Visual optical system and virtual reality display device

Abstract

A visual optical system and a virtual reality display device, wherein the visual optical system comprises, in sequence from the side of a human eye to the side of a display screen along an optical axis: a first lens with positive refractive power, an out-coupling surface of which is a convex surface, and an in-coupling surface of which is sequentially attached with a reflective polarizing element and a quarter-wave plate; and a second lens with positive refractive power, an in-coupling surface of which is a convex surface, and an out-coupling surface of which is a convex surface; wherein the out-coupling surface of the first lens or the out-coupling surface of the second lens is a Fresnel surface; an on-axis distance TTL from the out-coupling surface of the first lens to the display screen, a central thickness CT1 of the first lens, a central thickness CT2 of the second lens, a curvature radius R3 of the out-coupling surface of the second lens, and a curvature radius R4 of the in-coupling surface of the second lens satisfy the following conditional expressions: 1.5 < TTL / (CT1+CT2) < 2.6; and -2.0 < R4 / R3 < 0.

Description

Technical Field

[0001] This application relates to the field of optical imaging, and more specifically, to a visual optical system including two lenses and a virtual reality display device. Background Technology

[0002] In recent years, virtual reality (VR) display technology has been increasingly widely used in education, healthcare, and consumer fields. VR display devices can simulate virtual environments, thereby providing users with an immersive experience in terms of sight, hearing, and touch.

[0003] The visual optical system is a crucial component of VR display devices, and its image quality and field of view directly impact the user experience. Simultaneously, the size of the visual optical system directly influences the overall size of the VR display device. Current VR display devices, in an effort to reduce size while maintaining good imaging performance, typically employ a combination of multiple aspherical lenses. However, this approach reduces production yield, increases manufacturing costs, and results in longer optical components, thus leading to a larger overall device size.

[0004] Therefore, there is a need for a visual optical system that can meet the user's high experience requirements, while reducing size, ensuring external field of view performance and improving image quality. Summary of the Invention

[0005] The first aspect of this application provides a visual optical system, which includes: a first lens having positive optical power, having a convex light-emitting surface and having a reflective polarizing element and a quarter-wave plate attached to its light-incident surface in sequence along the optical axis from the human eye side to the display screen side; and a second lens having positive optical power, having a convex light-incident surface and a convex light-emitting surface.

[0006] Wherein, the light-emitting surface of either the first lens or the second lens is a Fresnel surface; the axial distance TTL from the light-emitting surface of the first lens to the display screen, the center thickness CT1 of the first lens, the center thickness CT2 of the second lens, the radius of curvature R3 of the light-emitting surface of the second lens, and the radius of curvature R4 of the light-incident surface of the second lens satisfy the following condition: 1.5 <TTL / (CT1+CT2)<2.6;-2.0<R4 / R3<0。

[0007] In one or more embodiments, the incident surface of the first lens is spherical or aspherical.

[0008] In one or more embodiments, the light-incident surface of the second lens is aspherical and has a partially reflective element attached to it.

[0009] In one or more embodiments, the combined focal length F1 of the first lens, the reflective polarizing element and the quarter-wave plate and the effective focal length F2 of the second lens satisfy: 0.2 < (F1-F2) / (F1+F2) < 1.2.

[0010] In one or more embodiments, the edge thickness ET1 at the maximum effective diameter of the first lens, the center thickness CTR of the reflective polarizing element, and the center thickness CTQ of the quarter-wave plate satisfy: 12.0 <ET1 / (CTR+CTQ)<20.0。

[0011] In one or more embodiments, the effective focal length F2 of the second lens and the effective focal length F of the visual optics system satisfy: 3.8 <F2 / F<5.7。

[0012] In one or more embodiments, the combined focal length F1 of the first lens, the reflective polarizing element, and the quarter-wave plate satisfies the following relationship with the radius of curvature R1 of the light-emitting surface of the first lens: 0 <F1 / R1<2.2。

[0013] In one or more embodiments, the effective focal length F2 of the second lens, the radius of curvature R3 of the light-exiting surface of the second lens, and the radius of curvature R4 of the light-incident surface of the second lens satisfy: 0 <F2 / (R3-R4)<0.8。

[0014] In one or more embodiments, the refractive index N1 of the first lens, the refractive index N2 of the second lens, the center thickness CT1 of the first lens, and the center thickness CT2 of the second lens satisfy: 2.0 <N1 / N2+CT2 / CT1<4.0。

[0015] In one or more embodiments, the axial distance BFL from the light-incident surface of the second lens to the display screen satisfies: 14.0 mm. <BFL<20.6mm。

[0016] In one or more embodiments, the on-axis distance TTL from the light-emitting surface of the first lens to the display screen and the on-axis distance BFL from the light-incident surface of the second lens to the display screen satisfy: 1.5 <TTL / BFL<2.5。

[0017] In one or more embodiments, the distance SAG22 from the intersection of the edge thickness ET2 at the maximum effective half-aperture of the second lens and the incident surface of the second lens on the optical axis to the maximum effective half-aperture of the incident surface of the second lens on the optical axis satisfies: -4.2 <ET2 / SAG22<-1.5。

[0018] In one or more embodiments, the aperture number FNO of the visual optics system satisfies 7.0 with half of the maximum field of view (Semi-FOV) of the visual optics system. <FNO*TAN(Semi-FOV)<10.2。

[0019] According to a second aspect of this application, a visual optical system is provided, comprising: a first lens having positive optical power, the light-emitting surface of which is convex, and a reflective polarizing element and a quarter-wave plate sequentially attached to the light-incident surface along the optical axis from the human eye side to the display screen side; and a second lens having positive optical power, the light-incident surface of which is convex, and the light-emitting surface of which is convex; wherein the combined focal length F1 of the first lens, the reflective polarizing element and the quarter-wave plate and the effective focal length F2 of the second lens satisfy: 0.2 < (F1-F2) / (F1+F2) < 1.2.

[0020] According to a third aspect of this application, a virtual reality display device is provided, which includes the visual optical system as described in the first or second aspect of this application.

[0021] According to some embodiments of the visual optical system provided in this application, by replacing the aspherical surface with a Fresnel surface, the thickness of the surface is reduced, which can be effectively combined with the plane or curved surface of the rear surface, reducing the increase in thickness caused by the sag, reducing the length of the optical system, and better balancing the length and performance of the folding optical system; by controlling the ratio of the axial distance from the light-emitting surface of the first lens to the display screen to the center thickness of the first lens and the center thickness of the second lens, the overall length of the lens can be controlled to ensure a smaller total length; in addition, by controlling the ratio of the radius of curvature of the light-emitting surface of the second lens to the radius of curvature of the light-incident surface of the second lens, the sensitivity of the spherical surface can be reduced, the lens processing difficulty can be reduced, and the angle of light incidence can be controlled to reduce spherical aberration and increase the system resolution. Attached Figure Description

[0022] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0023] Figure 1 A schematic diagram of the visual optical system according to Embodiment 1 of this application is shown;

[0024] Figure 2A and Figure 2B The on-axis chromatic aberration curve and astigmatism curve of the visual optical system according to Embodiment 1 of this application are shown respectively;

[0025] Figure 3 A schematic diagram of the visual optical system according to Embodiment 2 of this application is shown;

[0026] Figure 4A and Figure 4B The on-axis chromatic aberration curve and astigmatism curve of the visual optical system according to Embodiment 2 of this application are shown respectively;

[0027] Figure 5A schematic diagram of the visual optical system according to Embodiment 3 of this application is shown;

