Projection light machine, optical projection system and AR optical display device

Abstract

The embodiment of the invention discloses a projection light machine, an optical projection system and AR optical display equipment. The projection light machine comprises a projection lens; the projection lens comprises a bonding lens, the bonding lens comprises a second lens and a third lens which are arranged along the same optical axis and are bonded with each other, the bonding surface where the second lens and the third lens are bonded with each other is an aspheric surface, and the bonding surface does not have a retroflex surface; the curvature of the surface, away from the third lens, of the second lens is K1, the curvature of the gluing face where the second lens and the third lens are glued is K2, the curvature of the surface, away from the second lens, of the third lens is K3, the total effective focal length of the gluing lens is f, and (K1 + K2 + K3) / f is larger than or equal to 0.05 and smaller than or equal to 0.3.

Description

Technical Field

[0001] The present application belongs to the field of optical display technology. Specifically, the present application relates to a projection optical machine, an optical projection system and an AR optical display device. Background Art

[0002] With the rise of the concept of the metaverse, AR glasses have received widespread attention as a key hardware carrier. The key to the popularity of AR glasses lies in their miniaturization and lightweight design. As the core component of AR glasses, the miniaturization of projection optical machines has become an important trend in the current technological development. Optical machines based on μLED (full name MicroLED) technology are considered to be the ultimate choice in the industry because of their simple structure, small size and great potential for display performance development. However, there are problems in the design of traditional AR lenses that are difficult to completely eliminate aberrations and chromatic aberrations, which affects the image quality. Therefore, the development of new lens structures has become the key to improving the optical performance of projection lenses. Summary of the invention

[0003] The purpose of this application is to provide a new technical solution for a projection optical machine, an optical projection system and an AR optical display device.

[0004] According to a first aspect of the present application, an embodiment of the present application provides a projection optical machine, the projection optical machine comprising a projection lens;

[0005] The projection lens comprises a cemented lens, wherein the cemented lens comprises a second lens and a third lens arranged along the same optical axis and cemented to each other, wherein the cemented surface between the second lens and the third lens is an aspherical surface, and there is no anti-curved surface on the cemented surface;

[0006] The curvature of the surface of the second lens away from the third lens is K1, the curvature of the bonding surface where the second lens and the third lens are bonded to each other is K2, the curvature of the surface of the third lens away from the second lens is K3, and the total effective focal length of the bonded lens is f, 0.05≤(K1+K2+K3) / |f|≤0.3.

[0007] Optionally, the center thickness of the second lens is T2, the optical effective aperture of the second lens is L2, and 0.25≤T2 / L2≤0.45;

[0008] The central thickness of the third lens is T3, the optical effective aperture of the third lens is L3, and 0.1≤T3 / L3≤0.3.

[0009] Optionally, the Abbe number of the second lens is v2, the Abbe number of the third lens is v3, and |v2-v3|>20.

[0010] Optionally, the refractive index of the second lens is n2, the refractive index of the third lens is n3, and n2 / n3>1.5.

[0011] Optionally, the second lens and the third lens are both aspherical lenses, and the optical power of the cemented lens is positive.

[0012] Optionally, the projection lens further includes a first lens and a fourth lens, the cemented lens is located between the first lens and the fourth lens, the first lens is located on a side close to the second lens, and the fourth lens is located on a side close to the third lens;

[0013] The first lens, the second lens and the fourth lens have positive optical power, and the third lens has negative optical power.

[0014] Optionally, the first lens is a meniscus lens, the second lens is a biconvex lens, the third lens is a biconcave lens, and the fourth lens is a meniscus lens.

[0015] Optionally, the total effective focal length EFL of the projection lens is: 5 mm <EFL<12mm。

[0016] Optionally, the effective focal length of the first lens is f1,4mm <f1<12mm;

[0017] The effective focal length of the second lens is f2,1 mm <f2<7mm;

[0018] The effective focal length of the third lens is f3, -8mm <f3<-0.8mm;

[0019] The effective focal length of the fourth lens is f4,8mm <f4<80mm。

[0020] Optionally, the center thickness of the first lens is T1, 0.3mm<T1<1mm;

[0021] The center thickness of the second lens is T2, 0.5mm<T2<1.5mm;

[0022] The central thickness of the third lens is T3, 0.25mm<T3<1mm;

[0023] The central thickness of the fourth lens is T4, 0.3 mm<T4<1.2 mm.

[0024] Optionally, the projection optical machine further includes a color combining prism and an image source;

[0025] The projection lens and the image source are respectively arranged on the periphery of the color combining prism, wherein the projection lens is located on the light emitting side of the color combining prism;

[0026] A stop is arranged on the side of the projection lens away from the color combining prism.

[0027] Optionally, the aperture is a front aperture of the projection optical machine, the first lens is close to the aperture, and the fourth lens is far from the aperture;

[0028] The air interval between the first lens and the aperture is A0, 0≤A0<3mm;

[0029] The air interval between the first lens and the second lens is A1, 0.08mm≤A1<1mm;

[0030] The air interval between the second lens and the third lens is A2, A2=0;

[0031] The air interval between the third lens and the fourth lens is A3, 0.3mm≤A3<3mm;

[0032] The air gap between the fourth lens and the color combining prism is A4, 0.1mm≤A4<1mm.

[0033] Optionally, the curvature radius of the surface of the first lens close to the aperture is R1, 1mm<R1<10mm; the curvature radius of the surface of the first lens close to the second lens is R2, R2<30mm;

[0034] The curvature radius of the surface of the second lens close to the first lens is R3, 1mm<R3<10mm; the curvature radius of the bonding surface of the second lens and the third lens is R4, -10mm<R4<200mm; the curvature radius of the surface of the third lens close to the fourth lens is R6, 0.8mm<R6<8mm;

[0035] The curvature radius of the surface of the fourth lens close to the third lens is R7, -10mm<R7<50mm; the curvature radius of the surface of the fourth lens close to the color combining prism is R8, -10mm<R8<-1mm.

[0036] Optionally, the image source is a Micro LED, and the size of each pixel on the image source is a panel pixel, 2μm<panel pixel<5μm;

[0037] The image height H of the image source is: 0<H≤6mm.

[0038] According to a second aspect of the present application, an embodiment of the present application provides an optical projection system, wherein the projection light system comprises:

[0039] The projection optical machine as described in the first aspect; and

[0040] An optical waveguide sheet, used for transmitting the projection light emitted by the projection optical machine to a target position for imaging;

[0041] Wherein, the distance between the exit pupil position of the projection optical machine and the entrance pupil position of the optical waveguide sheet is 2 mm to 5 mm.

[0042] According to a third aspect of the present application, an embodiment of the present application provides an AR optical display device, wherein the AR optical display device includes the optical projection system as described in the second aspect.

[0043] One beneficial effect of the embodiments of the present application is:

[0044] According to the projection optical machine proposed in the embodiment of the present application, the cemented lens in the projection lens is formed by the second lens and the third lens being cemented together, and the cemented surface is an aspherical surface. Compared with the spherical lens, the aspherical lens can more effectively correct the on-axis and off-axis aberrations and improve the imaging quality. By applying the aspherical surface to the cemented lens, the vertical axis chromatic aberration and the on-axis and off-axis aberrations can be reduced at the same time, and the optical performance of the lens can be significantly improved. Moreover, there is no reverse curved surface on the cemented surface of the cemented lens. This design helps to avoid the generation of additional aberrations and further improve the imaging quality. At the same time, the design without reverse curved surface is conducive to the gluing process of the lens, ensuring that the lens surface after gluing is tightly fitted, thereby enhancing the stability and durability of the lens.

