Optical system

Abstract

This application discloses an optical system comprising, sequentially from a first side to a second side, a first element group, a second element group, a third element group, and a fourth element group along an optical axis; the first element group includes a first lens, a reflective polarizing element, and a first quarter-wave plate; the second element group includes a second lens and a second quarter-wave plate; the third element group includes a third lens; and the fourth element group includes a fourth lens; wherein, the first side of the first lens is configured as a plane, and the reflective polarizing element and / or the first quarter-wave plate are attached to the first side of the first lens, and the on-axis distance TD from the first side of the first element group to the second side of the fourth element group satisfies the total effective focal length f of the optical system: TD / f < 1.5.

Description

Technical Field

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

[0002] As users' demand for virtual reality devices increases, higher requirements are also being placed on the optical systems in virtual reality devices. For example, the optical systems need to have high resolution and small size.

[0003] To ensure a small size for an optical system without affecting its field of view, two methods are typically employed. The first method is to reduce the viewing distance, meaning the user's eyes are closer to the system, causing eye strain and impacting user comfort. The second method involves increasing the number of lenses to guide reflected light to a smaller image plane. This increases manufacturing and assembly tolerances and the overall optical length. Furthermore, optical systems often have reflective polarizing elements or quarter-wave plates applied to curved surfaces. Due to the complexity of surface coating processes, the quality of these coatings deteriorates, resulting in a decrease in the overall performance of the optical system. Summary of the Invention

[0004] This application provides an optical system that can at least solve or partially solve at least one problem or other problems existing in the prior art.

[0005] One aspect of this application provides an optical system comprising, sequentially from a first side to a second side, a first element group, a second element group, a third element group, and a fourth element group along an optical axis; the first element group includes a first lens, a reflective polarizing element, and a first quarter-wave plate; the second element group includes a second lens and a second quarter-wave plate; the third element group includes a third lens; and the fourth element group includes a fourth lens; wherein, a first side surface of the first lens is configured as a plane, and the reflective polarizing element and / or the first quarter-wave plate is attached to the first side surface of the first lens, and the axial distance TD between the first side surface of the first element group and the second side surface of the fourth element group satisfies the following condition with respect to the total effective focal length f of the optical system: TD / f < 1.5.

[0006] According to an exemplary embodiment of this application, the center thickness CT3 of the third lens on the optical axis, the refractive index N2 of the second lens, the refractive index N3 of the third lens, and the air gap T23 between the second and third element groups on the optical axis satisfy: 8.0 <CT3 / ((N2+N3)×T23)<12.0。

[0007] According to an exemplary embodiment of this application, the center thickness CT2 of the second lens on the optical axis, the center thickness CT3 of the third lens on the optical axis, the air gap T23 between the second and third element groups on the optical axis, the dispersion coefficient V2 of the second lens, the dispersion coefficient V3 of the third lens, the effective focal length F2 of the second element group and the effective focal length F3 of the third element group satisfy: (T23+CT2+CT3)×(V2+V3) / |(F2+F3)|<10.0.

[0008] According to an exemplary embodiment of this application, the maximum field of view (FOV) of the optical system satisfies: 80° <FOV<120°。

[0009] According to an exemplary embodiment of this application, the radius of curvature R2 of the second side surface of the first lens, the center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, the air gap T12 between the first element group and the second element group on the optical axis, and the refractive index N1 of the first lens and the refractive index N2 of the second lens satisfy: -3.0 <R2 / ((CT1+T12+CT2)×(N1+N2))<0。

[0010] According to an exemplary embodiment of this application, the radius of curvature R5 of the first side surface of the third lens and the radius of curvature R6 of the second side surface of the third lens satisfy: 0.2 < (R5-R6) / (R5+R6) < 1.5.

[0011] According to an exemplary embodiment of this application, the radius of curvature R7 of the first side surface of the fourth lens, the radius of curvature R8 of the second side surface of the fourth lens, and the effective focal length F4 of the fourth element group satisfy: 0 <F4 / R7-F4 / R8<2.0。

[0012] According to an exemplary embodiment of this application, the radius of curvature R6 of the second side of the third lens, the radius of curvature R8 of the second side of the fourth lens, the center thickness CT3 of the third lens on the optical axis, the center thickness CT4 of the fourth lens on the optical axis, and the air gap T34 of the third element group and the fourth element group on the optical axis satisfy: -15.0<(R6-R8) / (CT3+T34+CT4)<0.

