Optical image capturing system

Abstract

The invention 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, and in particular to an optical imaging system. Background Art

[0002] Optical imaging systems of virtual reality devices or augmented reality devices are mainly divided into three types: optical imaging systems using aspherical lenses, optical imaging systems using Fresnel lenses, and catadioptric optical imaging systems. Among them, the catadioptric optical imaging system is a major innovation of the optical imaging system itself, and it reserves space for the overall design of virtual reality devices or augmented reality devices, 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 bending the optical path, thereby moving the center of gravity of the virtual reality device or augmented reality device backward, which helps to improve the user experience. However, from the user experience point of view, its weight and thickness are still not perfect, and because the lens used is larger than the traditional lens, its molding difficulty is higher. The lens volume of the catadioptric optical imaging system is large, and in order to compress the total length of the system, when the first lens and the second lens are glued together, it is easy to reduce the assembly stability between the lens and the lens barrel. Summary of the invention

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

[0005] According to an exemplary embodiment of the present application, the spacer element group includes a second spacer element, which 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: 0.47≤(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 along the optical axis.

[0006] According to an exemplary embodiment of the present application, the spacer element group includes a second spacer element, which 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.

[0007] According to an exemplary embodiment of the present application, the spacer element group includes a second spacer element, which 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: 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, which 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: 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, which 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: -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, which 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: 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 an exemplary embodiment of the present application, the spacer element group includes a second spacer element, which 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: 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 an exemplary embodiment of the present application, the optical imaging system satisfies: -19.88≤R8 / (D0m-d0m)≤-14.62, wherein R8 is the radius of curvature 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 an exemplary embodiment of the present application, the optical imaging system satisfies: -58.64 mm 2 ≤f1*(dlp+drp+dqwp)≤-21.61mm 2 , where 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.

[0014] According to an exemplary embodiment 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 an exemplary embodiment of the present application, 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; and the fourth lens has positive optical power.

[0016] The optical imaging system provided by the present application, by providing a reflective polarizing element, a quarter-wave plate, a partial reflective layer, etc., enables light to be refracted multiple times in the imaging part, and can fold the optical path while ensuring the imaging quality, thereby effectively shortening the main body length of the optical imaging system. By controlling the range of the conditional formula R1 / (D0s-d0s), the width of the lens barrel used for supporting is adjusted to an appropriate range, thereby constraining the shape of the first lens, thereby ensuring that the optical imaging system can be well focused into the human eye and solving the problem of poor assembly stability between the first lens and the lens barrel when the second lens is glued together. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings, in which:

[0018] Figure 1 The schematic diagram shows the structural arrangement and some parameters of an optical imaging system of the present application;

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

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

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

[0022] Figure 5 A schematic diagram showing the structure of the optical imaging system of Example 3 of the present application is shown.

[0023] Figure 6 The axial chromatic aberration curve (A1), the astigmatism curve (B1), and the distortion curve (C1) of the optical imaging system of Examples 1 to 3 of the present application are shown;

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

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

[0026] Fig. 9 A schematic structural diagram of an optical imaging system according to Embodiment 6 of the present application is shown;

[0027] Fig.10 The axial chromatic aberration curve (A2), the astigmatism curve (B2), and the distortion curve (C2) of the optical imaging system of Examples 4 to 6 of the present application are shown;

[0028] Fig.11 A schematic structural diagram of an optical imaging system according to Embodiment 7 of the present application is shown;

[0029] Fig.12 A schematic structural diagram of an optical imaging system according to Embodiment 8 of the present application is shown;

[0030] Fig.13 A schematic structural diagram of an optical imaging system according to Embodiment 9 of the present application is shown;

[0031] Fig.14 The axial chromatic aberration curve (A3), astigmatism curve (B3), and distortion curve (C3) of the optical imaging system of Examples 7 to 9 of the present application are shown. DETAILED DESCRIPTION

[0032] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and do not limit the scope of the present application in any way. Throughout the specification, the same figure numerals refer to the same elements.

[0033] It should be noted that in this specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

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

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

[0036] The optical imaging system of the exemplary embodiment of the present application can be simulated by software and / or tools such as ZEMAX and CODEV. Alternatively, the optical imaging system can be simulated by CODEV software. In the process of simulation using the above software and / or tools, the surface shape of each lens can be appropriately adjusted according to the surface shape model of the software and / or tool used.

[0037] It should also be understood that the terms "including" and / or "having", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when describing the embodiments of the present application, the term "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0038] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as those commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0039] It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The following examples only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for those of ordinary skill in the art, without departing from the concept of the present application, several variations and improvements can also be made, which 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 embodiments.

