Optical projection system and AR display device

Abstract

The embodiment of the invention provides an optical projection system and AR display equipment. The optical projection system sequentially comprises a first imaging lens group, a second imaging lens group and a third imaging lens group from an object space side to an image space side along the same optical axis. The first imaging lens group comprises a light-transmitting flat plate which is obliquely arranged; the first imaging lens group has focal power phi 2 ', the second imaging lens group has focal power phi 2', the third imaging lens group has focal power phi 3 ', and the total focal power phi of the optical projection system meets the condition that phi 2'-phi 3 ' / phi is larger than or equal to 0.01 and smaller than or equal to 2.

Description

Technical Field

[0001] Embodiments of the present application relate to the technical field of optical display systems. More specifically, embodiments of the present application relate to an optical projection system and an AR display device. Background Art

[0002] With the continuous development of near-eye display technology, users have higher and higher requirements for the imaging quality of projection devices. While traditional projection optical systems improve light efficiency, it is often difficult to effectively reduce the ghosting phenomenon, which affects the clarity of the user experience. The ghosting phenomenon is mainly caused by reflections on the lens surface. How to reduce such reflections while ensuring light efficiency has become an important challenge in the design of current projection optical systems. Summary of the Invention

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

[0004] In a first aspect, embodiments of the present application provide an optical projection system. The optical projection system sequentially includes a first imaging lens group, a second imaging lens group, and a third imaging lens group along the same optical axis from the object side to the image side; The first imaging lens group includes a light-transmitting flat plate disposed obliquely; The second imaging lens group has a focal power φ2', and the third imaging lens group has a focal power φ3'. The total focal power φ of the optical projection system satisfies: 0.01 ≤ |φ2' - φ3'| / φ ≤ 2.

[0005] Optionally, the light-transmitting flat plate forms an angle θ with the vertical direction of the optical axis, and θ ≥ 8°.

[0006] Optionally, the optical projection system further includes a display screen and a prism; The display screen is located on the image side of the optical projection system; The prism is located between the display screen and the third imaging lens group.

[0007] Optionally, the lens closest to the display screen in the second imaging lens group has a negative focal power.

[0008] Optionally, the telecentricity Tele of the optical projection system satisfies: Tele < 1°, where Tele is the exit angle of the chief ray of the optical projection system from the display screen.

[0009] Optionally, the optical projection system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens sequentially arranged along the optical axis, where: The third imaging lens group includes a first lens and a second lens; The second imaging lens group includes a third lens to a sixth lens, and the optical power of the third lens is negative.

[0010] Optionally, the optical projection system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens sequentially arranged along the optical axis, where: The third imaging lens group includes a first lens to a third lens; The second imaging lens group includes a fourth lens to a sixth lens, and the optical power of the fourth lens is negative.

[0011] Optionally, the maximum thickness T1 and the minimum thickness T2 of the first lens satisfy: 1.3 ≤ T1 / T2 ≤ 1.6.

[0012] Optionally, the optical powers of the lenses satisfy: The optical power φ1 of the first lens satisfies: 0.1 < φ1 < 0.2; The optical power φ2 of the second lens satisfies: -0.08 < φ2 < 0.05; The optical power φ3 of the third lens satisfies: -0.18 < φ3 < -0.05; The optical power φ4 of the fourth lens satisfies: -0.15 < φ4 < -0.01; The optical power φ5 of the fifth lens satisfies: -0.01 < φ5 < 0.02; The optical power φ6 of the sixth lens satisfies: 0.16 < φ6 < 0.17.

[0013] Optionally, the ratio of the maximum effective optical diameter Dmax of the lens in the optical projection system to the total optical length TTL of the optical projection system satisfies: 0.4 ≤ Dmax / TTL ≤ 0.55; where, TTL < 15 mm.

[0014] In a second aspect, an embodiment of the present application provides an AR display device, which includes: A housing; and The optical projection system as described in the first aspect.

[0015] The beneficial effects of the present application are: The optical projection system provided by the embodiment of the present application sequentially arranges a first imaging lens group, a second imaging lens group, and a third imaging lens group along the same optical axis from the object side to the image side. The first imaging lens group among them particularly uses an inclined light-transmitting flat plate. This design enables the system to reflect the ghost light formed due to the reflection on the lens surface to an area where the human eye cannot observe, thereby effectively reducing the influence of the ghost phenomenon on the clarity of the projection image.

[0016] In addition, the second imaging lens group and the third imaging lens group, through their respective specific optical power (φ2' and φ3') configurations and the relationship of 0.01 ≤ |φ2' - φ3'| / φ ≤ 2 satisfied by the total optical power φ of the system, jointly achieve a significant improvement in the overall imaging quality of the system. The second imaging lens group is responsible for correcting the geometric aberrations of the system to ensure the clarity and accuracy of the image edges. The third imaging lens group further optimizes the light distribution and utilization efficiency by controlling the emission angle, improving the overall light efficiency of the system.

[0017] In summary, the optical projection system provided by the embodiments of the present application not only effectively reduces the ghosting phenomenon, improves the clarity and contrast of the projected image, but also significantly enhances the overall imaging quality of the system through reasonable aberration correction and emission angle control. This system is not only applicable to AR display devices, providing high-quality projection display support for augmented reality technology, but also can be widely used in other occasions that require high-quality projection display, such as projectors and virtual reality devices.

[0018] Other features and advantages of the present specification will become clear through the following detailed description of the exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings incorporated in and constituting a part of this specification illustrate embodiments of the present specification and, together with the description, are used to explain the principles of the present specification.

