Optical projection system and AR display device

Abstract

An embodiment of the present application provides an optical projection system and an AR display device; wherein the optical projection system includes a first imaging lens group, a second imaging lens group, and a third imaging lens group, sequentially along the same optical axis from the object side to the image side; the first imaging lens group includes an inclined light-transmitting flat plate; the second imaging lens group has an optical focal length φ2', the third imaging lens group has an optical focal length φ3', and the total optical focal length φ of the optical projection system satisfies the following: 0.01≤|φ2'-φ3'| / φ≤2.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of optical display systems. More specifically, the 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 are demanding increasingly higher image quality from projection equipment. While traditional projection optical systems improve light efficiency, they often struggle to effectively reduce ghosting, which impacts user experience clarity. Ghosting is primarily caused by reflections from the lens surface. Reducing these reflections while maintaining light efficiency has become a major challenge in current projection optical system design. Summary of the Invention

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

[0004] In a first aspect, an embodiment of the present application provides an optical projection system, wherein the optical projection system includes a first imaging lens group, a second imaging lens group, and a third imaging lens group in sequence from the object side to the image side along the same optical axis;

[0005] The first imaging lens group includes a light-transmitting flat plate arranged obliquely;

[0006] The second imaging lens group has an optical power φ2', the third imaging lens group has an optical power φ3', and the total optical power φ of the optical projection system satisfies: 0.01≤|φ2'-φ3'| / φ≤2.

[0007] Optionally, the light-transmitting flat plate forms an angle θ with a direction perpendicular to the optical axis, and θ is ≥ 8°.

[0008] Optionally, the optical projection system further includes a display screen and a prism;

[0009] The display screen is located on the image side of the optical projection system;

[0010] The prism is located between the display screen and the third imaging lens group.

[0011] Optionally, the lens closest to the display screen in the second imaging lens group has negative optical power.

[0012] Optionally, the telecentricity Tele of the optical projection system satisfies: Tele<1°, where Tele is an emission angle of a main light of the optical projection system from the display screen.

[0013] 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, wherein:

[0014] The third imaging lens group includes a first lens and a second lens;

[0015] The second imaging lens group includes a third lens to a sixth lens, and the optical power of the third lens is negative.

[0016] 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, wherein:

[0017] The third imaging lens group includes first to third lenses;

[0018] The second imaging lens group includes fourth to sixth lenses, and the optical power of the fourth lens is negative.

[0019] Optionally, a maximum thickness T1 and a minimum thickness T2 of the first lens satisfy: 1.3≤T1 / T2≤1.6.

[0020] Optionally, the optical power of each lens satisfies:

[0021] The optical power φ1 of the first lens satisfies: 0.1<φ1<0.2;

[0022] The optical power φ2 of the second lens satisfies: -0.08<φ2<0.05;

[0023] The refractive power φ3 of the third lens satisfies: -0.18<φ3<-0.05;

[0024] The refractive power φ4 of the fourth lens satisfies: -0.15<φ4<-0.01;

[0025] The refractive power φ5 of the fifth lens satisfies: -0.01<φ5<0.02;

[0026] The optical power φ6 of the sixth lens satisfies the following: 0.16<φ6<0.17.

[0027] Optionally, a ratio of a maximum effective optical diameter Dmax of a lens in the optical projection system to a total optical length TTL of the optical projection system satisfies: 0.4≤Dmax / TTL≤0.55; wherein TTL<15 mm.

[0028] In a second aspect, an embodiment of the present application provides an AR display device, the AR display device comprising:

[0029] casing; and

[0030] The optical projection system as described in the first aspect.

[0031] The beneficial effects of this application are:

[0032] The optical projection system provided in an embodiment of the present application is configured with a first imaging lens group, a second imaging lens group, and a third imaging lens group in sequence along the same optical axis from the object side to the image side. The first imaging lens group specifically uses an inclined light-transmitting flat plate. This design enables the system to reflect ghost light formed by reflection from the lens surface to an area that is unobservable to the human eye, thereby effectively reducing the impact of ghosting on the clarity of the projected image.

[0033] Furthermore, the second and third imaging lens groups, through their respective specific optical power configurations (φ2' and φ3'), and the fact that the total optical power φ of the system satisfies the relationship 0.01≤|φ2'-φ3'| / φ≤2, significantly enhance the overall imaging quality of the system. The second imaging lens group corrects the system's geometric aberrations, ensuring sharpness and accuracy of image edges. The third imaging lens group further optimizes light distribution and utilization efficiency by controlling the beam angle, enhancing the overall light efficiency of the system.

[0034] In summary, the optical projection system provided by the embodiments of the present application not only effectively reduces ghosting and 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 luminous angle control. This system is not only suitable for AR display devices, providing high-quality projection display support for augmented reality technology, but can also be widely used in other occasions requiring high-quality projection display, such as projectors and virtual reality devices.

