Visual system

Abstract

The present disclosure provides a visual system, which includes, in sequence from the first side to the second side along the optical axis, a first lens with positive optical power, a reflective polarizing element, a quarter wave plate, a second lens with positive optical power, a partially reflecting element and a third lens with positive optical power; wherein the position of the first lens on the optical axis relative to the image plane on the second side is fixed, and the distance of the second lens on the optical axis relative to the first lens is adjustable; the visual system satisfies: 1.15≤fg / f2≤1.50, 1.55<ΔL / Δf<2.1, fg is the combined focal length of the first lens, the reflective polarizing element and the quarter wave plate, f2 is the effective focal length of the second lens, ΔL is the movable distance of the second lens when the visual system switches between the first state and the second state, and Δf is the difference between the total effective focal length when the visual system is in the first state and the total effective focal length when the visual system is in the second state.

Description

Technical Field

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

[0002] With the development of science and technology, virtual reality devices and / or augmented reality devices are widely used in fields such as gaming, education, medical treatment, and engineering. The visual systems of virtual reality devices and / or augmented reality devices usually adopt Fresnel lenses. The overall length of such visual systems using Fresnel lenses is relatively large, and the volume and weight are relatively large, which affects the user experience. Moreover, such visual systems using Fresnel lenses do not have the function of diopter adjustment and cannot meet the usage requirements of users with different diopters. Summary of the Invention

[0003] On the one hand, the present disclosure provides such a visual system, which sequentially includes a first lens with a positive optical power, a reflective polarizing element, a quarter-wave plate, a second lens with a positive optical power, a partially reflective element, and a third lens with a positive optical power along the optical axis from the first side to the second side. The first side of the first lens is convex, and the second side is flat. The second side of the second lens is convex. The second side of the third lens is convex. Among them, the position of the first lens on the optical axis relative to the image plane on the second side is fixed, and the distance of the second lens on the optical axis relative to the first lens is adjustable. The number of lenses with optical power in the visual system is three. The visual system satisfies: 1.15 ≤ fg / f2 ≤ 1.50, 1.55 < ΔL / Δf < 2.1, where fg is the combined focal length of the first lens, the reflective polarizing element, and the quarter-wave plate, f2 is the effective focal length of the second lens, ΔL is the movable distance of the second lens when the visual system switches between the first state and the second state, and Δf is the difference between the total effective focal length of the visual system in the first state and the total effective focal length of the visual system in the second state.

[0004] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 6.65 < TD / ΔL < 7.8, where TD is the axial distance from the first side of the first lens to the second side of the third lens, and ΔL is the movable distance of the second lens when the visual system switches between the first state and the second state.

[0005] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 8.64 mm ≤ L13 ≤ 9.43 mm, where L13 is the axial distance from the second side of the first lens to the first side of the third lens.

[0006] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 5.15 < EPD / Δf < 6.8, where EPD is the entrance pupil diameter of the visual system, and Δf is the difference between the total effective focal length of the visual system in the first state and the total effective focal length of the visual system in the second state.

[0007] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 2.15 mm < ΔL < 2.45 mm, where ΔL is the movable distance of the second lens when the visual system switches between the first state and the second state.

[0008] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 3.0 ≤ fm / CT2 ≤ 3.33, where fm is the total effective focal length of the visual system in the first state, and CT2 is the central thickness of the second lens on the optical axis.

[0009] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 5.1 < (CT1 + CTR + CTQ) / T12n < 6.4, where CT1 is the central thickness of the first lens on the optical axis, CTR is the central thickness of the reflective polarizing element on the optical axis, CTQ is the central thickness of the quarter-wave plate on the optical axis, and T12n is the on-axis distance from the second side of the first lens to the first side of the second lens when the visual system is in the second state.

[0010] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 1.07 ≤ CT3 / T23n ≤ 1.41, where CT3 is the central thickness of the third lens on the optical axis, and T23n is the on-axis distance from the second side of the second lens to the first side of the third lens when the visual system is in the second state.

[0011] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 7.36 ≤ f1 / fn ≤ 10.40, where f1 is the effective focal length of the first lens, and fn is the total effective focal length of the visual system in the second state.

[0012] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: -2.6 < f3 / R6 < -1.8, where f3 is the effective focal length of the third lens, and R6 is the radius of curvature of the second side of the third lens.

[0013] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 5.35 < fm / T12m < 5.75, where fm is the total effective focal length of the visual system in the first state, and T12m is the on-axis distance from the second side of the first lens to the first side of the second lens when the visual system is in the first state.

[0014] According to an exemplary embodiment of the present disclosure, the visual system also satisfies: -18.65≤R4 / (T23m+T23n)≤-12.83, wherein R4 is the radius of curvature of the second side surface of the second lens, T23m is the on-axis distance from the second side surface of the second lens to the first side surface of the third lens when the visual system is in the first state, and T23n is the on-axis distance from the second side surface of the second lens to the first side surface of the third lens when the visual system is in the second state.

[0015] According to an exemplary embodiment of the present disclosure, the visual system also satisfies: 3.09≤f2 / (fm+fn)≤3.30, wherein f2 is the effective focal length of the second lens, fm is the total effective focal length when the visual system is in the first state, and fn is the total effective focal length when the visual system is in the second state.

