Optical system

Abstract

The application discloses an optical system, which comprises a lens barrel and a first element group, a second element group and a third element group arranged in sequence from a first side to a second side along an optical axis in the lens barrel, wherein the first element group comprises a first lens and a reflective polarizing element; the second element group comprises a second lens and a quarter-wave plate; the third element group comprises a third lens, the third lens has a positive refractive power sign; at least one lens among the first lens, the second lens and the third lens has an aspheric surface; and an inner diameter of a first side end surface of the lens barrel is less than 45.0 mm, and the inner diameter d0s of the first side end surface of the lens barrel, a total effective focal length f of the optical system and a maximum field of view angle FOV of the optical system satisfy: 2.0 < d0s / (f x tan(FOV / 2)) < 3.0.

Description

Technical Field

[0001] This application relates to the field of optical devices, specifically to a three-piece optical system. Background Technology

[0002] Virtual Reality (VR) technology is a technology that simulates real-world scenarios and provides a highly immersive experience through computer graphics, sound, and other sensory inputs. It holds immense promise for applications in entertainment, education, arts and culture, remote collaboration, and healthcare. The resolution of a VR device is a crucial factor affecting the user's immersion. However, in the actual design of VR device optical systems, inconsistencies in the end-face aperture and field of view can lead to poor resolution. Furthermore, an inappropriate end-face aperture can result in unsuitable radial dimensions and poor fit with the user, thus impacting the user's immersion experience. Summary of the Invention

[0003] This application provides an optical system that can at least solve or partially solve at least one problem or other problems existing in the prior art.

[0004] One aspect of this application provides an optical system comprising a lens barrel and a first element group, a second element group, and a third element group arranged sequentially along the optical axis from a first side to a second side within the lens barrel. The first element group includes a first lens and a reflective polarizing element; the second element group includes a second lens and a quarter-wave plate; the third element group includes a third lens with a positive refractive power; at least one of the first, second, and third lenses has an aspherical surface; and the inner diameter of the first side end face of the lens barrel is less than 45.0 mm, and the inner diameter d0s of the first side end face of the lens barrel, the total effective focal length f of the optical system, and the maximum field of view (FOV) of the optical system satisfy: 2.0. <d0s / (f×tan(FOV / 2))<3.0。

[0005] According to an exemplary embodiment of this application, the inner diameter d0s of the first side end face of the lens barrel, the outer diameter D0s of the first side end face of the lens barrel, and the total effective focal length f of the optical system satisfy: 0.5 < π × ((D0s / 2) 2 -(d0s / 2) 2 ) / f 2 <5.0.

[0006] According to an exemplary embodiment of this application, the inner diameter d0s of the first side end face of the lens barrel, the outer diameter D0s of the first side end face of the lens barrel, and the length L of the lens barrel in the direction of the optical axis satisfy: 0.3 < (D0s - d0s) / L < 2.0.

[0007] According to an exemplary embodiment of this application, the opening bevel angle α of the lens barrel relative to the first side end face satisfies: 50.0° < α < 150.0°.

[0008] According to an exemplary embodiment of this application, the angle α of the opening slope of the lens barrel relatively close to the first side end face satisfies the maximum field of view (FOV) of the optical system as follows: 1.0 < α / FOV < 6.0.

[0009] According to an exemplary embodiment of this application, the minimum inner diameter ds of the lens barrel and the total effective focal length f of the optical system satisfy: 1.0 <ds / f<3.0。

[0010] According to an exemplary embodiment of this application, the optical system further includes a second isolator disposed on and in contact with the second side surface of the second lens, wherein the effective focal length f2 of the second element group, the refractive index N2 of the second lens, and the refractive index N of the quarter-wave plate are... Q The distance EP02 between the first side end face of the lens barrel and the second spacer along the optical axis satisfies: -35.0. <f2×(N2+N Q ) / EP02<30.0.

[0011] According to an exemplary embodiment of this application, the optical system further includes a second isolator disposed on and in contact with the second side surface of the second lens, wherein the radius of curvature R3 of the first side surface of the second lens, the radius of curvature R4 of the second side surface of the second lens, the inner diameter d2s of the first side surface of the second isolator and the outer diameter D2s of the first side surface of the second isolator satisfy: |R3-R4| / (d2s+D2s)<10.0.

[0012] According to an exemplary embodiment of this application, the optical system further includes a second isolator disposed on and in contact with the second side surface of the second lens. The center thickness CT3 of the third lens on the optical axis, the air gap T23 between the second element group and the third element group on the optical axis, and the maximum thickness CP2 of the second isolator satisfy: 1.0 <CT3 / (CP2+T23)<10.0。

[0013] According to an exemplary embodiment of this application, the optical system further includes a second isolator disposed on and in contact with the second side surface of the second lens, wherein the effective focal length f2 of the second element group, the effective focal length f3 of the third element group, the inner diameter d2s of the first side surface of the second isolator, and the inner diameter d2m of the second side surface of the second isolator satisfy: -5.0 <f2 / d2s-f3 / d2m<0。

[0014] According to an exemplary embodiment of this application, the optical system further includes a first isolator and a second isolator. The first isolator is disposed on and in contact with a second side surface of the first lens, and the second isolator is disposed on and in contact with a second side surface of the second lens. The dispersion coefficient V2 of the second lens and the dispersion coefficient V of the quarter-wave plate are... Q The spacing EP12 between the first and second isolators along the optical axis and the effective focal length f2 of the second element group satisfy: -5.0 < (V2 + V Q )×EP12 / f2<0.