[0041] Figure 1 The structural arrangement and partial parameter diagram of an optical imaging system of the present application are shown as an example to facilitate a better understanding of the present application. Figure 1 As shown, D0s is the outer diameter of the first side end face of the lens barrel, d0s is the inner diameter of the first side end face of the lens barrel, D2s is the outer diameter of the first side face of the second spacing element, d2s is the inner diameter of the first side face of the second spacing element, d2m is the inner diameter of the second side face of the second spacing element, D2m is the outer diameter of the second side face of the second spacing element, d0m is the inner diameter of the second side end face of the lens barrel, D0m is the outer diameter of the second side end face of the lens barrel, EP02 is the distance between the first side end face of the lens barrel and the first side face of the second spacing element along the optical axis, CP2 is the maximum thickness of the second spacing element, and L is the distance from the first side end face to the second side end face of the lens barrel along the optical axis.

[0042] Figure 2 FIG. 2 shows a schematic diagram of the structure arrangement of an optical imaging system of the present application. Figure 2 As shown, 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 on the second side of the system and can emit image light, for example, it can be a display screen, and the imaging part C can refract the image light emitted by the transmitting part F for multiple times, and finally project it to the receiving part J, and the receiving part J is located on the first side of the system, for example, it can be a human eye.

[0043] refer to Figure 2 , Figures 3 to 5 , Figures 7 to 9 , Figures 11 to 13According to a first aspect of the present application, an optical imaging system is provided. An imaging portion of the optical imaging system includes a first lens, a second lens, a third lens, and a fourth lens having optical focal lengths, which are arranged in sequence from a first side to a second side along an optical axis.

[0044] In an exemplary embodiment, the number of lenses having optical power in the imaging portion is four. Each lens has at least one first side surface facing the first side and one 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, that is, the second side surface of the first lens is cemented to 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 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 power and can converge light. When used together with a lens having negative power, the aberration of the entire optical imaging system can be effectively adjusted to improve the imaging quality.

[0050] In an exemplary embodiment, the third lens and the fourth lens form a cemented lens, that is, the second side surface of the third lens is cemented with the first side surface of the fourth lens. Exemplarily, 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 a concave surface, the second side surface of the second lens is a convex surface, and the two side surfaces of the fourth lens are convex surfaces. The first side surface of the first lens is a concave surface, which can increase the field of view angle, thereby increasing the visual range. The second side surface of the second lens and the second side surface of the fourth lens are convex surfaces, which can make the light emitted to the image plane as convergent as possible while keeping the thickness of the third lens small, and the image height is small, 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 may have a separation distance on the optical axis, and the separation distance may be an air separation.

[0053] In an exemplary embodiment, each lens has an effective diameter region through which light can pass and a non-effective diameter region surrounding the effective diameter region through which light cannot pass. Figure 2 As shown, the center point Q1 of the first side surface of the first lens is the intersection of the first side surface of the first lens and the optical axis, and the edge point Q2 of the first side surface of the first lens is the critical point between the effective diameter area and the ineffective diameter area of ​​the first side surface of the first lens.

[0054] refer to Figures 3 to 5 , Figures 7 to 9 , Figures 11 to 13 The imaging part of the optical imaging system of the present application also includes a quarter-wave plate, a reflective polarizing element, a linear polarization film and a partial reflective layer.

[0055] In an exemplary embodiment, a linear polarizing film, a reflective polarizing element and a quarter wave plate are sequentially attached to the first side surface of the first lens from the first side to the second side, that is, 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, and the linear polarizing film is attached to the first side surface of the reflective polarizing element. Among them, the quarter wave plate is used to change the polarization state of light, for example, converting circularly polarized light into linearly polarized light, or converting linearly polarized light into circularly polarized light. Circularly polarized light may include right-handed circularly polarized light or left-handed circularly polarized light. Linearly polarized light may 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 may reflect S linearly polarized light and transmit P linearly polarized light, or the reflective polarizing element may reflect P linearly polarized light and transmit S linearly polarized light.

[0056] In an exemplary embodiment, the partial reflective layer is attached to the second side surface of the fourth lens. Exemplarily, the partial reflective layer can have a semi-transmissive and semi-reflective effect on the light. By arranging the partial reflective layer on the second side surface of the fourth lens and combining the reflective polarizing element and the quarter-wave plate, the light can be refracted multiple times, effectively reducing the main body length of the optical imaging system.

