Visual optical system

Abstract

The invention discloses a visual optical system, which comprises an optical element group and a spacing element group, the optical element group sequentially comprises a first lens with positive focal power, a reflective polarizing element, a first quarter-wave plate, a second lens with positive focal power, a third lens with negative focal power, a partial reflection element, a fourth lens with negative focal power, a second quarter-wave plate and a polarizing film from the first side to the second side along the optical axis; the spacing element group comprises a first spacing element and a third spacing element; the visual optical system meets the following conditions: R6 / tan (beta1.0) is more than or equal to-14.05 mm and less than or equal to-11.86 mm and 2.0 lt; f / (EP13 + CP3) lt; and 2.35.

Description

Technical Field

[0001] This application relates to the field of optical devices, and particularly to a visual optical system. Background Art

[0002] The visual optical systems of virtual reality devices or augmented reality devices are mainly divided into three types: visual optical systems using aspherical lenses, visual optical systems using Fresnel lenses, and catadioptric visual optical systems. Among them, the catadioptric visual optical system is a major innovation in the visual optical system itself and reserves space for the overall design of virtual reality devices or augmented reality devices, and has become the mainstream trend of research and development.

[0003] The catadioptric visual optical system shortens the body length of the visual optical system by folding the optical path, thereby shifting the center of gravity of the virtual reality device or augmented reality device backward and enhancing the user experience. However, the catadioptric visual optical system usually has a relatively serious ghost image problem, which affects the imaging effect of the visual optical system. Summary of the Invention

[0004] One aspect of this application provides a visual optical system, which includes a lens barrel and an optical element group and a spacer element group accommodated in the lens barrel. The optical element group includes, in order along the optical axis from the first side to the second side: a first lens with positive optical power, whose first side is convex; a reflective polarizing element; a first quarter-wave plate; a second lens with positive optical power, whose first side is flat and the second side is convex; a third lens with negative optical power, whose first side is concave and the second side is convex; a partially reflective element; a fourth lens with negative optical power, whose first side is concave and the second side is flat; a second quarter-wave plate; a polarizer; wherein, the number of lenses with optical power in the optical element group is four; the spacer element group includes a first spacer element and a third spacer element. The first spacer element is located between the first lens and the second lens and is in contact with the second side of the first lens. The third spacer element is located between the third lens and the fourth lens and is in contact with the second side of the third lens; and the visual optical system satisfies: -14.05mm ≤ R6 / tan(β 1.0 ) ≤ -11.86mm and 2.0 < f / (EP13 + CP3) < 2.35, where R6 is the curvature radius of the second side of the third lens, and β 1.0 is the angle between the tangent line of the second side of the third lens at the intersection position of the chief ray of the 1.0 field of view after being reflected by the partially reflective element and the optical axis, f is the total effective focal length of the visual optical system, EP13 is the distance along the optical axis from the second side of the first spacer element to the first side of the third spacer element, and CP3 is the maximum thickness of the third spacer element.

[0005] According to an exemplary embodiment of the present application, the visual optical system satisfies: 1.25 ≤ (d1m + D1m) / fz1 ≤ 1.46, where d1m is the inner diameter of the second side surface of the first spacer element, D1m is the outer diameter of the second side surface of the first spacer element, and fz1 is the combined focal length of the reflective polarizing element, the first quarter-wave plate, and the second lens.

[0006] According to an exemplary embodiment of the present application, the visual optical system satisfies: 3.5 < (CTR + CTQ1 + CT2) / CP1 < 6.65, where CTR is the central thickness of the reflective polarizing element on the optical axis, CTQ1 is the central thickness of the first quarter-wave plate on the optical axis, CT2 is the central thickness of the second lens on the optical axis, and CP1 is the maximum thickness of the first spacer element.

[0007] According to an exemplary embodiment of the present application, the visual optical system satisfies: -2.5 < fz2 / D0m < -2.2, where fz2 is the combined focal length of the fourth lens, the second quarter-wave plate, and the polarizer, and D0m is the outer diameter of the second end surface of the lens barrel.

[0008] According to an exemplary embodiment of the present application, the visual optical system satisfies: 2.5 < EP13 / T23 < 3.0, where T23 is the distance on the optical axis from the second side surface of the second lens to the first side surface of the third lens.

[0009] According to an exemplary embodiment of the present application, the visual optical system satisfies: 4.19 mm ≤ d3s / tan(β 0.8 ) ≤ 5.05 mm, where d3s is the inner diameter of the first side surface of the third spacer element, and β 0.8 is the angle between the tangent of the intersection position of the chief ray of the 0.8 field of view after being reflected by the partial reflection element and the second side surface of the third lens and the optical axis.

[0010] According to an exemplary embodiment of the present application, the visual optical system satisfies: 6.65 < (D1s / d1s)*tan(β 0.9 ) < 6.85, where D1s is the outer diameter of the first side surface of the first spacer element, d1s is the inner diameter of the first side surface of the first spacer element, and β 0.9 is the angle between the tangent of the intersection position of the chief ray of the 0.9 field of view after being reflected by the partial reflection element and the second side surface of the third lens and the optical axis.

[0011] According to an exemplary embodiment of the present application, the visual optical system satisfies: 0.95 < (d0s + D0s) / f1 < 1.4, where d0s is the inner diameter of the first end surface of the lens barrel, D0s is the outer diameter of the first end surface of the lens barrel, and f1 is the effective focal length of the first lens.

[0012] According to an exemplary embodiment of the present application, the visual optical system satisfies: 0.85 < CT1 / EP01 < 1.7, where CT1 is the central thickness of the first lens on the optical axis, and EP01 is the distance along the optical axis between the first end face of the barrel and the first side face of the first spacer element.

[0013] According to an exemplary embodiment of the present application, the visual optical system satisfies: 2.70 ≤ f2 / L ≤ 3.43, where f2 is the effective focal length of the second lens, and L is the distance along the optical axis between the first end face of the barrel and the second end face of the barrel.

[0014] According to an exemplary embodiment of the present application, the visual optical system satisfies: 1.15 < f3 / f4 < 1.25 and 1.0 < D3m / d3m < 1.25, where f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, D3m is the outer diameter of the second side face of the third spacer element, and d3m is the inner diameter of the second side face of the third spacer element.

[0015] According to an exemplary embodiment of the present application, the visual optical system satisfies: -1.85 < R7 / D3s < -1.5, where R7 is the radius of curvature of the first side face of the fourth lens, and D3s is the outer diameter of the first side face of the third spacer element.

[0016] According to an exemplary embodiment of the present application, the visual optical system satisfies: 1.74 ≤ d0m / TD ≤ 2.51, where d0m is the inner diameter of the second end face of the barrel, and TD is the distance along the optical axis between the first side face of the first lens and the second side face of the fourth lens.

[0017] According to an exemplary embodiment of the present application, the visual optical system satisfies: 0.9 < R1 / d0s < 1.0, where R1 is the radius of curvature of the first side face of the first lens, and d0s is the inner diameter of the first end face of the barrel.