[0028] Figure 6A and Figure 6B The on-axis chromatic aberration curve and astigmatism curve of the visual optical system according to Embodiment 3 of this application are shown respectively;

[0029] Figure 7 A schematic diagram of the visual optical system according to Embodiment 4 of this application is shown;

[0030] Figure 8A and Figure 8B The on-axis chromatic aberration curve and astigmatism curve of the visual optical system according to Embodiment 4 of this application are shown respectively;

[0031] Figure 9 A schematic diagram of the visual optical system according to Embodiment 5 of this application is shown;

[0032] Figure 10A and Figure 10B The on-axis chromatic aberration curve and astigmatism curve of the visual optical system according to Embodiment 5 of this application are shown respectively;

[0033] Figure 11 A schematic diagram of the visual optical system according to Embodiment 6 of this application is shown;

[0034] Figure 12A and Figure 12B The on-axis chromatic aberration curve and astigmatism curve of the visual optical system according to Embodiment 6 of this application are shown respectively;

[0035] Figure 13 A schematic diagram of the visual optical system according to Embodiment 7 of this application is shown;

[0036] Figure 14A and Figure 14B The on-axis chromatic aberration curve and astigmatism curve of the visual optical system according to Embodiment 7 of this application are shown respectively;

[0037] Figure 15 A schematic diagram of the visual optical system according to Embodiment 8 of this application is shown; and

[0038] Figure 16A and Figure 16B The on-axis chromatic aberration curve and astigmatism curve of the visual optical system according to Embodiment 8 of this application are shown respectively. Detailed Implementation

[0039] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this 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.

[0040] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0041] In the accompanying 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 illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0042] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity 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 location of the concaveness 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 subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane is called the image-side surface of the lens.

[0043] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," 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. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0044] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized sense, unless expressly so specified herein.

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other. The following embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. For example, the lens groups (i.e., the first to sixth lenses), lens barrel structures, and spacer elements in the various embodiments of this application can be arbitrarily combined, and it is not limited to the lens group in one embodiment being combined only with the lens barrel structure, spacer elements, etc. of that embodiment.

[0046] The features, principles and other aspects of this application are described in detail below.

[0047] refer to Figure 1 The first aspect of this application provides a visual optical system, which may include a first lens with positive optical power and a second lens with positive optical power arranged sequentially along the optical axis from the human eye side to the display screen side. The first lens and the second lens respectively have an incident light surface near the display screen side and an exit light surface near the human eye side. There may be a gap between the first lens and the second lens.

[0048] In an exemplary embodiment, the light-emitting surface of either the first lens or the second lens is a Fresnel surface. By replacing the aspherical lens with a Fresnel surface, the thickness of this surface is reduced, which can effectively combine it with the plane or curved surface of the subsequent surface, reducing the increase in thickness caused by the sag.

[0049] In an exemplary embodiment, the light-emitting surface of the first lens is convex, and the light-incident surface of the first lens is sequentially attached with a reflective polarizing element and a quarter-wave plate.

[0050] In some implementations, the reflective polarizing element and the quarter-wave plate can be attached separately.

[0051] In other embodiments, the reflective polarizing element and the quarter-wave plate are composite films, avoiding separate attachment and improving attachment efficiency. The composite film, combined with other optical components, allows for multiple light reflections, reducing the height (length) of the optical system. Regarding the application of composite films, while curved surface application increases system variables and can improve external field-of-view performance, the process is more complex, and the quality of the film layer deteriorates after application, compromising system performance. In this application, the composite film is attached to a flat surface or a surface with relatively small curvature, a more mature process than curved surface application, thus reducing the difficulty of film application.

[0052] In an exemplary embodiment, both the light-incident surface and the light-exit surface of the second lens can be convex.

[0053] In an exemplary embodiment, the light incident surface of the first lens can be spherical or aspherical, which can ensure good light deflection when light passes through the first lens.

[0054] In an exemplary embodiment, the light incident surface of the second lens is aspherical and is attached with a partially reflective element to enable light to turn back in the second lens and reduce the height of the optical system.

[0055] According to the visual optical system of the embodiment of the present application, by utilizing the polarization characteristics of light, the image light from the display screen is reflected and refracted multiple times in the second lens and the first lens. By increasing the number of times the image light turns back, the length of the optical system is shortened. At the same time, the number of optical lenses used can also be reduced, achieving the advantages of small size, light weight, and high resolution.

[0056] According to the visual optical system of the embodiment of the present application, an architecture of a planar film plus a Fresnel surface is adopted, optimizing the architecture of the folding optical system, improving the outer field performance, and ensuring that the visual optical system has a small length.

[0057] In an exemplary embodiment, the visual optical system satisfies the following conditional expressions: 1.5 < TTL / (CT1 + CT2) < 2.6; -2.0 < R4 / R3 < 0. Here, TTL is the axial distance from the light exit surface of the first lens to the display screen, CT1 is the central thickness of the first lens, CT2 is the central thickness of the second lens, R3 is the curvature radius of the light exit surface of the second lens, and R4 is the curvature radius of the light incident surface of the second lens. By controlling the ratio of the axial distance from the light exit surface of the first lens to the display screen to the central thicknesses of the first lens and the second lens, the length of the overall lens can be controlled to ensure a small total length. And by controlling the ratio of the curvature radius of the light exit surface of the first lens to the curvature radius of the light incident surface of the second lens, the sensitivity of the spherical surface can be reduced, the processing difficulty of the lens can be decreased, and the incident angle of light can be controlled to reduce spherical aberration and increase the system resolution.

[0058] In an exemplary embodiment, the visual optical system satisfies the following conditional expression: 0.2 < (F1 - F2) / (F1 + F2) < 1.2. Here, F1 is the combined focal length of the first lens, the reflective polarizing element, and the quarter-wave plate, and F2 is the effective focal length of the second lens. By controlling the ratio of the combined focal length of the first lens, the reflective polarizing element, and the quarter-wave plate to the effective focal length of the second lens, the light power distribution of the optical system can be controlled to improve the system performance.

[0059] In an exemplary embodiment, the visual optical system satisfies the following conditional formula: 12.0 < ET1 / (CTR + CTQ) < 20.0. Here, ET1 is the edge thickness at the maximum effective diameter of the first lens, CTR is the central thickness of the reflective polarizing element, and CTQ is the central thickness of the quarter-wave plate. By controlling the ratio of the edge thickness at the maximum effective diameter of the first lens to the central thickness of the reflective polarizing element and the central thickness of the quarter-wave plate, the thickness distribution can be controlled, making the overall thickness distribution more reasonable, thereby reducing the overall thickness of the system.

[0060] In an exemplary embodiment, the visual optical system satisfies the following conditional formula: 3.8 < F2 / F < 5.7. Here, F2 is the effective focal length of the second lens, and F is the effective focal length of the visual optical system. By controlling the ratio of the effective focal length of the second lens to the effective focal length of the visual optical system, the optical power of the second lens can be reasonably controlled, indirectly controlling the focal length of the first lens, which is beneficial to improving the system performance.

[0061] In an exemplary embodiment, the visual optical system satisfies the following conditional formula: 0 < F1 / R1 < 2.2. Here, F1 is the combined focal length of the first lens, the reflective polarizing element, and the quarter-wave plate, and R1 is the curvature radius of the light-emitting surface of the first lens. By controlling the ratio of the combined focal length of the first lens, the reflective polarizing element, and the quarter-wave plate to the curvature radius of the light-emitting surface of the first lens, the combined focal length of this part can be controlled, giving it a reasonable optical power distribution and restricting the shape of the first lens.

