Visual system

Abstract

The utility model discloses a visual system which comprises a lens cone, a lens group and a spacing element group, wherein the lens group and the spacing element group are assembled in the lens cone; the lens group comprises a first lens with positive focal power, a reflective polarizing element, a first quarter-wave plate, a second lens with negative focal power, a third lens with focal power, a partial reflection element, a second quarter-wave plate, a polarizing film and a fourth lens with focal power which are sequentially arranged from the first side to the second side along the optical axis; the spacing element group comprises a first spacing element positioned between the first lens and the second lens, a second spacing element positioned between the second lens and the third lens, and a third spacing element positioned between the third lens and the fourth lens; the interval EP01 from the first side surface of the lens barrel to the first side surface of the first spacing element along the optical axis and the center thickness CT1 of the first lens on the optical axis meet the following conditions: 1.0 lt; eP01 / CT1lt, EP01 / CT1lt; 1.7, 1.7; the inner diameter d0s of the first side surface of the lens barrel and the curvature radius R1 of the first side surface of the first lens meet the following condition: 1.75 < d0s / R1lt; and 2.3.

Description

Technical Field

[0001] The present application relates to the field of optical devices, and more specifically, to a visual system. Background Art

[0002] Currently, more and more optical lenses are applied to various devices of virtual reality technology. MR (Mixed Reality) technology is a combination of VR (Virtual Reality) and AR (Augmented Reality), which superimposes virtual content on the real world, enabling users to interact in both the real world and the virtual world. At present, MR technology has been widely applied in industries such as training and education, healthcare, industrial manufacturing, and architectural design.

[0003] With the continuous progress of technology, the head-mounted display devices and hardware of virtual reality devices will also be continuously improved, becoming lighter, smaller, more comfortable, and more powerful. The integration of various sensors, display screens, and computing units in virtual reality devices will provide users with a higher-quality and smoother experience.

[0004] Combined with the above development status of virtual reality devices, how to further improve the projection ability of the display screen of the head-mounted device to enhance the immersion and further improve the user experience has always been the goal pursued by this field. Summary of the Utility Model

[0005] The present application provides a visual system that can at least solve or partially solve at least one problem or other problems existing in the prior art.

[0006] A first aspect of the present application provides a visual system, which may include a lens barrel and a lens group and a spacer element group assembled in the lens barrel. The lens group includes, in order from the first side to the second side along the optical axis: a first lens with positive optical power, a reflective polarizing element, a first quarter-wave plate, a second lens with negative optical power, a third lens with optical power, a partially reflective element, a second quarter-wave plate, a polarizer, and a fourth lens with optical power; the spacer element group includes: a first spacer element located between the first lens and the second lens and abutting against the second side surface of the first lens, a second spacer element located between the second lens and the third lens and abutting against the second side surface of the second lens, and a third spacer element located between the third lens and the fourth lens and abutting against the second side surface of the third lens; wherein, the number of lenses with optical power in the lens group is four; the interval EP01 along the optical axis from the first side surface of the lens barrel to the first side surface of the first spacer element and the central thickness CT1 of the first lens on the optical axis satisfy: 1.0 < EP01 / CT1 < 1.7; the inner diameter d0s of the first side surface of the lens barrel and the curvature radius R1 of the first side surface of the first lens satisfy: 1.75 < d0s / R1 < 2.3.

[0007] According to an exemplary embodiment of the present application, the interval EP12 along the optical axis from the second side surface of the first spacer element to the first side surface of the second spacer element, the central thickness CT2 of the second lens on the optical axis, and the axial distance T23 from the second side surface of the second lens to the first side surface of the third lens satisfy: 0.2 < EP12 / (CT2 + T23) < 1.2.

[0008] According to an exemplary embodiment of the present application, the outer diameter D1m of the second side surface of the first spacer element and the outer diameter D2m of the second side surface of the second spacer element satisfy: 1.0 < D1m / D2m < 1.2.

[0009] According to an exemplary embodiment of the present application, the inner diameter d2s of the first side surface of the second spacer element, the inner diameter d2m of the second side surface of the second spacer element, the curvature radius R4 of the second side surface of the second lens, and the curvature radius R5 of the first side surface of the third lens satisfy: 0.2 < (d2s + d2m) / (R4 + R5) < 0.65.

[0010] According to an exemplary embodiment of the present application, the inner diameter d3s of the first side surface of the third spacer element and the central thickness CT3 of the third lens on the optical axis satisfy: 2.0 < d3s / CT3 < 2.95.

[0011] According to an exemplary embodiment of the present application, the inner diameter d0m of the second side surface of the lens barrel, the central thickness CTQ2 of the second quarter-wave plate on the optical axis, the central thickness CTL of the polarizer on the optical axis, and the central thickness CT4 of the fourth lens on the optical axis satisfy: 6.2 < d0m / (CTQ2 + CTL + CT4) < 9.9.

[0012] According to an exemplary embodiment of the present application, the inner diameter d1m of the second side surface of the first spacer element and the combined focal length fz1 of the reflective polarizing element, the first quarter-wave plate, and the second lens satisfy: -0.65 < d1m / fz1 < -0.05.

[0013] According to an exemplary embodiment of the present application, the inner diameter d3m of the second side surface of the third spacer element, the outer diameter D3m of the second side surface of the third spacer element, and the combined focal length fz2 of the second quarter-wave plate, the polarizer, and the fourth lens satisfy: 0.2 < (d3m + D3m) / |fz2| < 1.0.

[0014] According to an exemplary embodiment of the present application, the outer diameter D3s of the first side surface of the third spacer element and the curvature radius R6 of the second side surface of the third lens satisfy: -0.3 < D3s / R6 < 0.

[0015] According to an exemplary embodiment of the present application, the outer diameter D0s of the first side surface of the lens barrel, the outer diameter D0m of the second side surface of the lens barrel, and the interval L along the optical axis from the first side surface of the lens barrel to the second side surface of the lens barrel satisfy: 0.15 < (D0s - D0m) / L < 0.55.

[0016] According to an exemplary embodiment of the present application, the maximum thickness CP2 of the second spacer element, the interval EP23 along the optical axis from the second side surface of the second spacer element to the first side surface of the third spacer element, the central thickness CT3 of the third lens on the optical axis, and the axial distance T34 from the second side surface of the third lens to the first side surface of the fourth lens satisfy: 0.8 < (CP2 + EP23) / (CT3 + T34) < 2.2.

[0017] According to an exemplary embodiment of the present application, the outer diameter D2s of the first side surface of the second spacer element and the effective focal length f2 of the second lens satisfy: -0.85 < D2s / f2 < -0.1.

[0018] According to an exemplary embodiment of the present application, the maximum thickness CP1 of the first spacer element and the maximum thickness CP3 of the third spacer element satisfy: 0.4 < CP1 / CP3 < 1.05.

[0019] According to an exemplary embodiment of the present application, the inner diameter d1s of the first side surface of the first spacer element, the outer diameter D1s of the first side surface of the first spacer element, and the effective focal length f1 of the first lens satisfy: 1.05 < (d1s + D1s) / f1 < 2.2.

[0020] A second aspect of the present application provides a visual system, which may include a lens barrel and a lens group and a spacer element group assembled in the lens barrel. The lens group includes, in order from the first side to the second side along the optical axis: a first lens with positive optical power, a reflective polarizing element, a first quarter-wave plate, a second lens with negative optical power, a third lens with optical power, a partially reflective element, a second quarter-wave plate, a polarizer, and a fourth lens with optical power; the spacer element group includes: a first spacer element located between the first lens and the second lens and abutted against the second side surface of the first lens, a second spacer element located between the second lens and the third lens and abutted against the second side surface of the second lens, and a third spacer element located between the third lens and the fourth lens and abutted against the second side surface of the third lens; wherein, the number of lenses with optical power in the lens group is four; the interval EP01 along the optical axis from the first side surface of the lens barrel to the first side surface of the first spacer element and the central thickness CT1 of the first lens on the optical axis satisfy: 1.0 < EP01 / CT1 < 1.7; the inner diameter d1s of the first side surface of the first spacer element, the outer diameter D1s of the first side surface of the first spacer element, and the effective focal length f1 of the first lens satisfy: 1.05 < (d1s + D1s) / f1 < 2.2.

