Optical imaging system

Abstract

The present application relates to a kind of optical imaging systems, including receiving part, imaging part and emitting part, imaging part includes barrel and optical assembly and multiple spacing elements housed in barrel, optical assembly includes first lens, second lens, flat plate and rear group lens by near receiving side to near emitting side are sequentially arranged, and rear group lens includes third lens;Partially reflective layer is equipped on the near emitting side surface of first lens;Linear polarizer, reflective polarizing element, quarter-wave plate are sequentially arranged by near receiving side to near emitting side on the near receiving side surface of first lens;Diffractive element is equipped on the near receiving side of flat plate;Rear group lens includes third lens;First lens and second lens cement;The near receiving side surface of first lens and the near emitting side surface of second lens are both plane.The optical imaging system of the present application can eliminate the chromatic aberration of optical imaging system, thereby reducing the performance loss of virtual display system.

Description

Technical Field

[0001] This invention relates to the field of optical imaging system technology, and more particularly to an optical imaging system. Background Technology

[0002] With the rapid development of virtual reality (VR) technology, developers are constantly pushing the boundaries of system performance, raising the requirements for optical systems to new heights. In VR display solutions that utilize folded optical paths—compact and optically efficient solutions—traditional designs typically employ two sheets of low-refractive-index resin to achieve the folding of the optical path. However, limited by the physical properties of the materials themselves and the design bottlenecks of the optical architecture, such systems often struggle to avoid chromatic aberration. To optimize the user experience and reduce visual blurring and color deviation, developers have had to resort to chromatic aberration compensation at the display screen level, which undoubtedly consumes valuable chip processing resources, leading to a decrease in overall performance. Therefore, providing an optical imaging system that can significantly reduce chromatic aberration to minimize system performance loss and improve image quality is particularly urgent. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention aims to provide an optical imaging system that can reduce chromatic aberration, reduce performance loss in virtual display systems, and improve imaging quality.

[0004] To achieve the above-mentioned objectives, the present invention provides an optical imaging system, including a receiving unit, an imaging unit, and a transmitting unit. The imaging unit includes a lens barrel and optical components and multiple spacer elements housed within the lens barrel. The optical components include a first lens, a second lens, a flat plate, and a rear lens group arranged sequentially from near the receiving side to near the transmitting side. The rear lens group includes a third lens. The first lens has positive optical power; the second lens has negative optical power; the third lens has positive optical power; and the first lens and the second lens are cemented together.

[0005] The first lens has a partial reflective layer on its near-emitting side; the first lens has, from the near-receiving side to the near-emitting side, the following components are arranged in sequence: a linear polarizer, a reflective polarizing element, and a quarter-wave plate.

[0006] The plate is provided with a diffraction element on the receiving side;

[0007] The near-receiving side of the first lens and the near-emitting side of the second lens are both planar.

[0008] According to one technical solution of the present invention, the rear lens group further includes a fourth lens disposed on the near-emission side of the third lens, the fourth lens having positive optical power.

[0009] According to one technical solution of the present invention, the plurality of spacer elements includes: a first spacer element, which is disposed on the near-emission side of the first lens and at least partially contacts the near-emission side of the first lens;

[0010] The optical imaging system satisfies: 1.35≤EP01 / (dlp+drp+dqwp+CT1)≤1.72;

[0011] Wherein, EP01 is the distance along the optical axis from the near-receiving end face of the lens barrel to the near-emitting side face of the first spacer element; dlp is the thickness of the linear polarizer on the optical axis; drp is the thickness of the reflective polarizing element on the optical axis; dqwp is the thickness of the quarter-wave plate on the optical axis; and CT1 is the center thickness of the first lens.

[0012] According to one technical solution of the present invention, the plurality of spacer elements includes: a first spacer element, which is disposed on the near-emission side of the first lens and at least partially contacts the near-emission side of the first lens;

[0013] The optical imaging system satisfies: -12.87≤(Nlp+Nrp+Nqwp+N1)*R2 / d1s≤-12.04;

[0014] Wherein, Nlp is the refractive index of the linear polarizer, Nrp is the refractive index of the reflective polarizing element, Nqwp is the refractive index of the quarter-wave plate, N1 is the refractive index of the first lens, R2 is the radius of curvature of the near-emitting side of the first lens, and D1s is the outer diameter of the near-receiving side of the first spacer element.

[0015] According to one technical solution of the present invention, the plurality of spacer elements includes: a second spacer element, disposed on the near-emission side of the second lens, and at least partially in contact with the near-emission side of the second lens or the near-emission side of the plate;

[0016] The optical imaging system satisfies: 6.43≤D2s / (CT1+CT2)≤8.43;

[0017] Wherein, D2s is the outer diameter of the near-receiving side of the second spacer element, CT1 is the center thickness of the first lens, and CT2 is the center thickness of the second lens.

[0018] According to one technical solution of the present invention, the plurality of spacer elements includes: a second spacer element, disposed on the near-emission side of the second lens, and at least partially in contact with the near-emission side of the second lens or the near-emission side of the plate;

[0019] The optical imaging system satisfies: -3.40≤R3*N2 / d2s≤-2.99;

[0020] Wherein, R3 is the radius of curvature of the near-receiving side of the second lens, N3 is the refractive index of the third lens, and d2s is the inner diameter of the near-receiving side of the second spacer element.

[0021] According to one technical solution of the present invention, the plurality of spacer elements include: a first spacer element disposed on the near-emission side of the first lens and at least partially in contact with the near-emission side of the first lens; and a second spacer element disposed on the near-emission side of the second lens and at least partially in contact with the near-emission side of the second lens or with the near-emission side of the plate.

[0022] The optical imaging system satisfies: 1.69≤EP12 / (CT2+T2t)≤2.29;

[0023] Wherein, EP12 is the distance between the first spacer element and the second spacer element along the optical axis, CT2 is the center thickness of the second lens, and T2t is the air gap between the second lens and the plate along the optical axis.

