Optical machine lens module and AR optical display device

Abstract

The embodiment of the invention provides an optical machine lens module and AR optical display equipment. The optical machine lens module sequentially comprises a first lens, a second lens, a third lens, a fourth lens, an X-cube color combination prism and a fifth lens from an object side to an image side along an optical axis, the first lens is an aspheric positive lens, the second lens is an aspheric positive lens, the third lens is an aspheric negative lens, the fourth lens is an aspheric positive lens, and the fifth lens is an aspheric negative lens. The total focal length F of the optical machine lens module is more than 4.1 mm and less than 4.8 mm; the focal length f1 of the first lens and the total focal length F meet the condition that f1 / F is larger than or equal to 2.3 and smaller than or equal to 2.9; and the focal length f2 of the second lens and the total focal length F meet the condition that f2 / F is greater than or equal to 2.1 and less than or equal to 2.4.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of projection optical display, and more particularly, to an optical-mechanical lens module and an AR optical display device. BACKGROUND

[0002] With the progress of optical technology, augmented reality (AR) technology has been widely applied in the field of smart wearable devices. The core component of AR technology, the optical-mechanical lens module (i.e., the light engine part), has also undergone significant technical iterations, from DLP light engines, to LCOS light engines, to single green u-LED light engines.

[0003] Full-color u-LED light engines are recognized as the core direction of the next generation of technology development. However, the optical system design of full-color u-LED light engines faces challenges: while maintaining the compactness of the light engine, it is necessary to achieve a breakthrough in the large field of view (FOV).

[0004] Currently, full-color u-LED light engines generally adopt a technical path of combining three RGB monochromatic panels through an X-cube. However, this optical design is limited by existing optical architectures, resulting in a large total optical length of the light engine, and the maximum field of view (FOV) is difficult to break through the bottleneck of 65°. This contradiction between volume and FOV limits the wearing comfort of AR optical display devices and restricts the improvement of user immersion, becoming a key factor restricting the expansion of AR technology to more extensive application scenarios. Therefore, how to optimize the design of the optical-mechanical lens module while ensuring optical performance, and achieve the balance between small volume and large FOV, has become a core problem that needs to be solved in the current development of AR technology. SUMMARY

[0005] The purpose of the present application is to provide a new technical solution for an optical-mechanical lens module and an AR optical display device, aiming to achieve the balance between large FOV, high image quality, and compact structure.

[0006] In a first aspect, embodiments of the present application provide an optical-mechanical lens module, which comprises, in order from the object side to the image side along the optical axis: a first lens, which is a non-spherical positive lens; a second lens, which is a non-spherical positive lens; a third lens, which is a non-spherical negative lens; a fourth lens, which is a non-spherical positive lens; an X-cube color combining prism; and a fifth lens, which is a non-spherical negative lens; The total focal length F of the optical-mechanical lens module is 4.1mm < F < 4.8mm; The focal length f1 of the first lens and the total focal length F satisfy: 2.3 ≤ f1 / F ≤ 2.9; The focal length f2 of the second lens and the total focal length F satisfy: 2.1≤f2 / F≤2.4.

[0007] Optionally, the fifth lens is a field lens, and the object side surface of the fifth lens is a central-concave aspherical surface. and the following air gap constraint is satisfied: The distance A1 between the object side surface center point of the fifth lens and the light exit surface of the X-cube prism is 0.3mm≤A1≤0.35mm. The distance A2 between the object side surface at 0.45 aperture of the fifth lens and the light exit surface of the X-cube prism is 0.28mm≤A2≤0.32mm. The distance A3 between the object side surface at the maximum aperture of the fifth lens and the light exit surface of the X-cube prism is 0.5mm≤A3≤0.6mm.

[0008] Optionally, the sag height of the object side surface of the first lens at the maximum aperture is S1, the sag height of the image side surface of the first lens at the maximum aperture is S2, and the sag height ratio satisfies: 2<S2 / S1<2.3.

[0009] Optionally, the angle between the lens tangent and the optical axis of the image side surface of the first lens at the maximum aperture is A1, the angle between the lens tangent and the optical axis of the object side surface of the first lens at the maximum aperture is A2, and the angle relationship satisfies: 1°<A1-A2<12°, and 0.9<A2 / A1<1.1.

[0010] Optionally, the sag height of the object side surface of the second lens at the maximum aperture is S3, the sag height of the image side surface of the second lens at the maximum aperture is S4, and the sag height ratio satisfies: 2.3<S4 / S3<2.7.

[0011] Optionally, the angle between the lens tangent and the optical axis of the image side surface of the second lens at the maximum aperture is A3, the angle between the lens tangent and the optical axis of the object side surface of the second lens at the maximum aperture is A4, and the angle relationship satisfies: 20°<A3-A4<60°.

[0012] Optionally, the first lens, the second lens, the third lens, the fourth lens and the fifth lens satisfy: 2.6<(T1+T2+T4) / (T3+T5)<3.2; wherein T1, T2, T3, T4 and T5 are the center thicknesses of the first lens, the second lens, the third lens, the fourth lens and the fifth lens, respectively.

[0013] Optionally, the ratio of the center thickness T4 of the fourth lens to the total optical length TTL of the optical mechanical lens module is: 10%≤T4 / TTL≤13%; The refractive index of the fourth lens is 1.8-1.9.

[0014] Optionally, a ratio of the center thickness T3 of the third lens to the total optical length TTL of the optical-mechanical lens module is: 3%≤T3 / TTL≤6%.

[0015] Optionally, a ratio of the total optical length TTL of the optical-mechanical lens module to the maximum aperture D1 of the lens in the optical-mechanical lens module satisfies: 11.3<(TTL / D1)<2.

[0016] Optionally, the optical-mechanical lens module further comprises a light barrier located on the object side of the first lens and a display unit located on the image side of the fifth lens. Effective focal lengths of the lenses in the optical-mechanical lens module are respectively: The focal length of the first lens is f1, and 10.5mm≤f1≤12.5mm. The focal length of the second lens is f2, and 9.06mm≤f2≤11.06mm. The focal length of the third lens is f3, and -5.56mm≤f3≤-3.56mm. The focal length of the fourth lens is f4, and 2.59mm≤f4≤4.59mm. The focal length of the fifth lens is f5, and -8.47mm≤f5≤-6.47mm. The first lens, the second lens, the third lens, and the fifth lens are plastic lenses, and the fourth lens is a glass lens.

[0017] Optionally, the full field of view FOV of the optical-mechanical lens module is 72.8°±0.5° when the working waveband is 460nm-618nm.

[0018] In a second aspect, the embodiments of the present application provide an AR optical display device, which comprises: The optical-mechanical lens module as described in the first aspect; and An optical waveguide device, a diameter of the light barrier of the optical-mechanical lens module matches an entrance pupil diameter of the optical waveguide device.

[0019] The present application has the following beneficial effects: The optical-mechanical lens module provided by the embodiments of the present application realizes effective control of the module volume and consideration of a large field of view (FOV up to 72.8°) under the condition of compact total length (such as only 8.51mm) through unique lens combination design and deep optimization of optical parameters (especially lens focal length). Compared with the traditional optical-mechanical scheme, the present application greatly reduces the thickness of the device while expanding the field of view, thereby improving the comfort and convenience of the user.

[0020] In terms of optical performance, the application quantitatively restricts the focal length ratio of the first lens and the second lens (set the range as 2.3≤f1 / F≤2.9 and 2.1≤f2 / F≤2.4), and adopts the optical power arrangement mode of "positive-positive-negative-positive-negative", so that the optical-mechanical lens module has the characteristics of low optical distortion in the waveband of 460nm-618nm, and the modulation transfer function MTF satisfies MTF>0.55@100lp / mm, effectively correcting aberration, ensuring clear imaging, and greatly improving imaging quality.