[0021] The visual system according to the above embodiment of the present application adopts a catadioptric scheme including four lenses, and by adopting a polarized catadioptric optical path method, it can better compress the body height and improve the imaging quality; at the same time, by adopting at least one spacer element and reasonably distributing the parameters of each lens and each spacer element, it is possible to achieve at least one of reducing the stray light risk of the visual system, improving the processing formability, assembly stability and imaging quality of the visual system.

[0022] The visual system according to an exemplary embodiment of the present application can satisfy the conditional expressions 1.0 < EP01 / CT1 < 1.7 and 1.75 < d0s / R1 < 2.3. By reasonably controlling EP01 / CT1 and d0s / R1 within a reasonable range, the edge thickness and central thickness of the first lens are at a reasonable level, which is beneficial to improving the forming stability of the first lens; at the same time, it is beneficial to improve the light converging ability of the first lens under the condition of satisfying the processability of the first lens, thereby improving the imaging quality and clarity and enhancing the visual experience.

[0023] The visual system according to an exemplary embodiment of the present application can satisfy the conditions of 1.0 < EP01 / CT1 < 1.7 and 1.05 < (d1s + D1s) / f1 < 2.2. By reasonably controlling EP01 / CT1 and (d1s + D1s) / f1 within a reasonable range, the edge thickness and center thickness of the first lens are at a reasonable level, which is beneficial to improving the forming stability of the first lens. At the same time, by controlling the ratio of the sum of the inner diameter and outer diameter of the first side surface of the first spacer element to the effective focal length of the first lens within a reasonable range, it is beneficial to reduce the generation of stray light in the system and improve the imaging quality of the system on the basis of ensuring its processability. Further, by providing the first spacer element, it is beneficial to improve the anti-vibration and drop reliability of the lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects, and advantages of the present application will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings. Among them:

[0025] Figure 1 FIG. shows the structure and partial parameter schematic diagram of the visual system according to an exemplary embodiment of the present application;

[0026] Figure 2 FIG. shows the structural schematic diagram of the visual system according to Embodiment 1 of the present application;

[0027] Figure 3 FIG. shows the structural schematic diagram of the visual system according to Embodiment 2 of the present application;

[0028] Figure 4 FIG. shows the structural schematic diagram of the visual system according to Embodiment 3 of the present application;

[0029] Figure 5A 、 Figure 5B and Figure 5C respectively show the axial chromatic aberration curve, astigmatism curve, and distortion curve of the visual system according to Embodiment 1, 2, or 3 of the present application;

[0030] Figure 6 FIG. shows the MTF curve of the visual system according to Embodiment 1, 2, or 3 of the present application;

[0031] Figure 7 FIG. shows the structural schematic diagram of the visual system according to Embodiment 4 of the present application;

[0032] Figure 8 FIG. shows the structural schematic diagram of the visual system according to Embodiment 5 of the present application;

[0033] Figure 9 FIG. shows the structural schematic diagram of the visual system according to Embodiment 6 of the present application;

[0034] Figure 10A, Figure 10B and Figure 10C respectively show the axial chromatic aberration curve, astigmatism curve and distortion curve of the visual system according to Embodiment 4, 5 or 6 of the present application;

[0035] Figure 11 shows the MTF curve of the visual system according to Embodiment 4, 5 or 6 of the present application;

[0036] Figure 12 shows the structural schematic diagram of the visual system according to Embodiment 7 of the present application;

[0037] Figure 13 shows the structural schematic diagram of the visual system according to Embodiment 8 of the present application;

[0038] Figure 14 shows the structural schematic diagram of the visual system according to Embodiment 9 of the present application;

[0039] Figure 15A , Figure 15B and Figure 15C respectively show the axial chromatic aberration curve, astigmatism curve and distortion curve of the visual system according to Embodiment 7, 8 or 9 of the present application; and

[0040] Figure 16 shows the MTF curve of the visual system according to Embodiment 7, 8 or 9 of the present application. Detailed Description of the Invention

[0041] To better understand the present application, more detailed descriptions of various aspects of the present application will be made with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of the exemplary embodiments of the present application and do not limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0042] It should be noted that in this specification, the expressions such as first, second, third, fourth, etc. are only used to distinguish one feature from another feature and do not represent any limitation on the features. Therefore, without departing from the teachings of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0043] In the drawings, for the sake of convenience of explanation, the thickness, size and shape of the lens have been slightly exaggerated. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the spherical or aspherical surfaces shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0044] In this text, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region.

[0045] It should also be understood that the terms "comprises", "comprising", "has", "including" and / or "including having", when used in this specification, denote the presence of the stated features, elements and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. Further, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of listed features rather than individual elements in the list. Further, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". Also, the term "exemplary" is intended to refer to an example or illustration.

[0046] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0047] It should be noted that, without conflict, the embodiments and features in the embodiments of this application may be combined with each other. The following embodiments only represent several implementation manners of this application, and their descriptions are relatively specific and detailed, but should not be construed as a limitation on the patent scope of this application. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can be made, and these all belong to the protection scope of this application. For example, the lens groups (i.e., the first lens to the fourth lens), barrel structures and spacer elements in the embodiments of this application can be arbitrarily combined, and it is not limited that the lens group in one embodiment can only be combined with the barrel structure, spacer element, etc. in this embodiment.

[0048] The features, principles and other aspects of this application will be described in detail below.

[0049] Figure 1 It is a schematic diagram of the structural arrangement and partial parameters of a visual system according to an exemplary embodiment of the present application. Refer to Figure 1, CP1 represents the maximum thickness of the first spacer element, CP2 represents the maximum thickness of the second spacer element, CP3 represents the maximum thickness of the third spacer element, EP01 represents the distance along the optical axis from the first side surface of the lens barrel to the first side surface of the first spacer element, EP12 represents the distance along the optical axis from the second side surface of the first spacer element to the first side surface of the second spacer element, EP23 represents the distance along the optical axis from the second side surface of the second spacer element to the first side surface of the third spacer element, L represents the distance along the optical axis from the first side surface of the lens barrel to the second side surface of the lens barrel (L can also be referred to as the maximum length of the lens barrel), D0s represents the outer diameter of the first side surface of the lens barrel, d0s represents the inner diameter of the first side surface of the lens barrel, D1s represents the outer diameter of the first side surface of the first spacer element, d1s represents the inner diameter of the first side surface of the first spacer element, D2s represents the outer diameter of the first side surface of the second spacer element, d2s represents the inner diameter of the first side surface of the second spacer element, D3s represents the outer diameter of the first side surface of the third spacer element, d3s represents the inner diameter of the first side surface of the third spacer element, d0m represents the inner diameter of the second side surface of the lens barrel, D1m represents the outer diameter of the second side surface of the first spacer element, d1m represents the inner diameter of the second side surface of the first spacer element, D2m represents the outer diameter of the second side surface of the second spacer element, d2m represents the inner diameter of the second side surface of the second spacer element, d3m represents the inner diameter of the second side surface of the third spacer element, D3m represents the outer diameter of the second side surface of the third spacer element, and so on.

