Optical image capturing system

Abstract

The utility model discloses an optical imaging system, which comprises a lens cone, an imaging part and a spacing element group, wherein the imaging part and the spacing element group are accommodated in the lens cone; the imaging part sequentially comprises a linear polarization film, a reflective polarization element, a quarter-wave plate, a first lens with focal power, a second lens with focal power, a third lens with focal power, a fourth lens with focal power and a partial reflection layer from the first side to the second side along the optical axis, the first lens and the second lens are glued, and the fourth lens and the partial reflection layer are glued together. The third lens is glued with the fourth lens; the spacing element group comprises at least one spacing element; the optical imaging system satisfies:-9.15 < = R1 / (D0s-d0s) < =-6.26, where R1 is the radius of curvature of the first side surface of the first lens, D0s is the outer diameter of the first side end surface of the lens barrel, and d0s is the inner diameter of the first side end surface of the lens barrel.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical devices, in particular to an optical imaging system. BACKGROUND

[0002] The optical imaging system of virtual reality device or augmented reality device is mainly divided into three kinds of optical imaging system adopting aspherical lens, optical imaging system adopting Fresnel lens and catadioptric optical imaging system. Among them, the catadioptric optical imaging system is a major innovation of the optical imaging system itself, and reserves space for the overall design of the virtual reality device or augmented reality device, and has become the mainstream trend of research and development.

[0003] The catadioptric optical imaging system shortens the length of the optical imaging system by light path folding, so as to make the center of gravity of the virtual reality device or augmented reality device move backward, which helps to improve the user experience. However, from the user experience, its weight and thickness are not perfect enough, and because the volume of the lens used is larger than that of the traditional lens, its molding difficulty is higher. When the first lens and the second lens are glued in the catadioptric optical imaging system with large lens volume and in order to compress the total length, the assembly stability between the lens and the lens barrel is easily reduced. CONTENT OF THE UTILITY MODEL

[0004] The present application provides an optical imaging system, which comprises a lens barrel and an imaging part and a spacer element group contained in the lens barrel, the imaging part comprises a first lens with optical power, a second lens with optical power, a third lens with optical power, a fourth lens with optical power, a quarter wave plate, a reflective polarizing element, a linear polarizing film and a partial reflection layer, wherein the first lens, the second lens, the third lens and the fourth lens are arranged in order along the optical axis from the first side to the second side, the first lens is glued with the second lens, the third lens is glued with the fourth lens, the quarter wave plate is attached to the first side surface of the first lens, the reflective polarizing element is attached to the first side surface of the quarter wave plate, the linear polarizing film is attached to the first side surface of the reflective polarizing element, and the partial reflection layer is attached to the second side surface of the fourth lens; the number of lenses with optical power in the imaging part is four; the spacer element group comprises at least one spacer element; and the optical imaging system satisfies: -9.15≤R1 / (D0s-d0s)≤-6.26, wherein R1 is the curvature radius of the first side surface of the first lens, D0s is the outer diameter of the first side end surface of the lens barrel, and d0s is the inner diameter of the first side end surface of the lens barrel.

[0005] According to an exemplary embodiment of the present application, the spacer element group includes a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; the optical imaging system satisfies: 0.47≤(CT1+CT2) / EP02≤0.89, wherein CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, and EP02 is the distance between the first side end surface of the lens barrel and the first side surface of the second spacer element in the direction of the optical axis.

[0006] According to an exemplary embodiment of the present application, the spacer element group includes a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; the optical imaging system satisfies: 0.56≤T23 / CP2≤0.86, wherein T23 is the distance between the second side surface of the second lens and the first side surface of the third lens on the optical axis, and CP2 is the maximum thickness of the second spacer element.

[0007] According to an exemplary embodiment of the present application, the spacer element group includes a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; the optical imaging system satisfies: 2.63≤(CT3+CT4) / CP2≤3.45, wherein CT3 is the center thickness of the third lens on the optical axis, CT4 is the center thickness of the fourth lens on the optical axis, and CP2 is the maximum thickness of the second spacer element.

[0008] According to an exemplary embodiment of the present application, the spacer element group includes a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; the optical imaging system satisfies: 4.06≤|f2 / d2s|≤5.12, wherein f2 is the effective focal length of the second lens, and d2s is the inner diameter of the first side surface of the second spacer element.

[0009] According to an exemplary embodiment of the present application, the spacer element group includes a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; the optical imaging system satisfies: -5.05≤R4 / d2s≤-1.3, wherein R4 is the radius of curvature of the second side surface of the second lens, and d2s is the inner diameter of the first side surface of the second spacer element.

[0010] According to an exemplary embodiment of the present application, the spacer element group includes a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; the optical imaging system satisfies: 1.23≤|R7 / d2m|≤1.91, wherein R7 is the radius of curvature of the first side surface of the fourth lens, and d2m is the inner diameter of the second side surface of the second spacer element.

[0011] According to the exemplary embodiments of the present application, the spacer element group comprises a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; the optical imaging system satisfies: 3.16≤|f3 / D2m|≤5.93, wherein f3 is the effective focal length of the third lens, and D2m is the outer diameter of the second side surface of the second spacer element.

[0012] According to the exemplary embodiments of the present application, the optical imaging system satisfies: -19.88≤R8 / (D0m-d0m)≤-14.62, wherein R8 is the curvature radius of the second side surface of the fourth lens, D0m is the outer diameter of the second side end surface of the lens barrel, and d0m is the inner diameter of the second side end surface of the lens barrel.

[0013] According to the exemplary embodiments of the present application, the optical imaging system satisfies: -58.64mm 2 ≤f1*(dlp+drp+dqwp)≤-21.61mm 2 , wherein f1 is the effective focal length of the first lens, dlp is the central thickness of the linear polarization film on the optical axis, drp is the central thickness of the reflective polarization element on the optical axis, and dqwp is the central thickness of the quarter-wave plate on the optical axis.

[0014] According to the exemplary embodiments of the present application, the first side surface of the first lens is a concave surface; the second side surface of the second lens is a convex surface; and the second side surface of the fourth lens is a convex surface.

[0015] According to the exemplary embodiments of the present application, the first lens has a negative focal power; the second lens has a positive or negative focal power; the third lens has a positive or negative focal power; and the fourth lens has a positive focal power.

[0016] The optical imaging system provided by the present application can fold the optical path while ensuring the imaging quality by setting the reflective polarization element, the quarter-wave plate, the partial reflection layer and the like, effectively shortens the body length of the optical imaging system, and adjusts the width of the lens barrel for bearing to an appropriate range by controlling the range of the condition R1 / (D0s-d0s), thereby restricting the shape of the first lens, and solves the problem of poor assembly stability between the first lens and the second lens and the lens barrel when the first lens and the second lens are cemented, while ensuring that the optical imaging system can be well converged into the human eye. BRIEF DESCRIPTION OF DRAWINGS

[0017] Other characteristics, objects and advantages of the present application will become more apparent from the following detailed description of non-restrictive embodiments, made with reference to the attached drawings. Among them:

[0018] Figure 1 The structure arrangement and part of the parameter schematic diagram of an optical imaging system of the present application are shown.