[0020] Figure 1 One of the schematic diagrams of the optical architecture of the optical projection system provided by the embodiments of the present application; Figure 2 Another schematic diagram of the optical architecture of the optical projection system provided by the embodiments of the present application; Figure 3 is Figure 1 and Figure 2 The dot array diagram of the optical projection system shown; Figure 4 is Figure 1 and Figure 2 The MTF diagram of the optical projection system shown; Figure 5 is Figure 1 and Figure 2 The field curvature and optical distortion diagram of the optical projection system shown; Figure 6 is Figure 1 and Figure 2 The lateral chromatic aberration diagram of the optical projection system shown; Figure 7 Another schematic diagram of the optical architecture of the optical projection system provided by the embodiments of the present application; Figure 8 isFigure 7 Dot array diagram of the shown optical projection system; Figure 9 is Figure 7 MTF diagram of the shown optical projection system; Figure 10 is Figure 7 Field curvature and optical distortion diagram of the shown optical projection system; Figure 11 is Figure 7 Axial chromatic aberration diagram of the shown optical projection system; Figure 12 Figure 4 is a schematic diagram of the optical architecture of the optical projection system provided by the embodiment of the present application; Figure 13 is Figure 12 Dot array diagram of the shown optical projection system; Figure 14 is Figure 12 MTF diagram of the shown optical projection system; Figure 15 is Figure 12 Field curvature and optical distortion diagram of the shown optical projection system; Figure 16 is Figure 12 Axial chromatic aberration diagram of the shown optical projection system.

[0021] Explanation of reference numerals: 1. Display screen; 2. Prism; G1. First imaging lens group; G2. Second imaging lens group; G3. Third imaging lens group; 01. Aperture; 3. First lens; 31. First surface; 32. Second surface; 4. Second lens; 41. Third surface; 42. Fourth surface; 5. Third lens; 51. Fifth surface; 52. Sixth surface; 6. Fourth lens; 61. Seventh surface; 62. Eighth surface; 7. Fifth lens; 71. Ninth surface; 72. Tenth surface; 8. Sixth lens; 81. Eleventh surface; 82. Twelfth surface; 9. Transparent flat plate. Detailed implementation manners

[0022] Now, various exemplary embodiments of the present application will 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.

[0023] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way a limitation on the present application, its application, or its use.

[0024] Technologies and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies and devices should be regarded as part of the specification.

[0025] In all of the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments may have different values.

[0026] It should be noted that like reference numerals and letters denote like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

[0027] The optical projection system and the AR display device provided by the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0028] According to an embodiment of the present application, an optical projection system is provided. Refer to Figure 1 and Figure 2 , the optical projection system sequentially includes a first imaging lens group G1, a second imaging lens group G2, and a third imaging lens group G3 along the same optical axis from the object side to the image side; the first imaging lens group G1 includes a transmissive flat plate 9 disposed obliquely; the second imaging lens group G2 has a focal power φ2', the third imaging lens group G3 has a focal power φ3', and the total focal power φ of the optical projection system satisfies: 0.01 ≤ |φ2' - φ3'| / φ ≤ 2.

[0029] The optical projection system provided by the embodiments of the present application, with its unique optical design and excellent optical performance, demonstrates extensive application field expansibility. In particular, the system shows significant advantages in the field of AR (augmented reality) optical displays, which is conducive to providing users with a clear augmented reality visual experience. At the same time, the system also has the potential to be applied in near-eye optical display fields such as VR (virtual reality), and can bring equally excellent visual performance and user experience to these fields. The optical projection system provided by the embodiments of the present application will be described in detail below.

[0030] The optical projection system provided by the embodiments of the present application, due to its optical design features, is particularly suitable for being applied to the optical engine system of an AR (augmented reality) display device. Through the integration of this optical projection system, the AR display device can achieve high-quality and high-definition image projection, providing users with an immersive augmented reality experience.

[0031] For the optical projection system provided by the embodiments of the present application, please refer to the layout of its optical structure Figure 1 and Figure 2 as shown. The imaging lens group part of the optical projection system is arranged in sequence along the same optical axis from the object side to the image side, and is mainly composed of a first imaging lens group G1, a second imaging lens group G2, and a third imaging lens group G3. These three imaging lens groups work together to jointly achieve a high-quality optical projection effect. The following is a specific description of each lens group.

[0032] The first imaging lens group G1: This lens group is located at the position closest to the object side in the optical projection system, that is, on the side close to the aperture 01. The unique feature of its design is that it includes a transmissive flat plate 9 arranged obliquely, see Figure 1 and Figure 2 . There is an essential difference in the layout between this transmissive flat plate 9 and the lenses used in other imaging lens groups in the optical projection system. Its core advantage is that through the set tilt angle, it effectively suppresses the reflection phenomenon on the surface of the lens closest to the aperture 01 in the optical projection system. Specifically, this design can guide the reflected light rays that form ghost images to deviate from the human eye's visual range and reflect them to areas that cannot be directly observed by the human eye, thereby blocking the path of ghost image generation at the source. This design not only significantly reduces the occurrence of ghost images, but also improves the contrast of the image. By reducing the interference of unnecessary reflected light rays, the projected image can show higher clarity and color saturation, thus bringing a clearer and more vivid visual experience to the user.

[0033] The second imaging lens group G2: As a key optical correction unit in the optical projection system, it can be designed to be composed of 3 to 4 lenses in combination and has a focal power φ2'. The second imaging lens group G2 mainly realizes the efficient correction of geometric aberrations in the optical projection system. These geometric aberrations mainly include spherical aberration and coma, etc., which are inevitable imaging defects in the optical system. Their existence will significantly reduce the imaging quality, resulting in problems such as blurred images and edge distortion, thereby affecting the user's visual experience.

[0034] The second imaging lens group G2 in the present application can adopt the following design to achieve the correction of geometric aberrations: The second imaging lens group G2 includes 3 to 4 lenses, and these lenses each undertake specific light regulation tasks to ensure that the second imaging lens group G2 can correct different types of geometric aberrations.

[0035] Moreover, each lens is designed to have a specific optical power, and the distribution of these optical powers is the key to achieving geometric aberration correction. Additionally, by reasonably adjusting the optical parameters of each lens, such as the radius of curvature, thickness, and material selection, etc., the precise convergence or divergence of light can be achieved, thereby effectively offsetting or reducing the imaging deviation caused by geometric aberration.

[0036] All the lenses in the second imaging lens group G2 are designed with full consideration of the interaction and compensation relationship between various aberrations. Through reasonable optical power distribution, an aberration compensation mechanism is formed. When light passes through the second imaging lens group G2, it can correct the deviation in the light propagation path, ensuring the clarity and accuracy of the projected image.