[0057] In an exemplary embodiment, the optical imaging system may further include an aperture, which is conducive to converging the light entering the optical imaging system, reducing the maximum aperture of the system, and reducing the assembly sensitivity of the system, so as to further improve the imaging quality of the system. It should be noted that the aperture can be set between the lenses or at one side according to actual needs. Exemplarily, the aperture is set 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 reflective layer, etc., the light can be refracted multiple times in the imaging part, and the optical path can be folded under the premise of ensuring the imaging quality, which effectively shortens the main body length of the optical imaging system. Exemplarily, the image light from the transmitting part passes through the partial reflective layer, the fourth lens, the third lens, the second lens, the first lens, 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 then is reflected for the second time at the partial reflective 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 polarization film to the aperture and is finally projected to the receiving part.

[0059] In an exemplary embodiment, the optical imaging system further includes a spacer element group, and the spacer element group may 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 intercept redundant refractive and reflective light paths, reduce stray light and ghosting, and improve imaging quality.

[0060] In an exemplary embodiment, the spacer element group includes a second spacer element located between the second lens and the third lens, and a first side of the second spacer element at least partially contacts a second side of the second lens, and a second side of the second spacer element at least partially contacts a first side of the third lens.

[0061] In an exemplary embodiment, the optical imaging system further includes a lens barrel. The imaging portion 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 a 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 peripheral surface of at least one lens in the imaging unit may have a trimmed portion and a non-trimmed portion, and the outer diameter of the trimmed portion of the lens may be smaller than the outer diameter of the non-trimmed portion of the lens. When the outer peripheral surface of the lens has a trimmed portion, the outer diameter of the lens generally refers to the outer diameter of the non-trimmed portion of the lens. For example, the outer diameter of the first side surface of the lens refers to the outer diameter of the portion of the non-trimmed 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 portion of the non-trimmed portion of the lens closest to the second side.

[0063] In an exemplary embodiment, the outer circumferential surface of at least one spacer element in the spacer element group may have a trimmed portion and a non-trimmed portion, and the outer diameter of the trimmed portion of the spacer element may be smaller than the outer diameter of the non-trimmed portion of the spacer element. When the outer circumferential surface of the spacer element has a trimmed portion, the outer diameter of the spacer element generally refers to the outer diameter of the non-trimmed 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-trimmed portion of the spacer element closest to the first side, and the outer diameter of the second side surface of the spacer element refers to the outer diameter of the portion of the non-trimmed portion of the spacer element closest to the second side.

[0064] In an exemplary embodiment, the optical imaging system of the present application may further include a filter as required, and the filter may filter light with different wavelengths. Exemplarily, the filter may be disposed between the partial reflective layer and the emitting portion.

[0065] In an exemplary 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; d0s is the inner diameter of the first side end surface of the lens barrel. By controlling the above conditions, the width of the lens barrel for supporting can be adjusted to an appropriate range, the shape of the first lens is constrained, and the problem of poor assembly stability between the first lens and the lens barrel when the second lens is glued together is solved while ensuring that the optical imaging system can be well focused on the human eye.

[0066] Table 1 is a structural sensitivity analysis table of the surface shape change 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 surface shape change of the first side surface of the first lens in the optical imaging system. Among them, system 1 satisfies R1 / (D0s-d0s)=-7.63; system 2 satisfies R1 / (D0s-d0s)=-3.26; system 3 satisfies R1 / (D0s-d0s)=-12.85.

[0067] In Table 1, surface S1 is the first side surface of the first lens. △S1PV (i.e., structural sensitivity) is the amount of change in the surface shape of the first side surface of the first lens. Under stress, the structure of the non-effective diameter area of ​​the first side surface of the first lens will deform, and the center point and edge point of the first side surface of the first lens will be displaced, resulting in a change in surface shape accuracy. Among them, △S1PV is the difference between the displacement of the center point and the displacement of the edge point. It should be understood that the smaller the △S1PV, the better the structural sensitivity. Figure 2 As shown, 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.

[0068] In Table 2, 0.8S.Peak may be the S-curve peak value of the MTF curve under the field of view of 0.8, 0.8M.Peak may be the M-curve peak value of the MTF curve under the field of view of 0.8, "S" is the sagittal curve, and "M" is the meridian curve. When △S1PV changes, 0.8S.Peak and / or 0.8M.Peak will change with the change of △S1PV, and the change of 0.8S.Peak and / or 0.8M.Peak may be the optical sensitivity. Among them, S+ refers to an increase of 1μm in △S1PV, and S- refers to a decrease of 1μm in △S1PV. The comprehensive sensitivity may 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, the better the optical sensitivity; the smaller the absolute value of the comprehensive sensitivity, the better the comprehensive sensitivity.