[0062] In an exemplary embodiment, the visual optical system satisfies the following conditional formula: 0 < F2 / (R3 - R4) < 0.8. Here, F2 is the effective focal length of the second lens, R3 is the curvature radius of the light-emitting surface of the second lens, and R4 is the curvature radius of the light-incident surface of the second lens. By controlling the ratio of the effective focal length of the second lens to the curvature radius of the light-emitting surface of the second lens and the curvature radius of the light-incident surface of the second lens, the optical power distribution of the system can be effectively controlled, and good light deflection ability and good lens processability of the second lens can be ensured.

[0063] In an exemplary embodiment, the visual optical system satisfies the following conditional formula: 2.0 < N1 / N2 + CT2 / CT1 < 4.0. Here, N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, CT2 is the central thickness of the second lens, and CT1 is the central thickness of the first lens. By controlling the ratio of the refractive index of the first lens to the refractive index of the second lens and the ratio of the central thickness of the second lens to the central thickness of the first lens, the refractive index distribution and thickness distribution of the first and second lenses can be controlled, and then the most suitable refractive index and thickness distribution can be optimized, indirectly helping to control the overall length of the system.

[0064] In an exemplary embodiment, the visual optical system satisfies the following conditional formula: 14.0 mm < BFL < 20.6 mm. Here, BFL is the axial distance from the incident light surface of the second lens to the display screen. By controlling the axial distance from the incident light surface of the second lens to the display screen, it can be ensured that the distance between the display screen and the lens flange surface is not too far, ensuring that the system has a smaller overall length.

[0065] In an exemplary embodiment, the visual optical system satisfies the following conditional formula: 1.5 < TTL / BFL < 2.5. Here, TTL is the axial distance from the emergent light surface of the first lens to the display screen, and BFL is the axial distance from the incident light surface of the second lens to the display screen. By controlling the ratio of the axial distance from the emergent light surface of the first lens to the display screen to the axial distance from the incident light surface of the second lens to the display screen, it can be ensured that there is a smaller axial distance from the emergent light surface of the first lens to the display screen and a smaller axial distance from the incident light surface of the second lens to the display screen, thereby controlling the total length of the system.

[0066] In an exemplary embodiment, the visual optical system satisfies the following conditional formula: -4.2 < ET2 / SAG22 < -1.5. Here, ET2 is the edge thickness at the maximum effective semi-aperture of the second lens, and SAG22 is the distance on the optical axis between the intersection point of the incident light surface of the second lens on the optical axis and the maximum effective semi-aperture of the incident light surface of the second lens. By controlling the ratio of the edge thickness at the maximum effective semi-aperture of the second lens to the distance on the optical axis between the intersection point of the incident light surface of the second lens on the optical axis and the maximum effective semi-aperture of the incident light surface of the second lens, it can be ensured the edge strength of the second lens and good processability. At the same time, the sagittal height of the second lens can be controlled within a reasonable range, making the thickness of the lens more uniform.

[0067] In an exemplary embodiment, the visual optical system satisfies: 7.0 < FNO * TAN(Semi-FOV) < 10.2. Here, FNO is the f-number of the visual optical system, and Semi-FOV is half of the maximum field angle of the visual optical system. By controlling the product of the f-number of the visual optical system and half of the maximum field angle of the visual optical system, it can be ensured that the system has sufficient light input, a larger field angle, and a matching image plane.

[0068] In some embodiments, the visual optical system according to the present application may further include an aperture disposed on the human eye side. The setting of the aperture is beneficial to effectively converge the light entering the optical lens and is beneficial to reducing the aperture of the lens.

[0069] For the visual optical system according to the above embodiments of the present application, two or more lenses can be used. By reasonably distributing the focal lengths, surface shapes, central thicknesses of each lens, and the axial spacings between each lens, etc., the incident light can be effectively converged, the optical total length can be reduced, and the processability can be improved, making the visual optical system more conducive to production and processing.

[0070] In embodiments of this application, at least one of the optical surfaces of the first lens and the second lens is an aspherical mirror surface. An aspherical lens is characterized by a continuously changing curvature from its center to its periphery. Unlike a spherical lens, which has a constant curvature from its center to its periphery, an aspherical lens has superior curvature radius characteristics, offering advantages in improving distortion and astigmatism. By using an aspherical lens, aberrations occurring during imaging can be eliminated as much as possible, thereby improving image quality.

[0071] According to a second aspect of this application, a VR display device is provided, which may include the visual optical system described above.

[0072] In an exemplary embodiment, the VR display device may further include a video perspective lens. A visual optical system with a folding optical structure provides a virtual experience, while the video perspective lens provides a view of the real environment, allowing users to view an image that blends virtual visuals and real-world scenery, thereby enhancing the visual immersion of the VR display device.

[0073] Embodiments 1 to 8 of the visual optical system applicable to the above exemplary embodiments will be further described below with reference to the accompanying drawings and examples.

[0074] Example 1

[0075] Figure 1 A schematic diagram of the visual optical system according to Embodiment 1 of this application is shown. Figure 1 As shown, the visual optical system, along the optical axis from the human eye side to the display screen side, may sequentially include: an aperture stop STO, a first lens E1, a second lens E2, and a display screen. The aperture stop STO may be located on the human eye side. The first lens E1 has a light-emitting surface S1 near the human eye side and a light-incident surface S2 near the display screen side. The second lens E2 has a light-emitting surface S5 near the human eye side and a light-incident surface S6 near the display screen side.

[0076] In this embodiment, the light-emitting surface S5 of the second lens E2 is a thin Fresnel surface. Using a Fresnel surface reduces the thickness of the surface, which can be effectively combined with the plane or curved surface of the subsequent surface, reducing the increase in thickness caused by the sag.

[0077] In this embodiment, the first lens E1 has positive optical power, and the light-emitting surface S1 of the first lens E1 can be a convex surface.

[0078] In this embodiment, the second lens E2 has positive optical power, and both the light-incident surface S6 and the light-outceasing surface S5 of the second lens E2 can be convex.

[0079] In this embodiment, a reflective polarizing element RP and a quarter-wave plate QWP are sequentially attached to the light-incident surface S2 of the first lens E1. The reflective polarizing element RP and the quarter-wave plate QWP have optical surfaces S3 and S4, respectively. When light passes through the reflective polarizing element RP, the reflective polarizing element can reflect light in a certain direction and transmit light orthogonal to the reflected light. The quarter-wave plate QWP can be used to convert between circularly polarized light and linearly polarized light, realizing the folding of the optical path, which is beneficial for shortening the length of the visual optical system.

[0080] In this embodiment, as an exemplary implementation, the light-incident surface S2 of the first lens E1 can be a plane, which facilitates the attachment of the reflective polarizing element RP and the quarter-wave plate QWP.

[0081] As an exemplary implementation, the reflective polarizing element RP and the quarter-wave plate QWP are combined together, avoiding the separate attachment of the reflective polarizing element RP and the quarter-wave plate QWP, thus improving the attachment efficiency.

[0082] As an exemplary embodiment, the incident surface S6 of the second lens E2 can be aspherical. The exit surface S1 of the first lens E1 is aspherical, and the incident surface S2 can be either spherical or aspherical. Aspherical lenses have better radius of curvature characteristics, which has the advantages of improving distortion aberration and astigmatism aberration. By using aspherical lenses, aberrations that occur during imaging can be eliminated as much as possible, thereby improving image quality.