[0021] In summary, the optical scheme of the embodiment of the application balances the technical conflicts existing in the volume, field of view and aberration control of the optical-mechanical lens module, and provides optical technical support for the miniaturization and high performance development of the AR optical display device.

[0022] Other features of the present specification and its advantages will become apparent from the following detailed description of exemplary embodiments thereof, which is to be taken in conjunction with the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings incorporated in and forming a part of the specification, illustrate embodiments of the present specification and, together with the description, serve to explain the principles of the present specification.

[0024] Figure 1 A structure and an optical path schematic diagram of an optical-mechanical lens module provided by the application; Figure 2 A partial structure schematic diagram of a first lens in the optical-mechanical lens module provided by the application; Figure 3 A partial structure schematic diagram of a second lens in the optical-mechanical lens module provided by the application; Figure 4 An optical distortion diagram of the optical-mechanical lens module provided by the application; Figure 1 A modulation transfer function diagram of the optical-mechanical lens module provided by the application; Figure 5 Figure 1 A modulation transfer function diagram of the optical-mechanical lens module provided by the application; Figure 6 A structure and an optical path schematic diagram of an optical-mechanical lens module provided by the embodiment 1 of the application; Figure 7 A modulation transfer function diagram of the optical-mechanical lens module provided by the embodiment 1 of the application; Figure 6 A structure and an optical path schematic diagram of an optical-mechanical lens module provided by the embodiment 2 of the application; Figure 8 A modulation transfer function diagram of the optical-mechanical lens module provided by the embodiment 2 of the application; Figure 9 Figure 8 A modulation transfer function diagram of the optical-mechanical lens module provided by the embodiment 2 of the application; Figure 10 ​​A schematic diagram of the structure and optical path of the optical machine lens module provided in Example 3 of the present application; Figure 11 for Figure 10 The modulation transfer function diagram of the optical machine lens module provided; Figure 12 A schematic diagram of the structure and optical path of the optical machine lens module provided in Example 4 of the present application; Figure 13 for Figure 12 The modulation transfer function diagram of the optical machine lens module is provided.

[0025] Description of reference numerals: 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. X-cube color combining prism; 7. Display unit; 8. Aperture. DETAILED DESCRIPTION

[0026] 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.

[0027] 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.

[0028] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0029] 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.

[0030] 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.

[0031] The optical machine lens module and AR optical display device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0032] According to one embodiment of the present application, an optical machine lens module is provided. Figure 1, sequentially includes, from the object side to the image side along the optical axis: a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, an X-cube color combining prism 6 and a fifth lens 5. Wherein, the first lens 1 is a positive aspherical lens. The second lens 2 is a positive aspherical lens. The third lens 3 is a negative aspherical lens. The fourth lens 4 is a positive aspherical lens. The fifth lens 5 is a negative aspherical lens. The total focal length F of the optical mechanical lens module is 4.1mm < F < 4.8mm. The focal length f1 of the first lens 1 and the total focal length F satisfy: 2.3 ≤ f1 / F ≤ 2.9. The focal length f2 of the second lens 2 and the total focal length F satisfy: 2.1 ≤ f2 / F ≤ 2.4.

[0033] The optical mechanical lens module provided by the embodiments of the present application has unique optical design and exhibits excellent performance in the field of projection light machines, and is especially suitable for applications in the field of augmented reality (AR).

[0034] The main components in the optical mechanical lens module provided by the embodiments of the present application are described below.

[0035] The optical mechanical lens module provided by the embodiments of the present application is configured with five lenses, which can be divided into two groups according to their functions and positions: Referring to Figure 1 , the first lens group is located between the diaphragm 8 and the X-cube color combining prism 6, and mainly consists of the first lens 1 (a positive aspherical lens), the second lens 2 (a positive aspherical lens), the third lens 3 (a negative aspherical lens) and the fourth lens 4 (a positive aspherical lens) arranged in sequence along the same optical axis. This lens group is the key to realizing a large field of view FOV (72.8°) and high imaging quality.

[0036] Referring to Figure 1 , the second lens group is arranged between the X-cube color combining prism 6 and the display unit 7, and can only contain the fifth lens 5 (a negative aspherical lens). It is arranged along the same optical axis as the four lenses (the first lens 1 to the fourth lens 4) in the first lens group. In the present application, the fifth lens 5 is a field lens. The fifth lens 5 can appropriately adjust the light propagation path, and can effectively correct the field curvature, which plays an important role in improving the image edge definition and display effect.

[0037] In the design of the optical mechanical projection lens in the present application, referring to Figure 1The first lens 1 is arranged close to the diaphragm 8 (front diaphragm), and is designed as an aspherical positive lens. It undertakes the task of collecting and converging the projection light, and can provide the subsequent optical devices (such as external diffractive optical waveguide devices, etc.) with an incident light beam with extremely high adaptability. Further, the first lens 1 is designed with a large focal length, and the ratio of its focal length f1 to the total focal length F of the entire optical-mechanical lens module satisfies 2.3≤f1 / F≤2.9. This design helps to expand the field of view FOV on the basis of fully guaranteeing the compactness of the optical structure of the optical-mechanical lens module, so that the optical-mechanical lens module can realize an ultra-large range of field of view up to 72.8°. This feature breaks through the field of view limitation of the traditional optical-mechanical scheme, provides optical technical support for creating an immersive visual experience for AR optical display devices, and is one of the core optical elements for ensuring that the optical-mechanical lens module achieves high-performance imaging.

[0038] The second lens 2 is arranged immediately behind the first lens 1 (in the direction from the object side to the image side), and is also designed as an aspherical positive lens. The second lens 2 can not only converge light, but also adjust the propagation path of light. It also has a large focal length, and the ratio of its focal length f2 to the total focal length F of the entire optical-mechanical lens module satisfies 2.1≤f2 / F≤2.4. The large focal length design of the second lens 2 cooperates with that of the first lens 1 to form an optical synergistic effect, and together they form a “positive-positive” focal power combination. This design enhances the convergence ability of light, and with the cooperation of the aspherical surface, effectively controls the spherical aberration, coma and other aberrations, which plays an important role in maintaining image quality while realizing a large field of view.

[0039] The third lens 3 is arranged on the side of the second lens 2 away from the first lens 1, and is designed as an aspherical negative lens. This negative lens can form an optical compensation mechanism with the positive lenses before and after it by controlling the degree of divergence of light, and its negative focal power can balance the excessive convergence trend caused by the positive lenses. It is worth mentioning that, through the optimization design of the aspherical curvature of the third lens 3, the optical distortion can be corrected in the process of diverging light, and the optical distortion rate of the optical-mechanical lens module is controlled within a very small range, i.e., optical distortion < 15%, as shown in Figure 4 .

[0040] In addition, a fourth lens 4 is arranged on the image side of the third lens 3, the fourth lens 4 is a non-spherical positive lens, and is close to the X-cube color combining prism 6. The fourth lens 4 receives the color combining light rays emitted by the X-cube color combining prism 6, and then the color combining light rays pass through the third lens 3, the second lens 2, the first lens 1 in sequence into the diaphragm 8, and finally are projected and imaged by the external diffractive optical waveguide device. Wherein, the third lens 3 and the fourth lens 4 cooperate with each other to form an aberration cancellation mechanism. This design helps the optical mechanical lens module of the present application to realize high image quality output while maintaining a large field of view of 72.8°.

[0041] The first lens 1 to the fourth lens 4 in the optical mechanical projection lens of the present application realize light convergence, field of view expansion, aberration control and high image quality output and other aspects of synergistic effect through their unique optical design and mutual cooperation. The four lenses cooperate with each other, so that the optical mechanical lens module realizes high image quality output of MTF value > 0.55@100lp / mm in the wavelength band of 460nm-618nm while maintaining a large field of view of 72.8°, see Figure 5 . This high image quality output not only reflects in the center area of the image, but also improves the clarity and color restoration of the display edge area, providing high-quality optical performance support for AR optical display devices and meeting the needs of miniaturization and high performance.

