Optical system

Abstract

An optical system is disclosed. The optical system comprises, in order from a first side to a second side along an optical axis: a first lens having no optical power, a first side of which is a plane and a second side of which is a plane; a reflective polarizing element; a quarter-wave plate; and a second lens having positive optical power, a first side of which is a convex surface. The optical system satisfies: 5.3 < f / EPD < 6.5 and 0.4 < f2 / (T2a1+T2b1+T2c1+T2d1) < 1.2, where EPD is an entrance pupil diameter of the optical system, f is a total effective focal length of the optical system, f2 is an effective focal length of the second lens, T2a1 is a first effective half aperture of the first side of the second lens in a first direction, T2c1 is a second effective half aperture of the first side of the second lens in the first direction, T2b1 is a third effective half aperture of the first side of the second lens in a second direction perpendicular to the first direction, and T2d1 is a fourth effective half aperture of the first side of the second lens in the second direction.

Description

Technical Field

[0001] This application relates to the field of optical components, and more specifically, to an optical system. Background Technology

[0002] With the continuous advancement of science and technology and the ongoing development of society, virtual reality (VR) technology has experienced rapid growth in recent years due to its advantages, such as the ability to combine virtual and real elements, and has been widely applied in various fields. For example, training systems have been established using virtual technology in aviation, satellite, and education. As the economy develops, users' demand for entertainment is increasing. Electronic products equipped with optical systems, with their advantages such as virtual reality technology, are gaining popularity among users, and their industrial ecosystem is flourishing.

[0003] Currently, most mainstream optical systems employ a folding optical architecture, which includes multiple lenses and reflective polarizing elements and quarter-wave plates attached to the lenses, with the reflective polarizing elements and quarter-wave plates playing crucial roles. However, if the lens is curved, it increases the difficulty of the coating process, leading to a decrease in coating quality; if the lens is planar, it reduces system variables, limits the space for system performance optimization, and reduces the external field of view performance. Summary of the Invention

[0004] This application provides an optical system comprising, along the optical axis from a first side to a second side: a first lens without optical power, having a first side planar and a second side planar; a reflective polarizing element; a quarter-wave plate; and a second lens with positive optical power, having a first side planar convex. The optical system satisfies: 5.3 < f / EPD < 6.5 and 0.4 < f2 / (T2a1+T2b1+T2c1+T2d1) < 1.2, where EPD is the entrance pupil diameter of the optical system, f is the total effective focal length of the optical system, f2 is the effective focal length of the second lens, T2a1 is the first effective half-aperture of the first side planar surface of the second lens in a first direction, T2c1 is the second effective half-aperture of the first side planar surface of the second lens in a first direction, T2b1 is the third effective half-aperture of the first side planar surface of the second lens in a second direction perpendicular to the first direction, and T2d1 is the fourth effective half-aperture of the first side planar surface of the second lens in a second direction.

[0005] In one embodiment, at least one of the first and second side surfaces of the second lens is an aspherical mirror.

[0006] In one embodiment, the optical system may satisfy: 0.9 < R3 / (T2a1+T2c1) < 3, where R3 is the radius of curvature of the first side surface of the second lens, T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction, and T2c1 is the second effective half-aperture of the first side surface of the second lens in the first direction.

[0007] In one embodiment, the optical system may satisfy: 0.8 < (T2b1 + T2d1) / (T2b2 + T2d2) < 1.2, where T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction.

[0008] In one embodiment, the optical system may satisfy: 0.6 < (CT1 + CTR + CTQ + T12) / CT2 < 1.8, where 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, T12 is the distance from the quarter-wave plate to the first side of the second lens on the optical axis, and CT2 is the center thickness of the second lens on the optical axis.

[0009] In one embodiment, the optical system may satisfy: 0.9 < |R4| / (T2a2+T2b2+T2c2+T2d2) < 2.9, where R4 is the radius of curvature of the second side surface of the second lens, T2a2 is the first effective half-aperture of the second side surface of the second lens in the first direction, T2c2 is the second effective half-aperture of the second side surface of the second lens in the first direction, T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction.

[0010] In one embodiment, the optical system may satisfy: 0.1 < |R3 / R4|×(T2a1 / T2a2) < 1.3, where R3 is the radius of curvature of the first side surface of the second lens, R4 is the radius of curvature of the second side surface of the second lens, T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction, and T2a2 is the first effective half-aperture of the second side surface of the second lens in the first direction.

[0011] In one embodiment, the optical system may satisfy: 1.0 < f / T2a1 < 1.6, where f is the total effective focal length of the optical system and T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction.

[0012] In one embodiment, the optical system may satisfy: 1.9 < (T2b2 + T2d2) / f < 2.4, where f is the total effective focal length of the optical system, T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction.

[0013] In one embodiment, the optical system may satisfy: 0.4 < CT2 / (T2c2-T2a2) < 2.6, where CT2 is the center thickness of the second lens on the optical axis, T2a2 is the first effective half-aperture of the second side surface of the second lens in the first direction, and T2c2 is the second effective half-aperture of the second side surface of the second lens in the first direction.

[0014] In one embodiment, the optical system may satisfy: 2.9 < (T2b2 + T2d2) / TD < 4.4, where T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction, T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction, and TD is the distance on the optical axis from the first side surface of the first lens to the second side surface of the second lens.

[0015] In one embodiment, the optical system may satisfy: 1.0 < N2 × (T2a1 / T2b1) < 1.7, where T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction, T2b1 is the third effective half-aperture of the first side surface of the second lens in the second direction, and N2 is the refractive index of the second lens.

[0016] In one embodiment, the optical system may satisfy: 0.7 < f2 / (T2c2+T2d2) < 2.1, where T2c2 is the second effective half-aperture of the second side surface of the second lens in the first direction, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction.

[0017] This application provides an optical system comprising, along an optical axis from a first side to a second side: a first lens without optical power, having a first side planar and a second side planar; a reflective polarizing element; a quarter-wave plate; and a second lens with positive optical power, having a first side planar convex. The optical system satisfies: 5.3 < f / EPD < 6.5 and 0.9 < |R4| / (T2a2+T2b2+T2c2+T2d2) < 2.9, where EPD is the entrance pupil diameter of the optical system, f is the total effective focal length of the optical system, R4 is the radius of curvature of the second side planar surface of the second lens, T2a2 is the first effective half-aperture of the second side planar surface of the second lens in a first direction, T2c2 is the second effective half-aperture of the second side planar surface of the second lens in a first direction, T2b2 is the third effective half-aperture of the second side planar surface of the second lens in a second direction perpendicular to the first direction, and T2d2 is the fourth effective half-aperture of the second side planar surface of the second lens in a second direction.

[0018] In one embodiment, the optical system may satisfy: 0.9 < R3 / (T2a1+T2c1) < 3, where R3 is the radius of curvature of the first side surface of the second lens, T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction, and T2c1 is the second effective half-aperture of the first side surface of the second lens in the first direction.

[0019] In one embodiment, the optical system may satisfy: 0.8 < (T2b1 + T2d1) / (T2b2 + T2d2) < 1.2, where T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction.

[0020] In one embodiment, the optical system may satisfy: 0.6 < (CT1 + CTR + CTQ + T12) / CT2 < 1.8, where 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, T12 is the distance from the quarter-wave plate to the first side of the second lens on the optical axis, and CT2 is the center thickness of the second lens on the optical axis.

[0021] In one embodiment, the optical system may satisfy: 0.1 < |R3 / R4|×(T2a1 / T2a2) < 1.3, where R3 is the radius of curvature of the first side surface of the second lens, R4 is the radius of curvature of the second side surface of the second lens, T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction, and T2a2 is the first effective half-aperture of the second side surface of the second lens in the first direction.

[0022] In one embodiment, the optical system may satisfy: 1.0 < f / T2a1 < 1.6, where f is the total effective focal length of the optical system and T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction.