[0016] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: -11.52≤R4 / CT2≤-10.39, wherein R4 is the radius of curvature of the second side surface of the second lens, and CT2 is the center thickness of the second lens on the optical axis.

[0017] The visual system provided by the present disclosure can realize the refraction of the light path by using a reflective polarizing element, a quarter wave plate and a partial reflective element, and the diopter adjustment of the visual system can be realized by moving the second lens. At the same time, by constraining fg / f2 and ΔL / Δf within a reasonable range, the visual system can be switched between the first state and the second state, and the visual system has a good MTF (Modulation Transfer Function) value in different states, so that users with different diopters can see clear images. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features, objects and advantages of the present disclosure will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings, in which:

[0019] Figure 1 A schematic diagram showing the structure of a visual system in a first state according to Embodiment 1 of the present disclosure;

[0020] Figure 2 shows a modulation transfer function curve when the visual system according to Embodiment 1 of the present disclosure is in a first state;

[0021] Figure 3 A schematic diagram showing the structure of the visual system according to Embodiment 1 of the present disclosure when it is in the second state;

[0022] Figure 4 shows a modulation transfer function curve when the visual system according to embodiment 1 of the present disclosure is in the second state;

[0023] Figure 5 A schematic diagram showing the structure of a visual system in a first state according to Embodiment 2 of the present disclosure;

[0024] Figure 6 shows a modulation transfer function curve when the visual system according to Embodiment 2 of the present disclosure is in a first state;

[0025] Figure 7 A schematic diagram showing the structure of the visual system according to Embodiment 2 of the present disclosure when it is in the second state;

[0026] Figure 8 shows a modulation transfer function curve when the visual system according to Embodiment 2 of the present disclosure is in the second state;

[0027] Fig. 9 A schematic diagram showing the structure of a visual system in a first state according to Embodiment 3 of the present disclosure;

[0028] Fig.10 shows a modulation transfer function curve when the visual system according to Embodiment 3 of the present disclosure is in a first state;

[0029] Fig.11 A schematic diagram showing the structure of a visual system in a second state according to Embodiment 3 of the present disclosure;

[0030] Fig.12 shows a modulation transfer function curve when the visual system according to Embodiment 3 of the present disclosure is in the second state;

[0031] Fig.13 A schematic diagram showing the structure of a visual system in a first state according to Embodiment 4 of the present disclosure;

[0032] Fig.14 shows a modulation transfer function curve when the visual system according to Embodiment 4 of the present disclosure is in a first state;

[0033] Fig.15 A schematic diagram showing the structure of a visual system in a second state according to Embodiment 4 of the present disclosure;

[0034] Fig.16 A modulation transfer function curve is shown when the visual system according to Example 4 of the present disclosure is in the second state. DETAILED DESCRIPTION

[0035] In order to better understand the present disclosure, a more detailed description will be made of various aspects of the present disclosure with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present disclosure, and do not limit the scope of the present disclosure in any way. Throughout the specification, the same figure numerals refer to the same elements.

[0036] It should be noted that in this specification, the expressions of first, second, 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 disclosure, the first lens discussed below may also be referred to as the second lens.

[0037] 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.

[0038] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the 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.

[0039] 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 embodiments of the present disclosure, the term "may" is used to mean "one or more embodiments of the present disclosure". And, the term "exemplary" is intended to refer to an example or illustration.

[0040] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with 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 document.

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present disclosure may be combined with each other. The present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] The features, principles and other aspects of the present disclosure are described in detail below.

[0043] The first aspect of the present disclosure provides such a visual system, which may include a first lens, a reflective polarizing element, a quarter wave plate, a second lens, a partial reflective element, and a third lens arranged in sequence from the first side to the second side along the optical axis. The number of lenses with optical power in the visual system may be three. The reflective polarizing element, the quarter wave plate, and the partial reflective element can be used to refract the light path, effectively shorten the body length of the visual system, reduce the volume and weight of the visual system, and realize the lightness of the visual system.

[0044] In an exemplary embodiment, the first lens may have positive optical power. The first side surface of the first lens may be a convex surface, and the second side surface may be a flat surface.

[0045] In an exemplary embodiment, the second lens may have positive optical power. The first side surface of the second lens may be a convex surface or a concave surface, and the second side surface may be a convex surface.

[0046] In an exemplary embodiment, the third lens may have positive optical power. The first side surface of the third lens may be a concave surface or a flat surface, and the second side surface may be a convex surface.

[0047] In an exemplary embodiment, the reflective polarizing element and the quarter wave plate may be attached to each other and to the second side surface of the first lens. For example, the reflective polarizing element is at least partially attached to the second side surface of the first lens, and the quarter wave plate is at least partially attached to the second side surface of the reflective polarizing element. The quarter wave plate can be used to change the polarization state of light, for example, converting circularly polarized light into linearly polarized light, or converting linearly polarized light into circularly polarized light. The reflective polarizing element can reflect light in a predetermined direction (e.g., linearly polarized light) and transmit light in a direction orthogonal to the predetermined direction (e.g., linearly polarized light).

[0048] In an exemplary embodiment, the partially reflective element may be located on the second side surface of the second lens and at least partially adhered to the second side surface of the second lens. The partially reflective element may have a semi-transmissive and semi-reflective effect on the light. By arranging the partially reflective element on the second side surface of the second lens and combining the reflective polarizing element and the quarter wave plate, the light can be refracted multiple times, effectively reducing the main body length of the visual system.