[0045] In the present application, the optical properties of the cemented lens are optimized by controlling the proportional relationship between the curvatures (K1, K2, K3) of the three surfaces (the surface of the second lens away from the third lens, the cemented surface, and the surface of the third lens away from the second lens) of the cemented lens and the total effective focal length f of the cemented lens (0.05≤(K1+K2+K3) / |f|≤0.3). This design helps to reduce optical aberrations and improve the clarity and resolution of imaging.

[0046] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0048] Figure 1 One of the structural schematic diagrams of the projection optical machine provided in the embodiment of the present application;

[0049] Figure 2 The second structural schematic diagram of the projection optical machine provided in the embodiment of the present application;

[0050] Figure 3 A schematic diagram of the structure of the projection optical machine provided in Example 1 of the present application;

[0051] Figure 4 for Figure 3 The MTF diagram of the projection lens in the projection optical machine shown;

[0052] Figure 5 for Figure 3 The optical distortion diagram of the projection lens in the projection optical machine shown;

[0053] Figure 6 for Figure 3 The through-focus MTF diagram of the projection lens in the projection optical machine shown;

[0054] Figure 7 for Figure 3 Relative illumination diagram of the projection lens in the projection optical machine shown;

[0055] Figure 8 for Figure 3 The vertical axis chromatic aberration diagram of the projection lens in the projection optical machine shown;

[0056] Fig. 9 A schematic diagram of the structure of a projection optical machine provided in Example 2 of the present application;

[0057] Fig.10 for Fig. 9 The MTF diagram of the projection lens in the projection optical machine shown;

[0058] Fig.11 for Fig. 9 The optical distortion diagram of the projection lens in the projection optical machine shown;

[0059] Fig.12 for Fig. 9 The through-focus MTF diagram of the projection lens in the projection optical machine shown;

[0060] Fig.13 for Fig. 9 Relative illumination diagram of the projection lens in the projection optical machine shown;

[0061] Fig.14 for Fig. 9 The vertical axis chromatic aberration diagram of the projection lens in the projection optical machine is shown.

[0062] Description of reference numerals:

[0063] 1. Aperture; 2. Projection lens; 21. First lens; 211. First surface; 212. Second surface; 22. Second lens; 221. Third surface; 222. Fourth surface; 23. Third lens; 231. Fifth surface; 232. Sixth surface; 24. Fourth lens; 241. Seventh surface; 242. Eighth surface; 3. Color combining prism; 4. Image source. DETAILED DESCRIPTION

[0064] 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 of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0065] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0066] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0067] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0068] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0069] The following is a detailed description of the projection optical machine, optical projection system and AR optical display device provided in the embodiments of the present application in conjunction with the accompanying drawings.

[0070] According to an embodiment of the present application, a projection optical machine is provided. Figure 1 and Figure 2 , the projection optical machine includes a projection lens 2; the projection lens 2 includes a cemented lens, the cemented lens includes a second lens 22 and a third lens 23 arranged along the same optical axis and cemented to each other, the cemented surface where the second lens 22 and the third lens 23 are cemented to each other is an aspheric surface, and there is no anti-curved surface on the cemented surface; the curvature of the surface of the second lens 22 away from the third lens 23 is K1, the curvature of the cemented surface where the second lens 22 and the third lens 23 are cemented to each other is K2, the curvature of the surface of the third lens 23 away from the second lens 22 is K3, the total effective focal length of the cemented lens is f, 0.05≤(K1+K2+K3) / |f|≤0.3.

[0071] The projection optical machine provided in the embodiment of the present application introduces a cemented lens in its projection lens, and the cemented surface of the cemented lens is an aspheric surface. This design combines the advantages of the aspheric lens in reducing on-axis and off-axis aberrations, and the role of the cemented lens in reducing vertical axis chromatic aberration, thereby improving the overall imaging quality of the projection optical machine. In other words, the projection lens provided in the embodiment of the present application, based on the use of the aspheric cemented lens, effectively reduces the vertical axis chromatic aberration and on-axis and off-axis aberrations, and significantly improves the clarity and imaging quality of the projected image.

[0072] In an embodiment of the present application, the projection lens includes the above-mentioned cemented lens, and the air gap between the mutually cemented lenses is zero. This design not only simplifies the projection lens structure, but also helps to reduce the interference of light during propagation, thereby further improving the clarity of imaging.

[0073] In the present application, an aspheric cemented lens is introduced into the projection lens. This design effectively reduces on-axis and off-axis aberrations, and reduces vertical axis chromatic aberration, so that the projection optical machine can output higher quality images and meet the user's requirements for clarity. In addition, the design of the aspheric cemented lens contributes to the miniaturization and lightness of the overall structure of the projection optical machine, which is in line with the current market demand trend for portable and highly integrated products.

[0074] In the embodiments of the present application, an important bonding surface design is described: there is no reverse curved surface on the bonding surface. The bonding surface is designed to have no reverse curved surface. This feature helps to avoid the introduction of additional aberrations during the lens bonding process and ensure the imaging quality. At the same time, the design without reverse curved surface simplifies the processing difficulty of the lens and improves the yield rate of the lens. A more specific analysis is as follows:

[0075] First, it helps to improve the image quality:

[0076] The presence of a reverse curved surface (or a surface with a sudden change in concave or convex curvature) may introduce additional aberrations, thus affecting the image quality. By avoiding the presence of a reverse curved surface on the bonding surface, aberrations can be further reduced, the clarity and contrast of the image can be improved, and the projection optical machine can output high-quality images.

[0077] Second, it is conducive to the smooth progress of the gluing process:

[0078] When there is no reverse curve on the bonding surface, the lens can more easily achieve close bonding during the bonding process, reducing the air gap or poor bonding problems that may be caused by irregular curves. This directly improves the overall quality and stability of the bonded lens and ensures that the optical performance of the lens is not affected.

[0079] Third, reduce the processing technology of the lens:

[0080] The design without reverse curved surface on the bonding surface means that the surface shape of the lens is more regular and smooth, which helps to reduce the difficulty of lens processing and improve production efficiency. At the same time, it avoids the complex surface processing process, reduces processing errors, and improves the manufacturing accuracy of the lens.

[0081] In addition, when the reverse curved surface is subjected to external forces, due to its discontinuous surface shape, it is more likely to produce stress concentration, affecting the mechanical stability of the lens. The design of the bonding surface without reverse curved surface helps to improve the mechanical strength and durability of the lens. In the long-term use process, this design can reduce the risk of lens deformation or damage caused by stress concentration, thereby extending the service life of the projection light machine.

[0082] In this example of the present application, by ensuring that there is no reverse curved surface on the cemented surface of the cemented lens, not only the imaging quality is improved, but also the manufacturing process is simplified and the structural stability of the cemented lens is enhanced. This design detail reflects the comprehensive consideration of the overall performance of the projection optical machine, and provides more reliable support for the development and application of AR smart glasses.

