Optical machine lens module and near-eye optical display equipment

Abstract

The embodiment of the invention provides an optical machine lens module and near-eye optical display equipment. Wherein the ray machine lens module sequentially comprises a first lens group and a second lens group from an object side to an image side along an optical axis; the first lens group comprises a first lens with positive focal power, and the first lens is a glass lens; the second lens group comprises three plastic lenses; the three plastic lenses are a second lens with positive focal power, a third lens with negative focal power and a fourth lens with negative focal power in sequence along the optical axis; wherein the first lens is a common lens for keeping structural parameters fixed when the first lens is adaptive to MicroLED micro display screens with different resolutions; the total optical length TTL of the ray machine lens module is larger than or equal to 5.1 mm and smaller than or equal to 5.6 mm.

Description

Technical Field

[0001] This application relates to the field of optical imaging technology, specifically to a miniature optical engine for near-eye display devices such as augmented reality (AR), and more particularly to an optical engine lens module and a near-eye optical display device. Background Technology

[0002] MicroLEDs (micro-light-emitting diodes) are considered an ideal micro-display solution for the optical mechanisms of next-generation near-eye displays (such as AR glasses) due to their advantages such as high brightness, high contrast, small size, and long lifespan. However, the physical size of MicroLED micro-displays is typically extremely small (e.g., a diagonal dimension of less than 0.5 inches), which presents multiple challenges to the design of their accompanying optical engine lenses. First, to meet the requirement of ultra-thin and lightweight AR devices, the optical engine lens must have a short overall optical length and a light weight. However, under such a compact size constraint, traditional optical designs struggle to achieve a large field of view (FOV) simultaneously, thus limiting the immersive experience.

[0003] Secondly, MicroLED optical engines need to operate stably under various ambient temperatures, which requires the optical engine lens to maintain good image quality stability over a wide temperature range (e.g., 10℃ to 50℃). Although conventional all-plastic optical engine lenses are beneficial for weight reduction, their optical parameters are significantly affected by temperature, resulting in prominent issues such as image plane drift and image quality degradation, making it difficult to meet the stringent environmental adaptability requirements.

[0004] Furthermore, to balance image quality and compact size, multi-element lens combinations are often required to correct aberrations. If all lenses are made of glass, the lens weight and cost will be prohibitively high; if a complex optical architecture (such as a freeform prism) is used, challenges arise in manufacturing, assembly yield, and cost control. This makes it difficult for traditional solutions to achieve a balance between a wide field of view and high image quality under the rigid constraints of short overall optical length and light weight.

[0005] Furthermore, with the iteration of display technology, the resolution of MicroLED microdisplays continues to improve. Existing optical engine lens designs are usually customized for specific resolution displays, lacking flexibility. Developing entirely new lenses for displays of different resolutions would significantly increase the research and development cycle and costs.

[0006] Therefore, there is a lack of optical lens solutions in the present technology that can achieve a large field of view, high image quality, excellent wide temperature stability, and flexibility to adapt to different resolution displays within a short optical length. Summary of the Invention

[0007] The purpose of this application is to provide a new technical solution for an optical engine lens module and a near-eye optical display device, so as to solve at least one of the technical problems existing in the prior art, namely, the difficulty in balancing short optical length and large field of view, insufficient temperature stability, and difficulty in adapting to displays with different resolutions.

[0008] In a first aspect, this application provides an optical-mechanical lens module, which comprises, along the optical axis from the object side to the image side, the following components in sequence: The first lens group includes a first lens with positive optical power, and the first lens is a glass lens; The second lens group includes three plastic lenses, which are arranged sequentially along the optical axis as a second lens with positive optical power, a third lens with negative optical power, and a fourth lens with negative optical power. The first lens is a common lens that maintains fixed structural parameters when adapting to MicroLED microdisplays of different resolutions; The total optical length (TTL) of the optical engine lens module is 5.1mm ≤ TTL ≤ 5.6mm.

[0009] Optionally, the refractive index Nd1 of the first lens is 1.58≤Nd1≤1.6; The refractive index Nd2 of the second lens is 1.6 ≤ Nd2 ≤ 1.7; The refractive indices Nd3 and Nd4 of the third lens and the fourth lens satisfy the following conditions: 1.65≤Nd3 and Nd4≤1.68, and Nd2 is less than Nd3 and Nd4.

[0010] Optionally, the center thickness of the second lens is T2, the center thickness of the third lens is T3, and the center thickness of the fourth lens is T4, and satisfies: 0.8 < (T2 + T3) / T4 < 1.0.

[0011] Optionally, the center thickness T1 of the first lens satisfies 14.6% ≤ T1 / TTL ≤ 15.8%; The center thicknesses T2, T3, and T4 of the second lens, the third lens, and the fourth lens respectively satisfy the following conditions: 12.05%≤T2 / TTL≤14.8%, 5.5%≤T3 / TTL≤6.6%, and 22.94%≤T4 / TTL≤30.6%.

[0012] Optionally, the maximum aperture of all lenses in the optical-mechanical lens module is D0, and satisfies: 0.2 < D0 / TTL < 1.0.

[0013] Optionally, the first lens, the second lens, the third lens, and the fourth lens are all aspherical lenses with a conic coefficient of -20 to 20.

[0014] Optionally, the optical engine lens module satisfies the following conditions: The air gap between any two adjacent lenses shall not be less than 0.080 mm; The center thickness of any lens shall not be less than 0.305 mm; The distance between the image-side surface and the image-side surface of the fourth lens is not less than 0.5 mm.

[0015] Optionally, the effective focal length f1 of the first lens ranges from 1 mm to 5 mm; The effective focal length f2 of the second lens ranges from 1mm to 5mm; The effective focal length f3 of the third lens is in the range of -5mm to -1mm; The effective focal length f4 of the fourth lens is in the range of -150mm to -100mm, -20mm to -10mm, or -10mm to -1mm.

[0016] Optionally, the effective focal length f of the optical-mechanical lens module is 4.3mm~5.0mm, and the field of view (FOV) of the optical-mechanical lens module is not less than 35° when the working wavelength is 502nm~552nm.

[0017] Optionally, the optical-mechanical lens module further includes a MicroLED microdisplay disposed at the image plane position, wherein the distance from the image side of the fourth lens near the MicroLED microdisplay to the light-emitting surface of the MicroLED microdisplay is not less than 0.5 mm; The MicroLED microdisplay has a pixel size of 2.5μm and resolutions including 660×880, 720×960, or 780×1040.

[0018] Secondly, this application provides a near-eye optical display device, the near-eye optical display device comprising: The optical-mechanical lens module as described in the first aspect; and... The light guide device is provided in which the exit pupil diameter of the optical engine lens module is matched with the entrance pupil diameter of the light guide device.

[0019] One technical advantage of this application is: The optical engine lens module provided in this application adopts a 1G3P compact architecture consisting of "one glass positive lens and three plastic lenses", and controls its total optical length TTL within an extremely short range of 5.1mm to 5.6mm, thereby directly meeting the core demand of AR and other near-eye display devices for the extreme thinness of the optical system.

[0020] Furthermore, designing the first lens 1 as a "shared lens" whose structural parameters remain unchanged when adapting to MicroLED microdisplays of different resolutions is a key innovation of this solution. This design allows for flexible adaptation to microdisplays of various resolutions without requiring a complete reconstruction of the basic optical architecture; simply by optimizing the structural parameters of the other three plastic lenses in the optical path. This not only improves the versatility, scalability, and development efficiency of the optical design, but also lays a structural foundation for further optimizing image quality and ensuring wide-temperature stability within a limited size of the module while achieving an ultra-short overall length.

[0021] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.