[0035] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0037] Figure 1 This is one of the optical architecture diagrams of the optical projection system provided in an embodiment of the present application;

[0038] Figure 2 The second optical architecture diagram of the optical projection system provided in an embodiment of the present application;

[0039] Figure 3 for Figure 1 and Figure 2 A dot array diagram of the optical projection system is shown;

[0040] Figure 4 for Figure 1 and Figure 2MTF diagram of the optical projection system shown;

[0041] Figure 5 for Figure 1 and Figure 2 The field curvature and optical distortion diagram of the optical projection system shown;

[0042] Figure 6 for Figure 1 and Figure 2 A diagram of vertical chromatic aberration of the optical projection system shown;

[0043] Figure 7 This is a third schematic diagram of the optical architecture of the optical projection system provided in an embodiment of the present application;

[0044] Figure 8 for Figure 7 A dot array diagram of the optical projection system is shown;

[0045] Figure 9 for Figure 7 MTF diagram of the optical projection system shown;

[0046] Figure 10 for Figure 7 The field curvature and optical distortion diagram of the optical projection system shown;

[0047] Figure 11 for Figure 7 A diagram of vertical chromatic aberration of the optical projection system shown;

[0048] Figure 12 This is a fourth schematic diagram of the optical architecture of the optical projection system provided in an embodiment of the present application;

[0049] Figure 13 for Figure 12 A dot array diagram of the optical projection system is shown;

[0050] Figure 14 for Figure 12 MTF diagram of the optical projection system shown;

[0051] Figure 15 for Figure 12 The field curvature and optical distortion diagram of the optical projection system shown;

[0052] Figure 16 for Figure 12 The vertical axis chromatic aberration diagram of the optical projection system is shown.

[0053] Description of reference numerals:

[0054] 1. Display screen; 2. Prism; G1, first imaging lens group; G2, second imaging lens group; G3, third imaging lens group; 01, aperture;

[0055] 3. First lens; 31. First surface; 32. Second surface;

[0056] 4. Second lens; 41. Third surface; 42. Fourth surface;

[0057] 5. Third lens; 51. Fifth surface; 52. Sixth surface;

[0058] 6. Fourth lens; 61. Seventh surface; 62. Eighth surface;

[0059] 7. Fifth lens; 71. Ninth surface; 72. Tenth surface;

[0060] 8. Sixth lens; 81. Eleventh surface; 82. Twelfth surface;

[0061] 9. Translucent flat plate. DETAILED DESCRIPTION

[0062] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0063] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0064] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0065] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0066] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0067] The optical projection system and AR display device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0068] According to one embodiment of the present application, an optical projection system is provided. Figure 1 and Figure 2The optical projection system 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 an inclined light-transmitting flat plate 9. The second imaging lens group G2 has an optical focal length φ2', and the third imaging lens group G3 has an optical focal length φ3'. The total optical focal length φ of the optical projection system satisfies the following: 0.01≤|φ2'-φ3'| / φ≤2.

[0069] The optical projection system provided in the embodiment of the present application, with its unique optical design and excellent optical performance, has demonstrated a wide range of application field scalability. In particular, the system has shown significant advantages in the field of AR (augmented reality) optical display, which is conducive to providing users with a clear augmented reality visual experience. At the same time, the system also has the potential for application 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 in the embodiment of the present application is described in detail below.

[0070] The optical projection system provided in the embodiments of this application, with its optical design features, is particularly suitable for use in the optical-mechanical systems of AR (augmented reality) display devices. Through the integration of this optical projection system, AR display devices can achieve high-quality, high-definition image projection, providing users with an immersive augmented reality experience.

[0071] The optical projection system provided in the embodiment of the present application, the layout of the optical structure of which can be found in Figure 1 and Figure 2 As shown in the figure, the imaging lens groups of this optical projection system are arranged sequentially along the same optical axis from the object side to the image side, and primarily comprise the first imaging lens group G1, the second imaging lens group G2, and the third imaging lens group G3. These three imaging lens groups work together to achieve high-quality optical projection effects. The following is a detailed description of each lens group.

[0072] First imaging lens group G1: This lens group is located in the optical projection system closest to the object side, that is, the side close to the aperture 01. The unique feature of its design is that it contains a tilted light-transmitting plate 9, see Figure 1 and Figure 2This light-transmitting plate 9 differs fundamentally from the lenses used in other imaging lens assemblies in the optical projection system in terms of layout. Its core advantage lies in its set tilt angle, which effectively suppresses reflections from the lens surface closest to the aperture 01 in the optical projection system. Specifically, this design guides the reflected light that causes ghosting away from the human eye's visual range, reflecting it to an area that is inaccessible to the human eye, thereby blocking the path of ghosting at its source. This design not only significantly reduces the occurrence of ghosting but also improves image contrast. By reducing the interference of unnecessary reflected light, the projected image exhibits higher clarity and color saturation, providing users with a clearer and more realistic visual experience.

[0073] Second imaging lens group G2: This lens group, a key optical correction unit in the optical projection system, can be designed to consist of three to four lenses with an optical power of φ2'. The second imaging lens group G2 primarily provides efficient correction of geometric aberrations in the optical projection system. These aberrations, including spherical aberration and coma, are unavoidable imaging defects in optical systems. Their presence significantly degrades image quality, leading to image blur and edge distortion, which in turn impacts the user's visual experience.

[0074] The second imaging lens group G2 in this application can adopt the following design to achieve correction of geometric aberrations:

[0075] The second imaging lens group G2 includes 3 to 4 lenses, each of which is responsible for a specific light regulation task, ensuring that the second imaging lens group G2 can correct different types of geometric aberrations.

[0076] Furthermore, each lens is designed with a specific optical power, and the distribution of these powers is key to achieving geometric aberration correction. Furthermore, by properly adjusting the optical parameters of each lens, such as radius of curvature, thickness, and material selection, we can achieve precise convergence or divergence of light, effectively offsetting or reducing imaging deviations caused by geometric aberrations.

