Visual system

Abstract

The utility model discloses a visual system. The visual system comprises a lens cone, a spacing element group and an optical element group, wherein the spacing element group and the optical element group are assembled in the lens cone. The optical element group comprises a first lens with positive focal power, a reflective polarization element, a first quarter-wave plate, a second lens with positive focal power, a third lens with negative focal power, a partial reflection element and a fourth lens with focal power which are sequentially arranged from the first side to the second side along the optical axis; a second quarter-wave plate; and a polarizer. The spacing element group comprises a first spacing element, a second spacing element and a third spacing element. Wherein the maximum thickness CP2 of the second spacing element and the maximum thickness CP3 of the third spacing element meet the condition that CP2 is equal to CP3; the center thickness CTR of the reflective polarizing element on the optical axis, the center thickness CTQ1 of the first quarter-wave plate on the optical axis, the on-axis distance T12 from the second side face of the first lens to the first side face of the second lens and the maximum thickness CP1 of the first spacing element satisfy 1.2 lt; (CTR + CTQ1 + T12) / CP1lt; 2.1.

Description

Technical Field

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

[0002] With the introduction of the concept of the metaverse, virtual reality and augmented reality technologies for human-computer interaction have ushered in a second opportunity for development. As an important entrance to human-computer interaction, the visual system plays a key role in it. Early visual systems mainly used aspherical lenses or Fresnel lenses, which had a long body length and the user's center of gravity was forward when worn, thus affecting the user's experience.

[0003] The catadioptric optical system is a major innovation in the visual system itself. It reserves space for the overall design of virtual reality devices or augmented reality devices and has become a mainstream trend in research and development. The catadioptric optical system shortens the length of the visual system by bending the optical path, thereby moving the center of gravity of the virtual reality device or augmented reality device backward and improving the user experience. However, the existing catadioptric optical system usually uses two lenses, which will cause the picture of the catadioptric optical system to be blurry and the image quality to be poor. Utility Model Content

[0004] One aspect of the present application provides such a visual system, which includes a lens barrel and a spacing element group and an optical element group assembled in the lens barrel. The optical element group includes a first lens with positive optical power, a reflective polarizing element, a first quarter wave plate, a second lens with positive optical power, a third lens with negative optical power, a partial reflection element, a fourth lens with optical power, a second quarter wave plate and a polarizer in sequence along the optical axis from the first side to the second side; wherein the first side surface of the first lens is a convex surface and the second side surface is a plane; the second side surface of the second lens is a convex surface; the first side surface of the third lens is a concave surface; and the second side surface of the fourth lens is a plane. The spacing element group includes a first spacing element, a second spacing element and a third spacing element, the first spacing element is placed on the second side surface of the first lens and contacts with the second side surface of the first lens, the second spacing element is placed on the second side surface of the second lens and contacts with the second side surface of the second lens, and the third spacing element is placed on the second side surface of the third lens and contacts with the second side surface of the third lens. Among them, the maximum thickness CP2 of the second spacing element and the maximum thickness CP3 of the third spacing element satisfy: CP2=CP3; the center thickness CTR of the reflective polarizing element on the optical axis, the center thickness CTQ1 of the first quarter wave plate on the optical axis, the axial distance T12 from the second side surface of the first lens to the first side surface of the second lens and the maximum thickness CP1 of the first spacing element satisfy: 1.2<(CTR+CTQ1+T12) / CP1<2.1.

[0005] According to an exemplary embodiment of the present application, the combined focal length fz2 of the fourth lens, the second quarter-wave plate, and the polarizer, the inner diameter d0m of the second end face of the lens barrel, and the outer diameter D0m of the second end face of the lens barrel satisfy: 0.4 < |fz2| / (d0m + D0m) < 2.4.

[0006] According to an exemplary embodiment of the present application, the on-axis distance TD from the first side face of the first lens to the second side face of the fourth lens and the distance EP23 between the second spacer element and the third spacer element along the optical axis satisfy: 2.6 < TD / EP23 < 3.2.

[0007] According to an exemplary embodiment of the present application, the inner diameter d0s of the first end face of the lens barrel and the curvature radius R1 of the first side face of the first lens satisfy: 1.5 < d0s / R1 < 1.7.

[0008] According to an exemplary embodiment of the present application, the outer diameter D0s of the first end face of the lens barrel and the distance L along the optical axis between the first end face of the lens barrel and the second end face of the lens barrel satisfy: 1.5 < D0s / L < 1.7.

[0009] According to an exemplary embodiment of the present application, the effective focal length f1 of the first lens, the inner diameter d0s of the first end face of the lens barrel, and the inner diameter d0m of the second end face of the lens barrel satisfy: 2.7 < f1 / (d0s - d0m) < 3.0.

[0010] According to an exemplary embodiment of the present application, the combined focal length fz1 of the first lens, the reflective polarizing element, and the first quarter-wave plate, the outer diameter D1s of the first side face of the first spacer element, the effective focal length f2 of the second lens, and the outer diameter D1m of the second side face of the first spacer element satisfy: 1.9 < (fz1 / D1s) × (f2 / D1m) < 2.8.

[0011] According to an exemplary embodiment of the present application, the inner diameter d2s of the first side face of the second spacer element and the central thickness CT2 of the second lens on the optical axis satisfy: 3.8 ≤ d2s / CT2 ≤ 4.15.

[0012] According to an exemplary embodiment of the present application, the effective focal length f3 of the third lens, the inner diameter d2m of the second side face of the second spacer element, and the outer diameter D2m of the second side face of the second spacer element satisfy: -1.3 < f3 / (d2m + D2m) < -0.65.

[0013] According to an exemplary embodiment of the present application, the outer diameter D2s of the first side face of the second spacer element, the curvature radius R4 of the second side face of the second lens, and the curvature radius R5 of the first side face of the third lens satisfy: 0.3 < D2s / |R4 + R5| < 0.8.

[0014] According to an exemplary embodiment of the present application, the inner diameter d3s of the first side surface of the third spacer element, the inner diameter d3m of the second side surface of the third spacer element, and the central thickness CT3 of the third lens on the optical axis satisfy: 6.6 < (d3s + d3m) / CT3 < 7.8.

[0015] According to an exemplary embodiment of the present application, the outer diameter D3s of the first side surface of the third spacer element, the outer diameter D3m of the second side surface of the third spacer element, and the total effective focal length f of the visual system satisfy: 1.4 < (D3s + D3m) / f < 1.6.

[0016] According to an exemplary embodiment of the present application, the total effective focal length f of the visual system, the distance EP12 between the first spacer element and the second spacer element along the optical axis, and the maximum thickness CP2 of the second spacer element satisfy: 8.3 < f / (EP12 + CP2) < 9.8.

[0017] According to an exemplary embodiment of the present application, the distance EP01 between the first side end surface of the lens barrel and the first spacer element along the optical axis, the inner diameter d1m of the second side surface of the first spacer element, and the inner diameter d1s of the first side surface of the first spacer element satisfy: 1.2 < EP01 / (d1m - d1s) < 3.4.

[0018] According to an exemplary embodiment of the present application, the distance EP23 between the second spacer element and the third spacer element along the optical axis, the distance EP01 between the first side end surface of the lens barrel and the first spacer element along the optical axis, and the distance EP12 between the first spacer element and the second spacer element along the optical axis satisfy: 1.1 < EP23 / (EP01 + EP12) < 1.6.