[0037] In summary, the second imaging lens group G2 achieves the efficient correction of geometric aberration in the optical projection system through advanced means such as the collaborative action of multiple lenses, precise optical power distribution, and aberration compensation mechanism. This design not only provides users with high-quality visual output but also lays a foundation for the further development of the optical projection system in high-end application fields.

[0038] The third imaging lens group G3: This lens group can be designed to include 2 to 3 lenses and has an optical power φ3'. Its main function is to modulate the emission angle and optimize the light propagation path. By adjusting the incident and exit angles of light, the third imaging lens group G3 can effectively improve the light efficiency of the entire optical projection system, enabling more light to be effectively utilized, thereby increasing the energy utilization rate of the entire optical projection system.

[0039] Specifically, the lenses within the third imaging lens group G3 can adjust the incident and exit angles of light. This modulation effect optimizes the propagation direction of light when it passes through the third imaging lens group G3, thereby more effectively covering the projection area.

[0040] By reasonably configuring the optical power and surface shape of the lenses, the third imaging lens group G3 can guide light to propagate in a more efficient manner. This not only reduces the loss of light during propagation but also ensures that the light can be more accurately focused on the projection surface, improving the clarity and brightness of the image.

[0041] Due to the optimization effect of the third imaging lens group G3 on the light propagation path, more light can be effectively utilized. This directly increases the energy utilization rate of the entire optical projection system, reduces energy waste, and at the same time brings a brighter and clearer projection effect to users.

[0042] The third imaging lens group G3 plays a crucial role in the entire optical projection system. It not only optimizes the light propagation path but also significantly improves the light efficiency and energy utilization rate of the system, providing strong support for the high-performance performance of the entire optical projection system.

[0043] Optionally, the third imaging lens group G3 includes 2 to 3 lenses in the basic configuration, but this quantity is not fixed. According to the optical requirements in actual applications, such as the need for more precise light control, wider viewing angle coverage, or higher imaging quality, the number of lenses in the third imaging lens group G3 can be flexibly and appropriately increased.

[0044] In addition, the total optical power φ of the optical projection system provided by the embodiments of the present application satisfies the following relational expression: 0.01 ≤ |φ2' - φ3'| / φ ≤ 2. This relational expression ensures that the entire optical projection system can achieve high light energy utilization while maintaining excellent image quality by balancing the optical power difference between the second imaging lens group G2 (mainly responsible for aberration correction) and the third imaging lens group G3 (mainly responsible for light efficiency control).

[0045] Specifically, if the ratio of |φ2' - φ3'| / φ is too small (such as less than 0.01), it means that the roles of the second imaging lens group G2 and the third imaging lens group G3 in aberration correction and light efficiency modulation will be insufficient, which cannot meet the requirements of actual applications. On the contrary, if the ratio of |φ2' - φ3'| / φ is too large (such as greater than 2), it will lead to the deterioration of the image quality of the optical projection system or the decrease of light efficiency, which is also not conducive to the overall performance of the system. Therefore, the present application ensures the best balance between image quality and light efficiency by precisely controlling this ratio.

[0046] Generally speaking, the optical projection system provided by the embodiments of the present application is sequentially provided with a first imaging lens group G1, a second imaging lens group G2, and a third imaging lens group G3 along the same optical axis from the object side to the image side. The first imaging lens group G1 particularly adopts an inclined transmissive flat plate 9, and this design enables the system to reflect the ghost light formed due to the reflection on the lens surface to an area where the human eye cannot observe, thereby effectively reducing the influence of the ghost phenomenon on the clarity of the projection image.

[0047] In addition, the second imaging lens group G2 and the third imaging lens group G3 are configured with their respective specific optical powers (φ2' and φ3'), and the relationship of 0.01 ≤ |φ2' - φ3'| / φ ≤ 2 satisfied by the total optical power φ of the system together achieve a significant improvement in the overall imaging quality of the system. The second imaging lens group G2 is responsible for correcting the geometric aberrations of the system to ensure the clarity and accuracy of the image edges. The third imaging lens group G3 further optimizes the light distribution and utilization efficiency by controlling the emission angle, improving the overall light efficiency of the system.

[0048] It can be seen that the optical projection system provided by the embodiments of the present application not only effectively reduces the ghost image phenomenon, improves the clarity and contrast of the projected image, but also significantly improves the overall imaging quality of the system through reasonable aberration correction and emission angle control. This system is not only applicable to AR display devices, providing high-quality projection display support for augmented reality technology, but also can be widely used in other occasions that require high-quality projection display, such as projectors and virtual reality devices.

[0049] In some examples of the present application, the transparent flat plate 9 forms an angle θ with the vertical direction of the optical axis, and θ ≥ 8°.

[0050] In an optical projection system, the ghost image phenomenon is one of the key factors affecting imaging quality, which is mainly caused by stray light reflected from the lens surface, especially at the lens near the aperture. The reflected light is likely to form a secondary image, thereby reducing the contrast and clarity of the image. To address this problem, in this example of the present application, an optical solution for suppressing ghost images is proposed by optimizing the tilt angle of the transparent flat plate 9 relative to the vertical direction (the direction perpendicular to the optical axis), that is, the angle θ mentioned in this example.

[0051] Regarding the necessity of θ ≥ 8°: By setting the tilt angle of the transparent flat plate 9 ≥ 8°, the present application makes full use of the reflection characteristics of light on the inclined surface. Specifically, when light is incident on the inclined transparent flat plate 9 at a certain angle, its reflected light will be guided to an area that cannot be directly observed by the human eye, effectively reducing the possibility of the reflected light forming a ghost image from entering the imaging optical path.

[0052] While ensuring the ghost image suppression effect, the present application also takes into account the overall design and performance balance of the optical projection system. An excessively large angle θ (such as θ > 14°) will further reduce the ghost image, but will introduce asymmetric aberrations (such as coma and astigmatism), affecting the clarity of the edge field of view. In addition, the increase in the angle θ will also increase the distance between the imaging lens groups, resulting in an increase in the total optical length TTL of the entire optical projection system, which may affect the compactness and portability of the system.

[0053] More importantly, if the included angle θ is too large, it may also cause light loss during transmission, reducing the light efficiency of the system.