[0077] The design of all lenses in the second imaging lens group G2 fully considers the interaction and compensation relationships between various aberrations. Through the rational distribution of optical power, an aberration compensation mechanism is formed. When light passes through the second imaging lens group G2, deviations in the light propagation path are corrected, ensuring the clarity and accuracy of the projected image.

[0078] In summary, the second imaging lens group G2 achieves efficient correction of geometric aberrations in optical projection systems through advanced methods such as multi-lens synergy, precise optical power distribution, and aberration compensation. This design not only provides users with high-quality visual output but also lays the foundation for the further development of optical projection systems in high-end applications.

[0079] The third imaging lens group G3 can be designed to include two to three lenses with an optical power of φ3'. Its primary function is to modulate the light beam angle and optimize the light propagation path. By adjusting the incident and exiting angles of light, the third imaging lens group G3 effectively improves the optical projection system's overall light efficiency, allowing more light to be effectively utilized, thereby increasing the system's energy efficiency.

[0080] Specifically, the lenses within the third imaging lens group G3 can adjust the incident and exit angles of light. This modulation optimizes the propagation direction of light as it passes through the third imaging lens group G3, thereby more effectively covering the projection area.

[0081] By properly configuring the focal length and surface shape of the lenses, the third imaging lens group G3 can guide light to propagate more efficiently. This not only reduces light loss during propagation, but also ensures that light is more accurately focused on the projection surface, improving the clarity and brightness of the image.

[0082] Due to the optimization of the light propagation path by the third imaging lens group G3, more light can be effectively utilized, which directly improves the energy utilization of the entire optical projection system, reduces energy waste, and also provides users with brighter and clearer projection effects.

[0083] 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 system's light efficiency and energy utilization, providing strong support for the high performance of the entire optical projection system.

[0084] Optionally, the third imaging lens group G3 includes two to three lenses in its basic configuration, but this number is not fixed. The number of lenses in the third imaging lens group G3 can be flexibly and appropriately increased based on actual optical requirements, such as those requiring finer light control, wider viewing angle coverage, or higher imaging quality.

[0085] Furthermore, the total optical power φ of the optical projection system provided in the embodiments of the present application satisfies the following relationship: 0.01 ≤ |φ2' - φ3'| / φ ≤ 2. This relationship balances the difference in optical power between the second imaging lens group G2 (primarily responsible for aberration correction) and the third imaging lens group G3 (primarily responsible for light efficiency control), ensuring that the entire optical projection system achieves efficient light energy utilization while maintaining excellent image quality.

[0086] Specifically, if the ratio |φ2'-φ3'| / φ is too small (e.g., less than 0.01), the second imaging lens group G2 and the third imaging lens group G3 will be insufficient in terms of aberration correction and light efficiency modulation, which will not meet the needs of practical applications. Conversely, if the ratio |φ2'-φ3'| / φ is too large (e.g., greater than 2), the image quality of the optical projection system will deteriorate or the light efficiency will decrease, which is also detrimental to the overall performance of the system. Therefore, by precisely controlling this ratio, the present application ensures that the optical projection system achieves an optimal balance between image quality and light efficiency.

[0087] In general, the optical projection system provided in the embodiments of the present application is configured with a first imaging lens group G1, a second imaging lens group G2, and a third imaging lens group G3 in sequence along the same optical axis from the object side to the image side. The first imaging lens group G1 specifically adopts an inclined light-transmitting flat plate 9. This design enables the system to reflect ghost light formed by reflection from the lens surface to an area that cannot be observed by the human eye, thereby effectively reducing the impact of ghosting on the clarity of the projected image.

[0088] Furthermore, the second and third imaging lens groups G2 and G3, through their respective specific optical power configurations (φ2' and φ3'), and the fact that the total optical power φ of the system satisfies the relationship 0.01≤|φ2'-φ3'| / φ≤2, collectively significantly improve the overall imaging quality of the system. The second imaging lens group G2 corrects the system's geometric aberrations, ensuring sharpness and accuracy of image edges. The third imaging lens group G3 further optimizes light distribution and utilization efficiency by controlling the beam angle, improving the overall optical efficiency of the system.

[0089] Thus, the optical projection system provided by the embodiments of the present application not only effectively reduces ghosting and 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 luminous angle control. This system is not only suitable for AR display devices, providing high-quality projection display support for augmented reality technology, but can also be widely used in other occasions requiring high-quality projection display, such as projectors and virtual reality devices.

[0090] In some examples of the present application, the light-transmitting flat plate 9 forms an angle θ with a direction perpendicular to the optical axis, and θ is ≥ 8°.

[0091] In optical projection systems, ghost images are a key factor affecting image quality. They are primarily caused by stray light reflected from lens surfaces. Especially near the aperture, the reflected light can easily form a secondary image, reducing image contrast and clarity. To address this issue, this example of the present application proposes an optical solution to suppress ghost images by optimizing the tilt angle of the light-transmitting plate 9 relative to the vertical direction (perpendicular to the optical axis), namely, the angle θ mentioned in this example.

[0092] Necessity of angle θ ≥ 8°:

[0093] By setting the tilt angle of light-transmitting plate 9 to ≥8°, the present application fully utilizes the reflective properties of light on inclined surfaces. Specifically, when light strikes the tilted light-transmitting plate 9 at a certain angle, its reflected light is directed to an area that cannot be directly observed by the human eye, effectively reducing the possibility of reflected light that forms ghost images entering the imaging optical path.