[0024] According to one technical solution of the present invention, the plurality of spacer elements include: a first spacer element disposed on the near-emission side of the first lens and at least partially in contact with the near-emission side of the first lens; and a second spacer element disposed on the near-emission side of the second lens and at least partially in contact with the near-emission side of the second lens or with the near-emission side of the plate.

[0025] The optical imaging system satisfies: 0.55≤(EP12+CP2) / T23≤1.99;

[0026] Wherein, EP12 is the distance between the first spacer element and the second spacer element along the optical axis, CP2 is the maximum thickness of the second spacer element along the optical axis, and T23 is the air gap between the second lens and the third lens on the optical axis.

[0027] According to one technical solution of the present invention, the plurality of spacer elements includes: a second spacer element, disposed on the near-emission side of the second lens, and at least partially in contact with the near-emission side of the second lens or the near-emission side of the plate;

[0028] The optical imaging system satisfies: 4.61≤D2m / (CT3+CTt)≤8.62;

[0029] Wherein, D2m is the outer diameter of the near-emitting side of the second spacer element, CT3 is the center thickness of the third lens, and CTt is the center thickness of the plate.

[0030] According to one technical solution of the present invention, the plurality of spacer elements includes: a second spacer element, disposed on the near-emission side of the second lens, and at least partially in contact with the near-emission side of the second lens or the near-emission side of the plate;

[0031] The optical imaging system satisfies: 0.74≤R5 / d2m≤1.46;

[0032] Wherein, R5 is the radius of curvature of the near-receiving side of the third lens, and d2m is the inner diameter of the near-emitting side of the second spacer element.

[0033] According to one technical solution of the present invention, the optical imaging system satisfies: 1.81≤D0m / (TAN(Semi-FOV)*L)≤2.10;

[0034] Wherein, D0m is the outer diameter of the side closest to the emitter on the rear end face of the lens barrel, Semi-FOV is half of the maximum field of view of the optical imaging system, and L is the maximum height of the lens barrel.

[0035] According to one technical solution of the present invention, the plurality of spacer elements includes: a third spacer element, which is disposed on the near-emission side of the third lens and at least partially contacts the near-emission side of the third lens;

[0036] The optical imaging system satisfies: 12.08 ≤ D3m / CT4 ≤ 22.20;

[0037] Wherein, D3m is the outer diameter of the near-emitting side of the third spacer element, and CT4 is the center thickness of the fourth lens.

[0038] According to one technical solution of the present invention, the plurality of spacer elements includes: a third spacer element, which is disposed on the near-emission side of the third lens and at least partially contacts the near-emission side of the third lens;

[0039] The optical imaging system satisfies: 1.23≤R7 / (D3m-d3m)≤3.30;

[0040] Wherein, R7 is the radius of curvature of the near-receiving side of the fourth lens, D3m is the outer diameter of the near-emitting side of the third spacer element, and d3m is the inner diameter of the near-emitting side of the third spacer element.

[0041] The beneficial effects of this invention are:

[0042] The optical imaging system of this invention features miniaturization, low chromatic aberration, and high imaging quality. The aforementioned polarization element and partial reflective layer form a catadioptric system, shortening the overall system length and reducing the overall height, thus facilitating miniaturization. The diffraction element is located on a flat plate, which is easy to manufacture and can be equivalent to a negative Abbe number lens, beneficial for chromatic aberration correction. The rear lens group, combined with the diffraction element, effectively reduces chromatic aberration. Cementing the first and second lenses reduces reflection in the visible light band, improving the contrast of the optical imaging system. By setting the near-receiving side of the first lens and the near-emitting side of the second lens as a plane, the two lenses form a parallel plate, effectively reducing surface reflection, increasing transmittance, suppressing stray light, and improving imaging contrast. Therefore, the optical imaging system design of this invention effectively reduces chromatic aberration, minimizes performance loss in virtual display systems, and improves imaging quality. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0044] Figure 1A , Figure 1B and Figure 1C A schematic diagram of the structure and schematic diagrams of some parameters of an optical imaging system according to the present invention are shown respectively;

[0045] Figure 2A , Figure 2B and Figure 2C Schematic diagrams of optical imaging systems 1001, 1002, and 1003 according to Embodiment 1 of the present invention are shown respectively.

[0046] Figure 2D , Figure 2E , Figure 2F and Figure 2G The on-axis chromatic aberration curve, astigmatism curve, distortion curve, and magnification chromatic aberration curve of the optical imaging system according to Embodiment 1 of the present invention are shown respectively.

[0047] Figure 3A , Figure 3B and Figure 3C Schematic diagrams of optical imaging systems 2001, 2002, and 2003 according to Embodiment 2 of the present invention are shown respectively.

[0048] Figure 3D , Figure 3E , Figure 3F and Figure 3GThe on-axis chromatic aberration curve, astigmatism curve, distortion curve, and magnification chromatic aberration curve of the optical imaging system according to Embodiment 2 of the present invention are shown respectively.

[0049] Figure 4A , Figure 4B and Figure 4C Schematic diagrams of optical imaging systems 3001, 3002 and 3003 according to Embodiment 3 of the present invention are shown respectively.

[0050] Figure 4D , Figure 4E , Figure 4F and Figure 4G The on-axis chromatic aberration curve, astigmatism curve, distortion curve, and magnification chromatic aberration curve of the optical imaging system according to Embodiment 3 of the present invention are shown respectively. Detailed Implementation

[0051] To better understand the invention, various aspects of the invention will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of the invention and are not intended to limit the scope of the invention in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0052] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of the invention, the first lens discussed below may also be referred to as the second lens or the third lens, or the first lens may also be referred to as the first lens element.