[0049] In an exemplary embodiment, the visual system may further include an aperture, which may be disposed between the first side and the first lens. Image light from the second side is transmitted to the aperture after multiple refractions and reflections through the third lens, the partially reflective element, the second lens, the quarter wave plate, the reflective polarizing element, the first lens, etc., and finally forms a virtual image at a predetermined position. As an example, the aperture may be, for example, the pupil of the user.

[0050] In an exemplary embodiment, an image surface may be provided on the second side of the visual system. A display screen may be provided on the image surface. The image light from the display screen may sequentially pass through the third lens, the second lens, and the quarter wave plate to reach the reflective polarizing element, and then be reflected at the reflective polarizing element to form a first reflected image light. The first reflected image light passes through the quarter wave plate, the second lens, and reaches the partially reflective element on the second side of the second lens, and then is reflected at the partially reflective element to form a second reflected image light. The second reflected image light sequentially passes through the second lens, the quarter wave plate, the reflective polarizing element, the first lens to the aperture (such as the user's pupil) and is finally imaged at a predetermined position. The visual system provided by the present disclosure folds the required optical path without affecting the projection quality by combining light reflection and refraction, thereby effectively shortening the main body length of the visual system.

[0051] In an exemplary embodiment, the positions of the first lens and the third lens on the optical axis relative to the image plane are fixed. The second lens can be moved relative to the first lens along the optical axis, that is, the distance of the second lens relative to the first lens on the optical axis is adjustable. By moving the second lens, the visual system can be switched between the first state and the second state, and the diopter adjustment of the visual system can be achieved, thereby meeting the usage needs of users with different diopters, for example, meeting the usage needs of users with diopters ranging from +2D to -5D.

[0052] When the visual system is in the first state, the refractive power of the visual system is +2D, which is suitable for users with a refractive power of +2D; when the visual system is in the second state, the refractive power of the visual system is -5D, which is suitable for users with a refractive power of -5D. When the sign of the refractive power is negative, it indicates that the user is a myopic user; when the sign of the refractive power is positive, it indicates that the user is a hyperopic user; the specific value of the refractive power indicates the refractive power of the user. For example, a refractive power of +1D indicates that the user's hyperopia is approximately 100 degrees, and a refractive power of -1D indicates that the user's myopia is approximately 100 degrees.

[0053] It should be understood that the visual system having two states (for example, the first state and the second state) is merely exemplary, and the visual system may also have at least one other state besides the first state and the second state. When the visual system is in other states, the refractive power of the visual system is between +2D and -5D. The present disclosure does not specifically limit the number of states that the visual system has.

[0054] In an exemplary embodiment, the visual system has different virtual image distances in the first state and the second state, and the virtual image distance may be, for example, the on-axis distance from the virtual image formed by the image light from the second side at a predetermined position to the aperture stop.

[0055] In an exemplary embodiment, the visual system may satisfy: 1.15 ≤ fg / f2 ≤ 1.50, 1.55 < ΔL / Δf < 2.1, where fg is the combined focal length of the first lens, the reflective polarizing element, and the quarter-wave plate, f2 is the effective focal length of the second lens, ΔL is the movable distance of the second lens when the visual system switches between the first state and the second state, and Δf is the difference between the total effective focal length of the visual system in the first state and the total effective focal length of the visual system in the second state. By constraining fg / f2 and ΔL / Δf within reasonable ranges respectively, the visual system can be switched between the first state and the second state to achieve diopter adjustment of the visual system. For example, the diopter of the visual system is adjusted between +2D and -5D, and the visual system has good MTF values in different states, enabling users with different diopters (for example, users with diopters between +2D and -5D) to see clear images.

[0056] In an exemplary embodiment, the visual system may satisfy: 6.65 < TD / ΔL < 7.8, where TD is the on-axis distance from the first side surface of the first lens to the second side surface of the third lens, and ΔL is the movable distance of the second lens when the visual system switches between the first state and the second state. By controlling the above conditional expression, the body length of the visual system and the movable distance of the second lens can be constrained, such that the second lens has a larger movable distance during the diopter adjustment process of the visual system, and the structural design space of the visual system is larger, which is beneficial to improving the processability of the visual system.

[0057] In an exemplary embodiment, the visual system may satisfy: 8.64 mm ≤ L13 ≤ 9.43 mm, where L13 is the on-axis distance from the second side surface of the first lens to the first side surface of the third lens. By constraining the on-axis distance from the second side surface of the first lens to the first side surface of the third lens within a reasonable range, the second lens can have sufficient movable space during the diopter adjustment process of the visual system.

[0058] In an exemplary embodiment, the visual system may satisfy: 5.15 < EPD / Δf < 6.8, where EPD is the entrance pupil diameter of the visual system, and Δf is the difference between the total effective focal length of the visual system in the first state and the total effective focal length of the visual system in the second state. By controlling the above conditional expression, the difference between the total effective focal length of the visual system in the first state and the total effective focal length of the visual system in the second state can be constrained within a reasonable range to achieve diopter adjustment of the visual system (for example, the diopter is adjusted between +2D and -5D), and enable users with different diopters (for example, users with diopters between +2D and -5D) to see clear images.