[0094] While ensuring ghost suppression, this application also takes into account the overall design and performance balance of the optical projection system. While an excessively large angle θ (e.g., θ > 14°) can further reduce ghosting, it can introduce asymmetric aberrations (such as coma and astigmatism), affecting the clarity of the peripheral field of view. Furthermore, increasing the angle θ increases the spacing between the imaging lens groups, increasing the total optical length (TTL) of the entire optical projection system, potentially affecting the system's compactness and portability.

[0095] More importantly, if the angle θ is too large, it may cause light loss during transmission, reducing the light efficiency of the system.

[0096] In a more preferred example, the light-transmitting flat plate 9 forms an angle θ with the perpendicular direction of the optical axis, and 8°≤θ≤14°.

[0097] The optical design in this example of the present application effectively reduces ghosting, which directly improves the imaging quality of the projected image, making the image clearer and with higher contrast.

[0098] The optical design in this example of the present application avoids other optical performance problems introduced by excessively large tilt angles by reasonably controlling the value of θ, thereby ensuring the overall stability of the system performance.

[0099] For example, if higher ghost suppression is required, θ = 12° or 14° can be selected. If system compactness is a high requirement, θ = 8° can be selected.

[0100] In summary, by optimizing the tilt angle of the light-transmitting plate 9, this application not only effectively suppresses ghosting and significantly improves imaging quality, but also controls the total track length (TTL) of the optical projection system. This design ensures high-quality imaging while also maintaining system compactness.

[0101] In some examples of this application, see 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; and the prism 2 is located between the display screen 1 and the third imaging lens group.

[0102] In addition to the three imaging lens assemblies described above, the optical projection system provided in this embodiment also includes a display screen 1 and a prism 2. Display screen 1 is positioned on the image side of the optical projection system. Display screen 1 is the source of image information and is responsible for outputting the content to be projected.

[0103] The prism 2 is positioned between the display screen 1 and the third imaging lens assembly, playing a key role in deflecting and guiding light. In this application, the prism can change the propagation direction of light, allowing light emitted from the display screen 1 to enter the subsequent imaging lens assembly at an appropriate angle and path. This is crucial for optimizing optical path design, reducing light loss, and improving imaging quality.

[0104] By introducing the prism 2, the optical projection system of the present application achieves flexible light path switching, allowing light emitted from the display screen 1 to more efficiently enter the subsequent imaging lens assembly. This design not only reduces the transmission distance and loss of light, but also improves light utilization, thereby helping to improve overall imaging efficiency.

[0105] The material of the prism 2 can be selected from high-transmittance glass (such as BK7, with a refractive index n≈1.52) to reduce interface reflection loss.

[0106] In some examples of this application, see Figure 1 The lens closest to the display screen 1 in the second imaging lens group G2 has negative optical power.

[0107] In this example of the present application, the lens closest to the display screen 1 in the second imaging lens group G2 (eg Figure 1 The third lens 5) shown in FIG has negative optical power. This design plays an important role in optimizing the telecentricity performance of the entire optical projection system.

[0108] When light emitted from the display screen 1 is refracted 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 (e.g., its optical power value is approximately -0.12), it will have the following significant effects on the chief light:

[0109] The divergent nature of the negative power lens moderately deflects the chief light rays at the edges of the field of view outward. This effect effectively offsets the increased angle of incidence caused by compact system designs (e.g., TTL < 15mm), ensuring that the light is in an ideal propagation state before entering the subsequent lens group.

[0110] By carefully designing the curvature radius, thickness and specific position of the negative lens in the system, the angle of the main light can be precisely controlled. Ultimately, the angle of the main light emitted from the second imaging lens group G2 is strictly controlled within 1° (see the specific optical path diagram for details). Figure 1 ), thereby significantly optimizing the telecentricity performance of the optical projection system.

[0111] The negative-power lens (e.g., third lens 5) in the second imaging lens group G2, located near the display screen 1, does not exist in isolation; instead, it works closely with the positive-power lenses (e.g., first lens 3 and second lens 4) in the third imaging lens group G3. This synergy ensures that the overall light propagation path within the system is neither excessively divergent (resulting in reduced light efficiency) nor excessively convergent (increasing aberrations). Specifically, the total optical power φ of the entire optical projection system must strictly satisfy the condition 0.01 ≤ |φ2' - φ3'| / φ ≤ 2 to achieve an optimal balance between telecentricity and aberrations.

[0112] In summary, by designing the lens closest to the display screen 1 in the second imaging lens group G2 with negative optical power and precisely controlling its divergence effect, telecentricity compensation, and synergy with the third imaging lens group G3, the optical projection system of the present application achieves significant optimization of telecentricity. This design not only improves the system's imaging quality but also enhances its adaptability and stability within a compact design.

[0113] In some examples of the present application, the telecentricity Tele of the optical projection system satisfies: Tele<1°, where Tele is the angle of emergence of the main light of the optical projection system from the display screen 1 .

[0114] In optical projection systems, telecentricity (Tele) is an indicator that measures the degree of parallelism between the chief ray (Chief Ray) and the optical axis. It directly affects the quality of the projected image, specifically in terms of brightness uniformity, color consistency, and imaging distortion.

[0115] Regarding brightness uniformity: Deviation in the main light angle will cause vignetting at the edges of the image, affecting the overall brightness distribution of the projected image.