[0054] In a more preferred example, the transparent flat plate 9 forms an included angle θ with the vertical direction of the optical axis, and 8° ≤ θ ≤ 14°.

[0055] The optical design in this example of the present application effectively reduces the ghosting phenomenon. The reduction of the ghosting phenomenon directly improves the imaging quality of the projected image, making the image clearer and having a higher contrast.

[0056] The optical design in this example of the present application, by reasonably controlling the value of θ, avoids other optical performance problems introduced due to too large an inclination angle, ensuring the overall performance stability of the system.

[0057] For example, in occasions where a higher ghosting suppression effect is required, θ = 12° or 14° can be selected. While in occasions where a higher requirement for system compactness is needed, θ = 8° can be chosen.

[0058] In summary, by optimizing the inclination angle of the transparent flat plate 9, the present application not only effectively suppresses the ghosting phenomenon and significantly improves the imaging quality, but also controls the total optical length TTL (Total Track Length) of the optical projection system. This design takes into account the compactness of the system while ensuring high-quality imaging.

[0059] In some examples of the present application, referring to Figure 1 and Figure 2 , the optical projection system further includes a display screen 1 and a prism 2; wherein, the display screen 1 is located on the image side of the optical projection system; the prism 2 is located between the display screen 1 and the third imaging lens group.

[0060] The optical projection system provided by the embodiment of the present application, in addition to including the above three imaging lens groups, further includes a display screen 1 and a prism 2; wherein, the display screen 1 is placed on the image side of the optical projection system. The display screen 1 is the source of image information and is responsible for outputting the content to be projected.

[0061] The prism 2 is arranged between the display screen 1 and the third imaging lens group and plays a key role in turning and guiding light. In the present application, the prism can change the propagation direction of light, enabling the light emitted from the display screen 1 to enter the subsequent imaging lens group at an appropriate angle and path, which is crucial for optimizing the optical path design, reducing light loss, and improving the imaging quality.

[0062] Through the introduction of the prism 2, the optical projection system of the present application realizes a flexible turning of the optical path, enabling the light emitted from the display screen 1 to enter the subsequent imaging lens group more efficiently. This design not only reduces the transmission distance and loss of light, but also improves the utilization rate of light, thereby contributing to the improvement of the overall imaging efficiency.

[0063] The material of the prism 2 can be selected as high-transmission glass (such as BK7, refractive index n≈1.52) to reduce the interface reflection loss.

[0064] In some examples of the present application, referring to Figure 1 , the lens closest to the display screen 1 in the second imaging lens group G2 has a negative optical power.

[0065] In the design of this example of the present application, the lens (such as Figure 1 the third lens 5 shown in ) closest to the display screen 1 in the second imaging lens group G2 has a negative optical power. This design plays an important role in optimizing the telecentricity performance of the entire optical projection system.

[0066] When the light emitted from the display screen 1 passes through the prism 2 and the third imaging lens group G3 in sequence and then enters the second imaging lens group G2, if the first lens (i.e., the lens closest to the display screen 1) has a negative optical power (for example, its optical power value is about -0.12), the following significant effects will be produced on the chief ray: The diverging characteristic of the negative optical power lens causes the chief ray of the marginal field of view to deflect outward moderately. This effect effectively cancels the problem of the increased incident angle caused by the compact design of the system (such as TTL<15mm), ensuring that the light is in an ideal propagation state before entering the subsequent lens group.

[0067] By carefully designing the curvature radius, thickness of the negative lens and its specific position in the system, the accurate control of the exit angle of the chief ray can be achieved. Finally, the angle Tele of the chief ray exiting from the second imaging lens group G2 is strictly controlled within 1° (for the specific optical path schematic, refer to Figure 1 ), thereby significantly optimizing the telecentricity performance of the optical projection system.

[0068] The negative focal length lens (such as the third lens 5) in the second imaging lens group G2 that is close to the display screen 1 does not exist in isolation, but needs to cooperate closely with the positive focal length lenses (such as the first lens 3 and the second lens 4) in the third imaging lens group G3. This synergistic effect ensures that the overall propagation path of light in the system neither diverges excessively (resulting in a decrease in light efficiency) nor converges excessively (causing an increase in aberration). Specifically, the total optical power φ of the entire optical projection system must strictly satisfy the condition of 0.01 ≤ |φ2' - φ3'| / φ ≤ 2 to achieve the best balance between telecentricity and aberration.

[0069] In summary, by designing the lens closest to the display screen 1 in the second imaging lens group G2 to have a negative focal length and precisely controlling its divergence effect, telecentricity compensation, and synergistic effect with the third imaging lens group G3, the optical projection system of the present application achieves a significant optimization of telecentricity. This design not only improves the imaging quality of the system but also enhances its adaptability and stability under a compact design.

[0070] In some examples of the present application, the telecentricity Tele of the optical projection system satisfies: Tele < 1°, where Tele is the exit angle of the chief ray of the optical projection system from the display screen 1.

[0071] In an optical projection system, telecentricity (abbreviated as Tele) is an index that measures the parallelism between the chief ray and the optical axis, and it directly affects the quality of the projected image, specifically manifested in aspects such as brightness uniformity, color consistency, and imaging distortion.

[0072] Regarding brightness uniformity: The deviation of the chief ray angle will cause vignetting at the edge of the image, affecting the overall brightness distribution of the projected image.

[0073] Color consistency: Light emerging at a large angle is prone to chromatic aberration, making the performance of the projected image inconsistent in different color channels.

[0074] Imaging distortion: A non-telecentric system will exacerbate image distortion, causing a certain distortion in the shape of the projected image.

[0075] In order to achieve the telecentricity requirement of Tele < 1° in the optical projection system provided in the embodiments of the present application, the following key optical designs are specifically adopted in the present application: (1) The negative focal length design in the second imaging lens group G2: Design the lens closest to the display screen 1 in the second imaging lens group G2 to have a negative optical power, which can effectively diverge the marginal rays and compensate for the problem of increased incident angle caused by the compact design of the system (such as the total optical length TTL < 15 mm), thereby reducing the telecentricity Tele.