[0059] In an exemplary embodiment, the visual system may satisfy: 2.15 mm < ΔL < 2.45 mm, where ΔL is the movable distance of the second lens when the visual system switches between the first state and the second state. By constraining the movable distance of the second lens when the visual system switches between the first state and the second state within a reasonable range, the second lens can have a sufficient movable distance during the diopter adjustment process of the visual system, and the main body length of the visual system can be reduced as much as possible, which is conducive to miniaturization of the visual system.

[0060] In an exemplary embodiment, the visual system may satisfy: 3.0≤fm / CT2≤3.33, wherein fm is the total effective focal length of the visual system when it is in the first state, and CT2 is the center thickness of the second lens on the optical axis. By constraining the ratio of the total effective focal length of the visual system when it is in the first state to the center thickness of the second lens on the optical axis within a reasonable range, the visual system as a whole can be made thinner and lighter, and the moving space required for the second lens during the diopter adjustment process of the visual system can be reduced.

[0061] In an exemplary embodiment, the visual system may satisfy: 5.1<(CT1+CTR+CTQ) / T12n<6.4, wherein CT1 is the center thickness of the first lens on the optical axis, CTR is the center thickness of the reflective polarizing element on the optical axis, CTQ is the center thickness of the quarter wave plate on the optical axis, and T12n is the on-axis distance from the second side of the first lens to the first side of the second lens when the visual system is in the second state. When the visual system is in the second state, the on-axis distance from the second side of the first lens to the first side of the second lens is the smallest. By controlling the above conditional expression, the center thickness of the first lens, the reflective polarizing element, and the quarter wave plate can be constrained, the main body length of the visual system can be reduced, and it is conducive to miniaturization of the visual system; at the same time, the on-axis distance from the second side of the first lens to the first side of the second lens when the visual system is in the second state can also be limited to avoid interference between the first lens and the second lens, and to allow a certain structural design space between the first lens and the second lens.

[0062] In an exemplary embodiment, the visual system may satisfy: 1.07≤CT3 / T23n≤1.41, wherein CT3 is the center thickness of the third lens on the optical axis, and T23n is the on-axis distance from the second side surface of the second lens to the first side surface of the third lens when the visual system is in the second state. By controlling the above conditional expression, the second lens can have sufficient movable space during the diopter adjustment process of the visual system, and the distance between the second lens and the third lens can be reduced as much as possible, the distance between the first lens and the third lens can be reduced, and the main body length of the visual system can be reduced, which is conducive to miniaturization of the visual system.

[0063] In an exemplary embodiment, the visual system may satisfy: 7.36 ≤ f1 / fn ≤ 10.40, where f1 is the effective focal length of the first lens and fn is the total effective focal length of the visual system in the second state. By constraining the ratio of the effective focal length of the first lens to the total effective focal length of the visual system in the second state within a reasonable range, the first lens can converge light better, while meeting the imaging requirements and reducing the sensitivity tolerance of the visual system.

[0064] In an exemplary embodiment, the visual system may satisfy: -2.6 < f3 / R6 < -1.8, where f3 is the effective focal length of the third lens and R6 is the radius of curvature of the second side surface of the third lens. By constraining the ratio of the effective focal length of the third lens to the radius of curvature of the second side surface of the third lens within a reasonable range, the angular change of light when passing through the first and second side surfaces of the third lens can be within a certain range, improving the relative illuminance of light in a large field of view.

[0065] In an exemplary embodiment, the visual system may satisfy: 5.35 < fm / T12m < 5.75, where fm is the total effective focal length of the visual system in the first state and T12m is the axial distance from the second side surface of the first lens to the first side surface of the second lens in the first state of the visual system. By controlling the above conditional expression, the second lens can have sufficient movable space during the diopter adjustment of the visual system, and the distance between the first lens and the second lens can be reduced as much as possible, the distance between the first lens and the third lens can be reduced, and the body length of the visual system can be reduced, which is beneficial to the miniaturization of the visual system.

[0066] In an exemplary embodiment, the visual system may satisfy: -18.65 ≤ R4 / (T23m + T23n) ≤ -12.83, where R4 is the radius of curvature of the second side surface of the second lens, T23m is the axial distance from the second side surface of the second lens to the first side surface of the third lens in the first state of the visual system, and T23n is the axial distance from the second side surface of the second lens to the first side surface of the third lens in the second state of the visual system. By controlling the above conditional expression, the shape of the second lens and the distances between the second lens and the first lens and the third lens can be constrained, improving the processability of the second lens, and reducing the body length of the visual system, which is beneficial to the miniaturization of the visual system.

[0067] In an exemplary embodiment, the visual system may satisfy: 3.09≤f2 / (fm+fn)≤3.30, where f2 is the effective focal length of the second lens, fm is the total effective focal length when the visual system is in the first state, and fn is the total effective focal length when the visual system is in the second state. By constraining the ratio of the effective focal length of the second lens to the sum of the total effective focal lengths of the visual system in the first state and the second state within a reasonable range, the second lens can better converge the light, and the sensitivity tolerance of the visual system can be reduced while meeting the imaging requirements.