[0050] Reference Figures 2 to 4 , Figures 7 to 9 and Figures 12 to 14 , a first aspect of the present application provides a visual system, which may include a lens group, a spacer element group, and a lens barrel, wherein both the lens group and the spacer element group are assembled in the lens barrel.

[0051] In an exemplary embodiment, the lens barrel P0 may include a first side surface, a second side surface, an outer ring surface, and an inner ring surface. Among them, the first side surface of the lens barrel may be, for example, the end face closest to the first side, and the second side surface of the lens barrel may be, for example, the end face closest to the second side; in the direction perpendicular to the optical axis, the surface of the lens barrel farthest from the optical axis is the outer ring surface, and the surface of the lens barrel closest to the optical axis is the inner ring surface.

[0052] In an exemplary embodiment, the lens group may be a four-piece lens group, which may include, in order from the first side to the second side along the optical axis: a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown in the figure), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4. An air gap may be provided between any adjacent lenses. In an exemplary embodiment, a display screen may also be included on the second side of the visual system.

[0053] In an exemplary embodiment, the first side of the visual system may be, for example, the side closer to the human eye, and the second side may be, for example, the side closer to the display. Correspondingly, each optical element (the first lens, the reflective polarizing element, the first quarter-wave plate, the second lens, the third lens, the partial reflection element, the second quarter-wave plate, the polarizer, the fourth lens, etc.) has at least one first side surface relatively closer to the human eye side and at least one second side surface relatively closer to the display side.

[0054] In an exemplary embodiment, the first lens E1 may have a positive optical power. The first side surface of the first lens E1 may be convex, and the second side surface may be convex or concave.

[0055] In an exemplary embodiment, the second lens E2 may have a negative optical power. The first side surface of the second lens E2 may be flat, and the second side surface may be concave. The first quarter-wave plate QWP1 may be disposed on the first side surface (the surface closer to the human eye) of the second lens E1 and at least partially adhered to the first side surface of the second lens E1. The reflective polarizing element RP may be disposed on the first side surface (the surface closer to the human eye) of the first quarter-wave plate QWP1 and at least partially adhered to the first side surface of the first quarter-wave plate QWP1. Exemplarily, the first quarter-wave plate QWP1 and the reflective polarizing element RP may be sequentially adhered to the first side surface of the second lens E2, or the two may be combined together to achieve one-time adhesion, thereby improving production efficiency and reducing costs; at the same time, combining the two together can also avoid the angular deviation between the optical axis of the reflective polarizing element and the optical axis of the first quarter-wave plate caused by the adhesion process and improve the imaging quality.

[0056] In an exemplary embodiment, the third lens E3 may have a positive optical power or a negative optical power. The first side surface of the third lens E3 may be convex or concave, and the second side surface may be convex. The partial reflection element BS may be disposed on the second side surface of the third lens E3 and at least partially adhered to the second side surface of the third lens E3.

[0057] In an exemplary embodiment, the fourth lens E4 may have a positive optical power or a negative optical power. The first side surface of the fourth lens E4 may be flat, and the second side surface may be concave or convex. The polarizer LP may be disposed on the first side surface (the surface closer to the human eye) of the fourth lens E4 and at least partially adhered to the first side surface of the fourth lens E4. The second quarter-wave plate QWP2 may be disposed on the first side surface (the surface closer to the human eye) of the polarizer LP and at least partially adhered to the first side surface of the polarizer LP. Exemplarily, the polarizer LP and the second quarter-wave plate QWP2 may be sequentially adhered to the first side surface of the fourth lens E4.

[0058] In the visual system according to an exemplary embodiment of the present application, when light passes through a reflective polarizing element, the reflective polarizing element can reflect light in a certain direction and transmit light orthogonal to the reflected light. A quarter-wave plate can be used to convert between circularly polarized light and linearly polarized light to achieve the folding back of the optical path. The partial reflection element can be a partial reflection layer (such as a semi-transmissive and semi-reflective film) attached or deposited on the second side surface of the third lens, and the partial reflection layer has a semi-transmissive and semi-reflective effect on light. The function of the polarizer is to convert the natural light emitted by the screen into linearly polarized light. The image light from the display screen is finally projected onto the user's eyes after multiple refractions and reflections by the visual system.

[0059] The visual system provided according to the embodiment of the present application can be applied to the head-mounted device of virtual reality devices such as VR, AR, or MR devices. Specifically, it can be used as the visual system of the head-mounted device. By folding back the optical path, the body length of the lens can be compressed, so that the center of gravity of the head-mounted device moves backward, increasing the consumer experience.

[0060] In the exemplary embodiment, the spacer element group may include one or more of a first spacer element, a second spacer element, and a third spacer element. The first spacer element may be located between the first lens and the second lens and abut against the second side surface of the first lens. The second spacer element may be located between the second lens and the third lens and abut against the second side surface of the second lens. The third spacer element may be located between the third lens and the fourth lens and abut against the second side surface of the third lens. Reasonable use of spacer elements can effectively avoid the risk of stray light, reduce the interference to the image quality, and thus improve the imaging quality of the visual system; it is also beneficial to improve the assembly stability of the system, thereby ensuring that the system has good structural performance.

[0061] In the exemplary embodiment, at least one trimmed lens may be included in the lens group. The outer peripheral surface of the trimmed lens may have a trimmed portion and an untrimmed portion, and the outer diameter of the trimmed portion of the lens is smaller than the outer diameter of the untrimmed portion of the lens. When the outer peripheral surface of the lens has a trimmed portion, the outer diameter of the lens generally refers to the outer diameter of the untrimmed portion of the lens, and the outer diameter of the spacer element generally refers to the maximum outer diameter of the untrimmed part.

[0062] In an exemplary embodiment, the distance EP01 along the optical axis from the first side surface of the lens barrel to the first side surface of the first spacer element and the central thickness CT1 of the first lens on the optical axis may satisfy: 1.0 < EP01 / CT1 < 1.7; the inner diameter d0s of the first side surface of the lens barrel and the curvature radius R1 of the first side surface of the first lens may satisfy: 1.75 < d0s / R1 < 2.3. By reasonably controlling EP01 / CT1 and d0s / R1 within a reasonable range to meet the conditional expressions 1.0 < EP01 / CT1 < 1.7 and 1.75 < d0s / R1 < 2.3, the edge thickness and central thickness of the first lens are at a reasonable level, which is beneficial to improving the forming stability of the first lens; at the same time, it is beneficial to improving the light beam convergence ability of the first lens under the condition of meeting the processability of the first lens, thereby improving the imaging quality and clarity and enhancing the visual experience.

[0063] In an exemplary embodiment, the distance EP12 along the optical axis from the second side surface of the first spacer element to the first side surface of the second spacer element, the central thickness CT2 of the second lens on the optical axis, and the axial distance T23 from the second side surface of the second lens to the first side surface of the third lens may satisfy: 0.2 < EP12 / (CT2 + T23) < 1.2. Meeting this conditional expression helps to control the edge thickness of the second spacer element. Combining with controlling the central thickness and clearance of the second lens helps to control the overall wall thickness uniformity of the second lens and improve the forming strength of the second lens; at the same time, it is beneficial to reducing the body height, making the entire lens group more compact and realizing miniaturized design.

[0064] In an exemplary embodiment, the outer diameter D1m of the second side surface of the first spacer element and the outer diameter D2m of the second side surface of the second spacer element may satisfy: 1.0 < D1m / D2m < 1.2. Meeting this conditional expression helps to control the outer diameters of the second lens and the third lens by controlling the outer diameter of the second side surface of the first spacer element and the outer diameter of the second surface of the second spacer element, thereby controlling the assembly step difference between the second lens and the third lens and improving the assembly stability of the system.