[0076] (2)Adjustment of the refraction interface of the prism 2: The prism 2 can adjust the angle of the chief ray through its refraction interface, which can further optimize the propagation path of the light rays and also helps to reduce the telecentricity Tele.

[0077] (3)Positive optical power configuration of the third imaging lens group G3: A positive optical power configuration is adopted in the third imaging lens group G3, and its converging effect makes the chief ray parallel to the optical axis, ensuring the optimization of the overall telecentricity of the system.

[0078] These key technologies cooperate with each other to jointly ensure the realization of the telecentricity Tele < 1° of the optical projection system provided by the embodiment of the present application. The optimization of the telecentricity not only improves the clarity of the projected image and reduces the aberrations (such as distortion and field curvature, etc.) caused by the inclination of the light rays, but also ensures that the projected image performs more consistently in each field of view. Whether it is the central field of view or the marginal field of view, users can obtain a better visual experience.

[0079] Specifically, when the telecentricity is small, the chief ray is more parallel to the optical axis, thereby effectively reducing various aberrations caused by the inclination of the light rays and making the projected image more delicate and real. At the same time, the small telecentricity design also enhances the brightness uniformity and color consistency of the projected image, further improving the user's satisfaction.

[0080] In summary, the present application realizes the optical optimization goal of the telecentricity Tele < 1° of the optical projection system by comprehensively applying key optical technologies such as the negative optical power design of the second imaging lens group G2, the adjustment of the refraction interface of the prism 2, and the positive optical power configuration of the third imaging lens group G3, significantly improving the quality of the projected image and the user experience.

[0081] In some examples of the present application, see Figure 1 and Figure 12 , the optical projection system includes a first lens 3, a second lens 4, a third lens 5, a fourth lens 6, a fifth lens 7, and a sixth lens 8 arranged in sequence along the optical axis, where: the third imaging lens group G3 includes the first lens 3 and the second lens 4; the second imaging lens group G2 includes the third lens 5 to the sixth lens 8, and the optical power of the third lens 5 is negative.

[0082] The optical projection system provided by the embodiments of the present application has its imaging part configured with a second imaging lens group G2 and a third imaging lens group G3. These two imaging lens groups cooperate together to ensure the high-performance performance of the system. Specifically, a total of six lenses are included in these two imaging lens groups, which are respectively: the first lens 3, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, and the sixth lens 8. The combination of these six lenses is designed to achieve high definition, low distortion, and excellent color restoration ability of the optical projection system, thus bringing an excellent visual experience to users.

[0083] See Figure 1 and Figure 12 , the third imaging lens group G3 is designed to be composed of the first lens 3 and the second lens 4; the second imaging lens group G2 is composed of the third lens 5 to the sixth lens 8.

[0084] It should be noted that the third lens 5 is the closest to the display screen 1 in the second imaging lens group G2, and its optical power is designed to be negative. In this grouping case, the negative optical power design of the third lens 5 helps to diverge the marginal rays, compensates for the problem of increased incident angle that may be brought about by the compact design of the system (such as TTL < 15mm), thereby reducing the telecentricity and improving the brightness uniformity and color consistency of the projected image.

[0085] The third imaging lens group G3 is mainly responsible for the modulation of the emission angle to improve the light efficiency of the entire optical projection system; while the second imaging lens group G2 focuses on the correction of geometric aberrations to improve the image quality. The collaborative work of these two imaging lens groups ensures the optimization of the overall performance of the optical system.

[0086] By precisely controlling the optical power and arrangement of each lens, this example of the present application achieves the optimization goal of a telecentricity Tele < 1°, reduces the aberrations generated due to the inclination of the light rays, and improves the clarity and consistency of the projected image.

[0087] In some examples of the present application, see Figure 7 , the optical projection system includes the first lens 3, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, and the sixth lens 8 arranged in sequence along the optical axis, where: the third imaging lens group G3 includes the first lens 3 to the third lens 5; the second imaging lens group G2 includes the fourth lens 6 to the sixth lens 8, and the optical power of the fourth lens 6 is negative.

[0088] The optical projection system provided by the embodiments of the present application has its imaging part configured with a second imaging lens group G2 and a third imaging lens group G3. These two imaging lens groups cooperate together to ensure the high-performance performance of the system. Specifically, a total of six lenses are included in these two imaging lens groups, which are respectively: the first lens 3, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, and the sixth lens 8. The combination of these six lenses aims to achieve high definition, low distortion, and excellent color reproduction ability of the optical projection system, thereby bringing an excellent visual experience to users.

[0089] See Figure 7 , in this example of the present application, the division of the second imaging lens group G2 and the third imaging lens group G3 is as follows: the third imaging lens group G3 is composed of the first lens 3 to the third lens 5; the second imaging lens group G2 is composed of the fourth lens 6 to the sixth lens 8. It should be noted that the fourth lens 6, which is the closest to the display screen 1 in the second imaging lens group G2, has its optical power designed to be negative. This design also plays a role in diverging the marginal rays and reducing the telecentricity.

[0090] Compared with Figure 1 and Figure 12 the example shown, Figure 7 in the example, the third imaging lens group G3 in the example undertakes more tasks of luminous angle modulation and light efficiency improvement because it includes more lenses (i.e., the first lens 3 to the third lens 5). And the second imaging lens group G2 is still used for correcting geometric aberrations. This functional division and adjustment make the optical projection system more balanced and optimized in terms of overall performance.

[0091] Although in Figure 7 the example, the position of the negative optical power lens has changed compared with other examples (i.e., from the third lens 5 to the fourth lens 6), the present application still achieves the optimization goal of telecentricity Tele < 1° by precisely controlling the optical power and arrangement of each lens. At the same time, through reasonable aberration correction measures, it ensures that the clarity and consistency of the projected image are not affected.

[0092] In summary, the above two examples ( Figure 1 and Figure 12 the example and Figure 7 the example) show how the optical projection system realizes the optimization of telecentricity and the improvement of overall performance under different imaging lens group divisions and specific lens optical power configurations. By precisely controlling the optical power and arrangement of each lens, and reasonably dividing the functions of the imaging lens groups, the telecentricity can be effectively reduced, the aberration can be reduced, and the clarity and consistency of the projected image can be significantly improved.