[0015] According to an exemplary embodiment of this application, the optical system further includes a first isolator disposed on and in contact with the second side of the first lens, wherein the center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, the refractive index N1 of the first lens, and the refractive index N of the reflective polarizing element are... R The distance EP01 between the first side end face of the lens barrel and the first spacer along the optical axis satisfies: 3.0 < (CT1 + CT2) × (N1 + N R ) / EP01<6.0.

[0016] According to an exemplary embodiment of this application, the optical system further includes a first isolator disposed on and in contact with the second side surface of the first lens, wherein the effective focal length f1 of the first element group and the inner diameter d1s of the first side surface of the first isolator satisfy: 1.0 <f1 / d1s<3.0。

[0017] The optical system provided in this application is configured as a three-element reflex system, which can rationally distribute the refractive power of each element group, reduce the length of the projection device using the optical system, improve the aberration correction capability of the optical system, and enhance the imaging quality of the optical system. This application can also constrain the opening size of the first side end face of the lens barrel to less than 45.0 mm while ensuring that the field of view of the optical system meets the requirements, thereby reducing the radial dimension of the opening of the first side end face of the lens barrel to better match the user's eyes, improve the resolution of the optical system, and thus enhance the user's immersion. In addition, this application also improves the spherical aberration of the optical system and corrects image plane curvature and distortion aberrations by configuring at least one surface of at least one of the first lens, the second lens, and the third lens as an aspherical surface. Attached Figure Description

[0018] 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:

[0019] Figure 1 A schematic diagram of the parameters of the optical system according to this application is shown;

[0020] Figure 2 A schematic diagram of the structure of an optical system according to Embodiment 1 of the first embodiment of this application is shown;

[0021] Figure 3 A schematic diagram of the structure of an optical system according to Embodiment 2 of the first embodiment of this application is shown;

[0022] Figure 4 A schematic diagram of the structure of an optical system according to Embodiment 3 of the first embodiment of this application is shown;

[0023] Figures 5A to 5C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to the first embodiment of this application are shown respectively.

[0024] Figure 6 A schematic diagram of the structure of an optical system according to Embodiment 1 of the second embodiment of this application is shown;

[0025] Figure 7 A schematic diagram of the structure of an optical system according to Embodiment 2 of the second embodiment of this application is shown;

[0026] Figure 8 A schematic diagram of the structure of an optical system according to Embodiment 3 of the second embodiment of this application is shown;

[0027] Figures 9A to 9C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to the second embodiment of this application are shown respectively.

[0028] Figure 10 A schematic diagram of the structure of an optical system according to Embodiment 1 of the third embodiment of this application is shown;

[0029] Figure 11 A schematic diagram of the structure of an optical system according to Embodiment 2 of the third embodiment of this application is shown;

[0030] Figure 12 A schematic diagram of the structure of an optical system according to Embodiment 3 of the third embodiment of this application is shown; and

[0031] Figures 13A to 13C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to the third embodiment of this application are shown respectively. Detailed Implementation

[0032] 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.

[0033] 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.

[0034] 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 drawn strictly to scale.

[0035] In this paper, 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 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 side) is called the second side surface of the lens.

[0036] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising" as 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 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.

[0037] 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.

[0038] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] The features, principles and other aspects of this application are described in detail below.

[0040] like Figures 2 to 4 , Figures 6 to 8 as well as Figures 10 to 12 As shown, an optical system according to an exemplary embodiment of this application may include a lens barrel and a first element group, a second element group, and a third element group arranged sequentially along the optical axis from a first side to a second side within the lens barrel. The first element group may, for example, include a first lens and a reflective polarizing element; the second element group may, for example, include a second lens and a quarter-wave plate; and the third element group may, for example, include a third lens. The quarter-wave plate, in conjunction with the reflective polarizing element, can achieve optical path reflection, which is beneficial for reducing the overall length and volume of the optical system.

[0041] In an exemplary embodiment, the optical system may further include a partially reflective layer, which may be attached, for example, to a first or second side of the third lens. The partially reflective layer has a semi-transmissive and semi-reflective effect on light.

[0042] In an exemplary embodiment, the first side may be, for example, the human eye side, and the second side may be, for example, the display side. Accordingly, the first side of each element (first lens, second lens, third lens, reflective polarizing element, quarter-wave plate or partial reflective layer) may be referred to as the side near the human eye, and the second side may be referred to as the side near the display.

[0043] In an exemplary embodiment, the first side and / or the second side of the first lens are configured as planes. By constraining the shape of the first lens, the difficulty of assembling and attaching the reflective polarizing element can be reduced, thereby facilitating optical path reflection, reducing the overall length of the optical system, and contributing to the miniaturization of the optical system.

[0044] In an exemplary embodiment, at least one of the first, second, and third lenses has an aspherical surface. By configuring at least one surface of at least one of the first, second, and third lenses as aspherical, spherical aberration of the optical system can be improved, and image plane curvature and distortion aberrations can be corrected.

[0045] In an exemplary embodiment, the optical system may further include a second isolator disposed within the lens barrel, wherein the second isolator is positioned on a second side surface of the second lens and at least partially contacts the second side surface of the second lens. Proper use of the isolator can effectively mitigate stray light risks, reduce interference with image quality, and thereby improve the imaging quality of the optical system.

[0046] In other examples, the optical system may also include a first isolator disposed within the lens barrel, wherein the first isolator is disposed on a second side of the first lens and at least partially contacts the second side of the first lens.