[0065] In an exemplary embodiment, the inner diameter d2s of the first side surface of the second spacer element, the inner diameter d2m of the second side surface of the second spacer element, the curvature radius R4 of the second side surface of the second lens, and the curvature radius R5 of the first side surface of the third lens may satisfy: 0.2 < (d2s + d2m) / (R4 + R5) < 0.65. Meeting this conditional expression is beneficial to reducing the sensitivity of the second lens and the third lens, thereby improving the assembly yield; at the same time, it helps to block the stray light of the lens and improve the imaging quality of the lens.

[0066] In an exemplary embodiment, the inner diameter d3s of the first side surface of the third spacer element and the central thickness CT3 of the third lens on the optical axis may satisfy: 2.0 < d3s / CT3 < 2.95. Satisfying this conditional expression helps to ensure the surface shape stability of the second side surface of the third lens, thereby improving the forming stability of the third lens.

[0067] In an exemplary embodiment, the inner diameter d0m of the second side surface of the lens barrel, the central thickness CTQ2 of the second quarter-wave plate on the optical axis, the central thickness CTL of the polarizer on the optical axis, and the central thickness CT4 of the fourth lens on the optical axis may satisfy: 6.2 < d0m / (CTQ2 + CTL + CT4) < 9.9. Satisfying this conditional expression helps to limit the overall optical length of the system, achieve a compact design of the optical system, reduce the volume and weight of the device, and improve the wearing convenience; at the same time, it helps to ensure the strength of the second quarter-wave plate and the polarizer, and is also beneficial to the attachment of the second quarter-wave plate and the polarizer.

[0068] In an exemplary embodiment, the inner diameter d1m of the second side surface of the first spacer element and the combined focal length fz1 of the reflective polarizing element, the first quarter-wave plate, and the second lens may satisfy: -0.65 < d1m / fz1 < -0.05. Satisfying this conditional expression helps to optimize the performance of the optical system, including improving the imaging quality, enhancing the light focusing ability, and reducing or eliminating distortion, thereby improving the clarity and accuracy of the image; in addition, it also helps to control the light flux of the optical system and keep the field of view angle of the optical system at a reasonable level.

[0069] In an exemplary embodiment, the inner diameter d3m of the second side surface of the third spacer element, the outer diameter D3m of the second side surface of the third spacer element, and the combined focal length fz2 of the second quarter-wave plate, the polarizer, and the fourth lens may satisfy: 0.2 < (d3m + D3m) / |fz2| < 1.0. Satisfying this conditional expression can, on the one hand, provide a wider field of view angle, enabling users to see more virtual or augmented reality content, and on the other hand, help to block the stray light of the lens, further improving the imaging quality of the lens.

[0070] In an exemplary embodiment, the outer diameter D3s of the first side surface of the third spacer element and the curvature radius R6 of the second side surface of the third lens may satisfy: -0.3 < D3s / R6 < 0. Satisfying this conditional expression helps to control the outer diameter of the first side surface of the third lens, making the ratio between the outer diameter of the first side surface of the third lens and the curvature radius of the second side surface of the third lens within a reasonable range, which helps to control the shape of the third lens and ensure that the third lens has good processability.

[0071] In an exemplary embodiment, the outer diameter D0s of the first side surface of the lens barrel, the outer diameter D0m of the second side surface of the lens barrel, and the interval L along the optical axis from the first side surface of the lens barrel to the second side surface of the lens barrel may satisfy: 0.15 < (D0s - D0m) / L < 0.55. By satisfying this conditional expression, it helps to control the total mechanical optical length TTL of the lens to meet the module requirements and achieve miniaturization of the lens.

[0072] In an exemplary embodiment, the maximum thickness CP2 of the second spacer element, the interval EP23 along the optical axis from the second side surface of the second spacer element to the first side surface of the third spacer element, the central thickness CT3 of the third lens on the optical axis, and the axial distance T34 from the second side surface of the third lens to the first side surface of the fourth lens may satisfy: 0.8 < (CP2 + EP23) / (CT3 + T34) < 2.2. By satisfying this conditional expression, controlling the interval from the second side surface of the second spacer element to the first side surface of the third spacer element helps to control the edge thickness of the third lens. At the same time, by controlling the central thickness and clearance of the third lens, it helps to ensure the uniformity of the overall wall thickness of the third lens, improve the surface shape stability of the third lens, avoid mutual interference during the assembly process, and thus improve the assembly yield.

[0073] In an exemplary embodiment, the outer diameter D2s of the first side surface of the second spacer element and the effective focal length f2 of the second lens may satisfy: -0.85 < D2s / f2 < -0.1. By satisfying this conditional expression, it helps to control the shape of the second lens, reduce the processing and forming difficulty of the second lens, and thus further improve the processability of the second lens.

[0074] In an exemplary embodiment, the maximum thickness CP1 of the first spacer element and the maximum thickness CP3 of the third spacer element may satisfy: 0.4 < CP1 / CP3 < 1.05. By satisfying this conditional expression, controlling the ratio of the maximum thickness of the first spacer element to the maximum thickness of the third spacer element helps to control the clearance between the first lens and the second lens and the clearance between the third lens and the fourth lens. It helps to adjust the clearance by controlling the thicknesses of the first spacer element and the third spacer element during the assembly process, thereby improving the performance of the optical system and the assembly stability.

[0075] In an exemplary embodiment, the inner diameter d1s of the first side surface of the first spacer element, the outer diameter D1s of the first side surface of the first spacer element, and the effective focal length f1 of the first lens may satisfy: 1.05 < (d1s + D1s) / f1 < 2.2. By satisfying this conditional expression, controlling the ratio of the sum of the inner and outer diameters of the first side surface (the high-beam surface) of the first spacer element to the effective focal length of the first lens within a reasonable range is conducive to reducing the generation of stray light in the system and improving the imaging quality of the system on the basis of ensuring its processability; further, by providing the first spacer element and utilizing the buffering characteristics of the material of the first spacer element, it is possible to prevent the reflective polarizing element and the quarter-wave plate from directly contacting the hard plastic, thereby improving the anti-vibration and drop reliability of the lens.

[0076] A second aspect of the present application provides a visual system, which includes a lens barrel and a four-lens group and a spacer element group assembled in the lens barrel. The four-lens group includes, in order from the first side to the second side along the optical axis: a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partially reflective element BS, a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4. The spacer element group may include one or more of a first spacer element, a second spacer element, and a third spacer element. The first spacer element may be located between the first lens and the second lens and abut against the second side surface of the first lens. The second spacer element may be located between the second lens and the third lens and abut against the second side surface of the second lens. The third spacer element may be located between the third lens and the fourth lens and abut against the second side surface of the third lens.

[0077] In an exemplary embodiment, the first lens E1 may have a positive optical power. The first side surface of the first lens E1 may be convex, and the second side surface may be convex or concave. The second lens E2 may have a negative optical power. The first side surface of the second lens E2 may be flat, and the second side surface may be concave. The first quarter-wave plate QWP1 may be disposed on the first side surface (the surface closer to the human eye) of the second lens E1 and at least partially adhered to the first side surface of the second lens E1. The reflective polarizing element RP may be disposed on the first side surface (the surface closer to the human eye) of the first quarter-wave plate QWP1 and at least partially adhered to the first side surface of the first quarter-wave plate QWP1. The third lens E3 may have a positive or negative optical power. The first side surface of the third lens E3 may be convex or concave, and the second side surface may be convex. The partial reflection element BS may be disposed on the second side surface of the third lens E3 and at least partially adhered to the second side surface of the third lens E3. The fourth lens E4 may have a positive or negative optical power. The first side surface of the fourth lens E4 may be flat, and the second side surface may be concave or convex. The polarizer LP may be disposed on the first side surface (the surface closer to the human eye) of the fourth lens E4 and at least partially adhered to the first side surface of the fourth lens E4. The second quarter-wave plate QWP2 may be disposed on the first side surface (the surface closer to the human eye) of the polarizer LP and at least partially adhered to the first side surface of the polarizer LP.