[0019] Figure 2 A structural arrangement diagram of an optical imaging system of the present application is shown;

[0020] Figure 3 A structural diagram of an optical imaging system of the embodiment 1 of the present application is shown;

[0021] Figure 4 A structural diagram of an optical imaging system of the embodiment 2 of the present application is shown;

[0022] Figure 5 A structural diagram of an optical imaging system of the embodiment 3 of the present application is shown

[0023] Figure 6 Axial chromatic aberration curves (A1), astigmatic curves (B1) and distortion curves (C1) of the optical imaging systems of the embodiments 1 to 3 of the present application are shown;

[0024] Figure 7 A structural diagram of an optical imaging system of the embodiment 4 of the present application is shown;

[0025] Figure 8 A structural diagram of an optical imaging system of the embodiment 5 of the present application is shown;

[0026] Figure 9 A structural diagram of an optical imaging system of the embodiment 6 of the present application is shown;

[0027] Figure 10 Axial chromatic aberration curves (A2), astigmatic curves (B2) and distortion curves (C2) of the optical imaging systems of the embodiments 4 to 6 of the present application are shown;

[0028] Figure 11 A structural diagram of an optical imaging system of the embodiment 7 of the present application is shown;

[0029] Figure 12 A structural diagram of an optical imaging system of the embodiment 8 of the present application is shown;

[0030] Figure 13 A structural diagram of an optical imaging system of the embodiment 9 of the present application is shown;

[0031] Figure 14 Axial chromatic aberration curves (A3), astigmatic curves (B3) and distortion curves (C3) of the optical imaging systems of the embodiments 7 to 9 of the present application are shown. DETAILED DESCRIPTION

[0032] For a better understanding of the present application, various aspects of the present application will be described in greater detail below with reference to the accompanying drawings. It is to be noted that these detailed descriptions are merely descriptive of exemplary embodiments of the present application and are not intended in any way to limit the scope of the present application. Throughout the specification, like drawing reference numerals will be understood to refer to like parts throughout the specification and the drawings.

[0033] It is to be noted that the terms first, second, third, etc. are used herein only to distinguish one feature from another, and do not denote any limitation on the features. Thus, the first lens discussed below can also be referred to as a second lens or a third lens without departing from the teachings of the present application.

[0034] In the drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shape of the spherical or aspherical surface shown in the drawings is shown by way of example. That is, the shape of the spherical or aspherical surface is not limited to the shape of the spherical or aspherical surface shown in the drawings. The drawings are merely examples and are not drawn to scale.

[0035] Herein, if a lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The paraxial region refers to a region near the optical axis. The surface of each lens closest to the first side (e.g., the side of the human eye) is referred to as the first side surface of the lens, and the surface of each lens closest to the second side (e.g., the side of the display screen) is referred to as the second side surface of the lens.

[0036] The optical imaging system of the exemplary embodiments of the present application can be simulated using, for example, software such as ZEMAX, CODEV, etc., and / or tools, and optionally, the optical imaging system can be simulated using the CODEV software. In the process of simulating using software such as the above and / or tools, the surface shape of each lens can be appropriately adjusted according to the surface shape model provided with the software and / or the tools used.

[0037] It is also to be understood that the terms "comprise" and / or "have", when used in this specification, denote the presence of stated features, elements and / or components but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. Furthermore, when describing the embodiments of the present application, the use of "may" means "one or more embodiments of the present application". Also, the term "exemplary" is intended to refer to an example or illustration.

[0038] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0039] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The following embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but should not be understood as a limitation on the patent scope of the present application. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application.

[0040] The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0041] Figure 1 An exemplary structural arrangement and part of the parameters of an optical imaging system of the present application are shown in the schematic diagram, so as to better understand the present application. As shown in Figure 1 D0s is the outer diameter of the first side end surface of the lens barrel, d0s is the inner diameter of the first side end surface of the lens barrel, D2s is the outer diameter of the first side surface of the second spacing element, d2s is the inner diameter of the first side surface of the second spacing element, d2m is the inner diameter of the second side surface of the second spacing element, D2m is the outer diameter of the second side surface of the second spacing element, d0m is the inner diameter of the second side end surface of the lens barrel, D0m is the outer diameter of the second side end surface of the lens barrel, EP02 is the distance between the first side end surface of the lens barrel and the first side surface of the second spacing element along the optical axis direction, CP2 is the maximum thickness of the second spacing element, and L is the distance between the first side end surface and the second side end surface of the lens barrel along the optical axis direction.

[0042] Figure 2 An exemplary structural arrangement of an optical imaging system of the present application is shown in the schematic diagram. As shown in Figure 2 The optical imaging system of the present application includes a receiving part J, an imaging part C and a transmitting part F. The transmitting part F is located at the second side of the system and can transmit image light, for example, can be a display screen. The imaging part C can fold and reflect the light rays of the image light transmitted by the transmitting part F multiple times, and finally project to the receiving part J. The receiving part J is located at the first side of the system, for example, can be a human eye.

[0043] Reference Figure 2 , Figures 3 to 5 , Figures 7 to 9 , Figures 11 to 13The first aspect of the present application provides an optical imaging system, wherein the imaging part of the optical imaging system comprises a first lens, a second lens, a third lens and a fourth lens with optical power arranged in sequence from a first side to a second side along an optical axis.

[0044] In an exemplary embodiment, the number of lenses with optical power in the imaging part is four. Each lens has at least a first side surface facing the first side and a second side surface facing the second side.

[0045] In an exemplary embodiment, the first lens has negative optical power. The first side surface of the first lens is concave, and the second side surface is convex.

[0046] In an exemplary embodiment, the second lens has positive or negative optical power. The first side surface of the second lens is concave, and the second side surface is convex.

[0047] In an exemplary embodiment, the first lens and the second lens form a cemented lens, i.e. the second side surface of the first lens is cemented with the first side surface of the second lens.

[0048] In an exemplary embodiment, the third lens has positive or negative optical power. The first side surface of the third lens is concave, and the second side surface is convex, or the first side surface of the third lens is convex, and the second side surface is concave.

[0049] In an exemplary embodiment, the fourth lens has positive optical power. The first side surface of the fourth lens is convex or concave, and the second side surface is convex. The fourth lens has positive optical power and can converge light rays, and in combination with the lens with negative optical power, the aberration of the entire optical imaging system can be effectively adjusted, and the imaging quality can be improved.

[0050] In an exemplary embodiment, the third lens and the fourth lens form a cemented lens, i.e. the second side surface of the third lens is cemented with the first side surface of the fourth lens. For example, when the second side surface of the third lens is convex, the first side surface of the fourth lens is concave, or when the second side surface of the third lens is concave, the first side surface of the fourth lens is convex.

[0051] In an exemplary embodiment, the first side surface of the first lens is concave, the second side surface of the second lens is convex, and the second side surface of the fourth lens is convex. The concave first side surface of the first lens can increase the field of view, thereby increasing the visual range. The convex second side surface of the second lens and the convex second side surface of the fourth lens can converge the light rays emitted to the image plane as much as possible under the premise of keeping the third lens small in thickness, thereby reducing the size of the device display and reducing the cost.

[0052] In an exemplary embodiment, the second side surface of the second lens and the first side surface of the third lens can have a spacing distance along the optical axis, and the spacing distance can be an air gap.

[0053] In the example embodiment, each lens has an effective diameter region capable of transmitting light and a non-effective diameter region surrounding the effective diameter region. For example, as shown in FIG. 1, the effective diameter region of the first side of the first lens is the region between the center point Q1 and the edge point Q2 of the first side of the first lens. Figure 2 As shown in FIG. 1, the center point Q1 of the first side of the first lens is the intersection of the first side of the first lens and the optical axis, and the edge point Q2 of the first side of the first lens is the critical point between the effective diameter region and the non-effective diameter region of the first side of the first lens.

[0054] Referring to FIG. 1, Figures 3 to 5 Figures 7 to 9 Figures 11 to 13 The imaging part of the optical imaging system of the present application further comprises a quarter-wave plate, a reflective polarizing element, a linear polarizing film and a partial reflection layer.

[0055] In the example embodiment, the linear polarizing film, the reflective polarizing element and the quarter-wave plate are sequentially attached to the first side of the first lens from the first side to the second side, i.e., the quarter-wave plate is attached to the first side of the first lens, the reflective polarizing element is attached to the first side of the quarter-wave plate, and the linear polarizing film is attached to the first side of the reflective polarizing element. The quarter-wave plate is used to change the polarization state of light, for example, to convert circularly polarized light into linearly polarized light, or to convert linearly polarized light into circularly polarized light. Circularly polarized light can include right-handed circularly polarized light or left-handed circularly polarized light. Linearly polarized light can include S linearly polarized light or P linearly polarized light. The reflective polarizing element is used to reflect linearly polarized light in a predetermined direction and transmit linearly polarized light orthogonal to the predetermined direction. For example, the reflective polarizing element can reflect S linearly polarized light and transmit P linearly polarized light, or the reflective polarizing element can reflect P linearly polarized light and transmit S linearly polarized light.