[0019] The visual system provided by the present application uses four lenses. By balancing the maximum thickness of the second spacer element and the maximum thickness of the third spacer element, and coordinating the relationship between the central thickness of the reflective polarizing element on the optical axis, the central thickness of the first quarter-wave plate on the optical axis, the axial distance from the second side surface of the first lens to the first side surface of the second lens, and the maximum thickness of the first spacer element, it is beneficial to realize the compact design of the visual system, reduce the volume and weight of the visual system, and improve the wearing convenience; at the same time, it is also beneficial to reasonably distribute the central thicknesses of the reflective polarizing element, the first quarter-wave plate, and the first lens, ensure good processability of the first quarter-wave plate, the reflective polarizing element, and the first lens, and reduce the assembly difficulty of the visual system. Description of the Drawings

[0020] Other features, objects, and advantages of the present application will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings. Among them:

[0021] Figure 1 Shows a parameter annotation diagram of the visual system according to an embodiment of the present application;

[0022] Figure 2 Shows a schematic structural diagram of the visual system according to Embodiment 1 of the present application;

[0023] Figure 3 Shows a schematic structural diagram of the visual system according to Embodiment 2 of the present application;

[0024] Figure 4 Shows a schematic structural diagram of the visual system according to Embodiment 3 of the present application;

[0025] Figure 5A 、 Figure 5B 、 Figure 5C 、 Figure 5D Respectively show the axial chromatic aberration curve, astigmatism curve, distortion curve, and modulation transfer function curve of the visual system according to Embodiments 1, 2, and 3 of the present application;

[0026] Figure 6 Shows a schematic structural diagram of the visual system according to Embodiment 4 of the present application;

[0027] Figure 7 Shows a schematic structural diagram of the visual system according to Embodiment 5 of the present application;

[0028] Figure 8 Shows a schematic structural diagram of the visual system according to Embodiment 6 of the present application;

[0029] Figure 9A 、 Figure 9B 、 Figure 9C 、 Figure 9D Respectively show the axial chromatic aberration curve, astigmatism curve, distortion curve, and modulation transfer function curve of the visual system according to Embodiments 4, 5, and 6 of the present application;

[0030] Figure 10 Shows a schematic structural diagram of the visual system according to Embodiment 7 of the present application;

[0031] Figure 11 Shows a schematic structural diagram of the visual system according to Embodiment 8 of the present application;

[0032] Figure 12 Shows a schematic structural diagram of the visual system according to Embodiment 9 of the present application; and

[0033] Figure 13A 、 Figure 13B 、 Figure 13C 、 Figure 13D Respectively show the axial chromatic aberration curve, astigmatism curve, distortion curve, and modulation transfer function curve of the visual system according to Embodiments 7, 8, and 9 of the present application. Detailed Embodiments

[0034] To better understand the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of 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.

[0035] It should be noted that in this specification, the expressions such as first, second, third, 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.

[0036] In the drawings, for ease of illustration, the thickness, size, and shape of the lens have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are for illustration only and are not drawn to an exact scale.

[0037] In this document, 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. The surface of each lens closest to the object being photographed is called the first side of the lens, and the surface of each lens closest to the image plane is called the second side of the lens.

[0038] It should also be understood that the terms "comprising" and / or "having", when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or their combinations. In addition, when describing the embodiments of the present application, the use of "may" means "one or more embodiments of the present application". And the term "exemplary" is intended to refer to an example or illustration.

[0039] 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.

[0040] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The following will describe the present application in detail with reference to the drawings and in combination with the embodiments.

[0041] Figure 1 It is a parameter annotation diagram according to an exemplary embodiment of the present application. Refer to Figure 1 , D0s represents the outer diameter of the first side end face of the lens barrel, D0m represents the outer diameter of the second side end face of the lens barrel, d0s represents the inner diameter of the first side end face of the lens barrel, d0m represents the inner diameter of the second side end face of the lens barrel, D1s represents the outer diameter of the first side face of the first spacer element, D1m represents the outer diameter of the second side face of the first spacer element, d1s represents the inner diameter of the first side face of the first spacer element, d1m represents the inner diameter of the second side face of the first spacer element, D2s represents the outer diameter of the first side face of the second spacer element, D2m represents the outer diameter of the second side face of the second spacer element, d2m represents the inner diameter of the second side face of the second spacer element, d2s represents the inner diameter of the first side face of the second spacer element, D3s represents the outer diameter of the first side face of the third spacer element, D3m represents the outer diameter of the second side face of the third spacer element, d3s represents the inner diameter of the first side face of the third spacer element, d3m represents the inner diameter of the second side face of the third spacer element, EP01 represents the distance along the optical axis between the first side end face of the lens barrel and the first spacer element, CP1 represents the maximum thickness of the first spacer element, EP12 represents the distance along the optical axis between the first spacer element and the second spacer element, CP2 represents the maximum thickness of the second spacer element, EP23 represents the distance along the optical axis between the second spacer element and the third spacer element, CP3 represents the maximum thickness of the third spacer element, and L represents the distance along the optical axis between the first side end face of the lens barrel and the second side end face of the lens barrel.

[0042] The first aspect of the present application provides such a visual system, which may include an optical element group. The optical element group may include a first lens, a reflective polarizing element, a first quarter-wave plate, a second lens, a third lens, a partial reflection element, a fourth lens, a second quarter-wave plate, and a polarizer arranged in sequence along the optical axis from the first side to the second side.

[0043] In an exemplary embodiment, the first lens may have a positive optical power. The second lens may have a positive optical power. The third lens may have a negative optical power. The fourth lens may have a positive optical power or a negative optical power.

[0044] In an exemplary embodiment, the first side face of the first lens may be convex, and the second side face may be flat.

[0045] In an exemplary embodiment, the second side face of the second lens may be convex.

[0046] In an exemplary embodiment, the first side face of the third lens may be concave.

[0047] In an exemplary embodiment, the second side surface of the fourth lens may be a plane.

[0048] In an exemplary embodiment, the reflective polarizing element may be disposed on the second side surface of the first lens and at least partially adhered to the second side surface of the first lens. The first quarter-wave plate may be disposed on the second side surface of the reflective polarizing element and at least partially adhered to the second side surface of the reflective polarizing element.

[0049] In an exemplary embodiment, the partial reflection element may be disposed on the second side surface of the third lens and at least partially adhered to the second side surface of the third lens. The partial reflection element has a semi-transmissive and semi-reflective effect on light. By disposing the partial reflection element on the second side surface of the third lens and combining it with the reflective polarizing element and the first quarter-wave plate, the light can be refracted and reflected multiple times, effectively reducing the body length of the visual system.

[0050] In an exemplary embodiment, the second quarter-wave plate may be disposed on the second side surface of the fourth lens and at least partially adhered to the second side surface of the fourth lens. The polarizer may be disposed on the second side surface of the second quarter-wave plate and at least partially adhered to the second side surface of the second quarter-wave plate.

[0051] In an exemplary embodiment, the visual system may further include a diaphragm, and the diaphragm may be disposed on the first side of the first lens. As an example, the diaphragm may be, for example, the pupil of the user's eye. The image light from the second side passes through the polarizer, the second quarter-wave plate, the fourth lens, the partial reflection element, the third lens, the second lens, the first quarter-wave plate, the reflective polarizing element, the first lens, etc., and is finally projected onto the user's eye on the first side after multiple refractions and reflections.

[0052] In an exemplary embodiment, the first side may be, for example, the human eye side, and the second side may be, for example, the display screen side. Correspondingly, the first side surfaces of the respective elements (such as the first lens, the second lens, the third lens, the fourth lens, the first quarter-wave plate, the second quarter-wave plate) may be referred to as the near-eye side surfaces, and the second side surfaces may be referred to as the near-screen side surfaces.

[0053] In an exemplary embodiment, an image plane may be provided on the second side of the visual system, and a display screen may be provided on the image plane. The light from the display screen sequentially passes through a polarizer, a second quarter-wave plate, a fourth lens, a third lens, a second lens, and a first quarter-wave plate, reaches a reflective polarizing element, and then forms a first reflected image light by reflection at the reflective polarizing element. The first reflected image light sequentially passes through the first quarter-wave plate, the second lens, the third lens, and reaches a partial reflection element on the second side surface of the third lens, and then forms a second reflected image light by reflection at the partial reflection element. The second reflected image light sequentially passes through the third lens, the second lens, the first quarter-wave plate, the reflective polarizing element, the first lens to the aperture, and finally projects onto the user's eyes. The visual system provided in this application folds the required optical path by a combination of light reflection and refraction without affecting the projection quality, effectively shortening the body length of the visual system.