[0042] The optical mechanical lens module provided by the embodiment of the present application comprises an X-cube color combining prism 6, which plays an important role in the optical system of projection imaging, and the specific performance is as follows: (1) Precise color combining, constructing complete color information: In order to present rich and varied colors in projection imaging, red (R), green (G) and blue (B) light from the display unit 7 must be combined according to a specific ratio and accurate position. The X-cube color combining prism 6 can fuse three kinds of primary color light, provide mixed light containing complete and accurate color information for the subsequent imaging process, and lay a foundation for the brilliant colors of the projection image.

[0043] (2) Unifying the light path to ensure clear and accurate imaging: In the color combining process, it is crucial to ensure that the three-color light maintains a unified light path direction after merging. If the light path deviates, it will cause projection imaging to appear blurred, color misalignment, and other problems, affecting the final visual effect. The X-cube color combining prism 6 has excellent optical performance, which can accurately control the light path of the three-color light, so that the combined mixed light enters the subsequent lens group (i.e. the first lens 1 to the fourth lens 4) and other optical elements for further processing. This feature ensures the clarity and accuracy of projection imaging, allowing users to enjoy high-quality visual experience.

[0044] (3) Compact adaptation, helping to miniaturize the module design: While pursuing high performance, the small size design of the optical-mechanical lens module is also an important trend in the development of current optical technology. The X-cube color combining prism 6 can well adapt to the overall layout of the optical-mechanical lens module, tightly cooperate with the front group of lenses (such as the first lens group including the first lens 1 to the fourth lens 4) and the rear group of lenses (the second lens group including the fifth lens 5) and other optical elements. In a limited and compact space, the color combining function is completed, neither occupying too much space, nor fully playing its color combining role. This compact and adaptive design helps to achieve the design goal of small size of the optical-mechanical lens module, meeting the needs of modern optical equipment for lightness and smallness.

[0045] In this application, the X-cube color combining prism 6 is used to combine light from different color channels (such as RGB) into a single light path, which is the core component of full-color display. Its precise color combining function ensures accurate color reproduction and mixing, which is crucial to improve display effect.

[0046] In the optical-mechanical projection lens design of this application, referring to Figure 1 , the fifth lens 5 is located between the display unit 7 and the entrance surface of the X-cube color combining prism 6. The fifth lens 5 is an aspherical negative lens, and its negative focal power characteristic enables it to perform divergence processing on the projection light emitted from the display unit 7. Since the light emitted from the display unit 7 may have limitations in angle and distribution during propagation, the fifth lens 5 controls the degree of divergence of the light through aspherical design, so that the light enters the X-cube color combining prism 6 with a more appropriate angle and a more uniform distribution. This process provides good conditions for the subsequent merging of three-color light, ensuring that light of different colors can be accurately converged and mixed in the X-cube color combining prism 6 according to design requirements.

[0047] The aspherical surface design endows the fifth lens 5 with aberration correction capability. In the light-mechanical projection module, aberration is one of the important factors affecting the imaging quality. The fifth lens 5 can correct various aberrations (such as field curvature) that may be generated by the light emitted from the display unit 7, thanks to the aspherical surface design.

[0048] In pursuit of high performance, miniaturization and compact design of the light-mechanical lens module are also design goals of the present application. The reasonable layout and design of the fifth lens 5 help to optimize the spatial structure of the entire optical system. The aspherical shape can reduce the thickness and volume of the lens under the premise of ensuring the optical performance, so that the display unit 7, the fifth lens 5 and the X-cube color combining prism 6 can be arranged more compactly, thereby realizing efficient optical function in a limited space and meeting the design requirements of miniaturization of the light-mechanical lens module.

[0049] The light-mechanical lens module provided by the embodiments of the present application effectively controls the module volume and accommodates a large field of view (FOV up to 72.8°) under the condition of compact total length (e.g., only 8.51 mm). Compared with the traditional light-mechanical scheme, the present application greatly reduces the thickness and heaviness of the device while expanding the field of view FOV, thereby improving the comfort and convenience of user use.

[0050] In terms of optical performance, the present application quantitatively constrains the focal length ratio of the first lens 1 and the second lens 2 (set range: 2.3≤f1 / F≤2.9 and 2.1≤f2 / F≤2.4), and adopts a positive-positive-negative-positive-negative optical power arrangement, so that the light-mechanical lens module has the characteristics of low optical distortion in the 460nm~618nm waveband, and the modulation transfer function MTF satisfies MTF>0.58@100lp / mm, effectively correcting aberration and ensuring clear imaging, greatly improving the imaging quality.

[0051] In summary, the optical scheme of the embodiments of the present application balances the technical conflicts existing in the volume, field of view and aberration control of the light-mechanical lens module, and provides optical technical support for the miniaturization and high performance development of AR optical display devices.

[0052] In some examples of the present application, referring to Figure 1 , the fifth lens 5 is a field lens, the object side surface of which is a central concave aspherical surface; and the following air gap constraints are met: The distance A1 between the center point of the object side surface of the fifth lens 5 and the light emitting surface of the X-cube color combining prism 6 is 0.3mm≤A1≤0.35mm; The distance A2 between the object side surface of the fifth lens 5 at the 0.45 aperture and the light exit surface of the X-cube prism 6 is 0.28mm≤A2≤0.32mm. The distance A3 between the maximum aperture of the object side surface of the fifth lens 5 and the light exit surface of the X-cube prism 6 is 0.5mm≤A3≤0.6mm.

[0053] In the optical-mechanical lens module design of the present application, the X-cube prism 6 undertakes the key optical function, which can combine red, green and blue light beams, providing mixed light containing complete color information for the subsequent imaging process, which is crucial for realizing high-quality color display.

[0054] In the optical-mechanical lens module design of the present application, the fifth lens 5 acts as a field lens, which is arranged between the display unit 7 and the X-cube prism 6. Its main function is to process the projection light emitted from the display unit 7 and about to enter the X-cube prism 6. Field curvature is a common aberration that will cause the consistency of image sharpness at different fields of view to be inconsistent, affecting the imaging quality. The fifth lens 5 can effectively correct aberrations such as field curvature through its special optical properties, so that the processed projection light can be more accurately focused in the subsequent imaging process, thereby significantly improving the imaging quality of the entire optical-mechanical lens module.

[0055] In the example provided in the present application, the air gap between different positions on the object side surface (near the aperture) of the fifth lens 5 and the entrance surface of the X-cube prism 6 is constrained. From the perspective of optical principles, the air gap at different positions will affect the propagation angle and optical path of light on the fifth lens 5. By controlling these air gaps, the object side surface of the fifth lens 5 is actually constrained. Under this constraint condition, the object side surface of the fifth lens 5 will form a special surface similar to a W type, see the fifth lens 5 shown in Figure 1 The surface can further optimize the aberration correction effect, thereby bringing more outstanding imaging performance to the entire optical-mechanical lens module.

[0056] The air gap A1 between the center point of the object side surface of the fifth lens 5 and the light exit surface of the X-cube prism is constrained in the range of 0.3mm≤A1≤0.35mm. By controlling the size of A1, the surface of the central region of the fifth lens 5 can be controlled.

[0057] The air gap A2 between the fifth lens 5 object side 0.45 aperture and the X-cube prism 6 entrance surface is constrained in the range of 0.28mm≤A2≤0.32mm. By setting a suitable A2 value, the intermediate field of view light can be guided to be incident on the lens surface at an optimal angle. On this basis, in combination with the overall surface design of the lens, especially the surface features of the 0.45 aperture region, effective correction of the intermediate field of view aberration can be achieved, ensuring that the intermediate region image has high clarity and accurate color restoration, so that the user can obtain a clear and realistic intermediate field of view picture when viewing.