[0023] In one embodiment, the optical system may satisfy: 1.9 < (T2b2 + T2d2) / f < 2.4, where f is the total effective focal length of the optical system, T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction.

[0024] In one embodiment, the optical system may satisfy: 0.4 < CT2 / (T2c2-T2a2) < 2.6, where CT2 is the center thickness of the second lens on the optical axis, T2a2 is the first effective half-aperture of the second side surface of the second lens in the first direction, and T2c2 is the second effective half-aperture of the second side surface of the second lens in the first direction.

[0025] In one embodiment, the optical system may satisfy: 2.9 < (T2b2 + T2d2) / TD < 4.4, where T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction, T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction, and TD is the distance on the optical axis from the first side surface of the first lens to the second side surface of the second lens.

[0026] In one embodiment, the optical system may satisfy: 1.0 < N2 × (T2a1 / T2b1) < 1.7, where T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction, T2b1 is the third effective half-aperture of the first side surface of the second lens in the second direction, and N2 is the refractive index of the second lens.

[0027] In one embodiment, the optical system may satisfy: 0.7 < f2 / (T2c2+T2d2) < 2.1, where T2c2 is the second effective half-aperture of the second side surface of the second lens in the first direction, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction.

[0028] In one embodiment, the optical system may satisfy: 0.4 < f2 / (T2a1+T2b1+T2c1+T2d1) < 1.2, where f2 is the effective focal length of the second lens, T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction, T2c1 is the second effective half-aperture of the first side surface of the second lens in the first direction, T2b1 is the third effective half-aperture of the first side surface of the second lens in the second direction, and T2d1 is the fourth effective half-aperture of the first side surface of the second lens in the second direction.

[0029] In one exemplary embodiment of this application, the optical system may include a first lens, a reflective polarizing element, a quarter-wave plate, and a second lens. The reflective polarizing element and the quarter-wave plate can be combined and attached to the second side of the first lens, which does not have optical power. This allows the reflective polarizing element and the quarter-wave plate to be attached to a flat surface, thereby reducing the difficulty of the film application process and improving the film application quality. This application, by reasonably combining planar lenses (such as the first lens, whose first and second sides are planar) and curved lenses (such as the second lens, whose first side is curved), not only reduces the difficulty of the film application process but also improves the external field of view performance. Based on this, by setting the optical system to satisfy 5.3 < f / EPD < 6.5 and 0.4 < f2 / (T2a1+T2b1+T2c1+T2d1) < 1.2, it is possible to control the aperture value Fno (i.e., f / EPD) of the optical system within a certain range. By controlling the ratio of the effective focal length of the second lens to the sum of the four effective half-apertures in two directions on its first side, it is beneficial to ensure that the second lens has positive optical power, thus enabling it to converge light and achieve a large field of view. At the same time, it is also beneficial to control the thickness of the second lens within a reasonable range, which is conducive to the shaping of the second lens. Furthermore, it is beneficial to form a non-circular structure on the first side of the second lens. The position from the center of the optical area on the first side of the second lens to the edge of the effective aperture contour corresponds to the nose side of the user experiencing the optical system, thus making the design of the optical system more ergonomic and improving the user's experience and comfort.

[0030] In another exemplary embodiment of this application, the optical system may include a first lens, a reflective polarizing element, a quarter-wave plate, and a second lens. The reflective polarizing element and the quarter-wave plate can be combined and attached to the second side of the first lens, which does not have optical power. This allows the reflective polarizing element and the quarter-wave plate to be attached to a flat surface, thereby reducing the difficulty of the film application process and improving the film application quality. This application, by reasonably combining planar lenses (such as the first lens, whose first and second sides are planar) and curved lenses (such as the second lens, whose first side is curved), not only reduces the difficulty of the film application process but also improves the external field of view performance. Based on this, by setting the optical system to satisfy 5.3 < f / EPD < 6.5 and 0.9 < |R4| / (T2a2+T2b2+T2c2+T2d2) < 2.9, it is possible to control the aperture value Fno (i.e., f / EPD) of the optical system within a certain range. By controlling the ratio of the radius of curvature of the second side of the second lens to the sum of the four effective half-apertures in two directions of the second side, it is beneficial to rationally set the shape of the second side of the second lens and to the formation of the second lens. On the other hand, it is beneficial to form a non-circular structure of the second side of the second lens. The position from the center of the optical area of ​​the second side of the second lens to the edge of the effective aperture contour corresponds to the nose side of the user experiencing the optical system. This makes the design of the optical system more ergonomic and improves the user's experience and comfort. Attached Figure Description

[0031] 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:

[0032] Figure 1 These are schematic diagrams of the optical systems of Examples 1 to 3;

[0033] Figures 2A to 2C The on-axis chromatic aberration curves, astigmatism curves, and distortion curves of the optical systems of Examples 1 to 3 are shown respectively.

[0034] Figure 3 These are schematic diagrams of the optical systems in Examples 4 to 6;

[0035] Figures 4A to 4C The on-axis chromatic aberration curves, astigmatism curves, and distortion curves of the optical systems of Examples 4 to 6 are shown respectively.

[0036] Figure 5 These are schematic diagrams of the optical systems in Examples 7 to 9;

[0037] Figures 6A to 6CThe on-axis chromatic aberration curves, astigmatism curves, and distortion curves of the optical systems of Examples 7 to 9 are shown respectively.

[0038] Figure 7 This is a schematic diagram of parameters T2a1, T2b1, T2c1, and T2d1 of the first side surface of the second lens according to an embodiment of this application; and

[0039] Figure 8 This is a schematic diagram of the parameters T2a2, T2b2, T2c2 and T2d2 of the second side surface of the second lens according to an embodiment of this application. Detailed Implementation

[0040] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0041] 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.

[0042] Furthermore, in this specification, the orientations or positional relationships indicated by terms such as up, down, left, and right are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the purpose of facilitating the description of this application and simplifying the description, and do not imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0043] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0044] In this text, 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 first side refers to, for example, the side closer to the user's eye, and the second side refers to, for example, the side closer to the display screen, where the display screen may have an image source surface (i.e., an image surface). The surface of each lens closest to the first side is called the first side surface of the lens, and the surface of each lens closest to the second side is called the second side surface of the lens.

[0045] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0046] 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.

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other. The following embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this application. It should be pointed out that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] The features, principles and other aspects of this application are described in detail below.

[0049] An optical system according to an exemplary embodiment of this application may include a lens without optical power, such as a first lens, and a lens with optical power, such as a second lens. The first side surface of the first lens may be planar, and the second side surface may be planar; the first side surface of the second lens may be convex.

[0050] According to an exemplary embodiment of this application, both the first lens and the second lens may have an optical region for optical imaging and a non-optical region extending outward from the outer periphery of the optical region. Generally speaking, the optical region refers to the area of ​​the lens used for optical projection, while the non-optical region is the structural area of ​​the lens. During the projection process of the optical system, the optical regions of each lens can transmit light from the image surface to form an optical path, which is then projected out; while the non-optical regions of each assembled lens are housed in a lens barrel that cannot transmit light, thus the non-optical regions do not directly participate in the projection process of the optical system. It should be noted that, for ease of description, this application describes each lens as having both an optical region and a non-optical region, but it should be understood that the optical region and the non-optical region of the lens can be formed as a whole during the manufacturing process, rather than as two separate parts.

[0051] In an exemplary implementation, such as Figure 1 As shown, the optical system according to this application further includes a reflective polarizing element RP and a quarter-wave plate QWP located on the second side of the first lens E1. The reflective polarizing element RP can be attached to the second side of the first lens E1. The quarter-wave plate QWP can be attached to the surface of the reflective polarizing element RP. In other words, the first side of the reflective polarizing element RP can be attached to the second side of the first lens E1. The first side of the quarter-wave plate QWP can be attached to the second side of the reflective polarizing element RP.