[0083] As an exemplary embodiment, the visual optical system may further include a partially reflective element BS attached to the light-incident surface S6 of the second lens E2. This partially reflective element BS may be, for example, a partially reflective layer. The partially reflective layer has a semi-transmissive and semi-reflective effect on light. By providing a partially reflective layer on the light-incident surface S6 of the second lens E2, and combining it with a reflective polarizing element RP and a quarter-wave plate QWP, light can be reflected multiple times, thereby effectively reducing the overall length of the visual optical system.

[0084] In this embodiment, image light emitted from the display screen is refracted and reflected multiple times by the second lens E2 and the first lens E1 before entering the aperture STO and then the human eye. Specifically, image light from the display screen passes sequentially through the second lens E2 and the quarter-wave plate QWP to reach the reflective polarizing element RP, then is reflected at the reflective polarizing element RP, and passes again through the quarter-wave plate QWP and the second lens E2 to reach the partially reflective element BS. Afterward, the beam is reflected at the partially reflective element BS and sequentially passes through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, and the first lens E1 before entering the aperture STO and exiting towards the human eye. The visual optical system provided in this application effectively shortens the overall length of the visual optical system by folding the required optical path through a combination of light reflection and refraction without affecting image quality.

[0085] Table 1 shows the basic parameters of the visual optical system of Example 1, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm).

[0086]

[0087] Table 1

[0088] In Example 1, the light-emitting surface S1 of the first lens E1, the light-emitting surface S5 of the second lens E2, and the light-incident surface S6 are all aspherical surfaces. The surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0089]

[0090] Where x is the distance vector from the vertex of the aspherical surface at a height of h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (that is, the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface.

[0091] Table 2 lists the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical mirrors S1, S5, and S6 in Example 1. 10 A 12 A 14 A 16 A 18 and A 20 .

[0092] Face number A4 A6 A8 A10 A12 S1 3.27E-06 -3.81E-09 8.09E-12 -7.36E-15 0.00E+00 S5 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S6 7.05E-08 2.12E-10 0.00E+00 0.00E+00 0.00E+00 Face number A14 A16 A18 A20 S1 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S5 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S6 0.00E+00 0.00E+00 0.00E+00 0.00E+00

[0093] Table 2

[0094] Figure 2AThe on-axis chromatic aberration curve of the visual optical system of Embodiment 1 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 2B The astigmatism curves of the visual optical system of Embodiment 1 are shown, representing the meridional image plane curvature and the sagittal image plane curvature. According to... Figures 2A to 2B It can be seen that the visual optical system given in Example 1 can achieve good imaging quality.

[0095] Example 2

[0096] Figure 3 A schematic diagram of the visual optical system according to Embodiment 2 of this application is shown. In Embodiment 2 and the following embodiments, for the sake of brevity, descriptions similar to those in Embodiment 1 will be omitted.

[0097] like Figure 3 As shown, the visual optical system, along the optical axis from the human eye side to the display screen side, may sequentially include: an aperture stop STO, a first lens E1, a second lens E2, and a display screen. The aperture stop STO may be located on the human eye side. The first lens E1 has a light-emitting surface S1 near the human eye side and a light-incident surface S2 near the display screen side. The second lens E2 has a light-emitting surface S5 near the human eye side and a light-incident surface S6 near the display screen side.

[0098] In this embodiment, the light-emitting surface S5 of the second lens E2 is a thin Fresnel surface. Using a Fresnel surface reduces the thickness of the surface, which can be effectively combined with the plane or curved surface of the subsequent surface, reducing the increase in thickness caused by the sag.

[0099] In this embodiment, the first lens E1 has positive optical power, and the light-emitting surface S1 of the first lens E1 can be a convex surface.

[0100] In this embodiment, the second lens E2 has positive optical power, and both the light-incident surface S6 and the light-outceasing surface S5 of the second lens E2 can be convex.

[0101] In this embodiment, a reflective polarizing element RP and a quarter-wave plate QWP are sequentially attached to the light-incident surface S2 of the first lens E1. The reflective polarizing element RP and the quarter-wave plate QWP have optical surfaces S3 and S4, respectively. The light-incident surface S2 of the first lens E1 is planar, which facilitates the attachment of the reflective polarizing element RP and the quarter-wave plate QWP.

[0102] In this embodiment, the light-emitting surface S1 of the first lens E1 is aspherical, and the light-incident surface S6 of the second lens E2 is aspherical. Using aspherical lenses can minimize aberrations that occur during imaging, thereby improving image quality.

[0103] As an exemplary embodiment, the visual optical system may further include a partially reflective element BS attached to the light-incident surface S6 of the second lens E2, the partially reflective element BS being, for example, a partially reflective layer.

[0104] In this embodiment, the image light emitted from the display screen is refracted and reflected multiple times by the second lens E2 and the first lens E1 before entering the aperture STO and then the human eye. Specifically, the image light from the display screen passes sequentially through the second lens E2 and the quarter-wave plate QWP to reach the reflective polarizing element RP, then is reflected at the reflective polarizing element RP, and passes again through the quarter-wave plate QWP and the second lens E2 to reach the partially reflective element BS. After that, the light beam is reflected at the partially reflective element BS and passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, and the first lens E1 before entering the aperture STO and exiting towards the human eye.

[0105] Table 3 shows the basic parameters of the visual optical system of this embodiment 2, where the units for radius of curvature, thickness / distance and focal length are millimeters (mm).

[0106]

[0107] Table 3

[0108] In this embodiment 2, the light-emitting surface S1 of the first lens E1, the light-emitting surface S5 of the second lens E2, and the light-incident surface S6 are all aspherical surfaces. The surface shape of each aspherical lens can be defined by, but is not limited to, the formula (1) given in the above embodiment 1.

[0109] Table 4 lists the higher-order coefficients A4, A6, A8, and A6 that can be used for each aspherical mirror S1, S5, and S6 in Example 2. 10 A 12 A 14 A 16 A 18 and A 20 .

[0110]

[0111]

[0112] Table 4

[0113] Figure 4A The on-axis chromatic aberration curve of the visual optical system of Embodiment 2 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 4B The astigmatism curves of the visual optical system of Embodiment 2 are shown, representing the meridional image plane curvature and the sagittal image plane curvature. According to... Figures 4A to 4BIt can be seen that the visual optical system given in Example 2 can achieve good imaging quality.

[0114] Example 3

[0115] Figure 5 A schematic diagram of the visual optical system according to Embodiment 3 of this application is shown. Figure 5 As shown, the visual optical system, along the optical axis from the human eye side to the display screen side, may sequentially include: an aperture stop STO, a first lens E1, a second lens E2, and a display screen. The aperture stop STO may be located on the human eye side. The first lens E1 has a light-emitting surface S1 near the human eye side and a light-incident surface S2 near the display screen side. The second lens E2 has a light-emitting surface S5 near the human eye side and a light-incident surface S6 near the display screen side.

[0116] In this embodiment, the light-emitting surface S5 of the second lens E2 is a thin Fresnel surface. Using a Fresnel surface reduces the thickness of the surface, which can be effectively combined with the plane or curved surface of the subsequent surface, reducing the increase in thickness caused by the sag.

[0117] In this embodiment, the first lens E1 has positive optical power, and the light-emitting surface S1 of the first lens E1 can be a convex surface.

[0118] In this embodiment, the second lens E2 has positive optical power, and both the light-incident surface S6 and the light-outceasing surface S5 of the second lens E2 can be convex.