[0078] In an exemplary embodiment, the interval EP01 along the optical axis from the first side surface of the lens barrel to the first side surface of the first spacer element and the central thickness CT1 of the first lens on the optical axis may satisfy: 1.0 < EP01 / CT1 < 1.7; the inner diameter d1s of the first side surface of the first spacer element, the outer diameter D1s of the first side surface of the first spacer element, and the effective focal length f1 of the first lens may satisfy: 1.05 < (d1s + D1s) / f1 < 2.2. By satisfying the conditional expressions 1.0 < EP01 / CT1 < 1.7 and 1.05 < (d1s + D1s) / f1 < 2.2, and reasonably controlling EP01 / CT1 and (d1s + D1s) / f1 within a reasonable range, on the one hand, the edge thickness and central thickness of the first lens are at a reasonable level, which is beneficial to improving the molding stability of the first lens; at the same time, under the condition of satisfying the processability of the first lens, it is beneficial to improve the light beam convergence ability of the first lens, thereby improving the imaging quality and clarity and enhancing the visual experience; on the other hand, by controlling the ratio of the sum of the inner and outer diameters of the first side surface (the far-light surface) of the first spacer element to the effective focal length of the first lens within a reasonable range, it is beneficial to reduce the generation of stray light in the system and improve the system imaging quality on the basis of ensuring its processability; further, by providing the first spacer element and utilizing the buffering characteristics of the material of the first spacer element, it is possible to avoid direct contact between the reflective polarizing element and the quarter-wave plate and the hard plastic, and improve the anti-vibration and drop reliability of the lens.

[0079] In an embodiment of the present application, the visual system may further include a diaphragm STO disposed on the side close to the human eye. The diaphragm STO may be disposed, for example, on the first side of the first lens E1.

[0080] In an embodiment of the present application, at least one of the surfaces of each of the first lens to the fourth lens is an aspherical surface. The aspherical lens has better curvature radius characteristics and has the advantages of improving distortion aberration and astigmatism aberration. By using an aspherical lens, it is possible to eliminate as much as possible the aberration that occurs during imaging, thereby improving the imaging quality.

[0081] According to the visual system of the above embodiment of the present application, a catadioptric scheme including four lenses is adopted, and by adopting a polarized catadioptric optical path method, the body height can be better compressed and the imaging quality can be improved; at the same time, by using at least one spacer element and reasonably distributing the parameters of each lens and each spacer element, it is possible to achieve at least one aspect such as reducing the stray light risk of the visual system, improving the processability, assembly stability and imaging quality of the visual system.

[0082] Those skilled in the art should understand that without departing from the technical solution claimed in the present application, the number of lenses and spacer elements constituting the visual system can be changed to obtain the various results and advantages described in this specification.

[0083] The following further describes a specific embodiment of the visual system applicable to the above embodiment with reference to the accompanying drawings.

[0084] Example 1

[0085] The following refers to Figure 2 Describe the visual system according to Embodiment 1 of the present application.

[0086] As Figure 2 shown, the visual system includes a lens barrel P0 and a four-piece lens group and a spacer element group assembled in the lens barrel P0.

[0087] Among them, the four-piece lens group includes, in order from the first side (for example, the side close to the human eye) to the second side (for example, the side close to the display) along the optical axis: a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown in the figure), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4.

[0088] The spacer element group includes a first spacer element P1, a second spacer element P2, and a third spacer element P3. The spacer element can block the excess light during the imaging process from entering the next lens, and at the same time make the lens and the lens barrel better bear against each other, enhancing the structural stability of the visual system.

[0089] The visual system may further include a diaphragm STO disposed near the human eye side. The diaphragm STO may be disposed on the first side of the first lens E1.

[0090] In this embodiment, the first lens E1 has a positive optical power, its first side is convex, and its second side is convex. The second lens E2 has a negative optical power, its first side is flat, and its second side is concave. A first quarter-wave plate QWP1 and a reflective polarizing element RP are sequentially attached to the first side of the second lens E2. The third lens E3 has a positive optical power, its first side is convex, and its second side is convex. A partial reflection element BS is attached to the second side of the third lens E3. The fourth lens E4 has a negative optical power, its first side is flat, and its second side is concave. A polarizer LP and a second quarter-wave plate QWP2 are sequentially attached to the first side of the fourth lens E4. An optical element may also be provided between the fourth lens E4 and the image plane (IMG), and the optical element may be a filter or a protective glass, etc.

[0091] Table 1 shows the basic parameter table of the visual system of Embodiment 1. Among them, the units of the radius of curvature and the thickness / distance are both millimeters (mm). The image light rays from the display screen sequentially pass through the optical surfaces of each element and finally project into the human eye.

[0092]

[0093] Table 1

[0094] In this embodiment, the first side S16 and the second side S17 of the third lens, and the second side S21 of the fourth lens E4 are all aspherical surfaces. The surface profile x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0095]

[0096] Where x is the sagitta of the distance from the vertex of the aspherical surface when the aspherical surface is along the optical axis direction at a position with a height of h; c is the paraxial curvature of the aspherical surface, c = 1 / R (that is, the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the correction coefficient of the i-th order of the aspherical surface.

[0097] Table 2 shows the high-order term coefficients A4, A6, A8, A 10 , A 12 and A 14 , A 16 , A 18 and A 20 .

[0098] Coefficient / Plane Number S16 S17 S21 A4 -7.1874E-01 1.0574E+00 -1.8584E-01 A6 7.2814E-01 3.4208E-01 -3.6156E-03 A8 2.7264E-01 -1.1471E-01 -2.2890E-04 A10 8.7554E-02 -1.6160E-01 3.2741E-04 A12 2.8686E-02 -8.2154E-02 -8.0570E-04 A14 5.9606E-03 -2.3484E-02 -3.3659E-04 A16 2.2679E-04 -3.1671E-03 -3.6592E-04 A18 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00

[0099] Table 2

[0100] Example 2

[0101] Refer to the following Figure 3 to describe the visual system according to Embodiment 2 of the present application.

[0102] As Figure 3 shown, the visual system includes a lens barrel P0 and a four-lens group and a spacer element group assembled in the lens barrel P0. Among them, the four-lens group includes, in order along the optical axis from the first side (e.g., the side close to the human eye) to the second side (e.g., the side close to the display): a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown in the figure), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4. The spacer element group includes a first spacer element P1, a second spacer element P2, and a third spacer element P3. The visual system may further include a stop STO disposed on the side close to the human eye. The stop STO may be disposed on the first side of the first lens E1.

[0103] The structure of each lens in this embodiment is the same as that of each lens in Embodiment 1, that is, the basic parameter table of the visual system in this embodiment is the same as Table 1, and the aspherical coefficient table is the same as Table 2. In addition, the spacer elements included in the spacer element group of the visual system in this embodiment are also the same as those in Embodiment 1, except that at least one of the parameters such as the maximum length L of the lens barrel, the thickness of the spacer element, the inner diameter of the spacer element, and the outer diameter of the spacer element, the interval EP01 along the optical axis from the first side surface of the lens barrel to the first side surface of the first spacer element, and the interval along the optical axis between the spacer elements is different.

[0104] Example 3

[0105] Refer to the following Figure 4 to describe the visual system according to Embodiment 3 of the present application.

