather form a diffuse pattern scattered over a certain range. This pattern is used to evaluate the imaging quality of the projection optical system. In Embodiment 1, the maximum value of the image point in the dot plot is less than 4 μm.

[0113] See Figure 4 , Figure 4 This is the modulation transfer function (MTF curve) diagram of this embodiment 1. It characterizes the imaging sharpness of the optical system by the contrast of black and white line pairs. In this embodiment 1, the MTF is >0.4 at the full field of view of 70 lp / mm.

[0114] See Figure 5 , Figure 5 This is the mesh distortion diagram for Embodiment 1. In Embodiment 1, the mesh distortion is less than 6%.

[0115] See Figure 6 , Figure 6The transverse chromatic aberration of this embodiment 1, also known as magnification chromatic aberration, mainly refers to the difference between the focal positions of blue light and red light on the image plane when a polychromatic principal ray from the object side is emitted as multiple rays due to dispersion in the refraction system. In this embodiment 1, the maximum chromatic aberration value is less than 10 μm.

[0116] Example 2 The projection optical system provided in Embodiment 2 has the following optical architecture: Figure 7 As shown, the projection optical system includes, in sequence along the optical path: display 1, prism 2, second optical element group 3, first optical element group 4, and aperture 01; The display 1 is used to emit image beams; The second optical element group 3 consists of a second lens 31, a third lens 32, and a fourth lens 33 arranged sequentially from the aperture 01 side to the display 1 side; wherein the fourth optical surface 312, the fifth optical surface 321, and the sixth optical surface 322 are off-axis optical surfaces.

[0117] The first optical element group 4 includes an off-axis lens, which is a first lens 41 with a thickness ratio a of 2.3. An angle θ is formed between the central tangents of the first optical surface 411 and the second optical surface 412 of the first lens 41, and θ is 35.8°.

[0118] Please refer to Table 3 for the optical parameter table of the projection optical system provided in this embodiment 2.

[0119] Table 3

[0120] In this embodiment 2, the optical power φ1 of the first optical element group 4, the optical power φ2 of the second optical element group 3, and the total optical power φ of the projection optical system are shown in Table 4.

[0121] Table 4

[0122] The total length (TTL) of the projection optical system provided in this embodiment 2 is 8.3 mm.

[0123] The performance of the projection optical system provided in Embodiment 2 is described as follows: See Figure 8 , Figure 8 This is the dot plot of Embodiment 2. A dot plot refers to a pattern formed by the dispersion of light rays emanating from a single point across the image plane due to aberrations. These rays no longer converge at a single point after passing through the optical system, but instead create a diffuse pattern scattered over a certain range. This pattern is used to evaluate the imaging quality of the projection optical system. In Embodiment 2, the maximum value of the image point in the dot plot is less than 5 μm.

[0124] See Figure 9 , Figure 9 This is the modulation transfer function (MTF curve) diagram of this embodiment 2. It characterizes the imaging sharpness of the optical system by the contrast of black and white line pairs. In this embodiment 2, the MTF is >0.35 at the full field of view of 70 lp / mm.

[0125] See Figure 10 , Figure 10 This is the mesh distortion diagram for Embodiment 2. In Embodiment 2, the mesh distortion is less than 6%.

[0126] See Figure 11 , Figure 11 The transverse chromatic aberration of this embodiment 2, also known as magnification chromatic aberration, mainly refers to the difference between the focal positions of blue light and red light on the image plane when a polychromatic principal ray from the object side is emitted as multiple rays due to dispersion in the refraction system. In this embodiment 2, the maximum chromatic aberration value is less than 10 μm.

[0127] Example 3 The projection optical system provided in Embodiment 3 has the following optical architecture: Figure 12 As shown, the projection optical system includes, in sequence along the optical path: display 1, prism 2, second optical element group 3, first optical element group 4, and aperture 01; The display 1 is used to emit image beams; The second optical element group 3 consists of a second lens 31, a third lens 32, and a fourth lens 33 arranged sequentially from the aperture 01 side to the display 1 side; wherein the fourth optical surface 312, the fifth optical surface 321, the sixth optical surface 322, the seventh optical surface 331, and the eighth optical surface 332 are off-axis optical surfaces.

[0128] The first optical element group 4 includes an off-axis lens, which is a first lens 41 with a thickness ratio a of 2.3. An angle θ is formed between the central tangents of the first optical surface 411 and the second optical surface 412 of the first lens 41, and θ is 4°.

[0129] Please refer to Table 5 for the optical parameter table of the projection optical system provided in this embodiment 3.

[0130] Table 5

[0131] For the optical power φ1 of the first optical element group 4, the optical power φ2 of the second optical element group 3, and the total optical power φ of the projection optical system in this embodiment 3, please refer to Table 6.

[0132] Table 6

[0133] The total length (TTL) of the projection optical system provided in this embodiment 3 is 8 mm.