[0119] In this embodiment, a reflective polarizing element RP and a quarter-wave plate QWP are sequentially attached to the light-incident surface S2 of the first lens E1. The reflective polarizing element RP and the quarter-wave plate QWP have optical surfaces S3 and S4, respectively. The light-incident surface S2 of the first lens E1 is planar, which facilitates the attachment of the reflective polarizing element RP and the quarter-wave plate QWP.

[0120] In this embodiment, the light-emitting surface S1 of the first lens E1 is aspherical, and the light-incident surface S6 of the second lens E2 is aspherical. Using aspherical lenses can minimize aberrations that occur during imaging, thereby improving image quality.

[0121] As an exemplary embodiment, the visual optical system may further include a partially reflective element BS attached to the light-incident surface S6 of the second lens E2, the partially reflective element BS being, for example, a partially reflective layer.

[0122] In this embodiment, the image light emitted from the display screen is refracted and reflected multiple times by the second lens E2 and the first lens E1 before entering the aperture STO and then the human eye. Specifically, the image light from the display screen passes sequentially through the second lens E2 and the quarter-wave plate QWP to reach the reflective polarizing element RP, then is reflected at the reflective polarizing element RP, and passes again through the quarter-wave plate QWP and the second lens E2 to reach the partially reflective element BS. After that, the light beam is reflected at the partially reflective element BS and passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, and the first lens E1 before entering the aperture STO and exiting towards the human eye.

[0123] Table 5 shows the basic parameters of the visual optical system of this embodiment 3, where the units for radius of curvature, thickness / distance, and focal length are all millimeters (mm).

[0124]

[0125]

[0126] Table 5

[0127] In this embodiment 3, the light-emitting surface S1 of the first lens E1, the light-emitting surface S5 of the second lens E2, and the light-incident surface S6 are all aspherical surfaces. The surface shape of each aspherical lens can be defined by, but is not limited to, the formula (1) given in the above embodiment 1.

[0128] Table 6 lists the higher-order coefficients A4, A6, A8, and A6 that can be used for each aspherical mirror S1, S5, and S6 in Example 3. 10 A 12 A 14 A 16 A 18 and A 20 .

[0129] Face number A4 A6 A8 A10 A12 S1 2.78E-06 -2.84E-09 4.43E-12 -3.81E-15 0.00E+00 S5 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S6 1.55E-07 2.81E-10 0.00E+00 0.00E+00 0.00E+00 Face number A14 A16 A18 A20 S1 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S5 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S6 0.00E+00 0.00E+00 0.00E+00 0.00E+00

[0130] Table 6

[0131] Figure 6A The on-axis chromatic aberration curve of the visual optical system of Embodiment 3 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 6B The astigmatism curves of the visual optical system of Embodiment 3 are shown, representing the meridional image plane curvature and the sagittal image plane curvature. According to... Figures 6A to 6B It can be seen that the visual optical system given in Example 3 can achieve good imaging quality.

[0132] Example 4

[0133] Figure 7A schematic diagram of the visual optical system according to Embodiment 4 of this application is shown. Figure 7 As shown, the visual optical system, along the optical axis from the human eye side to the display screen side, may sequentially include: an aperture stop STO, a first lens E1, a second lens E2, and a display screen. The aperture stop STO may be located on the human eye side. The first lens E1 has a light-emitting surface S1 near the human eye side and a light-incident surface S2 near the display screen side. The second lens E2 has a light-emitting surface S5 near the human eye side and a light-incident surface S6 near the display screen side.

[0134] In this embodiment, the light-emitting surface S5 of the second lens E2 is a thin Fresnel surface. Using a Fresnel surface reduces the thickness of the surface, which can be effectively combined with the plane or curved surface of the subsequent surface, reducing the increase in thickness caused by the sag.

[0135] In this embodiment, the first lens E1 has positive optical power, and the light-emitting surface S1 of the first lens E1 can be a convex surface.

[0136] In this embodiment, the second lens E2 has positive optical power, and both the light-incident surface S6 and the light-outceasing surface S5 of the second lens E2 can be convex.

[0137] In this embodiment, a reflective polarizing element RP and a quarter-wave plate QWP are sequentially attached to the light-incident surface S2 of the first lens E1. The reflective polarizing element RP and the quarter-wave plate QWP have optical surfaces S3 and S4, respectively. The light-incident surface S2 of the first lens E1 is a curved surface with a small curvature, which facilitates the attachment of the reflective polarizing element RP and the quarter-wave plate QWP.

[0138] In this embodiment, the light-emitting surface S1 of the first lens E1 is aspherical, and the light-incident surface S6 of the second lens E2 is aspherical. Using aspherical lenses can minimize aberrations that occur during imaging, thereby improving image quality.

[0139] As an exemplary embodiment, the visual optical system may further include a partially reflective element BS attached to the light-incident surface S6 of the second lens E2, the partially reflective element BS being, for example, a partially reflective layer.

[0140] In this embodiment, the image light emitted from the display screen is refracted and reflected multiple times by the second lens E2 and the first lens E1 before entering the aperture STO and then the human eye. Specifically, the image light from the display screen passes sequentially through the second lens E2 and the quarter-wave plate QWP to reach the reflective polarizing element RP, then is reflected at the reflective polarizing element RP, and passes again through the quarter-wave plate QWP and the second lens E2 to reach the partially reflective element BS. After that, the light beam is reflected at the partially reflective element BS and passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, and the first lens E1 before entering the aperture STO and exiting towards the human eye.

[0141] Table 7 shows the basic parameters of the visual optical system of this embodiment 4, where the units for radius of curvature, thickness / distance, and focal length are all millimeters (mm).

[0142]

[0143] Table 7

[0144] In this embodiment 4, the light-emitting surface S1 of the first lens E1, the light-emitting surface S5 of the second lens E2, and the light-incident surface S6 are all aspherical surfaces. The surface shape of each aspherical lens can be defined by, but is not limited to, the formula (1) given in the above embodiment 1.

[0145] Table 8 lists the higher-order coefficients A4, A6, A8, and A6 that can be used for each aspherical mirror S1, S5, and S6 in Example 4. 10 A 12 A 14 A 16 A 18 and A 20 .

[0146] Face number A4 A6 A8 A10 A12 S1 1.82E-06 3.30E-09 -9.06E-12 6.13E-15 0.00E+00 S5 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S6 3.80E-07 4.16E-10 0.00E+00 0.00E+00 0.00E+00 Face number A14 A16 A18 A20 S1 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S5 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S6 0.00E+00 0.00E+00 0.00E+00 0.00E+00

[0147] Table 8

[0148] Figure 8A The on-axis chromatic aberration curve of the visual optical system of Embodiment 4 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 8B The astigmatism curves of the visual optical system of Embodiment 4 are shown, representing the meridional image plane curvature and the sagittal image plane curvature. According to... Figures 8A to 8B It can be seen that the visual optical system given in Example 4 can achieve good imaging quality.

[0149] Example 5

[0150] Figure 9 A schematic diagram of the visual optical system according to Embodiment 5 of this application is shown. Figure 9 As shown, the visual optical system, along the optical axis from the human eye side to the display screen side, may sequentially include: an aperture stop STO, a first lens E1, a second lens E2, and a display screen. The aperture stop STO may be located on the human eye side. The first lens E1 has a light-emitting surface S1 near the human eye side and a light-incident surface S2 near the display screen side. The second lens E2 has a light-emitting surface S5 near the human eye side and a light-incident surface S6 near the display screen side.