[0058] The air gap A3 between the fifth lens 5 object side maximum aperture (edge) and the X-cube prism 6 entrance surface is limited to the interval of 0.5mm≤A3≤0.6mm. In optical imaging, the light at the maximum aperture reflects the characteristics of the edge field of view light, and its propagation path and imaging quality have an important influence on the uniformity and integrity of the entire picture.

[0059] Through the parameter constraints in this example of the present application, the quality of the edge image can be significantly improved, so that the entire projection picture can maintain good imaging effect under different fields of view, achieving high uniformity and consistency from the center to the edge of the picture.

[0060] Without correction of field curvature, the edge part of the projection picture will appear blurred due to the inaccurate focusing of light. After the field curvature is corrected by the fifth lens 5 (as a field lens), the light of the edge field of view can be correctly focused on the image plane, greatly improving the clarity of the picture edge, so that the entire projection image can maintain a high level of clarity from the center to the edge, providing users with a clearer and more realistic visual experience.

[0061] Field curvature not only affects the clarity of the image, but also can cause the focusing positions of different color lights to be inconsistent, resulting in color misalignment and deviation. The correction of field curvature by the fifth lens 5 enables the red, green and blue lights to accurately converge on the image plane after being combined by the X-cube prism 6, ensuring the consistency and accuracy of the color of the projection image and avoiding color distortion caused by field curvature.

[0062] For projection systems that pursue large field of view angles, the problem of field curvature is more serious. The presence of the fifth lens 5 enables the light in different regions under large field of view angles to be well corrected, expanding the range of clear imaging of the projection system. Even on a large-size projection screen, users can see clear and distortion-free images at various positions, meeting the application requirements of large scene projection.

[0063] The light emitted by the display unit 7 has certain angle and distribution characteristics, and the fifth lens 5 can pre-process and adjust the light according to the output characteristics of the display unit 7. It can optimize the incident angle and distribution of the light, so that the light enters the subsequent optical system more uniformly, provides a good initial condition for correcting the field curvature, and also helps to improve the light energy utilization of the entire system.

[0064] The fifth lens 5 has corrected the field curvature and adjusted the angle of the light before the light enters the X-cube color combining prism 6. This makes the light entering the X-cube color combining prism 6 more stable and accurate in parameters, which is beneficial to the accurate combination of three-color light. At the same time, the light after correcting the field curvature can better maintain the consistency of the optical path during color combining, reduce the influence of the deviation of the optical path caused by the field curvature on the color combining effect, and further improve the quality of the projection image.

[0065] In the optical-mechanical projection lens module of the present application, the fifth lens 5 cooperates with other lenses to realize comprehensive correction of aberrations of the entire module by reasonably distributing optical power and optimizing optical parameters. The fifth lens 5 is mainly responsible for correcting the field curvature, while other lenses can correct other aberrations, so that the optical-mechanical lens module can achieve high imaging quality in the full field of view.

[0066] In some examples of the present application, referring to Figure 1 , the sag of the object side of the first lens 1 at the maximum aperture is S1, the sag of the object side of the first lens 1 at the maximum aperture is S2, and the sag ratio relationship is satisfied: 2

[0067] Sag is an important optical parameter for describing the shape of a lens surface, which reflects the change in height of the lens surface at the maximum aperture relative to the reference plane.

[0068] In the present application, the first lens 1 is a key optical element in the optical-mechanical lens module close to the diaphragm 8, and the sag ratio relationship of the object side (the surface close to the diaphragm 8, also called the front surface) and the image side (the surface away from the diaphragm 8, also called the rear surface) has a direct impact on the propagation of light and the imaging quality.

[0069] When the light passes through the first lens 1, the surface shape of the first lens 1 determines the refraction path of the light. Based on the different sag ratio of the object side and the image side, the refraction angle and focusing position of the light in the first lens 1 will change. By accurately controlling the ratio of S2 / S1 to be between 2 and 2.3, the propagation process of the light can be optimized, so that the light can be more accurately focused on the subsequent optical element (such as the diaphragm 8).

[0070] The first lens 1 satisfying the sagittal height ratio can make the light rays accurately focus at the stop 8 after being refracted by the first lens 1, reducing the scattering and loss of light rays, and improving the utilization rate of light rays. This helps to improve the imaging brightness of the optical-mechanical lens module, making the projection image clearer and brighter.

[0071] The appropriate sagittal height ratio can effectively correct the aberrations generated by the first lens 1 itself, such as spherical aberration and coma. That is, by controlling the ratio of S2 / S1, the influence of these aberrations on the imaging quality can be reduced, and the clarity and contrast of the image can be improved.

[0072] The light rays emitted by the first lens 1 will be incident on the external diffractive optical device through the stop 8 and finally projected and imaged. This sagittal height ratio ensures that the angle and position of the light rays emitted by the first lens 1 can match the requirements of the stop and the diffractive optical device, so that the light rays can smoothly pass through the subsequent optical system and achieve high-quality projection imaging. If the sagittal height ratio is not appropriate, the light rays may be blocked at the stop or cannot accurately enter the diffractive optical device, affecting the imaging effect.

[0073] In some examples of the present application, referring to Figure 2 , the angle between the lens tangent of the image side of the first lens 1 at the maximum aperture and the optical axis is A1, the angle between the lens tangent of the object side at the maximum aperture and the optical axis is A2, and the angle relationship is 1°<A1-A2<12° and 0.9<A2 / A1<1.1.

[0074] The angle between the lens tangent and the optical axis reflects the inclination of the lens surface at the maximum aperture.

[0075] When the light rays pass through the first lens, the change in the incident angle and the exit angle will affect the propagation of the light rays in the subsequent optical system. By precisely controlling the difference and ratio of A1 and A2, the propagation direction of the light rays can be optimized, so that the light rays can better adapt to the optical characteristics of the subsequent optical elements.

[0076] The angle relationship satisfied by A1 and A2 in this example of the present application, i.e. 1°<A1-A2<12° and 0.9<A2 / A1<1.1, can accurately control the propagation direction of the light rays emitted by the first lens 1 relative to the optical axis. This helps to ensure that the light rays can smoothly pass through the stop 8 and accurately enter the external diffractive optical device. If the angle relationship of A1 and A2 is not appropriate, the light rays may be deflected at the stop 8 or cannot accurately enter the diffractive optical device, resulting in blurred or distorted imaging.

[0077] The suitable angle relationship can also reduce the aberration of the first lens 1 caused by improper light incidence and exit angle. For example, when the angle difference value is too large or the ratio is unreasonable, it may cause larger aberration and affect the image quality. By accurately controlling A1 and A2, the generation of these aberrations can be effectively suppressed, and the clarity and uniformity of imaging can be improved.

[0078] In the present application, for the first lens 1 close to the stop 8 and with positive asphericity, the sagittal height S1 of the object side at the maximum aperture and the sagittal height S2 of the image side at the maximum aperture satisfy 2

[0079] In some examples of the present application, referring to Figure 1 , the sagittal height of the object side of the second lens 2 at the maximum aperture is S3, the sagittal height of the image side at the maximum aperture is S4, and the sagittal height ratio satisfies 2.3

[0080] In the example provided in the present application, for the second lens 2 located on the side of the first lens 1 away from the stop 8, the sagittal height of the object side at the maximum aperture is S3, the sagittal height of the image side at the maximum aperture is S4, and the sagittal height ratio satisfies 2.3

[0081] The second lens 2 is one of the key optical elements in the optical-mechanical lens module, and the sagittal height ratio of the object side and the image side plays an important role in the propagation of light and the imaging quality. The sagittal height reflects the change in height of the lens surface at the maximum aperture relative to the reference plane, and different sagittal height ratios will change the refraction path and focusing of light in the lens. When the light is incident on the second lens 2, proper sagittal height ratio control can make the light refract in the expected way, so as to better match the subsequent optical elements.