[0013] According to an exemplary embodiment of this application, the dispersion coefficient V3 of the third lens, the dispersion coefficient V4 of the fourth lens, the center thickness CT3 of the third lens on the optical axis, the center thickness CT4 of the fourth lens on the optical axis, the effective focal length F3 of the third element group and the effective focal length F4 of the fourth element group satisfy: 2.0 < (V3×CT3+V4×CT4) / (F3+F4) < 6.5.

[0014] According to an exemplary embodiment of this application, the on-axis distance TD between the first side of the first element group and the second side of the fourth element group, the maximum field of view (FOV) of the optical system, and the total effective focal length (f) of the optical system satisfy: 0.5 <TD / (tan(FOV / 2)×f)<1.5。

[0015] According to an exemplary embodiment of this application, the radius of curvature R5 of the first side surface of the third lens, the radius of curvature R6 of the second side surface of the third lens, and the effective focal length F3 of the third element group satisfy: 2.0 < |R5 + R6| / F3.

[0016] According to an exemplary embodiment of this application, the effective focal length F3 of the third element group, the effective focal length F4 of the fourth lens group, the air gap T34 between the third and fourth element groups on the optical axis, the refractive index N3 of the third lens, the refractive index N4 of the fourth lens, and the total effective focal length f of the optical system satisfy: 0.2mm < (F3×T34 / N3 + F4×T34 / N4) / f < 2.0mm.

[0017] According to an exemplary embodiment of this application, the effective focal length F1 of the first element group and the total effective focal length f of the optical system satisfy: F1 / f < 2.0.

[0018] According to an exemplary embodiment of this application, the effective focal length F3 of the third element group and the total effective focal length f of the optical system satisfy: 0 <F3 / f<20.0。

[0019] According to an exemplary embodiment of this application, the effective focal length F4 of the fourth element group and the total effective focal length f of the optical system satisfy: 0 <F4 / f<10.0。

[0020] According to an exemplary embodiment of this application, the center thickness CTR of the reflective polarizing element on the optical axis, the center thickness CTQ1 of the first quarter-wave plate on the optical axis, the center thickness CT1 of the first lens on the optical axis, the dispersion coefficient VR of the reflective polarizing element, the dispersion coefficient VQ1 of the first quarter-wave plate, the dispersion coefficient V1 of the first lens, and the effective focal length F1 of the first element group satisfy: 40.0 < (CTR + CTQ1 + CT1) × (VR + VQ1 + V1) / F1 < 70.0.

[0021] According to an exemplary embodiment of this application, the refractive index NR of the reflective polarizing element, the refractive index NQ1 of the first quarter-wave plate, the refractive index N1 of the first lens, the refractive index N2 of the second lens, the radius of curvature R2 of the second side surface of the first lens, and the effective focal length F1 of the first element group satisfy: -5.0<(NR+NQ1)×R2 / ((N1+N2)×F1)<0.

[0022] According to an exemplary embodiment of this application, the maximum effective half-aperture DT31 of the first side of the third lens, the maximum effective half-aperture DT42 of the second side of the fourth lens, the radius of curvature R6 of the second side of the third lens, and the radius of curvature R8 of the second side of the fourth lens satisfy: (DT31+DT42) / |(R6+R8)|<1.0.

[0023] According to an exemplary embodiment of this application, the radius of curvature R2 of the second side surface of the first lens, the maximum effective half-aperture DT12 of the second side surface of the first lens, and the maximum effective half-aperture DT21 of the first side surface of the second lens satisfy: -2.0 <R2 / (DT12+DT21)<-1.0。

[0024] According to an exemplary embodiment of this application, a partial reflective layer is provided on the second side of the first lens, and the first or second side of the second lens is configured as a plane.