[0151] In this embodiment, the light-emitting surface S1 of the first lens E1 is a thin Fresnel surface. Using a Fresnel surface reduces the thickness of the surface, thus reducing the increase in thickness caused by the sag.

[0152] In this embodiment, the first lens E1 has positive optical power, and the light-emitting surface S1 of the first lens E1 can be a convex surface.

[0153] In this embodiment, the second lens E2 has positive optical power, and both the light-incident surface S6 and the light-outceasing surface S5 of the second lens E2 can be convex.

[0154] In this embodiment, a reflective polarizing element RP and a quarter-wave plate QWP are sequentially attached to the light-incident surface S2 of the first lens E1. The reflective polarizing element RP and the quarter-wave plate QWP have optical surfaces S3 and S4, respectively. The light-incident surface S2 of the first lens E1 is planar, which facilitates the attachment of the reflective polarizing element RP and the quarter-wave plate QWP.

[0155] In this embodiment, the light-emitting surface S1 of the first lens E1 is aspherical, and the light-incident surface S6 of the second lens E2 is aspherical. Using aspherical lenses can minimize aberrations that occur during imaging, thereby improving image quality.

[0156] As an exemplary embodiment, the visual optical system may further include a partially reflective element BS attached to the light-incident surface S6 of the second lens E2, the partially reflective element BS being, for example, a partially reflective layer.

[0157] In this embodiment, the image light emitted from the display screen is refracted and reflected multiple times by the second lens E2 and the first lens E1 before entering the aperture STO and then the human eye. Specifically, the image light from the display screen passes sequentially through the second lens E2 and the quarter-wave plate QWP to reach the reflective polarizing element RP, then is reflected at the reflective polarizing element RP, and passes again through the quarter-wave plate QWP and the second lens E2 to reach the partially reflective element BS. After that, the light beam is reflected at the partially reflective element BS and passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, and the first lens E1 before entering the aperture STO and exiting towards the human eye.

[0158] Table 9 shows the basic parameters of the visual optical system of this embodiment 5, where the units for radius of curvature, thickness / distance, and focal length are all millimeters (mm).

[0159]

[0160] Table 9

[0161] In this embodiment 5, the light-emitting surface S1 of the first lens E1 and the light-incident surface S6 of the second lens E2 are aspherical surfaces. The surface shape of each aspherical lens can be limited by, but is not limited to, the formula (1) given in the above embodiment 1.

[0162] Table 10 lists the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical mirrors S1 and S6 in Example 5. 10 A 12 A 14 A 16 A 18 and A 20 .

[0163] Face number A4 A6 A8 A10 A12 S1 1.82E-06 3.30E-09 -9.06E-12 6.13E-15 0.00E+00 S6 3.80E-07 4.16E-10 0.00E+00 0.00E+00 0.00E+00 Face number A14 A16 A18 A20 S1 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S6 0.00E+00 0.00E+00 0.00E+00 0.00E+00

[0164] Table 10

[0165] Figure 10A The on-axis chromatic aberration curve of the visual optical system of Embodiment 5 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 10B The astigmatism curves of the visual optical system of Embodiment 5 are shown, representing the meridional image plane curvature and the sagittal image plane curvature. According to... Figures 10A to 10B It can be seen that the visual optical system given in Example 5 can achieve good imaging quality.

[0166] Example 6

[0167] Figure 11 A schematic diagram of the visual optical system according to Embodiment 6 of this application is shown. Figure 11 As shown, the visual optical system, along the optical axis from the human eye side to the display screen side, may sequentially include: an aperture stop STO, a first lens E1, a second lens E2, and a display screen. The aperture stop STO may be located on the human eye side. The first lens E1 has a light-emitting surface S1 near the human eye side and a light-incident surface S2 near the display screen side. The second lens E2 has a light-emitting surface S5 near the human eye side and a light-incident surface S6 near the display screen side.

[0168] In this embodiment, the light-emitting surface S1 of the first lens E1 is a thin Fresnel surface. Using a Fresnel surface reduces the thickness of the surface, thus reducing the increase in thickness caused by the sag.

[0169] In this embodiment, the first lens E1 has positive optical power, and the light-emitting surface S1 of the first lens E1 can be a convex surface.

[0170] In this embodiment, the second lens E2 has positive optical power, and both the light-incident surface S6 and the light-outceasing surface S5 of the second lens E2 can be convex.

[0171] In this embodiment, a reflective polarizing element RP and a quarter-wave plate QWP are sequentially attached to the light-incident surface S2 of the first lens E1. The reflective polarizing element RP and the quarter-wave plate QWP have optical surfaces S3 and S4, respectively. The light-incident surface S2 of the first lens E1 is a curved surface with a small curvature, which facilitates the attachment of the reflective polarizing element RP and the quarter-wave plate QWP.

[0172] In this embodiment, the light-emitting surface S1 and the light-incident surface S2 of the first lens E1 are both aspherical, and the light-incident surface S6 of the second lens E2 is aspherical. Using aspherical lenses can minimize aberrations that occur during imaging, thereby improving image quality.

[0173] As an exemplary embodiment, the visual optical system may further include a partially reflective element BS attached to the light-incident surface S6 of the second lens E2, the partially reflective element BS being, for example, a partially reflective layer.

[0174] In this embodiment, the image light emitted from the display screen is refracted and reflected multiple times by the second lens E2 and the first lens E1 before entering the aperture STO and then the human eye. Specifically, the image light from the display screen passes sequentially through the second lens E2 and the quarter-wave plate QWP to reach the reflective polarizing element RP, then is reflected at the reflective polarizing element RP, and passes again through the quarter-wave plate QWP and the second lens E2 to reach the partially reflective element BS. After that, the light beam is reflected at the partially reflective element BS and passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, and the first lens E1 before entering the aperture STO and exiting towards the human eye.

[0175] Table 11 shows the basic parameters of the visual optical system of Embodiment 6, where the units for radius of curvature, thickness / distance, and focal length are all millimeters (mm).

[0176]

[0177]

[0178] Table 11

[0179] In this embodiment 6, the light-emitting surface S1 and light-incident surface S2 of the first lens E1, the optical surface S3 of the reflective polarizing element RP, the optical surface S4 of the quarter-wave plate QWP, and the light-incident surface S6 of the second lens E2 are aspherical. The surface shape of each aspherical lens can be defined by, but is not limited to, the formula (1) given in the above embodiment 1.

[0180] Table 12 lists the higher-order coefficients A4, A6, A8, and A6 that can be used for each aspherical mirror S1, S2, S3, S4, and S6 in Example 6. 10 A 12 A 14 A 16 A 18 and A 20 .

[0181] Face number A4 A6 A8 A10 A12 S1 5.31E-06 -8.82E-10 0.00E+00 0.00E+00 0.00E+00 S2 5.90E-07 6.10E-10 -1.15E-13 0.00E+00 0.00E+00 S3 7.14E-07 5.89E-10 -9.39E-14 0.00E+00 0.00E+00 S4 4.76E-07 7.07E-10 -1.02E-13 0.00E+00 0.00E+00 S6 5.08E-07 4.24E-10 0.00E+00 0.00E+00 0.00E+00 Face number A14 A16 A18 A20 S1 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S2 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S3 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S4 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S6 0.00E+00 0.00E+00 0.00E+00 0.00E+00

[0182] Table 12

[0183] Figure 12A The on-axis chromatic aberration curve of the visual optical system of Embodiment 6 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 12B The astigmatism curves of the visual optical system of Embodiment 6 are shown, representing the meridional image plane curvature and the sagittal image plane curvature. According to... Figures 12A to 12B It can be seen that the visual optical system given in Example 6 can achieve good imaging quality.