[0093] In some examples of the present application, see Figure 1 andFigure 2 The maximum thickness T1 and the minimum thickness T2 of the first lens 3 satisfy: 1.3 ≤ T1 / T2 ≤ 1.6.

[0094] First, from the perspective of optimizing optical performance, by precisely controlling the thickness ratio of different regions (especially the central region and the edge region) of the first lens 3, spherical aberration and coma in the optical projection system can be significantly reduced. This is because the shape of the lens and its thickness distribution have a direct impact on the propagation path and focusing characteristics of light. When the ratio of T1 / T2 is maintained within the range of 1.3 to 1.6, the first lens 3 can more effectively guide light, reduce the deviation of light during propagation, and thus significantly improve the imaging quality.

[0095] Secondly, on the premise of ensuring optical performance, restricting the thickness ratio of different regions of the first lens 3 also helps to miniaturize the optical projection system. The first lens 3, as the lens with the largest volume and the thickest thickness in the system, has a great influence on the overall volume of the system. By optimizing its thickness ratio, the volume of the lens can be effectively reduced without sacrificing the imaging quality, thereby reducing the size and weight of the entire optical projection system. In summary, the design of the thickness ratio of the first lens 3 in this example of the present application fully reflects the pursuit of the balance between optical performance and system compactness. On the one hand, spherical aberration is reduced by optimizing the lens shape to improve the imaging quality; on the other hand, system miniaturization is achieved by controlling the lens size. This balanced design enables the optical projection system to meet high-performance requirements while better adapting to the diverse application scenario needs, demonstrating excellent practicality and adaptability.

[0096] In some examples of the present application, the optical powers of the lenses satisfy: The optical power φ1 of the first lens 3 satisfies: 0.1 < φ1 < 0.2; The optical power φ2 of the second lens 4 satisfies: -0.08 < φ2 < 0.05; The optical power φ3 of the third lens 5 satisfies: -0.18 < φ3 < -0.05; The optical power φ4 of the fourth lens 6 satisfies: -0.15 < φ4 < -0.01; The optical power φ5 of the fifth lens 7 satisfies: -0.01 < φ5 < 0.02; The optical power φ6 of the sixth lens 8 satisfies: 0.16 < φ6 < 0.17.

[0097] The optical power design adopted in the present application can achieve: aberration correction (spherical aberration, field curvature, chromatic aberration), maximizing light efficiency, and controlling telecentricity (Tele < 1°).

[0098] Specifically, for the first lens 3, its optical power range is 0.1 < φ1 < 0.2. It is the main converging lens in the entire optical path, playing a major role in enhancing the optical efficiency. It can also compensate for the astigmatism introduced by the prism.

[0099] For the second lens 4, its optical power range is -0.08 < φ2 < 0.05. The optical power of the second lens 4 can be positive or negative, and is specifically selected within the above range according to needs. The second lens 4 can be used to balance the optical powers of the first lens 3 and the third lens 5, and the design of the optical power of the second lens 4 can also suppress distortion.

[0100] For the third lens 5, its optical power range is -0.18 < φ3 < -0.05. It is a negative lens and can be used to control the telecentricity of the system. The design of the optical power of the third lens 5, combined with its high refractive index design, can offset the field curvature and significantly reduce the telecentricity of the system.

[0101] For the fourth lens 6, its optical power range is -0.15 < φ4 < -0.01. It is a negative lens and can also be used to control the telecentricity of the system, and at the same time can achieve the correction of aberrations.

[0102] For the fifth lens 7, its optical power range is -0.01 < φ5 < 0.02. In cooperation with the fourth lens 6 or the subsequent sixth lens 8, it can achieve aberration correction.

[0103] For the sixth lens 8, its optical power range is 0.16 < φ6 < 0.17. The sixth lens 8 is used to control the imaging position, and at the same time can be combined with other lenses to control the lateral chromatic aberration.

[0104] Among them, the ratio of the optical powers of the third lens 5 and the sixth lens 8 satisfies 0.3 < |φ3 / φ6| < 1.1. This can avoid the image plane bending caused by a strong negative lens.

[0105] Among them, the ratio of the optical powers of the first lens 3 and the fourth lens 6 satisfies |φ1 / φ4| > 0.67. This can ensure that the main converging ability is not overly offset.

[0106] In some examples of this application, the ratio of the maximum effective optical diameter Dmax of the lens in the optical projection system to the total optical length TTL of the optical projection system satisfies: 0.4 ≤ Dmax / TTL ≤ 0.55; where TTL < 15 mm.

[0107] In this example of the present application, by controlling the ratio range of Dmax / TTL, it is possible to ensure sufficient optical effective diameter to collect light, improve imaging brightness and contrast, while avoiding the increase in system weight and cost caused by too large a lens diameter. A reasonable Dmax / TTL ratio helps to optimize the light propagation path, reduce light loss at the lens edge, and thus improve the overall light efficiency.

[0108] The optical projection system provided by the embodiment of the present application has an optical total length TTL less than 15 mm, which directly promotes the miniaturization of the optical projection system. Combining the ratio range of Dmax / TTL can ensure that the overall size of the system is effectively controlled while maintaining optical performance. This compact design makes the optical projection system more suitable for more application scenarios with limited space.

[0109] The optical path of the optical projection system provided by the embodiment of the present application (see Figure 1 ) is as follows: Starting from the image side, the light first emits from the display screen 1, and then this light enters and passes through the prism 2 for preliminary optical path turning or adjustment. Then, the light sequentially passes through three carefully arranged imaging lens groups, namely the first lens 3, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, the sixth lens 8, and the transparent flat plate 9. Each optical lens undertakes specific optical functions, such as focusing, correcting aberrations, etc., and works together to ensure the accurate transmission of light and imaging quality. Finally, the processed light exits from the transparent flat plate 9 and accurately reaches the aperture 01. The plane where the aperture 01 is located serves as an important control interface of the optical path here, further restricting or adjusting the light. After that, the optical projection system can also externally connect other optical elements according to actual needs to expand its functions or adapt to different application scenarios.