[0106] As Figure 4 shown, the visual system includes a lens barrel P0 and a four-lens group and a spacer element group assembled in the lens barrel P0. Among them, the four-lens group includes, in order along the optical axis from the first side (e.g., the side close to the human eye) to the second side (e.g., the side close to the display): a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown in the figure), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4. The spacer element group includes a first spacer element P1, a second spacer element P2, and a third spacer element P3. The visual system may further include a stop STO disposed on the side close to the human eye. The stop STO may be disposed on the first side of the first lens E1.

[0107] The structures of the lenses in this embodiment are the same as those of the lenses in Embodiment 1. That is, the basic parameter table of the visual system in this embodiment is the same as Table 1, and the aspheric coefficient table is the same as Table 2. In addition, the spacer elements included in the spacer element group of the visual system in this embodiment are also the same as those in Embodiment 1. The difference lies only in that at least one of the parameters such as the maximum length L of the lens barrel, the thickness of the spacer element, the inner diameter of the spacer element, and the outer diameter of the spacer element, the interval EP01 along the optical axis from the first side surface of the lens barrel to the first side surface of the first spacer element, and the interval along the optical axis between the spacer elements is different.

[0108] Figure 5A The axial chromatic aberration curves of the visual systems of Embodiments 1, 2, and 3 are shown, which represent the deviation of the convergence points of light rays of different wavelengths after passing through the visual system. Figure 5B The astigmatism curves of the visual systems of Embodiments 1, 2, and 3 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field angles. Figure 5C The distortion curves of the visual systems of Embodiments 1, 2, and 3 are shown, which represent the distortion magnitude values corresponding to different field angles. According to Figures 5A to 5C It can be seen that the visual systems given in Embodiments 1, 2, and 3 can achieve good imaging quality.

[0109] Figure 6 The MTF curves of the visual systems of Embodiments 1, 2, and 3 are shown. From Figure 6 it can be seen that the visual systems of Embodiments 1, 2, and 3 have good contrast within a spatial frequency of 30 lp / mm and the imaging is clear.

[0110] Example 4

[0111] The following refers to Figure 7 Describe the visual system according to Embodiment 4 of the present application.

[0112] As Figure 7 shown, the visual system includes a lens barrel P0 and a four-lens group and a spacer element group assembled in the lens barrel P0. Among them, the four-lens group includes, in order from the first side (for example, the side close to the human eye) to the second side (for example, the side close to the display) along the optical axis: a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown in the figure), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4. The spacer element group includes a first spacer element P1, a second spacer element P2, and a third spacer element P3. The visual system may also include a diaphragm STO disposed on the side close to the human eye. The diaphragm STO may be disposed on the first side of the first lens E1.

[0113] In this embodiment, the first lens E1 has a positive optical power. Its first side is convex and its second side is concave. The second lens E2 has a negative optical power. Its first side is flat and its second side is concave. A first quarter-wave plate QWP1 and a reflective polarizing element RP are successively attached to the first side of the second lens E2. The third lens E3 has a positive optical power. Its first side is convex and its second side is convex. A partial reflection element BS is attached to the second side of the third lens E3. The fourth lens E4 has a negative positive optical power. Its first side is flat and its second side is convex. A polarizer LP and a second quarter-wave plate QWP2 are successively attached to the first side of the fourth lens E4. An optical element may also be provided between the fourth lens E4 and the image plane (IMG), and the optical element may be a filter or a protective glass, etc.

[0114] Table 3 shows the basic parameter table of the visual system of Embodiment 4, where the units of the radius of curvature and the thickness / distance are both millimeters (mm).

[0115]

[0116] Table 3

[0117] In this embodiment, the first side S16 and the second side S17 of the third lens, and the second side S21 of the fourth lens E4 are all aspherical surfaces. The surface profile x of each aspherical lens can be defined by, but is not limited to, the formula (1) given in the foregoing Embodiment 1.

[0118] Table 4 shows the higher-order term coefficients A4, A6, A8, A 10 , A 12 and A 14 , A 16 , A 18 and A 20 that can be used for the aspherical surfaces S16, S17, S21 in Embodiment 4.

[0119]

[0120]

[0121] Table 4

[0122] Example 5

[0123] The following refers to Figure 8 to describe the visual system according to Embodiment 5 of the present application.

[0124] As Figure 8As shown, the visual system includes a lens barrel P0, a four-piece lens group, and a spacer element group assembled within the lens barrel P0. Among them, the four-piece lens group sequentially includes, along the optical axis from the first side (e.g., the side close to the human eye) to the second side (e.g., the side close to the display): a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown in the figure), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4. The spacer element group includes a first spacer element P1, a second spacer element P2, and a third spacer element P3. The visual system may further include a stop STO disposed on the side close to the human eye. The stop STO may be disposed on the first side of the first lens E1.

[0125] The structures of the lenses in this embodiment are the same as those of the lenses in Embodiment 4. That is, the basic parameter table of the visual system in this embodiment is the same as Table 3, and the aspheric coefficient table is the same as Table 4. Additionally, the spacer elements included in the spacer element group of the visual systems in this embodiment and Embodiment 4 are also the same. The difference lies only in that at least one of the parameters such as the maximum length L of the lens barrel, the thickness of the spacer element, the inner diameter of the spacer element, and the outer diameter of the spacer element, the distance EP01 along the optical axis from the first side surface of the lens barrel to the first side surface of the first spacer element, and the distance between the spacer elements along the optical axis is different.

[0126] Example 6

[0127] The following refers to Figure 9 Describe the visual system according to Embodiment 6 of the present application.

[0128] As Figure 9 As shown, the visual system includes a lens barrel P0, a four-piece lens group, and a spacer element group assembled within the lens barrel P0. Among them, the four-piece lens group sequentially includes, along the optical axis from the first side (e.g., the side close to the human eye) to the second side (e.g., the side close to the display): a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown in the figure), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4. The spacer element group includes a first spacer element P1, a second spacer element P2, and a third spacer element P3. The visual system may further include a stop STO disposed on the side close to the human eye. The stop STO may be disposed on the first side of the first lens E1.

[0129] The structures of the lenses in this embodiment are the same as those of the lenses in Embodiment 4. That is, the basic parameter table of the visual system in this embodiment is the same as Table 3, and the aspheric coefficient table is the same as Table 4. In addition, the spacer elements included in the spacer element group of the visual systems in this embodiment and Embodiment 4 are also the same. The difference lies only in that at least one of the parameters such as the maximum length L of the lens barrel, the thickness of the spacer element, the inner diameter of the spacer element, the outer diameter of the spacer element, the interval EP01 along the optical axis from the first side surface of the lens barrel to the first side surface of the first spacer element, and the interval along the optical axis between the spacer elements is different.

[0130] Figure 10A The axial chromatic aberration curves of the visual systems of Embodiments 4, 5, and 6 are shown, which represent the deviation of the convergence points of light rays of different wavelengths after passing through the visual system. Figure 10B The astigmatism curves of the visual systems of Embodiments 4, 5, and 6 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field angles. Figure 10C The distortion curves of the visual systems of Embodiments 4, 5, and 6 are shown, which represent the distortion magnitude values corresponding to different field angles. According to Figures 10A to 10C it can be seen that the visual systems given in Embodiments 4, 5, and 6 can achieve good imaging quality.

[0131] Figure 11 The MTF curves of the visual systems of Embodiments 4, 5, and 6 are shown. From Figure 11 it can be seen that the visual systems of Embodiments 4, 5, and 6 have good contrast within a spatial frequency of 30 lp / mm and clear imaging.

[0132] Example 7

[0133] The following refers to Figure 12 to describe the visual system according to Embodiment 7 of the present application.