[0056] In the example embodiment, the partial reflection layer is attached to the second side of the fourth lens. For example, the partial reflection layer can have a semi-transmissive and semi-reflective effect on light. By providing the partial reflection layer on the second side of the fourth lens in combination with the reflective polarizing element and the quarter-wave plate, the light can be folded multiple times, effectively reducing the length of the optical imaging system.

[0057] In the example embodiment, the optical imaging system can further comprise a diaphragm. The diaphragm is beneficial for converging light entering the optical imaging system, reducing the maximum light transmission aperture of the system, and reducing the assembly sensitivity of the system, to further improve the imaging quality of the system. It should be noted that the diaphragm can be provided between the lenses or on one side as needed. For example, the diaphragm is provided on the first side of the first lens.

[0058] ​​In the present application, by setting a reflective polarizing element, a quarter-wave plate, a partial reflection layer, etc., the light can be folded and reflected multiple times in the imaging part, the optical path can be folded under the premise of ensuring the imaging quality, and the length of the optical imaging system body is effectively shortened. For example, the image light from the emitting part passes through the partial reflection layer, the fourth lens, the third lens, the second lens, the first lens, and the quarter-wave plate in sequence, and is reflected for the first time at the reflective polarizing element. The first reflected light passes through the quarter-wave plate, the first lens, the second lens, the third lens, and the fourth lens in sequence, and is reflected for the second time at the partial reflection layer. The second reflected light passes through the fourth lens, the third lens, the second lens, the first lens, the quarter-wave plate, the reflective polarizing element, the linear polarizing film, and the diaphragm in sequence, and is finally projected to the receiving part.

[0059] In an exemplary embodiment, the optical imaging system further comprises a spacer element group, which can include at least one spacer element. It should be understood that the present application does not specifically limit the number of spacer elements. The spacer element helps the optical imaging system to intercept the excess folded reflection light path, reduce the generation of stray light and ghosting, and improve the imaging quality.

[0060] In an exemplary embodiment, the spacer element group includes a second spacer element. The second spacer element is located between the second lens and the third lens, and the first side surface of the second spacer element is at least partially in contact with the second side surface of the second lens, and the second side surface of the second spacer element is at least partially in contact with the first side surface of the third lens.

[0061] In an exemplary embodiment, the optical imaging system further comprises a lens barrel. The imaging part and the spacer element group are disposed in the lens barrel. The lens barrel includes a first side end surface, a second side end surface, an outer annular surface, and an inner annular surface, wherein the end surface of the lens barrel closest to the first side is the first side end surface of the lens barrel, and the end surface of the lens barrel closest to the second side is the second side end surface of the lens barrel; in the direction perpendicular to the optical axis, the surface of the lens barrel farthest from the optical axis is the outer annular surface, and the surface of the lens barrel closest to the optical axis is the inner annular surface.

[0062] In an exemplary embodiment, the outer periphery of at least one lens in the imaging part can have a cut edge portion and a non-cut edge portion, and the outer diameter of the cut edge portion of the lens can be smaller than the outer diameter of the non-cut edge portion of the lens. When the outer periphery of the lens has a cut edge portion, the outer diameter of the lens generally refers to the outer diameter of the non-cut edge portion of the lens. For example, the outer diameter of the first side surface of the lens refers to the outer diameter of the part of the non-cut edge portion of the lens closest to the first side, and the outer diameter of the second side surface of the lens refers to the outer diameter of the part of the non-cut edge portion of the lens closest to the second side.

[0063] In the example embodiment, the outer peripheral surface of at least one of the spacer elements in the group of spacer elements can have a chamfered portion and a non-chamfered portion, and the outer diameter of the chamfered portion of the spacer element can be smaller than the outer diameter of the non-chamfered portion of the spacer element. When the outer peripheral surface of the spacer element has a chamfered portion, the outer diameter of the spacer element generally refers to the outer diameter of the non-chamfered portion of the spacer element. For example, the outer diameter of the first side surface of the spacer element refers to the outer diameter of the portion of the non-chamfered portion of the spacer element closest to the first side surface, and the outer diameter of the second side surface of the spacer element refers to the outer diameter of the portion of the non-chamfered portion of the spacer element closest to the second side surface.

[0064] In the example embodiment, the optical imaging system of the present application can further include a filter as needed, which can filter light rays having different wavelengths. For example, the filter can be disposed between the partially reflective layer and the emitting portion.

[0065] In the example embodiment, the optical imaging system satisfies -9.15≤R1 / (D0s-d0s)≤-6.26, where R1 is the radius of curvature of the first side surface of the first lens, D0s is the outer diameter of the first side end surface of the lens barrel, and d0s is the inner diameter of the first side end surface of the lens barrel. By controlling the above condition, the width of the lens barrel for bearing can be adjusted to an appropriate range, and the shape of the first lens is constrained, which solves the problem of poor assembly stability between the first lens and the second lens when they are cemented, while ensuring that the optical imaging system can be well converged into the human eye.

[0066] Table 1 is a structure sensitivity analysis table of the face type variation amount of the first side surface of the first lens in the optical imaging system, and Table 2 is an optical sensitivity analysis table of the face type variation amount of the first side surface of the first lens in the optical imaging system. In Table 1, surface S1 is the first side surface of the first lens. ΔS1PV (i.e., structure sensitivity) is the face type variation amount of the first side surface of the first lens. Under the action of stress, the structure of the non-effective diameter region of the first side surface of the first lens will be deformed, the center point and the edge point of the first side surface of the first lens will be displaced, and thus the face type precision will be changed. In Table 2, Q1 is the center point of the first side surface of the first lens, and Q2 is the edge point of the first side surface of the first lens.

[0067] In Table 1, surface S1 is the first side surface of the first lens. ΔS1PV (i.e., structure sensitivity) is the face type variation amount of the first side surface of the first lens. Under the action of stress, the structure of the non-effective diameter region of the first side surface of the first lens will be deformed, the center point and the edge point of the first side surface of the first lens will be displaced, and thus the face type precision will be changed. In Table 1, surface S1 is the first side surface of the first lens. ΔS1PV (i.e., structure sensitivity) is the face type variation amount of the first side surface of the first lens. Under the action of stress, the structure of the non-effective diameter region of the first side surface of the first lens will be deformed, the center point and the edge point of the first side surface of the first lens will be displaced, and thus the face type precision will be changed. In Table 2, Q1 is the center point of the first side surface of the first lens, and Q2 is the edge point of the first side surface of the first lens. Figure 2

[0068] ​In Table 2, 0.8S.Peak can be the S-curve peak value of the MTF curve under 0.8 field of view, 0.8M.Peak can be the M-curve peak value of the MTF curve under 0.8 field of view, "S" is the sagittal curve, and "M" is the meridional curve. When ΔS1PV changes, 0.8S.Peak and / or 0.8M.Peak changes with the change of ΔS1PV, and the change amount of 0.8S.Peak and / or 0.8M.Peak can be the optical sensitivity. Wherein, S+ means that ΔS1PV increases by 1 μm, and S- means that ΔS1PV decreases by 1 μm. The comprehensive sensitivity can be the product of the structural sensitivity and the optical sensitivity. It should be understood that the smaller the absolute value of the optical sensitivity is, the better the optical sensitivity is; the smaller the absolute value of the comprehensive sensitivity is, the better the comprehensive sensitivity is.