[0082] The second lens 2 satisfying the sagittal height ratio relationship in this example of the present application can make the incident light more accurately adjust the propagation direction after passing through the second lens 2, preparing for the subsequent passing through the first lens 1, passing through the diaphragm 8 and entering the external diffractive optical device. This helps to reduce the scattering and loss of light during propagation, improve the utilization rate of light, and enable more light to participate in the final projection imaging, thereby improving the brightness of the imaging.

[0083] The appropriate sagittal height ratio can also effectively correct the aberrations generated by the second lens 2 itself. By controlling the ratio of S4 / S3 to be between 2.3 and 2.7, the influence of these aberrations on the imaging quality can be reduced, and the clarity and uniformity of the image can be improved.

[0084] The light exiting the second lens 2 will pass through the first lens 1, then enter the diaphragm 8, and then be incident to the external diffractive optical device from the diaphragm 8. This sagittal height ratio ensures that the angle and position of the light exiting the second lens 2 can match the requirements of the first lens 1, the diaphragm 8 and the diffractive optical device, so that the light can smoothly pass through the optical system and achieve high-quality projection imaging. If the sagittal height ratio is not appropriate, the light may be abnormal at the first lens 1 or the diaphragm 8, affecting the final imaging effect.

[0085] In some examples of the present application, referring to Figure 3 , the angle between the tangential line of the lens at the maximum aperture of the image side of the second lens 2 and the optical axis is A3, the angle between the tangential line of the lens at the maximum aperture of the object side of the second lens 2 and the optical axis is A4, and the angle relationship is satisfied: 20°<A3-A4<60°.

[0086] The angle between the tangential line of the lens and the optical axis reflects the degree of inclination of the lens surface at the maximum aperture. The angle relationship between the tangential lines of the object side and the image side of the second lens 2 and the optical axis determines the incidence and exit angles of the light on the surface of the second lens 2. When the light passes through the second lens 2, the appropriate angle relationship can make the light propagate according to the ideal path, so as to better connect with the subsequent optical elements.

[0087] Satisfying the angle relationship of 20°<A3-A4<60° can control the propagation direction of the light exiting the second lens 2 relative to the optical axis. This helps to ensure that the light can accurately enter the external diffractive optical device when passing through the first lens 1 and the diaphragm 8. If the angle relationship is not appropriate, the light may be deflected at the first lens 1 or the diaphragm 8, resulting in inaccurate entry into the diffractive optical device and affecting the imaging quality.

[0088] The suitable angle relationship can reduce the aberration of the second lens 2 caused by improper light incidence and emission angles. By precisely controlling the difference between A3 and A4, the generation of these aberrations can be effectively suppressed, and the imaging quality can be improved.

[0089] The second lens 2 can precisely control the light propagation by meeting the design requirements of the ratio of the sag at the maximum aperture of the object side to the sag at the maximum aperture of the image side 2.3 < S4 / S3 < 2.7 and the difference between the tangent angle of the lens at the maximum aperture of the image side and the tangent angle of the lens at the maximum aperture of the object side 20° < A3-A4 < 60°. The suitable sag ratio can optimize the light propagation path, correct aberration, and work cooperatively with the front and rear optical elements; the reasonable angle relationship can precisely control the light propagation direction, reduce the generation of aberration, and enhance the system adaptability. These designs together ensure that the light emitted by the second lens 2 can smoothly enter the diffractive optical device through the first lens 1 and the diaphragm 8, and finally realize high-quality projection imaging, thereby improving the performance and stability of the optical-mechanical lens module.

[0090] In some examples of the present application, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5 meet the relationship 2.6 < (T1+T2+T4) / (T3+T5) < 3.2, where T1, T2, T3, T4, and T5 are the center thicknesses of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5, respectively.

[0091] In the optical-mechanical lens module design of the present application, specific requirements are proposed for the center thicknesses of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5, i.e., meeting the relationship 2.6 < (T1+T2+T4) / (T3+T5) < 3.2, where the first lens 1, the second lens 2, and the fourth lens 4 are positive lenses, and the third lens 3 and the fifth lens 5 are negative lenses.

[0092] From the perspective of overall optical design of the optical-mechanical lens module, the center thickness of the lens is one of the key optical parameters that affect light propagation and imaging quality. Different lenses have different optical functions, and reasonable allocation of the center thickness is crucial for optimizing the performance of the entire optical-mechanical lens module. This relationship ensures the balance of the optical structure and the coordination of the optical performance of the optical-mechanical lens module by limiting the combination and proportion of the center thicknesses of the lenses.

[0093] A reasonable lens thickness ratio helps to effectively correct various aberrations in the optical-mechanical lens module. In the optical-mechanical lens module, the existence of aberrations will affect the imaging quality, such as spherical aberration, coma, astigmatism, and field curvature, etc. Different thickness of lenses has different correction ability for aberrations. By controlling the ratio of (T1+T2+T4) / (T3+T5) between 2.6 and 3.2, the positive and negative lenses can play a synergistic role in correcting aberrations, thereby significantly improving the clarity and contrast of imaging, and making the projected image more realistic and accurate.

[0094] The thickness ratio relationship helps to maintain the compactness and stability of the optical-mechanical lens module under the premise of meeting the optical performance requirements. In addition, by controlling the ratio of the center thickness of each lens, more uniform distribution of light on the entire image plane can be achieved, thereby improving the uniformity of imaging quality. In the optical-mechanical lens module, the imaging quality of different areas of the image plane may be different due to the difference in light propagation. A reasonable lens thickness ratio can adjust the focusing of light at different positions on the image plane, reduce the difference in imaging quality between the edge and center areas of the image plane, and make the entire projected image have consistent clarity and color restoration, providing users with a better visual experience.

[0095] In some examples of the present application, the ratio of the center thickness T4 of the fourth lens 4 to the total optical length TTL of the optical-mechanical lens module is: 10%≤T4 / TTL≤13%. The refractive index of the fourth lens 4 is 1.8~1.9.

[0096] In the design of the optical-mechanical lens module of the present application, two key parameter requirements are proposed for the fourth lens 4. On the one hand, the ratio of the center thickness T4 to the total optical length TTL of the optical-mechanical lens module satisfies 10%≤T4 / TTL≤13%; on the other hand, the refractive index of the fourth lens 4 is in the range of 1.8~1.9.

[0097] The center thickness T4 of the fourth lens 4 accounts for 10%~13% of the total optical length TTL, which makes the fourth lens 4 have a proper power distribution in the optical-mechanical lens module. When the light exits from the X-cube color combiner prism 6 and enters the fourth lens 4, a suitable center thickness T4 can ensure that the light is accurately focused when passing through the fourth lens 4. If T4 / TTL is too small, the fourth lens 4 may not provide enough power, resulting in insufficient focusing of light and affecting the clarity of imaging; if T4 / TTL is too large, it may introduce too much aberration, such as spherical aberration and chromatic aberration, etc. By controlling it within the range of 10%~13%, the fourth lens 4 can focus light while effectively cooperating with other lenses to correct aberrations and improve imaging quality.

[0098] The refractive index of the fourth lens 4 is between 1.8 and 1.9, which helps to further optimize the aberration correction effect. Different refractive index materials have different refractive abilities for light, and within this refractive index range, the fourth lens 4 can better cooperate with other lenses to correct chromatic aberration and monochromatic aberration in the optical and mechanical lens module. For example, in terms of correcting chromatic aberration, a suitable refractive index can make light of different wavelengths have a closer refraction angle when passing through the fourth lens 4, reducing the dispersion phenomenon, thereby improving the color restoration and clarity of the image.

[0099] After the fourth lens 4 receives the light emitted by the X-cube color combiner 6, the light is transmitted to the diaphragm 8 in turn through the third lens 3, the second lens 2, and the first lens 1. A suitable T4 / TTL ratio and refractive index range allows the angle and position of the light emitted by the fourth lens to match the requirements of the subsequent lenses. If the parameters of the fourth lens 4 are not suitable, it may cause the angle deviation of the emitted light to be too large, so that the subsequent lenses cannot effectively receive and adjust the light, affecting the light transmission efficiency of the entire optical and mechanical lens module. By controlling these two parameters in this example, it can ensure that the light is smoothly transmitted between lenses, improving the stability and reliability of the module.