[0069] Table 1

[0070]

[0071] Table 2

[0072]

[0073] The structural sensitivity indicates the amount of change in the surface shape of the first side surface 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 parts of the first side surface of the first lens of System 1, System 2 and System 3 (i.e., the non-effective diameter area) are respectively subjected to the same external force. Under the influence of stress, the center point and edge point of the first side surface of the first lens are displaced. As shown in Table 1, through simulation, the structural sensitivities of System 1, System 2 and System 3 are 1.57E-02μm, 8.64E-01μm and 7.75E+00μm, respectively. It can be seen that the structural sensitivity of System 1 is smaller, that is, the displacement is smaller, the structural sensitivity of System 1 is better, and the structural sensitivities of System 2 and System 3 are poorer.

[0074] Optical sensitivity refers to the change in the MTF peak value of the system when the displacement of the system is constant. 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, △S1PV is a positive value, so the optical sensitivity takes the sensitivity value of S+. As shown in Table 2, through simulation, when △S1PV increases by 1μm, the changes in 0.8S.Peak of System 1, System 2 and System 3 are -0.73%, -0.93% and -0.79% respectively, and the changes in 0.8M.Peak are -0.59%, -0.68% and -0.83% respectively. It can be seen that the MTF peak of System 1 is less affected by deformation, the optical sensitivity of System 1 is better, and the optical sensitivity of System 2 and System 3 is poor.

[0075] The comprehensive sensitivity indicates the influence of deformation on the MTF peak of the system. As shown in Table 2, the comprehensive sensitivities of the S direction of System 1, System 2 and System 3 are -1.15E-02μm, -8.04E-01μm and -6.12E+00μm, respectively, and the comprehensive sensitivities of the M direction are -9.26E-03μm, -5.88E-01μm and -6.43E+00μm, respectively. It can be seen that the force deformation of System 1 is small, and the influence of deformation on the MTF peak is small. The comprehensive sensitivity of System 1 is small, and the assembly stability is good. The assembly stability of System 2 and System 3 is poor.

[0076] Combined with the above analysis, it can be seen that by making the optical imaging system satisfy -9.15≤R1 / (D0s-d0s)≤-6.26, it is possible to ensure that the first lens has a smaller deformation amount, reduce the structural sensitivity and optical sensitivity of the optical imaging system, thereby reducing the comprehensive sensitivity of the optical imaging system and improving the assembly stability of the optical imaging system. The assembly stability of the optical imaging system outside the above conditional range is poor.

[0077] 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 contacts 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 along the optical axis. Since more stray light will be generated when the thickness of the second spacer element is large, controlling the above conditions is conducive to reducing the reflection of excess light, thereby improving stray light and enhancing the imaging quality of the system. At the same time, by controlling the ratio of the middle thickness to the edge thickness of the first lens and the second lens within a certain range, it is conducive to the processing, molding and gluing of the first lens and the second lens.

[0078] 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 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. By controlling the above conditions, on the one hand, the ratio of the middle thickness to the edge thickness of the second lens and the third lens can be limited within a certain range, which is beneficial to the molding of the second lens and the third lens, and is also beneficial 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 from the second side surface of the second lens to 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 can be improved.

[0079] 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 contacts 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. By controlling the above conditions, it is beneficial to assemble the third lens and the fourth lens, reduce the deformation of the third lens, the fourth lens and the spacer element after assembly, and improve the assembly stability of the system.

[0080] In an exemplary embodiment, the spacer element group includes a second spacer element, which 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: 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, it can generate positive spherical aberration and balance it 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 inner diameter of the first side surface of the second spacer element, on the basis of ensuring its bearing function, it is beneficial to improve the machinability of the second spacer element.

[0081] In an exemplary embodiment, the spacer element group includes a second spacer element, which 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: -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. By controlling the above conditions, 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 the assembly; on the other hand, the refractive properties of the second spacer element and the second lens can be matched to prevent the risk of stray light or the reduction of light efficiency caused by the deviation of useless light and the blocking of useful light.

[0082] In an exemplary embodiment, the spacer element group includes a second spacer element, which 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: 1.23≤|R7 / d2m|≤1.91, where 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. By controlling the above conditions, 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 the assembly; on the other hand, the stray light generated by the light path reflected by the small inclined surface from the effective diameter edge mechanism of the first side surface of the fourth lens to the inside of the imaging unit can be blocked.