[0184] Example 7

[0185] Figure 13 A schematic diagram of the visual optical system according to Embodiment 7 of this application is shown. Figure 13 As shown, the visual optical system, along the optical axis from the human eye side to the display screen side, may sequentially include: an aperture stop STO, a first lens E1, a second lens E2, and a display screen. The aperture stop STO may be located on the human eye side. The first lens E1 has a light-emitting surface S1 near the human eye side and a light-incident surface S2 near the display screen side. The second lens E2 has a light-emitting surface S5 near the human eye side and a light-incident surface S6 near the display screen side.

[0186] In this embodiment, the light-emitting surface S1 of the first lens E1 is a thin Fresnel surface. Using a Fresnel surface reduces the thickness of the surface, thus reducing the increase in thickness caused by the sag.

[0187] In this embodiment, the first lens E1 has positive optical power, and the light-emitting surface S1 of the first lens E1 can be a convex surface.

[0188] In this embodiment, the second lens E2 has positive optical power, and both the light-incident surface S6 and the light-outceasing surface S5 of the second lens E2 can be convex.

[0189] In this embodiment, a reflective polarizing element RP and a quarter-wave plate QWP are sequentially attached to the light-incident surface S2 of the first lens E1. The reflective polarizing element RP and the quarter-wave plate QWP have optical surfaces S3 and S4, respectively. The light-incident surface S2 of the first lens E1 is a curved surface with a small curvature, which facilitates the attachment of the reflective polarizing element RP and the quarter-wave plate QWP.

[0190] In this embodiment, the light-emitting surface S1 and the light-incident surface S2 of the first lens E1 are both aspherical, and the light-incident surface S6 of the second lens E2 is aspherical. Using aspherical lenses can minimize aberrations that occur during imaging, thereby improving image quality.

[0191] As an exemplary embodiment, the visual optical system may further include a partially reflective element BS attached to the light-incident surface S6 of the second lens E2, the partially reflective element BS being, for example, a partially reflective layer.

[0192] In this embodiment, the image light emitted from the display screen is refracted and reflected multiple times by the second lens E2 and the first lens E1 before entering the aperture STO and then the human eye. Specifically, the image light from the display screen passes sequentially through the second lens E2 and the quarter-wave plate QWP to reach the reflective polarizing element RP, then is reflected at the reflective polarizing element RP, and passes again through the quarter-wave plate QWP and the second lens E2 to reach the partially reflective element BS. After that, the light beam is reflected at the partially reflective element BS and passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, and the first lens E1 before entering the aperture STO and exiting towards the human eye.

[0193] Table 13 shows the basic parameters of the visual optical system of Embodiment 7, where the units for radius of curvature, thickness / distance, and focal length are all millimeters (mm).

[0194]

[0195]

[0196] Table 13

[0197] In this embodiment 7, the light-emitting surface S1 and light-incident surface S2 of the first lens E1, the optical surface S3 of the reflective polarizing element RP, the optical surface S4 of the quarter-wave plate QWP, and the light-incident surface S6 of the second lens E2 are aspherical. The surface shape of each aspherical lens can be defined by, but is not limited to, the formula (1) given in the above embodiment 1.

[0198] Table 14 lists the higher-order coefficients A4, A6, A8, and A6 that can be used for each aspherical mirror S1, S2, S3, S4, and S6 in Example 7. 10 A 12 A 14 A 16 A 18 and A 20 .

[0199] Face number A4 A6 A8 A10 A12 S1 6.33E-06 -1.30E-09 0.00E+00 0.00E+00 0.00E+00 S2 6.51E-07 7.18E-10 -1.61E-13 0.00E+00 0.00E+00 S3 6.92E-07 7.22E-10 -1.51E-13 0.00E+00 0.00E+00 S4 6.50E-07 7.51E-10 -1.58E-13 0.00E+00 0.00E+00 S6 6.80E-07 4.67E-10 0.00E+00 0.00E+00 0.00E+00 Face number A14 A16 A18 A20 S1 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S2 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S3 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S4 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S6 0.00E+00 0.00E+00 0.00E+00 0.00E+00

[0200] Table 14

[0201] Figure 14A The on-axis chromatic aberration curve of the visual optical system of Embodiment 7 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 14B The astigmatism curves of the visual optical system of Embodiment 7 are shown, representing the meridional image plane curvature and the sagittal image plane curvature. According to... Figures 14A to 14B As can be seen, the visual optical system given in Example 7 can achieve good imaging quality.

[0202] Example 8

[0203] Figure 15 A schematic diagram of the visual optical system according to Embodiment 8 of this application is shown. Figure 15 As shown, the visual optical system, along the optical axis from the human eye side to the display screen side, may sequentially include: an aperture stop STO, a first lens E1, a second lens E2, and a display screen. The aperture stop STO may be located on the human eye side. The first lens E1 has a light-emitting surface S1 near the human eye side and a light-incident surface S2 near the display screen side. The second lens E2 has a light-emitting surface S5 near the human eye side and a light-incident surface S6 near the display screen side.

[0204] In this embodiment, the light-emitting surface S1 of the first lens E1 is a thin Fresnel surface. Using a Fresnel surface reduces the thickness of the surface, thus reducing the increase in thickness caused by the sag.

[0205] In this embodiment, the first lens E1 has positive optical power, and the light-emitting surface S1 of the first lens E1 can be a convex surface.

[0206] In this embodiment, the second lens E2 has positive optical power, and both the light-incident surface S6 and the light-outceasing surface S5 of the second lens E2 can be convex.

[0207] In this embodiment, a reflective polarizing element RP and a quarter-wave plate QWP are sequentially attached to the light-incident surface S2 of the first lens E1, and the reflective polarizing element RP and the quarter-wave plate QWP have optical surfaces S3 and S4, respectively.

[0208] In this embodiment, the light-emitting surface S1 of the first lens E1 is aspherical, and the light-incident surface S6 of the second lens E2 is aspherical. Using aspherical lenses can minimize aberrations that occur during imaging, thereby improving image quality.

[0209] As an exemplary embodiment, the visual optical system may further include a partially reflective element BS attached to the light-incident surface S6 of the second lens E2, the partially reflective element BS being, for example, a partially reflective layer.

[0210] In this embodiment, the image light emitted from the display screen is refracted and reflected multiple times by the second lens E2 and the first lens E1 before entering the aperture STO and then the human eye. Specifically, the image light from the display screen passes sequentially through the second lens E2 and the quarter-wave plate QWP to reach the reflective polarizing element RP, then is reflected at the reflective polarizing element RP, and passes again through the quarter-wave plate QWP and the second lens E2 to reach the partially reflective element BS. After that, the light beam is reflected at the partially reflective element BS and passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, and the first lens E1 before entering the aperture STO and exiting towards the human eye.

[0211] Table 15 shows the basic parameters of the visual optical system of Embodiment 8, where the units for radius of curvature, thickness / distance, and focal length are all millimeters (mm).

[0212]

[0213] Table 15

[0214] In this embodiment 8, the light-emitting surface S1 of the first lens E1 and the light-incident surface S6 of the second lens E2 are aspherical surfaces. The surface shape of each aspherical lens can be limited by, but is not limited to, the formula (1) given in the above embodiment 1.