[0018] Another aspect of the present application provides a visual optical system, which includes a lens barrel and an optical element group and a spacing element group contained in the lens barrel, wherein the optical element group includes, in order from the first side to the second side along the optical axis: a first lens with positive optical power, whose first side surface is a convex surface; a reflective polarizing element; a first quarter wave plate; a second lens with positive optical power, whose first side surface is a plane and whose second side surface is a convex surface; a third lens with negative optical power, whose first side surface is a concave surface and whose second side surface is a convex surface; a partial reflecting element; a fourth lens with negative optical power, whose first side surface is a concave surface and whose second side surface is a plane; a second quarter wave plate; a polarizing plate; wherein the number of lenses with optical power in the optical element group is four; the spacing element group includes a first spacing element and a third spacing element, the first spacing element is located between the first lens and the second lens and contacts the second side surface of the first lens, the third spacing element is located between the third lens and the fourth lens and contacts the second side surface of the third lens; and the visual optical system satisfies: -14.05mm≤R6 / tan(β 1.0 )≤-11.86mm and 6.65<(D1s / d1s)*tan(β 0.9 )<6.85, wherein R6 is the radius of curvature of the second side surface of the third lens, D1s is the outer diameter of the first side surface of the first spacing element, d1s is the inner diameter of the first side surface of the first spacing element, β 0.9 is the angle between the tangent line at the intersection of the principal ray and the second side surface of the third lens at the time of reflection and the optical axis under the field of view of 0.9, β 1.0 It is the angle between the tangent line at the intersection of the principal ray and the second side surface of the third lens during reflection and the optical axis under a field of view of 1.0.

[0019] The visual optical system provided by the present application is provided with a reflective polarizing element, a first quarter-wave plate, a partial reflective element, etc., so that the light can be refracted multiple times between the first lens and the fourth lens, and the optical path can be folded under the premise of ensuring the imaging quality, thereby effectively shortening the main body length of the visual optical system, and by controlling R6 / tan(β 1.0 ) and f / (EP13+CP3), which can make the angle of light passing through the first quarter-wave plate and the reflective polarizing element close to parallel, effectively reducing the reflection of excess light, thereby reducing the polarization angle effect, reducing the ghost image formed by light directly passing through the reflective polarizing element to reach the human eye, and improving imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0021] Figure 1 The structure arrangement and partial parameter diagram of a visual optical system of the present application are shown;

[0022] Figure 2 The β of a visual optical system of the present application is shown. 0.8 (a), β 0.9 (b), β 1.0 (c) Schematic diagram;

[0023] Figure 3 The structure diagram of the visual optical system of Example 1 of the present application is shown;

[0024] Figure 4 A schematic structural diagram of a visual optical system according to Embodiment 2 of the present application is shown;

[0025] Figure 5 A schematic diagram showing the structure of the visual optical system of Example 3 of the present application is shown.

[0026] Figure 6 The modulation transfer function (MTF) curves of the visual optical systems of Examples 1 to 3 of the present application are shown;

[0027] Figure 7 A schematic structural diagram of a visual optical system according to Embodiment 4 of the present application is shown;

[0028] Figure 8 A schematic structural diagram of a visual optical system according to Embodiment 5 of the present application is shown;

[0029] Fig. 9 A schematic structural diagram of a visual optical system according to Embodiment 6 of the present application is shown;

[0030] Fig.10 The modulation transfer function (MTF) curves of the visual optical systems of Examples 4 to 6 of the present application are shown;

[0031] Fig.11 A schematic structural diagram of a visual optical system according to Embodiment 7 of the present application is shown;

[0032] Fig.12 A schematic structural diagram of a visual optical system according to Embodiment 8 of the present application is shown;

[0033] Fig.13 A schematic structural diagram of a visual optical system according to Example 9 of the present application is shown;

[0034] Fig.14 The modulation transfer function (MTF) curves of the visual optical systems of Examples 7 to 9 of the present application are shown;

[0035] Fig.15 It shows that the visual optical system of the present application satisfies R6 / tan(β 1.0Ghost effect diagram when )=-13.54mm and f / (EP13+CP3)=2.16;

[0036] Fig.16 It shows that the visual optical system of the present application satisfies R6 / tan(β 1.0 Ghost effect diagram when )=-15mm and f / (EP13+CP3)=1.5;

[0037] Fig.17 It shows that the visual optical system of the present application satisfies R6 / tan(β 1.0 )=-10mm and f / (EP13+CP3)=2.8. DETAILED DESCRIPTION

[0038] In order to better understand the present application, a more detailed description will be made of various aspects of the present application 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 figure numerals refer to the same elements.

[0039] It should be noted that in this specification, the expressions of 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 teaching of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0040] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of illustration. 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 shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0041] In this document, 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 paraxial region refers to the region near the optical axis. The surface of each lens closest to the first side (e.g., the human eye side) is called the first side surface of the lens, and the surface of each lens closest to the second side (e.g., the display screen side) is called the second side surface of the lens.

[0042] It should also be understood that the terms "including" 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 combinations thereof. In addition, when describing the embodiments of the present application, the term "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0043] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as those commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0044] It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The following examples only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for those of ordinary skill in the art, without departing from the concept of the present application, several variations and improvements can also be made, which all belong to the protection scope of the present application.

[0045] The present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0046] Figure 1 The structural arrangement and partial parameter diagram of a visual optical system of the present application are shown as an example to facilitate a better understanding of the present application. Figure 1As shown, D0s is the outer diameter of the first side end surface of the lens barrel, d0s is the inner diameter of the first side end surface of the lens barrel, D3s is the outer diameter of the first side surface of the third spacing element, D1s is the outer diameter of the first side surface of the first spacing element, d1s is the inner diameter of the first side surface of the first spacing element, d3s is the inner diameter of the first side surface of the third spacing element, d3m is the inner diameter of the second side surface of the third spacing element, d1m is the inner diameter of the second side surface of the first spacing element, D1m is the outer diameter of the second side surface of the first spacing element, D3m is the outer diameter of the second side surface of the third spacing element, and d0m is The inner diameter of the second side end face of the lens barrel, D0m is the outer diameter of the second side end face of the lens barrel, EP01 is the distance between the first side end face of the lens barrel and the first side face of the first spacing element along the optical axis, EP13 is the distance from the second side face of the first spacing element to the first side face of the third spacing element along the optical axis, CP1 is the maximum thickness of the first spacing element, CP3 is the maximum thickness of the third spacing element, L is the distance from the first side end face of the lens barrel to the second side end face of the lens barrel along the optical axis, E1 is the first lens, E2 is the second lens, E3 is the third lens, and E4 is the fourth lens.

[0047] Figure 2 The β of the visual optical system in Example 1 of the present application is shown as an example. 0.8 (a), β 0.9 (b), β 1.0 (c) Schematic diagram. Figure 2 As shown in (a), β 0.8 is the angle between the tangent line of the second side surface of the third lens at the intersection of the main light of 0.8 field of view after being reflected by the partial reflective element and the optical axis. Figure 2 As shown in (b), β 0.9 is the angle between the tangent line of the second side surface of the third lens at the intersection of the main light of the 0.9 field of view after being reflected by the partial reflective element and the optical axis. Figure 2 As shown in (c), β 1.0 It is the angle between the tangent line of the second side surface of the third lens at the intersection of the main light of 1.0 field of view after being reflected by the partial reflective element and the optical axis.

[0048] refer to Figure 3 , Figure 4 , Figure 5 , Figure 7 , Figure 8 , Fig. 9 , Fig.11 , Fig.12 and Fig.13According to a first aspect of the present application, there is provided an ocular optical system, which includes an optical element group, which includes a first lens, a reflective polarizing element, a first quarter-wave plate, a second lens, a third lens, a partially reflecting element, a fourth lens, a second quarter-wave plate and a polarizer in sequence from the first side to the second side along the optical axis.

[0049] In an exemplary embodiment, the first lens may have positive optical power. The first side surface of the first lens is convex, and the second side surface is concave or convex and is a thin Fresnel surface.