[0116] Color consistency: Light emitted at a large angle can easily cause chromatic aberration, making the projected image inconsistent in different color channels.

[0117] Imaging distortion: Non-telecentric systems will aggravate image distortion, causing the projected image to have a certain degree of distortion in shape.

[0118] 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:

[0119] (1) Negative optical power design in the second imaging lens group G2:

[0120] The lens closest to the display screen 1 in the second imaging lens group G2 is designed to have negative optical power, which can effectively diverge marginal light and compensate for the increased incident angle caused by the compact system design (such as the total optical length TTL <15mm), thereby reducing the telecentricity Tele.

[0121] (2) Adjustment of the refractive interface of the prism 2:

[0122] The prism 2 adjusts the main light angle through its refractive interface, which can further optimize the propagation path of the light, and also helps to reduce the telecentricity Tele.

[0123] (3) The positive focal power configuration of the third imaging lens group G3:

[0124] The third imaging lens group G3 adopts a positive optical power configuration, and its converging effect enables the main light to be parallel to the optical axis, ensuring the optimization of the overall telecentricity of the system.

[0125] These key technologies work together to ensure the telecentricity of the optical projection system provided by the embodiments of this application is less than 1°. This optimized telecentricity not only improves the clarity of the projected image and reduces aberrations (such as distortion and field curvature) caused by light tilt, but also ensures a more consistent projection image across all fields of view, providing users with an optimal visual experience, whether in the center or at the edges.

[0126] Specifically, when telecentricity is low, the principal light rays are more parallel to the optical axis, effectively reducing various aberrations caused by light tilt, making the projected image more detailed and realistic. Furthermore, the low telecentricity design enhances the brightness uniformity and color consistency of the projected image, further improving user satisfaction.

[0127] In summary, the present application achieves the optical optimization goal of telecentricity Tele<1° of the optical projection system by comprehensively utilizing key optical technologies such as the negative optical focal length design of the second imaging lens group G2, the refractive interface adjustment of the prism 2, and the positive optical focal length configuration of the third imaging lens group G3, thereby significantly improving the quality of the projected image and the user experience.

[0128] In some examples of this 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, wherein: 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 focal length of the third lens 5 is negative.

[0129] The optical projection system provided in the present embodiment features a second imaging lens group G2 and a third imaging lens group G3 in its imaging portion. These two imaging lens groups work together to ensure high system performance. Specifically, these two imaging lens groups contain a total of six lenses: 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. This six-lens combination is designed to achieve high definition, low distortion, and excellent color reproduction capabilities for the optical projection system, thereby providing users with an exceptional visual experience.

[0130] See also Figure 1 and Figure 12 The third imaging lens group G3 is designed to consist of the first lens 3 and the second lens 4; the second imaging lens group G2 is designed to consist of the third lens 5 to the sixth lens 8.

[0131] It's worth noting that the third lens element 5, closest to the display screen 1 in the second imaging lens group G2, has a negative optical power. In this configuration, the negative optical power of the third lens element 5 helps diverge marginal light, compensating for the increased angle of incidence that may arise from a compact system design (e.g., a TTL < 15mm), thereby reducing telecentricity and improving brightness uniformity and color consistency in the projected image.

[0132] The third imaging lens group G3 is primarily responsible for modulating the light angle, improving the overall optical projection system's light efficiency; while the second imaging lens group G2 focuses on correcting geometric aberrations to enhance image quality. The collaborative work of these two imaging lens groups ensures the optimization of the overall performance of the optical system.

[0133] By precisely controlling the optical focal length and arrangement of each lens, this example of the present application achieves the optimization goal of telecentricity Tele<1°, reduces the aberration caused by light tilt, and improves the clarity and consistency of the projected image.

[0134] In some examples of this application, see Figure 7 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, wherein: 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.

[0135] The optical projection system provided in the present embodiment features a second imaging lens group G2 and a third imaging lens group G3 in its imaging portion. These two imaging lens groups work together to ensure high system performance. Specifically, these two imaging lens groups contain a total of six lenses: 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. This six-lens combination is designed to achieve high definition, low distortion, and excellent color reproduction capabilities for the optical projection system, thereby providing users with an exceptional visual experience.

[0136] See also Figure 7 In this example, the second imaging lens group G2 and the third imaging lens group G3 are divided as follows: the third imaging lens group G3 consists of the first lens 3 to the third lens 5; the second imaging lens group G2 consists of the fourth lens 6 to the sixth lens 8. It is worth noting that the fourth lens 6 in the second imaging lens group G2, which is closest to the display screen 1, has a negative optical power. This design also serves to diverge marginal light and reduce telecentricity.

[0137] and Figure 1 and Figure 12 Compared to the example shown, Figure 7 In this example, the third imaging lens group G3, because it includes more lenses (i.e., the first lens 3 through the third lens 5), is responsible for more luminous angle modulation and light efficiency enhancement. Meanwhile, the second imaging lens group G2 is still used to correct geometric aberrations. This functional division and adjustment results in more balanced and optimized overall performance of the optical projection system.

[0138] Despite Figure 7 In this example, the position of the negative power lens is changed from the third lens 5 to the fourth lens 6 compared to other examples. However, this 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, reasonable aberration correction measures are used to ensure that the clarity and consistency of the projected image are not affected.