[0215] Table 16 lists the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical mirrors S1 and S6 in Example 8. 10 A 12 A 14 A 16 A 18 and A 20 .

[0216]

[0217]

[0218] Table 16

[0219] Figure 16A The on-axis chromatic aberration curve of the visual optical system of Embodiment 8 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 16B The astigmatism curves of the visual optical system of Embodiment 8 are shown, representing the meridional image plane curvature and the sagittal image plane curvature. According to... Figures 16A to 16B It can be seen that the visual optical system given in Example 8 can achieve good imaging quality.

[0220] Table 17 below shows the optical parameters of the visual optical systems of Embodiments 1 to 8, such as the on-axis distance TTL from the light-emitting surface of the first lens to the display screen, the image height ImgH, half of the maximum field of view (Semi-FOV), the effective focal length of the visual optical system, and the focal length values ​​of each lens. The units for distance, image height, and focal length are all millimeters (mm).

[0221] Parameters / Examples 1 2 3 4 5 6 7 8 TTL 36.46 33.15 35.77 33.44 35.31 33.73 35.61 32.10 ImgH 26.40 22.10 26.59 26.06 25.78 24.61 26.40 25.48 Semi-FOV (°) 47.97 47.97 50.00 47.97 47.97 47.97 50.00 47.97 F 34.66 29.55 33.96 33.83 33.62 32.97 33.56 32.47 F1 90894.76 68765.42 123101.61 1256.26 115638.30 3535.17 4378.59 510.17 F2 143.75 121.05 140.00 140.08 159.72 147.13 152.43 179.61

[0222] Table 17 summarizes that in Examples 1 to 8, the visual optical systems respectively satisfy the conditions shown in Table 18 below.

[0223] Conditional / Example 1 2 3 4 5 6 7 8 TTL / (CT1+CT2) 2.46 2.37 2.42 2.04 2.39 1.85 2.17 2.17 R4 / R3 -1.62 -1.73 -1.64 -1.02 -0.87 -0.93 -0.95 -0.07 (F1-F2) / (F1+F2) 1.00 1.00 1.00 0.80 1.00 0.92 0.93 0.48 ET1 / (CTR+CTQ) 14.87 19.71 14.82 12.26 16.00 18.11 18.88 13.16 F2 / F 4.15 4.10 4.12 4.14 4.75 4.46 4.54 5.53 F1 / R1 2.03 2.03 2.03 0.04 2.03 0.22 0.25 0.02 F2 / (R3-R4) 0.48 0.47 0.48 0.51 0.51 0.51 0.51 0.13 N1 / N2+CT2 / CT1 3.08 2.33 3.08 3.81 3.08 3.41 2.99 3.08 BFL 20.46 17.95 19.77 15.86 19.31 14.34 18.02 16.10 TTL / BFL 1.78 1.85 1.81 2.11 1.83 2.35 1.98 1.99 ET2 / SAG22 -3.85 -2.64 -3.37 -3.46 -2.00 -3.35 -2.79 -1.79 FNO*TAN(Semi-FOV) 9.61 8.20 10.12 9.38 9.33 7.32 10.00 9.01

[0224] Table 18

[0225] Example 9

[0226] This embodiment 9 provides a virtual reality (VR) display device, which may include the visual optical system of any of the foregoing embodiments, and may also include a video perspective lens.

[0227] The VR display device in this embodiment uses a dual- or multi-lens visual optical system. By sequentially attaching reflective polarizing elements and quarter-wave plates to a flat surface or a curved surface with small curvature, and combining them with a thin Fresnel surface, the total length and overall volume of the optical system are reduced. While improving the external field of view performance, good imaging quality is ensured, which greatly enhances the visual immersion of the VR display device.

[0228] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A visual optical system, characterized in that Comprise, from the human eye side to the display screen side along the optical axis in order: A first lens with positive focal power, the light-outcoming surface of which is a convex surface, and the light-coming surface of which is sequentially attached with a reflective polarizing element and a quarter-wave plate; and A second lens with positive focal power, the light-coming surface of which is a convex surface, and the light-outcoming surface of which is a convex surface; Wherein, the number of lenses with focal power in the visual optical system is two; The light-outcoming surface of the first lens or the light-outcoming surface of the second lens is a Fresnel surface; The on-axis distance TTL from the light-outcoming surface of the first lens to the display screen, the central thickness CT1 of the first lens, the central thickness CT2 of the second lens, the curvature radius R3 of the light-outcoming surface of the second lens, and the curvature radius R4 of the light-coming surface of the second lens satisfy the following conditional expression: 1.85≤TTL / (CT1+CT2)≤2.46; -1.73≤R4 / R3≤-0.

07.

2. The visual optical system of claim 1, wherein, The light-coming surface of the first lens is a spherical surface or an aspherical surface.

3. The visual optical system of claim 1, wherein, The light-coming surface of the second lens is an aspherical surface and is attached with a partial reflective element.

4. The visual optical system of claim 1, wherein, The combined focal length F1 of the first lens, the reflective polarizing element and the quarter-wave plate, and the effective focal length F2 of the second lens satisfy: 0.48≤(F1-F2) / (F1+F2)≤1.

5. The visual optical system of claim 1, wherein, The edge thickness ET1 of the first lens at the maximum effective diameter, the central thickness CTR of the reflective polarizing element, and the central thickness CTQ of the quarter-wave plate satisfy: 12.26≤ET1 / (CTR+CTQ)≤19.

71.

6. The visual optical system of claim 1, wherein, The effective focal length F2 of the second lens and the effective focal length F of the visual optical system satisfy: 4.10≤F2 / F≤5.

53.

7. The visual optical system of claim 1, wherein, The combined focal length F1 of the first lens, the reflective polarizing element and the quarter-wave plate, and the curvature radius R1 of the light-outcoming surface of the first lens satisfy: 0<F1 / R1≤2.

03.

8. The visual optical system of claim 1, wherein, The effective focal length F2 of the second lens, the curvature radius R3 of the light-outcoming surface of the second lens, and the curvature radius R4 of the light-coming surface of the second lens satisfy: 0.13≤F2 / (R3-R4)≤0.

51.

9. The visual optical system of claim 1, wherein, The refractive index N1 of the first lens, the refractive index N2 of the second lens, the central thickness CT1 of the first lens, and the central thickness CT2 of the second lens satisfy: 2.33≤N1 / N2+CT2 / CT1≤3.

81.

10. The visual optics system of any one of claims 1-9, wherein, The on-axis distance BFL from the light-coming surface of the second lens to the display screen satisfies: 14.34mm≤BFL≤20.46mm.

11. The visual optics system of any one of claims 1-9, wherein, The on-axis distance TTL from the light-outcoming surface of the first lens to the display screen and the on-axis distance BFL from the light-coming surface of the second lens to the display screen satisfy: 1.78≤TTL / BFL≤2.

35.

12. The visual optical system according to any one of claims 1-9, wherein, The edge thickness ET2 of the second lens at the maximum effective half-diameter and the distance SAG22 from the intersection of the light-coming surface of the second lens on the optical axis to the maximum effective half-diameter of the light-coming surface of the second lens on the optical axis satisfy: -3.85≤ET2 / SAG22≤-1.

79.

13. The visual optical system according to any of claims 1-9, wherein, The F-number FNO of the visual optical system and the half of the maximum field of view angle Semi-FOV of the visual optical system satisfy: 7.32≤FNO TAN(Semi-FOV)≤10.

12.

14. A virtual reality display device, comprising: The visual optical system as claimed in any one of claims 1-13.

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