[0050] In an exemplary embodiment, the second lens may have positive optical power. The first side surface of the second lens is a flat surface, and the second side surface is a convex surface.

[0051] In an exemplary embodiment, the third lens may have negative optical power. A first side surface of the third lens is a concave surface, and a second side surface is a convex surface.

[0052] In an exemplary embodiment, the fourth lens has negative optical power. A first side surface of the fourth lens is a concave surface, and a second side surface is a flat surface.

[0053] In an exemplary embodiment, the number of lenses with optical power in the optical element group is four. Each lens has at least a first side surface facing the first side and a second side surface facing the second side. Each lens has an effective diameter area through which light can pass and a non-effective diameter area surrounding the effective diameter area through which light cannot pass. Among the first lens to the fourth lens, any two adjacent lenses may have a spacing distance on the optical axis, and the spacing distance may be an air spacing.

[0054] In an exemplary embodiment, the first quarter wave plate is located on the first side of the second lens. The reflective polarizing element is located on the first side of the first quarter wave plate. Wherein, the first quarter wave plate is used to change the polarization state of the light, for example, converting circularly polarized light into linearly polarized light, or converting linearly polarized light into circularly polarized light. The circularly polarized light may include right-handed circularly polarized light or left-handed circularly polarized light. The linearly polarized light may include S-linearly polarized light or P-linearly polarized light. The reflective polarizing element is used to reflect linearly polarized light in a predetermined direction and transmit linearly polarized light orthogonal to the predetermined direction. For example, the reflective polarizing element may reflect S-linearly polarized light and transmit P-linearly polarized light, or the reflective polarizing element may reflect P-linearly polarized light and transmit S-linearly polarized light.

[0055] In an exemplary embodiment, the partial reflective element is located between the third lens and the fourth lens. Exemplarily, the partial reflective element is attached to the second side of the third lens. Exemplarily, the partial reflective element can have a semi-transmissive and semi-reflective effect on the light. By arranging the partial reflective element on the second side of the third lens, and combining the reflective polarizing element and the first quarter wave plate, the light can be refracted multiple times, effectively reducing the main body length of the visual optical system.

[0056] In an exemplary embodiment, the second quarter wave plate is located on a second side of the fourth lens. The polarizing plate is located on a second side of the second quarter wave plate.

[0057] In an exemplary embodiment, the second lens, the first quarter wave plate and the reflective polarizing element form a cemented lens with positive focal length. The first side surface of the second lens is set as a plane, so that the first quarter wave plate and the reflective polarizing element are attached to the plane. The plane attachment is conducive to improving the attachment effect and avoiding the large angle effect of the light at the first quarter wave plate and the reflective polarizing element, which leads to a decrease in polarization efficiency.

[0058] In an exemplary embodiment, the fourth lens, the second quarter wave plate and the polarizer form a cemented lens with negative focal power. The second side surface of the fourth lens is set as a plane, so that the second quarter wave plate and the polarizer are attached to the plane, and the plane attachment is conducive to improving the attachment effect.

[0059] In an exemplary embodiment, the visual optical system may further include an aperture, which is conducive to converging the light entering the visual optical system, reducing the maximum aperture of the system, and reducing the assembly sensitivity of the system, so as to further improve the imaging quality of the system. It should be noted that the aperture can be set between or on one side of any lens according to actual needs. Exemplarily, the aperture is set on the first side of the first lens.

[0060] In an exemplary embodiment, the second side of the visual optical system may be provided with an image surface. The image surface may be provided with a display screen.

[0061] In the present application, by setting a reflective polarizing element, a first quarter wave plate, a partial reflecting element, etc., the light can be refracted multiple times between the first lens and the fourth lens, and the optical path can be folded under the premise of ensuring the imaging quality, which effectively shortens the main body length of the visual optical system. Exemplarily, the light from the image surface is refracted when it is irradiated on the polarizing plate, and part of the light passes through the polarizing plate and passes through the second quarter wave plate, the fourth lens, the partial reflecting element, the third lens, the second lens and the first quarter wave plate in sequence, and is reflected for the first time at the reflective polarizing element. The first reflected light passes through the first quarter wave plate, the second lens, and the third lens in sequence, and is reflected for the second time at the partial reflecting element. The second reflected light passes through the third lens, the second lens, the first quarter wave plate, the reflective polarizing element, the first lens to the aperture and is finally projected to the human eye.

[0062] In an exemplary embodiment, the visual optical system further includes a spacer element group, which may include at least one spacer element, and the spacer element is disposed between the lenses and located in the non-effective diameter area of ​​the lenses. It should be understood that the present application does not specifically limit the number of spacer elements, and at least one spacer element is disposed between any two adjacent lenses, and the entire visual optical system may also include any number of spacer elements. The spacer elements help the visual optical system intercept excess refractive and reflective light paths, reduce stray light and ghosting, and improve imaging quality. The shapes of the spacer elements may be the same or different, as long as they can play a corresponding role.

[0063] In an exemplary embodiment, the spacer element group includes a first spacer element located between the first lens and the second lens and in contact with the second side surface of the first lens, and a third spacer element located between the third lens and the fourth lens and in contact with the second side surface of the third lens.

[0064] In an exemplary embodiment, the visual optical system further includes a lens barrel. The optical element group and the spacer element group are placed in the lens barrel. The lens barrel includes a first side end surface, a second side end surface, an outer annular surface, and an inner annular surface, wherein 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; in a direction perpendicular to the optical axis, the surface of the lens barrel farthest from the optical axis is the outer annular surface, and the surface of the lens barrel closest to the optical axis is the inner annular surface.

[0065] In an exemplary embodiment, the visual optical system of the present application may further include a filter as required, and the filter may filter light with different wavelengths. Exemplarily, the filter may be disposed between the fourth lens and the image plane.

[0066] In an exemplary embodiment, the visual optical system satisfies: -14.05 mm ≤ R6 / tan(β1.0) ≤ -11.86 mm and 2.0 < f / (EP13 + CP3) < 2.35, where R6 is the radius of curvature of the second surface of the third lens, β1.0 is the angle between the tangent of the intersection position of the chief ray of the 1.0 field of view after being reflected by the partial reflection element and the second surface of the third lens and the optical axis, f is the total effective focal length of the visual optical system, EP13 is the distance along the optical axis from the second surface of the first spacer element to the first surface of the third spacer element, and CP3 is the maximum thickness of the third spacer element. By reasonably configuring the visual optical system and controlling R6 / tan(β1.0) and f / (EP13 + CP3) within a reasonable range, the angle of the light passing through the first quarter-wave plate and the reflective polarizing element attached to the second lens is close to parallel, which can effectively reduce the reflection of excess light, thereby reducing the polarization angle effect, reducing the ghost image formed by the light directly passing through the reflective polarizing element and reaching the human eye, and improving the imaging quality.

[0067] Fig.15 The ghost image effect diagram of the visual optical system of the present application when satisfying R6 / tan(β 1.0 ) = -13.54 mm and f / (EP13 + CP3) = 2.16 is shown. Fig.15 The visual optical system in satisfies the range defined by the conditional expressions R6 / tan(β1.0) and f / (EP13 + CP3) of the present application. As can be seen from Fig.15 , the ghost image of the direct path is greatly reduced, and the ratio of the power of the direct path to the power of the main path is 0.8%. The ghost image effect of the visual optical system is good.

