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

Abstract

The embodiments of the present application disclose a projection optical machine, an optical projection system and an AR optical display device; the projection optical machine includes a projection lens; the projection lens includes a cemented lens, the cemented lens includes a second lens and a third lens arranged along the same optical axis and cemented to each other, the cemented surface between the second lens and the third lens is aspherical, and there is no reverse curved surface on the cemented surface; the curvature of the surface of the second lens away from the third lens is K1, the curvature of the cemented surface between the second lens and the third lens is K2, the curvature of the surface of the third lens away from the second lens is K3, the total effective focal length of the cemented lens is f, 0.05≤(K1+K2+K3) / |f|≤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 metaverse concept, AR glasses, as a key hardware carrier, have received widespread attention. The key to the popularization of AR glasses lies in their miniaturization and lightweight design. As the core component of AR glasses, the miniaturization of projection optical engines has become a major trend in current technological development. Optical engines based on μLED (full name MicroLED) technology are considered the ultimate choice in the industry due to their simple structure, small size, and great potential for display performance development. However, traditional AR lens designs have problems with aberrations and chromatic aberrations that are difficult to completely eliminate, affecting 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 light 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 engine, the projection optical engine including a projection lens;

[0005] The projection lens includes a cemented lens, the cemented lens including a second lens and a third lens arranged along the same optical axis and cemented to each other, the cemented surface between the second lens and the third lens being aspherical, and no anti-curved surface on the cemented surface;

[0006] The curvature of the surface of the second lens facing away from the third lens is K1, the curvature of the cemented surface between the second lens and the third lens is K2, the curvature of the surface of the third lens facing away from the second lens is K3, and the total effective focal length of the cemented 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 center 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 aspheric 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: 5mm <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 f2,1mm <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, 0.3 mm < T1 < 1 mm;

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

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

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

[0024] Optionally, the projection light engine 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 exit side of the color combining prism;

[0026] A stop is provided 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 away from the aperture;

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

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

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

[0031] The air gap 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, 2 μm<panel pixel<5 μm;

[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 light engine as described in the first aspect; and

[0040] An optical waveguide, 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 cementing the second lens and the third lens together, and the cemented surface is an aspheric surface. Compared with the spherical lens, the aspheric lens can more effectively correct the on-axis and off-axis aberrations and improve the imaging quality. By applying the aspheric 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. In addition, 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 cementing process of the lens, ensuring that the surface of the lens after cementation is tightly fitted, thereby enhancing the stability and durability of the lens.

[0045] This application also optimizes the optical properties of the cemented lens by controlling the ratio between the curvatures (K1, K2, and K3) of the three surfaces of the cemented lens (the surface of the second lens facing away from the third lens, the cemented surface, and the surface of the third lens facing away from the second lens) and the total effective focal length f of the cemented lens (0.05 ≤ (K1 + K2 + K3) / |f| ≤ 0.3). This design helps reduce optical aberrations and improve image clarity and resolution.

[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 This is one of the structural diagrams of the projection optical engine provided in an embodiment of the present application;

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

[0050] Figure 3 A schematic diagram of the structure of the projection optical engine 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] Figure 9 A schematic diagram of the structure of the projection optical engine provided in Example 2 of the present application;

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

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

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

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

[0061] Figure 14 for Figure 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 arrangements 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 disclosure, 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 part of the specification.

[0067] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not 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 like 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 describes in detail the projection light engine, 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 one 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 between the second lens 22 and the third lens 23 is aspherical, 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 between the second lens 22 and the third lens 23 is K2, the curvature of the surface of the third lens 23 away from the second lens 22 is K3, and the total effective focal length of the cemented lens is f, 0.05≤(K1+K2+K3) / |f|≤0.3.

[0071] The projection optical engine provided in the embodiments of the present application incorporates a cemented lens into its projection lens, and the cemented surface of the cemented lens is aspherical. This design combines the advantages of aspheric lenses in reducing on-axis and off-axis aberrations with the role of cemented lenses in reducing vertical axial chromatic aberration, thereby improving the overall imaging quality of the projection optical engine. In other words, the projection lens provided in the embodiments of the present application, based on the use of an aspheric cemented lens, effectively reduces vertical axial chromatic aberration as well as on-axis and off-axis aberrations, significantly improving the clarity and image 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 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 this application, the projection lens incorporates an aspheric doublet lens. This design effectively reduces both on-axis and off-axis aberrations, while also reducing vertical chromatic aberration. This enables the projection machine to output higher-quality images, meeting user requirements for clarity. Furthermore, the aspheric doublet lens design contributes to the miniaturization and lightweighting of the overall projection machine structure, meeting the current market demand for portable, highly integrated products.