[0083] In an exemplary embodiment, the spacer element group includes a second spacer element, which 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: 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. By controlling the effective focal length of the third lens within a certain range, it can generate positive spherical aberration and balance it 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, on the basis of ensuring its bearing function, it is beneficial to improve the machinability of the second spacer element.

[0084] In an exemplary embodiment, the optical imaging system satisfies: -19.88≤R8 / (D0m-d0m)≤-14.62, wherein R8 is the radius of curvature 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 conditions, 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 the assembly, and on the other hand, it can ensure that the refractive properties of the lens barrel and the lens are matched to light; by controlling the inner and outer diameters of the second side end surface of the lens barrel, not only can the feasibility of lens barrel molding be guaranteed, but also the risk of stray light or reduction of light efficiency caused by the deflection of useless light and the blocking of useful light can be prevented.

[0085] In an exemplary embodiment, the optical imaging system satisfies: -58.64 mm 2 ≤f1*(dlp+drp+dqwp)≤-21.61mm 2 , where 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. By controlling the above conditions, it is possible to achieve a reasonable distribution of optical power, ensure that the thickness of the first lens is small, and facilitate the miniaturization of the system.

[0086] In an 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 an aspherical surface. The characteristic of an aspherical lens is that the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. After adopting an aspherical lens, the aberration occurring during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0087] The second aspect of the present application provides an optical imaging system, which includes a lens barrel and an imaging part and a spacer element group contained in the lens barrel, wherein the imaging part includes a first lens with optical focal power, a second lens with optical focal power, a third lens with optical focal power, a fourth lens with optical focal power, a quarter-wave plate, a reflective polarizing element, a linear polarizing film and a partial reflective layer, wherein the first lens, the second lens, the third lens and the fourth lens are arranged in sequence from the first side to the second side along the optical axis, the first lens is glued to the second lens, the third lens is glued to the fourth lens, the quarter-wave plate is attached to the first side surface of the first lens, and the reflective polarizing element is arranged in sequence from the first side to the second side along the optical axis. The transmissive 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 reflective layer is attached to the second side surface of the fourth lens; the number of lenses with optical focal length in the imaging portion is four; the spacer element group includes at least one spacer element; and 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 along the optical axis.

[0088] The present application sets a reflective polarizing element, a quarter-wave plate, a partial reflective layer, etc., so that the light can be refracted multiple times in the imaging part, and the optical path can be folded under the premise of ensuring the imaging quality, thereby effectively shortening the main body length of the optical imaging system. By controlling (CT1+CT2) / EP02, it is helpful to reduce the reflection of excess light, thereby improving stray light and enhancing the imaging quality of the system. At the same time, by controlling the ratio of the middle thickness to the edge thickness of the first lens and the second lens within a certain range, it is beneficial to the processing, molding and gluing of the first lens and the second lens.

[0089] Those skilled in the art should understand that, without departing from the technical solution claimed in the present application, the number of lenses and other elements constituting the optical imaging system can be changed to obtain the various results and advantages described in this specification.

[0090] The following further describes a specific embodiment of the optical imaging system applicable to the above-mentioned embodiment with reference to the accompanying drawings. Figures 3 to 6 Describe the optical imaging system according to Embodiments 1 to 3 of the present application; refer to Figures 7 to 10 Describe the optical imaging system according to Embodiment 4 to Embodiment 6 of the present application; refer to Figures 11 to 14 Describe the optical imaging system according to Embodiment 7 to Embodiment 9 of the present application.

[0091] Example 1

[0092] Figure 3 FIG. 1 is a schematic diagram showing the structure of an optical imaging system according to Embodiment 1 of the present application. Figure 3As shown, the optical imaging system includes a lens barrel P0, an imaging portion C and a spacing 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.

[0093] The imaging part C includes, from the first side to the second side along the optical axis, a linear polarization 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 partial reflection layer BS. The aperture 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. Exemplarily, the receiving part J may be a human eye, and the transmitting part F may be a display screen.

[0094] The first lens E1 has negative power, and its first side surface S1 is concave, and its second side surface S2 is convex. The second lens E2 has positive power, and its first side surface S3 is concave, and its second side surface S4 is convex. The third lens E3 has positive power, and its first side surface S5 is concave, and its second side surface S6 is convex. The fourth lens E4 has positive power, and its first side surface S7 is concave, and its second side surface S8 is convex. The second side surface S2 of the first lens E1 is glued to the first side surface S3 of the second lens E2. The second side surface S6 of the third lens E3 is glued 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 polarizer RP is attached to the first side surface of the quarter wave plate QWP, and the linear polarization film LP is attached to the first side surface of the reflective polarizer RP. The partial reflection layer BS is attached to the second side surface S8 of the fourth lens E4.