[0134] As Figure 12 shown, the visual system includes a lens barrel P0 and a four-lens group and a spacer element group assembled in the lens barrel P0. Among them, the four-lens group includes, in order along the optical axis from the first side (e.g., the side close to the human eye) to the second side (e.g., the side close to the display): a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown in the figure), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4. The spacer element group includes a first spacer element P1, a second spacer element P2, and a third spacer element P3. The visual system may further include a diaphragm STO disposed on the side close to the human eye. The diaphragm STO may be disposed on the first side of the first lens E1.

[0135] In this embodiment, the first lens E1 has a positive optical power. Its first side is convex and its second side is concave. The second lens E2 has a negative optical power. Its first side is flat and its second side is concave. A first quarter-wave plate QWP1 and a reflective polarizing element RP are successively attached to the first side of the second lens E2. The third lens E3 has a negative optical power. Its first side is concave and its second side is convex. A partial reflection element BS is attached to the second side of the third lens E3. The fourth lens E4 has a positive-negative optical power. Its first side is flat and its second side is convex. A polarizer LP and a second quarter-wave plate QWP2 are successively attached to the first side of the fourth lens E4. An optical element may also be provided between the fourth lens E4 and the image plane (IMG), and the optical element may be a filter or a protective glass, etc.

[0136] Table 5 shows the basic parameter table of the visual system of Embodiment 7, where the units of the radius of curvature and the thickness / distance are both millimeters (mm).

[0137]

[0138]

[0139] Table 5

[0140] In this embodiment, the first side S16 and the second side S17 of the third lens, and the second side S21 of the fourth lens E4 are all aspherical surfaces. The surface profile x of each aspherical lens can be defined by, but not limited to, the formula (1) given in the foregoing Embodiment 1.

[0141] Table 6 shows the higher-order term coefficients A4, A6, A8, A 10 , A 12 and A 14 , A 16 , A 18 and A 20 .

[0142] Coefficient / Plane Number S16 S17 S21 A4 -2.6123E-02 8.6423E-01 -6.9149E-02 A6 1.5122E-01 3.7529E-01 2.4710E-02 A8 -1.8531E-01 4.6176E-02 -2.7986E-03 A10 -9.4805E-02 -1.6842E-02 -2.4106E-04 A12 -4.0745E-02 -1.9169E-02 9.0018E-04 A14 -1.2081E-02 -7.7663E-03 -7.1260E-04 A16 -1.9036E-03 -1.4327E-03 6.8650E-05 A18 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00

[0143] Table 6

[0144] Example 8

[0145] The following refers to Figure 13 to describe the visual system according to Embodiment 8 of the present application.

[0146] As Figure 13As shown, the visual system includes a lens barrel P0, a four-piece lens group, and a spacer element group assembled within the lens barrel P0. Among them, the four-piece lens group includes, in sequence along the optical axis from the first side (e.g., the side close to the human eye) to the second side (e.g., the side close to the display): a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown in the figure), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4. The spacer element group includes a first spacer element P1, a second spacer element P2, and a third spacer element P3. The visual system may further include a stop STO disposed on the side close to the human eye. The stop STO may be disposed on the first side of the first lens E1.

[0147] The structures of the lenses in this embodiment are the same as those of the lenses in Embodiment 7. That is, the basic parameter table of the visual system in this embodiment is the same as Table 5, and the aspheric coefficient table is the same as Table 6. Additionally, the spacer elements included in the spacer element group of the visual systems in this embodiment and Embodiment 7 are also the same. The difference lies only in that at least one of the parameters such as the maximum length L of the lens barrel, the thickness of the spacer element, the inner diameter of the spacer element, and the outer diameter of the spacer element, the interval EP01 along the optical axis from the first side surface of the lens barrel to the first side surface of the first spacer element, and the interval between the spacer elements along the optical axis is different.

[0148] Example 9

[0149] The following refers to Figure 14 Describe the visual system according to Embodiment 9 of the present application.

[0150] As Figure 14 As shown, the visual system includes a lens barrel P0, a four-piece lens group, and a spacer element group assembled within the lens barrel P0. Among them, the four-piece lens group includes, in sequence along the optical axis from the first side (e.g., the side close to the human eye) to the second side (e.g., the side close to the display): a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown in the figure), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4. The spacer element group includes a first spacer element P1, a second spacer element P2, and a third spacer element P3. The visual system may further include a stop STO disposed on the side close to the human eye. The stop STO may be disposed on the first side of the first lens E1.

[0151] The structures of the lenses in this embodiment are the same as those of the lenses in Embodiment 7, that is, the basic parameter table of the visual system in this embodiment is the same as Table 5, and the aspheric coefficient table is the same as Table 6. In addition, the spacer elements included in the spacer element group of the visual systems in this embodiment and Embodiment 7 are also the same. The difference lies only in that at least one of the parameters such as the maximum length L of the lens barrel, the thickness of the spacer element, the inner diameter of the spacer element, and the outer diameter of the spacer element, the distance EP01 along the optical axis from the first side surface of the lens barrel to the first side surface of the first spacer element, and the distance along the optical axis between the spacer elements is different.

[0152] Figure 15A The axial chromatic aberration curves of the visual systems of Embodiments 7, 8, and 9 are shown, which represent the deviation of the focusing points of light rays of different wavelengths after passing through the visual system. Figure 15B The astigmatism curves of the visual systems of Embodiments 7, 8, and 9 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field angles. Figure 15C The distortion curves of the visual systems of Embodiments 7, 8, and 9 are shown, which represent the distortion magnitude values corresponding to different field angles. According to Figures 15A to 15C it can be seen that the visual systems given in Embodiments 7, 8, and 9 can achieve good imaging quality.

[0153] Figure 16 The MTF curves of the visual systems of Embodiments 7, 8, and 9 are shown. From Figure 16 it can be seen that the visual systems of Embodiments 7, 8, and 9 have good contrast within a spatial frequency of 30 lp / mm and clear imaging.

[0154] Table 7 shows some optical parameters of the visual systems of the embodiments in Embodiments 1-9, such as the entrance pupil diameter EPD of the visual system, the distance TD on the optical axis from the first side surface of the first lens to the second side surface of the fourth lens, the effective focal length f of the visual system, and the effective focal lengths and combined focal lengths of each lens and other related parameters. The unit of each optical parameter is millimeter (mm).

[0155] Parameter / Example 1 2 3 4 5 6 7 8 9 f (mm) 42.00 42.00 42.00 42.00 42.00 42.00 42.00 42.00 42.00 f1 (mm) 30.25 30.25 30.25 54.54 54.54 54.54 51.08 51.08 51.08 f2 (mm) -43.96 -43.96 -43.96 -115.25 -115.25 -115.25 -306.52 -306.52 -306.52 f3 (mm) 69.52 69.52 69.52 145.02 145.02 145.02 -797.62 -797.62 -797.62 f4 (mm) -120.79 -120.79 -120.79 220.00 220.00 220.00 51.91 51.91 51.91 fz1 (mm) -43.96 -43.96 -43.96 -115.25 -115.25 -115.25 -306.52 -306.52 -306.52 fz2 (mm) -120.79 -120.79 -120.79 220.00 220.00 220.00 51.91 51.91 51.91

[0156] Table 7

[0157] Table 8 shows the values of some parameters of the embodiments in Embodiments 1-9, such as the values of parameters d1s, d1m, D1s, d2s, d2m, D2s, D2m, d3s, d3m,..., D0s, D0m, EP01, EP12, EP23, CP1, CP2, CP3, L, etc. Among them, the above parameters can be measured according to the Figure 1 annotation method shown, and the units of the parameters listed in Table 8 are all mm.