[0052] In an exemplary implementation, such as Figure 1 As shown, the optical system according to this application also includes an aperture stop STO disposed on the first side and an image surface IMG disposed on the second side. The user's eye can view the image projected by the image surface IMG at the position of the aperture stop STO. That is, the image light on the image surface IMG is finally projected to the user's eye after multiple refractions and reflections through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, and the first lens E1.

[0053] In an exemplary implementation, such as Figure 1 As shown, the optical system according to this application also includes a partial reflective element BS attached to a second side surface of the second lens E2. The partial reflective element BS can be configured to allow a portion of the light to pass through while the other portion is reflected.

[0054] This application, by reasonably setting up a reflective polarizing element RP, a quarter-wave plate QWP, a partial reflective element BS, and multiple lenses such as the first lens E1 and the second lens E2, can compress the length of the lens group required for system projection without affecting the projection quality by utilizing light reflection and / or refraction.

[0055] According to exemplary embodiments of this application, such as Figure 1 As shown, the image light emitted by the light source exits from the image surface IMG on the second side, passes through 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 quarter-wave plate QWP and reaches the partial reflective element BS on the second side of the second lens E2, where it undergoes a second reflection. The light after the second reflection passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, and the first lens E1, and is finally projected onto the aperture STO (i.e., the position where the user's eye views the image).

[0056] In an exemplary implementation, such as Figure 7 As shown, T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction X. In other words, T2a1 is the distance from the center of the optical region of the first side surface of the second lens to the upper edge of the effective aperture profile of the first side surface of the second lens.

[0057] T2c1 is the second effective half-aperture of the first side surface of the second lens in the first direction X. In other words, T2c1 is the distance from the center of the optical region of the first side surface of the second lens to the lower edge of the effective aperture profile of the first side surface of the second lens.

[0058] T2b1 is the third effective half-aperture of the first side surface of the second lens in the second direction Y, which is perpendicular to the first direction X. In other words, T2b1 is the distance from the center of the optical region of the first side surface of the second lens to the left edge of the effective aperture profile of the first side surface of the second lens.

[0059] T2d1 is the fourth effective half-aperture of the first side surface of the second lens in the second direction Y. In other words, T2d1 is the distance from the center of the optical region of the first side surface of the second lens to the right edge of the effective aperture profile of the first side surface of the second lens.

[0060] In an exemplary implementation, such as Figure 8 As shown, T2a2 is the first effective half-aperture of the second side surface of the second lens in the first direction X. In other words, T2a2 is the distance from the center of the optical region of the second side surface of the second lens to the upper edge of the effective aperture profile of the second side surface of the second lens.

[0061] T2c2 is the second effective half-aperture of the second side surface of the second lens in the first direction X. In other words, T2c2 is the distance from the center of the optical region of the second side surface of the second lens to the lower edge of the effective aperture profile of the second side surface of the second lens.

[0062] T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction Y. In other words, T2b2 is the distance from the center of the optical region of the second side surface of the second lens to the left edge of the effective aperture profile of the second side surface of the second lens.

[0063] T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction Y. In other words, T2d2 is the distance from the center of the optical region of the second side surface of the second lens to the right edge of the effective aperture profile of the second side surface of the second lens.

[0064] In one exemplary embodiment, the optical system according to this application satisfies: 5.3 < f / EPD < 6.5 and 0.4 < f2 / (T2a1+T2b1+T2c1+T2d1) < 1.2, where EPD is the entrance pupil diameter of the optical system, f is the total effective focal length of the optical system, f2 is the effective focal length of the second lens, T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction X, T2c1 is the second effective half-aperture of the first side surface of the second lens in the first direction X, T2b1 is the third effective half-aperture of the first side surface of the second lens in the second direction Y perpendicular to the first direction X, and T2d1 is the fourth effective half-aperture of the first side surface of the second lens in the second direction Y.

[0065] The optical system provided in this application may include a first lens, a reflective polarizing element, a quarter-wave plate, and a second lens. The reflective polarizing element and the quarter-wave plate can be combined and attached to the second side of the first lens, which does not have optical power. This allows the reflective polarizing element and the quarter-wave plate to be attached to a flat surface, thereby reducing the difficulty of the coating process and improving the coating quality. By reasonably combining planar lenses (such as the first lens, whose first and second sides are planar) and curved lenses (such as the second lens, whose first side is curved), this application not only reduces the coating process but also improves the external field of view performance. Based on this, by setting the optical system to satisfy 5.3 < f / EPD < 6.5 and 0.4 < f2 / (T2a1+T2b1+T2c1+T2d1) < 1.2, it is possible to control the aperture value Fno (i.e., f / EPD) of the optical system within a certain range. By controlling the ratio of the effective focal length of the second lens to the sum of the four effective half-apertures in two directions on its first side, it is beneficial to ensure that the second lens has positive optical power, thus enabling it to converge light and achieve a large field of view. At the same time, it is also beneficial to control the thickness of the second lens within a reasonable range, which is conducive to the shaping of the second lens. Furthermore, it is beneficial to form a non-circular structure on the first side of the second lens. The position from the center of the optical area on the first side of the second lens to the edge of the effective aperture contour corresponds to the nose side of the user experiencing the optical system, thus making the design of the optical system more ergonomic and improving the user's experience and comfort.

[0066] In another exemplary embodiment, the optical system according to this application may satisfy: 5.3 < f / EPD < 6.5 and 0.9 < |R4| / (T2a2+T2b2+T2c2+T2d2) < 2.9, where EPD is the entrance pupil diameter of the optical system, f is the total effective focal length of the optical system, R4 is the radius of curvature of the second side surface of the second lens, T2a2 is the first effective half-aperture of the second side surface of the second lens in the first direction X, T2c2 is the second effective half-aperture of the second side surface of the second lens in the first direction X, T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction Y perpendicular to the first direction X, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction Y.

[0067] The optical system provided in this application may include a first lens, a reflective polarizing element, a quarter-wave plate, and a second lens. The reflective polarizing element and the quarter-wave plate can be combined and attached to the second side of the first lens, which does not have optical power. This allows the reflective polarizing element and the quarter-wave plate to be attached to a flat surface, thereby reducing the difficulty of the coating process and improving the coating quality. By reasonably combining planar lenses (such as the first lens, whose first and second sides are planar) and curved lenses (such as the second lens, whose first side is curved), this application not only reduces the coating process but also improves the external field of view performance. Based on this, by setting the optical system to satisfy 5.3 < f / EPD < 6.5 and 0.9 < |R4| / (T2a2+T2b2+T2c2+T2d2) < 2.9, it is possible to control the aperture value Fno (i.e., f / EPD) of the optical system within a certain range. By controlling the ratio of the radius of curvature of the second side of the second lens to the sum of the four effective half-apertures in two directions of the second side, it is beneficial to rationally set the shape of the second side of the second lens and to the formation of the second lens. On the other hand, it is beneficial to form a non-circular structure of the second side of the second lens. The position from the center of the optical area of ​​the second side of the second lens to the edge of the effective aperture contour corresponds to the nose side of the user experiencing the optical system. This makes the design of the optical system more ergonomic and improves the user's experience and comfort.

[0068] In an exemplary embodiment, the optical system according to this application satisfies: 0.9 < R3 / (T2a1+T2c1) < 3, where R3 is the radius of curvature of the first side surface of the second lens, T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction X, and T2c1 is the second effective half-aperture of the first side surface of the second lens in the first direction X. Satisfying 0.9 < R3 / (T2a1+T2c1) < 3 is beneficial for controlling the shape of the second lens, for shaping the second lens, and for improving the user's immersive experience.

[0069] In an exemplary embodiment, the optical system according to this application satisfies: 0.8 < (T2b1 + T2d1) / (T2b2 + T2d2) < 1.2, where T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction Y, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction Y. Satisfying 0.8 < (T2b1 + T2d1) / (T2b2 + T2d2) < 1.2 allows the second lens to form a chamfered edge effect by controlling the ratio of the distances from the center of the optical regions of the first and second side surfaces of the second lens to the left and right contours of the effective aperture edge. This facilitates control over the shape of the light path of the light-emitting screen, and contributes to the miniaturization of the optical system and improved user comfort.