[0054] In an exemplary embodiment, the visual system may further include a spacer element group. The spacer element group may include one or more of a first spacer element, a second spacer element, and a third spacer element. Reasonable use of the 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.

[0055] In an exemplary embodiment, the visual system may further include a lens barrel. The optical element group and the spacer element group are disposed inside the lens barrel. Among them, the end surface of the lens barrel closest to the first side is the first side end surface of the lens barrel, and the end surface of the lens barrel closest to the second side is the second side end surface of the lens barrel.

[0056] In an exemplary embodiment, the set of spacer elements may include a first spacer element, a second spacer element, and a third spacer element. The first spacer element may be disposed on the second side surface of the first lens and at least partially in contact with the second side surface of the first lens. The second spacer element may be disposed on the second side surface of the second lens and at least partially in contact with the second side surface of the second lens. The third spacer element may be disposed on the second side surface of the third lens and at least partially in contact with the second side surface of the third lens. The maximum thickness CP2 of the second spacer element and the maximum thickness CP3 of the third spacer element may satisfy: CP2 = CP3; the central thickness CTR of the reflective polarizing element on the optical axis, the central thickness CTQ1 of the first quarter-wave plate on the optical axis, the axial distance T12 from the second side surface of the first lens to the first side surface of the second lens, and the maximum thickness CP1 of the first spacer element may satisfy: 1.2 < (CTR + CTQ1 + T12) / CP1 < 2.1. By balancing the maximum thickness of the second spacer element and the maximum thickness of the third spacer element, and coordinating the relationship between the central thickness of the reflective polarizing element on the optical axis, the central thickness of the first quarter-wave plate on the optical axis, the axial distance from the second side surface of the first lens to the first side surface of the second lens, and the maximum thickness of the first spacer element, it is beneficial to achieve a compact design of the visual system, reduce the volume and weight of the visual system and the device including the visual system, and improve the wearing convenience; at the same time, it is also beneficial to reasonably distribute the central thicknesses of the reflective polarizing element, the first quarter-wave plate, and the first lens, ensure good processability of the first quarter-wave plate, the reflective polarizing element, and the first lens, and reduce the assembly difficulty of the visual system.

[0057] In an exemplary embodiment, the combined focal length fz2 of the fourth lens, the second quarter-wave plate, and the polarizer, the inner diameter d0m of the second side end surface of the lens barrel, and the outer diameter D0m of the second side end surface of the lens barrel may satisfy: 0.4 < |fz2| / (d0m + D0m) < 2.4. Reasonably configuring the relationship between the combined focal length of the fourth lens, the second quarter-wave plate, and the polarizer, the inner diameter of the second side end surface of the lens barrel, and the outer diameter of the second side end surface of the lens barrel is beneficial to increasing the field of view angle of the visual system, enabling the user to see as much display content as possible, such as virtual reality content or augmented reality content, enhancing the immersion and user experience of the visual system, and at the same time, it can also ensure that the lens barrel has sufficient bearing width during the assembly process, improving the assembly stability and assembly yield of the visual system.

[0058] In an exemplary embodiment, the spacer element group may include a second spacer element and a third spacer element. The second spacer element may be disposed on the second side surface of the second lens and at least partially in contact with the second side surface of the second lens, and the third spacer element may be disposed on the second side surface of the third lens and at least partially in contact with the second side surface of the third lens. The on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens and the distance EP23 of the second spacer element and the third spacer element along the optical axis may satisfy: 2.6 < TD / EP23 < 3.2. Reasonably configuring the ratio of the on-axis distance from the first side surface of the first lens to the second side surface of the fourth lens to the distance of the second spacer element and the third spacer element along the optical axis is beneficial to controlling the overall length of the visual system to meet the requirements of the module end and realizing the miniaturized design of the visual system; at the same time, it is also beneficial to reasonably distribute the edge thickness of the third lens and improve the processability of the third lens.

[0059] In an exemplary embodiment, the inner diameter d0s of the first side end surface of the lens barrel and the curvature radius R1 of the first side surface of the first lens may satisfy: 1.5 < d0s / R1 < 1.7. Reasonably configuring the ratio of the inner diameter of the first side end surface of the lens barrel to the curvature radius of the first side surface of the first lens is beneficial to the rapid convergence of the incident light inside the first lens, converging the light passing aperture of the visual system, and at the same time, it can also constrain the light beam, increase the field of view angle of the visual system, and improve the user experience.

[0060] In an exemplary embodiment, the outer diameter D0s of the first side end surface of the lens barrel and the distance L along the optical axis between the first side end surface of the lens barrel and the second side end surface of the lens barrel may satisfy: 1.5 < D0s / L < 1.7. By controlling the ratio of the outer diameter of the first side end surface of the lens barrel to the distance along the optical axis between the first side end surface of the lens barrel and the second side end surface of the lens barrel within a certain range, the outer dimension of the lens barrel can be constrained to meet the requirements of the module end and realize the miniaturization of the visual system.

[0061] In an exemplary embodiment, the effective focal length f1 of the first lens, the inner diameter d0s of the first side end surface of the lens barrel, and the inner diameter d0m of the second side end surface of the lens barrel may satisfy: 2.7 < f1 / (d0s - d0m) < 3.0. Reasonably configuring the relationship among the effective focal length f1 of the first lens, the inner diameter d0s of the first side end surface of the lens barrel, and the inner diameter of the second side end surface of the lens barrel is beneficial to controlling the entrance pupil diameter of the visual system on the basis of ensuring good light throughput of the visual system, making it meet ergonomics, improving the immersive experience of the visual system, and at the same time, it can also ensure that the aberration of the first lens is at a reasonable level and improve the imaging quality of the visual system.

[0062] In an exemplary embodiment, the spacer element group may include a first spacer element. The first spacer element may be disposed on the second side surface of the first lens and at least partially in contact with the second side surface of the first lens. The combined focal length fz1 of the first lens, the reflective polarizing element, and the first quarter-wave plate, the outer diameter D1s of the first side surface of the first spacer element, the effective focal length f2 of the second lens, and the outer diameter D1m of the second side surface of the first spacer element may satisfy: 1.9 < (fz1 / D1s) × (f2 / D1m) < 2.8. Reasonably configuring the relationship between the combined focal length of the first lens, the reflective polarizing element, and the first quarter-wave plate, the outer diameter of the first side surface of the first spacer element, the effective focal length of the second lens, and the outer diameter of the second side surface of the first spacer element is beneficial to controlling the polarization performance of the visual system, achieving the control of the polarization characteristics of the visual system, and balancing the imaging quality, polarization performance, and overall design complexity of the visual system, ensuring that the visual system has better overall performance. At the same time, it is also beneficial to restricting the light transmission amount of the visual system and ensuring that the field of view angle of the visual system is at a reasonable level.

[0063] In an exemplary embodiment, the spacer element group may include a second spacer element. The second spacer element may be disposed on the second side surface of the second lens and at least partially in contact with the second side surface of the second lens. The inner diameter d2s of the first side surface of the second spacer element and the central thickness CT2 of the second lens on the optical axis may satisfy: 3.8 ≤ d2s / CT2 ≤ 4.15. Reasonably configuring the ratio of the inner diameter of the first side surface of the second spacer element to the central thickness of the second lens on the optical axis is beneficial to balancing the light transmission aperture of the first side surface of the second lens and the central thickness of the second lens, improving the processability of the second lens. At the same time, it is also beneficial to enabling the second spacer element to block the internal stray light of the third lens and improving the imaging quality of the visual system.