[0047] In an exemplary embodiment, the optical system may further include an aperture, which may be disposed, for example, between the first side and the first lens. The user's eye can view the image projected by the display on the second side at the position of the aperture. That is, the image light on the display passes through the third lens, the quarter-wave plate, the second lens, the reflective polarizing element, the first lens and other multiple refractions and reflections, and finally projects onto the user's eye.

[0048] In an exemplary embodiment, a display may be disposed on the second side of the optical system. The image light from the display may sequentially pass through the third lens, the quarter-wave plate, the second lens, reach the reflective polarizing element, and then be reflected at the reflective polarizing element to form the first reflected image light. The first reflected image light passes through the second lens, the quarter-wave plate and reaches the partial reflection layer on the first side surface of the third lens, and then is reflected at the partial reflection layer to form the second reflected image light. The second reflected image light sequentially passes through the quarter-wave plate, the second lens, the reflective polarizing element, the first lens to the aperture (i.e., the position where the user's eye views the image). In other examples, the first reflected image light passes through the second lens, the quarter-wave plate, the third lens and reaches the partial reflection layer, and then is reflected at the partial reflection layer to form the second reflected image light. The second reflected image light sequentially passes through the third lens, the quarter-wave plate, the second lens, the reflective polarizing element, the first lens to the aperture (i.e., the position where the user's eye views the image). The optical system provided by the present application folds the required optical path by a combination of light reflection and refraction without affecting the projection quality, effectively shortening the body length of the optical system.

[0049] In an exemplary embodiment, the refractive power of the third lens has a positive sign. The inner diameter of the first side end surface of the lens barrel is less than 45.0 mm, and the inner diameter d0s of the first side end surface of the lens barrel, the total effective focal length f of the optical system, and the maximum field angle FOV of the optical system may satisfy: 2.0 < d0s / (f × tan(FOV / 2)) < 3.0. The optical system provided by the present application can reasonably distribute the refractive power of each element group, reduce the length of the projection device using the optical system, improve the aberration correction ability of the optical system, and improve the imaging quality of the optical system; it can also constrain the opening size of the first side end surface of the lens barrel within a range less than 45.0 mm while ensuring that the field angle of the optical system meets the requirements, reduce the radial dimension of the opening of the first side end surface of the lens barrel, better match the user's eye, improve the resolution of the optical system, and further enhance the user's immersion.

[0050] In an exemplary embodiment, the effective focal length f2 of the second element group, the refractive index N2 of the second lens, the refractive index N of the quarter-wave plate QThe interval EP02 between the first side end face of the lens barrel and the second spacer along the optical axis can satisfy: -35.0 < f2×(N2 + N Q ) / EP02 < 30.0. By controlling the above conditional expression, the effective focal length of the second element group can be restricted, the shape of the second lens can be effectively constrained, which helps the processing and forming of the second lens. And the quarter-wave plate can change the polarization state of light. By cooperating the quarter-wave plate with the reflective polarizing element, the refraction and reflection of the optical path can be realized, thereby reducing the body length of the optical system. At the same time, the edge thickness of the first lens, the second lens and / or the first spacer can also be controlled by restricting the interval between the first side end face of the lens barrel and the second spacer along the optical axis, which is beneficial to the forming of the first lens, the second lens and / or the first spacer.

[0051] In an exemplary embodiment, the radius of curvature R3 of the first side face of the second lens, the radius of curvature R4 of the second side face of the second lens, the inner diameter d2s of the first side face of the second spacer and the outer diameter D2s of the first side face of the second spacer can satisfy: |R3 - R4| / (d2s + D2s) < 10.0. In an example, 1.5 < |R3 - R4| / (d2s + D2s) < 7.0. By controlling the above conditional expression, the refractive power of the second element group can be restricted, so that the distortion of the optical system is within a reasonable range, improving the imaging quality of the optical system, and the surface shape of the second lens is constrained to control the deflection angle of light at the second lens, thereby reducing the sensitivity of the second lens. At the same time, the inner and outer diameters of the first side face of the second spacer can also be restricted to ensure the stable bearing between the second lens and the second spacer, enhancing the assembly stability of the optical system.

[0052] In an exemplary embodiment, the central thickness CT3 of the third lens on the optical axis, the air interval T23 between the second element group and the third element group on the optical axis and the maximum thickness CP2 of the second spacer can satisfy: 1.0 < CT3 / (CP2 + T23) < 10.0. In an example, 1.2 < CT3 / (CP2 + T23) < 6.5. By controlling the above conditional expression, the positions and sizes of the second lens, the second spacer and the third lens in space can be reasonably distributed, which is beneficial to controlling the spherical aberration and axial chromatic aberration introduced by the third lens and reducing the ghost image risk caused by internal reflection in the third lens.

[0053] In an exemplary embodiment, the dispersion coefficient V2 of the second lens, the dispersion coefficient V Q of the quarter-wave plate, the interval EP12 between the first spacer and the second spacer along the optical axis and the effective focal length f2 of the second element group can satisfy: -5.0 < (V2 + V Q )×EP12 / f2 < 0. In an example, -4.1 < (V2 + V Q) × EP12 / f2 < -2.5. By controlling the above conditional expression, it is possible to reasonably allocate the contributions of the second lens and the quarter-wave plate to the dispersion of the optical system, which is beneficial to improving the color purity of the imaging of the optical system and the sharpness of the indirect imaging; at the same time, it is also possible to limit the effective focal length of the second element group and the edge thickness of the second lens, effectively constrain the shape of the second lens, and optimize the light path, thereby improving the imaging quality of the optical system.