[0023] Figure 1 This is a schematic diagram of the structure and optical path of the optical-mechanical lens module provided in Embodiment 1 of this application; Figure 2 This is a schematic diagram of the structure and optical path of the optical-mechanical lens module provided in Embodiment 2 of this application; Figure 3 This is a schematic diagram of the structure and optical path of the optical-mechanical lens module provided in Embodiment 3 of this application; Figure 4 for Figure 1 The diagram shows a dot matrix of the optical-mechanical lens module. Figure 5 for Figure 1 The field curvature and distortion diagram of the optical-mechanical lens module shown; Figure 6 for Figure 1 The relative illumination diagram of the optical-mechanical lens module is shown. Figure 7a , 7b 7c are respectively Figure 1 The spatial frequency modulation transfer function (MTF) diagrams of the optical-mechanical lens module at 30℃, 10℃, and 50℃ are shown. Figure 8 for Figure 1 The image shows the Through Focus MTF diagram of the optical-mechanical lens module at 30°C. Figure 9 for Figure 1 The image shows the Through Focus MTF diagram of the optical-mechanical lens module at 10°C. Figure 10 for Figure 1The image shows the Through Focus MTF diagram of the optical-mechanical lens module at 50°C. Figure 11 for Figure 2 The diagram shows a dot matrix of the optical-mechanical lens module. Figure 12 for Figure 2 The field curvature and distortion diagram of the optical-mechanical lens module shown; Figure 13 for Figure 2 The relative illumination diagram of the optical-mechanical lens module is shown. Figure 14a , 14b 14c are respectively Figure 2 The spatial frequency modulation transfer function (MTF) diagrams of the optical-mechanical lens module at 30℃, 10℃, and 50℃ are shown. Figure 15 for Figure 2 The image shows the Through Focus MTF diagram of the optical-mechanical lens module at 30°C. Figure 16 for Figure 2 The image shows the Through Focus MTF diagram of the optical-mechanical lens module at 10°C. Figure 17 for Figure 2 The image shows the Through Focus MTF diagram of the optical-mechanical lens module at 50°C. Figure 18 for Figure 3 The diagram shows a dot matrix of the optical-mechanical lens module. Figure 19 for Figure 3 The field curvature and distortion diagram of the optical-mechanical lens module shown; Figure 20 for Figure 3 The relative illumination diagram of the optical-mechanical lens module is shown. Figure 21a , 21b 21c are respectively Figure 3 The spatial frequency modulation transfer function (MTF) diagrams of the optical-mechanical lens module at 30℃, 10℃, and 50℃ are shown. Figure 22 for Figure 3 The image shows the Through Focus MTF diagram of the optical-mechanical lens module at 30°C. Figure 23 for Figure 3 The image shows the Through Focus MTF diagram of the optical-mechanical lens module at 10°C. Figure 24 for Figure 3The image shows the through-focus MTF diagram of the optical-mechanical lens module at 50°C.

[0024] Explanation of reference numerals in the attached figures: 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. MicroLED micro-display. Detailed Implementation

[0025] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0026] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0027] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0028] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0029] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0030] The optical engine lens module and near-eye optical display device provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0031] According to one embodiment of this application, an optical-mechanical lens module is provided, see [link]. Figures 1 to 3 The optical-mechanical lens module comprises a first lens group and a second lens group sequentially along the optical axis from the object side to the image side. The first lens group includes a first lens 1 with positive optical power, and the first lens 1 is a glass lens. The second lens group includes three plastic lenses, which are, sequentially along the optical axis, a second lens 2 with positive optical power, a third lens 3 with negative optical power, and a fourth lens 4 with negative optical power; wherein, the first lens 1 is a common lens that maintains fixed structural parameters when adapting to MicroLED microdisplays 5 with different resolutions; the total optical length (TTL) of the optical-mechanical lens module is 5.1mm ≤ TTL ≤ 5.6mm.

[0032] The optical engine lens module provided in this application is adapted to a projection optical engine system that uses a single green MicroLED microdisplay as the image source. Its typical applications include, but are not limited to, the optical engines of near-eye display devices such as augmented reality (AR) glasses and mixed reality (MR) head-mounted displays. This application does not limit the specific device form that includes this optical engine lens module.

[0033] It should be noted that, Figure 1 , Figure 2 and Figure 3 The accompanying figures illustrate specific optical path structure embodiments of the optical-mechanical lens module of this application when adapted to three different resolution MicroLED microdisplays. These figures collectively demonstrate the core design method proposed in this application: a 1G3P glass-plastic hybrid architecture consisting of "one glass lens with fixed structural parameters and three plastic lenses with adjustable structural parameters." Specifically, the structural parameters of the first lens 1 (glass material) remain fixed, serving as a common reference for the optical-mechanical lens module. Based on this, by specifically adjusting the curvature, thickness, and spacing of the other three plastic lenses, the same basic optical architecture can be flexibly adapted to the display requirements of different resolutions, thereby achieving a balance between high performance, compactness, and good scalability.

[0034] Specifically, Figures 1 to 3 In each diagram, the light path propagates from right to left (i.e., from the image side of the MicroLED microdisplay 5 towards the object side), passing sequentially through the fourth lens 4, the third lens 3, the second lens 2, and the first lens 1. The diagram shows the mirror curvature, optical power distribution, and stop position of each lens, illustrating the propagation direction, convergence, and divergence of light within the lens group.

[0035] Although there are minor adjustments in the specific curvature radius, thickness and spacing of the lenses in the three images, the overall optical path shape, the number and order of the lenses, and the "positive-negative-negative" rear group (second lens group) structure remain consistent. This demonstrates the design concept of adapting to MicroLED microdisplays 5 with different resolutions by fixing the structural parameters of the first lens 1 and optimizing the structural parameters of the other three lenses.

[0036] The following is a detailed description of the four lenses in the optical-mechanical lens module of this application embodiment.

[0037] According to the optical-mechanical lens module provided in the embodiments of this application, its optical path propagation direction is as follows: Figures 1 to 3 As shown. Specifically: from the image side (i.e. Figures 1 to 3The imaging light from the MicroLED microdisplay 5 on the right side first enters and passes through the fourth lens 4 of the second lens group. As the first lens encountered by the light in the optical path, the fourth lens 4, with its negative optical power, can converge the large-angle diverging beam from the image side and undertake the role of aberration pre-correction at the front end.

[0038] After passing through the fourth lens 4, the light enters the third lens 3. The third lens 3 also has negative optical power and works in conjunction with the fourth lens 4 to further control the divergence angle of the light and compensate for and correct specific aberrations (such as field curvature), creating favorable conditions for the subsequent converging optical path.

[0039] Subsequently, the light continues to pass through the second lens 2. The second lens 2 has positive optical power. As the positive lens element in the second lens group, it mainly undertakes the function of converging the light rays that have been gathered by the first two negative lenses. Moreover, due to the characteristic that its material refractive index is lower than that of the negative lenses in the preceding optical path, such as the third lens 3, it can effectively correct the axial chromatic aberration of the optical-mechanical lens module. This is one of the core elements for achieving high image quality imaging.

[0040] Finally, the light rays pass through the first lens 1 and exit to the aperture stop. The first lens 1 is a glass lens with positive optical power. As the last lens before light exits from the entire optical-mechanical lens module, it undertakes the final task of light collimation and aberration balancing. Its stable glass material properties ensure the optical path stability of the optical-mechanical lens module under temperature changes. The light rays corrected by the first lens 1 can exit at a suitable angle and beam shape and enter the aperture stop, completing the transmission of the imaging optical path.

[0041] The optical-mechanical lens module design provided in this application adopts a hybrid optical architecture of one glass lens and three plastic lenses (1G3P). The glass lens (i.e., the first lens 1) located in the first lens group achieves core aberration correction and image quality stability over a wide temperature range, while the three plastic lenses (i.e., the second lens 2, the third lens 3, and the fourth lens 4) in the second lens group effectively control the overall weight and production cost of the optical-mechanical lens module while achieving fine aberration correction and optimizing image field flatness.