[0064] In an exemplary embodiment, the spacer element group may include a second spacer element. The second spacer element may be disposed on the second side surface of the second lens and at least partially in contact with the second side surface of the second lens. The effective focal length f3 of the third lens, the inner diameter d2m of the second side surface of the second spacer element, and the outer diameter D2m of the second side surface of the second spacer element may satisfy: -1.3 < f3 / (d2m + D2m) < -0.65. Reasonably configuring the relationship between the effective focal length of the third lens, the inner diameter of the second side surface of the second spacer element, and the outer diameter of the second side surface of the second spacer element is beneficial to using the second spacer element to block stray light and improving the imaging quality of the visual system. At the same time, the buffer characteristics of the second spacer element can be used to reduce the assembly stress of the visual system and improve the assembly yield of the visual system.

[0065] In an exemplary embodiment, the spacer element group may include a second spacer element. The second spacer element may be disposed on the second side surface of the second lens and at least partially in contact with the second side surface of the second lens. The outer diameter D2s of the first side surface of the second spacer element, the radius of curvature R4 of the second side surface of the second lens, and the radius of curvature R5 of the first side surface of the third lens may satisfy: 0.3 < D2s / |R4 + R5| < 0.8. By reasonably configuring the relationship among the outer diameter of the first side surface of the second spacer element, the radius of curvature of the second side surface of the second lens, and the radius of curvature of the first side surface of the third lens, the overall shapes of the second lens and the third lens can be constrained, and the processability of the second lens and the third lens can be improved.

[0066] In an exemplary embodiment, the spacer element group may include a third spacer element. The third spacer element may be disposed on the second side surface of the third lens and at least partially in contact with the second side surface of the third lens. The inner diameter d3s of the first side surface of the third spacer element, the inner diameter d3m of the second side surface of the third spacer element, and the central thickness CT3 of the third lens on the optical axis may satisfy: 6.6 < (d3s + d3m) / CT3 < 7.8. By reasonably configuring the relationship among the inner diameter of the first side surface of the third spacer element, the inner diameter of the second side surface of the third spacer element, and the central thickness of the third lens on the optical axis, it is beneficial to control the assembly step difference between the second lens and the third lens, improve the assembly stability of the visual system, and at the same time, it is also beneficial to control the ratio of the outer diameter to the central thickness of the third lens within a reasonable range, thereby improving the processability of the third lens.

[0067] In an exemplary embodiment, the spacer element group may include a third spacer element. The third spacer element may be disposed on the second side surface of the third lens and at least partially in contact with the second side surface of the third lens. The outer diameter D3s of the first side surface of the third spacer element, the outer diameter D3m of the second side surface of the third spacer element, and the total effective focal length f of the visual system may satisfy: 1.4 < (D3s + D3m) / f < 1.6. By reasonably configuring the relationship among the outer diameter of the first side surface of the third spacer element, the outer diameter of the second side surface of the third spacer element, and the total effective focal length of the visual system, the total effective focal length of the visual system can be constrained, the aberration of the visual system can be at a reasonable level, and the imaging quality of the visual system can be improved. At the same time, on the basis of ensuring good processability of the third spacer element, the stray light between the third lens and the fourth lens can be effectively blocked, thereby improving the imaging quality of the visual system.

[0068] In an exemplary embodiment, the spacer element group may include a first spacer element and a second spacer element. The first spacer element may be disposed on the second side surface of the first lens and at least partially in contact with the second side surface of the first lens, and the second spacer element may be disposed on the second side surface of the second lens and at least partially in contact with the second side surface of the second lens. The total effective focal length f of the visual system, the distance EP12 between the first spacer element and the second spacer element along the optical axis, and the maximum thickness CP2 of the second spacer element may satisfy: 8.3 < f / (EP12 + CP2) < 9.8. By controlling the above conditional expression, the total effective focal length of the visual system can be constrained, the aberration of the visual system can be brought to a reasonable level, the imaging quality of the visual system can be improved, and at the same time, the edge thicknesses of the lenses between the first lens and the third lens can be reasonably distributed. On the basis of ensuring good processability of the first lens to the third lens, the assembly stability between the first lens and the third lens can be improved.

[0069] In an exemplary embodiment, the spacer element group may include a first spacer element. The first spacer element may be disposed on the second side surface of the first lens and at least partially in contact with the second side surface of the first lens. The distance EP01 between the first side end surface of the lens barrel and the first spacer element along the optical axis, the inner diameter d1m of the second side surface of the first spacer element, and the inner diameter d1s of the first side surface of the first spacer element may satisfy: 1.2 < EP01 / (d1m - d1s) < 3.4. By controlling the above conditional expression, it is beneficial to control the assembly step difference between the first lens and the second lens, improve the assembly stability and assembly yield of the visual system; at the same time, it is also beneficial to ensure that there is sufficient space for dispensing glue at the first side end of the lens barrel, and prevent the glue from overflowing to the first side end surface of the lens barrel.

[0070] In an exemplary embodiment, the spacer element group may include a first spacer element, a second spacer element, and a third spacer element. The first spacer element may be disposed on the second side surface of the first lens and at least partially in contact with the second side surface of the first lens, the second spacer element may be disposed on the second side surface of the second lens and at least partially in contact with the second side surface of the second lens, and the third spacer element may be disposed on the second side surface of the third lens and at least partially in contact with the second side surface of the third lens. The distance EP23 between the second spacer element and the third spacer element along the optical axis, the distance EP01 between the first side end surface of the lens barrel and the first spacer element along the optical axis, and the distance EP12 between the first spacer element and the second spacer element along the optical axis may satisfy: 1.1 < EP23 / (EP01 + EP12) < 1.6. By controlling the above conditional expression, it is beneficial to reasonably distribute the edge thicknesses of the first lens, the second lens, and the third lens, improve the processability of the first lens, the second lens, and the third lens, and improve the assembly stability of the visual system.

[0071] In an exemplary embodiment, the visual system may further include a protective glass for protecting the photosensitive element located on the image plane.

[0072] The visual system according to the above-described embodiment of the present application may employ multiple lenses, such as the four lenses described above. By reasonably allocating the parameters of the reflective polarizing element, the first quarter-wave plate, the second quarter-wave plate, the polarizer, each lens, the lens barrel, and each spacer element, the body length of the visual system can be reduced, and the processability, assembly stability, and imaging quality of the visual system can be improved. The visual system configured as described above has characteristics such as miniaturization and good imaging quality, and can well meet the usage requirements of various portable electronic products in the projection scenario. Moreover, the center of gravity of the visual system and the electronic device including the visual system moves backward, improving the user's wearing experience.

[0073] In an exemplary embodiment, at least one of the surfaces of each lens among the second lens to the fourth lens is an aspherical surface. The characteristic of an aspherical lens is that the curvature continuously changes from the center of the lens to the periphery of the lens. Different from a spherical lens with a constant curvature from the center of the lens to the periphery, an aspherical lens has better curvature radius characteristics and has the advantages of improving distortion aberration and astigmatism aberration. After using an aspherical lens, it is possible to eliminate as much as possible the aberration that appears during imaging, thereby improving the imaging quality.

[0074] The second aspect of the present application provides such a visual system, which may include a lens barrel and a spacer element group and an optical element group assembled in the lens barrel. The optical element group may sequentially include a first lens with a positive optical power, a reflective polarizing element, a first quarter-wave plate, a second lens with a positive optical power, a third lens with a negative optical power, a partial reflection element, a fourth lens with an optical power, a second quarter-wave plate, and a polarizer along the optical axis from the first side to the second side. Among them, the first side surface of the first lens is convex, and the second side surface is flat; the second side surface of the second lens is convex; the first side surface of the third lens is concave; the second side surface of the fourth lens is flat. The spacer element group may include a first spacer element, a second spacer element, and a third spacer element. The first spacer element may be placed on the second side surface of the first lens and in contact with the second side surface of the first lens. The second spacer element may be placed on the second side surface of the second lens and in contact with the second side surface of the second lens. The third spacer element may be placed on the second side surface of the third lens and in contact with the second side surface of the third lens.