[0139] In summary, the above two examples ( Figure 1 and Figure 12 Example with Figure 7 This example demonstrates how optical projection systems can optimize telecentricity and improve overall performance using different imaging lens group configurations and specific lens power configurations. By precisely controlling the power and arrangement of each lens, and rationally dividing the imaging lens group, telecentricity can be effectively reduced, minimizing aberrations and significantly improving the clarity and consistency of the projected image.

[0140] In some examples of this application, see Figure 1 and Figure 2 , the maximum thickness T1 and the minimum thickness T2 of the first lens 3 satisfy: 1.3≤T1 / T2≤1.6.

[0141] First, from the perspective of optimizing optical performance, precisely controlling the thickness ratio of different regions of the first lens 3 (particularly the central and peripheral regions) can significantly reduce aberrations in the optical projection system, particularly spherical aberration and coma. This is because the shape of the lens and its thickness distribution have a direct impact on the light propagation path and focusing characteristics. When the T1 / T2 ratio is maintained within the range of 1.3 to 1.6, the first lens 3 can more effectively guide light and reduce deviation during light propagation, thereby significantly improving image quality.

[0142] Secondly, while ensuring optical performance, constraining the thickness ratio of different regions of the first lens 3 also helps to achieve miniaturization of the optical projection system. As the largest and thickest lens in the system, the size of the first lens 3 has a significant impact on the volume of the entire system. By optimizing its thickness ratio, the volume of the lens can be effectively reduced without sacrificing image quality, thereby reducing the size and weight of the entire optical projection system.

[0143] In summary, the thickness ratio design of the first lens 3 in this example of the present application fully demonstrates the pursuit of a balance between optical performance and system compactness. On the one hand, by optimizing the lens shape, aberrations are reduced and imaging quality is improved; on the other hand, by controlling the lens size, system miniaturization is achieved. This balanced design enables the optical projection system to meet high performance requirements while also better adapting to diverse application scenarios, demonstrating excellent practicality and adaptability.

[0144] In some examples of the present application, the optical power of each lens satisfies:

[0145] The optical power φ1 of the first lens 3 satisfies: 0.1<φ1<0.2;

[0146] The refractive power φ2 of the second lens 4 satisfies: -0.08<φ2<0.05;

[0147] The refractive power φ3 of the third lens 5 satisfies: -0.18<φ3<-0.05;

[0148] The refractive power φ4 of the fourth lens 6 satisfies: -0.15<φ4<-0.01;

[0149] The refractive power φ5 of the fifth lens 7 satisfies: -0.01<φ5<0.02;

[0150] The refractive power φ6 of the sixth lens 8 satisfies the following: 0.16<φ6<0.17.

[0151] The optical focal length design used in this application can achieve: aberration correction (spherical aberration, field curvature, chromatic aberration), maximization of light efficiency and telecentricity control (Tele<1°).

[0152] Specifically, the first lens 3 has a focal power range of 0.1 < φ1 < 0.2. It is the primary converging lens in the entire optical path, playing a major role in improving light efficiency. It can also compensate for astigmatism introduced by the prism.

[0153] The focal power of the second lens 4 is in the range of -0.08 < φ2 < 0.05. The focal power of the second lens 4 can be positive or negative, selected within the above range based on specific needs. The second lens 4 can be used to balance the focal power of the first lens 3 and the third lens 5. The focal power design of the second lens 4 can also suppress distortion.

[0154] The third lens 5 has a focal power range of -0.18 < φ3 < -0.05. It is a negative lens that can be used to control the system's telecentricity. The focal power design of the third lens 5, combined with its high refractive index, can offset field curvature and significantly reduce the system's telecentricity.

[0155] The fourth lens 6 has a focal power range of -0.15<φ4<-0.01. It is a negative lens and can also be used to control the telecentricity of the system and correct aberrations.

[0156] The fifth lens 7 has a focal power range of -0.01<φ5<0.02 and can be used in conjunction with the fourth lens 6 or the subsequent sixth lens 8 to achieve aberration correction.

[0157] The sixth lens 8 has an optical power range of 0.16<φ6<0.17. The sixth lens 8 is used to control the imaging position and can be combined with other lenses to control vertical axis chromatic aberration.

[0158] The optical power ratio of the third lens 5 to the sixth lens 8 is 0.3<|φ3 / φ6|<1.1, which can avoid image curvature caused by a strong negative lens.

[0159] The optical power ratio of the first lens 3 to the fourth lens 6 is |φ1 / φ4|>0.67, which can ensure that the main converging ability is not excessively offset.

[0160] In some examples of the present application, a ratio of a maximum effective optical diameter Dmax of a lens in the optical projection system to a total optical length TTL of the optical projection system satisfies: 0.4≤Dmax / TTL≤0.55; wherein TTL<15 mm.

[0161] In this example of the present application, by controlling the Dmax / TTL ratio, we can ensure sufficient optical effective diameter to collect light and improve image brightness and contrast while avoiding the increased system weight and cost caused by an excessively large lens diameter. A reasonable Dmax / TTL ratio helps optimize the light propagation path and reduce light loss at the lens edges, thereby improving overall light efficiency.

[0162] The optical projection system provided in the embodiments of the present application has a total optical length (TTL) of less than 15 mm, which directly promotes the miniaturization of the optical projection system. Combined with the Dmax / TTL ratio range, the overall system size can be effectively controlled while maintaining optical performance. This compact design makes the optical projection system more suitable for a wider range of space-constrained applications.