[0068] Fig.16 The ghost image effect diagram of the visual optical system of the present application when satisfying R6 / tan(β 1.0 ) = -15 mm and f / (EP13 + CP3) = 1.5 is shown. Fig.16 The visual optical system in exceeds the lower limit of the range defined by the conditional expressions R6 / tan(β1.0) and f / (EP13 + CP3) of the present application. As can be seen from Fig.16 , the ghost image of the direct path is large, and the ratio of the power of the direct path to the power of the main path is 5.5%. The ghost image effect of the visual optical system is poor.

[0069] Fig.17 The ghost image effect diagram of the visual optical system of the present application when satisfying R6 / tan(β 1.0 ) = -10 mm and f / (EP13 + CP3) = 2.8 is shown. Fig.17 The visual optical system in exceeds the upper limit of the range defined by the conditional expressions R6 / tan(β1.0) and f / (EP13 + CP3) of the present application. As can be seen from Fig.17 It can be seen that the ghost image of the direct optical path is relatively large, and the ratio of the power of the direct optical path to the power of the main optical path is 2.75%, and the ghost image effect of the visual optical system is relatively poor.

[0070] It should be noted that the above-mentioned direct optical path can be an optical path formed by light directly passing through the reflective polarizing element, and the main optical path can be an optical path formed by light being reflected twice by the reflective polarizing element and the partial reflection element.

[0071] In an exemplary embodiment, the visual optical system satisfies: 1.25 ≤ (d1m + D1m) / fz1 ≤ 1.46, where d1m is the inner diameter of the second side surface of the first spacer element, D1m is the outer diameter of the second side surface of the first spacer element, and fz1 is the combined focal length of the reflective polarizing element, the first quarter-wave plate, and the second lens. By controlling the above conditions, on the one hand, the imaging quality of the system can be ensured to be good, and on the other hand, on the basis of ensuring the supporting effect of the first spacer element, it is beneficial to improve the stability of the erection of the first lens group.

[0072] In an exemplary embodiment, the visual optical system satisfies: 3.5 < (CTR + CTQ1 + CT2) / CP1 < 6.65, where CTR is the central thickness of the reflective polarizing element on the optical axis, CTQ1 is the central thickness of the first quarter-wave plate on the optical axis, CT2 is the central thickness of the second lens on the optical axis, and CP1 is the maximum thickness of the first spacer element. By controlling the above conditions, it is beneficial to the miniaturization of the system and optimizes the processability of the attachment between the reflective polarizing element, the first quarter-wave plate, and the second lens.

[0073] In an exemplary embodiment, the visual optical system satisfies: -2.5 < fz2 / D0m < -2.2, where fz2 is the combined focal length of the fourth lens, the second quarter-wave plate, and the polarizer, and D0m is the outer diameter of the second end face of the lens barrel. By controlling the above conditions, it is beneficial to achieve a short-focus wide-angle design within the distance from the center of the first side surface of the limited first lens to the image plane of the system on the optical axis, and it can reasonably distribute the optical power, which is beneficial to ensuring the optical performance of the system.

[0074] In an exemplary embodiment, the visual optical system satisfies: 2.5 < EP13 / T23 < 3.0, where EP13 is the distance along the optical axis from the second side surface of the first spacer element to the first side surface of the third spacer element, and T23 is the distance on the optical axis from the second side surface of the second lens to the first side surface of the third lens. By controlling the above conditions, the system reaches the most suitable forming structure and erection stability.

[0075] In an exemplary embodiment, the visual optical system satisfies: 4.19 mm ≤ d3s / tan(β 0.8) ≤ 5.05 mm, where d3s is the inner diameter of the first side surface of the third spacer element, and β 0.8 is the angle between the tangent line and the optical axis at the intersection position of the chief ray of the 0.8 field of view after being reflected by the partial reflection element and the second side surface of the third lens. By controlling the above conditions, the field of view angle of the system is effectively constrained, the amount of incident light can be effectively controlled, the generation of stray light can be reduced, and the imaging clarity can be improved.

[0076] In an exemplary embodiment, the visual optical system satisfies: 6.65 < (D1s / d1s) * tan(β 0.9 ) < 6.85, where D1s is the outer diameter of the first side surface of the first spacer element, d1s is the inner diameter of the first side surface of the first spacer element, and β 0.9 is the angle between the tangent line and the optical axis at the intersection position of the chief ray of the 0.9 field of view after being reflected by the partial reflection element and the second side surface of the third lens. By controlling the above conditions, it helps to control the contact area between the second side surface of the first spacer element and the adjacent element, improve the assembly stability, block the redundant light, and improve the stray light phenomenon of the system.

[0077] In an exemplary embodiment, the visual optical system satisfies: 0.95 < (d0s + D0s) / f1 < 1.4, where d0s is the inner diameter of the first side end surface of the lens barrel, D0s is the outer diameter of the first side end surface of the lens barrel, and f1 is the effective focal length of the first lens. By controlling the above conditions, the inner and outer diameters of the first side end surface of the lens barrel can be restricted, the amount of incident light can be effectively controlled, and the light can be utilized more efficiently to participate in imaging.

[0078] In an exemplary embodiment, the visual optical system satisfies: 0.85 < CT1 / EP01 < 1.7, where CT1 is the central thickness of the first lens on the optical axis, and EP01 is the distance between the first side end surface of the lens barrel and the first side surface of the first spacer element along the optical axis. By controlling the above conditions, the ratio of the central thickness to the edge thickness of the first lens can be ensured, which is beneficial to the molding and assembly of the first lens.

[0079] In an exemplary embodiment, the visual optical system satisfies: 2.70 ≤ f2 / L ≤ 3.43, where f2 is the effective focal length of the second lens, and L is the distance between the first side end surface of the lens barrel and the second side end surface of the lens barrel along the optical axis. By controlling the above conditions, the optical power of the second lens can be reasonably distributed, the maximum field of view angle of the system can be indirectly controlled, and it is beneficial to realize the reasonable arrangement of the lens barrel structure.

[0080] In an exemplary embodiment, the visual optical system satisfies: 1.15 < f3 / f4 < 1.25 and 1.0 < D3m / d3m < 1.25, where f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, D3m is the outer diameter of the second side surface of the third spacer element, and d3m is the inner diameter of the second side surface of the third spacer element. Under the condition of 1.15 < f3 / f4 < 1.25, by controlling D3m / d3m within a suitable range, the volume of the visual optical system can be reduced, which is beneficial to improving the assembly stability, and further helps to achieve the light weight of the optical device.

[0081] In an exemplary embodiment, the visual optical system satisfies: -1.85 < R7 / D3s < -1.5, where R7 is the radius of curvature of the first side surface of the fourth lens, and D3s is the outer diameter of the first side surface of the third spacer element. By controlling the above conditions, the sensitivity of the fourth lens can be effectively reduced, thereby improving the assembly yield.

[0082] In an exemplary embodiment, the visual optical system satisfies: 1.74 ≤ d0m / TD ≤ 2.51, where d0m is the inner diameter of the second side end surface of the lens barrel, and TD is the distance on the optical axis from the first side surface of the first lens to the second side surface of the fourth lens. By controlling the above conditions, the outer dimension of the lens barrel is indirectly restricted, thereby reducing the size of the system.

[0083] In an exemplary embodiment, the visual optical system satisfies: 0.9 < R1 / d0s < 1.0, where R1 is the radius of curvature of the first side surface of the first lens, and d0s is the inner diameter of the first side end surface of the lens barrel. By controlling the above conditions, the outer shape of the first side surface of the first lens can be restricted, which is beneficial to reducing the sensitivity of the first lens, thereby improving the assembly yield. At the same time, by controlling the inner diameter dimension of the first side end surface of the lens barrel, the generation of stray light can be reduced, and the imaging clarity can be improved.