[0158] Parameter / Example 1 2 3 4 5 6 7 8 9 d1s 26.965 26.425 26.965 26.184 27.036 26.271 27.014 27.193 27.193 d1m 26.965 26.425 26.965 26.184 27.036 26.271 27.014 27.193 27.193 D1s 34.126 33.126 37.434 35.153 33.153 33.553 36.063 34.128 35.117 D1m 34.126 33.126 37.434 35.153 33.153 33.553 36.063 34.128 35.117 d2s 22.502 21.616 22.973 28.931 27.060 25.063 28.578 28.578 26.504 d2m 22.502 21.616 22.973 25.692 25.193 25.063 24.619 26.025 26.504 D2s 30.680 29.951 35.834 32.153 30.153 32.553 33.470 32.788 34.117 D2m 30.680 29.951 35.834 29.443 28.018 32.553 30.678 30.648 34.117 d3s 16.465 14.081 14.876 14.333 15.960 20.269 14.445 14.447 16.209 d3m 16.465 14.081 14.876 14.333 15.960 20.269 14.445 14.447 16.209 D3s 27.234 26.124 34.234 31.153 29.153 30.153 32.310 30.058 32.117 D3m 27.234 26.124 34.234 31.153 29.153 30.153 32.310 30.058 32.117 d0s 37.209 36.209 40.517 38.236 36.236 36.636 40.036 37.221 37.215 d0m 16.520 16.520 18.176 16.520 16.520 17.411 16.962 16.962 16.827 D0s 39.690 38.690 42.997 40.716 38.716 39.116 42.516 38.640 39.695 D0m 31.184 24.891 38.184 33.852 27.705 33.852 37.512 24.608 35.207 EP01 8.324 10.393 8.044 8.003 6.989 8.021 10.333 8.916 7.822 CP1 0.105 0.105 0.068 0.068 0.068 0.050 0.068 0.068 0.068 EP12 8.374 8.128 8.374 4.415 4.415 4.415 1.870 2.445 1.870 CP2 0.105 0.105 0.105 5.457 5.457 0.105 5.974 6.553 0.105 EP23 6.104 6.349 6.104 6.645 6.608 11.961 6.981 5.789 12.813 CP3 0.105 0.105 0.105 0.068 0.105 0.105 0.068 0.105 0.105 L 28.549 30.618 28.231 28.669 27.655 28.669 29.307 27.890 26.796

[0159] Table 8 In summary, in Examples 1 to 9, the visual system satisfies each conditional expression shown in Table 9 below.

[0160]

[0161] Table 9

[0162] The above description is only a preferred embodiment of the present application and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the utility model involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) having similar functions disclosed in the present application.

Claims

1. Visual system, characterized in that, It includes a lens barrel, a lens group and a spacer element group assembled in the lens barrel. The lens group includes, in order from the first side to the second side along the optical axis: a first lens with a positive optical power, a reflective polarizing element, a first quarter-wave plate, a second lens with a negative optical power, a third lens with an optical power, a partial reflection element, a second quarter-wave plate, a polarizer, and a fourth lens with an optical power. The spacer element group includes: a first spacer element located between the first lens and the second lens and abutting against the second side surface of the first lens, a second spacer element located between the second lens and the third lens and abutting against the second side surface of the second lens, and a third spacer element located between the third lens and the fourth lens and abutting against the second side surface of the third lens. Among them, the number of lenses with optical power in the lens group is four. The interval EP01 along the optical axis from the first side surface of the lens barrel to the first side surface of the first spacer element and the central thickness CT1 of the first lens on the optical axis satisfy: 1.0 < EP01 / CT1 < 1.

7. The inner diameter d0s of the first side surface of the lens barrel and the curvature radius R1 of the first side surface of the first lens satisfy: 1.75 < d0s / R1 < 2.

3.

2. The visual system according to claim 1, wherein, The interval EP12 along the optical axis from the second side surface of the first spacer element to the first side surface of the second spacer element, the central thickness CT2 of the second lens on the optical axis, and the axial distance T23 from the second side surface of the second lens to the first side surface of the third lens satisfy: 0.2 < EP12 / (CT2 + T23) < 1.

2.

3. The visual system according to claim 1, wherein The outer diameter D1m of the second side surface of the first spacer element and the outer diameter D2m of the second side surface of the second spacer element satisfy: 1.0 < D1m / D2m < 1.

2.

4. The visual system according to claim 1, characterized in that, The inner diameter d2s of the first side surface of the second spacer element, the inner diameter d2m of the second side surface of the second spacer element, the curvature radius R4 of the second side surface of the second lens, and the curvature radius R5 of the first side surface of the third lens satisfy: 0.2 < (d2s + d2m) / (R4 + R5) < 0.

65.

5. The visual system according to claim 1, characterized in that, The inner diameter d3s of the first side surface of the third spacer element and the central thickness CT3 of the third lens on the optical axis satisfy: 2.0 < d3s / CT3 < 2.

95.

6. The visual system according to claim 1, characterized in that, The inner diameter d0m of the second side surface of the lens barrel, the central thickness CTQ2 of the second quarter-wave plate on the optical axis, the central thickness CTL of the polarizer on the optical axis, and the central thickness CT4 of the fourth lens on the optical axis satisfy: 6.29 ≤ d0m / (CTQ2 + CTL + CT4) < 9.

9.

7. The visual system according to claim 1, characterized in that, The inner diameter d1m of the second side surface of the first spacer element and the combined focal length fz1 of the reflective polarizing element, the first quarter-wave plate, and the second lens satisfy: -0.65 < d1m / fz1 < -0.

05.

8. The visual system according to claim 1, wherein The inner diameter d3m of the second side surface of the third spacer element, the outer diameter D3m of the second side surface of the third spacer element, and the combined focal length fz2 of the second quarter-wave plate, the polarizer, and the fourth lens satisfy: 0.2 < (d3m + D3m) / |fz2| ≤ 0.

93.

9. The visual system according to claim 1, characterized in that, The outer diameter D3s of the first side surface of the third spacer element and the curvature radius R6 of the second side surface of the third lens satisfy: -0.3 < D3s / R6 < 0.

10. The visual system according to claim 1, characterized in that, The outer diameter D0s of the first side surface of the lens barrel, the outer diameter D0m of the second side surface of the lens barrel, and the interval L along the optical axis from the first side surface of the lens barrel to the second side surface of the lens barrel satisfy: 0.15 < (D0s - D0m) / L < 0.

55.

11. The visual system according to any one of claims 1-10, characterized in that, The maximum thickness CP2 of the second spacer element, the interval EP23 along the optical axis from the second side surface of the second spacer element to the first side surface of the third spacer element, the central thickness CT3 of the third lens on the optical axis, and the on-axis distance T34 from the second side surface of the third lens to the first side surface of the fourth lens satisfy: 0.8 < (CP2 + EP23) / (CT3 + T34) ≤ 2.

13.

12. The visual system according to any one of claims 1-10, characterized in that, The outer diameter D2s of the first side surface of the second spacer element and the effective focal length f2 of the second lens satisfy: -0.85 < D2s / f2 < -0.

1.

13. The visual system according to any one of claims 1 to 10, characterized in that, The maximum thickness CP1 of the first spacer element and the maximum thickness CP3 of the third spacer element satisfy: 0.48 ≤ CP1 / CP3 < 1.

05.

14. The visual system according to any one of claims 1 to 10, characterized in that, The inner diameter d1s of the first side surface of the first spacer element, the outer diameter D1s of the first side surface of the first spacer element, and the effective focal length f1 of the first lens satisfy: 1.05 < (d1s + D1s) / f1 ≤ 2.

13.

15. The visual system according to any one of claims 1-10, characterized in that The first side surface of the first lens is convex, and the second side surface is convex or concave; The first side surface of the second lens is flat, and the second side surface is concave; The third lens has a positive or negative optical power, its first side surface is convex or concave, and the second side surface is convex; The fourth lens has a positive or negative optical power, its first side surface is flat, and the second side surface is convex or concave.

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