[0053] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0054] In this paper, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface shape in the paraxial region can be determined by the sign of the R value (R refers to the radius of curvature of the paraxial region). In this paper, the receiving part is the human eye, and the emitting part is the display screen. The surface of each lens closest to the receiving part is called the near-receiving side of the lens, and the surface of each lens closest to the emitting part is called the near-emitting side of the lens. For the near-receiving side, when the R value is positive, it is determined to be convex, and when the R value is negative, it is determined to be concave; for the near-emitting side, when the R value is positive, it is determined to be concave, and when the R value is negative, it is determined to be convex.

[0055] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of the invention, the word "may" is used to mean "one or more embodiments of the invention." And the term "exemplary" is intended to refer to an example or illustration.

[0056] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense, unless expressly so defined herein.

[0057] It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this invention can be combined with each other. The following embodiments only illustrate several implementation methods of this invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this invention. 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 this invention, and these all fall within the protection scope of this invention.

[0058] like Figure 1A , 1BAs shown in Figure 1C, the optical imaging system of an exemplary embodiment of the present invention includes a lens barrel, an imaging unit, and multiple spacer elements. The imaging unit includes a first lens, a second lens, a plate, and a rear lens group arranged sequentially from the near-receiving side to the near-emitting side; a partial reflective layer is provided on the near-emitting side of the first lens; a linear polarizer, a reflective polarizing element, and a quarter-wave plate are sequentially provided on the near-receiving side of the first lens from the near-receiving side to the near-emitting side; a diffraction element is provided on the near-receiving side of the plate; the rear lens group includes a third lens, or the rear lens group includes a third lens and a fourth lens.

[0059] Optical imaging systems are characterized by miniaturized equipment, low chromatic aberration, and high imaging quality. In an optical imaging system, a linear polarizer absorbs linearly polarized light in a specific direction and transmits linearly polarized light perpendicular to that direction. Since reflective polarizers and quarter-wave plates can cause some light leakage, adding a linear polarizer absorbs this leakage, reducing ghosting and improving contrast. The reflective polarizer reflects S-polarized light and transmits P-polarized light. The quarter-wave plate converts linearly polarized light into circularly polarized light and vice versa. A partially reflective layer allows light to pass through and also reflects light. A beam of circularly polarized light is transmitted through the partially reflective layer, becomes S-polarized light after passing through the quarter-wave plate, is reflected by the reflective polarizer, becomes circularly polarized light after passing through the quarter-wave plate, is reflected again by the partially reflective layer, changes its rotation direction, becomes P-polarized light after passing through the quarter-wave plate again, is transmitted through the reflective polarizer, and then reaches the human eye via the linear polarizer. The aforementioned polarizing elements and partially reflective layers constitute a catadioptric system, shortening the overall system length and reducing the overall height, thus facilitating equipment miniaturization. The diffraction element is located on a flat plate, which is easy to manufacture and can be equivalent to a negative Abbe number lens, which is beneficial for chromatic aberration correction. The rear lens group, in combination with the diffraction element, can effectively reduce the chromatic aberration of the system.

[0060] In some embodiments of the present invention, the first lens and the second lens are cemented together, which can reduce the reflection of the first lens and the second lens in the visible light band, improve the transmittance of the optical imaging system, and improve the contrast and imaging quality of the optical imaging system.

[0061] In some embodiments of the present invention, the near-receiving side of the first lens and the near-emitting side of the second lens are planar. By setting the near-receiving side of the first lens and the near-emitting side of the second lens to be planar, the two lenses form a parallel plate, which is subjected to uniform force when in contact with other structural components, and is less prone to lens deformation or surface distortion due to assembly stress, thereby improving imaging stability. At the same time, it can also effectively improve the transmittance of the optical imaging system, suppress stray light, and improve system contrast. In addition, the planar surface is easy to coat with film, and the film layer has good uniformity.

[0062] Therefore, the optical imaging system of the present invention not only significantly reduces chromatic aberration, but also improves the contrast of the optical imaging system, effectively reducing the performance loss of the virtual display system and improving the imaging quality of the system.

[0063] In some embodiments of the present invention, the first lens has positive optical power, with its near-receiving side being a plane and its near-emitting side being a convex surface; the second lens has negative optical power, with its near-receiving side being a concave surface and its near-emitting side being a plane; the third lens has positive optical power, with its near-receiving side being a convex surface and its near-emitting side being a concave surface; and the fourth lens has positive optical power, with its near-receiving side being a convex surface and its near-emitting side being a plane.

[0064] The plurality of spacers include: a first spacer element disposed on the near-emission side of the first lens and in at least partial contact with the near-emission side of the first lens; a second spacer element disposed on the near-emission side of the second lens and in at least partial contact with the near-emission side of the second lens or with the near-emission side of the plate; and a third spacer element disposed on the near-emission side of the third lens and in at least partial contact with the near-emission side of the third lens.

[0065] In some embodiments of the present invention, the optical imaging system satisfies: 1.35≤EP01 / (dlp+drp+dqwp+CT1)≤1.72;

[0066] Wherein, EP01 is the distance along the optical axis from the near-receiving end face of the lens barrel to the near-emitting side face of the first spacer element; dlp is the thickness of the linear polarizer on the optical axis; drp is the thickness of the reflective polarizing element on the optical axis; dqwp is the thickness of the quarter-wave plate on the optical axis; and CT1 is the center thickness of the first lens.

[0067] By properly controlling this conditional range, a compact design of the optical imaging system can be achieved, reducing the size and weight of the device and improving its ease of use and comfort. It also helps control the edge thickness of the first lens, thereby ensuring its manufacturability.