[0084] Another aspect of the present application provides a visual optical system, which includes a lens barrel and an optical element group and a spacing element group contained in the lens barrel, wherein the optical element group includes, in order from the first side to the second side along the optical axis: a first lens with positive optical power, whose first side surface is a convex surface; a reflective polarizing element; a first quarter wave plate; a second lens with positive optical power, whose first side surface is a plane and whose second side surface is a convex surface; a third lens with negative optical power, whose first side surface is a concave surface and whose second side surface is a convex surface; a partial reflecting element; a fourth lens with negative optical power, whose first side surface is a concave surface and whose second side surface is a plane; a second quarter wave plate; a polarizing plate; wherein the number of lenses with optical power in the optical element group is four; the spacing element group includes a first spacing element and a third spacing element, the first spacing element is located between the first lens and the second lens and contacts the second side surface of the first lens, the third spacing element is located between the third lens and the fourth lens and contacts the second side surface of the third lens; and the visual optical system satisfies: -14.05mm≤R6 / tan(β 1.0 )≤-11.86mm and 6.65<(D1s / d1s)*tan(β 0.9 )<6.85, wherein R6 is the radius of curvature of the second side surface of the third lens, D1s is the outer diameter of the first side surface of the first spacing element, d1s is the inner diameter of the first side surface of the first spacing element, β 0.9 is the angle between the tangent line at the intersection of the principal ray and the second side surface of the third lens at the time of reflection and the optical axis under the field of view of 0.9, β 1.0 It is the angle between the tangent line of the intersection of the main light and the second side surface of the third lens at the time of reflection and the optical axis under the field of view of 1.0. By setting the reflective polarizing element, the first quarter wave plate, the partial reflective element, etc., the light can be refracted multiple times between the first lens and the fourth lens, and the optical path can be folded under the premise of ensuring the imaging quality, effectively shortening the main body length of the visual optical system, and by controlling the above conditions, it is helpful to control the bearing area of ​​the second side surface of the first spacing element and the adjacent element, improve the assembly stability, block excess light, and improve the stray light phenomenon of the system.

[0085] In an embodiment of the present application, at least one of the surfaces of the first lens, the second lens, the third lens, and the fourth lens is an aspherical surface. The characteristic of an aspherical lens is that the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. After adopting an aspherical lens, the aberration occurring during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0086] Those skilled in the art should understand that, without departing from the technical solution claimed in the present application, the number of lenses and other elements constituting the visual optical system can be changed to obtain the various results and advantages described in this specification.

[0087] The following further describes a specific embodiment of the visual optical system applicable to the above-mentioned embodiment with reference to the accompanying drawings. Figures 3 to 6 Describe the visual optical system according to Embodiment 1 to Embodiment 3 of the present application; refer to Figures 7 to 10 Describe the visual optical system according to Embodiment 4 to Embodiment 6 of the present application; refer to Figures 11 to 14 The visual optical systems according to Embodiments 7 to 9 of the present application are described.

[0088] Example 1

[0089] Figure 3 FIG. 1 shows a schematic diagram of the structure of the visual optical system of Example 1 of the present application. Figure 3 As shown, the visual optical system includes a lens barrel P0, an optical element group and a spacer element group arranged in the lens barrel P0.

[0090] The optical element group includes, 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, a fourth lens E4, a second quarter wave plate QWP2, and a polarizing plate LP. The aperture STO may be located on the first side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side.

[0091] The first lens E1 has positive focal power, and its first side surface S1 is convex, and its second side surface S2 is concave and thin Fresnel surface. The second lens E2 has positive focal power, and its first side surface S3 is a plane, and its second side surface S4 is a convex surface. The third lens E3 has negative focal power, and its first side surface S5 is a concave surface, and its second side surface S6 is a convex surface. The fourth lens E4 has negative focal power, and its first side surface S7 is a concave surface, and its second side surface S8 is a plane. The first quarter wave plate QWP1 is located on the first side of the second lens E2. The second quarter wave plate QWP2 is located on the second side of the fourth lens E4. The reflective polarizing element RP is located on the first side of the first quarter wave plate QWP1. The polarizing plate LP is located on the second side of the second quarter wave plate QWP2. Among them, the second lens E2, the first quarter wave plate QWP1 and the reflective polarizing element RP form a cemented lens with positive focal power; the fourth lens E4, the second quarter wave plate QWP2 and the polarizing plate LP form a cemented lens with negative focal power. The partial reflection element BS is located between the third lens E3 and the fourth lens E4, and is attached to the second side surface S6 of the third lens E3. Figure 3Not shown in FIG.

[0092] The spacer element is located between the non-effective diameter regions of the optical element group, and the spacer element group includes a first spacer element P1 and a third spacer element P3. The first spacer element P1 is located between the first lens E1 and the second lens E2 and contacts the second side surface S2 of the first lens E1, and the third spacer element P3 is located between the third lens E3 and the fourth lens E4 and contacts the second side surface S6 of the third lens E3.

[0093] In this example, an image surface IMG (not shown) may be provided on the second side of the visual optical system, and the image surface IMG may be provided with a display screen, for example. The image light from the image surface IMG enters the human eye (not shown) after being refracted multiple times by the visual optical system. Specifically, the image light from the image surface IMG sequentially passes through the polarizer LP, the second quarter wave plate QWP2, the fourth lens E4, the partial reflection element BS, the third lens E3, the second lens E2, the first quarter wave plate QWP1, and is reflected for the first time at the reflective polarizing element RP. The first reflected light sequentially passes through the first quarter wave plate QWP1, the second lens E2, and the third lens E3, and then is reflected for the second time at the partial reflection element BS. The secondary reflected 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 is finally projected to the human eye.

[0094] Table 1 shows the basic parameters of each component of the visual optical system of Example 1, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm). The image light from the image surface IMG passes through each component in the order of sequence number 22 to sequence number 0 and is finally projected to the human eye.

[0095] Table 1

[0096]

[0097] In this embodiment, the first side surface S1 and the second side surface S2 of the first lens E1, 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 E3, and the first side surface S7 of the fourth lens E4 are all aspherical surfaces. The surface shape of each aspherical lens can be defined by but not limited to the following aspherical surface formula:

[0098]

[0099] Wherein, x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c=1 / R (i.e., the paraxial curvature c is the reciprocal of the curvature radius R in Table 1 above); k is the cone coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. Table 2 shows the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 of the aspheric surface of each lens that can be used in Example 1.

[0100] Table 2

[0101] Face number A4 A6 A8 A10 A12 A14 A16 A18 A20 S1 -2.9124E-05 9.6886E-08 -4.0238E-11 -1.7257E-12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S2 -4.7713E-05 -1.1797E-07 1.3744E-09 -5.4518E-12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S4 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S5 -2.2544E-05 1.4309E-08 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S6 3.0387E-06 2.2672E-08 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S7 1.6813E-05 4.8840E-08 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0102] Example 2

[0103] Figure 4 FIG. 2 shows a schematic diagram of the structure of the visual optical system of Example 2 of the present application. Figure 4 As shown, the visual optical system includes a lens barrel P0, an optical element group and a spacer element group arranged in the lens barrel P0.

[0104] The optical element group includes, 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, a fourth lens E4, a second quarter wave plate QWP2, and a polarizing plate LP. The aperture STO may be located on the first side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side.

[0105] The structure of the optical element group of the visual optical system of this embodiment is the same as that of the optical element group of the visual optical system in Embodiment 1. The basic parameters thereof are detailed in Tables 1 and 2 and will not be described in detail.