[0083] In the embodiment of the present application, for the cemented lens, a specific constraint condition is introduced regarding the proportional relationship between the three surface curvatures K1, K2, and K3 and the total effective focal length f of the cemented lens, namely, 0.05≤(K1+K2+K3) / |f|≤0.3. This realizes the control of the optical properties of the lens. This optimization helps to reduce optical aberrations and improve imaging quality. The specific analysis is as follows:

[0084] By controlling the proportional relationship between the curvature of each surface in the cemented lens and the total effective focal length of the cemented lens, the optical properties of the cemented lens can be more effectively managed. This constraint helps to reduce aberrations and thus improve image quality. In particular, for aspheric lenses, reasonable control of the curvature distribution of the surface can significantly improve its ability to modulate light, allowing light to be more accurately focused after passing through the lens, forming a clear, high-contrast image.

[0085] See also Figure 2 The three surfaces of the cemented lens are the non-cemented surface of the second lens 22 (i.e., the third surface 221), the cemented surface of the second lens 22 and the third lens 23 (i.e., the Figure 2The fourth surface 222 and the fifth surface 231 shown in the figure) and the non-glued surface of the third lens 23 (i.e., the sixth surface 232). The reasonable distribution of the curvatures of these three surfaces helps to reduce the risk of deformation of the glued lens due to stress concentration. The stability of the lens is crucial to maintaining the long-term optical performance of the system. In the present application, by optimizing the proportional relationship between the curvature of each surface in the glued lens (which is a relatively core lens in the projection lens of the present application) and the total focal length of the glued lens, the mechanical strength of the glued lens can be enhanced, thereby improving the stability of the entire projection lens 2.

[0086] The constraints proposed in this example of the present application also provide guidelines for the manufacturing process of the lens, which helps to accurately control the curvature parameters of the lens during the production process. This can not only improve the processing accuracy of the lens, but also reduce the scrap rate and improve production efficiency. At the same time, due to the direct relationship between the curvature parameter and the focal length of the lens, it is easier to control the focal length of the lens by adjusting the curvature.

[0087] The projection optical machine proposed in the embodiment of the present application has the following beneficial effects:

[0088] (1) Improved imaging quality: The use of aspheric doublet lenses significantly reduces vertical chromatic aberration and on-axis and off-axis aberrations, making the image clearer. This is especially important for applications that require high-precision imaging, such as augmented reality glasses.

[0089] (2) Enhanced lens stability: The bonding surface design without reverse curves improves the tight fit of the lens during the bonding process and reduces the air gap or poor bonding problems that may be caused by irregular curves, thereby enhancing the mechanical stability and durability of the lens.

[0090] (3) Optimizing optical power distribution: By precisely controlling the curvature and focal length ratio of the lens, balanced optical power distribution is achieved, allowing light to smoothly transition between lenses.

[0091] (4) Lightweighting of the entire projection optical machine: The design of this application not only improves the imaging quality, but also takes into account the miniaturization and lightweighting requirements of the projection optical machine. By optimizing the structure and parameters of the lens, it helps to achieve a compact design of the overall optical system and meet the development trend of portable optical display devices.

[0092] In some examples of this application, see Figure 1 and Figure 2 The center thickness of the second lens 22 is T2, the optical effective aperture of the second lens 22 is L2, 0.25≤T2 / L2≤0.45; the center thickness of the third lens 23 is T3, the optical effective aperture of the third lens 23 is L3, 0.1≤T3 / L3≤0.3.

[0093] In this example of the present application, the design of the cemented lens is further optimized, especially by controlling the proportional relationship between the center thickness of the second lens 22 and the third lens 23 and the optical effective aperture, a significant improvement in lens performance is achieved, thereby achieving an improvement in the optical performance of the entire cemented lens.

[0094] For the second lens 22, the ratio of its center thickness T2 to the optical effective aperture L2 is 0.25≤T2 / L2≤0.45. For the third lens 23, the ratio of its center thickness T3 to the optical effective aperture L3 is 0.1≤T3 / L3≤0.3.

[0095] By precisely controlling the ratio of the center thickness of the two glued lenses (i.e., the second lens 22 and the third lens 23) to the optical effective aperture, the optical power of the entire projection optical machine can be more reasonably distributed without sacrificing the imaging quality. This optimization helps to reduce the tolerance sensitivity of each lens, thereby improving the manufacturing yield and stability of the projection lens.

[0096] The ratio of the center thickness of the lens to the optical effective aperture has a direct impact on the image quality. Following the above ratio constraints can ensure that the projection lens can maintain good imaging consistency in various fields of view, reduce aberrations and distortion, and thus provide a clearer and more accurate projection image. This is of great significance for improving the overall imaging effect of the projection optical machine.

[0097] While maintaining imaging performance, reasonable lens thickness design can also help reduce the overall volume and weight of the projection lens, which is crucial for optical display products such as AR smart glasses that pursue portability and comfortable wearing experience.

[0098] A reasonable design of the ratio of center thickness to optical effective aperture helps to enhance the mechanical strength and stability of the lens and reduce the risk of lens deformation or damage due to stress concentration. This is crucial to maintaining the long-term stability of the lens' optical performance.

[0099] In addition, from the perspective of optimizing lens processing and assembly, by precisely controlling the ratio of the center thickness of the lens to the optical effective aperture, it is possible to ensure that the lens processing difficulty is moderate, neither too complicated nor prone to errors. This helps to improve the yield rate and processing efficiency of the lens, and is also beneficial to the subsequent assembly process, ensuring the precise fit between the various components.

[0100] It can be seen that in this application, by accurately controlling the proportional relationship between the center thickness of the second lens 22 and the third lens 23 in the cemented lens and the optical effective aperture, not only the processing, assembly and performance stability of the lens are optimized, but also the imaging quality is further improved, providing strong support for the miniaturization, lightweight and high performance of the projection optical machine.

[0101] In some examples of the present application, the Abbe number of the second lens 22 is v2, the Abbe number of the third lens 23 is v3, and |v2-v3|>20.

[0102] In the present application, regarding the cemented lens in the projection lens 2, its composition includes a second lens 22 and a third lens 23 that are cemented to each other. With respect to the material selection of the second lens 22 and the third lens 23, it is stipulated that the difference between their Abbe numbers v2 and v3 should be greater than 20, that is, |v2-v3|>20. This constraint condition is intended to significantly improve the achromatic function of the cemented aspheric lens by optimizing the dispersion characteristics of the lens material.

[0103] The Abbe number is an important parameter to measure the dispersion characteristics of optical materials. It reflects the difference in the refractive index of the material for light of different wavelengths.

[0104] In the design of the cemented lens provided in the present application, by selecting two materials with large differences in Abbe numbers to respectively manufacture the second lens 22 and the third lens 23, the two materials can have different dispersion characteristics for light of different wavelengths. When the two lenses are cemented together, their dispersion differences can be effectively compensated, thereby significantly reducing vertical axis chromatic aberration and other aberrations caused by dispersion. This improvement in achromatic aberration capability is an important advantage of cemented aspheric lenses in terms of imaging quality compared to conventional single lenses.

[0105] By precisely controlling the Abbe number differences of the lens materials, it is possible to ensure that the cemented aspheric lens maintains excellent imaging performance at different wavelengths. This not only reduces the color edge effect, but also improves the clarity of the image. This technical effect is particularly important for application scenarios that require high-precision imaging, such as augmented reality glasses.

[0106] In some examples of the present application, the refractive index of the second lens 22 is n2, the refractive index of the third lens 23 is n3, and n2 / n3>1.5.