[0068] In some embodiments of the present invention, the optical imaging system satisfies: -12.87≤(Nlp+Nrp+Nqwp+N1)*R2 / d1s≤-12.04; where Nlp is the refractive index of the linear polarizer, Nrp is the refractive index of the reflective polarizing element, Nqwp is the refractive index of the quarter-wave plate, N1 is the refractive index of the first lens, R2 is the radius of curvature of the near-emitting side of the first lens, and D1s is the outer diameter of the near-receiving side of the first spacer element.

[0069] By reasonably controlling the range of this conditional expression, precise control of the polarization state can be achieved, which is beneficial to improving the imaging stability of the system. Since the linear polarization element, the reflective polarizing element, and the quarter-wave plate are all located on the near-receiving side of the first lens, the first lens plays a crucial role in polarization state control. However, this also makes the first lens relatively sensitive and prone to generating internal stray light. Therefore, by simultaneously constraining the inner diameter of the near-receiving side of the first spacer element, stray light can be effectively blocked, reducing the risk of internal stray light and improving the imaging quality of the system.

[0070] In some embodiments of the present invention, the optical imaging system satisfies: 6.43≤D2s / (CT1+CT2)≤8.43; where D2s is the outer diameter of the near-receiving side of the second spacer element, CT1 is the center thickness of the first lens, and CT2 is the center thickness of the second lens.

[0071] By controlling the ratio of the outer diameter of the near-receiving side of the second spacer element to the sum of the center thicknesses of the first and second lenses within a reasonable range, it is possible to help control and optimize the lens spacing and aberration compensation, thereby improving the full field-of-view imaging sharpness. Simultaneously, when the first and second lenses are cemented together, their diameter-to-thickness ratio is particularly important during assembly. By constraining the aforementioned conditional range, assembly tolerances can be reduced, which is beneficial for assembly stability.

[0072] In some embodiments of the present invention, the optical imaging system satisfies: -3.40≤R3*N2 / d2s≤-2.99; where R3 is the radius of curvature of the near-receiving side of the second lens, N3 is the refractive index of the third lens, and d2s is the inner diameter of the near-receiving side of the second spacer element.

[0073] By properly controlling this conditional range, large field-of-view aberrations can be corrected, improving the sharpness of the entire field of view imaging, helping to control the angle and position of incident light rays, and optimizing lens performance. Simultaneously, controlling the inner diameter of the near-receiving side of the second spacer element helps to block stray light and improve the imaging quality of the optical imaging system.

[0074] In some embodiments of the present invention, the optical imaging system satisfies: 1.69≤EP12 / (CT2+T2t)≤2.29; where EP12 is the distance between the first spacer element and the second spacer element along the optical axis, CT2 is the center thickness of the second lens, and T2t is the air gap between the second lens and the plate along the optical axis.

[0075] By properly controlling this conditional range, the strength of optical components can be guaranteed, the axial dimensions of the optical system can be balanced, the requirements for the lens barrel shape can be met, and the convenience and comfort of wearing can be improved. At the same time, it helps to control the edge thickness of the second lens, ensuring that the second lens has good manufacturability.

[0076] In some embodiments of the present invention, the optical imaging system satisfies: 0.55≤(EP12+CP2) / T23≤1.99; where EP12 is the distance between the first spacer element and the second spacer element along the optical axis, CP2 is the maximum thickness of the second spacer element along the optical axis, and T23 is the air gap between the second lens and the third lens on the optical axis.

[0077] By properly controlling this conditional range, assembly and long-term reliability can be improved, failure risks reduced, imaging accuracy of the optical imaging system ensured, and field-of-view quality stabilized. Simultaneously, a balance is struck between structural reliability and lightweight design to meet the needs of head-mounted displays.

[0078] In some embodiments of the present invention, the optical imaging system satisfies: 4.61≤D2m / (CT3+CTt)≤8.62; where D2m is the outer diameter of the near-emitting side of the second spacer element, CT3 is the center thickness of the third lens, and CTt is the center thickness of the plate.

[0079] By properly controlling the range of this condition, the reliability of the support between the third lens and the plate can be ensured, optical path deviation can be avoided, stray light suppression can be optimized, and the imaging quality of the optical imaging system can be improved.

[0080] In some embodiments of the present invention, the optical imaging system satisfies: 0.74≤R5 / d2m≤1.46; where R5 is the radius of curvature of the near-receiving side of the third lens, and d2m is the inner diameter of the near-emitting side of the second spacer element.

[0081] By controlling the ratio between the radius of curvature of the near-receiving side of the third lens and the inner diameter of the near-emitting side of the second spacer element within a reasonable range, it is helpful to control the shape of the third lens and improve its manufacturability.

[0082] In some embodiments of the present invention, the optical imaging system satisfies: 1.81≤D0m / (TAN(Semi-FOV)*L)≤2.10; where D0m is the outer diameter of the near-emission end face of the lens barrel, Semi-FOV is half of the maximum field of view of the optical imaging system, and L is the maximum height of the lens barrel.

[0083] By properly controlling this conditional range, a wider field of view can be provided, allowing users to see more virtual or augmented reality content. Simultaneously, the large field of view coverage remains uncropped, avoiding black borders at the edges of the image. Furthermore, by controlling the outer diameter and maximum height of the lens barrel, miniaturization and weight reduction are achieved.

[0084] In some embodiments of the present invention, the optical imaging system satisfies: 12.08≤D3m / CT4≤22.20; where D3m is the outer diameter of the near-emitting side of the third spacer element, and CT4 is the center thickness of the fourth lens.

[0085] By reasonably controlling the range of this condition, structural support can be guaranteed, the structural failure of the third spacer element can be avoided from affecting the stable lens spacing, and the system volume and weight can be controlled to avoid structural interference and stray light.

[0086] In some embodiments of the present invention, the optical imaging system satisfies: 1.23≤R7 / (D3m-d3m)≤3.30; where R7 is the radius of curvature of the near-receiving side of the fourth lens, D3m is the outer diameter of the near-emitting side of the third spacer element, and d3m is the inner diameter of the near-emitting side of the third spacer element.