[0070] In an exemplary embodiment, the optical system according to this application satisfies: 0.6 < (CT1 + CTR + CTQ + T12) / CT2 < 1.8, where 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, T12 is the distance from the quarter-wave plate to the first side of the second lens on the optical axis, and CT2 is the center thickness of the second lens on the optical axis. Satisfying 0.6 < (CT1 + CTR + CTQ + T12) / CT2 < 1.8 allows for a larger air gap between the quarter-wave plate and the second lens on the optical axis by controlling the relationship between CT1, CTR, CTQ, T12, and CT2. This helps to reduce the incident angle of light on the quarter-wave plate, thereby reducing the angular effect of the quarter-wave plate.

[0071] In an exemplary embodiment, the optical system according to this application satisfies: 0.1 < |R3 / R4|×(T2a1 / T2a2) < 1.3, where R3 is the radius of curvature of the first side surface of the second lens, R4 is the radius of curvature of the second side surface of the second lens, T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction X, and T2a2 is the first effective half-aperture of the second side surface of the second lens in the first direction X. Satisfying 0.1 < |R3 / R4|×(T2a1 / T2a2) < 1.3 is beneficial for setting the second lens to have positive optical power, which is beneficial for increasing the field of view of the system. At the same time, it is beneficial for controlling the light-gathering effect of the first side surface of the second lens, which is beneficial for improving the user's immersive experience.

[0072] In an exemplary embodiment, the optical system according to this application satisfies: 1.0 < f / T2a1 < 1.6, where f is the total effective focal length of the optical system, and T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction X. Satisfying 1.0 < f / T2a1 < 1.6 allows for the increase of immersion and field of view of the optical system by controlling the ratio of the total effective focal length of the optical system to the effective half-aperture from the center of the optical region on the first side surface of the second lens to the upper edge of the effective diameter, thereby enhancing the virtual-real interaction of the device equipped with the optical system.

[0073] In an exemplary embodiment, the optical system according to this application satisfies: 1.9 < (T2b2 + T2d2) / f < 2.4, where f is the total effective focal length of the optical system, T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction Y, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction Y. Satisfying 1.9 < (T2b2 + T2d2) / f < 2.4 allows the system to have suitable optical power by controlling the ratio of the sum of the effective half-apertures from the center of the optical region of the second side surface of the second lens to the left and right edges of the effective aperture to the total effective focal length of the optical system. This also facilitates control of the lens size in the left and right directions of the second lens, improves the shaping of the second lens, controls the light aperture in the left and right directions, increases the field of view of the system, and enhances the user's immersive experience.

[0074] In an exemplary embodiment, the optical system according to this application satisfies: 0.4 < CT2 / (T2c2-T2a2) < 2.6, where CT2 is the center thickness of the second lens on the optical axis, T2a2 is the first effective half-aperture of the second side surface of the second lens in the first direction X, and T2c2 is the second effective half-aperture of the second side surface of the second lens in the first direction X. Satisfying 0.4 < CT2 / (T2c2-T2a2) < 2.6 allows for a larger thickness of the second lens by controlling the ratio of the center thickness of the second lens on the optical axis to the difference between the effective half-aperture at the center of the optical region of the second side surface of the second lens and the effective half-aperture at the lower and upper edges. This facilitates increasing the diameter and wall thickness of the lens, making it easier to shape. It also helps to form a near-elliptical chamfer on the second side surface of the second lens in the vertical direction (i.e., the first direction), making the device equipped with this optical system suitable for the user's face shape.

[0075] In an exemplary embodiment, the optical system according to this application satisfies: 2.9 < (T2b2 + T2d2) / TD < 4.4, where T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction Y, T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction Y, and TD is the distance on the optical axis from the first side surface of the first lens to the second side surface of the second lens. Satisfying 2.9 < (T2b2 + T2d2) / TD < 4.4 allows for the control of the ratio of the sum of the effective half-apertures from the center of the optical region of the second side surface of the second lens to the left and right edges of the effective aperture to the distance on the optical axis from the first side surface of the first lens to the second side surface of the second lens. This benefits both the effective focal length of the second lens and its shaping, and the optical power of the optical system, enabling thinner devices equipped with the optical system and facilitating miniaturization.

[0076] In an exemplary embodiment, the optical system according to this application satisfies: 1.0 < N2 × (T2a1 / T2b1) < 1.7, where T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction X, T2b1 is the third effective half-aperture of the first side surface of the second lens in the second direction Y, and N2 is the refractive index of the second lens. Satisfying 1.0 < N2 × (T2a1 / T2b1) < 1.7 is beneficial for controlling the optical power of the second lens, controlling the principal ray angle of the optical system, and meeting the chip CRA requirements. Furthermore, it is beneficial for controlling the edge thickness of the second lens and for shaping the second lens.

[0077] In an exemplary embodiment, the optical system according to this application satisfies: 0.7 < f2 / (T2c2+T2d2) < 2.1, where T2c2 is the second effective half-aperture of the second side surface of the second lens in the first direction X, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction Y. Satisfying 0.7 < f2 / (T2c2+T2d2) < 2.1 is beneficial for controlling the optical power of the second lens, reducing the incident angle of light on the quarter-wave plate, thereby reducing the angular effect of the quarter-wave plate, and also for controlling the edge thickness of the second lens, which is beneficial for the shaping of the second lens.

[0078] In an exemplary embodiment, the optical system according to this application further includes an aperture stop disposed between the first side and the first lens. Optionally, the optical system may also include a filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface. This application proposes an optical system with characteristics such as low coating process, miniaturization, excellent external field of view, good user experience, good comfort, and high image quality. The optical system according to the above embodiments of this application can employ a first lens, a reflective polarizing element, a quarter-wave plate, and a second lens. By reasonably matching the components, the incident light can be effectively converged, the overall optical length of the optical system can be reduced, and the manufacturability of the optical system can be improved, making the optical system more conducive to production and processing.

[0079] In embodiments of this application, at least one of the mirror surfaces of the second lens is an aspherical mirror surface; that is, at least one of the first and second side surfaces of the second lens is an aspherical mirror surface. An aspherical lens is characterized by a continuously changing curvature from the lens center to the lens periphery. Unlike a spherical lens, which has a constant curvature from the lens center to the lens periphery, an aspherical lens has better radius of curvature characteristics, offering advantages in improving distortion aberrations and astigmatism. By using an aspherical lens, aberrations occurring during imaging can be eliminated as much as possible, thereby improving image quality. Optionally, both the first and second side surfaces of the second lens are aspherical mirror surfaces.

[0080] However, those skilled in the art will understand that the number of lenses constituting the optical system can be varied to obtain the various results and advantages described herein without departing from the technical solutions claimed in this application. For example, although two lenses are described as an example in the embodiments, the optical system is not limited to including two lenses. If desired, the optical system may also include other numbers of lenses.

[0081] Specific embodiments of the optical system applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

[0082] Example 1

[0083] The following is for reference Figure 1 The optical system according to Embodiment 1 of this application is described. Figure 1 The optical system of Embodiment 1 is shown.

[0084] like Figure 1 As shown, the optical system includes, from the first side to the second side, the following components in sequence: aperture STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG.

[0085] The first lens E1 has no optical power; its first side surface is flat, and its second side surface is flat. The second lens E2 has positive optical power; its first side surface is convex, and its second side surface is convex. A reflective polarizing element RP is attached to the second side surface of the first lens E1. A quarter-wave plate QWP is attached to the second side surface of the reflective polarizing element RP. A partial reflective element BS is attached to the second side surface of the second lens E2.