[0068] In an exemplary embodiment, the visual system may satisfy: -11.52≤R4 / CT2≤-10.39, where R4 is the radius of curvature of the second side surface of the second lens, and CT2 is the center thickness of the second lens on the optical axis. By constraining the radius of curvature of the second side surface of the second lens and the center thickness of the second lens on the optical axis within a reasonable range, the overall shape of the second lens can be constrained, thereby constraining the thickness ratio of the second lens and improving the processability of the second lens.

[0069] According to the above-mentioned embodiment of the visual system of the present disclosure, multiple lenses may be used, such as the three lenses described above. By reasonably allocating the parameters of the reflective polarizing element, the quarter-wave plate, and each lens, the main body length of the visual system can be reduced, the imaging quality of the visual system can be improved, and the diopter adjustment of the visual system can be achieved, so that users with a diopter between +2D and -5D can see clear images. The visual system configured as above has the characteristics of diopter adjustment, lightness and thinness, and good imaging quality, and can well meet the use requirements of various portable electronic products in projection scenarios.

[0070] In an embodiment of the present disclosure, at least one of the surfaces of the first lens, the second lens, and the third 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.

[0071] The second aspect of the present disclosure provides such a visual system, which includes, in order from the first side to the second side along the optical axis, a first lens with positive optical power, a reflective polarizing element, a quarter wave plate, a second lens with positive optical power, a partial reflective element, and a third lens with positive optical power. The first side surface of the first lens is convex, and the second side surface is flat. The second side surface of the second lens is convex. The second side surface of the third lens is convex. Among them, the position of the first lens on the optical axis relative to the image plane of the second side is fixed, and the distance of the second lens on the optical axis relative to the first lens is adjustable. The number of lenses with optical power in the visual system is three.

[0072] The visual system satisfies: 1.15≤fg / f2≤1.50, 8.64mm≤L13≤9.43mm, wherein fg is the combined focal length of the first lens, the reflective polarizing element and the quarter wave plate, f2 is the effective focal length of the second lens, and L13 is the on-axis distance from the second side of the first lens to the first side of the third lens. The visual system provided by the present disclosure can realize the refraction of the light path by using the reflective polarizing element, the quarter wave plate and the partial reflective element, and the visual system can be switched between the first state and the second state by moving the second lens, so as to realize the diopter adjustment of the visual system. At the same time, by constraining fg / f2 and L13 within a reasonable range respectively, the second lens can have sufficient movable space during the diopter adjustment process of the visual system, and the visual system has a good MTF value in different states, so that users with different diopters (for example, users with diopters between +2D and -5D) can see clear imaging.

[0073] However, those skilled in the art should understand that, without departing from the technical solution claimed in the present disclosure, the number of lenses constituting the visual system can be changed to obtain the various results and advantages described in this specification.

[0074] Specific embodiments of the visual system applicable to the above-mentioned embodiments are further described below with reference to the accompanying drawings. Example 1

[0075] The following reference Figure 1 , Figure 2 , Figure 3 and Figure 4 Describe the visual system of Example 1 of the present disclosure.

[0076] like Figure 1 and Figure 3As shown, the visual system may include a first lens E1, a reflective polarizing element RP, a quarter wave plate QWP, a second lens E2, a partial reflective element BS and a third lens E3 arranged in sequence from the first side to the second side along the optical axis. The stop STO may be located on the object 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.

[0077] The first lens E1 has positive optical power, its first side surface S1 is convex, and the second side surface S2 is a plane. The second lens E2 has positive optical power, its first side surface S3 is convex, and the second side surface S4 is convex. The third lens E3 has positive optical power, its first side surface S5 is concave, and the second side surface S6 is convex. The reflective polarizing element RP and the quarter-wave plate QWP are attached to the second side surface S2 of the first lens E1. The partially reflecting element BS is attached to the second side surface S4 of the second lens E2. It should be noted that the surfaces S1, S2, S3, S4, S5 and S6 are Figure 1 and Figure 3 Not shown.

[0078] In this example, the second side of the visual system may be provided with an image surface IMG, and the image surface IMG may be provided with a display screen, for example. Figure 1 and Figure 3 As shown, the image light from the image surface IMG passes through the third lens E3, the second lens E2, the quarter wave plate QWP and reaches the reflective polarizer RP in sequence, and then the first reflection occurs at the reflective polarizer RP. The light reflected for the first time passes through the quarter wave plate QWP, the second lens E2 and reaches the partial reflective element BS located on the second side of the second lens, and then the second reflection occurs at the partial reflective element BS. The light reflected for the second time passes through the second lens E2, the quarter wave plate QWP, the reflective polarizer RP, the first lens E1 to the aperture in sequence and finally forms an image at a predetermined position. For example, the light of the visual system after two reflections is finally projected to the user's pupil.

[0079] Table 1 shows the basic parameters of the visual 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 the components in the order of sequence number 15 to sequence number 1 and is finally projected to the user's pupil.

[0080] Table 1

[0081]

[0082] In this embodiment, the first side surface S1 of the first lens E1, the first side surface S3 and the second side surface S4 of the second lens E2, and the first side surface S5 and the second side surface S6 of the third lens E3 are aspherical surfaces, and the surface shape of each aspherical surface can be defined by but not limited to the following formula:

[0083] (1)

[0084] in, 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 gives the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the surfaces S1, S3, S4, S5 and S6 that can be used in Example 1.