[0054] In an exemplary embodiment, the inner diameter d0s of the first side end face of the lens barrel, the outer diameter D0s of the first side end face of the lens barrel, and the total effective focal length f of the optical system may satisfy: 0.5 < π × ((D0s / 2) 2 - (d0s / 2) 2 ) / f 2 < 5.0. In an example, 1.4 < π × ((D0s / 2) 2 - (d0s / 2) 2 ) / f 2 < 4.5. By controlling the above conditional expression, it is possible to constrain both the imaging size and the imaging position of the optical system within a reasonable range, which is beneficial to enhancing the immersion feeling of the user when using the optical system.

[0055] In an exemplary embodiment, the inner diameter d0s of the first side end face of the lens barrel, the outer diameter D0s of the first side end face of the lens barrel, and the length L of the lens barrel in the direction of the optical axis may satisfy: 0.3 < (D0s - d0s) / L < 2.0. In an example, 0.5 < (D0s - d0s) / L < 1.0. By controlling the above conditional expression, it is possible to limit the inner and outer diameters of the first side end face of the lens barrel, such that the wall thickness of the first side end face of the lens barrel is within a reasonable range, which is beneficial to the molding of the lens barrel; at the same time, it is also possible to limit the length of the lens barrel in the direction of the optical axis within a certain range, which is beneficial to the miniaturization of the optical system. <00001

[0057] In an exemplary embodiment, the central thickness CT1 of the first lens on the optical axis, the central thickness CT2 of the second lens on the optical axis, the refractive index N1 of the first lens, and the refractive index N of the reflective polarizing element R The interval EP01 between the first side end face of the lens barrel and the first spacer along the optical axis may satisfy: 3.0 < (CT1 + CT2) × (N1 + N R ) / EP01 < 6.0. By controlling the above conditional expression, the refractive power of the first lens and the second lens can be reasonably distributed, the contribution of the aberrations of these two lenses can be controlled, and the aberrations of these two lenses can be balanced with the aberrations of other elements, ensuring that the aberrations of the optical system are at a reasonable level; at the same time, the refractive index of the reflective polarizing element can be restricted while limiting the refractive index and central thickness of the first lens within a certain range, and while ensuring the formability of the first lens, the light transmittance of the optical system can be at a reasonable level, improving the imaging clarity of the optical system; the interval between the first side end face of the lens barrel and the first spacer along the optical axis can also be restricted, improving the machinability of the lens barrel.

[0058] In an exemplary embodiment, the effective focal length f1 of the first element group and the inner diameter d1s of the first side face of the first spacer may satisfy: 1.0 < f1 / d1s < 3.0. In an example, 1.5 ≤ f1 / d1s < 2.1. By controlling the above conditional expression, the effective focal length of the first element group can be restricted within a reasonable range, and the spherical aberration generated by the first element group can be balanced with the spherical aberration generated by other element groups in the optical system, thereby ensuring that the optical system has good imaging quality; at the same time, the inner diameter of the first side face of the first spacer can also be restricted, which is beneficial to the forming of the first spacer.

[0059] In an exemplary embodiment, the opening slope angle α of the lens barrel relatively close to the first side end face may satisfy: 50.0° < α < 150.0°. In an example, 75.0° < α ≤ 125.0°. By restricting the opening slope angle of the lens barrel relatively close to the first side end face, the light passing aperture of the optical system can be restricted, ensuring that the light brightness of the optical system is within a reasonable range, and facilitating the improvement of the comfort of the user when using the optical system for a long time.

[0060] In an exemplary embodiment, the opening slope angle α of the lens barrel relatively close to the first side end face and the maximum field of view angle FOV of the optical system may satisfy: 1.0 < α / FOV < 6.0. In an example, 1.1 < α / FOV < 2.0. By controlling the above conditional expression, the opening slope angle of the lens barrel relatively close to the first side end face can be restricted, thereby constraining the light passing aperture of the optical system, ensuring that the brightness of the optical system is within a reasonable range, and improving the comfort of the user when using the optical system for a long time; at the same time, the maximum field of view angle of the optical system can also be restricted, so that the imaging range of the optical system can cover the entire photosensitive element, ensuring that the imaging circle is not seen and avoiding serious edge vignetting.

[0061] In an exemplary embodiment, the minimum inner diameter ds of the lens barrel and the total effective focal length f of the optical system may satisfy: 1.0 < ds / f < 3.0. In an example, 1.3 < ds / f < 2.0. By restricting the ratio of the minimum inner diameter of the lens barrel to the total effective focal length of the optical system, the light passing amount of the optical system can be within a reasonable range, ensuring that the imaging brightness of the optical system is within the range acceptable to the user's eyes, and improving the comfort of the user when using the optical system.

[0062] The optical system according to the above embodiment of the present application may employ multiple lenses and at least one spacer, such as the three lenses and one spacer or two spacers described above. By reasonably allocating the parameters of the lens barrel, the reflective polarizing element, the quarter-wave plate, each lens, and each spacer, the body length of the optical system can be reduced, the stray light phenomenon of the optical system can be improved, and the imaging quality of the optical system can be enhanced. The optical system configured as above has the characteristics of miniaturization, less stray light, compact structure, and good imaging quality, and can well meet the usage requirements of various portable electronic products in the projection scenario.

[0063] In an embodiment of the present application, at least one of the lens surfaces of each of the first lens to the third lens is an aspherical lens surface. The characteristics of an aspherical lens are that the curvature continuously changes from the center of the lens to the periphery of the lens. Different from a spherical lens with a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has better curvature radius characteristics and has the advantages of improving distortion aberration and improving astigmatism aberration. After using an aspherical lens, the aberration that appears during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0064] However, those skilled in the art should understand that without departing from the technical solutions claimed in the present application, the number of lenses and spacers constituting the optical system can be changed to obtain the various results and advantages described in this specification.