[0074] The embodiments of this application describe a key design feature for the bonding surface: the absence of a reversed surface. This design helps avoid the introduction of additional aberrations during lens bonding, ensuring image quality. Furthermore, the absence of a reversed surface simplifies lens manufacturing and improves the yield rate of the lens. A more detailed analysis follows:

[0075] First, it helps improve imaging quality:

[0076] The presence of inverted surfaces (or surfaces with a sudden change in curvature, either concave or convex) can introduce additional aberrations, thus affecting image quality. Avoiding inverted surfaces on the bonded surfaces can further reduce aberrations, improve image clarity and contrast, and ensure high-quality image output from the projector.

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

[0078] When the bonding surfaces do not have reverse curves, the lenses can more easily achieve a tight fit during bonding, reducing air gaps or poor bonding that may be caused by irregular curved surfaces. This directly improves the overall quality and stability of the bonded lens, ensuring that the optical performance of the lens is not affected.

[0079] Third, reduce the lens processing technology:

[0080] The design of no 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] Furthermore, when subjected to external forces, the discontinuous nature of the reverse curved surface can easily lead to stress concentration, which can affect the mechanical stability of the lens. A design without a reverse curved surface helps improve the mechanical strength and durability of the lens. Over long-term use, this design reduces the risk of lens deformation or damage caused by stress concentration, thereby extending the life of the projection light engine.

[0082] In this example, by ensuring that the cemented lens surfaces are free of inverse curves, not only does this improve image quality, but it also simplifies the manufacturing process and enhances the structural stability of the cemented lens. This design detail reflects comprehensive consideration of the overall performance of the projection optical engine, providing more reliable support for the development and application of technologies such as AR smart glasses.

[0083] In the embodiments of this application, a specific constraint on the proportional relationship between the three surface curvatures K1, K2, and K3 and the total effective focal length f of the cemented lens is introduced for the cemented lens: 0.05 ≤ (K1 + K2 + K3) / |f| ≤ 0.3. This achieves control over the optical properties of the lens. This optimization helps reduce optical aberrations and improve imaging quality. A detailed analysis is as follows:

[0084] By controlling the proportional relationship between the curvature of each surface in a cemented lens and its total effective focal length, the optical properties of the cemented lens can be more effectively managed. This constraint helps reduce aberrations, thereby improving image quality. For aspheric lenses in particular, properly controlling the curvature distribution of the surface can significantly enhance their ability to modulate light, allowing light to be more accurately focused after passing through the lens, resulting in clear, high-contrast images.

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

[0086] The constraints proposed in this example also provide guidelines for the lens manufacturing process, helping to precisely control the lens curvature parameters during production. This not only improves lens processing accuracy, but also reduces scrap rates and improves production efficiency. Furthermore, due to the direct correlation between the curvature parameters and the lens focal length, it is easier to control the lens focal length 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 doublets significantly reduces vertical chromatic aberration and on-axis and off-axis aberrations, making images clearer. This is particularly important for applications requiring high-precision imaging, such as augmented reality glasses.

[0089] (2) Enhanced lens stability: The bonding surface design without reverse curved surfaces improves the tight fit of the lens during the bonding process, reduces the air gap or poor bonding problems that may be caused by irregular curved surfaces, and thus enhances 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, a balanced distribution of optical power is achieved, allowing light to transition smoothly between lenses.

[0091] (4) Lightweighting of the entire projection machine: While improving imaging quality, the design of this application also takes into account the need for miniaturization and lightweighting of the projection machine. By optimizing the structure and parameters of the lens, it helps to achieve a compact design of the entire optical system, meeting 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, thereby achieving a significant improvement in lens performance, 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 machine can be more rationally distributed without sacrificing image quality. This optimization helps 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 a lens to its effective optical aperture has a direct impact on image quality. Adhering to these ratio constraints ensures consistent imaging across a wide range of fields of view, minimizing aberrations and distortion, thereby providing clearer and more accurate projection images. This is crucial for improving the overall imaging performance of the projection engine.

[0097] While maintaining imaging performance, proper lens thickness design also helps reduce the overall size and weight of the projection lens, which is crucial for optical display products such as AR smart glasses that strive for portability and a comfortable wearing experience.