[0085] Table 2

[0086]

[0087] In this embodiment, the visual system has a first state (eg, Figure 1 ) and the second state (e.g., Figure 3 ). The virtual image distance of the visual system is W1, the spacing distance between the quarter wave plate and the second lens is W2, and the spacing distance between the second lens and the third lens is W3. W1, W2, and W3 are variables that may change as the state of the visual system changes.

[0088] Table 3 shows the values ​​of W1, W2 and W3 of Example 1 under different states of the visual system.

[0089] Table 3

[0090]

[0091] Figure 2 The modulation transfer function curve of Example 1 when the visual system is in the first state is shown. Figure 4 The modulation transfer function curve of the visual system of Example 1 when it is in the second state is shown. Figure 2 and Figure 4 It can be seen that the visual system provided in Example 1 can achieve good imaging quality both in the first state and in the second state. Example 2

[0092] The following reference Figure 5 , Figure 6 , Figure 7 and Figure 8 Describe the visual system of Example 2 of the present disclosure.

[0093] like Figure 5 and Figure 7As shown, the visual system may include a first lens E1, a reflective polarizing element RP, a quarter wave plate QWP, a second lens E2, a partial reflective element BS and a third lens E3 arranged in sequence from the first side to the second side along the optical axis. The stop STO may be located on the object 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.

[0094] The first lens E1 has positive optical power, its first side surface S1 is convex, and the second side surface S2 is a plane. The second lens E2 has positive optical power, its first side surface S3 is convex, and the second side surface S4 is convex. The third lens E3 has positive optical power, its first side surface S5 is concave, and the second side surface S6 is convex. The reflective polarizing element RP and the quarter-wave plate QWP are attached to the second side surface S2 of the first lens E1. The partially reflecting element BS is attached to the second side surface S4 of the second lens E2. It should be noted that the surfaces S1, S2, S3, S4, S5 and S6 are Figure 5 and Figure 7 Not shown.

[0095] In this example, the second side of the visual system may be provided with an image surface IMG, and the image surface IMG may be provided with a display screen, for example. Figure 5 and Figure 7 As shown, the image light from the image surface IMG passes through the third lens E3, the second lens E2, the quarter wave plate QWP and reaches the reflective polarizer RP in sequence, and then the first reflection occurs at the reflective polarizer RP. The light reflected for the first time passes through the quarter wave plate QWP, the second lens E2 and reaches the partial reflective element BS located on the second side of the second lens, and then the second reflection occurs at the partial reflective element BS. The light reflected for the second time passes through the second lens E2, the quarter wave plate QWP, the reflective polarizer RP, the first lens E1 to the aperture in sequence and finally forms an image at a predetermined position. For example, the light of the visual system after two reflections is finally projected to the user's pupil.

[0096] Table 4 shows the basic parameters of the visual system of Example 2, 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 the components in the order of sequence number 15 to sequence number 1 and is finally projected to the user's pupil.

[0097] Table 4

[0098]

[0099] In this embodiment, the first side surface S1 of the first lens E1, the first side surface S3 and the second side surface S4 of the second lens E2, and the first side surface S5 and the second side surface S6 of the third lens E3 are aspherical surfaces. Table 5 shows the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the surfaces S1, S3, S4, S5 and S6 that can be used in Embodiment 2.

[0100] Table 5

[0101]

[0102] In this embodiment, the visual system has a first state (eg, Figure 5 ) and the second state (e.g., Figure 7 ). W1, W2 and W3 are variables that may change as the state of the visual system changes.

[0103] Table 6 shows the values ​​of W1, W2 and W3 of Example 2 under different states of the visual system.

[0104] Table 6

[0105]

[0106] Figure 6 The modulation transfer function curve of Example 2 when the visual system is in the first state is shown. Figure 8 The modulation transfer function curve of the visual system of Example 2 when it is in the second state is shown. Figure 6 and Figure 8 It can be seen that the visual system provided in Example 2 can achieve good imaging quality both in the first state and in the second state. Example 3

[0107] The following reference Fig. 9 , Fig.10 , Fig.11 and Fig.12 Describe the visual system of Example 3 of the present disclosure.

[0108] like Fig. 9 and Fig.11 As shown, the visual system may include a first lens E1, a reflective polarizing element RP, a quarter wave plate QWP, a second lens E2, a partial reflective element BS and a third lens E3 arranged in sequence from the first side to the second side along the optical axis. The stop STO may be located on the object 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.

[0109] The first lens E1 has positive optical power, its first side surface S1 is convex, and the second side surface S2 is a plane. The second lens E2 has positive optical power, its first side surface S3 is concave, and the second side surface S4 is convex. The third lens E3 has positive optical power, its first side surface S5 is concave, and the second side surface S6 is convex. The reflective polarizing element RP and the quarter-wave plate QWP are attached to the second side surface S2 of the first lens E1. The partially reflecting element BS is attached to the second side surface S4 of the second lens E2. It should be noted that the surfaces S1, S2, S3, S4, S5 and S6 are Fig. 9 and Fig.11 Not shown.