[0107] In the cemented lens of the present application, a specific proportional relationship is set for the refractive index of the second lens 22 and the third lens 23, that is, the ratio of the refractive index n2 of the second lens to the refractive index n3 of the third lens is greater than 1.5 (n2 / n3>1.5). This constraint condition is intended to ensure that the aspheric cemented lens can achieve maximum capability in modulating light by optimizing the refractive indexes of the two lenses.

[0108] The refractive index is a physical quantity that describes the speed at which light propagates in a medium. It is also an important indicator for measuring the ability of a lens to control the direction of light. In an optical system, a lens with a high refractive index can better bend light so that it propagates along a predetermined path.

[0109] In the present application, by setting a larger refractive index difference between the second lens 22 and the third lens 23, the light can undergo a more significant change in direction when passing through the cemented lens composed of the two lenses, thereby enhancing the modulation ability of the aspheric lens on the light. This is crucial to improving the resolution and clarity of the imaging system. Enhancing the modulation ability of the aspheric lens on the light means that the light can be more accurately focused to the predetermined position after passing through the lens, forming a clearer image. This helps to reduce aberrations and distortions and improve the optical performance of the entire projection lens. In application scenarios such as augmented reality (AR) glasses, this technical effect has an important impact on improving user experience and visual effects.

[0110] In summary, by setting a larger refractive index ratio (n2 / n3>1.5) between the second lens 22 and the third lens 23, the present application effectively enhances the light modulation capability of the aspheric cemented lens, thereby improving the imaging quality, enhancing the design flexibility and promoting technological innovation. This technical effect is of great significance for improving the overall performance of the projection optical machine and meeting the diverse application requirements.

[0111] In some examples of the present application, both the second lens 22 and the third lens 23 are aspherical lenses, and the optical power of the cemented lens is positive.

[0112] In the projection lens of the embodiment of the present application, the second lens 22 and the third lens 23 are both designed as aspherical lenses, and are tightly combined into a cemented lens through a specific "thermal bonding" process, and the cemented lens has positive optical power. This design choice is conducive to enhancing the optical performance of the entire projection lens, and even the entire projection optical machine.

[0113] Compared with spherical lenses, aspherical lenses have a higher degree of freedom in optical design and can better correct aberrations. By designing the second lens 22 and the third lens 23 as aspherical surfaces and gluing them together as a whole, the propagation path of light passing through the lens can be more effectively controlled, significantly reducing on-axis and off-axis aberrations, thereby improving imaging quality.

[0114] Aspherical lenses combined with bonding technology can not only reduce aberrations, but also reduce the position deviation of light of different wavelengths on the imaging surface, namely vertical axis chromatic aberration, by accurately matching parameters such as lens material and thickness. This is crucial to improving color reproduction and imaging clarity.

[0115] In this example of the present application, the focal power of the cemented lens is positive, which helps to optimize the focal power distribution of the entire projection lens 2. The cemented aspheric lens with positive focal power allows for more flexible distribution of focal power in the overall projection lens design. Since the aspheric lens can control the direction of light more accurately, higher optical performance can be achieved while maintaining the miniaturization of the projection lens.

[0116] By using aspheric cemented lenses, the number of lenses in the projection lens can be reduced or the lens combination can be simplified without sacrificing image quality, thereby reducing the size and weight of the projection lens and meeting the needs of miniaturization and lightweight for portable optical display devices such as AR glasses.

[0117] Although the processing of aspheric lenses is relatively complex, once they are glued together to form an integral lens, their handling in the projection lens assembly becomes relatively simple. In addition, due to the use of a positive optical power design strategy, the tolerance sensitivity of the entire projection lens is reduced, which helps to improve production yield.

[0118] In some examples of this application, see Figure 1 and Figure 2 The projection lens 2 also includes a first lens 21 and a fourth lens 24, the cemented lens is located between the first lens 21 and the fourth lens 24, the first lens 21 is located on a side close to the second lens 22, and the fourth lens 24 is located on a side close to the third lens 23; wherein the first lens 21, the second lens 22 and the fourth lens 24 have positive optical power, and the third lens 23 has negative optical power.

[0119] In this example of the present application, the design of the projection lens 2 is achieved through four lenses, namely, a first lens 21, a second lens 22, a third lens 23 and a fourth lens 24, wherein the second lens 22 and the third lens 23 form a cemented lens, and their optical powers are cleverly distributed, thereby achieving a significant technical effect. Specifically:

[0120] (1) Balanced distribution of optical power:

[0121] By making the first lens 21, the second lens 22 and the fourth lens 24 have positive power, and the third lens 23 has negative power, balanced distribution of power is achieved. This layout not only ensures smooth transition of light between the lenses, but also makes the optical correction task borne by each lens relatively balanced, without the need for extreme optical parameters.

[0122] (2) Application and aberration control of cemented aspheric lenses:

[0123] The cemented aspheric lens composed of the second lens 22 and the third lens 23 is the core component of the projection lens of the present application. By adopting the advanced "thermal bonding" process, the close bonding of the aspheric lens surface is ensured, thereby giving full play to the advantages of the aspheric lens in reducing on-axis and off-axis aberrations. In addition, the structure of the cemented lens also effectively reduces the vertical axis chromatic aberration and improves the overall imaging quality.

[0124] (3) Improved imaging quality:

[0125] Thanks to the introduction of cemented aspheric lenses, the projection lens performs well in color reproduction, contrast, clarity, etc. This feature is crucial for high-precision imaging devices such as augmented reality (AR) glasses, which can bring users a more realistic and immersive visual experience.

[0126] In some examples of the present application, the first lens 21 is a meniscus lens, the second lens 22 is a biconvex lens, the third lens 23 is a biconcave lens, and the fourth lens 24 is a meniscus lens.

[0127] In this example of the present application, the design of the projection lens adopts four specific types of lenses: a meniscus-type first lens 21 , a biconvex second lens 22 , a biconcave third lens 23 , and a meniscus-type fourth lens 24 .

[0128] Among them, the first lens 21 and the fourth lens 24 are meniscus lenses. The design of the meniscus lens helps to provide a smooth optical transition in the light path and reduce unnecessary light reflection and scattering. Using a meniscus lens at the light entrance position of the projection lens 2 can effectively collect and guide the light into the projection lens; and using a meniscus lens at the light exit position can fine-tune the light after the complex light path processing to ensure that the light is projected onto the imaging surface at an ideal angle.

[0129] The second lens 22 is a biconvex lens. As a part of the aspheric lens bonded with the third lens 23, the biconvex design enhances the positive focal length, helps to converge light and reduce spherical aberration. After bonding with the biconcave lens, it can better correct aberration and improve imaging clarity.

[0130] The third lens 23 is a biconcave lens. The biconcave design gives the lens negative focal power, and when used in combination with a biconvex lens (second lens 22), through a precise gluing process, it can effectively correct the image field curvature and reduce the aberrations on and off the axis, especially the field curvature and distortion.

[0131] In the projection lens of the present application, the second lens 22 and the third lens 23 are cemented to form a cemented aspherical lens, which not only significantly reduces the lateral chromatic aberration but also improves the color reproducibility. The cemented design of the biconvex type and the biconcave type enables the full play of the advantages of the aspherical lens, further optimizing the optical performance of the projection lens.

[0132] In this example of the present application, this lens combination method also helps to design a more compact and reasonable lens barrel and AR optical engine module structure, further promoting the mass production and market popularity of the product.

[0133] In some examples of the present application, the total effective focal length EFL of the projection lens 2 is: 5mm < EFL < 12mm.