[0110] The optical projection system design provided by the embodiment of the present application includes six lenses: the first lens 3 to the sixth lens 8. The refractive index n and dispersion coefficient v of these six lenses range from: 1.4 < n < 2.0, 20 < v < 75.

[0111] In an example, see Figure 1 and Figure 12 , the refractive index n of the first lens 3 is 1.54 and the dispersion coefficient v is 56.3; the refractive index n of the second lens 4 is 1.54 and the dispersion coefficient v is 56.3; the refractive index n of the third lens 5 is 1.65 and the dispersion coefficient v is 23; the refractive index n of the fourth lens 6 is 1.65 and the dispersion coefficient v is 23; the refractive index n of the fifth lens 7 is 1.54 and the dispersion coefficient v is 56.3; the refractive index n of the sixth lens 8 is 1.78 and the dispersion coefficient v is 47.

[0112] In an example, seeFigure 7 The refractive index n of the first lens 3 is 1.54 and the dispersion coefficient v is 56.3; the refractive index n of the second lens 4 is 1.54 and the dispersion coefficient v is 56.3; the refractive index n of the third lens 5 is 1.65 and the dispersion coefficient v is 23; the refractive index n of the fourth lens 6 is 1.65 and the dispersion coefficient v is 23; the refractive index n of the fifth lens 7 is 1.54 and the dispersion coefficient v is 56.3; the refractive index n of the sixth lens 8 is 1.8 and the dispersion coefficient v is 47.

[0113] The surfaces of the lenses in the optical projection system may be aspherical or spherical, and there is an anti-reflection film layer on the surface.

[0114] The optical projection system of the present application will be described below through Examples 1 to 3 respectively.

[0115] Example 1 The optical projection system provided in this Example 1 is shown in Figure 1 and Figure 2 and includes, in order from the object side to the image side along the same optical axis, a first imaging lens group G1, a second imaging lens group G2, a third imaging lens group G3, a prism 2, and a display screen 1; The first imaging lens group G1 includes a light-transmitting flat plate 9 disposed obliquely, and the light-transmitting flat plate 9 forms an angle θ with the vertical direction of the optical axis, and θ is 8°; The third imaging lens group G3 includes a first lens 3 and a second lens 4; The second imaging lens group G2 includes a third lens 5 to a sixth lens 8, and the optical power of the third lens 5 is negative; among them, the optical power of the third lens 5 is negative; The optical power φ1 of the first lens 3 is 0.148; The optical power φ2 of the second lens 4 is -0.037; The optical power φ3 of the third lens 5 is -0.171; The optical power φ4 of the fourth lens 6 is -0.033; The optical power φ5 of the fifth lens 7 is 0.001; The optical power φ6 of the sixth lens 8 is 0.162.

[0116] The optical parameters of the optical projection system provided in this Example 1 are shown in Table 1 below.

[0117] Table 1

[0118] The optical projection system provided in this Example 1 has optical performance as Figures 3 to 6 shown: Figure 3 is a spot diagram schematic diagram,Figure 4 is the MTF curve graph, Figure 5 is the field curvature and distortion graph, Figure 6 is the lateral chromatic aberration graph.

[0119] The spot diagram refers to a dispersion pattern formed by a large number of rays emitted from a point after passing through an optical projection system. Due to aberration, the intersection points of these rays with the image plane are no longer concentrated at the same point but are scattered within a certain range, and it is used to evaluate the imaging quality of the projection optical projection system. See Figure 3 , for the optical projection system provided in Embodiment 1 of the present invention, the maximum value of the image points in the spot diagram is less than 2 μm.

[0120] The MTF curve graph is a modulation transfer function graph, which characterizes the imaging clarity of the optical projection system through the contrast of black and white line pairs. See Figure 4 , for the optical projection system provided in Embodiment 1 of the present invention, the MTF is > 0.4 at 125 lp / mm.

[0121] See Figure 5 , for the optical projection system provided in Embodiment 1 of the present invention, the maximum distortion occurs at 1 field of view, and its absolute value is less than 1%.

[0122] Lateral chromatic aberration is also called magnification chromatic aberration. It mainly refers to the difference in the focal positions of blue light and red light on the image plane when a single principal ray of polychromatic light on the object side becomes multiple rays after passing through a refraction system due to dispersion. See Figure 6 , for the optical projection system provided in Embodiment 1 of the present invention, its maximum chromatic aberration value is less than 4 μm.

[0123] Embodiment 2 The optical projection system provided in Embodiment 2 of the present invention, see Figure 7 , which sequentially includes a first imaging lens group G1, a second imaging lens group G2, a third imaging lens group G3, a prism 2, and a display screen 1 along the same optical axis from the object side to the image side; The first imaging lens group G1 includes a light-transmitting flat plate 9 arranged obliquely, and the light-transmitting flat plate 9 forms an angle θ with the vertical direction of the optical axis, and θ is 8°; The third imaging lens group G3 includes a first lens 3 to a third lens 5; The second imaging lens group G2 includes a fourth lens 6 to a sixth lens 8, and the optical power of the third lens 5 is negative; among them, the optical power of the fourth lens 6 is negative; The optical power φ1 of the first lens 3 is 0.103; The optical power φ2 of the second lens 4 is 0.048; The optical power φ3 of the third lens 5 is -0.115; The optical power φ4 of the fourth lens 6 is -0.104; The optical power φ5 of the fifth lens 7 is -0.006; The optical power φ6 of the sixth lens 8 is 0.169.

[0124] The optical parameters of the optical projection system provided in Embodiment 2 are shown in Table 2 below.

[0125] Table 2

[0126] The optical projection system provided in Embodiment 2 has optical performance as Figures 8 to 11 shown: Figure 8 is a spot diagram schematic, Figure 9 is an MTF curve graph, Figure 10 is a field curvature and distortion graph, Figure 11 is a lateral chromatic aberration graph.

[0127] See Figure 8 , for the optical projection system provided in Embodiment 2, the maximum value of the image points in the spot diagram is less than 2 μm.

[0128] See Figure 9 , for the optical projection system provided in Embodiment 2, the MTF is > 0.4 at 125 lp / mm.

[0129] See Figure 10 , for the optical projection system provided in Embodiment 2, the maximum distortion occurs at 1 field of view, and the absolute value is less than 1%.