[0069] Table 1

[0070]

[0071] Table 2

[0072]

[0073]

[0074] The structural sensitivity represents the change amount of the surface shape of the first side of the first lens when a certain load is applied to the system. The same load is applied to system 1, system 2 and system 3, and the structural part (i.e., the non-effective diameter area) of the first side of the first lens of system 1, system 2 and system 3 respectively receives the same external force, and the center point and the edge point of the first side of the first lens produce displacement under the influence of stress. As shown in Table 1, through simulation, the structural sensitivity of system 1, system 2 and system 3 is 1.57E-02 μm, 8.64E-01 μm and 7.75E+00 μm respectively, it can be seen that the structural sensitivity of system 1 is smaller, i.e., the displacement amount is smaller, the structural sensitivity of system 1 is better, and the structural sensitivity of system 2 and system 3 is poorer.

[0075] The optical sensitivity represents the change amount of the MTF peak value of the system when the displacement amount of the system is certain. It should be noted that when the structural sensitivity is positive, the optical sensitivity takes the sensitivity value in the positive direction (i.e., S+). As can be seen from the table, ΔS1PV is positive, therefore, the optical sensitivity takes the sensitivity value of S+. As shown in Table 2, through simulation, when ΔS1PV increases by 1 μm, the change amount of 0.8S.Peak of system 1, system 2 and system 3 is-0.73%, -0.93% and -0.79% respectively, and the change amount of 0.8M.Peak is-0.59%, -0.68% and -0.83% respectively, it can be seen that the MTF peak value of system 1 is less affected by the deformation, the optical sensitivity of system 1 is better, and the optical sensitivity of system 2 and system 3 is poorer.

[0076] The comprehensive sensitivity represents the influence of the deformation on the MTF peak value of the system. As shown in Table 2, the comprehensive sensitivity of the S direction of the system 1, the system 2 and the system 3 is-1.15E-02 μm, -8.04E-01 μm and-6.12E+00 μm respectively, and the comprehensive sensitivity of the M direction is-9.26E-03 μm, -5.88E-01 μm and-6.43E+00 μm respectively, it can be seen that the stress deformation of the system 1 is smaller, and the influence of the deformation on the MTF peak value is smaller, the comprehensive sensitivity of the system 1 is smaller, and the assembly stability is better, and the assembly stability of the system 2 and the system 3 is poorer.

[0077] It can be known from the above analysis that, by making the optical imaging system satisfy-9.15≤R1 / (D0s-d0s)≤-6.26, the first lens can have a smaller deformation amount, the structural sensitivity and the optical sensitivity of the optical imaging system can be reduced, thereby the comprehensive sensitivity of the optical imaging system is reduced, and the assembly stability of the optical imaging system is improved. The assembly stability of the optical imaging system outside the range of the above condition is poorer.

[0078] In the example embodiment, the spacer element group includes a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; and the optical imaging system satisfies: 0.47≤(CT1+CT2) / EP02≤0.89, wherein CT1 is the central thickness of the first lens on the optical axis, CT2 is the central thickness of the second lens on the optical axis, and EP02 is the distance between the first side end surface of the lens barrel and the first side surface of the second spacer element along the optical axis. Since a larger thickness of the second spacer element will generate more stray light, by controlling the above condition, the reflection of the excess light is reduced, thereby improving the stray light and improving the imaging quality of the system. At the same time, by controlling the ratio of the central thickness and the edge thickness of the first lens and the second lens within a certain range, the processing and forming of the first lens and the second lens and the cementing are facilitated.

[0079] In the example embodiment, the spacer element group includes a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; and the optical imaging system satisfies: 0.56≤T23 / CP2≤0.86, wherein T23 is the distance between the second side surface of the second lens and the first side surface of the third lens on the optical axis, and CP2 is the maximum thickness of the second spacer element. By controlling the above condition, on the one hand, the ratio of the central thickness and the edge thickness of the second lens and the third lens can be limited within a certain range, which is conducive to the forming of the second lens and the third lens, and is also conducive to the assembly stability of the cemented lens composed of the first lens and the second lens and the cemented lens composed of the third lens and the fourth lens; on the other hand, by controlling the distance between the second side surface of the second lens and the first side surface of the third lens on the optical axis, the field curvature of the system can be controlled, and the imaging quality of the system is improved.

[0080] In the example embodiment, the spacer element group includes a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; the optical imaging system satisfies: 2.63≤(CT3+CT4) / CP2≤3.45, wherein CT3 is the central thickness of the third lens on the optical axis, CT4 is the central thickness of the fourth lens on the optical axis, and CP2 is the maximum thickness of the second spacer element. By controlling the above condition, the assembly of the third lens and the fourth lens is facilitated, the deformation of the third lens and the fourth lens after assembly with the spacer element group is reduced, and the assembly stability of the system is improved.

[0081] In the example embodiment, the spacer element group includes a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; the optical imaging system satisfies: 4.06≤|f2 / d2s|≤5.12, wherein f2 is the effective focal length of the second lens, and d2s is the inner diameter of the first side surface of the second spacer element. By controlling the effective focal length of the second lens within a certain range, the positive spherical aberration can be generated, and the negative spherical aberration generated by other lenses of the system is balanced, so that the imaging quality of the system on the axis is good; secondly, by controlling the inner diameter of the first side surface of the second spacer element, the processability of the second spacer element is improved on the basis of ensuring the bearing effect.

[0082] In the example embodiment, the spacer element group includes a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; the optical imaging system satisfies: -5.05≤R4 / d2s≤-1.3, wherein R4 is the curvature radius of the second side surface of the second lens, and d2s is the inner diameter of the first side surface of the second spacer element. By controlling the above condition, on the one hand, the shape of the second lens is constrained, which is conducive to reducing the sensitivity of the second lens, thereby improving the yield of assembly; on the other hand, the matching of the refractive properties of the second spacer element and the second lens can be ensured, and the risk of stray light or reduction of light efficiency caused by the deviation of useless light and the shielding of useful light can be prevented.

[0083] In the example embodiment, the spacer element group includes a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; the optical imaging system satisfies: 1.23≤|R7 / d2m|≤1.91, wherein R7 is the curvature radius of the first side surface of the fourth lens, and d2m is the inner diameter of the second side surface of the second spacer element. By controlling the above condition, on the one hand, the shape of the fourth lens is constrained, which is conducive to reducing the sensitivity of the fourth lens, thereby improving the yield of assembly; on the other hand, the light path reflected by the effective diameter edge mechanism of the first side surface of the fourth lens to the inside of the imaging part through the small bevel can be shielded to generate stray light.

[0084] In the example embodiment, the group of spacer elements comprises a second spacer element located between the second lens and the third lens and in contact with the second side surface of the second lens; the optical imaging system satisfies: 3.16≤|f3 / D2m|≤5.93, where f3 is the effective focal length of the third lens, and D2m is the outer diameter of the second side surface of the second spacer element. By controlling the effective focal length of the third lens within a certain range, the positive spherical aberration can be generated and balanced with the negative spherical aberration generated by other lenses of the system, so that the imaging quality of the system on the axis is good; secondly, by controlling the outer diameter of the second side surface of the second spacer element, the processability of the second spacer element is improved on the basis of ensuring the bearing effect.

[0085] In the example embodiment, the optical imaging system satisfies: -19.88≤R8 / (D0m-d0m)≤-14.62, where R8 is the curvature radius of the second side surface of the fourth lens, D0m is the outer diameter of the second side end surface of the lens barrel, and d0m is the inner diameter of the second side end surface of the lens barrel. By controlling the above condition, on the one hand, the shape of the fourth lens is constrained, which is conducive to reducing the sensitivity of the fourth lens, thereby improving the yield of assembly, and on the other hand, the refraction of light by the lens barrel and the lens can be matched; by controlling the inner and outer diameter sizes of the second side end surface of the lens barrel, not only the feasibility of the lens barrel forming can be ensured, but also the risk of stray light or reduction of light efficiency caused by the deviation of useless light and the shielding of useful light can be prevented.