[0163] The present invention provides an optical path of an optical projection system (see Figure 1 )as follows:

[0164] Starting from the image side, light is first emitted by display screen 1, then enters and passes through prism 2 for initial optical path deflection or adjustment. Next, the light 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 light-transmitting plate 9. Each optical lens performs a specific optical function, such as focusing and correcting aberrations, and they work together to ensure accurate light transmission and image quality. Finally, the processed light is emitted from the light-transmitting plate 9 and accurately reaches the aperture 01. The surface of the aperture 01 serves as an important control interface for the optical path, further limiting or adjusting the light. Afterwards, the optical projection system can also be connected to other optical components according to actual needs to expand its functions or adapt to different application scenarios.

[0165] The optical projection system provided in the embodiment of the present application includes six lenses: the first lens 3 to the sixth lens 8. The refractive index n and the dispersion coefficient v of these six lenses are in the range of: 1.4 <n<2.0,20<v<75。

[0166] In one example, see Figure 1 and Figure 12 The refractive index of the first lens 3 is n=1.54, and the dispersion coefficient v=56.3; the refractive index of the second lens 4 is n=1.54, and the dispersion coefficient v=56.3; the refractive index of the third lens 5 is n=1.65, and the dispersion coefficient v=23; the refractive index of the fourth lens 6 is n=1.65, and the dispersion coefficient v=23; the refractive index of the fifth lens 7 is n=1.54, and the dispersion coefficient v=56.3; the refractive index of the sixth lens 8 is n=1.78, and the dispersion coefficient v=47.

[0167] In one example, see Figure 7 The refractive index of the first lens 3 is n=1.54, and the dispersion coefficient v=56.3; the refractive index of the second lens 4 is n=1.54, and the dispersion coefficient v=56.3; the refractive index of the third lens 5 is n=1.65, and the dispersion coefficient v=23; the refractive index of the fourth lens 6 is n=1.65, and the dispersion coefficient v=23; the refractive index of the fifth lens 7 is n=1.54, and the dispersion coefficient v=56.3; the refractive index of the sixth lens 8 is n=1.8, and the dispersion coefficient v=47.

[0168] The surface of each lens in the optical projection system can be aspherical or spherical, and has an anti-reflection film layer on the surface.

[0169] The optical projection system of the present application is described below through Examples 1 to 3 respectively.

[0170] Example 1

[0171] The optical projection system provided in this embodiment 1 is shown in FIG. Figure 1 and Figure 2 , including, along the same optical axis from the object side to the image side, 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;

[0172] The first imaging lens group G1 includes a light-transmitting plate 9 that is tilted, and the light-transmitting plate 9 forms an angle θ with the vertical direction of the optical axis, and θ is 8°;

[0173] The third imaging lens group G3 includes a first lens 3 and a second lens 4;

[0174] 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; wherein the optical power of the third lens 5 is negative;

[0175] The optical power φ1 of the first lens 3 is 0.148;

[0176] The optical power φ2 of the second lens 4 is -0.037;

[0177] The optical power φ3 of the third lens 5 is -0.171;

[0178] The optical power φ4 of the fourth lens 6 is -0.033;

[0179] The optical power φ5 of the fifth lens 7 is 0.001;

[0180] The refractive power φ6 of the sixth lens 8 is 0.162.

[0181] The optical parameters of the optical projection system provided in this embodiment 1 are shown in Table 1 below.

[0182] Table 1

[0183]

[0184] The optical projection system provided in this embodiment 1 has optical performance such as Figures 3 to 6 As shown: Figure 3 is a point diagram diagram. Figure 4 is the MTF curve graph, Figure 5 It is the field curvature and distortion diagram, Figure 6 This is a diagram of vertical chromatic aberration.

[0185] A spot diagram is a diffuse pattern formed when many light rays emitted from a point pass through an optical projection system. Due to aberration, their intersection with the image plane is no longer concentrated at the same point, but is spread over a certain range. It is used to evaluate the imaging quality of the projection optical projection system. Figure 3In the optical projection system provided by this embodiment 1, the maximum value of the image point in the point array diagram is less than 2 μm.

[0186] The MTF curve is a modulation transfer function graph that characterizes the imaging clarity of an optical projection system through the contrast between black and white line pairs. Figure 4 The optical projection system provided in this embodiment 1 has an MTF of >0.4 at 125lp / mm.

[0187] See also Figure 5 In the optical projection system provided in this embodiment 1, the maximum distortion occurs in 1 field of view, and the absolute value is less than 1%.

[0188] Vertical axial chromatic aberration is also called chromatic aberration of magnification. It mainly refers to the difference in the focal position of blue light and red light on the image plane when a complex main light on the object side is transformed into multiple light rays due to the dispersion of the refraction system. Figure 6 The optical projection system provided in this embodiment 1 has a maximum color difference value of less than 4 μm.

[0189] Example 2

[0190] The optical projection system provided in this embodiment 2 is shown in FIG. Figure 7 , including, along the same optical axis from the object side to the image side, 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;

[0191] The first imaging lens group G1 includes a light-transmitting plate 9 that is tilted, and the light-transmitting plate 9 forms an angle θ with the vertical direction of the optical axis, and θ is 8°;

[0192] The third imaging lens group G3 includes a first lens 3 to a third lens 5;

[0193] The second imaging lens group G2 includes fourth to sixth lenses 6 to 8, and the optical power of the third lens 5 is negative; wherein the optical power of the fourth lens 6 is negative;

[0194] The optical power φ1 of the first lens 3 is 0.103;

[0195] The optical power φ2 of the second lens 4 is 0.048;

[0196] The optical power φ3 of the third lens 5 is -0.115;

[0197] The optical power φ4 of the fourth lens 6 is -0.104;

[0198] The optical power φ5 of the fifth lens 7 is -0.006;

[0199] The optical power φ6 of the sixth lens 8 is 0.169.