[0042] In the optical-mechanical lens module of this application embodiment, all lenses adopt an aspherical design, which provides key design freedom for efficient correction of various aberrations.

[0043] This application proposes that the first lens 1 is a common lens that maintains fixed structural parameters when adapting to MicroLED microdisplays 5 with different resolutions. Specifically, when it is necessary to adapt the optical engine lens module to different pixel numbers (such as 660×880, 720×960, 780×1040, respectively corresponding to...) Figure 1 , Figure 2 and Figure 3 However, when multiple MicroLED microdisplays 5 have the same pixel size (e.g., 2.5μm), all structural parameters of the first lens 1 (a glass positive lens) located at the end of the optical path, such as radius of curvature, center thickness, refractive index, and Abbe number, remain unchanged, serving as a fixed and fundamental part of the entire optical architecture. This design makes the first lens 1 a universal optical element. Based on this optics, by mainly adjusting the structural parameters of the three plastic lenses (i.e., second lens 2, third lens 3, and fourth lens 4) in the second lens group at the front end of the optical path, adaptation and image quality optimization for displays with different resolutions can be achieved. This strategy not only significantly improves the reusability and development efficiency of optical design and reduces the R&D cost and cycle of designing entirely new lenses for different specifications of MicroLED microdisplays, but more importantly, it ensures the stability of the core aberration correction capability and optical power contribution of the optical-mechanical lens module, laying a structural foundation for the performance consistency and adaptation flexibility of the entire optical-mechanical lens module over a wide temperature range.

[0044] The optical engine lens module provided in this application embodiment has an optical total length (TTL) controlled between 5.1mm and 5.6mm. This extremely short size of ≤5.6mm corresponds to the urgent need for thinner and smaller sizes in near-eye display devices such as AR—the shorter the optical engine lens module, the thinner and lighter the entire device.

[0045] The optical engine lens module provided in this application adopts a 1G3P compact architecture consisting of "one glass positive lens and three plastic lenses", and controls its total optical length TTL within an extremely short range of 5.1mm to 5.6mm, thereby directly meeting the core demand of AR and other near-eye display devices for the extreme thinness of the optical system.

[0046] Furthermore, designing the first lens 1 as a "shared lens" whose structural parameters remain unchanged when adapting to MicroLED microdisplays of different resolutions is a key innovation of this solution. This design allows for flexible adaptation to microdisplays of various resolutions without requiring a complete reconstruction of the basic optical architecture; simply by optimizing the structural parameters of the other three plastic lenses in the optical path. This not only improves the versatility, scalability, and development efficiency of the optical design, but also lays a structural foundation for further optimizing image quality and ensuring wide-temperature stability within a limited size of the module while achieving an ultra-short overall length.

[0047] In some examples of this application, the refractive index Nd1 of the first lens 1 is 1.58 ≤ Nd1 ≤ 1.6. The refractive index Nd2 of the second lens 2 is 1.6 ≤ Nd2 ≤ 1.7. The refractive indices Nd3 and Nd4 of the third lens 3 and the fourth lens 4 satisfy: 1.65 ≤ Nd3 and Nd4 ≤ 1.68, and Nd2 is less than Nd3 and Nd4.

[0048] In this example of the application, the refractive indices of the four lens materials constituting the optical-mechanical lens module were designed and coordinated. This is the key material basis for achieving high imaging quality within an extremely short optical length of the optical-mechanical lens module, especially for effectively correcting chromatic aberration and maintaining temperature stability.

[0049] In the specific optical path, see Figures 1 to 3 Light rays from the image side first pass through the fourth lens 4 of the second lens group. The fourth lens 4 is designed with negative optical power, and its material refractive index is set in the range of 1.65 to 1.68. This higher refractive index is beneficial for controlling the optical path with a more compact curvature when initially focusing large-angle beams, and also participates in subsequent chromatic aberration correction.

[0050] The light then passes through the third lens 3, which belongs to the second lens group. The third lens 3 also has negative optical power, and its refractive index is set in the range of 1.65 to 1.68. Its consistency with the refractive index of the fourth lens 4 is beneficial for the two to work together as a negative lens group, establishing a stable basis for the balance of aberrations (such as field curvature).

[0051] The light continues to propagate to the second lens 2 of the second lens group. The second lens 2 is the only lens in the second lens group with positive optical power, and its refractive index is designed to be in the range of 1.6 to 1.7. Preferably, the refractive index of the second lens 2 should be lower than that of the adjacent third lens 3. This refractive index relationship—lower for positive lenses and higher for negative lenses—is one of the design principles for achieving excellent chromatic aberration correction in this application. Specifically, the positive-power second lens 2 and the negative-power third lens 3 work together through the difference in their refractive index and Abbe number (characterizing dispersion capability). While contributing the required optical power, they can effectively counteract the focus shift caused by different wavelengths, thereby significantly suppressing axial chromatic aberration of the module and ensuring clear imaging within the operating wavelength range.

[0052] Finally, the light rays pass through the first lens 1 in the first lens group and exit. As the only glass lens in the entire optical-mechanical lens module, its refractive index is designed to be in the relatively low range of 1.58 to 1.6. Choosing this type of glass material with a high Abbe number (low dispersion) not only provides the optical-mechanical lens module with the final collimation and aberration balance capabilities, but its excellent thermal stability is also key to ensuring consistent image quality across a wide temperature range for the entire optical-mechanical lens module.

[0053] In summary, this refractive index step and material combination (glass and plastic combination) planned along the optical path direction is one of the core guarantees for achieving excellent optical performance of the optical scheme of this application under strict optical length dimension constraints.

[0054] In some examples of this application, the center thickness of the second lens 2 is T2, the center thickness of the third lens 3 is T3, and the center thickness of the fourth lens 4 is T4, and satisfies: 0.5 < (T2 + T3) / T4 < 1.0.

[0055] In this example of the application, the center thickness relationship of the three plastic lenses in the second lens group follows a specific design constraint: the center thickness T2 of the second lens 2, the center thickness T3 of the third lens 3, and the center thickness T4 of the fourth lens 4 satisfy the ratio 0.5 < (T2 + T3) / T4 < 1.0. This relationship is a key structural design established to rationally allocate the physical space of the lenses and coordinately control the optical path and aberrations, under the premise that the total optical length TTL is controlled within the extremely short range of 5.1 mm to 5.6 mm.

[0056] The parameter relationship 0.5 < (T2 + T3) / T4 < 1.0 in this example is a core structural design principle of the second mirror group in this application. Specifically: From the perspective of optical path propagation, the imaging ray first passes through the fourth lens 4 and the third lens 3, which have negative optical power, and finally through the second lens 2, which has positive optical power. The center thickness T4 of the fourth lens 4 is the first physical thickness experienced by the light ray after entering the optical-mechanical lens module, and its size has a fundamental impact on the lens curvature design, optical power realization, and initial aberration correction capability. The sum of the center thicknesses of the third lens 3 and the second lens 2 (T2+T3) represents the subsequent optical path length accumulated by the light ray during the main aberration correction and optical path transition. Constraining the value of (T2+T3) / T4 within the range of 0.5 to 1.0 is essentially an optimized allocation and balanced control of the internal space of the second lens group under the constraint of an extremely short total optical length (TTL≤5.6mm).

[0057] The proportions in this example ensure that the negative lens (fourth lens 4) in the second lens group, which is responsible for initial convergence and aberration pre-correction, has sufficient center thickness (T4) to stabilize the optical path, while avoiding the sum of the center thicknesses (T2+T3) of the two lenses in the subsequent optical path (third lens 3 with negative optical power and second lens 2 with positive optical power) being too large and excessively crowding out the total optical length TTL, thereby leaving the necessary correction space for the glass lenses in the first lens group.