[0025] The optical system provided in this application is configured as a folding optical system, which uses a planar film to attach the reflective polarizing element and / or the first quarter-wave plate to a plane. This ensures the quality of the reflective polarizing element and / or the first quarter-wave plate after attachment, thus guaranteeing system performance. At the same time, by constraining the ratio of the on-axis distance from the first side of the first element group to the second side of the fourth element group to the total effective focal length of the optical system and making the ratio less than 1.5, the optical system can be guaranteed to have a reasonable focal length and a small size as much as possible. Furthermore, the configuration of the above-mentioned structures optimizes the external field of view performance of the optical system. Attached Figure Description

[0026] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0027] Figure 1 A schematic diagram of the structure of the optical system according to this application is shown;

[0028] Figure 2 It shows Figure 1 A magnified view of region I;

[0029] Figure 3 A schematic diagram of the structure of the optical system according to Embodiment 1 of this application is shown;

[0030] Figures 4A to 4C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 1 of this application are shown respectively.

[0031] Figure 5 A schematic diagram of the structure of the optical system according to Embodiment 2 of this application is shown;

[0032] Figures 6A to 6C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 2 of this application are shown respectively.

[0033] Figure 7 A schematic diagram of the structure of the optical system according to Embodiment 3 of this application is shown;

[0034] Figures 8A to 8C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 3 of this application are shown respectively.

[0035] Figure 9 A schematic diagram of the structure of the optical system according to Embodiment 4 of this application is shown;

[0036] Figures 10A to 10C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 4 of this application are shown respectively.

[0037] Figure 11 A schematic diagram of the structure of the optical system according to Embodiment 5 of this application is shown;

[0038] Figures 12A to 12C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 5 of this application are shown respectively.

[0039] Figure 13 A schematic diagram of the structure of the optical system according to Embodiment 6 of this application is shown;

[0040] Figures 14A to 14C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 6 of this application are shown respectively.

[0041] Figure 15 A schematic diagram of the structure of the optical system according to Embodiment 7 of this application is shown;

[0042] Figures 16A to 16C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 7 of this application are shown respectively.

[0043] Figure 17 A schematic diagram of the structure of the optical system according to Embodiment 8 of this application is shown; and

[0044] Figures 18A to 18C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 8 of this application are shown respectively. Detailed Implementation

[0045] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements.

[0046] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0047] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not drawn strictly to scale.

[0048] In this paper, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the first side (e.g., the human eye side) is called the first side surface of the lens, and the surface of each lens closest to the second side (e.g., the display side) is called the second side surface of the lens.

[0049] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising" as used in this specification indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0050] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized sense, unless expressly so specified herein.

[0051] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0052] The features, principles and other aspects of this application are described in detail below.

[0053] refer to Figure 1 and Figure 2 The first aspect of this application provides an optical system that may include a first element group, a second element group, a third element group, and a fourth element group arranged sequentially along an optical axis from a first side to a second side. The first element group may, for example, include a first lens, a reflective polarizing element, and a first quarter-wave plate. The second element group may, for example, include a second lens and a second quarter-wave plate. The third element group may, for example, include a third lens. The fourth element group may, for example, include a fourth lens. Air gaps may exist between adjacent element groups in the first to fourth element groups.

[0054] In an exemplary embodiment, the first side may be, for example, the eye side, and the second side may be, for example, the display side. Accordingly, the first side of each element (first lens, second lens, third lens, fourth lens, reflective polarizing element, first quarter-wave plate, second quarter-wave plate) may be referred to as the eye-side side, and the second side may be referred to as the display-side side.

[0055] In an exemplary embodiment, the optical system may further include an aperture stop, which may be disposed, for example, between the first side and the first lens. The image light on the display is finally projected to the user's eye after being refracted and reflected multiple times by the fourth lens, the third lens, the second lens, the second quarter-wave plate, the first lens, the first quarter-wave plate, and the reflective polarizing element.