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

[0099] Furthermore, from the perspective of optimizing lens processing and assembly, precisely controlling the ratio of the lens's center thickness to its effective optical aperture ensures that the lens's processing difficulty is moderate, neither overly complex nor prone to errors. This helps improve the lens's yield rate and processing efficiency, while also facilitating subsequent assembly by ensuring precise fit between components.

[0100] It can be seen that in this application, by precisely 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 this application, the cemented lens in the projection lens 2 comprises a second lens 22 and a third lens 23 cemented together. The material selection for the second lens 22 and the third lens 23 stipulates that the difference between their Abbe numbers v2 and v3 must be greater than 20, i.e., |v2-v3|>20. This constraint is intended to significantly improve the achromatic performance of the cemented aspheric lens by optimizing the dispersion properties of the lens materials.

[0103] The Abbe number is an important parameter for measuring 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 cemented lens design provided herein, by selecting two materials with significantly different Abbe numbers for the second lens element 22 and the third lens element 23, the two materials exhibit different dispersion characteristics for light of different wavelengths. When the two lenses are cemented together, their dispersion differences are effectively compensated, significantly reducing vertical chromatic aberration and other aberrations caused by dispersion. This improved achromatic aberration capability is a key advantage of cemented aspheric lenses in image quality compared to conventional single lenses.

[0105] By precisely controlling the Abbe number differences in lens materials, the cemented aspheric lens maintains excellent imaging performance at different wavelengths. This not only reduces color fringing but also improves image clarity. This technical effect is particularly important for applications requiring 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 this application, a specific ratio is set for the refractive indices 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 is intended to ensure that the aspheric cemented lens can achieve maximum light modulation ability by optimizing the refractive indices of the two lenses.

[0108] Refractive index is a physical quantity that describes the speed at which light propagates through a medium. It is also an important indicator of a lens's ability to control the direction of light. In an optical system, a lens with a high refractive index can better bend light, causing it to propagate 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 aspheric lens's ability to modulate light. This is crucial for improving the resolution and clarity of the imaging system. Enhancing the aspheric lens's ability to modulate light means that the light can be more accurately focused to a predetermined position after passing through the lens, forming a clearer image. This helps to reduce aberrations and distortion 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 establishing a large refractive index ratio (n2 / n3 > 1.5) between the second lens 22 and the third lens 23, this application effectively enhances the light modulation capability of the aspheric doublet lens, thereby improving image quality, enhancing design flexibility, and promoting technological innovation. This technical effect is of great significance for improving the overall performance of the projection optical engine and meeting diverse application needs.

[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 this embodiment, both the second lens element 22 and the third lens element 23 are designed as aspheric lenses and are tightly bonded together through a specific "thermal bonding" process to form a cemented lens with positive optical power. This design choice helps enhance the optical performance of the entire projection lens and, by extension, the entire projection optical engine.

[0113] Compared to spherical lenses, aspherical lenses offer greater freedom in optical design and can better correct aberrations. By designing both the second lens 22 and the third lens 23 as aspherical surfaces and gluing them together as a single unit, the propagation path of light through the lenses can be more effectively controlled, significantly reducing on-axis and off-axis aberrations, thereby improving image quality.

[0114] Aspheric lenses combined with a bonding process not only reduce aberrations but also, by precisely matching lens materials and thickness, reduce the positional deviation of light of different wavelengths on the imaging surface, known as vertical chromatic aberration. This is crucial for improving color reproduction and image clarity.

[0115] In this example of the present application, the optical power of the cemented lens is positive, which helps optimize the optical power distribution of the entire projection lens 2. The positive optical power of the cemented aspheric lens allows for more flexible optical power distribution in the overall projection lens design. Because the aspheric lens can more precisely control the direction of light, it can achieve higher optical performance 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, meeting the miniaturization and lightweight requirements of portable optical display devices such as AR glasses.

[0117] While aspheric lenses are relatively complex to manufacture, once cemented together to form a monolithic lens, their handling in projection lens assembly becomes relatively simple. Furthermore, the adoption of a positive optical power design reduces the overall projection lens's tolerance sensitivity, helping 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. 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 the use of four lenses: a first lens 21, a second lens 22, a third lens 23, and a fourth lens 24. The second lens 22 and the third lens 23 form a cemented lens, and their optical power is cleverly distributed, achieving significant technical effects. Specifically:

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

[0121] By ensuring that the first lens 21, the second lens 22, and the fourth lens 24 have positive power, while the third lens 23 has negative power, a balanced distribution of optical power is achieved. This layout not only ensures smooth light transition between the lenses, but also ensures that each lens receives a relatively balanced optical correction, eliminating the need for extreme optical parameters.