[0106] The difference between this embodiment and the first embodiment is that the lens barrel P0 and at least some elements in the spacer element group have different structural dimensions.

[0107] Example 3

[0108] Figure 5 FIG. 2 shows a schematic diagram of the structure of the visual optical system of Example 3 of the present application. Figure 5 As shown, the visual optical system includes a lens barrel P0, an optical element group and a spacer element group arranged in the lens barrel P0.

[0109] The optical element group includes, 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, a fourth lens E4, a second quarter wave plate QWP2, and a polarizing plate LP. The aperture STO may be located on the first side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side.

[0110] The structure of the optical element group of the visual optical system of this embodiment is the same as that of the optical element group of the visual optical system in Embodiment 1. The basic parameters thereof are detailed in Tables 1 and 2 and will not be described in detail.

[0111] The difference between this embodiment and the first embodiment is that the lens barrel P0 and at least some elements in the spacer element group have different structural dimensions.

[0112] Figure 6 The MTF curves of the visual optical systems of Examples 1 to 3 are shown. The visual optical systems provided by Examples 1 to 3 can achieve good imaging quality.

[0113] Example 4

[0114] Figure 7 FIG. 4 shows a schematic diagram of the structure of the visual optical system of Example 4 of the present application. Figure 7 As shown, the visual optical system includes a lens barrel P0, an optical element group and a spacer element group arranged in the lens barrel P0.

[0115] The optical element group includes, 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, a fourth lens E4, a second quarter wave plate QWP2, and a polarizing plate LP. The aperture STO may be located on the first side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side.

[0116] The first lens E1 has positive focal power, and its first side surface S1 is convex, and the second side surface S2 is convex and a thin Fresnel surface. The second lens E2 has positive focal power, and its first side surface S3 is a plane, and the second side surface S4 is a convex surface. The third lens E3 has negative focal power, and its first side surface S5 is a concave surface, and the second side surface S6 is a convex surface. The fourth lens E4 has negative focal power, and its first side surface S7 is a concave surface, and the second side surface S8 is a plane. The first quarter wave plate QWP1 is located on the first side of the second lens E2. The second quarter wave plate QWP2 is located on the second side of the fourth lens E4. The reflective polarizing element RP is located on the first side of the first quarter wave plate QWP1. The polarizing plate LP is located on the second side of the second quarter wave plate QWP2. Among them, the second lens E2, the first quarter wave plate QWP1 and the reflective polarizing element RP form a cemented lens with positive focal power; the fourth lens E4, the second quarter wave plate QWP2 and the polarizing plate LP form a cemented lens with negative focal power. The partial reflection element BS is located between the third lens E3 and the fourth lens E4, and is attached to the second side surface S6 of the third lens E3. Figure 7 Not shown in FIG.

[0117] The spacer element is located between the non-effective diameter regions of the optical element group, and the spacer element group includes a first spacer element P1 and a third spacer element P3. The first spacer element P1 is located between the first lens E1 and the second lens E2 and contacts the second side surface S2 of the first lens E1, and the third spacer element P3 is located between the third lens E3 and the fourth lens E4 and contacts the second side surface S6 of the third lens E3.

[0118] In this example, an image surface IMG (not shown) may be provided on the second side of the visual optical system, and the image surface IMG may be provided with a display screen, for example. The image light from the image surface IMG enters the human eye (not shown) after being refracted multiple times by the visual optical system. Specifically, the image light from the image surface IMG sequentially passes through the polarizer LP, the second quarter wave plate QWP2, the fourth lens E4, the partial reflection element BS, the third lens E3, the second lens E2, the first quarter wave plate QWP1, and is reflected for the first time at the reflective polarizing element RP. The first reflected light sequentially passes through the first quarter wave plate QWP1, the second lens E2, and the third lens E3, and then is reflected for the second time at the partial reflection element BS. The secondary reflected 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 is finally projected to the human eye.

[0119] Table 3 shows the basic parameters of each component of the visual optical system of Example 4, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm). The image light from the image surface IMG passes through each component in the order of sequence number 22 to sequence number 0 and is finally projected to the human eye.

[0120] Table 3

[0121]

[0122]

[0123] In this embodiment, the first side surface S1 and the second side surface S2 of the first lens E1, 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 E3, and the first side surface S7 of the fourth lens E4 are all aspherical surfaces. Table 4 lists the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 of the aspherical surfaces of the lenses that can be used in Embodiment 4.

[0124] Table 4

[0125] Face number A4 A6 A8 A10 A12 A14 A16 A18 A20 S1 5.5695E-05 -2.5404E-07 7.0704E-10 -7.2962E-13 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S2 -3.3652E-06 4.9964E-08 -5.8558E-10 1.4678E-12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S4 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S5 1.0551E-05 -1.1516E-08 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S6 2.3009E-06 6.8515E-10 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S7 4.3216E-06 4.5400E-08 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0126] Example 5

[0127] Figure 8 FIG. 5 shows a schematic diagram of the structure of the visual optical system of Example 5 of the present application. Figure 8 As shown, the visual optical system includes a lens barrel P0, an optical element group and a spacer element group arranged in the lens barrel P0.

[0128] The optical element group includes, 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, a fourth lens E4, a second quarter wave plate QWP2, and a polarizing plate LP. The aperture STO may be located on the first side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side.

[0129] The structure of the optical element group of the visual optical system of this embodiment is the same as that of the optical element group of the visual optical system in Embodiment 4. The basic parameters thereof are detailed in Tables 3 and 4 and will not be described in detail.

[0130] The difference between this embodiment and Embodiment 4 is that the lens barrel P0 and at least some elements in the spacer element group have different structural dimensions.

[0131] Example 6

[0132] Fig. 9 FIG. 6 shows a schematic diagram of the structure of the visual optical system of Example 6 of the present application. Fig. 9 As shown, the visual optical system includes a lens barrel P0, an optical element group and a spacer element group arranged in the lens barrel P0.

[0133] The optical element group includes, 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, a fourth lens E4, a second quarter wave plate QWP2, and a polarizing plate LP. The aperture STO may be located on the first side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side.

[0134] The structure of the optical element group of the visual optical system of this embodiment is the same as that of the optical element group of the visual optical system in Embodiment 4. The basic parameters thereof are detailed in Tables 3 and 4 and will not be described in detail.

[0135] The difference between this embodiment and Embodiment 4 is that the lens barrel P0 and at least some elements in the spacer element group have different structural dimensions.

[0136] Fig.10 The MTF curves of the visual optical systems of Examples 4 to 6 are shown. The visual optical systems provided by Examples 4 to 6 can achieve good imaging quality.

[0137] Example 7

[0138] Fig.11 FIG. 2 shows a schematic diagram of the structure of the visual optical system of Example 7 of the present application. Fig.11 As shown, the visual optical system includes a lens barrel P0, an optical element group and a spacer element group arranged in the lens barrel P0.

[0139] The optical element group includes, 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, a fourth lens E4, a second quarter wave plate QWP2, and a polarizing plate LP. The aperture STO may be located on the first side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side.