[0095] The spacer element is located between the non-effective diameter regions of the lenses, and the spacer element group 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.

[0096] In this example, the image light from the emitting part F enters the receiving part J after being refracted multiple times 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, and 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 then is reflected for the second time at the partial reflection layer BS. The secondary 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 polarization film LP to the aperture STO, and is finally projected to the receiving part J.

[0097] Table 3 shows the basic parameters of each component of the optical imaging system of Example 1, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm). The image light from the transmitting part F passes through each component in the order of sequence number 24 to sequence number 1 and is finally projected to the receiving part J.

[0098] Table 3

[0099]

[0100]

[0101] In this embodiment, the surfaces of the first lens E1, the second lens E2, the third lens E3 and the fourth lens E4 are all aspherical surfaces. The surface shape of each aspherical lens can be defined by but not limited to the following aspherical surface formula:

[0102]

[0103] Wherein, x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c=1 / R (i.e., the paraxial curvature c is the reciprocal of the curvature radius R in Table 3 above); k is the cone coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. Table 4 shows the high-order coefficients A4, A6, A8, A10, A12, A14, and A16 of the aspheric surface of each lens that can be used in Example 1.

[0104] Table 4

[0105] 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

[0106] Example 2

[0107] Figure 4 FIG. 2 shows a schematic diagram of the structure of an optical imaging system according to Embodiment 2 of the present application. Figure 4As shown, the optical imaging system includes a lens barrel P0, an imaging portion C and a spacing 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.

[0108] The imaging part C includes, from the first side to the second side along the optical axis, a linear polarization 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 partial reflection layer BS. The aperture 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. Exemplarily, the receiving part J may be a human eye, and the transmitting part F may be a display screen.

[0109] 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 1. Its basic parameters are detailed in Tables 3 and 4 and will not be described in detail.

[0110] The difference between this embodiment and the first embodiment is that the lens barrel P0 and at least some elements in the spacer element group have different structural dimensions.

[0111] Example 3

[0112] Figure 5 FIG. 2 shows a schematic diagram of the structure of an optical imaging system according to Embodiment 3 of the present application. Figure 5 As shown, the optical imaging system includes a lens barrel P0, an imaging portion C and a spacing 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.

[0113] The imaging part C includes, from the first side to the second side along the optical axis, a linear polarization 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 partial reflection layer BS. The aperture 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. Exemplarily, the receiving part J may be a human eye, and the transmitting part F may be a display screen.

[0114] 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 1. Its basic parameters are detailed in Tables 3 and 4 and will not be described in detail.

[0115] The difference between this embodiment and the first embodiment is that the lens barrel P0 and at least some elements in the spacer element group have different structural dimensions.

[0116] 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 rays of different wavelengths from the focal point behind the lens. Figure 6 (B1) in FIG. 1 shows the astigmatism curves of the optical imaging lenses of Examples 1 to 3, which represent the meridional image curvature and the sagittal image 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.

[0117] Example 4

[0118] Figure 7 FIG. 1 is a schematic diagram showing the structure of an optical imaging system according to Embodiment 1 of the present application. Figure 7 As shown, the optical imaging system includes a lens barrel P0, an imaging portion C and a spacing 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.

[0119] The imaging part C includes, from the first side to the second side along the optical axis, a linear polarization 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 partial reflection layer BS. The aperture 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. Exemplarily, the receiving part J may be a human eye, and the transmitting part F may be a display screen.

[0120] The first lens E1 has negative optical power, and its first side surface S1 is concave, and its second side surface S2 is convex. The second lens E2 has positive optical power, and its first side surface S3 is concave, and its second side surface S4 is convex. The third lens E3 has negative optical power, and its first side surface S5 is convex, and its second side surface S6 is concave. The fourth lens E4 has positive optical power, and its first side surface S7 is convex, and its second side surface S8 is convex. The second side surface S2 of the first lens E1 is glued to the first side surface S3 of the second lens E2. The second side surface S6 of the third lens E3 is glued 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 polarizer RP is attached to the first side surface of the quarter wave plate QWP, and the linear polarization film LP is attached to the first side surface of the reflective polarizer RP. The partial reflection layer BS is attached to the second side surface S8 of the fourth lens E4.