[0058] The reasonable thickness ratio in this example helps to coordinate the propagation of light within the second lens group. Combined with the optical power, refractive index, and aspherical coefficient of each lens in the lens group, it effectively manages aberrations such as field curvature and astigmatism, laying the foundation for a smooth transition of light to the first lens group and the final optimization of image quality.

[0059] Furthermore, the thickness constraint in this example also prevents any lens from being too thin (which may lead to molding difficulties or insufficient strength) or too thick (which may introduce internal stress or deformation), thus improving the structural stability of the second lens group and the feasibility of the injection molding process.

[0060] In one specific embodiment of this application, see [reference needed]. Figure 1 The optical-mechanical lens module is adapted to a MicroLED micro-display 5 with a resolution of 660×880. At this time, the center thickness of each lens in the second lens group satisfies: 0.8<(T2+T3) / T4<1.0.

[0061] In another specific embodiment of this application, see [link to application]. Figure 2 The optical-mechanical lens module is adapted to a MicroLED micro-display 5 with a resolution of 720×960. At this time, the center thickness of each lens in the second lens group satisfies: 0.8 < (T2+T3) / T4 < 1.0.

[0062] In yet another specific embodiment of this application, see [link to relevant documentation]. Figure 3 The optical-mechanical lens module is adapted to a MicroLED micro-display 5 with a resolution of 780×1040. At this time, the center thickness of each lens in the second lens group satisfies: 0.5<(T2+T3) / T4<1.0.

[0063] The ratio range of 0.5 < (T2 + T3) / T4 < 1.0 constrained in this example is a reasonable generalization and overarching coverage of the different ratio relationships used in the three specific embodiments described above. This ratio range encompasses the optical optimization adjustments made to adapt to displays of different resolutions, thereby ensuring that the beneficial effects of compact layout, aberration balance, and structural stability expected in this application can be achieved in various specific design scenarios, and providing the necessary flexibility for actual optical design.

[0064] In some examples of this application, the center thickness T1 of the first lens 1 satisfies 14.6% ≤ T1 / TTL ≤ 15.8%. The center thicknesses T2, T3, and T4 of the second lens 2, the third lens 3, and the fourth lens 4 respectively satisfy: 12.05% ≤ T2 / TTL ≤ 14.8%, 5.5% ≤ T3 / TTL ≤ 6.6%, and 22.94% ≤ T4 / TTL ≤ 30.6%.

[0065] In this example of the application, the percentage of the center thickness of the four lenses in the optical engine lens module to the total optical length (TTL) was optimized. This is a key structural parameter design for achieving efficient space utilization, optical path control, and aberration balance in the optical solution of this application under the constraint of an extremely short total optical length (TTL≤5.6mm). The specific scope is as follows: The center thickness T1 of the first lens 1 satisfies: 14.6%≤T1 / TTL≤15.8%.

[0066] The center thickness T2 of the second lens 2 satisfies: 12.05%≤T2 / TTL≤14.8%.

[0067] The center thickness T3 of the third lens 3 satisfies: 5.5%≤T3 / TTL≤6.6%.

[0068] The center thickness T4 of the fourth lens 4 satisfies: 22.94%≤T4 / TTL≤30.6%.

[0069] Specifically, the imaging light rays emanating from the image side first enter the fourth lens 4, which has the largest center thickness T4 / percentage (22.94%~30.6%). This provides sufficient optical path depth for the first negative lens in the optical path, enabling it to effectively perform initial convergence and aberration pre-correction for the incident large-angle diverging beam. Subsequently, the light rays pass through the third lens 3, which has the smallest center thickness / percentage (only 5.5%~6.6%). This helps achieve a smooth transition of the optical path and compensation for specific aberrations within a compact space. Next, the light rays pass through the second lens 2, which has a relatively large center thickness / percentage (12.05%~14.8%). This positive lens needs sufficient thickness to converge the light rays and correct chromatic aberration. Finally, the light rays enter the first lens 1 of the first lens group (14.6%~15.8%). Its suitable center thickness T1 / percentage ensures that this glass lens provides final aberration balance and collimation while maintaining the overall size and weight control of the optical-mechanical lens module.

[0070] The proportions in this example, while compressing the total optical length (TTL), ensure that each lens has a reasonable thickness while contributing its specific optical function (such as divergence of negative lenses, convergence of positive lenses, and stability of glass lenses), thus guaranteeing the feasibility of optical performance. At the same time, these ranges avoid problems such as manufacturing difficulties, insufficient strength, or difficulty in controlling the surface shape caused by excessively thin lenses, as well as the drawbacks of excessive thickness, such as additional weight and internal stress, achieving a balance between optical performance, structural reliability, and manufacturability.

[0071] The percentage range provided in this example covers several specific implementations optimized for different resolution displays such as 660×880, 720×960, and 780×1040.

[0072] In one specific embodiment of this application, see [reference needed]. Figure 1 The optical-mechanical lens module is adapted to a MicroLED micro-display 5 with a resolution of 660×880. At this time, the center thickness T1 of the first lens 1 satisfies T1 / TTL of 15.8%, and the center thicknesses T2, T3, and T4 of the second lens 2, the third lens 3, and the fourth lens 4 satisfy T2 / TTL of 14.8%, T3 / TTL of 6.6%, and T4 / TTL of 25.7%, respectively.

[0073] In another specific embodiment of this application, see [link to application]. Figure 2 The optical-mechanical lens module is adapted to a MicroLED micro-display 5 with a resolution of 720×960. At this time, the center thickness T1 of the first lens 1 satisfies T1 / TTL of 15.75%, and the center thicknesses T2, T3, and T4 of the second lens 2, the third lens 3, and the fourth lens 4 satisfy T2 / TTL of 14.3%, T3 / TTL of 6.2%, and T4 / TTL of 22.94%, respectively.

[0074] In yet another specific embodiment of this application, see [link to relevant documentation]. Figure 3 The optical-mechanical lens module is adapted to a MicroLED micro-display 5 with a resolution of 780×1040. At this time, the center thickness T1 of the first lens 1 satisfies T1 / TTL of 14.6%, and the center thicknesses T2, T3, and T4 of the second lens 2, the third lens 3, and the fourth lens 4 satisfy T2 / TTL of 12.05%, T3 / TTL of 5.5%, and T4 / TTL of 30.6%, respectively.

[0075] In some examples of this application, the maximum aperture of all lenses in the optical-mechanical lens module is D0, and satisfies: 0.2 < D0 / TTL < 1.0.

[0076] In this example of the application, the optical-mechanical lens module satisfies a key proportional constraint: the maximum aperture of all lenses is D0, and its ratio to the total optical length (TTL) satisfies 0.2 < D0 / TTL < 1.0. This parameter relationship is one of the design principles that ensures the optical-mechanical lens module of this application achieves high optical performance while meeting the compactness requirement, which will be explained in detail below.

[0077] In this example, the ratio 0.2 < D0 / TTL < 1.0 defines the proportional relationship of the optical-mechanical lens module in both radial (aperture) and axial (length) dimensions. The lower limit constraint of D0 / TTL > 0.2 ensures that the optical-mechanical lens module has a minimum effective aperture that matches its total optical length, thus providing the necessary physical basis for achieving sufficient light intake (F-number) and target imaging field of view.

[0078] The upper limit constraint of D0 / TTL < 1.0, in terms of physical form, stipulates that the maximum aperture of the optical engine lens module must be smaller than its total optical length. This prevents the optical design from becoming bulky and short in pursuit of other performance characteristics, and instead drives it to be optimized towards a more compact axial (vertical) and controlled radial (lateral) dimensions. This design is one of the key design features for achieving a thinner and lighter overall design.