[0086] In the example embodiment, the optical imaging system satisfies: -58.64mm 2 ≤f1*(dlp+drp+dqwp)≤-21.61mm 2 where f1 is the effective focal length of the first lens, dlp is the central thickness of the linear polarization film on the optical axis, drp is the central thickness of the reflective polarization element on the optical axis, and dqwp is the central thickness of the quarter-wave plate on the optical axis. By controlling the above condition, the reasonable distribution of optical power can be realized, and the thickness of the first lens is small, which is conducive to the miniaturization of the system.

[0087] In the embodiment of the present application, at least one of the surfaces of the first lens, the second lens, the third lens and the fourth lens is a non-spherical surface. The characteristic of the aspherical lens is that the curvature is continuously changed from the center of the lens to the periphery of the lens. Unlike the spherical lens with constant curvature from the center of the lens to the periphery of the lens, the aspherical lens has better curvature radius characteristics, has the advantages of improving distortion aberration and improving astigmatism aberration. After adopting the aspherical lens, the aberration that occurs during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0088] The second aspect of the present application provides an optical imaging system, comprising a lens barrel, and an imaging part and a spacer element group accommodated in the lens barrel, the imaging part comprising a first lens having optical power, a second lens having optical power, a third lens having optical power, a fourth lens having optical power, a quarter-wave plate, a reflective polarizing element, a linear polarizing film and a partial reflection layer, wherein the first lens, the second lens, the third lens and the fourth lens are sequentially arranged along an optical axis from a first side to a second side, the first lens is cemented with the second lens, the third lens is cemented with the fourth lens, the quarter-wave plate is attached to a first side surface of the first lens, the reflective polarizing element is attached to a first side surface of the quarter-wave plate, the linear polarizing film is attached to a first side surface of the reflective polarizing element, and the partial reflection layer is attached to a second side surface of the fourth lens; the imaging part has four lenses having optical power; the spacer element group comprises at least one spacer element; and the optical imaging system satisfies: 0.47≤(CT1+CT2) / EP02≤0.89, wherein CT1 is a center thickness of the first lens along the optical axis, CT2 is a center thickness of the second lens along the optical axis, and EP02 is a distance between a first side end surface of the lens barrel and a first side surface of the second spacer element along the optical axis.

[0089] The present application sets the reflective polarizing element, the quarter-wave plate, the partial reflection layer and the like, so that the light can be folded and reflected multiple times in the imaging part, the optical path can be folded under the premise of ensuring the imaging quality, the body length of the optical imaging system is effectively shortened, and by controlling (CT1+CT2) / EP02, the reflection of the excess light is reduced, the stray light is improved, the imaging quality of the system is improved, and by controlling the ratio of the center thickness and the edge thickness of the first lens and the second lens within a certain range, the processing and molding of the first lens and the second lens and the cementing are facilitated.

[0090] Those skilled in the art will understand that the number of lenses and other elements constituting the optical imaging system can be changed without departing from the technical solutions claimed by the present application, to obtain the various results and advantages described in the present specification.

[0091] Specific embodiments of the optical imaging system applicable to the above embodiments will be further described below with reference to the accompanying drawings. Specifically, the optical imaging system according to the embodiments 1 to 3 of the present application is described with reference to Figures 3 to 6 The optical imaging system according to the embodiments 1 to 3 of the present application is described with reference to Figures 7 to 10 The optical imaging system according to the embodiments 4 to 6 of the present application is described with reference to Figures 11 to 14 The optical imaging system according to the embodiments 7 to 9 of the present application is described.

[0092] Embodiment 1

[0093] Figure 3 The structure schematic diagram of the optical imaging system of the embodiment 1 of the present application is shown. As shown in Figure 3As shown, the optical imaging system comprises a lens barrel P0, an imaging part C and a spacer element group arranged in the lens barrel P0, a receiving part J (not shown) located at the first side of the lens barrel P0 and an emitting part F (not shown) located at the second side of the lens barrel P0.

[0094] The imaging part C comprises, in order along the optical axis from the first side to the second side, a linear polarizer film LP, a reflective polarizing element RP, a quarter wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4 and a partially reflective layer BS. A stop STO (not shown) can be located at the first side of the first lens E1. In the present embodiment, the first side refers to the side of the human eye and the second side refers to the side of the display screen. By way of example, the receiving part J can be the human eye and the emitting part F can be the display screen.

[0095] The first lens E1 has a negative optical power, the first side surface S1 is concave and the second side surface S2 is convex. The second lens E2 has a positive optical power, the first side surface S3 is concave and the second side surface S4 is convex. The third lens E3 has a positive optical power, the first side surface S5 is concave and the second side surface S6 is convex. The fourth lens E4 has a positive optical power, the first side surface S7 is concave and the second side surface S8 is convex. The second side surface S2 of the first lens E1 is cemented to the first side surface S3 of the second lens E2. The second side surface S6 of the third lens E3 is cemented to the first side surface S7 of the fourth lens E4. The quarter wave plate QWP is attached to the first side surface S1 of the first lens E1, the reflective polarizing element RP is attached to the first side surface of the quarter wave plate QWP and the linear polarizer film LP is attached to the first side surface of the reflective polarizing element RP. The partially reflective layer BS is attached to the second side surface S8 of the fourth lens E4.

[0096] The spacer elements are located between the non-effective diameter regions of the lenses and the spacer element group comprises a second spacer element P2. The second spacer element P2 is located between the second lens E2 and the third lens E3 and the first side surface of the second spacer element P2 is at least partially in contact with the second side surface S4 of the second lens E2 and the second side surface of the second spacer element P2 is at least partially in contact with the first side surface S5 of the third lens E3.

[0097] In the present example, the image light from the emitting part F enters the receiving part J after multiple times of fold reflection by the imaging part C. Specifically, the image light from the emitting part F sequentially passes through the partial reflection layer BS, the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter wave plate QWP, and is reflected for the first time at the reflective polarizing element RP. The first reflected light sequentially passes through the quarter wave plate QWP, the first lens E1, the second lens E2, the third lens E3, and the fourth lens E4, and is reflected for the second time at the partial reflection layer BS. The second reflected light sequentially passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter wave plate QWP, the reflective polarizing element RP, the linear polarizing film LP, and the stop STO, and is finally projected to the receiving part J.

[0098] Table 3 shows a basic parameter table of each element of the optical imaging system of Example 1, wherein the units of the radius of curvature, the thickness / distance are all millimeters (mm). The image light from the emitting part F sequentially passes through each element in the order of No. 24 to No. 1 and is finally projected to the receiving part J.

[0099] Table 3

[0100]

[0101]

[0102] In the present example, the surfaces of the first lens E1, the second lens E2, the third lens E3, and the fourth lens E4 are all aspherical surfaces, and the surface shape of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0103]

[0104] wherein x is the sag 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 inverse of the radius of curvature R in Table 3 above), k is the conic coefficient, and Ai is the correction coefficient of the i-th order of the aspherical surface. Table 4 shows the high-order term coefficients A4, A6, A8, A10, A12, A14, A16 of the aspherical surface of each lens that can be used in Example 1.

[0105] Table 4

[0106] Face number A4 A6 A8 A10 A12 A14 A16 S1 -8.78E-06 4.04E-08 -2.61E-11 4.27E-13 -1.95E-15 -1.20E-18 1.06E-20 S2 / S3 1.04E-05 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S4 -6.66E-08 9.29E-09 1.73E-10 1.01E-13 0.00E+00 0.00E+00 0.00E+00 S5 5.14E-06 -8.54E-09 4.07E-11 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S6 / S7 -4.39E-07 -4.08E-12 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S8 -4.00E-06 -3.58E-09 6.09E-13 6.35E-14 1.91E-17 -7.94E-19 1.04E-21

[0107] Example 2

[0108] Figure 4 shows a structural schematic diagram of the optical imaging system of Example 2 of the present application. As shown in FIG. 2, the optical imaging system of Example 2 comprises an emitting part F, an imaging part C, and a receiving part J. Figure 4As shown, the optical imaging system includes a lens barrel P0, an imaging part C and a spacer element group arranged in the lens barrel P0, a receiving part J (not shown) located at the first side of the lens barrel P0, and an emitting part F (not shown) located at the second side of the lens barrel P0.