[0110] In this example, the second side of the visual system may be provided with an image surface IMG, and the image surface IMG may be provided with a display screen, for example. Fig. 9 and Fig.11 As shown, the image light from the image surface IMG passes through the third lens E3, the second lens E2, the quarter wave plate QWP and reaches the reflective polarizer RP in sequence, and then the first reflection occurs at the reflective polarizer RP. The light reflected for the first time passes through the quarter wave plate QWP, the second lens E2 and reaches the partial reflective element BS located on the second side of the second lens, and then the second reflection occurs at the partial reflective element BS. The light reflected for the second time passes through the second lens E2, the quarter wave plate QWP, the reflective polarizer RP, the first lens E1 to the aperture in sequence and finally forms an image at a predetermined position. For example, the light of the visual system after two reflections is finally projected to the user's pupil.

[0111] Table 7 shows the basic parameters of the visual system of Example 3, 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 the components in the order of sequence number 15 to sequence number 1 and is finally projected to the user's pupil.

[0112] Table 7

[0113]

[0114] In this embodiment, the first side surface S1 of the first lens E1, the first side surface S3 and the second side surface S4 of the second lens E2, and the first side surface S5 and the second side surface S6 of the third lens E3 are aspherical surfaces. Table 8 shows the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the surfaces S1, S3, S4, S5 and S6 that can be used in Embodiment 3.

[0115] Table 8

[0116]

[0117] In this embodiment, the visual system has a first state (eg, Fig. 9 ) and the second state (e.g., Fig.11 ). W1, W2 and W3 are variables that may change as the state of the visual system changes.

[0118] Table 9 shows the values ​​of W1, W2 and W3 of Example 3 under different states of the visual system.

[0119] Table 9

[0120]

[0121] Fig.10 The modulation transfer function curve of Example 3 when the visual system is in the first state is shown. Fig.12 The modulation transfer function curve of the visual system of Example 3 when it is in the second state is shown. Fig.10 and Fig.12 It can be seen that the visual system provided in Example 3 can achieve good imaging quality both in the first state and in the second state. Example 4

[0122] The following reference Fig.13 , Fig.14 , Fig.15 and Fig.16 Describe the visual system of Example 4 of the present disclosure.

[0123] like Fig.13 and Fig.15 As shown, the visual system may include a first lens E1, a reflective polarizing element RP, a quarter wave plate QWP, a second lens E2, a partial reflective element BS and a third lens E3 arranged in sequence from the first side to the second side along the optical axis. The stop STO may be located on the object 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.

[0124] The first lens E1 has positive optical power, and its first side surface S1 is convex, and the second side surface S2 is a plane. The second lens E2 has positive optical power, and its first side surface S3 is convex, and the second side surface S4 is convex. The third lens E3 has positive optical power, and its first side surface S5 is a plane, and the second side surface S6 is a convex surface. The reflective polarizing element RP and the quarter-wave plate QWP are attached to the second side surface S2 of the first lens E1. The partially reflecting element BS is attached to the second side surface S4 of the second lens E2. It should be noted that the surfaces S1, S2, S3, S4, S5 and S6 are Fig.13 and Fig.15 Not shown.

[0125] In this example, the second side of the visual system may be provided with an image surface IMG, and the image surface IMG may be provided with a display screen, for example. Fig.13 and Fig.15 As shown, the image light from the image surface IMG passes through the third lens E3, the second lens E2, the quarter wave plate QWP in sequence and reaches the reflective polarizer RP, and then the first reflection occurs at the reflective polarizer RP. The light reflected for the first time passes through the quarter wave plate QWP, the second lens E2 and reaches the partial reflective element BS located on the second side of the second lens, and then the second reflection occurs at the partial reflective element BS. The light reflected for the second time passes through the second lens E2, the quarter wave plate QWP, the reflective polarizer RP, the first lens E1 to the aperture in sequence and finally forms an image at a predetermined position. For example, the light of the visual system after two reflections is finally projected to the user's pupil. A protective glass E4 may also be provided between the image surface IMG and the third lens E3.

[0126] Table 10 shows the basic parameters of the visual 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 the components in the order of sequence number 17 to sequence number 1 and is finally projected to the user's pupil.

[0127] Table 10

[0128]

[0129] In this embodiment, the first side surface S1 of the first lens E1, the first side surface S3 and the second side surface S4 of the second lens E2, and the first side surface S5 and the second side surface S6 of the third lens E3 are aspherical surfaces. Table 11 lists the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the surfaces S1, S3, S4, S5 and S6 that can be used in Embodiment 4.

[0130] Table 11

[0131]

[0132] In this embodiment, the visual system has a first state (eg, Fig.13 ) and the second state (e.g., Fig.15 ). W1, W2 and W3 are variables that may change as the state of the visual system changes.

[0133] Table 12 shows the values ​​of W1, W2 and W3 of Example 4 under different states of the visual system.

[0134] Table 12

[0135]

[0136] Fig.14 The modulation transfer function curve of Example 4 when the visual system is in the first state is shown. Fig.16 The modulation transfer function curve of the visual system of Example 4 when it is in the second state is shown. Fig.14 and Fig.16 It can be seen that the visual system provided in Example 4 can achieve good imaging quality both in the first state and in the second state.

[0137] Table 13 gives the basic parameters of each of Examples 1 to 4, such as the values ​​of fm, fn, f1, f2, f3, fg, EPD, TD and Δf.

[0138] Table 13

[0139]

[0140] Table 14 shows the values ​​of the conditional expressions of each of Examples 1 to 4.