[0065] Specific embodiments of the optical system applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

[0066] First Implementation Method

[0067] The following is for reference Figures 2 to 5C An optical system according to a first embodiment of this application is described. Figure 2 A schematic diagram of the structure of the optical system 110 according to Embodiment 1 of the first embodiment of this application is shown; Figure 3 A schematic diagram of the structure of the optical system 120 according to Embodiment 2 of the first embodiment of this application is shown; Figure 4 A schematic diagram of the structure of an optical system 130 according to Embodiment 3 of the first embodiment of this application is shown.

[0068] like Figures 2 to 4 As shown, optical systems 110, 120, and 130 include a lens barrel P0 and a first element group, a second element group, and a third element group arranged sequentially along the optical axis from the first side to the second side within the lens barrel P0. The first element group includes a first lens E1 and a reflective polarizing element RP. The second element group includes a second lens E2 and a quarter-wave plate QWP. The third element group includes a third lens E3; in other examples, the third element group may also include a partial reflective layer BS (not shown). The optical system may also include a second isolator P2. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, reflective polarizing element RP, and quarter-wave plate QWP) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0069] The first lens E1 has two planar surfaces: the eye-side S1 and the display-side S2. The second lens E2 has positive refractive power; its eye-side S4 and display-side S5 are convex. The third lens E3 has positive refractive power; its eye-side S7 is concave and its display-side S8 is convex. The reflective polarizing element RP has two surfaces: the eye-side and the display-side S3. Its eye-side surface can be attached to the display-side S2 of the first lens E1. The quarter-wave plate QWP has two surfaces: the eye-side and the display-side S6. Its eye-side surface can be attached to the display-side S5 of the second lens E2. The partial reflective layer BS can be attached to the eye-side S7 of the third lens E3.

[0070] In this example, an image surface S9 is provided on the second side of the optical system, and a display can be mounted on the image surface S9. Image light from the display sequentially passes through the third lens E3, the quarter-wave plate QWP, and the second lens E2, and reaches the reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the second lens E2, the quarter-wave plate QWP, and reaches the partial reflective layer BS on the eye-proximity side of the third lens E3, where it undergoes a second reflection. The light after the second reflection sequentially passes through the quarter-wave plate QWP, the second lens E2, the reflective polarizing element RP, and the first lens E1, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system, after two reflections, is finally projected into the user's eye.

[0071] Table 1 shows the basic parameters of the optical system of the first embodiment, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0072]

[0073] Table 1

[0074] In this embodiment, the total effective focal length f of the optical system is 13.15 mm, the effective focal length f2 of the second element group is 54.94 mm, the effective focal length f3 of the third element group is 159.34 mm, and the Semi-FOV, half of the maximum field of view of the optical system, is 35.0°.

[0075] In the first embodiment, the near-eye side S4 and near-display side S5 of the second lens E2, and the near-eye side S7 and near-display side S8 of the third lens E3 are both aspherical. The surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0076]

[0077] 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 (i.e., 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. Table 2 gives the higher-order coefficients A4, A6, A8, A1, A2, A3, A4, A5, S7, S8 that can be used for each aspherical mirror S4, S5, S7, S8 in the first embodiment. 10 A 12 A 14 A 16 A 20 A 22 and A 24 .

[0078] Face number A4 A6 A8 A10 A12 S4 -4.5689E+00 2.1917E+00 -8.2672E-01 1.5855E-01 6.7580E-02 S5 -4.0306E-01 1.7775E-01 -1.0358E-02 -6.6249E-03 -5.2413E-03 S7 -4.7622E-01 6.2482E-03 1.9122E-03 1.2440E-03 -2.8663E-05 S8 -3.1175E-01 6.7362E-03 3.0391E-03 6.6065E-03 1.2821E-03 Face number A14 A16 A20 A22 A24 S4 -1.5456E-03 -3.6351E-02 -7.3175E-05 1.1985E-07 2.9121E-08 S5 -1.7742E-03 -1.9705E-05 -1.0928E-06 0.0000E+00 0.0000E+00 S7 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S8 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0079] Table 2

[0080] The optical systems 110, 120, and 130 in embodiments 1, 2, and 3 of the first embodiment differ in the structural dimensions of the included lens barrel P0 and the spacer. Table 3 lists some basic parameters of the lens barrel P0 and the spacer in each embodiment of the first embodiment, such as d1s, d2s, d2m, D2s, D0s, d0s, EP01, EP12, EP02, L, α, CP2, and ds. The basic parameters listed in Table 3 are... Figure 1 The annotation method shown is used for measurement, and the units of the basic parameters listed in Table 3 are all millimeters (mm).

[0081]

[0082] Table 3

[0083] Figure 5A The on-axis chromatic aberration curves of the optical systems 110, 120 and 130 of the first embodiment are shown, which represent the deflection of the focal point of light of different wavelengths after passing through the optical systems 110, 120 and 130. Figure 5B Astigmatism curves of the optical systems 110, 120, and 130 of the first embodiment are shown, representing the meridional and sagittal image plane curvatures corresponding to different field angles. Figure 5C The distortion curves of the optical systems 110, 120, and 130 of the first embodiment are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 5A to 5C It can be seen that the optical systems 110, 120 and 130 given in the first embodiment can achieve good imaging quality.