[0140] The first lens E1 has positive focal power, and its first side surface S1 is convex, and the second side surface S2 is convex and a thin Fresnel surface. The second lens E2 has positive focal power, and its first side surface S3 is a plane, and the second side surface S4 is a convex surface. The third lens E3 has negative focal power, and its first side surface S5 is a concave surface, and the second side surface S6 is a convex surface. The fourth lens E4 has negative focal power, and its first side surface S7 is a concave surface, and the second side surface S8 is a plane. The first quarter wave plate QWP1 is located on the first side of the second lens E2. The second quarter wave plate QWP2 is located on the second side of the fourth lens E4. The reflective polarizing element RP is located on the first side of the first quarter wave plate QWP1. The polarizing plate LP is located on the second side of the second quarter wave plate QWP2. Among them, the second lens E2, the first quarter wave plate QWP1 and the reflective polarizing element RP form a cemented lens with positive focal power; the fourth lens E4, the second quarter wave plate QWP2 and the polarizing plate LP form a cemented lens with negative focal power. The partial reflection element BS is located between the third lens E3 and the fourth lens E4, and is attached to the second side surface S6 of the third lens E3. Fig.11 Not shown.

[0141] The spacer element is located between the non-effective diameter regions of the optical element group, and the spacer element group includes a first spacer element P1 and a third spacer element P3. The first spacer element P1 is located between the first lens E1 and the second lens E2 and contacts the second side surface S2 of the first lens E1, and the third spacer element P3 is located between the third lens E3 and the fourth lens E4 and contacts the second side surface S6 of the third lens E3.

[0142] In this example, an image surface IMG (not shown) may be provided on the second side of the visual optical system, and the image surface IMG may be provided with a display screen, for example. The image light from the image surface IMG enters the human eye (not shown) after being refracted multiple times by the visual optical system. Specifically, the image light from the image surface IMG sequentially passes through the polarizer LP, the second quarter wave plate QWP2, the fourth lens E4, the partial reflection element BS, the third lens E3, the second lens E2, the first quarter wave plate QWP1, and is reflected for the first time at the reflective polarizing element RP. The first reflected light sequentially passes through the first quarter wave plate QWP1, the second lens E2, and the third lens E3, and then is reflected for the second time at the partial reflection element BS. The secondary reflected 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 is finally projected to the human eye.

[0143] Table 5 shows the basic parameters of each component of the visual optical system of Example 7, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm). The image light from the image surface IMG passes through each component in the order of sequence number 22 to sequence number 0 and is finally projected to the human eye.

[0144] Table 5

[0145]

[0146] In this embodiment, the first side surface S1 and the second side surface S2 of the first lens E1, 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 E3, and the first side surface S7 of the fourth lens E4 are all aspherical surfaces. Table 6 lists the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 of the aspherical surfaces of the lenses that can be used in Example 7.

[0147] Table 6

[0148] Face number A4 A6 A8 A10 A12 A14 A16 A18 A20 S1 -1.4482E-06 -1.3705E-08 8.0634E-11 -1.4173E-13 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S2 -8.0448E-06 -6.3277E-10 1.4079E-12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S4 1.0626E-06 -1.0563E-08 1.8843E-11 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S5 -1.2222E-05 4.7479E-09 -1.2787E-11 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S6 1.6958E-06 2.1092E-09 6.8434E-13 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S7 4.8535E-06 1.6296E-08 1.0454E-11 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0149] Example 8

[0150] Fig.12 FIG. 8 is a schematic diagram showing the structure of the visual optical system of Example 8 of the present application. Fig.12 As shown, the visual optical system includes a lens barrel P0, an optical element group and a spacer element group arranged in the lens barrel P0.

[0151] The optical element group includes, 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, a fourth lens E4, a second quarter wave plate QWP2, and a polarizing plate LP. The aperture STO may be located on the first side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side.

[0152] The optical element group of the visual optical system of this embodiment has the same structure as the optical element group of the visual optical system in Example 7. Its basic parameters are detailed in Tables 5 and 6 and will not be described in detail.

[0153] The difference between this embodiment and Embodiment 7 is that the lens barrel P0 and at least some elements in the spacer element group have different structural dimensions.

[0154] Example 9

[0155] Fig.13 FIG. 1 shows a schematic diagram of the structure of the visual optical system of Example 9 of the present application. Fig.13As shown, the visual optical system includes a lens barrel P0, an optical element group and a spacer element group arranged in the lens barrel P0.

[0156] The optical element group includes, 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, a fourth lens E4, a second quarter wave plate QWP2, and a polarizing plate LP. The aperture STO may be located on the first side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side.

[0157] The optical element group of the visual optical system of this embodiment has the same structure as the optical element group of the visual optical system in Example 7. Its basic parameters are detailed in Tables 5 and 6 and will not be described in detail.

[0158] The difference between this embodiment and Embodiment 7 is that the lens barrel P0 and at least some elements in the spacer element group have different structural dimensions.

[0159] Fig.14 The MTF curves of the visual optical systems of Examples 7 to 9 are shown. The visual optical systems provided by Examples 7 to 9 can achieve good imaging quality.

[0160] Table 7 shows f, f1, f2, f3, f4, fz1, fz2, CTR, CTQ1, TD, β of each embodiment in Embodiment 1 to Embodiment 9. 0.8 , β 0.9 , β 1.0 Parameter value.

[0161] Table 7

[0162]

[0163] Table 8 gives the values ​​of parameters of at least some elements in the lens barrel P0 and the spacer element group in each embodiment from Embodiment 1 to Embodiment 9. Among them, some parameters can be calculated according to Figure 1 The parameters listed in Table 8 are measured using the marking method shown in the figure, and the units of the parameters listed in Table 8 are all millimeters (mm).

[0164] Table 8

[0165] Parameters / Examples 1 2 3 4 5 6 7 8 9 d1s 34.357 34.179 33.684 34.164 34.372 34.588 38.433 38.662 38.007 d1m 34.309 34.250 33.991 34.722 34.838 34.900 38.148 38.345 37.969 D1s 35.304 35.094 34.690 35.610 35.227 35.325 39.978 39.682 39.386 D1m 35.059 35.111 34.729 35.312 35.266 36.023 39.195 39.687 39.420 d3s 29.282 29.405 33.258 34.683 34.494 31.173 35.980 35.868 35.819 d3m 29.282 29.405 32.846 34.614 34.472 31.173 35.379 35.639 35.554 D3s 36.295 36.295 34.647 35.523 35.307 37.069 37.253 36.989 36.889 D3m 36.295 36.295 35.066 35.956 35.774 37.069 36.560 36.373 36.708 d0s 36.914 36.914 37.087 39.454 39.454 39.361 44.943 44.508 44.367 d0m 36.866 37.072 37.246 39.735 39.304 39.094 34.774 34.441 34.980 D0s 38.314 38.695 38.695 41.184 41.184 40.744 47.020 46.505 46.004 D0m 38.601 38.981 38.981 41.470 41.470 41.031 40.376 39.747 40.613 EP01 1.657 1.657 1.700 2.785 3.247 3.059 6.672 6.562 6.672 CP1 1.188 0.961 1.188 1.485 1.102 1.485 1.054 0.938 1.054 EP13 7.903 8.231 7.903 7.492 7.492 8.020 8.213 8.329 8.213 CP3 0.100 0.100 0.837 1.295 0.929 0.100 1.156 1.156 0.830 L 14.593 14.510 14.452 16.514 16.353 16.341 20.927 20.817 20.785

[0166] In summary, the visual optical systems in Examples 1 to 9 satisfy the relationship shown in Table 9.