[0075] The maximum thickness CP2 of the second spacer element and the maximum thickness CP3 of the third spacer element may satisfy: CP2 = CP3; the distance EP01 between the first side end face of the lens barrel and the first spacer element along the optical axis, the inner diameter d1m of the second side face of the first spacer element, and the inner diameter d1s of the first side face of the first spacer element may satisfy: 1.2 < EP01 / (d1m - d1s) < 3.4. The visual system provided in this application uses four lenses, and reasonably configuring the optical powers of the four lenses is beneficial to improving the imaging quality of the visual system; by balancing the maximum thickness of the second spacer element and the maximum thickness of the third spacer element, and coordinating the relationship between the distance between the first side end face of the lens barrel and the first spacer element along the optical axis, the inner diameter of the second side face of the first spacer element and the inner diameter of the first side face of the first spacer element, it is beneficial to control the assembly step difference between the first lens and the second lens, improve the assembly stability and assembly yield of the visual system; at the same time, it is also beneficial to ensure that there is sufficient dispensing space at the first side end of the lens barrel, and avoid glue overflowing to the first side end face of the lens barrel.

[0076] Those skilled in the art should understand that without departing from the technical solutions claimed in this 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.

[0077] The following further describes specific embodiments of the visual system applicable to the above embodiments with reference to the accompanying drawings.

[0078] Example 1

[0079] The following refers to Figure 2 Describe the visual system according to Embodiment 1 of this application.

[0080] As Figure 2 shown, the visual system may include a lens barrel P0 and an optical element group and a spacer element group assembled in the lens barrel P0.

[0081] The optical element group includes 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, a fourth lens E4, a second quarter-wave plate QWP2, and a polarizer LP arranged in sequence along the optical axis from the first side to the second side. An aperture STO is arranged between the first side and the first lens E1. The spacer element group may include a first spacer element P1, a second spacer element P2, and a third spacer element P3. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. The first side face of each element is also called the near-human-eye side face, and the second side face is also called the near-screen side face.

[0082] The first lens E1 has a positive focal power. Its first side S1 is convex, and its second side S2 is flat. The second lens E2 has a positive focal power. Its first side S3 is convex, and its second side S4 is convex. The third lens E3 has a negative focal power. Its first side S5 is concave, and its second side S6 is concave. The fourth lens E4 has a negative focal power. Its first side S7 is concave, and its second side S8 is flat. The reflective polarizing element RP and the first quarter-wave plate QWP1 are attached to the second side S2 of the first lens E1. The partial reflection element BS is attached to the second side S6 of the third lens E3. The second quarter-wave plate QWP2 and the polarizer LP are attached to the second side S8 of the fourth lens E4. It should be noted that the surfaces S1 to S8 are not shown in Figure 2 the figure.

[0083] In this example, an image plane IMG can be provided on the second side of the visual system. A display screen can be provided on the image plane IMG. The light from the display screen passes through the polarizer LP, the second quarter-wave plate QWP2, the fourth lens E4, the third lens E3, the second lens E2, and the first quarter-wave plate QWP1 in sequence, reaches the reflective polarizing element RP, and then is reflected at the reflective polarizing element RP to form the first reflected image light. The first reflected image light passes through the first quarter-wave plate QWP1, the second lens E2, and the third lens E3 in sequence and reaches the partial reflection element BS on the second side S6 of the third lens E3, and then is reflected at the partial reflection element BS to form the second reflected image light. The second reflected image light passes through the third lens E3, the second lens E2, the first quarter-wave plate QWP1, the reflective polarizing element RP, and the first lens E1 to the aperture STO and finally projects onto the user's eyes. For example, the light after two reflections of this visual system finally projects onto the user's eyes. A protective glass can also be provided between the image plane IMG and the polarizer LP. Among them, the aperture STO, the partial reflection element BS, and the image plane IMG are not shown in Figure 2 the figure.

[0084] Table 1 shows the basic parameter table of the visual system in Embodiment 1. Among them, the unit of the radius of curvature and the thickness / distance is millimeter (mm). The image light from the display screen passes through each element in the order from No. 27 to No. 1 and projects onto the user's eyes.

[0085]

[0086] Table 1

[0087] In this embodiment, any one of the object side and the image side of the first side S3 and the second side S4 of the second lens E2 and the first side S7 of the fourth lens E4 is an aspherical surface. The surface profile x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0088]

[0089] Wherein, x is the sagitta, which is the distance from the vertex of the aspherical surface to the position along the optical axis at a height of h; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 2 above); k is the conic coefficient; Ai is the correction coefficient of the i-th order of the aspherical surface. Table 2 gives the higher-order term coefficients A4, A6, A8, A 10 、A 12 、A 14 、A 16 、A 18 and A 20 .

[0090] Surface number A4 A6 A8 A10 A12 A14 A16 A18 A20 S3 -1.8064E-05 -3.1946E-08 1.6169E-11 8.8927E-14 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S4 -6.1703E-06 -5.1619E-09 1.0730E-10 -1.7912E-13 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S7 2.2471E-01 -2.0151E-02 4.3479E-04 -3.0171E-03 -9.1056E-04 -4.3575E-04 2.7962E-06 1.5287E-04 0.0000E+00

[0091] Table 2

[0092] Example 2

[0093] The visual system according to Embodiment 2 of the present application will be described below with reference to Figure 3 .

[0094] As Figure 3 shown, the visual system may include a lens barrel P0 and an optical element group and a spacer element group assembled in the lens barrel P0.

[0095] The optical element group includes 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 fourth lens E4, a second quarter-wave plate QWP2, and a polarizer LP arranged in sequence along the optical axis from the first side to the second side. An aperture STO is disposed between the first side and the first lens E1. An image plane IMG may be disposed on the second side of the visual system, and a protective glass may also be disposed between the image plane IMG and the polarizer LP. The spacer element group may include a first spacer element P1, a second spacer element P2, and a third spacer element P3. Among them, the aperture STO, the partially reflective element BS, and the image plane IMG are not shown in Figure 3 .

[0096] The structure of the optical element group in this embodiment is the same as that of the optical element group in Embodiment 1, that is, the basic parameter table of the visual system in this embodiment is the same as Table 1, and the higher-order term coefficient table of the aspherical surface is the same as Table 2.

[0097] The difference between this embodiment and Embodiment 1 lies in the structural dimensions of the lens barrel and some spacer elements, the spacing of some spacer elements along the optical axis, and other parameters. The numerical values of multiple parameters of the lens barrel and spacer elements included in the visual system of this embodiment and Embodiment 1 are shown in Table 8 below.

[0098] Example 3

[0099] The following refers to Figure 4 Describe the visual system according to Embodiment 3 of the present application.

[0100] As Figure 4 shown, the visual system may include a lens barrel P0 and an optical element group and a spacer element group assembled in the lens barrel P0.

[0101] The optical element group includes 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 fourth lens E4, a second quarter-wave plate QWP2, and a polarizer LP arranged in sequence along the optical axis from the first side to the second side. An aperture STO is provided between the first side and the first lens E1. An image plane IMG may be provided on the second side of the visual system, and a protective glass may also be provided between the image plane IMG and the polarizer LP. The spacer element group may include a first spacer element P1, a second spacer element P2, and a third spacer element P3. Among them, the aperture STO, the partially reflective element BS, and the image plane IMG are not shown in Figure 4 it.

[0102] The structure of the optical element group in this embodiment is the same as that of the optical element group in Embodiment 1, that is, the basic parameter table of the visual system in this embodiment is the same as Table 1, and the high-order term coefficient table of the aspherical surface is the same as Table 2.