[0100] A suitable thickness ratio and refractive index range of the fourth lens 4 helps to enhance the resistance of the optical and mechanical lens module to environmental changes. For example, when the temperature changes, the lenses made of different materials may expand or contract due to heat, and suitable parameters can reduce lens deformation and optical performance degradation caused by thermal stress, ensuring that the system can maintain stable imaging quality in different environments.

[0101] In some examples of the present application, the ratio of the central thickness T3 of the third lens 3 to the total optical length TTL of the optical and mechanical lens module is: 3%≤T3 / TTL≤6%.

[0102] In the optical and mechanical lens module design of the present application, it is pointed out that the ratio of the central thickness T3 of the third lens 3 to the total optical length TTL of the optical and mechanical lens module satisfies 3%≤T3 / TTL≤6%. The third lens 3 is in a specific position in the optical and mechanical lens module, which receives light adjusted by the fourth lens 4 (positive focal length aspherical lens), and then the light is transmitted to the diaphragm 8 through the second lens 2 and the first lens 1. The central thickness T3 ratio has an important influence on the performance of the optical and mechanical lens module.

[0103] When 3%≤T3 / TTL≤6%, the third lens 3 has a suitable central thickness T3. This enables it to accurately focus the light rays from the fourth lens 4 in the optical-mechanical lens module. If T3 / TTL is too small, i.e., the central thickness of the third lens 3 is too thin, its focal power may be insufficient to focus the light rays to the ideal position, resulting in scattering or inaccurate focusing of the light rays during subsequent transmission, affecting the clarity of the image. If T3 / TTL is too large, the third lens 3 is too thick, which may introduce excessive aberration, interfering with the normal focusing of light rays, also reducing the imaging quality. For example, during the imaging process, a suitable central thickness T3 of the third lens 3 can ensure that the light rays enter the second lens 2 at a more accurate angle and position after passing through it, laying a good foundation for subsequent imaging steps.

[0104] The third lens 3 cooperates with the fourth lens 4, which adjusts the combined light rays emitted by the X-cube color combiner 6. The third lens 3 adjusts the direction of the light rays according to the overall requirements of the optical-mechanical lens module, allowing the light rays to be transmitted more smoothly to other optical elements, reducing energy loss and directional deviation of the light rays during propagation, and improving light utilization.

[0105] The central thickness T3 of the third lens 3 plays a key role in correcting aberration in the optical-mechanical lens module. Within this proportion range, the third lens 3 can work together with other lenses to effectively correct aberration.

[0106] By controlling T3 / TTL within the range of 3%~6%, the third lens 3 helps to improve the uniformity of imaging quality on the image plane. In the optical-mechanical lens module of the present application, the imaging quality of different areas of the image plane may differ due to the influence of light propagation and aberration. A suitable central thickness T3 of the third lens 3 can adjust the focusing of light rays at different positions on the image plane, reduce the difference in imaging quality between the edge and center areas of the image plane, and make the entire projection image have consistent clarity and color restoration, providing users with a better visual experience.

[0107] In addition, the T3 / TTL ratio of 3%~6% helps to achieve compactness design of the optical structure of the optical-mechanical lens module. In AR optical display devices, a compact optical-mechanical lens module can reduce the volume and weight of the device. The third lens 3, under the premise of meeting the optical performance requirements, through a suitable thickness ratio, does not occupy too much space, so that the optical-mechanical lens module can realize efficient optical function in a limited space, meeting the needs of AR optical display devices for miniaturization and light weight.

[0108] The reasonable center thickness proportion of the third lens 3 and the fourth lens 4 cooperates with each other, and the propagation path of the light in the whole optical-mechanical lens module is optimized. The center thickness T4 of the fourth lens 4 refracts and focuses the light, and lays a foundation for the subsequent propagation of the light. The third lens 3 adjusts the light more finely according to the overall requirements of the optical-mechanical lens module, so that the light passes through other optical elements at a more suitable angle and direction. This synergistic effect reduces the scattering and loss of the light in the propagation process, improves the utilization rate of the light, and thus improves the brightness of the imaging.

[0109] The constraint on the center thickness proportion of the third lens 3 and the fourth lens 4 helps to realize the compactness design of the optical structure of the optical-mechanical lens module. In the AR optical display device, the compact optical-mechanical lens module can reduce the volume and weight of the device and improve the portability. The fourth lens 4 and the third lens 3 do not occupy too much space by suitable center thickness proportions under the premise of meeting their respective optical performance requirements. They are reasonably arranged with other lenses, so that the whole optical-mechanical lens module can realize efficient optical function in a limited space, meeting the needs of miniaturization and light weight of the AR optical display device.

[0110] In some examples of the present application, the ratio of the total optical length TTL of the optical-mechanical lens module to the maximum aperture D1 of the lens in the optical-mechanical lens module satisfies: 11.3 < (TTL / D1) < 2.

[0111] In the present application, referring to Figure 1 , the fifth lens 5 is the lens with the largest aperture in the whole optical-mechanical lens module, that is, the aperture of the fifth lens 5 is D1.

[0112] When the ratio of TTL / D1 is between 1.3 and 2, the total optical length TTL of the optical-mechanical lens module can be effectively controlled. A smaller ratio means that the total optical length will not be too long under the condition of a given maximum lens aperture D1. For example, if D1 is fixed, when the ratio is close to 1.3, TTL is relatively short, which helps to realize the compactness design of the lens module. In the AR optical display device, the compact optical-mechanical lens module can reduce the volume and weight of the device, meeting the needs of users for light and small products.

[0113] The ratio range in this example of the present application controls the total optical length while also taking into account the optical performance. If the ratio is too small in order to pursue extreme compactness, it can lead to the design of the lens being too limited and unable to meet the requirements of the optical system in terms of light focusing, aberration correction, etc. The ratio range of 1.3-2 can reasonably control the total optical length on the premise of ensuring the optical performance, and achieve a balance between performance and size. For example, in some high-end AR optical display devices, both high-quality imaging performance and small device size are required, and this ratio range can well meet this demand.

[0114] The ratio range of TTL / D1 plays an important role in the optical-mechanical lens module of the present application to achieve a large field of view of 72.8°. A larger field of view requires the optical-mechanical lens module to be able to receive and process a wider range of light. When the ratio is between 1.3 and 2, the optical-mechanical lens module has enough space and structure to design appropriate lens combinations to achieve coverage of a large field of view. For example, the fifth lens 5, as a lens with a specific aperture D1, in cooperation with other lenses, can enable light to enter the lens and be accurately imaged within a larger angular range under a reasonable TTL. If the TTL is too long or too short, it can affect the propagation and focusing of light within a large field of view, resulting in problems such as increased aberration and blurred imaging at the edge of the field of view.

[0115] In some examples of the present application, the optical-mechanical lens module further comprises a diaphragm 8 located on the object side of the first lens 1 and a display unit 7 located on the image side of the fifth lens 5. The effective focal lengths of the lenses in the optical-mechanical lens module are respectively: The focal length of the first lens 1 is f1, and 10.5mm≤f1≤12.5mm; The focal length of the second lens 2 is f2, and 9.06mm≤f2≤11.06mm; The focal length of the third lens 3 is f3, and -5.56mm≤f3≤-3.56mm; The focal length of the fourth lens 4 is f4, and 2.59mm≤f4≤4.59mm; The focal length of the fifth lens 5 is f5, and -8.47mm≤f5≤-6.47mm; The first lens 1, the second lens 2, the third lens 3, and the fifth lens 5 are plastic lenses, and the fourth lens 4 is a glass lens.