[0056] In an exemplary embodiment, an image surface may be provided on the second side of the optical system, and the image surface may, for example, be a display. Image light from the display sequentially passes through a fourth lens, a third lens, a second lens, a second quarter-wave plate, a first lens, and a first quarter-wave plate, reaching a reflective polarizing element, and is then reflected at the reflective polarizing element to form first reflected image light. The first reflected image light passes through the first quarter-wave plate and the first lens and reaches a partial reflective layer, and is then reflected at the partial reflective layer to form second reflected image light. The second reflected image light sequentially passes through the first lens, the first quarter-wave plate, and the reflective polarizing element to the aperture stop and is finally projected into the user's eye. In other examples, the order in which the image light passes through the second lens and the second quarter-wave plate during the formation of the first reflected image light can be interchanged. The optical system provided in this application effectively shortens the overall length of the optical system by folding the required optical path through a combination of light reflection and refraction without affecting the projection quality.

[0057] In an exemplary embodiment, the first side surface of the first lens is configured as a plane, and the reflective polarizing element and / or the first quarter-wave plate are attached to the first side surface of the first lens. Adopting the method of planar film sticking to attach the reflective polarizing element and / or the first quarter-wave plate on the plane can ensure the quality after the attachment of the reflective polarizing element and / or the first quarter-wave plate, thereby improving the off-axis field performance of the optical system.

[0058] As an example, the reflective polarizing element is attached to the first quarter-wave plate to form a film layer, and the film layer after attachment is attached to the first side surface of the first lens, wherein the reflective polarizing element is located on the first side surface of the first quarter-wave plate. By combining the reflective polarizing element and the first quarter-wave plate together to form a film layer, the number of attachment surfaces of the film layer can be reduced, and the attachment yield rate of the film layer can be improved. And the film layer after combination is attached to the plane, which is beneficial to improving the stability after the attachment of the film layer, thereby improving the off-axis field performance of the optical system.

[0059] As an example, the first side surface or the second side surface of the second lens is configured as a plane, and a second quarter-wave plate is provided on the side surface of the second lens configured as a plane. The optical system provided by the present application can improve the off-axis field performance of the optical system by making the first lens to the fourth lens have two planes and combining with the aspherical designs of the third lens and the fourth lens.

[0060] In an exemplary embodiment, the optical system may further include a partial reflection layer, and the partial reflection layer can be attached to, for example, the second side surface of the first lens. The partial reflection layer has a semi-transmissive and semi-reflective effect on light. By providing the partial reflection layer on the second side surface of the first lens and combining with the reflective polarizing element and the first quarter-wave plate on the first side surface of the first lens, the light can be made to折返 multiple times, effectively reducing the body length of the optical system.

[0061] In an exemplary embodiment, the on-axis distance TD from the first side surface of the first element group to the second side surface of the fourth element group and the total effective focal length f of the optical system may satisfy: TD / f < 1.5. In the example, 0.8 < TD / f < 1.3. By constraining the ratio of the on-axis distance from the first side surface of the first element group to the second side surface of the fourth element group to the total effective focal length of the optical system and making the above ratio less than 1.5, it is possible to ensure that the optical system has a reasonable focal length and a small size as much as possible, which is beneficial to the miniaturization of the optical system.

[0062] In an exemplary embodiment, the central thickness CT3 of the third lens on the optical axis, the refractive index N2 of the second lens, the refractive index N3 of the third lens, and the air gap T23 between the second element group and the third element group on the optical axis may satisfy: 8.0 < CT3 / ((N2 + N3) × T23) < 12.0. By making the third lens have a reasonable thickness and combining it with a reasonable refractive index of the second lens, a reasonable refractive index of the third lens, and a reasonable air gap between the second element group and the third element group on the optical axis, it is possible to ensure that the optical system has a reasonable focal length and is beneficial to shortening the body length of the optical system, thereby ensuring the miniaturization of the optical system.

[0063] In an exemplary embodiment, the central thickness CT2 of the second lens on the optical axis, the central thickness CT3 of the third lens on the optical axis, the air gap T23 between the second element group and the third element group on the optical axis, the dispersion coefficient V2 of the second lens, the dispersion coefficient V3 of the third lens, the effective focal length F2 of the second element group, and the effective focal length F3 of the third element group may satisfy: (T23 + CT2 + CT3) × (V2 + V3) / |(F2 + F3)| < 10.0. By controlling the above conditional formula, it is possible to ensure that the optical system has a smaller body length and a reasonable focal length, and at the same time, by combining reasonable dispersion coefficients of the second lens and the third lens, the chromatic aberration of the optical system can be reduced, and the light transmission ability of the optical system in multiple bands can be improved.