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

[0123] The cemented aspheric lens, consisting of the second lens element 22 and the third lens element 23, is the core component of the projection lens system. Using an advanced "thermal bonding" process, the aspheric lens surfaces are tightly bonded, fully leveraging their advantages in reducing both on- and off-axis aberrations. Furthermore, the cemented lens structure effectively reduces vertical chromatic aberration, improving overall image quality.

[0124] (3) Improved imaging quality:

[0125] Thanks to the introduction of cemented aspheric lenses, the projection lens performs exceptionally well in terms of color reproduction, contrast, and clarity. This characteristic is crucial for high-precision imaging devices such as augmented reality (AR) glasses, providing users with 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] The first lens 21 and the fourth lens 24 are meniscus lenses. The meniscus lens design helps provide a smooth optical transition in the optical path, reducing unnecessary light reflections and scattering. Using a meniscus lens at the light entrance of the projection lens 2 effectively collects and guides light into the projection lens. Using a meniscus lens at the light exit allows for fine-tuning of the light after a complex optical path, ensuring that the light is projected onto the imaging surface at the ideal angle.

[0129] The second lens 22 is a biconvex lens. As part of a bonded aspheric lens with the third lens 23, its biconvex design enhances positive optical power, helps converge light, and reduces spherical aberration. When bonded with a biconcave lens, it can better correct aberrations and improve image clarity.

[0130] The third lens element 23 is a biconcave lens. The biconcave design gives the lens negative optical power. When used in conjunction with the biconvex lens element (the second lens element 22), through a precise bonding process, it can effectively correct for field curvature and reduce on-axis and off-axis aberrations, especially field curvature and distortion.

[0131] In the projection lens of the present application, the second lens 22 and the third lens 23 are glued together to form a glued aspherical lens, which not only significantly reduces the lateral chromatic aberration but also improves the color reproducibility. The glued 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 - 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 aberration 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 aberration correction while ensuring a certain field of view. This focal length range allows for balancing the field of view and imaging quality through fine optical design, 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 for miniaturization of 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 designed as an inverse optical path). 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 residual aberrations and improve 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 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 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 center 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 processing difficulty and insufficient strength, nor too thick to cause unnecessary material waste and increase the size of the projection lens.

[0147] The center 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 thickness that is reasonably controlled to help balance optical performance and manufacturing costs.

[0148] The central thickness T3 of the third lens 23 is 0.25 mm < T3 < 1 mm. The third lens 23 is a lens with a specific optical function (such as a negative-power biconcave lens), and precise control of its thickness is crucial to achieving this function. While this thin lens design facilitates miniaturization of the optical machine, it also requires sufficient processing accuracy and stability.

[0149] The center thickness T4 of the fourth lens 24 is: 0.3mm < T4 < 1.2mm. As the final lens in the projection lens 2, its thickness is crucial for image quality. A thinner lens design also contributes to the miniaturization and lightweighting 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 for the center thickness of the lenses, the processing difficulties and strength issues caused by lenses that are too thin are avoided, as well as the unnecessary processing costs and difficulties caused by lenses that are too thick. This helps improve production efficiency and yield.

[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; an aperture 1 is provided 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 light machine provided in the embodiment of the present application can refer to Figure 1 As shown in FIG, the optical structure is arranged in the order of the front aperture 1, the projection lens 2 (including 4 lenses, including a cemented aspheric lens), the color combining prism 3 and the image source 4. 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 light 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. Figure 1 .

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

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

[0156] The diaphragm 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 diaphragm plays an important role in adjusting the depth of field and imaging quality of the lens.

[0157] The optical projection engine provided in the embodiments of the present application has a compact optical layout. By separately arranging the projection lens 2 and the image source 4 around 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 entire optical projection engine more compact. This is crucial for achieving miniaturization and lightweighting of optical projection equipment (such as AR glasses).

[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 < 3 mm. 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 a distance. It also provides sufficient space for the assembly of the projection lens 2, facilitating precise adjustment of the aperture position and ensuring that light accurately passes through the projection lens 2. This setting also helps reduce the volume of the front end of the projection lens 2, facilitating the miniaturization of the entire projection optical machine.