[0084] Second Implementation Method

[0085] The following is for reference Figures 6 to 9C An optical system according to a second embodiment of this application is described. Figure 6 A schematic diagram of the structure of the optical system 210 according to Embodiment 1 of the second embodiment of this application is shown; Figure 7 A schematic diagram of the structure of the optical system 220 according to Embodiment 2 of the second embodiment of this application is shown; Figure 8 A schematic diagram of the structure of an optical system 230 according to Embodiment 3 of the second embodiment of this application is shown.

[0086] like Figures 6 to 8As shown, optical systems 210, 220, and 230 include a lens barrel P0 and a first element group, a second element group, and a third element group arranged sequentially along the optical axis from the first side to the second side within the lens barrel P0. The first element group includes a first lens E1 and a reflective polarizing element RP. The second element group includes a second lens E2 and a quarter-wave plate QWP. The third element group includes a third lens E3; in other examples, the third element group may also include a partial reflective layer BS (not shown). The optical system may also include a first isolator P1 and a second isolator P2. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, reflective polarizing element RP, and quarter-wave plate QWP) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0087] The first lens E1 has positive refractive power, with its eye-side S1 being convex and its display-side S2 being planar. The second lens E2 has negative refractive power, with its eye-side S4 being concave and its display-side S5 being concave. The third lens E3 has positive refractive power, with its eye-side S7 being convex and its display-side S8 being convex. The reflective polarizing element RP has an eye-side and a display-side S3, and its eye-side can be attached to the display-side S2 of the first lens E1. The quarter-wave plate QWP has an eye-side and a display-side S6, and its eye-side can be attached to the display-side S5 of the second lens E2. The partial reflective layer BS can be attached to the display-side S8 of the third lens E3.

[0088] In this example, an image surface S9 is provided on the second side of the optical system, and a display can be mounted on the image surface S9. Image light from the display sequentially passes through a third lens E3, a quarter-wave plate QWP, a second lens E2, and reaches a reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the second lens E2, the quarter-wave plate QWP, the third lens E3, and reaches a partial reflective layer BS, where it undergoes a second reflection. The light after the second reflection sequentially passes through the third lens E3, the quarter-wave plate QWP, the second lens E2, the reflective polarizing element RP, and the first lens E1, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system, after two reflections, is finally projected into the user's eye.

[0089] Table 4 shows the basic parameters of the optical system in the second embodiment, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0090]

[0091] Table 4

[0092] In this embodiment, the total effective focal length f of the optical system is 18.40 mm, the effective focal length f1 of the first element group is 55.59 mm, the effective focal length f2 of the second element group is -102.30 mm, the effective focal length f3 of the third element group is 50.96 mm, and the Semi-FOV, half of the maximum field of view of the optical system, is 35.0°.

[0093] In the second embodiment, the near-eye side S4 and near-display side S5 of the second lens E2, and the near-eye side S7 and near-display side S8 of the third lens E3 are both aspherical. Table 5 lists the higher-order coefficients A4, A6, A8, and A6 of each aspherical mirror S4, S5, S7, and S8 that can be used in the second embodiment. 10 A 12 A 14 and A 16 .

[0094] Face number A4 A6 A8 A10 A12 A14 A16 S4 1.8698E+00 -2.2390E-01 3.0356E-02 -2.6764E-02 1.5301E-02 -2.3687E-03 0.0000E+00 S5 2.2666E+00 -2.6616E-01 2.6185E-02 -4.9176E-02 1.8551E-02 -1.3268E-03 -1.6676E-04 S7 -1.5332E+00 2.0392E-01 -1.3379E-01 -6.0260E-03 -9.5070E-04 0.0000E+00 0.0000E+00 S8 -2.1592E-01 9.6586E-02 -3.1165E-02 1.9019E-03 8.8640E-04 0.0000E+00 0.0000E+00

[0095] Table 5

[0096] The optical systems 210, 220, and 230 in embodiments 1, 2, and 3 of the second implementation differ in the structural dimensions of the included lens barrel P0 and the spacer. Table 6 lists some basic parameters of the lens barrel P0 and the spacer in each embodiment of the second implementation, such as d1s, d2s, d2m, D2s, D0s, d0s, EP01, EP12, EP02, L, α, CP2, and ds. The basic parameters listed in Table 6 are... Figure 1 The annotation method shown is used for measurement, and the units of the basic parameters listed in Table 6 are all millimeters (mm).

[0097]

[0098] Table 6

[0099] Figure 9A The on-axis chromatic aberration curves of the optical systems 210, 220 and 230 of the second embodiment are shown, which represent the deflection of the focal point of light of different wavelengths after passing through the optical systems 210, 220 and 230. Figure 9B Astigmatism curves of optical systems 210, 220, and 230 of the second embodiment are shown, representing the meridional and sagittal image plane curvatures corresponding to different field angles. Figure 9C The distortion curves of the optical systems 210, 220, and 230 of the second embodiment are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 9A to 9C It can be seen that the optical systems 210, 220 and 230 given in the second embodiment can achieve good imaging quality.

[0100] Third Implementation Method

[0101] The following is for reference Figures 10 to 13C An optical system according to a third embodiment of this application is described. Figure 10 A schematic diagram of the structure of the optical system 310 according to Embodiment 1 of the third embodiment of this application is shown; Figure 11 A schematic diagram of the structure of the optical system 320 according to Embodiment 2 of the third embodiment of this application is shown; Figure 12 A schematic diagram of the structure of an optical system 330 according to Embodiment 3 of the third embodiment of this application is shown.