[0079] The maximum aperture D0 is determined by the edge field of view rays, and its size is directly related to the field of view and relative aperture (F number) of the optical-mechanical lens module. Under the premise that the total optical length TTL is strictly limited to ≤5.6mm, controlling D0 / TTL within this range is essentially a coordinated design and balance of the radial dimension and axial length of the optical-mechanical lens module under a tight size constraint.

[0080] In some examples of this application, the first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 are all aspherical lenses with a conic coefficient of -20 to 20.

[0081] In this example of the application, the first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 are all aspherical, and the conic constant of each aspherical surface is limited to the range of -20 to 20.

[0082] Designing all lens surfaces as aspherical provides significant design freedom for correcting various aberrations (such as spherical aberration, coma, astigmatism, and field curvature) within a compact optical architecture using only four lenses. Constraining the conic coefficient within the aforementioned range represents a balanced design principle achieved between manufacturing feasibility and optical performance optimization.

[0083] Specifically, the range in this example is set primarily for two considerations: First, it ensures sufficient flexibility in the aspherical surface shape variation, allowing optical designs to finely adjust the surface curvature according to the specific position and function of each lens in the optical path (e.g., the fourth lens focusing the diverging beam, the second lens correcting chromatic aberration, and the first lens achieving final collimation and balance), thereby efficiently optimizing the optical path and improving image quality. Second, this range also takes into account the manufacturability of aspherical lenses (especially plastic lenses), avoiding excessively steep or complex surface shapes due to excessively large absolute values ​​of the conic coefficient, which would increase the difficulty and cost of precision injection molding or glass molding processes.

[0084] In one specific embodiment of this application, see [reference needed]. Figure 1 The optical engine lens module is adapted to a MicroLED micro-display 5 with a resolution of 660×880. At this time, the first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 are all aspherical lenses with a conic coefficient of -20 to 20.

[0085] In another specific embodiment of this application, see [link to application]. Figure 2 The optical engine lens module is adapted to a MicroLED micro-display 5 with a resolution of 720×960. At this time, the first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 are all aspherical lenses with a conic coefficient of -20 to 20.

[0086] In yet another specific embodiment of this application, see [link to relevant documentation]. Figure 3 The optical engine lens module is adapted to a MicroLED micro-display 5 with a resolution of 780×1040. At this time, the first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 are all aspherical lenses with a conic coefficient of -16 to 20.

[0087] In some examples of this application, the optical-mechanical lens module satisfies the following conditions: The air gap between any two adjacent lenses shall not be less than 0.080 mm; The center thickness of any lens shall not be less than 0.305 mm; The distance from the image side surface to the image plane of the fourth lens 4 is not less than 0.5 mm.

[0088] In this example of the application, these conditions are physical guarantees that ensure the compact optical design can be manufactured and assembled stably and reliably, and maintain consistent performance over long-term use.

[0089] Specifically, the air gap between any two adjacent lenses must be no less than 0.080 mm. This constraint applies to the entire optical path from the image side to the object side, specifically between the fourth lens 4 and the third lens 3, between the third lens 3 and the second lens 2, and between the second lens 2 and the first lens 1. This constraint serves two main purposes: first, to prevent direct contact or friction between the optical surfaces of the lenses due to material thermal expansion or minor cumulative assembly errors during assembly, thus preventing lens scratches, stress introduction, or optical axis misalignment; second, to provide the necessary operating space and tolerance for actual lens barrel structure design, spacer ring positioning, or dispensing processes, ensuring the alignment accuracy and long-term stability of the optical centers of each lens.

[0090] Secondly, the center thickness of any lens must be no less than 0.305 mm. This requirement ensures that every lens, whether it is the first lens 1 made of glass or the second to fourth lenses 4 made of plastic, has the center thickness required to meet basic manufacturing processes and structural strength. For the three plastic lenses, this minimum center thickness helps maintain uniform material flow and consistent cooling during injection molding, effectively preventing defects such as shrinkage marks, warping, or incomplete filling caused by excessively thin walls, and ensuring surface accuracy. For the glass lenses, it provides reliable substrate allowance for precision machining processes such as cutting, grinding, and polishing, and ensures sufficient mechanical strength for subsequent coating, clamping, and use.

[0091] The distance from the image-side surface of the fourth lens 4 to the image plane is not less than 0.5 mm. This design ensures a necessary safety gap between the fourth lens 4 and the display screen, and its beneficial effects are mainly reflected in the following aspects: It prevents the lens from directly contacting the display screen surface during assembly or impact, protecting optical components and display units from mechanical damage. It provides space to accommodate minor deformations caused by differences in the thermal expansion coefficients of different materials, maintaining the thermal stability of the imaging focal plane. It facilitates the integration of optical components such as display screen protective covers or filters, improving mass production feasibility and reliability.

[0092] In some examples of this application, the effective focal length f1 of the first lens 1 ranges from 1 mm to 5 mm. The effective focal length f2 of the second lens 2 ranges from 1 mm to 5 mm. The effective focal length f3 of the third lens 3 ranges from -5 mm to -1 mm. The effective focal length f4 of the fourth lens 4 ranges from -150 mm to -100 mm, -20 mm to -10 mm, or -10 mm to -1 mm.

[0093] In this example of the application, in order to achieve the synergistic goal of large field of view, high image quality and multi-resolution adaptation under extremely short optical total length TTL, the effective focal lengths of the four lenses were systematically allocated.

[0094] The fourth lens 4, serving as the first lens, has an effective focal length f4 with negative optical power designed to be available in three selectable ranges: -150mm to -100mm, -20mm to -10mm, and -10mm to -1mm. These three ranges correspond to optimized selections for adapting to MicroLED displays with different resolutions, such as 660×880, 720×960, and 780×1040, respectively. See [link to relevant documentation] for details. Figure 1 , Figure 2 and Figure 3 As shown. For example, a longer negative focal length allows for a smoother initial convergence of light, while a shorter negative focal length provides greater control over light to accommodate different image sizes and aberration balance requirements.

[0095] The third lens 3 also has negative optical power, and its effective focal length f3 is limited to a short negative range of -5mm to -1mm. This setting allows it to work in conjunction with the fourth lens 4 to form a negative lens group, effectively converging large-angle diverging beams and focusing on correcting aberrations such as astigmatism and field curvature, creating favorable conditions for the light to transition to the subsequent positive lens.

[0096] The second lens 2, being the only lens with positive optical power in the second lens group, has an effective focal length f2 set in the positive range of 1mm to 5mm. Its main function is to converge the light rays pre-converged by the first two negative lenses. Crucially, it works in conjunction with the third lens 3, a negative optical power lens with a higher refractive index, to form an achromatic combination through matching optical power with material dispersion, becoming a key element in correcting axial chromatic aberration in the optical engine lens module.

[0097] The first lens 1, as the glass lens in the first lens group, has positive optical power, and its effective focal length f1 is also set in the positive range of 1mm to 5mm. Located at the end of the optical path, the first lens 1 is responsible for the final collimation of the light beam and the balancing of module aberrations. Its effective focal length f1, in conjunction with the second lens 2, determines the total effective focal length of the entire optical-mechanical lens module to be 4.3mm to 5.0mm, ensuring that the outgoing light beam enters the aperture at a suitable angle and shape.

[0098] In some examples of this application, the effective focal length f of the optical-mechanical lens module is 4.3mm to 5.0mm, and the field of view (FOV) of the optical-mechanical lens module is not less than 35° when the working wavelength is 502nm to 552nm.