[0086] In this example, a light source can be positioned on the image plane IMG. Image light from the image plane IMG passes through the second lens E2 and reaches the reflective polarizer RP, where it undergoes a first reflection. The light after the first reflection passes through the quarter-wave plate QWP and reaches the partial reflective element BS on the second side of the second lens E2, where it undergoes a second reflection. The light after the second reflection passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizer RP, and the first lens E1, and is finally projected onto a target object (not shown) in space. For example, when this optical system is mounted on an electronic device such as VR, the light after the two reflections is finally projected into the eyes of the user.

[0087] Table 1 shows the basic parameters of the optical system of Embodiment 1, where the units for radius of curvature and thickness / distance are millimeters (mm). Image light from the image plane IMG passes through each component in the order of number 14 to number 1 and is finally projected onto the target object in space, such as the human eye.

[0088]

[0089] Table 1

[0090] In this example, the effective focal length f2 of the second lens is 120.58 mm, the total effective focal length f of the optical system is 29.19 mm, the entrance pupil diameter EPD of the optical system is 4.50 mm, the distance TD between the first side surface of the first lens and the second side surface of the second lens on the optical axis is 18.81 mm, the center thickness CTR of the reflective polarizing element on the optical axis is 0.09 mm, and the center thickness CTQ of the quarter-wave plate on the optical axis is 0.09 mm.

[0091] Table 2 shows the basic parameters of the second lens in the optical system of Embodiment 1, where the unit of each parameter is millimeters (mm).

[0092] parameter T2a1 T2b1 T2c1 T2d1 T2a2 T2b2 T2c2 T2d2 numerical values 19.14 27.93 31.38 27.93 19.35 28.23 31.72 28.23

[0093] Table 2

[0094] In Embodiment 1, both the first and second side surfaces of the second lens E2 are aspherical. The surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0095]

[0096] 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 3 below gives the higher-order coefficients A4, A6, A8, A1, A2, A3, A4, A5, A6, A8, A9, A1 ... 10 A 12 A 14 A 16 A 18 and A 20 .

[0097] The first side of the second lens The second side of the second lens A4 -5.0225E-01 7.1837E-07 A6 -5.5835E-02 -1.1483E-09 A8 9.8596E-02 2.8740E-13 A10 -2.1046E-02 4.2053E-16 A12 1.3974E-03 -1.5054E-19 A14 8.0498E-04 0.0000E+00 A16 0.0000E+00 0.0000E+00 A18 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00

[0098] Table 3

[0099] Example 2

[0100] The following is for reference Figure 1 An optical system according to Embodiment 2 of this application is described. In this embodiment and the following embodiments, for the sake of brevity, descriptions similar to those in Embodiment 1 will be omitted. Figure 1 The optical system of Embodiment 2 is shown.

[0101] like Figure 1 As shown, the optical system includes, from the first side to the second side, the following components in sequence: aperture STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG.

[0102] The first lens E1 has no optical power; its first side surface is flat, and its second side surface is flat. The second lens E2 has positive optical power; its first side surface is convex, and its second side surface is convex. A reflective polarizing element RP is attached to the second side surface of the first lens E1. A quarter-wave plate QWP is attached to the second side surface of the reflective polarizing element RP. A partial reflective element BS is attached to the second side surface of the second lens E2.

[0103] In this example, a light source can be positioned on the image plane IMG. Image light from the image plane IMG passes through the second lens E2 and reaches the reflective polarizer RP, where it undergoes a first reflection. The light after the first reflection passes through the quarter-wave plate QWP and reaches the partial reflective element BS on the second side of the second lens E2, where it undergoes a second reflection. The light after the second reflection passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizer RP, and the first lens E1, and is finally projected onto a target object (not shown) in space. For example, when this optical system is mounted on an electronic device such as VR, the light after the two reflections is finally projected into the eyes of the user.

[0104] In this example, the structure and parameters of the aperture stop STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG are the same as those in Embodiment 1. Therefore, the basic parameter table of the optical system in this example is exactly the same as the basic parameters shown in Table 1 of Embodiment 1. To avoid redundancy, this example will not describe it in detail; please refer to the relevant content disclosed in Embodiment 1 for details.

[0105] In this example, both the first and second side surfaces of the second lens E2 are aspherical. The higher-order coefficients of each aspherical mirror surface may be the same as those shown in Table 3 of Embodiment 1. Therefore, to avoid redundancy, this example will not describe the higher-order coefficients of each aspherical mirror surface in detail; please refer to the relevant content disclosed in Embodiment 1 for details.

[0106] In this example, the values ​​of the optical technical parameters f2, f, EPD, TD, CTR, and CTQ can be the same as those in Example 1. Therefore, to avoid redundancy, this example will not describe the values ​​of these parameters in detail; please refer to the relevant content disclosed in Example 1 for details.

[0107] Table 4 shows the basic parameters of the second lens in the optical system of Example 2, where the unit of each parameter is millimeters (mm).

[0108] parameter T2a1 T2b1 T2c1 T2d1 T2a2 T2b2 T2c2 T2d2 numerical values 22.28 30.75 31.38 30.75 22.52 31.09 31.72 31.09

[0109] Table 4

[0110] Example 3

[0111] The following is for reference Figure 1 The optical system according to Embodiment 3 of this application is described. Figure 1 The optical system of Embodiment 3 is shown.

[0112] like Figure 1 As shown, the optical system includes, from the first side to the second side, the following components in sequence: aperture STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG.

[0113] The first lens E1 has no optical power; its first side surface is flat, and its second side surface is flat. The second lens E2 has positive optical power; its first side surface is convex, and its second side surface is convex. A reflective polarizing element RP is attached to the second side surface of the first lens E1. A quarter-wave plate QWP is attached to the second side surface of the reflective polarizing element RP. A partial reflective element BS is attached to the second side surface of the second lens E2.

[0114] In this example, a light source can be positioned on the image plane IMG. Image light from the image plane IMG passes through the second lens E2 and reaches the reflective polarizer RP, where it undergoes a first reflection. The light after the first reflection passes through the quarter-wave plate QWP and reaches the partial reflective element BS on the second side of the second lens E2, where it undergoes a second reflection. The light after the second reflection passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizer RP, and the first lens E1, and is finally projected onto a target object (not shown) in space. For example, when this optical system is mounted on an electronic device such as VR, the light after the two reflections is finally projected into the eyes of the user.

[0115] In this example, the structure and parameters of the aperture stop STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG are the same as those in Embodiment 1. Therefore, the basic parameter table of the optical system in this example is exactly the same as the basic parameters shown in Table 1 of Embodiment 1. To avoid redundancy, this example will not describe it in detail; please refer to the relevant content disclosed in Embodiment 1 for details.

[0116] In this example, both the first and second side surfaces of the second lens E2 are aspherical. The higher-order coefficients of each aspherical mirror surface may be the same as those shown in Table 3 of Embodiment 1. Therefore, to avoid redundancy, this example will not describe the higher-order coefficients of each aspherical mirror surface in detail; please refer to the relevant content disclosed in Embodiment 1 for details.

[0117] In this example, the values ​​of the optical technical parameters f2, f, EPD, TD, CTR, and CTQ can be the same as those in Example 1. Therefore, to avoid redundancy, this example will not describe the values ​​of these parameters in detail; please refer to the relevant content disclosed in Example 1 for details.

[0118] Table 5 shows the basic parameters of the second lens in the optical system of Embodiment 3, where the unit of each parameter is millimeters (mm).

[0119] parameter T2a1 T2b1 T2c1 T2d1 T2a2 T2b2 T2c2 T2d2 numerical values 26.99 29.19 31.38 29.19 27.28 29.5 31.72 29.5

[0120] Table 5

[0121] Figure 2A The on-axis chromatic aberration curves of the optical systems of Examples 1 to 3 are shown, which represent the deviation of the focal point of light of different wavelengths after passing through the system. Figure 2B Astigmatism curves of the optical systems of Examples 1 to 3 are shown, representing meridional image plane curvature and sagittal image plane curvature. Figure 2C The distortion curves of the optical systems of Examples 1 to 3 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 2A to 2C It can be seen that the optical systems given in Examples 1 to 3 can achieve good imaging quality.