[0102] like Figures 10 to 12 As shown, optical systems 310, 320, and 330 include a lens barrel P0 and a first element group, a second element group, and a third element group arranged sequentially along the optical axis from the first side to the second side within the lens barrel P0. The first element group includes a first lens E1 and a reflective polarizing element RP. The second element group includes a second lens E2 and a quarter-wave plate QWP. The third element group includes a third lens E3; in other examples, the third element group may also include a partial reflective layer BS (not shown). The optical system may also include a first isolator P1 and a second isolator P2. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, reflective polarizing element RP, and quarter-wave plate QWP) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0103] The first lens E1 has positive refractive power, with its eye-side S1 being convex and its display-side S2 being concave. The second lens E2 has negative refractive power, with its eye-side S4 being concave and its display-side S5 being convex. The third lens E3 has positive refractive power, with its eye-side S7 being convex and its display-side S8 being convex. The reflective polarizing element RP has an eye-side and a display-side S3, and its eye-side can be attached to the display-side S2 of the first lens E1. The quarter-wave plate QWP has an eye-side and a display-side S6, and its eye-side can be attached to the display-side S5 of the second lens E2. The partial reflective layer BS can be attached to the display-side S8 of the third lens E3.

[0104] In this example, an image surface S9 is provided on the second side of the optical system, and a display can be mounted on the image surface S9. Image light from the display sequentially passes through a third lens E3, a quarter-wave plate QWP, a second lens E2, and reaches a reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the second lens E2, the quarter-wave plate QWP, the third lens E3, and reaches a partial reflective layer BS, where it undergoes a second reflection. The light after the second reflection sequentially passes through the third lens E3, the quarter-wave plate QWP, the second lens E2, the reflective polarizing element RP, and the first lens E1, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system, after two reflections, is finally projected into the user's eye.

[0105] Table 7 shows the basic parameters of the optical system of the third embodiment, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0106]

[0107] Table 7

[0108] In this embodiment, the total effective focal length f of the optical system is 22.80 mm, the effective focal length f1 of the first element group is 71.59 mm, the effective focal length f2 of the second element group is -96.26 mm, the effective focal length f3 of the third element group is 52.03 mm, and the value of half of the maximum field of view (Semi-FOV) of the optical system is 35.0°.

[0109] In the third embodiment, the near-display side S2 of the first lens E1, the near-eye side S4 of the second lens E2, and the near-eye side S7 and near-display side S8 of the third lens E3 are all aspherical. Table 8 shows the higher-order coefficients A4, A6, A8, and A6 of each aspherical mirror S2, S4, S7, and S8 that can be used in the second embodiment. 10 A 12 and A 14 .

[0110] Face number A4 A6 A8 A10 A12 A14 S2 -5.3549E-01 -4.2967E-02 -5.2176E-03 6.5835E-04 3.0534E-04 0.0000E+00 S4 -3.7100E-01 -1.0986E-01 9.6748E-03 5.9110E-03 1.5600E-02 5.5160E-03 S7 -2.6410E+00 1.2461E-01 -9.3740E-03 5.1072E-02 3.0073E-03 0.0000E+00 S8 -3.0864E-01 3.9291E-02 7.4035E-03 1.7330E-02 2.8613E-03 0.0000E+00

[0111] Table 8

[0112] The optical systems 310, 320, and 330 in embodiments 1, 2, and 3 of the third embodiment differ in the structural dimensions of the included lens barrel P0 and the spacer. Table 9 lists some basic parameters of the lens barrel P0 and the spacer in each embodiment of the third embodiment, such as d1s, d2s, d2m, D2s, D0s, d0s, EP01, EP12, EP02, L, α, CP2, and ds. The basic parameters listed in Table 9 are... Figure 1 The annotation method shown is used for measurement, and the units of the basic parameters listed in Table 9 are all millimeters (mm).

[0113]

[0114] Table 9

[0115] Figure 13A The on-axis chromatic aberration curves of the optical systems 310, 320 and 330 of the third embodiment are shown, which represent the deflection of the focal point of light of different wavelengths after passing through the optical systems 310, 320 and 330. Figure 13B Astigmatism curves of optical systems 310, 320, and 330 of the third embodiment are shown, representing the meridional and sagittal image plane curvatures corresponding to different field of view angles. Figure 13C The distortion curves of the optical systems 310, 320, and 330 of the third embodiment are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 13A to 13C It can be seen that the optical systems 310, 320 and 330 given in the third embodiment can achieve good imaging quality.

[0116] In summary, Table 10 shows the values ​​of the conditional expressions for each embodiment in the first to third embodiments.

[0117] Conditional / Example 1-1 1-2 1-3 2-1 2-2 2-3 3-1 3-2 3-3 d0s / (f×tan(FOV / 2)) 2.98 2.98 2.98 2.82 2.82 2.74 2.15 2.15 2.15 <![CDATA[f2×(N2+N Q ) / EP02]]> 22.54 25.27 28.69 -26.18 -29.28 -30.38 -28.23 -32.82 -32.82 |R3-R4| / (d2s+D2s) 1.75 1.78 1.76 6.45 6.40 6.53 2.44 2.46 2.43 CT3 / (CP2+T23) 5.37 6.31 2.30 4.90 2.74 2.51 1.30 6.09 6.09 <![CDATA[(V2+V Q )×EP12 / f2]]> / / / -4.07 -3.29 -2.66 -3.41 -2.99 -2.58 <![CDATA[π×((D0s / 2) 2 -(d0s / 2) 2 ) / f 2 ]]> 4.37 3.69 3.69 2.73 2.28 2.24 1.70 1.55 1.48 (D0s-d0s) / L 0.93 0.87 0.87 0.75 0.68 0.72 0.72 0.73 0.69 f2 / d2s-f3 / d2m -3.38 -3.39 -3.11 -4.43 -4.14 -4.14 -3.91 -4.13 -4.12 <![CDATA[(CT1+CT2)×(N1+N R ) / EP01]]> / / / 4.85 5.14 5.80 3.91 4.69 5.61 f1 / d1s / / / 1.53 1.59 1.50 2.09 2.09 1.93 α / FOV 1.44 1.79 1.79 1.24 1.64 1.19 1.24 1.11 1.11 ds / f 1.87 1.92 1.92 1.82 1.82 1.80 1.38 1.42 1.42