[0087] By properly controlling the range of this conditional formula, on the one hand, the optical correction capability of the fourth lens can be guaranteed, avoiding aberration deterioration and wasted space; on the other hand, the structural strength of the spacer can be guaranteed, preventing lens support failure and insufficient refractive power. Simultaneously, it helps control the shape of the fourth lens and improves its manufacturability.

[0088] The optical imaging system according to the above embodiments of the present invention can employ multiple lenses, such as the three or four lenses mentioned above. By rationally allocating the optical power, surface shape, and arrangement of the spacers of each lens, the range of each lens-tube engagement is made more uniform, enhancing the light-gathering ability and improving the imaging quality of the optical imaging system.

[0089] In some embodiments of the present invention, the lens material in the optical imaging system provided by the present invention can be glass or plastic. When the lens material is plastic, production costs can be effectively reduced. Conversely, when the lens material is glass, the low dispersion characteristic of glass itself can effectively correct the geometric chromatic aberration of the optical system. The optical lens provided by the present invention can adopt an all-plastic lens structure, which not only gives the lens excellent imaging performance but also allows for a more compact lens structure, achieving a good balance between lens miniaturization and high image quality.

[0090] In some embodiments of the present invention, the first lens, second lens, third lens, and fourth lens can be spherical lenses or aspherical lenses. Compared with spherical structures, aspherical structures can effectively reduce the aberrations of the optical system, thereby reducing the number of lenses and the size of the lenses, and better achieving lens miniaturization. More specifically, the first lens, second lens, third lens, and fourth lens of the present invention can all be aspherical lenses, which can effectively reduce the aberrations of the optical lens, thereby reducing the number of lenses and the size of the lenses, and achieving lens miniaturization.

[0091] When an aspherical lens is used, the shapes of each aspherical surface of the optical lens satisfy the following equation:

[0092]

[0093] In the above formula, The height perpendicular to the optical axis is along the optical axis. The axial distance from the vertex to the surface at the location; This represents the curvature at the vertex of the aspherical surface. The conic coefficient; , , , , , , ...represent aspheric coefficients of the fourth, sixth, eighth, tenth, twelfth, fourteenth, and sixteenth orders, respectively.

[0094] The present invention will be further described below with reference to several embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens are different; for specific differences, please refer to the parameter tables of each embodiment. The following embodiments are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention.

[0095] Example 1

[0096] The following is for reference Figures 2A to 2G The optical imaging system 1001, optical imaging system 1002 and optical imaging system 1003 according to Embodiment 1 of the present invention are described. Figure 2A , Figure 2B , Figure 2C Schematic diagrams of optical imaging systems 1001, 1002, and 1003 according to Embodiment 1 of the present invention are shown respectively.

[0097] Among them, optical imaging systems 1001, 1002 and 1003 all include a receiving unit, an imaging unit and a transmitting unit. The imaging unit includes a lens barrel P0, an optical assembly and multiple spacer elements. Optical imaging systems 1001, 1002 and 1003 have the same optical parameters (as shown in Table 1 and Table 2) and different structural parameters (as shown in Table 8).

[0098] The optical components, from near the receiver to near the transmitter, include, in sequence: a linear polarizer LP, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a partial reflective layer BS, a second lens E2, a diffraction element DOE, a flat plate T, a third lens E3, and a fourth lens E4.

[0099] The plurality of spacer elements include a first spacer element P1, a second spacer element P2 and a third spacer element P3, wherein the second spacer element P2 is disposed on the near-emission side of the plate T and is at least partially in contact with the near-emission side of the plate T.

[0100] Furthermore, STO represents the aperture stop, S1 represents the near-receiving side of the first lens L1, S2 represents the near-emitting side of the first lens L1; S3 is the near-receiving side of the second lens E2, S4 is the near-emitting side of the second lens E2; S5 is the near-receiving side of the plate T, S6 is the near-emitting side of the plate T; S7 is the near-receiving side of the third lens E3, S8 is the near-emitting side of the third lens E3; S9 ​​is the near-receiving side of the fourth lens E4; S10 is the near-emitting side of the fourth lens E4; S11 is the first side of the display screen, S12 is the second side of the display screen, and S13 is the image surface of the display screen, wherein, as... Figures 2A to 2C As shown, the first side is the side closest to the optical component, and the second side is the side closest to the image surface.

[0101] Light emitted from the image surface S13 of the display screen passes sequentially through surface S12, surface S11, fourth lens E4, third lens E3, plate T, diffraction element DOE, second lens E2, partial reflective layer BS, first lens E1, and quarter-wave plate QWP to reach reflective polarizing element RP. It is reflected at reflective polarizing element RP and passes through quarter-wave plate QWP and first lens E1 again to reach partial reflective layer BS. After that, the light beam is reflected again at partial reflective layer BS and passes sequentially through first lens E1, quarter-wave plate QWP, reflective polarizing element RP and linear polarizer LP to exit towards aperture STO on the receiving side.

[0102] In this embodiment, the first lens E1 and the second lens E2 are bonded together. A quarter-wave plate QWP can be attached to the near-receiving side of the first lens E1, a reflective polarizing element RP can be attached to the near-receiving side of the quarter-wave plate QWP, and a linear polarizer LP can be attached to the near-receiving side of the reflective polarizing element RP. A diffraction element DOE is disposed on the near-receiving side of the plate T. The partial reflective layer BS can be a semi-transparent, semi-reflective film layer deposited on the near-emitting side of the first lens E1. The diffraction element DOE can be a grating structure etched on the near-emitting side of the plate T.