[0109] The imaging part C sequentially includes, along the optical axis from the first side to the second side, a linear polarizer film LP, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, and a partially reflective layer BS. A stop STO (not shown) can be located at the first side of the first lens E1. In this embodiment, the first side refers to the side of the human eye, and the second side refers to the side of the display screen. Exemplarily, the receiving part J can be the human eye, and the emitting part F can be the display screen.

[0110] The imaging part C of the optical imaging system of this embodiment has the same structure as the imaging part C of the optical imaging system of Embodiment 1, and the basic parameters are shown in Tables 3 to 4, which will not be repeated here.

[0111] The difference between this embodiment and Embodiment 1 is that the structural sizes of at least part of the elements in the lens barrel P0 and the spacer element group are different.

[0112] Embodiment 3

[0113] Figure 5 The structural schematic diagram of the optical imaging system of Embodiment 3 of the present application is shown. As shown, Figure 5 The optical imaging system includes a lens barrel P0, an imaging part C and a spacer element group arranged in the lens barrel P0, a receiving part J (not shown) located at the first side of the lens barrel P0, and an emitting part F (not shown) located at the second side of the lens barrel P0.

[0114] The imaging part C sequentially includes, along the optical axis from the first side to the second side, a linear polarizer film LP, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, and a partially reflective layer BS. A stop STO (not shown) can be located at the first side of the first lens E1. In this embodiment, the first side refers to the side of the human eye, and the second side refers to the side of the display screen. Exemplarily, the receiving part J can be the human eye, and the emitting part F can be the display screen.

[0115] The imaging part C of the optical imaging system of this embodiment has the same structure as the imaging part C of the optical imaging system of Embodiment 1, and the basic parameters are shown in Tables 3 to 4, which will not be repeated here.

[0116] The difference between this embodiment and Embodiment 1 is that the structural sizes of at least part of the elements in the lens barrel P0 and the spacer element group are different.

[0117] Figure 6(A1) shows the axial chromatic aberration curves of the optical imaging lenses of Examples 1 to 3, which represent the deviation of light of different wavelengths from the focal point behind the lens. Figure 6 (B1) in FIG. 5 shows the astigmatism curves of the optical imaging lenses of Examples 1 to 3, which represent the meridional field curvature and the sagittal field curvature. Figure 6 (B1) in FIG. 1 shows the distortion curves of the optical imaging lenses of Examples 1 to 3, which represent the distortion values ​​corresponding to different field angles. Figure 6 It can be seen that the optical imaging lenses provided in Examples 1 to 3 can achieve good imaging quality.

[0118] Example 4

[0119] Figure 7 FIG. 1 shows a schematic structural diagram of an optical imaging system according to Example 1 of the present application. Figure 7 As shown, the optical imaging system includes a lens barrel P0, an imaging portion C and a spacer element group arranged in the lens barrel P0, a receiving portion J (not shown) located on a first side of the lens barrel P0, and a transmitting portion F (not shown) located on a second side of the lens barrel P0.

[0120] The imaging unit C includes, in order from the first side to the second side along the optical axis: a linear polarizer LP, a reflective polarizer RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, and a partially reflective layer BS. An aperture stop STO (not shown) may be located on the first side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. For example, the receiving unit J may be the human eye, and the transmitting unit F may be the display screen.

[0121] The first lens E1 has negative optical power, with its first side surface S1 being concave and its second side surface S2 being convex. The second lens E2 has positive optical power, with its first side surface S3 being concave and its second side surface S4 being convex. The third lens E3 has negative optical power, with its first side surface S5 being convex and its second side surface S6 being concave. The fourth lens E4 has positive optical power, with its first side surface S7 being convex and its second side surface S8 being convex. The second side surface S2 of the first lens E1 is cemented to the first side surface S3 of the second lens E2. The second side surface S6 of the third lens E3 is cemented to the first side surface S7 of the fourth lens E4. A quarter-wave plate QWP is attached to the first side surface S1 of the first lens E1, a reflective polarizer RP is attached to the first side surface of the quarter-wave plate QWP, and a linear polarizer film LP is attached to the first side surface of the reflective polarizer RP. A partially reflective layer BS is attached to the second side surface S8 of the fourth lens E4.

[0122] The spacer elements are located between the non-effective diameter regions of the lenses, and the set of spacer elements includes a second spacer element P2. The second spacer element P2 is located between the second lens E2 and the third lens E3, and a first side surface of the second spacer element P2 is at least partially in contact with a second side surface S4 of the second lens E2, and a second side surface of the second spacer element P2 is at least partially in contact with a first side surface S5 of the third lens E3.

[0123] In this example, the image light from the emitting part F enters the receiving part J after multiple times of reflection and refraction by the imaging part C. Specifically, the image light from the emitting part F sequentially passes through the partially reflective layer BS, the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter-wave plate QWP, and is reflected for the first time at the reflective polarizing element RP. The first-reflected light sequentially passes through the quarter-wave plate QWP, the first lens E1, the second lens E2, the third lens E3, and the fourth lens E4, and is reflected for the second time at the partially reflective layer BS. The second-reflected light sequentially passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter-wave plate QWP, the reflective polarizing element RP, the linear polarizing film LP, and the stop STO, and is finally projected to the receiving part J.

[0124] Table 5 shows a table of basic parameters of each element of the optical imaging system of Example 4, where the units of the radius of curvature, the thickness / distance are millimeters (mm). The image light from the emitting part F sequentially passes through each element in the order of sequence number 24 to sequence number 1, and is finally projected to the receiving part J.

[0125] Table 5

[0126]

[0127] In this example, the surfaces of the first lens E1, the second lens E2, the third lens E3, and the fourth lens E4 are all aspherical surfaces. Table 6 shows the high-order term coefficients A4, A6, A8, A10, A12, A14, A16 of the aspherical surfaces of each lens that can be used in Example 4.

[0128] Table 6

[0129]

[0130]

[0131] Example 5

[0132] Figure 8 A structure schematic diagram of the optical imaging system of Example 5 of the present application is shown. As shown in FIG. 5, the optical imaging system of Example 5 includes an emitting part F, an imaging part C, and a receiving part J. Figure 8As shown, the optical imaging system includes a lens barrel P0, an imaging part C and a spacer element group arranged in the lens barrel P0, a receiving part J (not shown) located at the first side of the lens barrel P0, and an emitting part F (not shown) located at the second side of the lens barrel P0.

[0133] The imaging part C sequentially includes, along the optical axis from the first side to the second side, a linear polarizer film LP, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, and a partially reflective layer BS. A stop STO (not shown) can be located at the first side of the first lens E1. In this embodiment, the first side refers to the side of the human eye, and the second side refers to the side of the display screen. Exemplarily, the receiving part J can be the human eye, and the emitting part F can be the display screen.

[0134] The imaging part C of the optical imaging system of this embodiment has the same structure as the imaging part C of the optical imaging system in Embodiment 4, and the basic parameters are shown in Tables 5 to 6, which are not repeated here.

[0135] The difference between this embodiment and Embodiment 4 is that the structural sizes of at least part of the elements in the lens barrel P0 and the spacer element group are different.

[0136] Embodiment 6

[0137] Figure 9 The structural schematic diagram of the optical imaging system of Embodiment 6 of the present application is shown. As shown, Figure 9 The optical imaging system includes a lens barrel P0, an imaging part C and a spacer element group arranged in the lens barrel P0, a receiving part J (not shown) located at the first side of the lens barrel P0, and an emitting part F (not shown) located at the second side of the lens barrel P0.

[0138] The imaging part C sequentially includes, along the optical axis from the first side to the second side, a linear polarizer film LP, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, and a partially reflective layer BS. A stop STO (not shown) can be located at the first side of the first lens E1. In this embodiment, the first side refers to the side of the human eye, and the second side refers to the side of the display screen. Exemplarily, the receiving part J can be the human eye, and the emitting part F can be the display screen.