[0118] Table 10

[0119] This application also provides an optical device, which can be a standalone projection device such as a projector, or a projection module integrated into a mobile electronic device such as VR / AR. The optical device is equipped with the optical system described above.

[0120] 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. An optical system, characterized in that, It includes a lens barrel and a first element group, a second element group, and a third element group arranged sequentially from the first side to the second side along the optical axis within the lens barrel, wherein, The first element group includes a first lens and a reflective polarizing element, wherein the reflective polarizing element is located on a second side of the first lens; The second element group includes a second lens and a quarter-wave plate, the quarter-wave plate being located on a second side of the second lens; The third element group includes a third lens, the refractive power of the third lens is positive, and the second side surface of the third lens is convex; a partial reflective layer is provided on the first side surface or the second side surface of the third lens; At least one of the first lens, the second lens, and the third lens has an aspherical surface; The first and second sides of the first lens are planes, and the refractive power of the second lens is positive; or, the refractive power of the first lens is positive, and the refractive power of the second lens is negative. The optical system has three lenses; the first side is the human eye side, and the second side is the display side. The optical system further includes a first isolator and a second isolator, wherein the first isolator is disposed on and in contact with the second side of the first lens, and the second isolator is disposed on and in contact with the second side of the second lens; Wherein, the inner diameter of the first side end face of the lens barrel is less than 45.0 mm, and the inner diameter d0s of the first side end face of the lens barrel, the total effective focal length f of the optical system and the maximum field of view FOV of the optical system satisfy: 2.15≤d0s / (f×tan(FOV / 2))<3.0; The center thickness CT3 of the third lens on the optical axis, the air gap T23 between the second element group and the third element group on the optical axis, and the maximum thickness CP2 of the second isolator satisfy: 1.30≤CT3 / (CP2+T23)≤6.31; The effective focal length f2 of the second element group, the effective focal length f3 of the third element group, the inner diameter d2s of the first side of the second isolator and the inner diameter d2m of the second side of the second isolator satisfy: -4.43≤f2 / d2s-f3 / d2m≤-3.11; The dispersion coefficient V2 of the second lens and the dispersion coefficient V of the quarter-wave plate Q The spacing EP12 between the first and second isolators along the optical axis and the effective focal length f2 of the second element group satisfy: -4.1 < (V2 + V Q )×EP12 / f2≤-2.

58.

2. The optical system according to claim 1, characterized in that, The inner diameter d0s of the first side end face of the lens barrel, the outer diameter D0s of the first side end face of the lens barrel, and the total effective focal length f of the optical system satisfy: 1.48 ≤ π × ((D0s / 2) 2 -(d0s / 2) 2 ) / f 2 ≤4.

37.

3. The optical system according to claim 1, characterized in that, The inner diameter d0s of the first side end face of the lens barrel, the outer diameter D0s of the first side end face of the lens barrel, and the length L of the lens barrel in the direction of the optical axis satisfy: 0.68≤(D0s-d0s) / L≤0.

93.

4. The optical system according to claim 1, characterized in that, The angle α of the opening slope of the lens tube relative to the first side end face satisfies: 78.0000°≤α≤125.0°.

5. The optical system according to claim 4, characterized in that, The angle α of the opening slope of the lens barrel relative to the first side end face satisfies the following condition with respect to the maximum field of view (FOV) of the optical system: 1.1 < α / FOV ≤ 1.

79.

6. The optical system according to claim 1, characterized in that, The minimum inner diameter ds of the lens barrel and the total effective focal length f of the optical system satisfy the following condition: 1.38 ≤ ds / f ≤ 1.

92.

7. The optical system according to any one of claims 1 to 6, characterized in that, The effective focal length f2 of the second element group, the refractive index N2 of the second lens, and the refractive index N of the quarter-wave plate. Q The distance EP02 between the first side end face of the lens barrel and the second spacer along the optical axis satisfies: -32.82≤f2×(N2+N Q ) / EP02≤28.

69.

8. The optical system according to any one of claims 1 to 6, characterized in that, The radius of curvature R3 of the first side surface of the second lens, the radius of curvature R4 of the second side surface of the second lens, the inner diameter d2s of the first side surface of the second isolator and the outer diameter D2s of the first side surface of the second isolator satisfy: 1.75≤|R3-R4| / (d2s+D2s)≤6.

53.

9. The optical system according to any one of claims 1 to 6, characterized in that, The center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, the refractive index N1 of the first lens, and the refractive index N of the reflective polarizing element. R The distance EP01 between the first side end face of the lens barrel and the first spacer along the optical axis satisfies: 3.91≤(CT1+CT2)×(N1+N R ) / EP01≤5.

80.

10. The optical system according to any one of claims 1 to 6, characterized in that, The effective focal length f1 of the first element group and the inner diameter d1s of the first side of the first isolator satisfy: 1.5≤f1 / d1s<2.1.

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