[0134] In this example of the present application, the total effective focal length (EFL) of the projection lens 2 is set between 5mm and 12mm. This focal length range aims to balance multiple factors such as imaging quality, field of view (FOV), projection lens size, and applicable scenarios.

[0135] A shorter focal length (such as 5mm to 12mm) helps to obtain a wider field of view, which is particularly important in augmented reality (AR) applications because it can provide a broader field of vision, enabling users to naturally integrate into the virtual-reality combined environment. However, an overly short focal length (below 5mm) may increase aberrations and affect the imaging quality.

[0136] Setting the upper limit of the total effective focal length EFL of the projection lens 2 at 12mm leaves sufficient design space for correcting aberrations while ensuring a certain field of view. This focal length range allows for a fine optical design to balance the field of view and imaging quality, ensuring that users can enjoy clear and distortion-free images while obtaining a wide field of vision.

[0137] In portable optical display devices such as AR glasses, the miniaturization and lightweighting of the projection lens are crucial. A shorter effective focal length helps to reduce the physical size and weight of the projection lens, thus meeting the requirements of miniaturizing the projection optical engine therein. By setting the EFL of the projection lens 2 between 5mm and 12mm, a compact design of the projection lens can be achieved while maintaining good imaging performance, thereby realizing the miniaturization of the projection optical engine.

[0138] In some examples of the present application, the effective focal length of the first lens 21 is f1, 4mm < f1 < 12mm; the effective focal length of the second lens 22 is f2, 1mm < f2 < 7mm; the effective focal length of the third lens 23 is f3, -8mm < f3 < -0.8mm; the effective focal length of the fourth lens 24 is f4, 8mm < f4 < 80mm.

[0139] In this example of the present application, the effective focal length ranges of the lenses in the projection lens 2 are described.

[0140] The effective focal length f1 of the first lens 21 is: 4 mm < f1 < 12 mm. As the first lens of the projection lens 2, it is responsible for collecting and initially focusing light ( Figure 1 and Figure 2 the optical path in is the reverse optical path design). The set range of the effective focal length f1 ensures sufficient converging ability while leaving a design margin to accommodate different optical configurations.

[0141] The effective focal length f2 of the second lens 22 is: 1 mm < f2 < 7 mm. The effective focal length f3 of the third lens is: -8 mm < f3 < -0.8 mm. Among them, as part of the cemented aspherical lens, the second lens 22 with a shorter focal length enhances the positive optical power and helps to further converge light. After being cemented with the third lens 23 (negative optical power), the two jointly correct aberrations and improve the imaging quality. The third lens 23, with its negative optical power design, is used to correct field curvature and other off-axis aberrations.

[0142] The effective focal length f4 of the fourth lens 24 is: 8 mm < f4 < 80 mm. The relatively large effective focal length range enables the fourth lens 24 to play a role in finely adjusting the light direction in the optical path, ensuring that the light is projected onto the imaging surface at an ideal angle. In addition, it also helps to reduce the remaining aberrations and improve the imaging clarity.

[0143] In this example of the present application, the effective focal lengths of the four lenses are set. By precisely controlling the effective focal length ranges of the lenses, a reasonable distribution of the optical power is achieved. This distribution method not only optimizes the optical performance but also reduces the tolerance sensitivity of each lens.

[0144] Due to the uniform distribution of the optical power, the influence of each lens on the overall optical performance is dispersed, making it easier for the projection lens to meet the design requirements during the production process. This reduces the extreme dependence on processing accuracy and improves the production stability and yield.

[0145] In some examples of the present application, the central thickness of the first lens 21 is T1, 0.3 mm < T1 < 1 mm; the central thickness of the second lens 22 is T2, 0.5 mm < T2 < 1.5 mm; the central thickness of the third lens 23 is T3, 0.25 mm < T3 < 1 mm; the central thickness of the fourth lens 24 is T4, 0.3 mm < T4 < 1.2 mm.

[0146] The central thickness T1 of the first lens 21 is: 0.3mm<T1<1mm. This constraint ensures that the thickness of the first lens 21 is moderate, neither too thin to increase the processing difficulty and insufficient strength, nor too thick to cause unnecessary material waste and increase the size of the projection lens.

[0147] The central thickness T2 of the second lens 22 is: 0.5 mm < T2 < 1.5 mm. As an important component of the projection lens 2, the second lens 22 has a reasonable thickness which is helpful to balance the optical performance and the manufacturing cost.

[0148] The central thickness T3 of the third lens 23 is: 0.25mm<T3<1mm. The third lens 23 is a lens with a specific optical function (such as a negative optical power biconcave lens), and the precise control of its thickness is crucial to achieve this function. The thinner lens design helps to achieve the miniaturization of the optical machine, but it also needs to ensure sufficient processing accuracy and stability.

[0149] The center thickness T4 of the fourth lens 24 is: 0.3mm<T4<1.2mm. As the last lens in the projection lens 2, the reasonable setting of its thickness has an important influence on the final image quality. At the same time, the thinner lens design also helps to achieve the miniaturization and lightness of the optical machine.

[0150] This example of the present application describes the center thickness of the four lenses that make up the projection lens. By setting a reasonable range of lens center thickness, the processing difficulties and strength problems caused by too thin lenses are avoided, and the unnecessary processing costs and difficulties caused by too thick lenses are also avoided. This helps to improve production efficiency and yield rate.

[0151] In some examples of this application, see Figure 1 and Figure 2 The projection optical machine also includes a color combining prism 3 and an image source 4; the projection lens 2 and the image source 4 are respectively arranged on the periphery of the color combining prism 3, wherein the projection lens 2 is located on the light emitting side of the color combining prism 3; and an aperture 1 is arranged on the side of the projection lens 2 away from the color combining prism 3.

[0152] It should be noted that the structure of the projection optical machine provided in the embodiment of the present application can refer to Figure 1 As shown, the front aperture 1, projection lens 2 (including 4 lenses, including a cemented aspheric lens), color combining prism 3 and image source 4 are placed in sequence along the optical path. In order to facilitate design and evaluation, the optical structure is simplified. The simplified optical structure can be referred to Figure 2 , the color combining prism 3 is equivalent to a cube prism, and the three R / G / B image sources 4 are equivalent to one RGB image source 4.

[0153] The color combining prism 3 is, for example, an Xcube color combining prism, which plays a key role in the entire projection optical machine. It combines the light from different color image sources to form a full-color image. In this example of the present application, the color combining prism 3 is responsible for combining the light from multiple monochromatic image sources 4 into a full-color light beam, see Figure 1 .

[0154] The image source 4 provides the light signal required for AR display, which refers to three monochromatic MicroLEDs (μLED image sources) of R / G / B, which respectively generate red, green and blue light. In applications, these image sources can be controlled by a driving circuit to generate the required image content.

[0155] The projection lens 2 is responsible for receiving the full-color light from the color-combining prism and converging it to the display area of ​​the AR glasses. The design of the projection lens is crucial to the image quality, including clarity, color reproduction, and field of view.

[0156] The aperture 1 is located in front of the projection lens 2 and is used to limit the range of light passing through the projection lens, thereby controlling the aperture size and depth of field of the imaging. The setting of the aperture plays an important role in adjusting the depth of field and imaging quality of the lens.

[0157] The projection optical machine provided in the embodiment of the present application has a compact optical layout. By separately arranging the projection lens 2 and the image source 4 on the periphery of the color combining prism 3, and arranging the projection lens 2 on the light-emitting side of the color combining prism 3, this layout effectively saves space and makes the volume of the entire projection optical machine more compact. This is crucial for miniaturization and lightweighting of projection optical equipment (such as AR glasses, etc.).