[0130] See Figure 11 , for the optical projection system provided in Embodiment 2, the maximum chromatic aberration value is less than 4 μm.

[0131] Embodiment 3 The optical projection system provided in Embodiment 3, see Figure 12 , includes, in order from the object side to the image side along the same optical axis, a first imaging lens group G1, a second imaging lens group G2, a third imaging lens group G3, a prism 2, and a display screen 1; The first imaging lens group G1 includes a transmissive flat plate 9 disposed obliquely, and the transmissive flat plate 9 forms an angle θ with the vertical direction of the optical axis, and θ is 8°; The third imaging lens group G3 includes a first lens 3 and a second lens 4; The second imaging lens group G2 includes a third lens 5 to a sixth lens 8, and the optical power of the third lens 5 is negative; among them, the optical power of the third lens 5 is negative; The optical power φ1 of the first lens 3 is 0.192; The optical power φ2 of the second lens 4 is -0.078; The optical power φ3 of the third lens 5 is -0.080; The optical power φ4 of the fourth lens 6 is -0.140; The optical power φ5 of the fifth lens 7 is 0.019; The optical power φ6 of the sixth lens 8 is 0.160.

[0132] The optical parameters of the optical projection system provided in Embodiment 3 are shown in Table 3 below.

[0133] Table 3

[0134] For the optical projection system provided in Embodiment 3, the optical performance is as Figures 13 to 16 shown: Figure 13 is the spot diagram schematic diagram, Figure 14 is the MTF curve graph, Figure 15 is the field curvature and distortion graph, Figure 16 is the lateral chromatic aberration graph.

[0135] Refer to Figure 13 , for the optical projection system provided in Embodiment 3, the maximum value of the image points in the spot diagram is less than 2 μm.

[0136] Refer to Figure 14 , for the optical projection system provided in Embodiment 3, the MTF is > 0.4 at 125 lp / mm.

[0137] Refer to Figure 15 , for the optical projection system provided in Embodiment 3, the maximum distortion occurs at the 1° field of view, and the absolute value is less than 1%.

[0138] Refer to Figure 16 , for the optical projection system provided in Embodiment 3, the maximum chromatic aberration value is less than 4 μm.

[0139] According to another embodiment of the present application, an AR display device is provided. The AR display device includes a housing and the optical projection system as described above. The optical projection system is disposed in the housing.

[0140] The AR display device provided in the embodiments of the present application is, for example, a VR head-mounted display device.

[0141] The specific implementation manners of the AR display device in the embodiments of the present application may refer to the respective embodiments of the above optical projection system. Therefore, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated herein one by one.

[0142] What is mainly described in the above embodiments is 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 more optimal embodiment. Considering the simplicity of the text, it will not be elaborated herein.

[0143] Although some specific embodiments of the present 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 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 projection system, characterized in that, It sequentially includes a first imaging lens group (G1), a second imaging lens group (G2), and a third imaging lens group (G3) from the object side to the image side along the same optical axis; The first imaging lens group (G1) includes a light-transmitting flat plate (9) arranged obliquely; The second imaging lens group (G2) has a focal power φ2', the third imaging lens group (G3) has a focal power φ3', and the total focal power φ of the optical projection system satisfies: 0.01 ≤ |φ2' - φ3'| / φ ≤ 2.

2. The optical projection system according to claim 1, wherein The light-transmitting flat plate (9) forms an angle θ with the vertical direction of the optical axis, and θ ≥ 8°.

3. The optical projection system according to claim 1 or 2, characterized in that, The optical projection system further includes a display screen (1) and a prism (2); The display screen (1) is located on the image side of the optical projection system; The prism (2) is located between the display screen (1) and the third imaging lens group.

4. The optical projection system according to claim 3, characterized in that, The lens closest to the display screen (1) in the second imaging lens group (G2) has a negative focal power.

5. The optical projection system according to claim 4, characterized in that, The telecentricity Tele of the optical projection system satisfies: Tele < 1°, where Tele is the exit angle of the chief ray of the optical projection system from the display screen (1).

6. The optical projection system according to claim 4, wherein The optical projection system includes a first lens (3), a second lens (4), a third lens (5), a fourth lens (6), a fifth lens (7), and a sixth lens (8) arranged in sequence along the optical axis, where: The third imaging lens group (G3) includes the first lens (3) and the second lens (4); The second imaging lens group (G2) includes the third lens (5) to the sixth lens (8), and the focal power of the third lens (5) is negative.

7. The optical projection system according to claim 4, wherein The optical projection system includes a first lens (3), a second lens (4), a third lens (5), a fourth lens (6), a fifth lens (7), and a sixth lens (8) arranged in sequence along the optical axis, where: The third imaging lens group (G3) includes the first lens (3) to the third lens (5); The second imaging lens group (G2) includes the fourth lens (6) to the sixth lens (8), and the focal power of the fourth lens (6) is negative.

8. The optical projection system according to claim 6 or 7, characterized in that, The maximum thickness T1 and the minimum thickness T2 of the first lens (3) satisfy: 1.3 ≤ T1 / T2 ≤ 1.

6.

9. The optical projection system according to claim 8, wherein, The focal powers of the respective lenses satisfy: The focal power φ1 of the first lens (3) satisfies: 0.1 < φ1 < 0.2; The focal power φ2 of the second lens (4) satisfies: -0.08 < φ2 < 0.05; The focal power φ3 of the third lens (5) satisfies: -0.18 < φ3 < -0.05; The focal power φ4 of the fourth lens (6) satisfies: -0.15 < φ4 < -0.01; The focal power φ5 of the fifth lens (7) satisfies: -0.01 < φ5 < 0.02; The focal power φ6 of the sixth lens (8) satisfies: 0.16 < φ6 < 0.

17.

10. The optical projection system according to claim 8, characterized in that, The ratio of the maximum effective optical diameter Dmax of the lens in the optical projection system to the optical total length TTL of the optical projection system satisfies: 0.4 ≤ Dmax / TTL ≤ 0.55; where TTL < 15 mm.

11. An AR display device, characterized in that, It includes: A housing; And The optical projection system according to any one of claims 1 - 10.

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