[0161] In this example, the air gap A1 between the first lens 21 and the second lens 22 is 0.08 mm ≤ A1 < 1 mm. Controlling the distance between the first lens 21 and the second lens 22 ensures that light can smoothly enter the second lens 22 after passing through the first lens 21, minimizing light energy loss. This narrow but appropriate air gap helps maintain the compactness of the projection lens 2 while ensuring stable optical performance.

[0162] In this example, the air gap A2 between the second lens 22 and the third lens 23 is zero. This is because the second lens 22 and the third lens 23 are directly cemented together, with no air gap between them. This forms a cemented aspheric lens, which optimizes aberration correction and chromatic aberration reduction. This cemented lens design helps improve the imaging quality and optical performance of the projection lens 2, particularly significantly reducing aberrations and chromatic aberrations.

[0163] In this example, the air gap A3 between the third lens 23 and the fourth lens 24 is 0.3mm ≤ A3 < 3mm. This appropriate air gap allows sufficient space for light to diffuse and reconverge after passing through the third lens, reducing interference and stray light that may result from lenses being too close together. This gap also allows for fine-tuning of the projection lens 2 during assembly, ensuring the fourth lens is precisely positioned in the imaging optical path.

[0164] In this example, the air gap between the fourth lens 24 and the color-combining prism 3 is A4: 0.1mm≤A4<1mm. This controlled distance between the fourth lens 24 and the color-combining prism 3 ensures that full-color light can accurately enter the color-combining prism for color processing. This appropriate gap also helps reduce light loss during transmission and improves light energy utilization.

[0165] This example of the present application ensures the structural stability and rationality of projection lens 2 by precisely controlling the air gaps, avoiding the potential degradation of optical performance caused by improper spacing. The compact structural design contributes to the miniaturization and lightweighting of the optical machine. Furthermore, the appropriate air gaps provide ample space and flexibility for assembling projection lens 2, making the assembly process smoother and more precise. This reduces potential errors and difficulties during assembly, improving 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 radius of curvature R1 of the first lens 21's surface near the aperture 1, or first surface 211, is 1 mm < R1 < 10 mm. This constraint ensures that the curvature of the incident light surface of the first lens is neither too large nor too small, which helps control the angle at which light enters the projection lens 2 and avoids excessive aberrations. The radius of curvature R2 of the second surface 212 of the first lens 21's surface near the second lens 22, or second surface 212, is R2 < 30 mm. This larger radius of curvature helps reduce manufacturing complexity 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 between the second lens 22 and the third lens 23, i.e., the fourth surface 222, is: -10mm<R4<200mm. The wide constraint range allows adjustment according to specific optical design requirements while ensuring moderate difficulty of the bonding process.

[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 adjacent to the fourth lens 24, namely the sixth surface 232, has a curvature radius R6 of 0.8 mm < R6 < 8 mm. This range limits the curvature radius, helping to control the lens's light modulation effect while maintaining a reasonable manufacturing 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 of: -10mm<R7<50mm. A moderate curvature radius is conducive to maintaining the imaging performance of the lens while not excessively increasing the processing difficulty.

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

[0179] This example of the present application describes the curvature radius of each lens in the projection lens 2. By properly constraining the curvature radius, extreme curvatures are avoided, making the lens processing more stable and controllable, and reducing scrap rates and costs during the production process. Appropriate curvature radius design helps reduce lens aberrations and distortion, improving the projection lens's image clarity and color reproduction. This is crucial for the design of projection optical engines 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] Image source 4 is Micro LED (μLED), a new display technology based on LED technology that offers advantages such as high brightness, high contrast, high resolution, and fast response. Using Micro LED as an image source in a projection light engine can significantly improve display quality and user experience.

[0182] Each pixel on the image source 4 is a panel pixel, satisfying the condition 2μm < panel pixel < 5μm. This size range was chosen based on a trade-off between display accuracy and manufacturing cost. Smaller pixel sizes provide higher resolution and more detailed image quality, but also increase manufacturing cost and difficulty. Therefore, this range was chosen to maintain high display quality while controlling manufacturing costs.

[0183] The image source 4 has an image height H of 0 < H ≤ 6 mm. This constraint limits the maximum image height of the image source and is crucial for designing compact and efficient projection engines. A smaller image height allows the engine to achieve a smaller size and lighter weight while maintaining image quality, which is particularly important for wearable devices.