[0158] The color combining prism 3 is located between the projection lens 2 and the image source 4, and can efficiently combine monochromatic light from different image sources into a beam of full-color light, thereby ensuring the color richness and restoration of the image display.

[0159] In some examples of the present application, the aperture 1 is the front aperture of the projection optical machine, the first lens 21 is close to the aperture 1, and the fourth lens 24 is far away from the aperture 1; the air gap between the first lens 21 and the aperture 1 is A0, 0≤A0<3mm; the air gap between the first lens 21 and the second lens 22 is A1, 0.08mm≤A1<1mm; the air gap between the second lens 22 and the third lens 23 is A2, A2=0; the air gap between the third lens 23 and the fourth lens 24 is A3, 0.3mm≤A3<3mm; the air gap between the fourth lens 24 and the color combining prism 3 is A4, 0.1mm≤A4<1mm.

[0160] In this example of the present application, the air gap A0 between the aperture 1 and the first lens 21 is: 0≤A0<3mm. This setting limits the minimum distance between the aperture 1 and the first lens 21, avoiding stray light or interference problems caused by too close distance. At the same time, it also provides sufficient space for the assembly of the projection lens 2, facilitating precise adjustment of the position of the aperture to ensure that light passes through the projection lens 2 accurately. This setting also helps to reduce the volume of the front end of the projection lens 2, which is conducive to the miniaturization of the entire projection optical machine.

[0161] In this example of the present application, the air gap A1 between the first lens 21 and the second lens 22 is: 0.08mm≤A1<1mm. By controlling the distance between the first lens 21 and the second lens 22, it is ensured that the light can smoothly enter the second lens 22 after passing through the first lens 21, thereby reducing the loss of light energy. A narrow but reasonable air gap helps to maintain the compactness of the projection lens 2 while ensuring the stability of the optical performance.

[0162] In this example of the present application, the air gap A2 between the second lens 22 and the third lens 23 is 0. This is because the second lens 22 and the third lens 23 are directly glued together without an air gap between them, thus forming a glued aspheric lens to optimize aberration correction and chromatic aberration reduction. The glued lens design helps to improve the imaging quality and optical performance of the projection lens 2, especially in reducing aberration and chromatic aberration.

[0163] In this example of the present application, the air spacing A3 between the third lens 23 and the fourth lens 24 is: 0.3mm≤A3<3mm. The appropriate air spacing allows the light to have enough space to diffuse and re-converge after passing through the third lens, reducing the interference or stray light that may be generated by the lenses being too close. At the same time, this spacing also provides space for fine-tuning the assembly of the projection lens 2, ensuring that the fourth lens can be accurately placed in the imaging light path.

[0164] In this example of the present application, the air gap between the fourth lens 24 and the color combining prism 3 is A4: 0.1mm≤A4<1mm. The distance between the fourth lens 24 and the color combining prism 3 is controlled to ensure that the full-color light can accurately enter the color combining prism for color combining processing. Appropriate spacing also helps to reduce the loss of light during transmission and improve the utilization rate of light energy.

[0165] This example of the present application ensures the stability and rationality of the structure of the projection lens 2 by precisely controlling each air gap, avoiding the degradation of optical performance that may be caused by improper spacing. The compact structural design helps to achieve the miniaturization and lightweight of the optical machine. In addition, the reasonable air gap provides sufficient space and flexibility for the assembly of the projection lens 2, making the assembly process smoother and more precise. It reduces the errors and difficulties that may occur during the assembly process, and improves production efficiency and yield.

[0166] In some examples of the present application, the curvature radius of the surface of the first lens 21 close to the aperture 1 is R1, 1mm<R1<10mm; the curvature radius of the surface of the first lens 21 close to the second lens 22 is R2, R2<30mm;

[0167] The curvature radius of the surface of the second lens 22 close to the first lens 21 is R3, 1mm<R3<10mm; the curvature radius of the bonding surface of the second lens 22 and the third lens 23 is R4, -10mm<R4<200mm; the curvature radius of the surface of the third lens 23 close to the fourth lens 24 is R6, 0.8mm<R6<8mm;

[0168] The curvature radius of the surface of the fourth lens 24 close to the third lens 23 is R7, -10mm<R7<50mm; the curvature radius of the surface of the fourth lens 24 close to the color combining prism 3 is R8, -10mm<R8<-1mm.

[0169] In this example of the present application, see Figure 2 , the curvature radius of the first lens 21 is designed as follows:

[0170] The curvature radius R1 of the surface of the first lens 21 close to the aperture 1, i.e., the first surface 211, is: 1mm<R1<10mm. This constraint ensures that the curvature of the incident surface of the first lens is neither too large nor too small, which is conducive to controlling the angle at which light enters the projection lens 2 and avoiding excessive aberration. The curvature radius R2 of the surface of the first lens 21 close to the second lens 22, i.e., the second surface 212, is: R2<30mm. A larger curvature radius helps to reduce the difficulty of processing while ensuring good imaging quality.

[0171] In this example of the present application, see Figure 2 , the curvature radii of the second lens 22 and the third lens 23 are designed as follows:

[0172] The curvature radius R3 of the surface of the second lens 22 close to the first lens 21, that is, the third surface 221, is: 1mm<R3<10mm. This constraint is conducive to controlling the transmission of light between the first lens 21 and the second lens 22, and maintaining a small aberration.

[0173] The curvature radius R4 of the bonding surface of the second lens 22 and the third lens 23, that is, the fourth surface 222, is: -10mm<R4<200mm. The wide constraint range allows adjustment according to specific optical design requirements while ensuring that the bonding process is moderately difficult.

[0174] The bonding surface of the third lens 23 and the second lens 22 is a fifth surface 231 . The fifth surface 231 has the same curvature radius as the fourth surface 222 . The curvature radius of the fifth surface 231 is defined as R5: −10 mm<R4=R5<200 mm.

[0175] The surface of the third lens 23 close to the fourth lens 24, namely the sixth surface 232, has a curvature radius R6 of: 0.8mm<R6<8mm. This range limits the size of the curvature radius, which helps to control the modulation effect of the lens on light while maintaining a reasonable processing difficulty.

[0176] In this example of the present application, see Figure 2 , the curvature radius of the fourth lens 24 is designed as follows:

[0177] The surface of the fourth lens 24 close to the third lens 23, namely the seventh surface 241, has a curvature radius R7: -10mm<R7<50mm. A moderate curvature radius is conducive to maintaining the imaging performance of the lens without excessively increasing the processing difficulty.

[0178] The surface of the fourth lens 24 close to the color combining prism 3, namely the eighth surface 242, has a curvature radius R8 of: -10mm<R8<-1mm. The setting of a negative curvature radius helps to diverge or converge light, and is adjusted according to specific design to meet imaging requirements.

[0179] In this example of the present application, the radius of curvature of each lens in the projection lens 2 is described. Through reasonable curvature radius constraints, the occurrence of extreme curvature is avoided, making the lens processing process more stable and controllable, and reducing the scrap rate and cost in the production process. Appropriate curvature radius design helps to reduce the aberration and distortion of the lens and improve the imaging clarity and color reproduction of the projection lens. This is crucial for the design of projection optical machines and is directly related to the user's visual experience.