[0139] The imaging part C of the optical imaging system of this embodiment has the same structure as the imaging part C of the optical imaging system in Embodiment 4, and the basic parameters are shown in Tables 5 to 6, which are not repeated here.

[0140] The difference between this embodiment and Embodiment 4 is that the structural sizes of at least part of the elements in the lens barrel P0 and the spacer element group are different.

[0141] Figure 10(A2) shows the axial chromatic aberration curves of the optical imaging lenses of Examples 4 to 6, which represent the deviation of light of different wavelengths from the focal point behind the lens. Figure 10 (B2) in FIG. 5 shows the astigmatism curves of the optical imaging lenses of Examples 4 to 6, which represent the meridional field curvature and the sagittal field curvature. Figure 10 (C2) in the figure shows the distortion curves of the optical imaging lenses of Examples 4 to 6, which represent the distortion values ​​corresponding to different field angles. Figure 10 It can be seen that the optical imaging lenses provided in Examples 4 to 6 can achieve good imaging quality.

[0142] Example 7

[0143] Figure 11 FIG. 1 shows a schematic structural diagram of an optical imaging system according to Example 7 of the present application. Figure 11 As shown, the optical imaging system includes a lens barrel P0, an imaging portion C and a spacer element group arranged in the lens barrel P0, a receiving portion J (not shown) located on a first side of the lens barrel P0, and a transmitting portion F (not shown) located on a second side of the lens barrel P0.

[0144] The imaging unit C includes, in order from the first side to the second side along the optical axis: a linear polarizer LP, a reflective polarizer RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, and a partially reflective layer BS. An aperture stop STO (not shown) may be located on the first side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. For example, the receiving unit J may be the human eye, and the transmitting unit F may be the display screen.

[0145] The first lens E1 has negative optical power, with its first side surface S1 being concave and its second side surface S2 being convex. The second lens E2 has negative optical power, with its first side surface S3 being concave and its second side surface S4 being convex. The third lens E3 has negative optical power, with its first side surface S5 being convex and its second side surface S6 being concave. The fourth lens E4 has positive optical power, with its first side surface S7 being convex and its second side surface S8 being convex. The second side surface S2 of the first lens E1 is cemented to the first side surface S3 of the second lens E2. The second side surface S6 of the third lens E3 is cemented to the first side surface S7 of the fourth lens E4. A quarter-wave plate QWP is attached to the first side surface S1 of the first lens E1, a reflective polarizer RP is attached to the first side surface of the quarter-wave plate QWP, and a linear polarizer film LP is attached to the first side surface of the reflective polarizer RP. A partially reflective layer BS is attached to the second side surface S8 of the fourth lens E4.

[0146] The spacer elements are located between the non-effective diameter regions of the lenses, and the set of spacer elements includes a second spacer element P2. The second spacer element P2 is located between the second lens E2 and the third lens E3, and a first side surface of the second spacer element P2 is at least partially in contact with a second side surface S4 of the second lens E2, and a second side surface of the second spacer element P2 is at least partially in contact with a first side surface S5 of the third lens E3.

[0147] In the present example, the image light from the emitting portion F enters the receiving portion J after multiple times of fold reflection by the imaging portion C. Specifically, the image light from the emitting portion F sequentially passes through the partially reflective layer BS, the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter-wave plate QWP, and is reflected for the first time at the reflective polarizing element RP. The first-reflected light sequentially passes through the quarter-wave plate QWP, the first lens E1, the second lens E2, the third lens E3, and the fourth lens E4, and is reflected for the second time at the partially reflective layer BS. The second-reflected light sequentially passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter-wave plate QWP, the reflective polarizing element RP, the linear polarizing film LP, and the stop STO, and is finally projected to the receiving portion J.

[0148] Table 7 shows a table of basic parameters of the elements of the optical imaging system of Example 7, wherein the units of the radius of curvature, the thickness / distance are millimeters (mm). The image light from the emitting portion F sequentially passes through the elements in the order of the sequence number 24 to the sequence number 1, and is finally projected to the receiving portion J.

[0149] Table 7

[0150]

[0151] In the present example, the surfaces of the first lens E1, the second lens E2, the third lens E3, and the fourth lens E4 are aspherical surfaces. Table 8 shows the high-order term coefficients A4, A6, A8, A10, A12, A14, A16 of the aspherical surfaces of the lenses that can be used in Example 7.

[0152] Table 8

[0153]

[0154]

[0155] Example 8

[0156] Figure 12 A structure schematic diagram of the optical imaging system of Example 8 of the present application is shown. As shown in FIG. 8, the optical imaging system of Example 8 includes an emitting portion F, an imaging portion C, and a receiving portion J. Figure 12As shown, the optical imaging system includes a lens barrel P0, an imaging part C and a spacer element group arranged in the lens barrel P0, a receiving part J (not shown) located at the first side of the lens barrel P0, and an emitting part F (not shown) located at the second side of the lens barrel P0.

[0157] The imaging part C sequentially includes, along the optical axis from the first side to the second side, a linear polarizer film LP, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, and a partially reflective layer BS. A stop STO (not shown) can be located at the first side of the first lens E1. In this embodiment, the first side refers to the side of the human eye, and the second side refers to the side of the display screen. Exemplarily, the receiving part J can be the human eye, and the emitting part F can be the display screen.

[0158] The imaging part C of the optical imaging system of this embodiment has the same structure as the imaging part C of the optical imaging system in Embodiment 7, and the basic parameters are shown in Tables 7 to 8, which are not repeated here.

[0159] The difference between this embodiment and Embodiment 7 is that the structural sizes of at least part of the elements in the lens barrel P0 and the spacer element group are different.

[0160] Embodiment 9

[0161] Figure 13 The structural schematic diagram of the optical imaging system of Embodiment 9 of the present application is shown. As shown, Figure 13 The optical imaging system includes a lens barrel P0, an imaging part C and a spacer element group arranged in the lens barrel P0, a receiving part J (not shown) located at the first side of the lens barrel P0, and an emitting part F (not shown) located at the second side of the lens barrel P0.

[0162] The imaging part C sequentially includes, along the optical axis from the first side to the second side, a linear polarizer film LP, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, and a partially reflective layer BS. A stop STO (not shown) can be located at the first side of the first lens E1. In this embodiment, the first side refers to the side of the human eye, and the second side refers to the side of the display screen. Exemplarily, the receiving part J can be the human eye, and the emitting part F can be the display screen.

[0163] The imaging part C of the optical imaging system of this embodiment has the same structure as the imaging part C of the optical imaging system in Embodiment 7, and the basic parameters are shown in Tables 7 to 8, which are not repeated here.

[0164] The difference between this embodiment and Embodiment 7 is that the structural sizes of at least part of the elements in the lens barrel P0 and the spacer element group are different.

[0165] Figure 14(A3) in FIG. 12 shows the on-axis chromatic aberration curves of the optical imaging lenses of Embodiments 7-9, which represent the convergence point deviation of light rays of different wavelengths after passing through the lenses. Figure 14 (B3) in FIG. 13 shows the astigmatism curves of the optical imaging lenses of Embodiments 7-9, which represent the meridional image surface curvature and sagittal image surface curvature. Figure 14 (C3) in FIG. 14 shows the distortion curves of the optical imaging lenses of Embodiments 7-9, which represent the distortion size values corresponding to different field angles. According to Figure 14 It can be known that the optical imaging lenses provided by Embodiments 7-9 can achieve good imaging quality.

[0166] Table 9 gives the parameter values of f1, f2, f3, f4 of each of Embodiments 1-9, and the units of the parameters listed in Table 9 are all millimeters (mm).

[0167] Table 9

[0168]

[0169] Table 10 gives the values of the parameters of the lens barrel P0 and at least part of the elements in the spacer element group in each of Embodiments 1-9. Among them, part of the parameters can be measured according to the labeling method shown in Figure 1 and the units of the parameters listed in Table 10 are all millimeters (mm).