[0122] Example 4

[0123] The following is for reference Figure 3 The optical system according to Embodiment 4 of this application is described. Figure 3 The optical system of Example 4 is shown.

[0124] like Figure 3 As shown, the optical system includes, from the first side to the second side, the following components in sequence: aperture STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG.

[0125] The first lens E1 has no optical power; its first side surface is flat, and its second side surface is flat. The second lens E2 has positive optical power; its first side surface is convex, and its second side surface is concave. A reflective polarizing element RP is attached to the second side surface of the first lens E1. A quarter-wave plate QWP is attached to the second side surface of the reflective polarizing element RP. A partial reflective element BS is attached to the second side surface of the second lens E2.

[0126] In this example, a light source can be positioned on the image plane IMG. Image light from the image plane IMG passes through the second lens E2 and reaches the reflective polarizer RP, where it undergoes a first reflection. The light after the first reflection passes through the quarter-wave plate QWP and reaches the partial reflective element BS on the second side of the second lens E2, where it undergoes a second reflection. The light after the second reflection passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizer RP, and the first lens E1, and is finally projected onto a target object (not shown) in space. For example, when this optical system is mounted on an electronic device such as VR, the light after the two reflections is finally projected into the eyes of the user.

[0127] Table 6 shows the basic parameters of the optical system of Example 4, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm).

[0128]

[0129] Table 6

[0130] In this example, the effective focal length f2 of the second lens is 49.03 mm, the total effective focal length f of the optical system is 24.21 mm, the entrance pupil diameter EPD of the optical system is 4.50 mm, the distance TD between the first side surface of the first lens and the second side surface of the second lens on the optical axis is 12.82 mm, the center thickness CTR of the reflective polarizing element on the optical axis is 0.09 mm, and the center thickness CTQ of the quarter-wave plate on the optical axis is 0.09 mm.

[0131] Table 7 shows the basic parameters of the second lens in the optical system of Embodiment 4, where all parameters are in millimeters (mm). In this example, the first and second sides of the second lens E2 are both aspherical, and Table 8 gives the higher-order coefficients that can be used for each aspherical mirror in Embodiment 4.

[0132] parameter T2a1 T2b1 T2c1 T2d1 T2a2 T2b2 T2c2 T2d2 numerical values 16.77 24.47 27.49 24.47 17.15 25.03 28.12 25.03

[0133] Table 7

[0134]

[0135]

[0136] Table 8

[0137] Example 5

[0138] The following is for reference Figure 3 The optical system according to Embodiment 5 of this application is described. Figure 3 The optical system of Embodiment 5 is shown.

[0139] like Figure 3 As shown, the optical system includes, from the first side to the second side, the following components in sequence: aperture STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG.

[0140] The first lens E1 has no optical power; its first side surface is flat, and its second side surface is flat. The second lens E2 has positive optical power; its first side surface is convex, and its second side surface is convex. A reflective polarizing element RP is attached to the second side surface of the first lens E1. A quarter-wave plate QWP is attached to the second side surface of the reflective polarizing element RP. A partial reflective element BS is attached to the second side surface of the second lens E2.

[0141] In this example, a light source can be positioned on the image plane IMG. Image light from the image plane IMG passes through the second lens E2 and reaches the reflective polarizer RP, where it undergoes a first reflection. The light after the first reflection passes through the quarter-wave plate QWP and reaches the partial reflective element BS on the second side of the second lens E2, where it undergoes a second reflection. The light after the second reflection passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizer RP, and the first lens E1, and is finally projected onto a target object (not shown) in space. For example, when this optical system is mounted on an electronic device such as VR, the light after the two reflections is finally projected into the eyes of the user.

[0142] In this example, the structure and parameters of the aperture stop STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG are the same as those in Example 4. Therefore, the basic parameter table of the optical system in this example is exactly the same as the basic parameters shown in Table 6 of Example 4. To avoid redundancy, this example will not describe it in detail; please refer to the relevant content disclosed in Example 4 for details.

[0143] In this example, both the first and second side surfaces of the second lens E2 are aspherical. The higher-order coefficients of each aspherical mirror can be the same as those shown in Table 8 of Embodiment 4. Therefore, to avoid redundancy, this example will not describe the higher-order coefficients of each aspherical mirror in detail; please refer to the relevant content disclosed in Embodiment 4 for details.

[0144] In this example, the values ​​of the optical technical parameters f2, f, EPD, TD, CTR, and CTQ can be the same as those in Example 4. Therefore, to avoid redundancy, this example will not describe the values ​​of these parameters in detail; please refer to the relevant content disclosed in Example 4 for details.

[0145] Table 9 shows the basic parameters of the second lens in the optical system of Example 5, where the unit of each parameter is millimeters (mm).

[0146] parameter T2a1 T2b1 T2c1 T2d1 T2a2 T2b2 T2c2 T2d2 numerical values 19.52 26.94 27.49 26.94 19.97 27.56 28.12 27.56

[0147] Table 9

[0148] Example 6

[0149] The following is for reference Figure 3 The optical system according to Embodiment 6 of this application is described. Figure 3 The optical system of Embodiment 6 is shown.

[0150] like Figure 3 As shown, the optical aperture STO, the first lens E1, the reflective polarizing element RP, the quarter-wave plate QWP, the second lens E2, the partial reflective element BS, and the image plane IMG are all present.

[0151] The first lens E1 has no optical power; its first side surface is flat, and its second side surface is flat. The second lens E2 has positive optical power; its first side surface is convex, and its second side surface is convex. A reflective polarizing element RP is attached to the second side surface of the first lens E1. A quarter-wave plate QWP is attached to the second side surface of the reflective polarizing element RP. A partial reflective element BS is attached to the second side surface of the second lens E2.

[0152] In this example, a light source can be positioned on the image plane IMG. Image light from the image plane IMG passes through the second lens E2 and reaches the reflective polarizer RP, where it undergoes a first reflection. The light after the first reflection passes through the quarter-wave plate QWP and reaches the partial reflective element BS on the second side of the second lens E2, where it undergoes a second reflection. The light after the second reflection passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizer RP, and the first lens E1, and is finally projected onto a target object (not shown) in space. For example, when this optical system is mounted on an electronic device such as VR, the light after the two reflections is finally projected into the eyes of the user.

[0153] In this example, the structure and parameters of the aperture stop STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG are the same as those in Example 4. Therefore, the basic parameter table of the optical system in this example is exactly the same as the basic parameters shown in Table 6 of Example 4. To avoid redundancy, this example will not describe it in detail; please refer to the relevant content disclosed in Example 4 for details.

[0154] In this example, both the first and second side surfaces of the second lens E2 are aspherical. The higher-order coefficients of each aspherical mirror can be the same as those shown in Table 8 of Embodiment 4. Therefore, to avoid redundancy, this example will not describe the higher-order coefficients of each aspherical mirror in detail; please refer to the relevant content disclosed in Embodiment 4 for details.

[0155] In this example, the values ​​of the optical technical parameters f2, f, EPD, TD, CTR, and CTQ can be the same as those in Example 4. Therefore, to avoid redundancy, this example will not describe the values ​​of these parameters in detail; please refer to the relevant content disclosed in Example 4 for details.

[0156] Table 10 shows the basic parameters of the second lens in the optical system of Embodiment 6, where the unit of each parameter is millimeters (mm).