[0167] Table 9

[0168] Conditional / Example 1 2 3 4 5 6 7 8 9 <![CDATA[R6 / tan(β 1.0 )]]> -11.86 -11.86 -11.86 -13.54 -13.54 -13.54 -14.05 -14.05 -14.05 f / (EP13+CP3) 2.21 2.12 2.02 2.16 2.25 2.33 2.17 2.15 2.25 (d1m+D1m) / fz1 1.46 1.46 1.44 1.25 1.25 1.27 1.37 1.38 1.37 (CTR+CTQ1+CT2) / CP1 4.80 5.94 4.80 3.54 4.77 3.54 5.90 6.63 5.90 <![CDATA[d3s / tan(β 0.8 )]]> 4.19 4.21 4.76 4.81 4.78 4.32 5.05 5.04 5.03 (d0s+D0s) / f1 0.98 0.99 0.99 1.37 1.37 1.36 1.25 1.24 1.23 fz2 / D0m -2.24 -2.22 -2.22 -2.45 -2.45 -2.47 -2.46 -2.49 -2.44 CT1 / EP01 1.68 1.68 1.64 1.59 1.37 1.45 0.87 0.88 0.87 f2 / L 3.26 3.28 3.29 3.39 3.43 3.43 2.70 2.71 2.72 f3 / f4 1.17 1.17 1.17 1.16 1.16 1.16 1.22 1.22 1.22 D3m / d3m 1.24 1.23 1.07 1.04 1.04 1.19 1.03 1.02 1.03 <![CDATA[(D1s / d1s)*tan(β 0.9 )]]> 6.68 6.67 6.69 6.81 6.69 6.67 6.78 6.69 6.75 R7 / D3s -1.53 -1.53 -1.61 -1.83 -1.84 -1.76 -1.72 -1.73 -1.73 d0m / TD 2.48 2.50 2.51 2.30 2.28 2.27 1.76 1.74 1.77 EP13 / T23 2.86 2.97 2.86 2.53 2.53 2.70 2.78 2.82 2.78 R1 / d0s 0.93 0.93 0.93 0.95 0.95 0.96 0.92 0.93 0.93

[0169] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a 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 inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other.

Claims

1. A visual optical system, characterized in that: Comprising: An optical element group, which sequentially includes, along the optical axis from the first side to the second side: A first lens with a positive optical power, whose first side is convex; A reflective polarizing element; A first quarter-wave plate; A second lens with a positive optical power, whose first side is flat and the second side is convex; A third lens with a negative optical power, whose first side is concave and the second side is convex; A partial reflection element; A fourth lens with a negative optical power, whose first side is concave and the second side is flat; A second quarter-wave plate; A polarizer; Wherein, the number of lenses with optical power in the optical element group is four; A spacer element group, including a first spacer element and a third spacer element. The first spacer element is located between the first lens and the second lens and is in contact with the second side of the first lens. The third spacer element is located between the third lens and the fourth lens and is in contact with the second side of the third lens; A lens barrel for accommodating the optical element group and the spacer element group; and The visual optical system satisfies: -14.05mm≤R6 / tan(β 1.0 )≤-11.86mm and 2.0 <f / (EP13+CP3)<2.35; Wherein, R6 is the radius of curvature of the second side surface of the third lens, β 1.0 is the angle between the tangent of the second side surface of the third lens at the intersection of the main light of 1.0 field of view after reflection by the partial reflecting element and the optical axis, f is the total effective focal length of the visual optical system, EP13 is the distance from the second side surface of the first spacing element to the first side surface of the third spacing element along the optical axis, and CP3 is the maximum thickness of the third spacing element.

2. The visual optical system according to claim 1, characterized in that: The visual optical system satisfies: 1.25 ≤ (d1m + D1m) / fz1 ≤ 1.46, where d1m is the inner diameter of the second side of the first spacer element, D1m is the outer diameter of the second side of the first spacer element, and fz1 is the combined focal length of the reflective polarizing element, the first quarter-wave plate, and the second lens.

3. The visual optical system according to claim 1, characterized in that: The visual optical system satisfies: 3.5 < (CTR + CTQ1 + CT2) / CP1 < 6.65, where CTR is the central thickness of the reflective polarizing element on the optical axis, CTQ1 is the central thickness of the first quarter-wave plate on the optical axis, CT2 is the central thickness of the second lens on the optical axis, and CP1 is the maximum thickness of the first spacer element.

4. The visual optical system according to claim 1, characterized in that: The visual optical system satisfies: -2.5 < fz2 / D0m < -2.2, where fz2 is the combined focal length of the fourth lens, the second quarter-wave plate, and the polarizer, and D0m is the outer diameter of the second side end face of the lens barrel.

5. The visual optical system according to claim 1, characterized in that: The visual optical system satisfies: 2.5 < EP13 / T23 < 3.0, where T23 is the distance on the optical axis from the second side of the second lens to the first side of the third lens.

6. The visual optical system according to any one of claims 1 to 5, characterized in that: The visual optical system satisfies: 4.19mm≤d3s / tan(β 0.8 )≤5.05mm, wherein d3s is the inner diameter of the first side of the third spacing element, β 0.8 is the angle between the tangent line of the second side surface of the third lens at the intersection of the principal light of 0.8 field of view after being reflected by the partial reflective element and the optical axis.

7. The visual optical system according to any one of claims 1 to 5, characterized in that: The visual optical system satisfies: 6.65<(D1s / d1s)*tan(β 0.9 )<6.85, wherein D1s is the outer diameter of the first side surface of the first spacing element, d1s is the inner diameter of the first side surface of the first spacing element, and β 0.9 is the angle between the tangent line of the second side surface of the third lens at the intersection of the principal light of 0.9 field of view after being reflected by the partial reflective element and the optical axis.

8. The visual optical system according to any one of claims 1 to 5, characterized in that: The visual optical system satisfies: 0.95 < (d0s + D0s) / f1 < 1.4, where d0s is the inner diameter of the first side end face of the lens barrel, D0s is the outer diameter of the first side end face of the lens barrel, and f1 is the effective focal length of the first lens.

9. The visual optical system according to any one of claims 1 to 5, characterized in that: The visual optical system satisfies: 0.85 < CT1 / EP01 < 1.7, where CT1 is the central thickness of the first lens on the optical axis, and EP01 is the distance in the optical axis direction between the first side end face of the lens barrel and the first side of the first spacer element.

10. The visual optical system according to any one of claims 1 to 5, characterized in that: The visual optical system satisfies: 2.70 ≤ f2 / L ≤ 3.43, where f2 is the effective focal length of the second lens, and L is the distance in the optical axis direction from the first side end face of the lens barrel to the second side end face of the lens barrel.

11. The visual optical system according to any one of claims 1 to 5, characterized in that: The visual optical system satisfies: 1.15 < f3 / f4 < 1.25 and 1.0 < D3m / d3m < 1.25, where f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, D3m is the outer diameter of the second side surface of the third spacer element, and d3m is the inner diameter of the second side surface of the third spacer element.

12. The visual optical system according to any one of claims 1 to 5, characterized in that: The visual optical system satisfies: -1.85 < R7 / D3s < -1.5, where R7 is the radius of curvature of the first side surface of the fourth lens, and D3s is the outer diameter of the first side surface of the third spacer element.

13. The visual optical system according to any one of claims 1 to 5, characterized in that: The visual optical system satisfies: 1.74 ≤ d0m / TD ≤ 2.51, where d0m is the inner diameter of the second end surface of the lens barrel, and TD is the distance on the optical axis from the first side surface of the first lens to the second side surface of the fourth lens.

14. The visual optical system according to any one of claims 1 to 5, characterized in that: The visual optical system satisfies: 0.9 < R1 / d0s < 1.0, where R1 is the radius of curvature of the first side surface of the first lens, and d0s is the inner diameter of the first end surface of the lens barrel.

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