[0116] The diaphragm 8 is designed as a front diaphragm and is located on the object side of the first lens 1, i.e. on the optical path between the first lens 1 and the coupling-in area of the external diffractive optical waveguide device (not shown in the figure).

[0117] The front aperture stop, as a key optical control component, mainly functions to control the light flux entering the subsequent optical elements (such as the diffractive optical waveguide device mentioned in the above paragraph). By limiting the aperture size of the light beam, the aperture stop 8 helps to effectively reduce the interference of stray light and non-imaging light, ensuring that only the light within a specific aperture range can smoothly pass through and enter the subsequent optical elements (such as the diffractive optical waveguide device) for processing. This design can significantly improve the clarity and contrast of the image, avoiding the influence of stray light on the imaging quality.

[0118] From the display unit 7, it can be composed of chips that can emit different colors of light, for example, the R display chip is responsible for emitting red light, the G display chip is responsible for emitting green light, and the B display chip is responsible for emitting blue light. These three colors are the basis for forming image colors, and through different intensities and proportions, a wide variety of colors can be presented. The red, green, and blue three-color light processed by the fifth lens 5 can complete color mixing in the X-cube color combining prism 6, providing mixed light containing complete color information for subsequent projection imaging.

[0119] In the optical-mechanical lens module provided in the present application, the first lens 1 and the second lens 2 are positive focal length lenses with focal lengths that enable them to converge the light entering the optical-mechanical lens module. The focal lengths of these two lenses are relatively large, and they are designed in combination with the focal length ranges of the third lens 3, the fourth lens 4, and the fifth lens 5 to ensure that the light within the entire large field of view FOV range (72.8°) can form a clear image on the image plane, achieving high-quality imaging under a large field of view.

[0120] The combination of lenses with different materials and focal length ranges can collectively correct various aberrations in the optical-mechanical lens module. The four plastic lenses (first lens 1, second lens 2, third lens 3, and fifth lens 5) and one glass lens (fourth lens 4) have different optical properties, and they work together to correct multiple aberrations, making the image on the image plane clearer and more accurate, and improving the imaging quality.

[0121] In the case of a large field of view, the imaging quality of different areas on the image plane may differ due to the influence of light propagation and aberrations. By reasonably setting the focal lengths of each lens, the light is evenly distributed on the entire image plane, reducing the difference in imaging quality between the edge and center regions of the image plane. For example, the fourth lens 4 and the fifth lens 5, according to their focal length ranges, accurately focus and adjust the light in the edge field of view, avoiding problems such as edge blurring or distortion, thereby making the entire projection image have consistent clarity and color reproduction.

[0122] The application adopts the combination of plastic lenses and glass lenses, which considers the cost factor and optimizes the system performance. The plastic lenses have the advantages of low cost and easy processing, and are suitable for manufacturing the first lens 1, the second lens 2, the third lens 3 and the fifth lens 5. They can be made into aspheric lenses according to the requirements of optical design to achieve better aberration correction effect. The glass lenses have excellent optical properties such as high refractive index and dispersion coefficient, and the fourth lens 4 adopts glass material, which can further improve the imaging quality and stability of the optical-mechanical lens module.

[0123] The focal length range of each lens is set to achieve optical performance while considering the compactness and manufacturing cost of the optical structure of the optical-mechanical lens module. The reasonable focal length range enables the spacing between lenses and the overall optical length to be controlled within a suitable range, which is beneficial to the compact design of the optical-mechanical lens module. At the same time, the suitable focal length range also reduces the difficulty and cost of lens manufacturing. For example, the focal length range of each lens avoids excessively large focal length leading to excessively large system volume, and also avoids excessively small focal length increasing the complexity of manufacturing process.

[0124] In a more preferred example, the optical structure of the optical-mechanical lens module is shown in Figure 1 The effective focal lengths of the first lens 1 to the fifth lens 5 in the optical-mechanical lens module are respectively: The focal length f1 of the first lens 1 is 11.5 mm; The focal length f2 of the second lens 2 is 11.06 mm; The focal length f3 of the third lens 3 is -4.56 mm; The focal length f4 of the fourth lens 4 is 3.59 mm; The focal length f5 of the fifth lens 5 is -7.47 mm; The first lens 1, the second lens 2, the third lens 3 and the fifth lens 5 are plastic lenses, and the fourth lens 4 is a glass lens; On this basis, the optical parameters of the optical-mechanical lens module are as follows: Table 1

[0125] Table 2

[0126] In the above example, the main parameters of the optical-mechanical lens module design include: total focal length F is 4.425 mm; FOV is 72.8°; entrance pupil diameter is 1.9 mm, entrance pupil distance is 0.2 mm; image element size is 5 μm; image plane size is 5 mm~6 mm; optical distortion is <15%, as shown in Figure 4; the working waveband is 460nm-618nm, and the high image quality output of MTF value >0.55@100lp / mm in the waveband of 460nm-618nm is achieved, see Figure 5 .

[0127] In some examples of the present application, the optical mechanical lens module has a full field of view FOV of 72.8°±0.5° when the working waveband is 460nm-618nm.

[0128] In the optical mechanical lens module provided by the present application, when the optical mechanical lens module is in the working waveband of 460nm-618nm, the full field of view FOV can reach 72.8°, allowing a slight deviation of ±0.5°. This means that the optical mechanical lens module can achieve a larger field of view range of 72.3°-73.3° when processing light in this waveband.

[0129] The optical mechanical lens module of the present application is further illustrated by Examples 1-4 below.

[0130] Example 1 Referring to Figure 6 , the optical mechanical lens module provided by Example 1 includes the following optical elements in order from the object side to the image side along the optical axis: The diaphragm 8 is a front diaphragm; The first lens 1 is a plastic aspherical positive lens; The second lens 2 is a plastic aspherical positive lens; The third lens 3 is a plastic aspherical negative lens; The fourth lens 4 is a glass aspherical positive lens; The X-cube color combining prism 6 is made of glass; The fifth lens 5 is a plastic aspherical negative lens; and The display unit 7 can emit R, G, and B light.

[0131] The optical parameters of the optical mechanical lens module shown in Example 1 are shown in Table 3 and Table 4 below, wherein Table 4 is the aspherical design of each aspherical lens in Table 3.

[0132] Table 3

[0133] Table 4

[0134] For the optical mechanical lens module provided by Example 1, referring to Figure 7 , Figure 7 is the modulation transfer function diagram of the optical mechanical lens module provided by Example 1, from Figure 7It can be seen that MTF > 0.48@100lp / mm.

[0135] Embodiment 2 Referring to Figure 8 The optical-mechanical lens module provided in this embodiment 2 comprises, in sequence from the object side to the image side along the optical axis, the following optical elements: The diaphragm 8 is a front diaphragm; The first lens 1 is a plastic aspherical positive lens; The second lens 2 is a plastic aspherical positive lens; The third lens 3 is a plastic aspherical negative lens; The fourth lens 4 is a glass aspherical positive lens; The X-cube color combiner 6 is made of glass; The fifth lens 5 is a plastic aspherical negative lens; and The display unit 7 is capable of emitting R, G and B light rays.

[0136] The specific optical parameters of the optical-mechanical lens module shown in this embodiment 2 are shown in Table 5 and Table 6, wherein Table 6 is the aspherical design of each aspherical lens in Table 5.

[0137] Table 5

[0138] Table 6

[0139] For the optical-mechanical lens module provided in this embodiment 2, referring to Figure 9 , Figure 9 The modulation transfer function diagram of the optical-mechanical lens module provided in this embodiment 2 is shown in Figure 9 It can be seen that MTF > 0.48@100lp / mm.