[0170] Table 10

[0171] Parameter / Embodiment 1 2 3 4 5 6 7 8 9 d0s 33.536 33.536 33.102 33.318 33.318 34.450 35.465 35.465 35.057 d0m 41.783 41.783 41.783 42.869 42.869 42.720 46.041 46.041 46.041 D0s 41.264 41.264 39.000 39.818 39.818 39.818 42.990 42.990 42.990 D0m 44.579 44.579 44.579 45.160 45.160 45.011 48.332 48.332 48.332 d2s 35.288 35.492 35.727 36.717 37.184 36.717 37.726 38.499 37.726 d2m 36.616 36.540 36.616 37.950 38.164 37.950 41.601 41.010 41.284 D2m 37.913 38.136 37.913 39.347 39.456 39.347 43.010 43.010 42.827 CP2 1.741 1.741 1.836 2.487 2.400 2.487 2.675 2.675 2.675 EP02 5.496 5.496 5.132 6.356 6.356 6.356 7.502 7.502 7.502

[0172] In summary, the optical imaging systems in Embodiments 1-9 satisfy the relationships shown in Table 11.

[0173] Table 11

[0174] Conditional / Embodiment 1 2 3 4 5 6 7 8 9 R1 / (D0s-d0s) -6.26 -6.26 -8.20 -7.56 -7.56 -9.15 -7.08 -7.08 -6.71 (CT1+CT2) / EP02 0.83 0.83 0.89 0.63 0.63 0.63 0.47 0.47 0.47 T23 / CP2 0.86 0.86 0.82 0.60 0.63 0.60 0.56 0.56 0.56 R8 / (D0m-d0m) -14.62 -14.62 -14.62 -19.88 -19.88 -19.88 -18.26 -18.26 -18.26 |f2 / d2s| 4.50 4.47 4.44 4.11 4.06 4.11 5.12 5.02 5.12 (CT3+CT4) / CP2 3.45 3.45 3.27 2.63 2.72 2.63 2.89 2.89 2.89 R4 / d2s -1.32 -1.31 -1.30 -1.52 -1.50 -1.52 -5.05 -4.95 -5.05 f1*(dlp+drp+dqwp) -29.78 -29.78 -29.78 -21.64 -21.64 -21.64 -58.64 -58.64 -58.64 |R7 / d2m| 1.23 1.23 1.23 1.91 1.90 1.91 1.37 1.39 1.38 |f3 / D2m| 5.93 5.90 5.93 3.58 3.57 3.58 3.16 3.16 3.17

[0175] The present application also provides an optical device, which can be a separate projection device such as a projector, or a projection module integrated on a mobile electronic device such as a virtual reality device or an augmented reality device. The optical device is equipped with the optical imaging system described above.

[0176] The above description is only the preferred embodiment of the present application and the explanation of the technical principles. It should be understood by those skilled in the art that the scope of the disclosure of the present application is not limited to the technical scheme composed of the specific combination of the above technical features, and should also cover other technical schemes formed by the combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical scheme formed by replacing the above features with the technical features disclosed in the present application (but not limited to) having similar functions.

Claims

1. An optical imaging system, characterized in that include: Imaging department, including: a first lens, a second lens, a third lens, and a fourth lens having optical power arranged in sequence from the first side to the second side along the optical axis, wherein the first lens is cemented with the second lens, the third lens is cemented with the fourth lens, and the number of lenses having optical power in the imaging portion is four; a quarter-wave plate attached to the first side surface of the first lens; a reflective polarizing element, attached to the first side surface of the quarter-wave plate; a linear polarizing film attached to the first side surface of the reflective polarizing element; and a partially reflective layer, attached to the second side surface of the fourth lens; a spacer element set comprising at least one spacer element; a lens barrel accommodating the imaging portion and the spacer element group; and The optical imaging system satisfies: -9.15≤R1 / (D0s-d0s)≤-6.26; Wherein, R1 is the curvature radius of the first side surface of the first lens, D0s is the outer diameter of the first side end surface of the lens barrel; d0s is the inner diameter of the first side end surface of the lens barrel.

2. The optical imaging system according to claim 1, wherein: The spacer element group includes a second spacer element, the second spacer element is located between the second lens and the third lens and contacts the second side surface of the second lens; The optical imaging system satisfies the following: 0.47≤(CT1+CT2) / EP02≤0.89, where CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, and EP02 is the distance between the first side end surface of the lens barrel and the first side surface of the second spacer element along the optical axis.

3. The optical imaging system according to claim 1, wherein: The spacer element group includes a second spacer element, the second spacer element is located between the second lens and the third lens and contacts the second side surface of the second lens; The optical imaging system satisfies: 0.56≤T23 / CP2≤0.86, wherein T23 is the distance from the second side surface of the second lens to the first side surface of the third lens on the optical axis, and CP2 is the maximum thickness of the second spacer element.

4. The optical imaging system according to claim 1, wherein: The spacer element group includes a second spacer element, the second spacer element is located between the second lens and the third lens and contacts the second side surface of the second lens; The optical imaging system satisfies the following: 2.63≤(CT3+CT4) / CP2≤3.45, where CT3 is the center thickness of the third lens on the optical axis, CT4 is the center thickness of the fourth lens on the optical axis, and CP2 is the maximum thickness of the second spacer element.

5. The optical imaging system according to claim 1, wherein: The spacer element group includes a second spacer element, the second spacer element is located between the second lens and the third lens and contacts the second side surface of the second lens; The optical imaging system satisfies the following: 4.06≤|f2 / d2s|≤5.12, wherein f2 is the effective focal length of the second lens, and d2s is the inner diameter of the first side surface of the second spacer element.

6. The optical imaging system according to claim 1, wherein: The spacer element group includes a second spacer element, the second spacer element is located between the second lens and the third lens and contacts the second side surface of the second lens; The optical imaging system satisfies the following: -5.05≤R4 / d2s≤-1.3, wherein R4 is the curvature radius of the second side surface of the second lens, and d2s is the inner diameter of the first side surface of the second spacer element.

7. The optical imaging system according to claim 1, wherein: The spacer element group includes a second spacer element, the second spacer element is located between the second lens and the third lens and contacts the second side surface of the second lens; The optical imaging system satisfies the following: 1.23≤|R7 / d2m|≤1.91, wherein R7 is the curvature radius of the first side surface of the fourth lens, and d2m is the inner diameter of the second side surface of the second spacer element.

8. The optical imaging system according to claim 1, wherein: The spacer element group includes a second spacer element, the second spacer element is located between the second lens and the third lens and contacts the second side surface of the second lens; The optical imaging system satisfies the following condition: 3.16≤|f3 / D2m|≤5.93, wherein f3 is the effective focal length of the third lens, and D2m is the outer diameter of the second side surface of the second spacer element.

9. The optical imaging system according to any one of claims 1 to 8, characterized in that: The optical imaging system satisfies: -19.88≤R8 / (D0m-d0m)≤-14.62, wherein R8 is the curvature radius of the second side surface of the fourth lens, D0m is the outer diameter of the second side end surface of the lens barrel, and d0m is the inner diameter of the second side end surface of the lens barrel.

10. The optical imaging system according to any one of claims 1 to 8, characterized in that: The optical imaging system meets the following requirements: -58.64mm 2 ≤f1*(dlp+drp+dqwp)≤-21.61mm 2 , wherein f1 is the effective focal length of the first lens, dlp is the center thickness of the linear polarizing film on the optical axis, drp is the center thickness of the reflective polarizing element on the optical axis, and dqwp is the center thickness of the quarter-wave plate on the optical axis.

11. The optical imaging system according to any one of claims 1 to 8, characterized in that: The first side surface of the first lens is a concave surface; The second side surface of the second lens is a convex surface; The second side surface of the fourth lens is a convex surface.

12. The optical imaging system according to any one of claims 1 to 8, characterized in that: The first lens has negative optical power; The second lens has positive or negative optical power; The third lens has positive or negative optical power; The fourth lens has positive refractive power.

Images