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

[0185] Because projection engines are primarily used for imaging within the visible light range, the image source parameters must be designed to ensure good performance within this wavelength range. By precisely controlling pixel size and image height, the image source parameters in this application ensure high-quality imaging within the visible light wavelength range.

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

[0187] The projection light engine as described in the first aspect; and

[0188] An optical waveguide, 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, as follows:

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

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

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

[0194] This application specifies that the distance between the exit pupil of the projection engine and the entrance pupil 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 this application, the distance between the exit pupil of the projection engine and the entrance pupil of the optical waveguide is 2mm to 5mm. This distance helps reduce the volume of the entire optical projection system, making it more compact and in line with the development trend of miniaturization and lightweight AR glasses. Furthermore, this distance setting ensures that energy loss and aberrations are minimized during the transmission of light from the projection engine to the optical waveguide, thereby ensuring image clarity and brightness.

[0196] According to another embodiment of the present application, an AR optical display device is provided, comprising: 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 light 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 engine provided by 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 the 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, which are 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 cemented together to form a cemented lens, and the cemented surface of the second lens 22 and the third lens 23 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] 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, and 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, and |v2-v3|>20; 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.

[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 Example 1 has an optical 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 light engine 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 Example 1 shows that the average MTF of each field of view is greater than 0.63, indicating good imaging.

[0215] Figure 5 This is the optical distortion diagram of the projection lens provided in Example 1. The optical distortion is less than 0.99%, meeting the imaging quality requirements.

[0216] Figure 6 The defocus MTF diagram of the projection lens provided in Example 1 shows that the defocus range with MTF>0.4 is greater than 0.02mm, which has a large defocus range and is beneficial for 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 Figure 9 The optical architecture of the projection light engine shown in this embodiment 2 is the same as the optical architecture of the projection light engine shown in the above 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 light engine provided in this embodiment 2 can be as follows: Figures 10 to 14 As shown:

[0229] Figure 10 The MTF diagram of the projection lens provided in Example 2 shows that the average MTF of each field of view is greater than 0.6, indicating good imaging.

[0230] Figure 11 This is the optical distortion diagram of the projection lens provided in Example 2. The optical distortion is less than 1.2%, which is beneficial for image restoration.

[0231] Figure 12 The defocus MTF diagram of the projection lens provided in Example 2 shows that the defocus range with MTF>0.4 is greater than 0.018 mm, which is beneficial for assembly and optical-mechanical stability.

[0232] Figure 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] Figure 14 The vertical axis chromatic aberration diagram of the projection lens provided in this embodiment 2 has a vertical axis chromatic aberration of less than 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 for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples 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 light machine, characterized in that: The projection optical machine includes a projection lens (2); The projection lens (2) includes a cemented lens, the cemented lens including a second lens (22) and a third lens (23) arranged along the same optical axis and cemented to each other, the cemented surface between the second lens (22) and the third lens (23) being aspherical, and no anti-curved surface exists 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 of the second lens (22) and the third lens (23) 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 light engine according to claim 1, wherein: The center 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 center 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 light engine according to claim 2, wherein: 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 light engine according to claim 2, wherein: 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 light engine according to any one of claims 1 to 4, characterized in that: The second lens (22) and the third lens (23) are both aspheric lenses, and the optical power of the cemented lens is positive.

6. The optical projection machine according to claim 5, wherein: 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 light engine according to claim 6, wherein: 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 optical projection machine according to claim 6, wherein: The total effective focal length EFL of the projection lens (2) is: 5mm <EFL<12mm。 9. The optical projection machine according to claim 6, wherein: 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。 10. The optical projection machine according to claim 6, wherein: The center thickness of the first lens (21) is T1, 0.3mm<T1<1mm; The center thickness of the second lens (22) is T2, 0.5mm<T2<1.5mm; The central thickness of the third lens (23) is T3, 0.25mm<T3<1mm; The center thickness of the fourth lens (24) is T4, 0.3mm<T4<1.2mm.

11. The optical projection machine according to claim 6, wherein: The projection optical machine further 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 provided on the side of the projection lens (2) facing away from the color combining prism (3).

12. The optical projection machine according to claim 11, wherein: 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 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, 0.08 mm ≤ A1 < 1 mm; 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.

13. The optical projection machine according to claim 12, wherein: 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 optical projection machine according to claim 11, wherein: 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 according to any one of claims 1 to 14; and An optical waveguide, 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 according to claim 15.

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