[0099] In this example of the application, the effective focal length f of the optical-mechanical lens module is 4.3mm to 5.0mm. This relatively short focal length range is a result of maintaining the compactness of the optical-mechanical lens module while achieving an extremely short total optical length (TTL) of 5.1mm to 5.6mm. The short focal length design enables the optical-mechanical lens module to have a strong focusing ability for light emitted from tiny pixels (2.5μm) on, for example, a microdisplay, which is the basis for achieving high angular resolution (high PPD) and also creates favorable conditions for subsequent pupil matching with light guide devices.

[0100] The operating wavelength range is 502nm~552nm for a single green light, which is a proprietary optical design of this application for the spectral characteristics of a single green MicroLED light source.

[0101] A full field of view (DFOV) of not less than 35° is a key performance indicator for the optical-mechanical lens module of this application, enabling it to provide a wide and immersive visual experience while achieving a compact design. Achieving this field of view level within the constraints of a short focal length of only 4.3mm to 5.0mm and a total optical length not exceeding 5.6mm demonstrates the optical-mechanical lens module's efficient large-angle light reception and control capabilities. This field of view range can significantly expand the user's field of view coverage, effectively enhancing the immersive experience of near-eye display devices (such as AR / MR glasses).

[0102] In this example of the application, the optical-mechanical lens module further includes a MicroLED microdisplay 5 disposed at the image plane position, and the distance from the image side of the fourth lens 4 near the MicroLED microdisplay 5 to the light-emitting surface of the MicroLED microdisplay 5 is not less than 0.5mm; the pixel size of the MicroLED microdisplay 5 is 2.5μm, and the resolution includes 660×880, 720×960 or 780×1040.

[0103] In this example of the application, the description of the optical-mechanical lens module further includes the specific configuration of the image source—the MicroLED microdisplay 5—that works in conjunction with it.

[0104] Specifically: First, it is clarified that the distance from the image-side surface (the surface near the display screen) of the fourth lens 4 to the light-emitting surface of the MicroLED microdisplay 5 is not less than 0.5mm. This setting of the working distance has several benefits: First, it provides necessary physical integration space for potential components on the microdisplay surface, such as protective covers, infrared cut-off filters, or optical adhesive layers, preventing mechanical interference; second, it compensates for the slight relative displacement between the lens assembly (composed of the first lens 1 to the fourth lens 4) and the microdisplay caused by temperature changes due to differences in the coefficients of thermal expansion of the materials, maintaining the stability of the imaging focal plane.

[0105] Secondly, the core parameters of the compatible MicroLED microdisplay were clarified: the pixel size is 2.5μm, and the resolution covers 660×880, 720×960, or 780×1040, respectively (see [link to relevant documentation]). Figure 1 , Figure 2 and Figure 3 The pixel size is the design basis for the optical-mechanical lens module to achieve high-resolution (high MTF) imaging. The three resolution specifications directly correspond to the feasibility of adapting to the design goal of microdisplays with different resolutions. This specifically reflects the core advantage of the "fixed first lens 1, fine-tuned second lens group" architecture proposed in this application: while maintaining the core optical performance and optical stability of the optical-mechanical lens module, by specifically optimizing the structural parameters of the lenses in the second lens group, it is possible to flexibly adapt to different resolution display needs, from basic to higher levels.

[0106] Figures 1 to 3 The diagram shows the optical architecture and optical path of the optical-mechanical lens module of this application. This module consists of a glass aspherical lens (first lens 1) and three plastic aspherical lenses (second to fourth lenses 4). In this optical structure design, the structural parameters of the glass aspherical lens (first lens 1) are first fixed, serving as a common reference for the optical-mechanical lens module. Subsequently, by fine-tuning the curvature, thickness, and spacing of the three plastic aspherical lenses (second to fourth lenses 4), the optical-mechanical lens module maintains excellent imaging quality within a wide temperature range of 10℃ to 50℃, while keeping the total optical length (TTL) within 5.6mm and the diagonal field of view (DFOV) at 35°.

[0107] The following describes the optical-mechanical lens module provided in this application in detail through Examples 1 to 3.

[0108] Example 1 The optical structure and optical path diagram of the optical engine lens module provided in this embodiment 1 are as follows: Figure 1 As shown, the optical engine lens module includes a first lens group, a second lens group, and a MicroLED microdisplay 5, sequentially from the object side to the image side.

[0109] The first lens group consists of a first lens 1 with positive optical power, and the center thickness T1 of the first lens 1 accounts for 15.8% of the total optical length TTL.

[0110] The second lens group consists of three lenses arranged sequentially from the object side to the image side: a second lens 2 with positive optical power, a second lens 3 with negative optical power, and a fourth lens 4 with negative optical power. The center thickness T2 of the second lens 2 accounts for 14.8% of the total optical length TTL, the center thickness T3 of the third lens 3 accounts for 6.6% of the total optical length TTL, and the center thickness T3 of the fourth lens 4 accounts for 25.7% of the total optical length TTL.

[0111] In terms of material configuration, the first lens 1 is a glass aspherical lens, while the second lens 2, the third lens 3, and the fourth lens 4 are all plastic aspherical lenses, thus forming a "3P1G" glass-plastic hybrid aspherical lens group structure. The conic coefficient range of these four lenses is -20 to 20.

[0112] The effective focal length f1 of the first lens 1 ranges from 1mm to 5mm, the effective focal length f2 of the second lens 2 ranges from 1mm to 5mm, the effective focal length f3 of the third lens 3 ranges from -5mm to -1mm, and the effective focal length f4 of the fourth lens 4 ranges from -150mm to -100mm.

[0113] See Figure 1 The design parameters of the optical-mechanical lens module shown are as follows: effective focal length of 4.36mm, entrance pupil diameter (EPD) of 2.5mm, entrance pupil distance of 0.2mm, and optimized for MicroLED microdisplay 5 with a pixel size of 2.5μm. The operating wavelength of the optical-mechanical lens module is limited to single green light from 502nm to 552nm. Its horizontal and vertical field of view are 28.3° and 21.4°, respectively, corresponding to a diagonal field of view (DFOV) of 35°, and the image plane size is 2.2mm × 1.65mm. With this configuration, the angular resolution (PPD) of the optical-mechanical lens module reaches 31, and the principal ray angle of incidence (CRA) is 16.71°. The optical parameters of the optical-mechanical lens module are shown in Tables 1 to 3 listed below.

[0114] Table 1: Optical parameters of the optical-mechanical lens module at an ambient temperature of 30℃

[0115] Table 2: Optical parameters of the optical-mechanical lens module at an ambient temperature of 10℃

[0116] Table 3: Optical parameters of the optical-mechanical lens module at an ambient temperature of 50℃

[0117] The optical performance of the optical-mechanical lens module provided in Embodiment 1 is as follows: Figures 4 to 10As shown: Figure 4 This is a dot diagram of the optical engine lens module. Figure 5 It is a field curvature and distortion diagram of the optical engine lens module. Figure 6 This is a relative illumination diagram of the optical engine lens module. Figure 7a , 7b Figures 7 and 7c show the spatial frequency modulation transfer function (MTF) of the optical-mechanical lens module at 30℃, 10℃, and 50℃, respectively. Figures 8 to 10 The images show Through Focus MTF (defocus MTF) plots of the optical engine lens module at 30℃, 10℃, and 50℃.

[0118] See Figure 4 As shown in the dot plot, the root mean square (RMS) radius of the image point of the optical-mechanical lens module in Example 1 is less than 3μm in each field of view, indicating that it has excellent imaging concentration and detail resolution potential.

[0119] See Figure 5 The field curvature and distortion diagrams show that the maximum distortion of the optical-mechanical lens module in Example 1 occurs at the edge of the field of view, and its absolute value is controlled within 5%, ensuring the geometric fidelity of the image.