[0103] The difference between this embodiment and Embodiment 1 lies in the structural dimensions of the lens barrel and some spacer elements, the spacing of some spacer elements along the optical axis, and other parameters. The numerical values of multiple parameters of the lens barrel and spacer elements included in the visual system of this embodiment and Embodiment 1 are shown in Table 8 below.

[0104] Figure 5A shows the axial chromatic aberration curves of the visual systems of Embodiments 1, 2, and 3, which represent the deviation of the convergence points of light rays of different wavelengths after passing through the visual system. Figure 5B shows the astigmatism curves of the visual systems of Embodiments 1, 2, and 3, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field angles. Figure 5C shows the distortion curves of the visual systems of Embodiments 1, 2, and 3, which represent the distortion magnitude values corresponding to different field angles. Figure 5D shows the modulation transfer function curves of the visual systems of Embodiments 1, 2, and 3. According toFigures 5A to 5D It can be seen that the visual systems given in Embodiments 1, 2, and 3 can achieve good imaging quality.

[0105] Example 4

[0106] The following refers to Figure 6 Describe the visual system according to Embodiment 4 of the present application.

[0107] As Figure 6 shown, the visual system may include a lens barrel P0 and an optical element group and a spacer element group assembled in the lens barrel P0.

[0108] The optical element group includes 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, a fourth lens E4, a second quarter-wave plate QWP2, and a polarizer LP arranged in sequence along the optical axis from the first side to the second side. The aperture stop STO is disposed between the first side and the first lens E1. The spacer element group may include a first spacer element P1, a second spacer element P2, and a third spacer element P3. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. The first side surface of each element is also referred to as the near-human-eye side surface, and the second side surface is also referred to as the near-screen side surface.

[0109] The first lens E1 has a positive optical power, its first side surface S1 is convex, and its second side surface S2 is flat. The second lens E2 has a positive optical power, its first side surface S3 is concave, and its second side surface S4 is convex. The third lens E3 has a negative optical power, its first side surface S5 is concave, and its second side surface S6 is convex. The fourth lens E4 has a positive optical power, its first side surface S7 is convex, and its second side surface S8 is flat. The reflective polarizing element RP and the first quarter-wave plate QWP1 are attached to the second side surface S2 of the first lens E1. The partial reflection element BS is attached to the second side surface S6 of the third lens E3. The second quarter-wave plate QWP2 and the polarizer LP are attached to the second side surface S8 of the fourth lens E4. It should be noted that the surfaces S1 to S8 are not shown in Figure 6 it.

[0110] In this example, an image surface IMG may be provided on the second side of the visual system, and a display screen may be provided on the image surface IMG. The light from the display screen sequentially passes through a polarizer LP, a second quarter-wave plate QWP2, a fourth lens E4, a third lens E3, a second lens E2, a first quarter-wave plate QWP1, reaches a reflective polarizing element RP, and then is reflected at the reflective polarizing element RP to form a first reflected image light. The first reflected image light sequentially passes through the first quarter-wave plate QWP1, the second lens E2, the third lens E3 and reaches a partial reflection element BS on the second side surface S6 of the third lens E3, and then is reflected at the partial reflection element BS to form a second reflected image light. The second reflected image light sequentially passes through the third lens E3, the second lens E2, the first quarter-wave plate QWP1, the reflective polarizing element RP, a first lens E1 to a stop STO and finally projects onto the user's eyes. For example, the light after two reflections of the visual system finally projects onto the user's eyes. A protective glass may also be provided between the image surface IMG and the polarizer LP. Among them, the stop STO, the partial reflection element BS and the image surface IMG are not shown in Figure 6 shown.

[0111] Table 3 shows the basic parameter table of the visual system of Example 4, where the units of the radius of curvature and the thickness / distance are both millimeters (mm). The image light from the display screen passes through each element in the order of serial number 27 to serial number 1 and projects onto the user's eyes.

[0112]

[0113]

[0114] Table 3

[0115] In this embodiment, any one of the object side surface and the image side surface of the first side surface S3 and the second side surface S4 of the second lens E2, the first side surface S5 and the second side surface S6 of the third lens, and the first side surface S7 of the fourth lens E4 is an aspherical surface. Table 4 gives the higher-order term coefficients A4, A6, A8, A 10 , A 12 , A 14 , A 16 , A 18 and A 20 that can be used for each aspherical surface S3 - S7 in Example 4.

[0116] Surface number A4 A6 A8 A10 A12 A14 A16 A18 A20 S3 3.2030E-05 1.2526E-08 -7.4935E-10 2.2518E-12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S4 1.6866E-04 -8.3155E-07 1.7344E-09 1.3820E-12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S5 6.3892E-05 -7.8509E-07 5.9444E-09 -1.3170E-11 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S6 -2.5017E-05 1.5251E-07 -6.6248E-11 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S7 2.4650E-01 -1.5904E-02 -3.2258E-03 -1.8287E-04 2.6187E-04 2.0432E-06 -3.4679E-05 -5.2321E-08 0.0000E+00

[0117] Table 4

[0118] Example 5

[0119] The following refers toFigure 7 Describe the visual system according to Embodiment 5 of the present application.

[0120] As Figure 7 shown, the visual system may include a lens barrel P0, and an optical element group and a spacer element group assembled within the lens barrel P0.

[0121] The optical element group includes 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, a fourth lens E4, a second quarter-wave plate QWP2, and a polarizer LP arranged in sequence along the optical axis from the first side to the second side. An aperture STO is disposed between the first side and the first lens E1. An image plane IMG may be disposed on the second side of the visual system, and a protective glass may also be disposed between the image plane IMG and the polarizer LP. The spacer element group may include a first spacer element P1, a second spacer element P2, and a third spacer element P3. Among them, the aperture STO, the partial reflection element BS, and the image plane IMG are not shown in Figure 7 it.

[0122] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 4, that is, the basic parameter table of the visual system of this embodiment is the same as Table 3, and the high-order term coefficient table of the aspherical surface is the same as Table 4.

[0123] The difference between this embodiment and Embodiment 4 lies in that the structural dimensions of the lens barrel and some spacer elements, the spacing of some spacer elements in the optical axis direction, and other parameters are different. The numerical values of multiple parameters of the lens barrel and spacer elements included in the visual systems of this embodiment and Embodiment 4 are as shown in Table 8 hereinafter.

[0124] Example 6

[0125] The following refers to Figure 8 Describe the visual system according to Embodiment 6 of the present application.

[0126] As Figure 8 shown, the visual system may include a lens barrel P0, and an optical element group and a spacer element group assembled within the lens barrel P0.

[0127] The optical element group includes 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, a fourth lens E4, a second quarter-wave plate QWP2, and a polarizer LP, which are arranged in sequence along the optical axis from the first side to the second side. An aperture STO is disposed between the first side and the first lens E1. An image plane IMG may be disposed on the second side of the visual system, and a protective glass may also be disposed between the image plane IMG and the polarizer LP. The spacer element group may include a first spacer element P1, a second spacer element P2, and a third spacer element P3. Among them, the aperture STO, the partial reflection element BS, and the image plane IMG are not shown in Figure 8 shown.

[0128] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 4, that is, the basic parameter table of the visual system of this embodiment is the same as Table 3, and the high-order term coefficient table of the aspherical surface is the same as Table 4.

[0129] The difference between this embodiment and Embodiment 4 lies in that the structural dimensions of the lens barrel and some spacer elements, the spacing of some spacer elements along the optical axis direction, and other parameters are different. The numerical values of multiple parameters of the lens barrel and spacer elements included in the visual systems of this embodiment and Embodiment 4 are shown in Table 8 below.

[0130] Figure 9A The axial chromatic aberration curves of the visual systems of Embodiments 4, 5, and 6 are shown, which represent the deviation of the focusing points of light rays of different wavelengths after passing through the visual system. Figure 9B 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 9C 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. Figure 9D The modulation transfer function curves of the visual systems of Embodiments 4, 5, and 6 are shown. According to Figures 9A to 9D it can be known that the visual systems given in Embodiments 4, 5, and 6 can achieve good imaging quality.