[0140] Embodiment 3 Referring to Figure 10 The optical-mechanical lens module provided in this embodiment 3 comprises, in sequence from the object side to the image side along the optical axis, the following optical elements: The diaphragm 8 is a front diaphragm; The first lens 1 is a plastic aspherical positive lens; The second lens 2 is a plastic aspherical positive lens; The third lens 3 is a plastic aspherical negative lens; The fourth lens 4 is a glass aspherical positive lens; The X-cube color combiner 6 is made of glass; The fifth lens 5 is a plastic aspherical negative lens; and The display unit 7 is capable of emitting R, G and B light rays.

[0141] The specific optical parameters of the optical-mechanical lens module shown in Embodiment 3 are shown in Table 7 and Table 8, wherein Table 8 is the aspherical surface design of each aspherical lens in Table 7.

[0142] Table 7

[0143] Table 8

[0144] For the optical-mechanical lens module provided in Embodiment 3, refer to Figure 11 , Figure 11 The modulation transfer function diagram of the optical-mechanical lens module provided in Embodiment 3 is shown in Figure 11 It can be known that MTF > 0.48@100lp / mm.

[0145] Embodiment 4 Refer to Figure 12 The optical-mechanical lens module provided in Embodiment 4 comprises the following optical elements in order from the object side to the image side along the optical axis: The diaphragm 8 is a front diaphragm; The first lens 1 is a plastic aspherical positive lens; The second lens 2 is a plastic aspherical positive lens; The third lens 3 is a plastic aspherical negative lens; The fourth lens 4 is a glass aspherical positive lens; The X-cube color combiner 6 is made of glass; The fifth lens 5 is a plastic aspherical negative lens; and The display unit 7 can emit R, G and B light.

[0146] The specific optical parameters of the optical-mechanical lens module shown in Embodiment 4 are shown in Table 9 and Table 10, wherein Table 10 is the aspherical surface design of each aspherical lens in Table 9.

[0147] Table 9

[0148] Table 10

[0149] For the optical-mechanical lens module provided in Embodiment 4, refer to Figure 13 , Figure 13 The modulation transfer function diagram of the optical-mechanical lens module provided in Embodiment 4 is shown in Figure 13 It can be known that MTF > 0.48@100lp / mm.

[0150] According to the optical-mechanical lens module provided in the above-mentioned embodiments 1 to 4, the optical distortion is less than 15%.

[0151] According to another embodiment of the present application, an AR optical display device is provided, comprising the optical-mechanical lens module and the optical waveguide device as described above; wherein the diameter of the stop 8 of the optical-mechanical lens module matches the entrance pupil diameter of the optical waveguide device.

[0152] The specific implementation of the AR optical display device of the embodiments of the present application can refer to the above-mentioned embodiments of the optical-mechanical lens module, and thus at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here.

[0153] In the above embodiments, the focus is on the differences between the embodiments, and the different optimization features between the embodiments can be combined to form a better embodiment as long as they are not contradictory. Considering the brevity of the writing, it will not be repeated here.

[0154] Although some specific embodiments of the present application have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration, not for limiting the scope of the present application. Those skilled in the art should understand that the above embodiments can 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. An optical machine lens module, characterized in that: Along the optical axis from the object side to the image side, it includes: The first lens (1) is an aspheric positive lens; The second lens (2) is an aspherical positive lens; The third lens (3) is an aspherical negative lens; The fourth lens (4) is an aspherical positive lens; X-cube color combining prism (6); and, The fifth lens (5) is an aspherical negative lens; The total focal length F of the optical machine lens module is 4.1mm<F<4.8mm; The focal length f1 of the first lens (1) and the total focal length F satisfy: 2.3≤f1 / F≤2.9; The focal length f2 of the second lens (2) and the total focal length F satisfy: 2.1≤f2 / F≤2.

4.

2. The optical machine lens module according to claim 1, wherein: The fifth lens (5) is a field lens, and its object side is an aspheric surface with a central depression; And the following air spacing constraints are met: The distance A1 between the center point of the object side surface of the fifth lens (5) and the light-emitting surface of the X-cube color-combining prism (6) is 0.3 mm ≤ A1 ≤ 0.35 mm; The distance A2 between the object side surface of the fifth lens (5) at 0.45 aperture and the light-emitting surface of the X-cube color combining prism (6) is 0.28mm≤A2≤0.32mm; The distance A3 between the maximum aperture of the object side of the fifth lens (5) and the light-emitting surface of the X-cube color-combining prism (6) is 0.5 mm ≤ A3 ≤ 0.6 mm.

3. The optical machine lens module according to claim 1, wherein: The sag height of the object side surface of the first lens (1) at the maximum aperture is S1, and the sag height of the object side surface at the maximum aperture is S2, and the sag height ratio relationship is satisfied: 2<S2 / S1<2.

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4. The optical machine lens module according to claim 1 or 3, wherein: The angle between the tangent line of the image side of the first lens (1) at the maximum aperture and the optical axis is A1, and the angle between the tangent line of the object side of the first lens (1) at the maximum aperture and the optical axis is A2, and the angle relationship is satisfied: 1°<A1-A2<12°, and 0.9<A2 / A1<1.

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5. The optical machine lens module according to claim 1, wherein: The object side surface of the second lens (2) has a sag height of S3 at the maximum aperture, and the image side surface has a sag height of S4 at the maximum aperture, and the sag height ratio relationship is satisfied: 2.3<S4 / S3<2.

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6. The optical machine lens module according to claim 1 or 5, characterized in that: The angle between the lens tangent line of the image side surface of the second lens (2) at the maximum aperture and the optical axis is A3, and the angle between the lens tangent line of the object side surface of the second lens (2) at the maximum aperture and the optical axis is A4, and the angle relationship is satisfied: 20°<A3-A4<60°.

7. The optical machine lens module according to claim 1, wherein: The first lens (1), the second lens (2), the third lens (3), the fourth lens (4) and the fifth lens (5) satisfy the following conditions: 2.6<(T1+T2+T4) / (T3+T5)<3.2; wherein T1, T2, T3, T4 and T5 are the center thicknesses of the first lens (1), the second lens (2), the third lens (3), the fourth lens (4) and the fifth lens (5), respectively.

8. The optical machine lens module according to claim 1 or 7, wherein: The ratio of the center thickness T4 of the fourth lens (4) to the total optical length TTL of the optical machine lens module is: 10%≤T4 / TTL≤13%; The refractive index of the fourth lens (4) is 1.8-1.

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9. The optical machine lens module according to claim 1 or 7, wherein: The ratio of the center thickness T3 of the third lens (3) to the total optical length TTL of the optical machine lens module is: 3%≤T3 / TTL≤6%.

10. The optical machine lens module according to claim 1, wherein: The ratio of the total optical length TTL of the optical machine lens module to the maximum aperture D1 of the lens in the optical machine lens module satisfies: 11.3<(TTL / D1)<2.

11. The optical machine lens module according to claim 1, wherein: The optical machine lens module further includes a stop (8) located on the object side of the first lens (1), and a display unit (7) located on the image side of the fifth lens (5); The effective focal lengths of the lenses in the optical machine lens module are: The focal length of the first lens (1) is f1, 10.5 mm ≤ f1 ≤ 12.5 mm; The focal length of the second lens (2) is f2, 9.06 mm ≤ f2 ≤ 11.06 mm; The focal length of the third lens (3) is f3, -5.56mm≤f3≤-3.56mm; The focal length of the fourth lens (4) is f4, 2.59mm≤f4≤4.59mm; The focal length of the fifth lens (5) is f5, -8.47mm≤f5≤-6.47mm; The first lens (1), the second lens (2), the third lens (3) and the fifth lens (5) are plastic lenses, and the fourth lens (4) is a glass lens.

12. The optical machine lens module according to claim 1, wherein: When the optical machine lens module operates in a wavelength band of 460 nm to 618 nm, the full field of view (FOV) is 72.8°±0.5°.

13. An AR optical display device, characterized in that: include: The optical machine lens module according to any one of claims 1 to 12; and The optical waveguide device has an aperture diameter that matches the entrance pupil diameter of the optical waveguide device.

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