[0157] parameter T2a1 T2b1 T2c1 T2d1 T2a2 T2b2 T2c2 T2d2 numerical values 23.64 25.57 27.49 25.57 24.19 26.15 28.12 26.15

[0158] Table 10

[0159] Figure 4A The on-axis chromatic aberration curves of the optical systems of Examples 4 to 6 are shown, which represent the deflection of the focal point of light of different wavelengths after passing through the system. Figure 4B Astigmatism curves of the optical systems of Examples 4 to 6 are shown, representing meridional image plane curvature and sagittal image plane curvature. Figure 4C The distortion curves of the optical systems of Examples 4 to 6 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 4A to 4C It can be seen that the optical systems given in Examples 4 to 6 can achieve good imaging quality.

[0160] Example 7

[0161] The following is for reference Figure 5 The optical system according to Embodiment 7 of this application is described. Figure 5 The optical system of Embodiment 7 is shown.

[0162] like Figure 5 As shown, the optical system includes, from the first side to the second side, the following components in sequence: aperture STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG.

[0163] The first lens E1 has no optical power; its first side surface is flat, and its second side surface is flat. The second lens E2 has positive optical power; its first side surface is convex, and its second side surface is concave. A reflective polarizing element RP is attached to the second side surface of the first lens E1. A quarter-wave plate QWP is attached to the second side surface of the reflective polarizing element RP. A partial reflective element BS is attached to the second side surface of the second lens E2.

[0164] In this example, a light source can be positioned on the image plane IMG. Image light from the image plane IMG passes through the second lens E2 and reaches the reflective polarizer RP, where it undergoes a first reflection. The light after the first reflection passes through the quarter-wave plate QWP and reaches the partial reflective element BS on the second side of the second lens E2, where it undergoes a second reflection. The light after the second reflection passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizer RP, and the first lens E1, and is finally projected onto a target object (not shown) in space. For example, when this optical system is mounted on an electronic device such as VR, the light after the two reflections is finally projected into the eyes of the user.

[0165] Table 11 shows the basic parameters of the optical system of Example 7, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm).

[0166]

[0167]

[0168] Table 11

[0169] In this example, the effective focal length f2 of the second lens is 46.53 mm, the total effective focal length f of the optical system is 25.49 mm, the entrance pupil diameter EPD of the optical system is 4.50 mm, the distance TD between the first side surface of the first lens and the second side surface of the second lens on the optical axis is 18.41 mm, the center thickness CTR of the reflective polarizing element on the optical axis is 0.09 mm, and the center thickness CTQ of the quarter-wave plate on the optical axis is 0.09 mm.

[0170] Table 12 shows the basic parameters of the second lens in the optical system of Embodiment 7, where all parameters are in millimeters (mm). In this example, the first and second sides of the second lens E2 are both aspherical, and Table 13 gives the higher-order coefficients that can be used for each aspherical mirror in Embodiment 7.

[0171] parameter T2a1 T2b1 T2c1 T2d1 T2a2 T2b2 T2c2 T2d2 numerical values 17.57 25.63 28.8 25.63 18.72 27.31 30.68 27.31

[0172] Table 12

[0173] The first side of the second lens The second side of the second lens A4 6.7037E+00 -6.6042E+00 A6 9.3526E+00 9.5036E-01 A8 6.7468E+00 -2.3293E-01 A10 3.5692E+00 1.0545E-01 A12 1.4336E+00 -2.6726E-02 A14 5.1486E-01 2.0109E-02 A16 2.7027E-01 -2.1326E-02 A18 1.1185E-01 8.2970E-03 A20 -1.1578E-02 -5.7957E-03 A22 -8.1392E-03 4.0954E-03 A24 -3.3808E-02 -1.4523E-03 A26 -5.7086E-02 8.8527E-04 A28 -5.8799E-02 -6.8329E-04 A30 -2.5280E-02 1.8440E-04

[0174] Table 13

[0175] Example 8

[0176] The following is for reference Figure 5 The optical system according to Embodiment 8 of this application is described. Figure 5 The optical system of Example 8 is shown.

[0177] like Figure 5 As shown, the optical system includes, from the first side to the second side, the following components in sequence: aperture STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG.

[0178] The first lens E1 has no optical power; its first side surface is flat, and its second side surface is flat. The second lens E2 has positive optical power; its first side surface is convex, and its second side surface is convex. A reflective polarizing element RP is attached to the second side surface of the first lens E1. A quarter-wave plate QWP is attached to the second side surface of the reflective polarizing element RP. A partial reflective element BS is attached to the second side surface of the second lens E2.

[0179] In this example, a light source can be positioned on the image plane IMG. Image light from the image plane IMG passes through the second lens E2 and reaches the reflective polarizer RP, where it undergoes a first reflection. The light after the first reflection passes through the quarter-wave plate QWP and reaches the partial reflective element BS on the second side of the second lens E2, where it undergoes a second reflection. The light after the second reflection passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizer RP, and the first lens E1, and is finally projected onto a target object (not shown) in space. For example, when this optical system is mounted on an electronic device such as VR, the light after the two reflections is finally projected into the eyes of the user.

[0180] In this example, the structure and parameters of the aperture stop STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG are the same as those in Example 4. Therefore, the basic parameter table of the optical system in this example is exactly the same as the basic parameters shown in Table 11 of Example 7. To avoid redundancy, this example will not describe it in detail; please refer to the relevant content disclosed in Example 7 for details.

[0181] In this example, both the first and second side surfaces of the second lens E2 are aspherical. The higher-order coefficients of each aspherical mirror surface can be the same as those shown in Table 13 of Embodiment 7. Therefore, to avoid redundancy, this example will not describe the higher-order coefficients of each aspherical mirror surface in detail; please refer to the relevant content disclosed in Embodiment 7 for details.

[0182] In this example, the values ​​of the optical technical parameters f2, f, EPD, TD, CTR, and CTQ can be the same as those in Example 7. Therefore, to avoid redundancy, this example will not describe the values ​​of these parameters in detail; please refer to the relevant content disclosed in Example 7 for details.

[0183] Table 14 shows the basic parameters of the second lens in the optical system of Embodiment 8, where the unit of each parameter is millimeters (mm).

[0184] parameter T2a1 T2b1 T2c1 T2d1 T2a2 T2b2 T2c2 T2d2 numerical values 20.45 28.22 28.8 28.22 21.78 30.07 30.68 30.07

[0185] Table 14

[0186] Example 9

[0187] The following is for reference Figure 5 The optical system according to Embodiment 9 of this application is described. Figure 5 The optical system of Example 9 is shown.

[0188] like Figure 5 As shown, the optical system includes, from the first side to the second side, the following components in sequence: aperture STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG.

[0189] The first lens E1 has no optical power; its first side surface is flat, and its second side surface is flat. The second lens E2 has positive optical power; its first side surface is convex, and its second side surface is convex. A reflective polarizing element RP is attached to the second side surface of the first lens E1. A quarter-wave plate QWP is attached to the second side surface of the reflective polarizing element RP. A partial reflective element BS is attached to the second side surface of the second lens E2.

[0190] In this example, a light source can be positioned on the image plane IMG. Image light from the image plane IMG passes through the second lens E2 and reaches the reflective polarizer RP, where it undergoes a first reflection. The light after the first reflection passes through the quarter-wave plate QWP and reaches the partial reflective element BS on the second side of the second lens E2, where it undergoes a second reflection. The light after the second reflection passes sequentially through the second lens E2, the quarter-wave plate QWP, the reflective polarizer RP, and the first lens E1, and is finally projected onto a target object (not shown) in space. For example, when this optical system is mounted on an electronic device such as VR, the light after the two reflections is finally projected into the eyes of the user.

[0191] In this example, the structure and parameters of the aperture stop STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, partial reflective element BS, and image plane IMG are the same as those in Example 4. Therefore, the basic parameter table of the optical system in this example is exactly the same as the basic parameters shown in Table 11 of Example 7. To avoid redundancy, this example will not describe it in detail; please refer to the relevant content disclosed in Example 7 for details.

[0192] In this example, both the first and second side surfaces of the second lens E2 are aspherical. The higher-order coefficients of each aspherical mirror surface can be the same as those shown in Table 13 of Embodiment 7. Therefore, to avoid redundancy, this example will not describe the higher-order coefficients of each aspherical mirror surface in detail; please refer to the relevant content disclosed in Embodiment 7 for details.