[0131] Example 7

[0132] The following refers to Figure 10 the visual system according to Embodiment 7 of the present application.

[0133] As Figure 10 shown, the visual system may include a lens barrel P0 and an optical element group and a spacer element group assembled in the lens barrel P0.

[0134] The optical element group includes 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, a fourth lens E4, a second quarter-wave plate QWP2, and a polarizer LP, which are arranged in sequence along the optical axis from the first side to the second side. The aperture STO is disposed between the first side and the first lens E1. The spacer element group may include a first spacer element P1, a second spacer element P2, and a third spacer element P3. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. The first side surface of each element is also referred to as the near-eye side surface, and the second side surface is also referred to as the near-screen side surface.

[0135] The first lens E1 has a positive optical power, its first side surface S1 is convex, and its second side surface S2 is flat. The second lens E2 has a positive optical power, its first side surface S3 is concave, and its second side surface S4 is convex. The third lens E3 has a negative optical power, its first side surface S5 is concave, and its second side surface S6 is concave. The fourth lens E4 has a negative optical power, its first side surface S7 is concave, and its second side surface S8 is flat. The reflective polarizing element RP and the first quarter-wave plate QWP1 are attached to the second side surface S2 of the first lens E1. The partial reflection element BS is attached to the second side surface S6 of the third lens E3. The second quarter-wave plate QWP2 and the polarizer LP are attached to the second side surface S8 of the fourth lens E4. It should be noted that the surfaces S1 to S8 are not shown in Figure 10 the figure.

[0136] In this example, an image plane IMG may be provided on the second side of the visual system, and a display screen may be provided on the image plane IMG. The light from the display screen sequentially passes through the polarizer LP, the second quarter-wave plate QWP2, the fourth lens E4, the third lens E3, the second lens E2, and the first quarter-wave plate QWP1, reaches the reflective polarizing element RP, and then is reflected at the reflective polarizing element RP to form a first reflected image light. The first reflected image light sequentially passes through the first quarter-wave plate QWP1, the second lens E2, the third lens E3 and reaches the partial reflection element BS on the second side surface S6 of the third lens E3, and then is reflected at the partial reflection element BS to form a second reflected image light. The second reflected image light sequentially passes through the third lens E3, the second lens E2, the first quarter-wave plate QWP1, the reflective polarizing element RP, the first lens E1 to the aperture STO and finally projects onto the user's eyes. For example, the light after two reflections of this visual system finally projects onto the user's eyes. A protective glass may also be provided between the image plane IMG and the polarizer LP. Among them, the aperture STO, the partial reflection element BS, and the image plane IMG are not shown in Figure 10 the figure.

[0137] Table 5 shows the basic parameter table of the visual system of Example 7, where the unit of the radius of curvature and the thickness / distance is millimeter (mm). The image light from the display screen passes through each element in the order of serial number 27 to serial number 1 and is projected onto the user's eyes.

[0138]

[0139] Table 5

[0140] In this embodiment, any one of the object side and the image side of the first side S3 and the second side S4 of the second lens E2 and the first side S7 of the fourth lens E4 is an aspherical surface. Table 6 gives the higher-order term coefficients A4, A6, A8, A 10 、A 12 、A 14 、A 16 、A 18 and A 20 .

[0141] Surface number A4 A6 A8 A10 A12 A14 A16 A18 A20 S3 -3.3358E-05 -4.4330E-08 4.9884E-11 -3.3312E-13 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S4 -1.6301E-05 -4.7698E-09 3.4362E-11 -2.8834E-13 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S7 1.8468E-01 -2.4371E-02 -1.2344E-03 -3.5291E-03 -2.0958E-03 -7.1887E-04 -2.9361E-04 6.2643E-05 0.0000E+00

[0142] Table 6

[0143] Example 8

[0144] The following refers to Figure 11 to describe the visual system according to Embodiment 8 of the present application.

[0145] As Figure 11 shown, the visual system may include a lens barrel P0 and an optical element group and a spacer element group assembled in the lens barrel P0.

[0146] The optical element group includes 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, a fourth lens E4, a second quarter-wave plate QWP2, and a polarizer LP arranged in sequence along the optical axis from the first side to the second side. An aperture STO is disposed between the first side and the first lens E1. An image plane IMG may be disposed on the second side of the visual system, and a protective glass may also be disposed between the image plane IMG and the polarizer LP. The spacer element group may include a first spacer element P1, a second spacer element P2, and a third spacer element P3. Among them, the aperture STO, the partial reflection element BS, and the image plane IMG are not shown in Figure 11 .

[0147] The structure of the optical element group in this embodiment is the same as that of the optical element group in Embodiment 7, that is, the basic parameter table of the visual system in this embodiment is the same as Table 5, and the higher-order term coefficient table of the aspherical surface is the same as Table 6.

[0148] The difference between this embodiment and Embodiment 7 lies in the structural dimensions of the lens barrel and some spacer elements, the spacing of some spacer elements along the optical axis, and other parameters. The numerical values of multiple parameters of the lens barrel and spacer elements included in the visual system of this embodiment and Embodiment 7 are shown in Table 8 below.

[0149] Example 9

[0150] The following refers to Figure 12 Describe the visual system according to Embodiment 9 of the present application.

[0151] As Figure 12 shown, the visual system may include a lens barrel P0 and an optical element group and a spacer element group assembled in the lens barrel P0.

[0152] The optical element group includes 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, a fourth lens E4, a second quarter-wave plate QWP2, and a polarizer LP arranged in sequence along the optical axis from the first side to the second side. An aperture STO is provided between the first side and the first lens E1. An image plane IMG may be provided on the second side of the visual system, and a protective glass may also be provided between the image plane IMG and the polarizer LP. The spacer element group may include a first spacer element P1, a second spacer element P2, and a third spacer element P3. Among them, the aperture STO, the partial reflection element BS, and the image plane IMG are not shown in Figure 12 it.

[0153] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 7, that is, the basic parameter table of the visual system of this embodiment is the same as Table 5, and the high-order term coefficient table of the aspherical surface is the same as Table 6.

[0154] The difference between this embodiment and Embodiment 7 lies in the structural dimensions of the lens barrel and some spacer elements, the spacing of some spacer elements along the optical axis, and other parameters. The numerical values of multiple parameters of the lens barrel and spacer elements included in the visual system of this embodiment and Embodiment 7 are shown in Table 8 below.

[0155] Figure 13A The axial chromatic aberration curves of the visual systems of Embodiments 7, 8, and 9 are shown, which represent the deviation of the convergence points of light rays of different wavelengths after passing through the visual system. Figure 13B 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 13C 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. Figure 13DShows the modulation transfer function curves of the visual systems of Examples 7, 8, and 9. According to Figures 13A to 13D it can be known that the visual systems given in Examples 7, 8, and 9 can achieve good imaging quality.

[0156] Table 7 shows the values of the parameters f, f1, f2, f3, f4, TD, fz1, and fz2 for each of the Examples 1-9.

[0157]

[0158]

[0159] Table 7

[0160] Table 8 shows the values of the parameters d1s, d1m, D1s, D1m, d2s, d2m, D2s, D2m, d3s, d3m, D3s, D3m, d0s, d0m, D0s, D0m, EP01, CP1, EP12, CP2, EP23, CP3, and L for each of the Examples 1-9. Among them, at least some of 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.