[0121] The spacer element is located between the non-effective diameter regions of the lenses, and the spacer element group 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.

[0122] In this example, the image light from the emitting part F enters the receiving part J after being refracted multiple times 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, and 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 then is reflected for the second time at the partial reflection layer BS. The secondary 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 polarization film LP to the aperture STO, and is finally projected to the receiving part J.

[0123] Table 5 shows the basic parameters of each component of the optical imaging system of Example 4, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm). The image light from the transmitting part F passes through each component in the order of sequence number 24 to sequence number 1 and is finally projected to the receiving part J.

[0124] Table 5

[0125]

[0126] In this embodiment, 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 lists the high-order coefficients A4, A6, A8, A10, A12, A14 and A16 of the aspherical surfaces of the lenses in Embodiment 4.

[0127] Table 6

[0128]

[0129]

[0130] Example 5

[0131] Figure 8 FIG. 5 shows a schematic diagram of the structure of an optical imaging system according to Embodiment 5 of the present application. Figure 8As shown, the optical imaging system includes a lens barrel P0, an imaging portion C and a spacing 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.

[0132] The imaging part C includes, from the first side to the second side along the optical axis, a linear polarization 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 partial reflection layer BS. The aperture 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. Exemplarily, the receiving part J may be a human eye, and the transmitting part F may be a display screen.

[0133] 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. Its basic parameters are detailed in Tables 5 and 6 and will not be described in detail.

[0134] The difference between this embodiment and Embodiment 4 is that the lens barrel P0 and at least some elements in the spacer element group have different structural dimensions.

[0135] Example 6

[0136] Fig. 9 FIG. 6 is a schematic diagram showing the structure of an optical imaging system according to Embodiment 6 of the present application. Fig. 9 As shown, the optical imaging system includes a lens barrel P0, an imaging portion C and a spacing 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.

[0137] The imaging part C includes, from the first side to the second side along the optical axis, a linear polarization 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 partial reflection layer BS. The aperture 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. Exemplarily, the receiving part J may be a human eye, and the transmitting part F may be a display screen.

[0138] 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. Its basic parameters are detailed in Tables 5 and 6 and will not be described in detail.

[0139] The difference between this embodiment and Embodiment 4 is that the lens barrel P0 and at least some elements in the spacer element group have different structural dimensions.

[0140] Fig.10(A2) in FIG. 1 shows the axial chromatic aberration curves of the optical imaging lenses of Examples 4 to 6, which indicate the deviation of light rays of different wavelengths from the focal point behind the lens. Fig.10 (B2) in FIG. 1 shows the astigmatism curves of the optical imaging lenses of Examples 4 to 6, which represent the meridional image curvature and the sagittal image curvature. Fig.10 (C2) in FIG. 4 shows the distortion curves of the optical imaging lenses of Examples 4 to 6, which represent the distortion values ​​corresponding to different field angles. Fig.10 It can be seen that the optical imaging lenses provided in Examples 4 to 6 can achieve good imaging quality.

[0141] Example 7

[0142] Fig.11 FIG. 2 shows a schematic diagram of the structure of an optical imaging system according to Embodiment 7 of the present application. Fig.11 As shown, the optical imaging system includes a lens barrel P0, an imaging portion C and a spacing 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.

[0143] The imaging part C includes, from the first side to the second side along the optical axis, a linear polarization 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 partial reflection layer BS. The aperture 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. Exemplarily, the receiving part J may be a human eye, and the transmitting part F may be a display screen.

[0144] The first lens E1 has negative optical power, and its first side surface S1 is concave, and its second side surface S2 is convex. The second lens E2 has negative optical power, and its first side surface S3 is concave, and its second side surface S4 is convex. The third lens E3 has negative optical power, and its first side surface S5 is convex, and its second side surface S6 is concave. The fourth lens E4 has positive optical power, and its first side surface S7 is convex, and its second side surface S8 is convex. The second side surface S2 of the first lens E1 is glued to the first side surface S3 of the second lens E2. The second side surface S6 of the third lens E3 is glued 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 polarizer RP is attached to the first side surface of the quarter wave plate QWP, and the linear polarization film LP is attached to the first side surface of the reflective polarizer RP. The partial reflection layer BS is attached to the second side surface S8 of the fourth lens E4.

[0145] The spacer element is located between the non-effective diameter regions of the lenses, and the spacer element group 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.