[0120] See Figure 6 The relative illumination diagram shows that, at a maximum field of view of 35°, the relative illumination of the edge field of view of the optical-mechanical lens module in Example 1 can reach 1.0. This indicates that the optical-mechanical lens module has excellent illumination uniformity, which can ensure that the brightness of the edge and center of the image is highly consistent and effectively avoid vignetting.

[0121] Figure 7a , 7b Figures 7 and 7c show the modulation transfer function (MTF) curves of the optical-mechanical lens module at 30°C, 10°C, and 50°C, respectively. At spatial frequencies up to 200 lp / mm, the MTF values ​​of the optical-mechanical lens module in Example 1 are all greater than 0.6 for each field of view, demonstrating that it can maintain excellent resolution and contrast over a wide temperature range.

[0122] Figures 8 to 10 The Through Focus MTF chart further demonstrates that, within the operating temperature range, the optical transfer function (OTF) coefficient of the optical-mechanical lens module of Embodiment 1 remains stable above 0.6 in the visible light band. This comprehensively verifies that the optical-mechanical lens module of Embodiment 1 can still achieve stable imaging characteristics with high resolution and high contrast under harsh environmental conditions.

[0123] Example 2 The optical-mechanical lens module provided in this embodiment 2 is described in [reference]. Figure 2 Its optical architecture is basically the same as that of Example 1, except that: The center thickness T1 of the first lens 1 accounts for 15.75% of the total optical length TTL, the center thickness T2 of the second lens 2 accounts for 14.3% of the total optical length TTL, the center thickness T3 of the third lens 3 accounts for 6.2% of the total optical length TTL, and the center thickness T3 of the fourth lens 4 accounts for 22.94% of the total optical length TTL.

[0124] The effective focal length f1 of the first lens 1 ranges from 1mm to 5mm, the effective focal length f2 of the second lens 2 ranges from 1mm to 5mm, the effective focal length f3 of the third lens 3 ranges from -5mm to -1mm, and the effective focal length f4 of the fourth lens 4 ranges from -20mm to -10mm.

[0125] See Figure 2 The optical-mechanical lens module shown has the following key design parameters: an effective focal length of 4.57 mm, an entrance pupil diameter (EPD) of 2.5 mm, an entrance pupil distance of 0.2 mm, and is optimized for a MicroLED microdisplay 5 with a pixel size of 2.5 μm. The operating wavelength of the optical-mechanical lens module is limited to single green light from 502 nm to 552 nm. Its horizontal and vertical field of view are 28.3° and 21.4°, respectively, corresponding to a diagonal field of view (DFOV) of 35°, and an image size of 2.4 mm × 1.8 mm. With this configuration, the optical-mechanical lens module achieves an angular resolution (PPD) of 34 and a principal ray angle of incidence (CRA) of 15.85°. The optical parameters of the optical-mechanical lens module are shown in Tables 4 to 6 below.

[0126] Table 4: Optical parameters of the optical-mechanical lens module at an ambient temperature of 30℃

[0127] Table 5: Optical parameters of the optical-mechanical lens module at an ambient temperature of 10℃

[0128] Table 6: Optical parameters of the optical-mechanical lens module at an ambient temperature of 50℃

[0129] The optical performance of the optical-mechanical lens module provided in Embodiment 2 is as follows: Figures 11 to 17 As shown: Figure 11 This is a dot diagram of the optical engine lens module. Figure 12 It is a field curvature and distortion diagram of the optical engine lens module. Figure 13 This is a relative illumination diagram of the optical engine lens module. Figure 14a , 14b14c and 14c are the spatial frequency modulation transfer function (MTF) graphs of the optical engine lens module at 30℃, 10℃, and 50℃, respectively. Figures 15 to 17 The images show Through Focus MTF (defocus MTF) plots of the optical engine lens module at 30℃, 10℃, and 50℃.

[0130] See Figure 11 As shown in the dot plot, the root mean square (RMS) radius of the image point of the optical-mechanical lens module in Example 2 is less than 3μm in each field of view, indicating that it has excellent imaging concentration and detail resolution potential.

[0131] See Figure 12 The field curvature and distortion diagrams show that the maximum distortion of the optical-mechanical lens module in Example 2 occurs at the edge of the field of view, and its absolute value is controlled within 5%, ensuring the geometric fidelity of the image.

[0132] See Figure 13 The relative illuminance diagram shows that, at a maximum field of view of 35°, the relative illuminance of the optical-mechanical lens module at the edge of the field of view in Example 2 is still higher than 0.8. This indicates that the optical-mechanical lens module has excellent illuminance uniformity, which can ensure that the brightness of the edge and center of the image is highly consistent and effectively avoids vignetting.

[0133] Figure 14a , 14b Figures 14c and 14c show the modulation transfer function (MTF) curves of the optical-mechanical lens module at 30°C, 10°C, and 50°C, respectively. At spatial frequencies up to 200 lp / mm, the MTF values ​​of the optical-mechanical lens module in Example 2 are all greater than 0.6 for each field of view, demonstrating that it can maintain excellent resolution and contrast over a wide temperature range.

[0134] Figures 15 to 17 The Through Focus MTF chart further demonstrates that, within the operating temperature range, the optical transfer function (OTF) coefficient of the optical-mechanical lens module of Embodiment 2 remains stable above 0.6 in the visible light band. This comprehensively verifies that the optical-mechanical lens module of Embodiment 2 can still achieve stable imaging characteristics with high resolution and high contrast under harsh environmental conditions.

[0135] Example 3 The optical-mechanical lens module provided in this embodiment 3 is described in [reference]. Figure 3 Its optical architecture belongs to the same category as that of Embodiments 1 and 2, with the core difference being: The center thickness T1 of the first lens 1 accounts for 14.6% of the total optical length TTL, the center thickness T2 of the second lens 2 accounts for 12.05% of the total optical length TTL, the center thickness T3 of the third lens 3 accounts for 5.5% of the total optical length TTL, and the center thickness T3 of the fourth lens 4 accounts for 30.6% of the total optical length TTL.

[0136] The effective focal length f1 of the first lens 1 ranges from 1mm to 5mm, the effective focal length f2 of the second lens 2 ranges from 1mm to 5mm, the effective focal length f3 of the third lens 3 ranges from -5mm to -1mm, and the effective focal length f4 of the fourth lens 4 ranges from -10mm to -1mm.

[0137] The conic coefficient of these four lenses ranges from -16 to 20.

[0138] See Figure 3 The optical-mechanical lens module shown has the following key design parameters: an effective focal length of 5.05 mm, an entrance pupil diameter (EPD) of 2.5 mm, an entrance pupil distance of 0.2 mm, and is optimized for a MicroLED microdisplay 5 with a pixel size of 2.5 μm. The operating wavelength of the optical-mechanical lens module is limited to single green light from 502 nm to 552 nm. Its horizontal and vertical field of view are 28.3° and 21.4°, respectively, corresponding to a diagonal field of view (DFOV) of 35°, and an image size of 2.6 mm × 1.95 mm. With this configuration, the optical-mechanical lens module achieves an angular resolution (PPD) of 37 and a principal ray angle of incidence (CRA) of 14.37°. The optical parameters of the optical-mechanical lens module are shown in Tables 7 to 9 below.

[0139] Table 7: Optical parameters of the optical-mechanical lens module at an ambient temperature of 30℃

[0140] Table 8: Optical parameters of the optical-mechanical lens module at an ambient temperature of 10℃

[0141] Table 9: Optical parameters of the optical-mechanical lens module at an ambient temperature of 50℃

[0142] The optical performance of the optical-mechanical lens module provided in Embodiment 3 is as follows: Figures 18 to 24 As shown: Figure 18 This is a dot diagram of the optical engine lens module. Figure 19 It is a field curvature and distortion diagram of the optical engine lens module. Figure 20 This is a relative illumination diagram of the optical engine lens module. Figure 21a ,21b 21c and 21c are the spatial frequency modulation transfer function (MTF) graphs of the optical-mechanical lens module at 30℃, 10℃, and 50℃, respectively. Figures 22 to 24 The images show Through Focus MTF (defocus MTF) plots of the optical engine lens module at 30℃, 10℃, and 50℃.