[0103] Table 1 lists the relevant parameters of each lens in the optical imaging system of this embodiment, including: surface type, radius of curvature, thickness, refractive index of the material, Abbe number and conic coefficient, wherein the units of radius of curvature and thickness are millimeters (mm).

[0104]

[0105] Table 1

[0106] Table 2 lists the conic and aspherical coefficients of each aspherical lens in the optical imaging system of this embodiment, including: A4, A6, A8, A... 10 A 12 A 14 A 16 A 18 A 20 .

[0107]

[0108] Table 2

[0109] Figure 2D The on-axis chromatic aberration curve of the optical imaging system of Embodiment 1 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 2E The astigmatism curves of the optical imaging system of Embodiment 1 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 2F The distortion curves of the optical imaging system of Embodiment 1 are shown, which represent the distortion magnitude values ​​corresponding to different image heights. Figure 2G The magnification chromatic aberration curve of the optical system of Embodiment 1 is shown, which represents the deviation of different image heights on the imaging plane after light passes through the lens. According to Figures 2D to 2G As can be seen, the optical imaging system given in Example 1 can achieve good imaging quality.

[0110] Example 2

[0111] The following is for reference Figures 3A to 3F Optical imaging systems 2001, 2002, and 2003 according to Embodiment 2 of the present invention are described. Figure 3A , Figure 3B , Figure 3C Schematic diagrams of optical imaging systems 2001, 2002, and 2003 according to Embodiment 2 of the present invention are shown respectively.

[0112] Among them, optical imaging systems 2001, 2002 and 2003 all include a receiving unit, an imaging unit and a transmitting unit. The imaging unit includes a lens barrel P0, an optical assembly and multiple spacer elements. Optical imaging systems 2001, 2002 and 2003 have different lens structures, with the same optical parameters (as shown in Tables 3 and 4) and different structural parameters (as shown in Table 8).

[0113] The optical components, from near the receiver to near the transmitter, include, in sequence: a linear polarizer LP, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a partial reflective layer BS, a second lens E2, a diffraction element DOE, a flat plate T, a third lens E3, and a fourth lens E4.

[0114] The plurality of spacer elements include a first spacer element P1, a second spacer element P2 and a third spacer element P3, wherein the second spacer element P2 is disposed on the near-emission side of the plate T and is at least partially in contact with the near-emission side of the plate T.

[0115] Furthermore, STO represents the aperture stop, S1 represents the near-receiving side of the first lens L1, S2 represents the near-emitting side of the first lens L1; S3 is the near-receiving side of the second lens E2, S4 is the near-emitting side of the second lens E2; S5 is the near-receiving side of the plate T, S6 is the near-emitting side of the plate T; S7 is the near-receiving side of the third lens E3, S8 is the near-emitting side of the third lens E3; S9 ​​is the near-receiving side of the fourth lens E4; S10 is the near-emitting side of the fourth lens E4; S11 is the first side of the display screen, S12 is the second side of the display screen, and S13 is the image surface of the display screen, wherein, as... Figures 3A to 3C As shown, the first side is the side closest to the optical component, and the second side is the side closest to the image surface.

[0116] Light emitted from the image surface S13 of the display screen passes sequentially through surface S12, surface S11, fourth lens E4, third lens E3, plate T, diffraction element DOE, second lens E2, partial reflective layer BS, first lens E1, and quarter-wave plate QWP to reach reflective polarizing element RP. It is reflected at reflective polarizing element RP and passes through quarter-wave plate QWP and first lens E1 again to reach partial reflective layer BS. After that, the light beam is reflected again at partial reflective layer BS and passes sequentially through first lens E1, quarter-wave plate QWP, reflective polarizing element RP and linear polarizer LP to exit towards aperture STO on the receiving side.

[0117] In this embodiment, the first lens E1 and the second lens E2 are bonded together. A quarter-wave plate QWP can be attached to the near-receiving side of the first lens E1, a reflective polarizing element RP can be attached to the near-receiving side of the quarter-wave plate QWP, and a linear polarizer LP can be attached to the near-receiving side of the reflective polarizing element RP. A diffraction element DOE is disposed on the near-receiving side of the plate T. The partial reflective layer BS can be a semi-transparent, semi-reflective film layer deposited on the near-emitting side of the first lens E1. The diffraction element DOE can be a grating structure etched on the near-emitting side of the plate T.

[0118] Table 3 lists the relevant parameters of each lens in the optical imaging system of this embodiment, including: surface type, radius of curvature, thickness, refractive index of the material, Abbe number and conic coefficient, wherein the units of radius of curvature and thickness are millimeters (mm).

[0119]

[0120] Table 3

[0121] Table 4 lists the conic and aspherical coefficients of each aspherical lens in the optical imaging system of this embodiment, including: A4, A6, A8, A... 10 A 12 A 14 .

[0122]

[0123] Table 4

[0124] Figure 3D The on-axis chromatic aberration curve of the optical imaging system of Embodiment 2 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 3E The astigmatism curves of the optical imaging system of Embodiment 2 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 3F The distortion curves of the optical imaging system of Embodiment 2 are shown, which represent the distortion magnitude values ​​corresponding to different image heights. Figure 3G The magnification chromatic aberration curve of the optical system in Embodiment 2 is shown, representing the deviation of different image heights on the imaging plane after light passes through the lens. According to... Figures 3D to 3G It can be seen that the optical imaging system given in Example 2 can achieve good imaging quality.

[0125] Example 3

[0126] The following is for reference Figures 4A to 4F The optical imaging systems 3001, 3002 and 3003 according to Embodiment 3 of the present invention are described. Figure 4A , Figure 4B , Figure 4CSchematic diagrams of optical imaging systems 3001, 3002 and 3003 according to Embodiment 3 of the present invention are shown respectively.