[0146] In this example, the image light from the emitting part F enters the receiving part J after being refracted multiple times 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, and 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 then is reflected for the second time at the partial reflection layer BS. The secondary 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 polarization film LP to the aperture STO, and is finally projected to the receiving part J.

[0147] Table 7 shows the basic parameters of each component of the optical imaging system of Example 7, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm). The image light from the transmitting part F passes through each component in the order of sequence number 24 to sequence number 1 and is finally projected to the receiving part J.

[0148] Table 7

[0149]

[0150] In this embodiment, 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 8 lists the high-order coefficients A4, A6, A8, A10, A12, A14, A16 of the aspherical surfaces of the lenses in Embodiment 7.

[0151] Table 8

[0152]

[0153]

[0154] Example 8

[0155] Fig.12 FIG. 8 is a schematic diagram showing the structure of an optical imaging system according to Embodiment 8 of the present application. Fig.12As shown, the optical imaging system includes a lens barrel P0, an imaging portion C and a spacing 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.

[0156] The imaging part C includes, from the first side to the second side along the optical axis, a linear polarization 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 partial reflection layer BS. The aperture 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. Exemplarily, the receiving part J may be a human eye, and the transmitting part F may be a display screen.

[0157] 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. Its basic parameters are detailed in Tables 7 to 8 and will not be described in detail.

[0158] The difference between this embodiment and Embodiment 7 is that the lens barrel P0 and at least some elements in the spacer element group have different structural dimensions.

[0159] Example 9

[0160] Fig.13 FIG. 1 is a schematic diagram showing the structure of an optical imaging system according to Embodiment 9 of the present application. Fig.13 As shown, the optical imaging system includes a lens barrel P0, an imaging portion C and a spacing 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.

[0161] The imaging part C includes, from the first side to the second side along the optical axis, a linear polarization 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 partial reflection layer BS. The aperture 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. Exemplarily, the receiving part J may be a human eye, and the transmitting part F may be a display screen.

[0162] 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. Its basic parameters are detailed in Tables 7 to 8 and will not be described in detail.

[0163] The difference between this embodiment and Embodiment 7 is that the lens barrel P0 and at least some elements in the spacer element group have different structural dimensions.

[0164] Fig.14(A3) in FIG. 1 shows the axial chromatic aberration curves of the optical imaging lenses of Examples 7 to 9, which indicate the deviation of light rays of different wavelengths from the focal point behind the lens. Fig.14 (B3) in FIG. 1 shows the astigmatism curves of the optical imaging lenses of Examples 7 to 9, which represent the meridional image curvature and the sagittal image curvature. Fig.14 (C3) in FIG. 1 shows the distortion curves of the optical imaging lenses of Examples 7 to 9, which represent the distortion values ​​corresponding to different field angles. Fig.14 It can be seen that the optical imaging lenses provided in Examples 7 to 9 can achieve good imaging quality.

[0165] Table 9 gives the parameter values ​​of f1, f2, f3, and f4 of each embodiment in Embodiment 1 to Embodiment 9, and the units of the parameters listed in Table 9 are all millimeters (mm).

[0166] Table 9

[0167]

[0168] Table 10 gives the values ​​of parameters of at least some elements in the lens barrel P0 and the spacer element group in each embodiment from Embodiment 1 to Embodiment 9. Among them, some parameters can be calculated according to Figure 1 The parameters listed in Table 10 are measured using the marking method shown in the figure, and the units of the parameters listed in Table 10 are all millimeters (mm).

[0169] Table 10

[0170] Parameters / Examples 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

[0171] In summary, the optical imaging systems in Examples 1 to 9 satisfy the relationship shown in Table 11.

[0172] Table 11

[0173] Conditional / Example 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

[0174] The present application also provides an optical device, which may be an independent projection device such as a projector, or a projection module integrated in a mobile electronic device such as a virtual reality device or an augmented reality device. The optical device is equipped with the optical imaging system described above.

[0175] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other.

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 with 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 with 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 partial 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 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.

2. The optical imaging system according to claim 1, characterized in that: 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: 0.47≤(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 spacing element along the optical axis.

3. The optical imaging system according to claim 1, characterized in that: 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 spacing element.

4. The optical imaging system according to claim 1, characterized in that: 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: 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.

5. The optical imaging system according to claim 1, characterized in that: 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: 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 spacing element.

6. The optical imaging system according to claim 1, characterized in that: 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: -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 spacing element.

7. The optical imaging system according to claim 1, characterized in that: 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: 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 spacing element.

8. The optical imaging system according to claim 1, characterized in that: 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: 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 spacing 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 radius of curvature 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 polarization 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