[0143] See Figure 18 As shown in the dot plot, the root mean square (RMS) radius of the image point of the optical-mechanical lens module in Example 3 is less than 3μm in each field of view, indicating that it has excellent imaging concentration and detail resolution potential.

[0144] See Figure 19 The field curvature and distortion diagrams show that the maximum distortion of the optical-mechanical lens module in Example 3 occurs at the edge of the field of view, and its absolute value is controlled within 10%, ensuring the geometric fidelity of the image.

[0145] See Figure 20 The relative illuminance diagram shows that, at a maximum field of view of 52°, the relative illuminance of the optical-mechanical lens module at the edge of the field of view in Example 3 is still higher than 0.9. This indicates that the optical-mechanical lens module has excellent illuminance uniformity, which can ensure that the brightness of the edge and center of the image is highly consistent and effectively avoids vignetting.

[0146] Figure 21a , 21b Figures 21c and 21c respectively show the modulation transfer function (MTF) curves of the optical-mechanical lens module at 30°C, 10°C, and 50°C. At spatial frequencies up to 200 lp / mm, the MTF values ​​of the optical-mechanical lens module in Example 3 are all greater than 0.6 for each field of view, demonstrating that it can maintain excellent resolution and contrast over a wide temperature range.

[0147] Figures 22 to 24 The Through Focus MTF (Out-of-Focus MTF) plot further demonstrates that, within the operating temperature range, the optical transfer function (OTF) coefficient of the optical-mechanical lens module of Embodiment 3 remains stable above 0.6 in the visible light band. This comprehensively verifies that the optical-mechanical lens module of Embodiment 3 can still achieve stable imaging characteristics with high resolution and high contrast under harsh environmental conditions.

[0148] According to another embodiment of this application, a near-eye optical display device is also provided, the near-eye optical display device including the optical engine lens module and the light guide device as described above, wherein the exit pupil diameter of the optical engine lens module matches the entrance pupil diameter of the light guide device.

[0149] In this embodiment of the application, a near-eye optical display device is provided. The device includes an optical engine lens module as described in any of the above embodiments, and a light guide device (such as a waveguide or prism) coupled to the optical engine lens module in the optical path.

[0150] In this design, the exit pupil of the optical-mechanical lens module and the entrance pupil of the light guide device are matched in size and position. This pupil-matching design ensures that the imaging beam output from the optical-mechanical lens module can be efficiently received and conducted by the light guide device, thereby minimizing light energy loss at the interface and suppressing stray light generation. This not only helps improve the energy utilization of the entire optical system but also ensures that the final image reaching the human eye has sufficient brightness, uniform field of view coverage, and good contrast.

[0151] The beneficial effect of this near-eye optical display device embodiment lies in its integration of the compact, wide-field-of-view, high-image-quality, and wide-temperature-stability optomechanical lens module protected by this application with the key light guide device in the near-eye display system. Through pupil matching, it not only fully retains all the performance advantages of the optomechanical lens module (such as ultra-short total optical length TTL, DFOV≥35°, high image quality in a single green band, and temperature stability), but also constructs a highly efficient, thin, and stable complete imaging optical path from the micro-MicroLED image source to the human eye. Therefore, this embodiment provides a comprehensive near-eye display device solution with high performance, high integration, and good environmental adaptability.

[0152] The specific implementation of the near-eye optical display device in this application can refer to the above-described embodiments of the optical engine lens module. Therefore, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0153] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0154] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. An optical-mechanical lens module, characterized in that, Along the optical axis from the object side to the image side, the following are included in sequence: The first lens group includes a first lens (1) with positive optical power, and the first lens (1) is a glass lens; The second lens group includes three plastic lenses, which are arranged along the optical axis as a second lens (2) with positive optical power, a third lens (3) with negative optical power, and a fourth lens (4) with negative optical power. Among them, the first lens (1) is a common lens that keeps the structural parameters fixed when adapting to MicroLED microdisplays (5) with different resolutions; The total optical length (TTL) of the optical engine lens module is 5.1mm ≤ TTL ≤ 5.6mm.

2. The optical-mechanical lens module according to claim 1, characterized in that, The refractive index Nd1 of the first lens (1) is 1.58≤Nd1≤1.6; The refractive index Nd2 of the second lens (2) is 1.6≤Nd2≤1.7; The refractive indices Nd3 and Nd4 of the third lens (3) and the fourth lens (4) satisfy: 1.65≤Nd3 and Nd4≤1.68, and Nd2 is less than Nd3 and Nd4.

3. The optical-mechanical lens module according to claim 1, characterized in that, The center thickness of the second lens (2) is T2, the center thickness of the third lens (3) is T3, and the center thickness of the fourth lens (4) is T4, and satisfies: 0.5 < (T2 + T3) / T4 < 1.

0.

4. The optical-mechanical lens module according to claim 1 or 3, characterized in that, The center thickness T1 of the first lens (1) satisfies 14.6% ≤ T1 / TTL ≤ 15.8%; The center thicknesses T2, T3, and T4 of the second lens (2), the third lens (3), and the fourth lens (4) respectively satisfy: 12.05%≤T2 / TTL≤14.8%, 5.5%≤T3 / TTL≤6.6%, and 22.94%≤T4 / TTL≤30.6%.

5. The optical-mechanical lens module according to claim 1, characterized in that, The maximum aperture of all lenses in the optical-mechanical lens module is D0, and satisfies: 0.2 < D0 / TTL < 1.

0.

6. The optical-mechanical lens module according to claim 1, characterized in that, The first lens (1), the second lens (2), the third lens (3) and the fourth lens (4) are all aspherical lenses with a conic coefficient of -20 to 20.

7. The optical-mechanical lens module according to claim 1, characterized in that, The optical-mechanical lens module meets the following conditions: The air gap between any two adjacent lenses shall not be less than 0.080 mm; The center thickness of any lens shall not be less than 0.305 mm; The distance from the image side to the image plane of the fourth lens (4) is not less than 0.5 mm.

8. The optical-mechanical lens module according to claim 1, characterized in that, The effective focal length f1 of the first lens (1) ranges from 1 mm to 5 mm; The effective focal length f2 of the second lens (2) ranges from 1 mm to 5 mm; The effective focal length f3 of the third lens (3) is in the range of -5mm to -1mm; The effective focal length f4 of the fourth lens (4) is in the range of -150mm to -100mm, -20mm to -10mm or -10mm to -1mm.

9. The optical-mechanical lens module according to claim 1, characterized in that, The effective focal length f of the optical-mechanical lens module is 4.3mm~5.0mm, and the field of view (FOV) of the optical-mechanical lens module is not less than 35° when the working wavelength is 502nm~552nm.

10. The optical-mechanical lens module according to claim 1 or 8, characterized in that, The optical-mechanical lens module also includes a MicroLED microdisplay (5) disposed at the image plane position, and the distance from the image side of the fourth lens (4) near the MicroLED microdisplay (5) to the light-emitting surface of the MicroLED microdisplay (5) is not less than 0.5mm; The MicroLED microdisplay (5) has a pixel size of 2.5μm and a resolution of 660×880, 720×960 or 780×1040.

11. A near-eye optical display device, characterized in that, include: The optical-mechanical lens module as described in any one of claims 1-10; as well as, The light guide device is provided in which the exit pupil diameter of the optical engine lens module is matched with the entrance pupil diameter of the light guide device.

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