[0127] Among them, optical imaging systems 3001, 3002 and 3003 all include a receiving part, an imaging part and a transmitting part. The imaging part includes a lens barrel P0, an optical component and multiple spacer elements. Optical imaging systems 3001, 3002 and 3003 have different lens structures, with the same optical parameters (as shown in Tables 5 and 6) and different structural parameters (as shown in Table 8).

[0128] The optical components, from near the receiver to near the transmitter, include, in sequence: a linear polarizer LP, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a partial reflective layer BS, a second lens E2, a diffraction element DOE, a flat plate T, and a third lens E3.

[0129] The plurality of spacers include a first spacer P1, a second spacer P2, and a second auxiliary spacer P2b. The second spacer P2 is disposed on the near-emitting side of the second lens E2 and is at least partially in contact with the near-emitting side of the second lens E2. The second auxiliary spacer P2b is disposed on the near-emitting side of the plate T and is at least partially in contact with the near-receiving side of the plate T. That is, the second spacer P2 and the second auxiliary spacer P2b are respectively disposed on both sides of the plate T.

[0130] Furthermore, STO represents the aperture stop, S1 represents the near-receiving side of the first lens L1, S2 represents the near-emitting side of the first lens L1; S3 is the near-receiving side of the second lens E2, S4 is the near-emitting side of the second lens E2; S5 is the near-receiving side of the plate T, S6 is the near-emitting side of the plate T; S7 is the near-receiving side of the third lens E3, S8 is the near-emitting side of the third lens E3; S9 ​​is the first side of the display screen, S10 is the second side of the display screen, and S11 is the image side of the display screen, as shown below. Figures 4A to 4C As shown, the first side is the side closest to the optical component, and the second side is the side closest to the image surface.

[0131] Light emitted from the image surface S11 of the display screen passes sequentially through surface S10, surface S9, third lens E3, plate T, diffraction element DOE, second lens E2, partial reflective layer BS, first lens E1, and quarter-wave plate QWP to reach reflective polarizing element RP. It is reflected at reflective polarizing element RP and passes through quarter-wave plate QWP and first lens E1 again to reach partial reflective layer BS. After that, the light beam is reflected again at partial reflective layer BS and passes sequentially through first lens E1, quarter-wave plate QWP, reflective polarizing element RP and linear polarizer LP to exit towards aperture STO on the receiving side.

[0132] In this embodiment, the first lens E1 and the second lens E2 are bonded together. A quarter-wave plate QWP can be attached to the near-receiving side of the first lens E1, a reflective polarizing element RP can be attached to the near-receiving side of the quarter-wave plate QWP, and a linear polarizer LP can be attached to the near-receiving side of the reflective polarizing element RP. A diffraction element DOE is disposed on the near-receiving side of the plate T. The partial reflective layer BS can be a semi-transparent, semi-reflective film layer deposited on the near-emitting side of the first lens E1. The diffraction element DOE can be a grating structure etched on the near-emitting side of the plate T.

[0133] Table 5 lists the relevant parameters of each lens in the optical imaging system of this embodiment, including: surface type, radius of curvature, thickness, refractive index of the material, Abbe number and conic coefficient, wherein the units of radius of curvature and thickness are millimeters (mm).

[0134]

[0135] Table 5

[0136] Table 6 lists the conic and aspherical coefficients of each aspherical lens in the optical imaging system of this embodiment, including: A4, A6, A8, A... 10 A 12 A 14 .

[0137]

[0138] Table 6

[0139] Figure 4D The on-axis chromatic aberration curve of the optical imaging system of Embodiment 3 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 4E The astigmatism curves of the optical imaging system of Embodiment 3 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 4F The distortion curves of the optical imaging system of Embodiment 3 are shown, which represent the distortion magnitude values ​​corresponding to different image heights. Figure 4GThe magnification chromatic aberration curve of the optical system in Embodiment 3 is shown, representing the deviation of different image heights on the imaging plane after light passes through the lens. According to... Figures 4D to 4G As can be seen, the optical imaging system given in Example 3 can achieve good imaging quality.

[0140] In summary, the optical parameters of the optical imaging systems 1001, 1002, 1003, 2001, 2002, 2003, 3001, 3002 and 3003 in Examples 1 to 3 are shown in Table 7 below.

[0141]

[0142] Table 7

[0143] The structural parameters of the optical imaging systems 1001, 1002, 1003, 2001, 2002, 2003, 3001, 3002 and 3003 in Examples 1 to 3 are shown in Table 8 below, in millimeters (mm).

[0144]

[0145] Table 8

[0146] The optical imaging systems 1001, 1002, 1003, 2001, 2002, 2003, 3001, 3002, and 3003 in Examples 1 to 3 satisfy the relationships shown in Table 9.

[0147]

[0148] Table 9

[0149] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention is not limited to the specific combination of the above-described technical features, but also includes other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this invention.

Claims

1. An optical imaging system, comprising a receiving unit, an imaging unit, and a transmitting unit, wherein the imaging unit includes a lens barrel and optical components and a plurality of spacer elements housed within the lens barrel, characterized in that, The optical assembly includes a first lens, a second lens, a flat plate, and a rear lens group arranged sequentially from the near-receiving side to the near-emitting side, wherein the rear lens group includes a third lens; the first lens has positive optical power; the second lens has negative optical power; the third lens has positive optical power; and the first lens and the second lens are cemented together. The first lens has a partial reflective layer on its near-emitting side; the first lens has, from the near-receiving side to the near-emitting side, the following components are arranged in sequence: a linear polarizer, a reflective polarizing element, and a quarter-wave plate. The plate is provided with a diffraction element on the receiving side; The near-receiving side of the first lens and the near-emitting side of the second lens are both planar.

2. The optical imaging system according to claim 1, characterized in that, The rear lens group also includes a fourth lens disposed on the near-emission side of the third lens, the fourth lens having positive optical power.