[0180] In some examples of the present application, the image source 4 is a Micro LED, the size of each pixel on the image source 4 is a panel pixel, 2μm<panel pixel<5μm; the image height H of the image source 4 is: 0<H≤6mm.

[0181] The image source 4 is Micro LED (μLED), which is a new display technology based on LED technology, with advantages such as high brightness, high contrast, high resolution and fast response. Using Micro LED as an image source in a projection optical machine can significantly improve the display effect and user experience.

[0182] The size of each pixel on the image source 4 is a panel pixel, and satisfies the condition 2μm<panel pixel<5μm. The selection of this size range is based on the trade-off between display accuracy and manufacturing cost. Smaller pixel size can provide higher resolution and more delicate image quality, but it also increases manufacturing cost and difficulty. Therefore, the selection of this range is intended to control manufacturing cost while maintaining high display quality.

[0183] The image height H of the image source 4 is 0<H≤6mm. This constraint limits the maximum imaging height of the image source, which is crucial for designing a compact and efficient projection optical machine. A smaller image height means that the optical machine can achieve a smaller size and lighter weight while ensuring imaging quality, which is especially important for wearable devices.

[0184] In this application, Micro LED is used as the image source 4, and its high brightness, high contrast and high resolution characteristics can significantly improve the display effect of the projection light machine. This enables users to obtain a clearer and more realistic visual experience when wearing AR glasses.

[0185] Since the projection optical machine is mainly used for imaging in the visible light range, the design of the image source parameters needs to ensure good performance in this wavelength range. By precisely controlling the pixel size and image height, the image source parameters in this application can ensure high-quality imaging effects in the visible light wavelength range.

[0186] According to another embodiment of the present application, an optical projection system is provided, the optical projection system comprising:

[0187] The projection optical machine as described in the first aspect; and

[0188] An optical waveguide sheet, used for transmitting the projection light emitted by the projection optical machine to a target position for imaging;

[0189] Wherein, the distance between the exit pupil position of the projection optical machine and the entrance pupil position of the optical waveguide sheet is 2 mm to 5 mm.

[0190] The optical projection system provided in the embodiment of the present application mainly consists of two parts, which are as follows:

[0191] (1) Projection optical machine: Based on the projection optical machine design in this application, in particular, a 0.13″ μLED single-color μLED chip, an Xcube color-combining prism, and a projection lens 2 including a cemented aspherical lens are used;

[0192] (2) Optical waveguide: used to transmit the projection light emitted by the projection optical machine to the target position for imaging, thereby realizing image transmission and display.

[0193] About the cooperation between projection optical machine and optical waveguide:

[0194] This application points out that the distance between the exit pupil position of the projection optical machine and the entrance pupil position of the optical waveguide is 2mm to 5mm. This design constraint is crucial to the integration and imaging quality of the entire optical projection system. The specific analysis is as follows:

[0195] In the present application, the distance between the exit pupil position of the projection optical machine and the entrance pupil position of the optical waveguide is 2 mm to 5 mm, which helps to reduce the volume of the entire optical projection system, making it more compact, in line with the development trend of miniaturization and lightweight of AR glasses. Moreover, this distance setting can ensure that the energy loss and aberration of light are minimized during the transmission process from the projection optical machine to the optical waveguide, thereby ensuring the clarity and brightness of the image.

[0196] According to another embodiment of the present application, an AR optical display device is provided, and the AR optical display device includes: a housing and the above optical projection system.

[0197] It should be noted that the AR optical display device provided in the embodiment of the present application is, for example, an AR head-mounted display device.

[0198] Furthermore, the AR head mounted display device is, for example, AR smart glasses or an AR smart helmet.

[0199] The specific implementation of the AR optical display device of the embodiment of the present application can refer to the above-mentioned embodiments of the projection optical machine and the optical projection system, so it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0200] The projection optical machine provided in this application is described in detail below through Example 1 and Example 2.

[0201] Example 1

[0202] See also Figure 3 The projection optical machine includes an aperture 1, a projection lens 2, a color combining prism 3 and an image source 4. The projection lens 2 and the image source 4 are respectively arranged around the color combining prism 3. The aperture 1 is a front aperture and is located on a side of the projection lens 2 away from the color combining prism 3.

[0203] The projection lens 2 includes a first lens 21, a second lens 22, a third lens 23 and a fourth lens 24 arranged in sequence, the second lens 22 and the third lens 23 are both aspherical lenses, the second lens 22 and the third lens 23 are glued together to form a glued lens, and the glued surface of the two is an aspherical surface; the first lens 21 is located on one side of the near aperture 1, and the fourth lens 24 is located on one side of the color combining prism 3;

[0204] Among them, the angle between the tangent line at any point on the cemented surface of the cemented lens and the optical axis of the projection lens is α, 45°≤α≤90°; there is no anti-curved surface on the cemented surface of the cemented lens; the Abbe number of the second lens 22 is v2, the Abbe number of the third lens 23 is v3, |v2-v3|>20; the refractive index of the second lens 22 is n2, the refractive index of the third lens 23 is n3, n2 / n3>1.5.

[0205] Among them, the first lens 21 is a meniscus lens with positive optical power, the second lens 22 is a biconvex lens with positive optical power, the third lens 23 is a biconcave lens with negative optical power, and the fourth lens 24 is a meniscus lens with positive optical power; the optical power of the cemented lens composed of the second lens 22 and the third lens 23 is positive.

[0206] The projection lens provided in this embodiment 1 has an optical total length of 9.1 mm, an entrance pupil diameter of 3.3 mm, an F number of 2.5, an effective focal length EFFL of 8.2 mm, and a FOV of 22°;

[0207] The wavelength of the projection light of the projection light machine is set to 455:525:630nm=1:5:3.

[0208] The size of the image source 4 is: 640*480*4μm.

[0209] Table 1 shows the specific optical parameters of the optical projection system of this embodiment 1.

[0210] Table 1

[0211]

[0212]

[0213] The optical performance of the projection optical machine provided in this embodiment 1 can be as follows: Figures 4 to 8 As shown:

[0214] Figure 4 The MTF diagram of the projection lens provided in this embodiment 1 shows that the average MTF of each field of view is greater than 0.63, and the imaging is good;

[0215] Figure 5 The optical distortion diagram of the projection lens provided in this embodiment 1, the optical distortion is less than 0.99%, which meets the imaging quality requirements;

[0216] Figure 6 The defocus MTF diagram of the projection lens provided in this embodiment 1, the defocus range of MTF>0.4 is greater than 0.02mm, and has a large defocus range, which is beneficial to assembly and optical-mechanical stability;

[0217] Figure 7 The relative illumination diagram of the projection lens provided in this embodiment 1 shows that the illumination at the outermost edge relative to the center is greater than 80%, indicating that the image brightness of the projection lens is uniform, the light energy loss at the edge is small, and the utilization rate of the illumination light is high.

[0218] Figure 8 The vertical axis chromatic aberration diagram of the projection lens provided in this embodiment 1 has a vertical axis chromatic aberration value of <2 μm=0.5 pixel size, which meets the imaging requirements of the projection optical machine.

[0219] Example 2

[0220] See also Fig. 9 The optical architecture of the projection light machine shown in this embodiment 2 is the same as the optical architecture of the projection light machine shown in the above-mentioned embodiment 1.

[0221] The projection lens provided in this embodiment 2 has an optical total length of 9.07 mm, an entrance pupil diameter of 3.3 mm, an F number of 2.46, an effective focal length EFFL of 8.1 mm, and a FOV of 22°.