[0193] In this example, the values ​​of the optical technical parameters f2, f, EPD, TD, CTR, and CTQ can be the same as those in Example 7. Therefore, to avoid redundancy, this example will not describe the values ​​of these parameters in detail; please refer to the relevant content disclosed in Example 7 for details.

[0194] Table 15 shows the basic parameters of the second lens in the optical system of Embodiment 9, where the unit of each parameter is millimeters (mm).

[0195] parameter T2a1 T2b1 T2c1 T2d1 T2a2 T2b2 T2c2 T2d2 numerical values 24.77 26.78 28.8 26.78 26.39 28.53 30.68 28.53

[0196] Table 15

[0197] Figure 6A The on-axis chromatic aberration curves of the optical systems of Examples 7 to 9 are shown, which represent the deviation of the focal point of light of different wavelengths after passing through the system. Figure 6B Astigmatism curves of the optical systems of Examples 7 to 9 are shown, representing meridional image plane curvature and sagittal image plane curvature. Figure 6C The distortion curves of the optical systems of Examples 7 to 9 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 6A to 6C It can be seen that the optical systems given in Examples 7 to 9 can achieve good imaging quality.

[0198] In summary, Examples 1 to 9 satisfy the relationships shown in Tables 16-1, 16-2 and 16-3, respectively.

[0199] Conditional / Example Example 1 Example 2 Example 3 f / EPD 6.49 6.49 6.49 f2 / (T2a1+T2b1+T2c1+T2d1) 1.13 1.05 1.03 R3 / (T2a1+T2c1) 2.92 2.75 2.53 (T2b1+T2d1) / (T2b2+T2d2) 0.99 0.99 0.99 (CT1+CTR+CTQ+T12) / CT2 0.68 0.68 0.68 |R4| / (T2a2+T2b2+T2c2+T2d2) 1.07 0.99 0.98 |R3 / R4|×(T2a1 / T2a2) 1.27 1.27 1.27 f / T2a1 1.52 1.31 1.08 (T2b2+T2d2) / f 1.93 2.13 2.02 CT2 / (T2c2-T2a2) 0.91 1.22 2.52 (T2b2+T2d2) / TD 3.00 3.31 3.14 N2×(T2a1 / T2b1) 1.06 1.12 1.42 f2 / (T2c2+T2d2) 2.01 1.92 1.97

[0200] Table 16-1

[0201]

[0202]

[0203] Table 16-2

[0204] Conditional / Example Example 7 Example 8 Example 9 f / EPD 5.66 5.66 5.66 f2 / (T2a1+T2b1+T2c1+T2d1) 0.48 0.44 0.43 R3 / (T2a1+T2c1) 1.16 1.09 1.00 (T2b1+T2d1) / (T2b2+T2d2) 0.94 0.94 0.94 (CT1+CTR+CTQ+T12) / CT2 0.77 0.77 0.77 |R4| / (T2a2+T2b2+T2c2+T2d2) 2.60 2.40 2.37 |R3 / R4|×(T2a1 / T2a2) 0.19 0.19 0.19 f / T2a1 1.45 1.25 1.03 (T2b2+T2d2) / f 2.14 2.36 2.24 CT2 / (T2c2-T2a2) 0.87 1.17 2.42 (T2b2+T2d2) / TD 2.97 3.27 3.10 N2×(T2a1 / T2b1) 1.20 1.27 1.62 f2 / (T2c2+T2d2) 0.80 0.77 0.79

[0205] Table 16-3

[0206] 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 a VR device. The optical device is equipped with the optical system described above.

[0207] 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, Along the optical axis, from the first side to the second side, the following are included in sequence: A first lens that does not have optical power has a first side surface that is flat and a second side surface that is flat. Reflective polarizing element; Quarter-wave plate; and A second lens with positive optical power has a convex first side surface; It also includes a partial reflective element, which is attached to the second side surface of the second lens; The optical system contains two lenses. The optical system satisfies: 5.38 ≤ f / EPD < 6.5 and 0.4 < f2 / (T2a1+T2b1+T2c1+T2d1) ≤ 1.13, where EPD is the entrance pupil diameter of the optical system, f is the total effective focal length of the optical system, f2 is the effective focal length of the second lens, T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction, T2c1 is the second effective half-aperture of the first side surface of the second lens in the first direction, T2b1 is the third effective half-aperture of the first side surface of the second lens in the second direction perpendicular to the first direction, and T2d1 is the fourth effective half-aperture of the first side surface of the second lens in the second direction, wherein the first side surface of the second lens is the surface closest to the human eye; The optical system satisfies: 0.4 < CT2 / (T2c2-T2a2) ≤ 2.52, where CT2 is the center thickness of the second lens on the optical axis, T2a2 is the first effective half-aperture of the second side of the second lens in the first direction, and T2c2 is the second effective half-aperture of the second side of the second lens in the first direction.

2. The optical system according to claim 1, characterized in that, The optical system satisfies: 0.99≤R3 / (T2a1+T2c1)≤2.92, where R3 is the radius of curvature of the first side surface of the second lens, T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction, and T2c1 is the second effective half-aperture of the first side surface of the second lens in the first direction.

3. The optical system according to claim 1, characterized in that, The optical system satisfies: 0.94≤(T2b1+T2d1) / (T2b2+T2d2)≤0.99, where T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction, wherein the second side surface of the second lens is the side surface closer to the image plane.

4. The optical system according to claim 1, characterized in that, The optical system satisfies: 0.68 ≤ (CT1 + CTR + CTQ + T12) / CT2 < 1.8, where 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, T12 is the distance from the quarter-wave plate to the first side of the second lens on the optical axis, and CT2 is the center thickness of the second lens on the optical axis.

5. The optical system according to claim 1, characterized in that, The optical system satisfies: 0.98≤|R4| / (T2a2+T2b2+T2c2+T2d2)≤2.83, where R4 is the radius of curvature of the second side surface of the second lens, T2a2 is the first effective half-aperture of the second side surface of the second lens in the first direction, T2c2 is the second effective half-aperture of the second side surface of the second lens in the first direction, T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction.

6. The optical system according to claim 1, characterized in that, The optical system satisfies: 0.18≤|R3 / R4|×(T2a1 / T2a2)<1.3, where R3 is the radius of curvature of the first side surface of the second lens, R4 is the radius of curvature of the second side surface of the second lens, T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction, and T2a2 is the first effective half-aperture of the second side surface of the second lens in the first direction.

7. The optical system according to claim 1, characterized in that, The optical system satisfies: 1.0 < f / T2a1 ≤ 1.52, where f is the total effective focal length of the optical system and T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction.

8. The optical system according to claim 1, characterized in that, The optical system satisfies: 1.9 < (T2b2 + T2d2) / f < 2.4, where f is the total effective focal length of the optical system, T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction.

9. The optical system according to claim 1, characterized in that, The optical system satisfies: 2.97≤(T2b2+T2d2) / TD≤4.3, where T2b2 is the third effective half-aperture of the second side surface of the second lens in the second direction, T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction, and TD is the distance from the first side surface of the first lens to the second side surface of the second lens on the optical axis.

10. The optical system according to claim 1, characterized in that, The optical system satisfies: 1.06≤N2×(T2a1 / T2b1)≤1.62, where T2a1 is the first effective half-aperture of the first side surface of the second lens in the first direction, T2b1 is the third effective half-aperture of the first side surface of the second lens in the second direction, and N2 is the refractive index of the second lens.

11. The optical system according to claim 1, characterized in that, The optical system satisfies: 0.77≤f2 / (T2c2+T2d2)≤2.01, where T2c2 is the second effective half-aperture of the second side surface of the second lens in the first direction, and T2d2 is the fourth effective half-aperture of the second side surface of the second lens in the second direction.

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