[0141] Table 14

[0142]

[0143] The present disclosure also provides an optical device, which can be an independent projection device such as a projector, or a projection module integrated in a mobile electronic device such as a virtual reality device or an augmented reality device. The optical device is equipped with the visual system described above.

[0144] The above description is only a preferred embodiment of the present disclosure 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 disclosure 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 the present disclosure (but not limited to) by each other.

Claims

1. A visual system, characterized in that: The method comprises, in order from the first side to the second side along the optical axis: A first lens having positive optical power, wherein the first side surface is convex and the second side surface is flat; Reflective polarizing element; Quarter wave plate; a second lens having positive optical power, wherein the second side surface of the second lens is convex; a partially reflective element; and a third lens element having positive power, wherein the second side surface of the third lens element is convex; Wherein, the position of the first lens on the optical axis relative to the image plane of the second side is fixed, and the distance of the second lens on the optical axis relative to the first lens is adjustable; The number of lenses having optical power in the visual system is three; The first side is a human eye side, and the second side is a display screen side; The visual system satisfies: 1.15≤fg / f2≤1.50, 1.55<ΔL / Δf<2.1, wherein fg is the combined focal length of the first lens, the reflective polarizing element and the quarter-wave plate, f2 is the effective focal length of the second lens, ΔL is the movable distance of the second lens when the visual system switches between the first state and the second state, and Δf is the difference between the total effective focal length when the visual system is in the first state and the total effective focal length when the visual system is in the second state.

2. The visual system according to claim 1, wherein: The visual system also meets the following requirements: 6.65 <TD / ΔL<7.8, Wherein, TD is the on-axis distance from the first side surface of the first lens to the second side surface of the third lens, and ΔL is the movable distance of the second lens when the visual system switches between the first state and the second state.

3. The visual system according to claim 1, wherein: The visual system also meets the following requirements: 8.64mm≤L13≤9.43mm, Wherein, L13 is the on-axis distance from the second side surface of the first lens to the first side surface of the third lens.

4. The visual system according to claim 1, wherein: The visual system also meets the following requirements: 5.15 <EPD / Δf<6.8, Wherein, EPD is the entrance pupil diameter of the visual system, and Δf is the difference between the total effective focal length when the visual system is in the first state and the total effective focal length when the visual system is in the second state.

5. The visual system according to claim 1, wherein: The visual system also meets the following requirements: 2.15mm<ΔL<2.45mm, Wherein, ΔL is a movable distance of the second lens when the visual system switches between the first state and the second state.

6. The visual system according to any one of claims 1 to 5, wherein: The visual system also meets the following requirements: 3.0≤fm / CT2≤3.33, Wherein, fm is the total effective focal length of the visual system when it is in the first state, and CT2 is the center thickness of the second lens on the optical axis.

7. The visual system according to any one of claims 1 to 5, wherein: The visual system also meets the following requirements: 5.1<(CT1+CTR+CTQ) / T12n<6.4, Among them, CT1 is the center thickness of the first lens on the optical axis, CTR is the center thickness of the reflective polarizing element on the optical axis, CTQ is the center thickness of the quarter wave plate on the optical axis, and T12n is the on-axis distance from the second side of the first lens to the first side of the second lens when the visual system is in the second state.

8. The visual system according to any one of claims 1 to 5, wherein: The visual system also meets the following requirements: 1.07≤CT3 / T23n≤1.41, Among them, CT3 is the center thickness of the third lens on the optical axis, and T23n is the on-axis distance from the second side of the second lens to the first side of the third lens when the visual system is in the second state.

9. The visual system according to any one of claims 1 to 5, wherein: The visual system also meets the following requirements: 7.36≤f1 / fn≤10.40, Wherein, f1 is the effective focal length of the first lens, and fn is the total effective focal length when the visual system is in the second state.

10. The visual system according to any one of claims 1 to 5, wherein: The visual system also meets the following requirements: -2.6 <f3 / R6<-1.8, Wherein, f3 is the effective focal length of the third lens, and R6 is the curvature radius of the second side surface of the third lens.

11. The visual system according to any one of claims 1 to 5, wherein: The visual system also meets the following requirements: 5.35 <fm / T12m<5.75, Wherein, fm is the total effective focal length when the visual system is in the first state, and T12m is the on-axis distance from the second side of the first lens to the first side of the second lens when the visual system is in the first state.

12. The visual system according to any one of claims 1 to 5, wherein: The visual system also meets the following requirements: -18.65≤R4 / (T23m+T23n)≤-12.83, Among them, R4 is the curvature radius of the second side surface of the second lens, T23m is the on-axis distance from the second side surface of the second lens to the first side surface of the third lens when the visual system is in the first state, and T23n is the on-axis distance from the second side surface of the second lens to the first side surface of the third lens when the visual system is in the second state.

13. The visual system according to any one of claims 1 to 5, wherein: The visual system also meets the following requirements: 3.09≤f2 / (fm+fn)≤3.30, Among them, f2 is the effective focal length of the second lens, fm is the total effective focal length when the visual system is in the first state, and fn is the total effective focal length when the visual system is in the second state.

14. The visual system according to any one of claims 1 to 5, wherein: The visual system also meets the following requirements: -11.52≤R4 / CT2≤-10.39, Wherein, R4 is the curvature radius of the second side surface of the second lens, and CT2 is the center thickness of the second lens on the optical axis.

Images