3. The optical imaging system according to claim 1 or 2, characterized in that, The plurality of spacer elements includes: a first spacer element disposed on the near-emission side of the first lens and in at least partial contact with the near-emission side of the first lens; The optical imaging system satisfies: 1.35≤EP01 / (dlp+drp+dqwp+CT1)≤1.72; Wherein, EP01 is the distance along the optical axis from the near-receiving end face of the lens barrel to the near-emitting side face of the first spacer element; dlp is the thickness of the linear polarizer on the optical axis; drp is the thickness of the reflective polarizing element on the optical axis; dqwp is the thickness of the quarter-wave plate on the optical axis; and CT1 is the center thickness of the first lens.

4. The optical imaging system according to claim 1 or 2, characterized in that, The plurality of spacer elements includes: a first spacer element disposed on the near-emission side of the first lens and in at least partial contact with the near-emission side of the first lens; The optical imaging system satisfies: -12.87≤(Nlp+Nrp+Nqwp+N1)*R2 / d1s≤-12.04; Wherein, Nlp is the refractive index of the linear polarizer, Nrp is the refractive index of the reflective polarizing element, Nqwp is the refractive index of the quarter-wave plate, N1 is the refractive index of the first lens, R2 is the radius of curvature of the near-emitting side of the first lens, and D1s is the outer diameter of the near-receiving side of the first spacer element.

5. The optical imaging system according to claim 1 or 2, characterized in that, The plurality of spacer elements includes: a second spacer element disposed on the near-emission side of the second lens and in at least partial contact with the near-emission side of the second lens or with the near-emission side of the plate; The optical imaging system satisfies: 6.43≤D2s / (CT1+CT2)≤8.43; Wherein, D2s is the outer diameter of the near-receiving side of the second spacer element, CT1 is the center thickness of the first lens, and CT2 is the center thickness of the second lens.

6. The optical imaging system according to claim 1 or 2, characterized in that, The plurality of spacer elements includes: a second spacer element disposed on the near-emission side of the second lens and in at least partial contact with the near-emission side of the second lens or with the near-emission side of the plate; The optical imaging system satisfies: -3.40≤R3*N2 / d2s≤-2.99; Wherein, R3 is the radius of curvature of the near-receiving side of the second lens, N3 is the refractive index of the third lens, and d2s is the inner diameter of the near-receiving side of the second spacer element.

7. The optical imaging system according to claim 1 or 2, characterized in that, The plurality of spacer elements include: a first spacer element disposed on the near-emission side of the first lens and in at least partial contact with the near-emission side of the first lens; and a second spacer element disposed on the near-emission side of the second lens and in at least partial contact with the near-emission side of the second lens or with the near-emission side of the plate. The optical imaging system satisfies: 1.69≤EP12 / (CT2+T2t)≤2.29; Wherein, EP12 is the distance between the first spacer element and the second spacer element along the optical axis, CT2 is the center thickness of the second lens, and T2t is the air gap between the second lens and the plate along the optical axis.

8. The optical imaging system according to claim 1 or 2, characterized in that, The plurality of spacer elements include: a first spacer element disposed on the near-emission side of the first lens and in at least partial contact with the near-emission side of the first lens; and a second spacer element disposed on the near-emission side of the second lens and in at least partial contact with the near-emission side of the second lens or with the near-emission side of the plate. The optical imaging system satisfies: 0.55≤(EP12+CP2) / T23≤1.99; Wherein, EP12 is the distance between the first spacer element and the second spacer element along the optical axis, CP2 is the maximum thickness of the second spacer element along the optical axis, and T23 is the air gap between the second lens and the third lens on the optical axis.

9. The optical imaging system according to claim 1 or 2, characterized in that, The plurality of spacer elements includes: a second spacer element disposed on the near-emission side of the second lens and in at least partial contact with the near-emission side of the second lens or with the near-emission side of the plate; The optical imaging system satisfies: 4.61≤D2m / (CT3+CTt)≤8.62; Wherein, D2m is the outer diameter of the near-emitting side of the second spacer element, CT3 is the center thickness of the third lens, and CTt is the center thickness of the plate.

10. The optical imaging system according to claim 1 or 2, characterized in that, The plurality of spacer elements includes: a second spacer element disposed on the near-emission side of the second lens and in at least partial contact with the near-emission side of the second lens or with the near-emission side of the plate; The optical imaging system satisfies: 0.74≤R5 / d2m≤1.46; Wherein, R5 is the radius of curvature of the near-receiving side of the third lens, and d2m is the inner diameter of the near-emitting side of the second spacer element.

11. The optical imaging system according to claim 1 or 2, characterized in that, The optical imaging system satisfies: 1.81≤D0m / (TAN(Semi-FOV)*L)≤2.10; Wherein, D0m is the outer diameter of the near-emission side end face of the lens barrel, Semi-FOV is half of the maximum field of view of the optical imaging system, and L is the maximum height of the lens barrel.

12. The optical imaging system according to claim 1 or 2, characterized in that, The plurality of spacer elements includes: a third spacer element disposed on the near-emission side of the third lens and in at least partial contact with the near-emission side of the third lens; The optical imaging system satisfies: 12.08 ≤ D3m / CT4 ≤ 22.20; Wherein, D3m is the outer diameter of the near-emitting side of the third spacer element, and CT4 is the center thickness of the fourth lens.

13. The optical imaging system according to claim 1 or 2, characterized in that, The plurality of spacer elements includes: a third spacer element disposed on the near-emission side of the third lens and in at least partial contact with the near-emission side of the third lens; The optical imaging system satisfies: 1.23≤R7 / (D3m-d3m)≤3.30; Wherein, R7 is the radius of curvature of the near-receiving side of the fourth lens, D3m is the outer diameter of the near-emitting side of the third spacer element, and d3m is the inner diameter of the near-emitting side of the third spacer element.

Images