[0161] Conditional / Example 1 2 3 4 5 6 7 8 9 d1s 25.942 26.371 25.942 27.360 27.360 27.367 26.741 26.741 25.441 d1m 27.242 27.416 27.242 28.536 28.536 28.536 28.042 27.244 26.742 D1s 30.627 30.254 30.467 32.252 32.252 30.552 31.960 31.960 30.660 D1m 30.619 30.081 30.459 32.045 32.045 30.345 31.953 31.953 30.653 d2s 23.518 23.680 23.358 24.718 24.718 24.718 24.924 24.924 24.924 d2m 23.518 23.680 23.358 24.718 24.718 24.718 24.924 24.924 24.924 D2s 31.200 31.200 31.040 32.400 32.400 30.700 32.000 32.000 30.700 D2m 31.200 31.200 31.040 32.400 32.400 30.700 32.000 32.000 30.700 d3s 21.042 21.167 21.305 19.902 19.902 19.902 20.438 20.438 20.438 d3m 21.042 21.167 21.305 19.902 19.902 19.902 20.438 20.438 20.438 D3s 30.800 30.800 30.640 32.000 32.000 30.300 31.600 31.600 30.300 D3m 30.800 30.800 30.640 32.000 32.000 30.300 31.600 31.600 30.300 d0s 33.000 33.000 32.840 34.418 34.418 32.918 33.814 33.814 32.514 d0m 17.664 17.664 17.664 18.868 18.868 17.971 18.477 18.477 18.010 D0s 36.000 36.000 35.820 37.600 36.009 34.509 36.400 36.400 35.681 D0m 34.085 34.085 33.905 35.530 34.330 30.154 34.899 34.899 34.951 EP01 2.609 2.870 2.609 1.716 1.716 1.716 1.666 1.666 1.666 CP1 2.500 2.500 2.500 1.430 1.480 1.430 1.655 1.655 1.655 EP12 4.250 4.250 4.250 5.000 4.950 5.000 4.300 4.300 4.300 CP2 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 EP23 8.100 8.100 8.100 9.050 9.050 9.050 9.500 9.500 9.500 CP3 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 L 23.000 23.260 23.000 23.000 23.000 22.400 23.000 23.000 22.650

[0162] Table 8

[0163] Table 9 shows the values of the conditional expressions for each of the Examples 1-9.

[0164]

[0165]

[0166] Table 9

[0167] This application also provides an optical device, which can be an independent projection device such as a projector, or a projection module integrated on a mobile electronic device such as a virtual reality device. This optical device is equipped with the visual system described above.

[0168] The above description is only for the preferred embodiments of this application and the description of the applied technical principles. Those skilled in the art should understand that the scope of the application involved in this application is not limited to the technical solutions formed by the specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the application concept. For example, the technical solutions formed by mutually replacing the above features with the (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A visual system, characterized in that: include: An optical element group, comprising, 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 positive optical power, a third lens with negative optical power, a partial reflecting element, a fourth lens with optical power, a second quarter wave plate and a polarizing plate; wherein the first side surface of the first lens is a convex surface, and the second side surface is a plane; the second side surface of the second lens is a convex surface; the first side surface of the third lens is a concave surface; and the second side surface of the fourth lens is a plane; a spacer element group, comprising a first spacer element, a second spacer element, and a third spacer element, wherein the first spacer element is disposed on the second side surface of the first lens and in contact with the second side surface of the first lens, the second spacer element is disposed on the second side surface of the second lens and in contact with the second side surface of the second lens, and the third spacer element is disposed on the second side surface of the third lens and in contact with the second side surface of the third lens; and a lens barrel, in which the spacer element group and the optical element group are assembled; Wherein, the number of lenses with optical power in the visual system is four; Wherein, the maximum thickness CP2 of the second spacing element and the maximum thickness CP3 of the third spacing element satisfy: CP2=CP3; The center thickness CTR of the reflective polarizing element on the optical axis, the center thickness CTQ1 of the first quarter-wave plate on the optical axis, the axial distance T12 from the second side of the first lens to the first side of the second lens and the maximum thickness CP1 of the first spacing element satisfy: 1.2<(CTR+CTQ1+T12) / CP1<2.

1.

2. The visual system according to claim 1, characterized in that: The combined focal length fz2 of the fourth lens, the second quarter wave plate and the polarizer, the inner diameter d0m of the second side end surface of the lens barrel and the outer diameter D0m of the second side end surface of the lens barrel satisfy: 0.4<|fz2| / (d0m+D0m)<2.

4.

3. The visual system according to claim 1, characterized in that: The axial distance TD from the first side surface of the first lens to the second side surface of the fourth lens and the distance EP23 between the second spacing element and the third spacing element along the optical axis satisfy: 2.6 <TD / EP23<3.2。 4. The visual system according to claim 1, characterized in that: The inner diameter d0s of the first side end surface of the lens barrel and the curvature radius R1 of the first side surface of the first lens satisfy: 1.5 <d0s / R1≤1.64。 5. The visual system according to claim 1, characterized in that: The outer diameter D0s of the first side end surface of the lens barrel and the distance L between the first side end surface of the lens barrel and the second side end surface of the lens barrel along the optical axis satisfy: 1.5 <D0s / L≤1.63。 6. The visual system according to claim 1, characterized in that: The effective focal length f1 of the first lens, the inner diameter d0s of the first side end surface of the lens barrel, and the inner diameter d0m of the second side end surface of the lens barrel satisfy: 2.76≤f1 / (d0s-d0m)<3.

0.

7. The visual system according to any one of claims 1 to 6, characterized in that: The combined focal length fz1 of the first lens, the reflective polarizing element and the first quarter-wave plate, the outer diameter D1s of the first side of the first spacing element, the effective focal length f2 of the second lens and the outer diameter D1m of the second side of the first spacing element satisfy: 1.98≤(fz1 / D1s)×(f2 / D1m)<2.

8.

8. The visual system according to any one of claims 1 to 6, characterized in that: An inner diameter d2s of the first side surface of the second spacer element and a center thickness CT2 of the second lens on the optical axis satisfy: 3.8≤d2s / CT2≤4.

15.

9. The visual system according to any one of claims 1 to 6, characterized in that: The effective focal length f3 of the third lens, the inner diameter d2m of the second side surface of the second spacing element, and the outer diameter D2m of the second side surface of the second spacing element satisfy: -1.3 <f3 / (d2m+D2m)<-0.65。 10. The visual system according to any one of claims 1 to 6, characterized in that: The outer diameter D2s of the first 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: 0.3 <D2s / |R4+R5|<0.8。 11. The visual system according to any one of claims 1 to 6, characterized in that: An inner diameter d3s of the first side surface of the third spacing element, an inner diameter d3m of the second side surface of the third spacing element, and a center thickness CT3 of the third lens on the optical axis satisfy: 6.6<(d3s+d3m) / CT3≤7.

71.

12. The visual system according to any one of claims 1 to 6, characterized in that: An outer diameter D3s of the first side surface of the third spacing element, an outer diameter D3m of the second side surface of the third spacing element and a total effective focal length f of the visual system satisfy: 1.4<(D3s+D3m) / f≤1.

52.

13. The visual system according to any one of claims 1 to 6, characterized in that: The total effective focal length f of the visual system, the distance EP12 between the first spacing element and the second spacing element along the optical axis, and the maximum thickness CP2 of the second spacing element satisfy: 8.3 <f / (EP12+CP2)<9.8。 14. The visual system according to any one of claims 1 to 6, characterized in that: The distance EP01 between the first side end surface of the lens barrel and the first spacer element along the optical axis, the inner diameter d1m of the second side surface of the first spacer element, and the inner diameter d1s of the first side surface of the first spacer element satisfy: 1.28≤EP01 / (d1m-d1s)≤3.

31.

15. The visual system according to any one of claims 1 to 6, characterized in that: The distance EP23 between the second spacing element and the third spacing element along the optical axis, the distance EP01 between the first side end surface of the lens barrel and the first spacing element along the optical axis, and the distance EP12 between the first spacing element and the second spacing element along the optical axis satisfy: 1.1 <EP23 / (EP01+EP12)<1.6。

Images