[0134] The performance of the projection optical system provided in Embodiment 3 is described as follows: See Figure 13 , Figure 13 This is the dot plot of Embodiment 3. A dot plot refers to a pattern formed by the dispersion of light rays emanating from a single point. Due to aberrations, the intersection points of these rays with the image plane are no longer concentrated at a single point, but rather form a diffuse pattern scattered over a certain range. This pattern is used to evaluate the imaging quality of the projection optical system. In Embodiment 3, the maximum value of the image point in the dot plot is less than 6 μm.

[0135] See Figure 14 , Figure 14 This is the modulation transfer function (MTF curve) diagram of this embodiment 3. It characterizes the imaging sharpness of the optical system by the contrast of black and white line pairs. In this embodiment 3, the MTF is >0.4 at the full field of view of 70 lp / mm.

[0136] See Figure 15 , Figure 15 This is the mesh distortion diagram for Embodiment 3. In Embodiment 3, the mesh distortion is less than 6%.

[0137] See Figure 16 , Figure 16 The transverse chromatic aberration of this embodiment 3, also known as magnification chromatic aberration, mainly refers to the difference between the focal positions of blue light and red light on the image plane when a polychromatic principal ray from the object side is emitted as multiple rays due to dispersion in the refraction system. In this embodiment 3, the maximum chromatic aberration value is less than 10 μm.

[0138] According to another embodiment of this application, an AR optical display device is provided, the AR optical display device comprising: an optical waveguide device and a projection optical system as described above, wherein the emitted light beam is coupled into the optical waveguide device via the aperture 01.

[0139] The specific implementation of the AR optical display device in this application can refer to the various embodiments of the light guide device described above. Therefore, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0140] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0141] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A projection optical system, characterized in that, Along the optical path, the following are included in sequence: Display (1), used to emit image beams; Prism (2); The second optical element group (3) includes at least three lenses; A first optical element group (4) includes at least one off-axis lens; and, Aperture (01); The first optical element group (4) is used to realize the off-axis reversal of the optical path, and the thickness ratio a of at least one off-axis lens satisfies 2≤a≤5, wherein the thickness ratio a is the ratio of the thickness of the thickest region to the thickness of the thinnest region of the off-axis lens; The second optical element group (3) is used to correct off-axis aberrations and modulate the emission angle.

2. The projection optical system according to claim 1, characterized in that, The off-axis lens in the first optical element group (4) that satisfies 2≤a≤5 has a non-rotationally symmetric thickness distribution, and its thinnest region is located at the lower edge of the lens. The thickness distribution is used to enable the image beam to achieve spatial off-axis folding relative to the system optical axis.

3. The projection optical system according to claim 2, characterized in that, The two surfaces of the off-axis lens form an included angle θ between their central tangents, and satisfy the condition: 4°≤θ≤40°.

4. The projection optical system according to any one of claims 1-3, wherein the second optical element group (3) comprises at least three off-axis optical surfaces.

5. The projection optical system according to claim 1, characterized in that, The total optical power φ of the projection optical system satisfies the following relationship with the optical power φ1 of the first optical element group (4) and the optical power φ2 of the second optical element group (3): 0.5≤|φ1-φ2| / φ≤2.

6. The projection optical system according to claim 1, characterized in that, The total length TTL of the projection optical system satisfies: TTL≤14mm, where TTL is the distance from the surface of the aperture (01) to the light-emitting surface of the display (1) in the direction of the optical axis of the system.

7. The projection optical system according to claim 6, characterized in that, The first optical element group (4) consists of only one off-axis lens; The second optical element group (3) consists of three or four lenses.

8. The projection optical system according to claim 7, characterized in that, The off-axis lens in the first optical element group (4) is the first lens (41) with a thickness ratio a of 3.3; The second optical element group (3) consists of a second lens (31), a third lens (32), a fourth lens (33) and a fifth lens (34) arranged sequentially from the aperture (01) side to the display (1) side; wherein, the two surfaces of the second lens (31) and the image-side surface of the third lens (32) are off-axis optical surfaces.

9. The projection optical system according to claim 7, characterized in that, The off-axis lens in the first optical element group (4) is the first lens (41) with a thickness ratio a of 2.3; The second optical element group (3) consists of a second lens (31), a third lens (32) and a fourth lens (33) arranged sequentially from the aperture (01) side to the display (1) side; wherein the image side surface of the second lens (31) and the two surfaces of the third lens (32) are both off-axis optical surfaces.

10. The projection optical system according to claim 7, characterized in that, The off-axis lens in the first optical element group (4) is the first lens (41), and its thickness ratio a is 4; The second optical element group (3) consists of a second lens (31), a third lens (32) and a fourth lens (33) arranged sequentially from the aperture (01) side to the display (1) side; wherein, the image side surface of the second lens (31), the two surfaces of the third lens (32) and the two surfaces of the fourth lens (33) are all off-axis optical surfaces.

11. The projection optical system according to claim 1, characterized in that, The telecentricity Tele of the projection optical system satisfies: Tele < 1°, where Tele is the exit angle of the main ray of the projection optical system from the display (1).

12. An AR optical display device, characterized in that, include: Optical waveguide devices; as well as The projection optical system as described in any one of claims 1-11, wherein the outgoing beam is coupled into the optical waveguide device via the aperture (01).

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