[0200] The optical parameters of the optical projection system provided in this embodiment 2 are shown in Table 2 below.

[0201] Table 2

[0202]

[0203] The optical projection system provided in this embodiment 2 has optical performance such as Figures 8 to 11 As shown: Figure 8 is a point diagram diagram. Figure 9 is the MTF curve graph, Figure 10 It is the field curvature and distortion diagram, Figure 11 This is a diagram of vertical chromatic aberration.

[0204] See also Figure 8 In the optical projection system provided by this embodiment 2, the maximum value of the image point in the point array diagram is less than 2 μm.

[0205] See also Figure 9 The optical projection system provided in this embodiment 2 has an MTF of >0.4 at 125lp / mm.

[0206] See also Figure 10 In the optical projection system provided in this embodiment 2, the maximum distortion occurs in 1 field of view, and the absolute value is less than 1%.

[0207] See also Figure 11 The optical projection system provided in this embodiment 2 has a maximum color difference value of less than 4 μm.

[0208] Example 3

[0209] The optical projection system provided in this embodiment 3 is shown in FIG. Figure 12 , including, along the same optical axis from the object side to the image side, 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;

[0210] The first imaging lens group G1 includes a light-transmitting plate 9 that is tilted, and the light-transmitting plate 9 forms an angle θ with the vertical direction of the optical axis, and θ is 8°;

[0211] The third imaging lens group G3 includes a first lens 3 and a second lens 4;

[0212] 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; wherein the optical power of the third lens 5 is negative;

[0213] The optical power φ1 of the first lens 3 is 0.192;

[0214] The optical power φ2 of the second lens 4 is -0.078;

[0215] The focal power φ3 of the third lens 5 is -0.080;

[0216] The optical power φ4 of the fourth lens 6 is -0.140;

[0217] The optical power φ5 of the fifth lens 7 is 0.019;

[0218] The optical power φ6 of the sixth lens 8 is 0.160.

[0219] The optical parameters of the optical projection system provided in this embodiment 3 are shown in Table 3 below.

[0220] Table 3

[0221]

[0222] The optical projection system provided in this embodiment 3 has optical performance such as Figures 13 to 16 As shown: Figure 13 is a point diagram diagram. Figure 14 is the MTF curve graph, Figure 15 It is the field curvature and distortion diagram, Figure 16 This is a diagram of vertical chromatic aberration.

[0223] See also Figure 13 In the optical projection system provided by this embodiment 3, the maximum value of the image point in the point array diagram is less than 2 μm.

[0224] See also Figure 14 The optical projection system provided in this embodiment 3 has an MTF of >0.4 at 125lp / mm.

[0225] See also Figure 15 In the optical projection system provided in this embodiment 3, the maximum distortion occurs in 1 field of view, and the absolute value is less than 1%.

[0226] See also Figure 16 The optical projection system provided in this embodiment 3 has a maximum color difference value of less than 4 μm.

[0227] According to another embodiment of the present application, an AR display device is provided, comprising a housing and the optical projection system as described above. The optical projection system is disposed in the housing.

[0228] The AR display device provided in the embodiment of the present application is, for example, a VR head-mounted display device.

[0229] The specific implementation of the AR display device in the embodiment of the present application can refer to the various embodiments of the above-mentioned optical projection system, and therefore at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0230] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0231] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. An optical projection system, characterized in that: The lens comprises a first imaging lens group (G1), a second imaging lens group (G2) and a third imaging lens group (G3) in sequence from the object side to the image side along the same optical axis; The first imaging lens group (G1) comprises a light-transmitting flat plate (9) arranged obliquely; The second imaging lens group (G2) has an optical focal length φ2', the third imaging lens group (G3) has an optical focal length φ3', and the total optical focal length φ of the optical projection system satisfies: 0.01≤|φ2'-φ3'| / φ≤2; The optical projection system comprises 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) which are arranged in sequence along the optical axis from the image side to the object side.

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 is ≥ 8°.

3. The optical projection system according to claim 1 or 2, characterized in that: The optical projection system further comprises 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, wherein: The lens closest to the display screen (1) in the second imaging lens group (G2) has negative optical power.

5. The optical projection system according to claim 4, characterized in that: The telecentricity Tele of the optical projection system satisfies: Tele<1°, wherein Tele is the angle of emergence of the main light of the optical projection system from the display screen (1).

6. The optical projection system according to claim 4, characterized in that: The third imaging lens group (G3) comprises a first lens (3) and a second lens (4); The second imaging lens group (G2) comprises a third lens (5) to a sixth lens (8), and the optical focal length of the third lens (5) is negative.

7. The optical projection system according to claim 4, wherein: The third imaging lens group (G3) comprises a first lens (3) to a third lens (5); The second imaging lens group (G2) comprises a fourth lens (6) to a sixth lens (8), and the optical focal length 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 optical power of each lens satisfies: The focal 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 focal 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.

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

11. An AR display device, characterized in that: include: shell; and The optical projection system according to any one of claims 1 to 10.

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