[0222] The wavelength of the projection light is set to 455:525:630nm=1:5:3.

[0223] The size of the image source 4 is: 640*480*4μm.

[0224] Table 2 shows the specific optical parameters of the optical projection system of this embodiment 2.

[0225] Table 2

[0226]

[0227]

[0228] The optical performance of the projection optical machine provided in this embodiment 2 can be as follows: Figures 10 to 14 As shown:

[0229] Fig.10 The MTF diagram of the projection lens provided in this embodiment 2 shows that the average MTF of each field of view is greater than 0.6, and the imaging is good;

[0230] Fig.11 The optical distortion diagram of the projection lens provided in this embodiment 2, the optical distortion is less than 1.2%, which is conducive to image restoration;

[0231] Fig.12 The defocus MTF diagram of the projection lens provided in this embodiment 2, the defocus range of MTF>0.4 is greater than 0.018mm, and has a large defocus range, which is beneficial to assembly and optical-mechanical stability;

[0232] Fig.13 The relative illumination diagram of the projection lens provided in this embodiment 2 shows that the illumination at the outermost edge relative to the center is greater than 80%, indicating that the imaging brightness of the lens of the invention is uniform, the light energy loss at the edge is small, and the utilization rate of the illumination light is high.

[0233] Fig.14 The vertical axis chromatic aberration diagram of the projection lens provided in this embodiment 2 has a vertical axis chromatic aberration of <1 μm, which meets the imaging requirements of the projector.

[0234] The above embodiments focus on 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. Considering the simplicity of the text, they will not be repeated here.

[0235] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A projection optical machine, characterized in that: The projection optical machine comprises a projection lens (2); The projection lens (2) comprises a cemented lens, wherein the cemented lens comprises a second lens (22) and a third lens (23) which are arranged along the same optical axis and cemented to each other, wherein the cemented surface where the second lens (22) and the third lens (23) are cemented to each other is an aspherical surface, and there is no reverse curved surface on the cemented surface; The curvature of the surface of the second lens (22) facing away from the third lens (23) is K1, the curvature of the bonding surface where the second lens (22) and the third lens (23) are bonded to each other is K2, the curvature of the surface of the third lens (23) facing away from the second lens (22) is K3, and the total effective focal length of the bonded lens is f, 0.05≤(K1+K2+K3) / |f|≤0.

3.

2. The projection optical machine according to claim 1, characterized in that: The central thickness of the second lens (22) is T2, the optical effective aperture of the second lens (22) is L2, and 0.25≤T2 / L2≤0.45; The central thickness of the third lens (23) is T3, the optical effective aperture of the third lens (23) is L3, and 0.1≤T3 / L3≤0.

3.

3. The projection optical machine according to claim 2, characterized in that: The Abbe number of the second lens (22) is v2, the Abbe number of the third lens (23) is v3, and |v2-v3|>20.

4. The projection optical machine according to claim 2, characterized in that: The refractive index of the second lens (22) is n2, the refractive index of the third lens (23) is n3, and n2 / n3>1.

5.

5. The projection optical machine according to any one of claims 1 to 4, characterized in that: The second lens (22) and the third lens (23) are both aspherical lenses, and the optical power of the cemented lens is positive.

6. The projection optical machine according to claim 5, characterized in that: The projection lens (2) further comprises a first lens (21) and a fourth lens (24), the cemented lens being located between the first lens (21) and the fourth lens (24), the first lens (21) being located on a side close to the second lens (22), and the fourth lens (24) being located on a side close to the third lens (23); The first lens (21), the second lens (22) and the fourth lens (24) have positive optical power, and the third lens (23) has negative optical power.

7. The projection optical machine according to claim 6, characterized in that: The first lens (21) is a meniscus lens, the second lens (22) is a biconvex lens, the third lens (23) is a biconcave lens, and the fourth lens (24) is a meniscus lens.

8. The projection optical machine according to claim 6, characterized in that: The total effective focal length EFL of the projection lens (2) is: 5 mm <EFL<12mm。 9. The projection optical machine according to claim 6, characterized in that: The effective focal length of the first lens (21) is f1,4 mm <f1<12mm; The effective focal length of the second lens (22) is f2,1 mm <f2<7mm; The effective focal length of the third lens (23) is f3, -8mm <f3<-0.8mm; The effective focal length of the fourth lens (24) is f4,8 mm <f4<80mm。 10. The projection optical machine according to claim 6, characterized in that: The center thickness of the first lens (21) is T1, 0.3 mm < T1 < 1 mm; The central thickness of the second lens (22) is T2, 0.5 mm < T2 < 1.5 mm; The central thickness of the third lens (23) is T3, 0.25 mm < T3 < 1 mm; The central thickness of the fourth lens (24) is T4, 0.3 mm < T4 < 1.2 mm.

11. The projection optical machine according to claim 6, characterized in that: The projection optical machine also includes a color combining prism (3) and an image source (4); The projection lens (2) and the image source (4) are respectively arranged on the peripheral side of the color combining prism (3), wherein the projection lens (2) is located on the light emitting side of the color combining prism (3); A diaphragm (1) is arranged on the side of the projection lens (2) facing away from the color combining prism (3).

12. The projection optical machine according to claim 11, characterized in that: The aperture (1) is a front aperture of the projection optical machine, the first lens (21) is close to the aperture (1), and the fourth lens (24) is far from the aperture (1); The air interval between the first lens (21) and the aperture (1) is A0, 0≤A0<3mm; The air gap between the first lens (21) and the second lens (22) is A1, 0.08 mm ≤ A1 < 1 mm; The air interval between the second lens (22) and the third lens (23) is A2, A2=0; The air interval between the third lens (23) and the fourth lens (24) is A3, 0.3 mm ≤ A3 < 3 mm; The air gap between the fourth lens (24) and the color combining prism (3) is A4, 0.1 mm≤A4<1 mm.

13. The projection optical machine according to claim 12, characterized in that: The curvature radius of the surface of the first lens (21) close to the aperture (1) is R1, 1mm<R1<10mm; the curvature radius of the surface of the first lens (21) close to the second lens (22) is R2, R2<30mm; The curvature radius of the surface of the second lens (22) close to the first lens (21) is R3, 1mm<R3<10mm; the curvature radius of the bonding surface of the second lens (22) and the third lens (23) is R4, -10mm<R4<200mm; the curvature radius of the surface of the third lens (23) close to the fourth lens (24) is R6, 0.8mm<R6<8mm; The curvature radius of the surface of the fourth lens (24) close to the third lens (23) is R7, -10mm<R7<50mm; the curvature radius of the surface of the fourth lens (24) close to the color combining prism (3) is R8, -10mm<R8<-1mm.

14. The projection optical machine according to claim 11, characterized in that: The image source (4) is a Micro LED, and the size of each pixel on the image source (4) is panel pixel, 2 μm<panel pixel<5 μm; The image height H of the image source (4) is: 0<H≤6mm.

15. An optical projection system, characterized in that: include: The projection light machine as claimed in any one of claims 1 to 14; and An optical waveguide sheet, used for transmitting the projection light emitted by the projection optical machine to a target position for imaging; Wherein, the distance between the exit pupil position of the projection optical machine and the entrance pupil position of the optical waveguide sheet is 2 mm to 5 mm.

16. An AR optical display device, characterized in that: include: shell; and The optical projection system of claim 15.

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