[0064] In an exemplary embodiment, the maximum field of view FOV of the optical system may satisfy: 80° < FOV < 120°. By restricting the maximum field of view of the optical system and making the maximum field of view within the range of 80° to 120°, it is possible to ensure that the user has a good experience and that the optical system has good imaging performance.

[0065] In an exemplary embodiment, the radius of curvature R2 of the second side of the first lens, the central thickness CT1 of the first lens on the optical axis, the central thickness CT2 of the second lens on the optical axis, the air gap T12 between the first element group and the second element group on the optical axis, the refractive index N1 of the first lens, and the refractive index N2 of the second lens may satisfy: -3.0 < R2 / ((CT1 + T12 + CT2) × (N1 + N2)) < 0. By controlling the above conditional formula, it is possible to make the radius of curvature of the second side of the first lens within a reasonable range, ensure that this side has good light convergence when reflecting light, and improve the light convergence ability of the optical system for large field of view light; at the same time, it can also ensure that the optical system has a smaller body length, which is beneficial to the miniaturization of the optical system.

[0066] In an exemplary embodiment, the radius of curvature R5 of the first side surface of the third lens and the radius of curvature R6 of the second side surface of the third lens may satisfy: 0.2 < (R5 - R6) / (R5 + R6) < 1.5. In an example, 0.5 < (R5 - R6) / (R5 + R6) < 1.1. By constraining the radii of curvature of the first side surface and the second side surface of the third lens and making the radii of curvature of both side surfaces relatively large, the sensitivity of one side surface can be ensured and the processing difficulty of the third lens can be reduced.

[0067] In an exemplary embodiment, the radius of curvature R7 of the first side surface of the fourth lens, the radius of curvature R8 of the second side surface of the fourth lens, and the effective focal length F4 of the fourth lens group may satisfy: 0 < F4 / R7 - F4 / R8 < 2.0. In an example, 1.4 < F4 / R7 - F4 / R8 < 1.98. By constraining the ratios of the effective focal length of the fourth lens group to the radii of curvature of the two side surfaces of the fourth lens, the sensitivity of the fourth lens can be reduced, and thus the processing difficulty of the fourth lens can be reduced.

[0068] In an exemplary embodiment, the radius of curvature R6 of the second side surface of the third lens, the radius of curvature R8 of the second side surface of the fourth lens, the central thickness CT3 of the third lens on the optical axis, the central thickness CT4 of the fourth lens on the optical axis, and the air gap T34 between the third lens group and the fourth lens group on the optical axis may satisfy: -15.0 < (R6 - R8) / (CT3 + T34 + CT4) < 0. By controlling the above conditional expression, the sensitivities of the third lens and the fourth lens and the body length of the optical system can be effectively controlled, ensuring the miniaturization of the optical system and good processability.

[0069] In an exemplary embodiment, the dispersion coefficient V3 of the third lens, the dispersion coefficient V4 of the fourth lens, the central thickness CT3 of the third lens on the optical axis, the central thickness CT4 of the fourth lens on the optical axis, the effective focal length F3 of the third lens group, and the effective focal length F4 of the fourth lens group may satisfy: 2.0 < (V3×CT3 + V4×CT4) / (F3 + F4) < 6.5. By controlling the above conditional expression, the dispersion coefficients of the third lens and the fourth lens can be reasonably distributed, which is beneficial to correcting the chromatic aberration of the optical system; at the same time, the focal lengths of the third lens and the fourth lens can also be constrained, which is beneficial to reducing the sensitivity of the optical system and improving the performance yield of the optical system.

[0070] In an exemplary embodiment, the axial distance TD from the first side of the first element group to the second side of the fourth element group, the maximum field of view angle FOV of the optical system, and the total effective focal length f of the optical system may satisfy: 0.5 < TD / (tan(FOV / 2) × f) < 1.5. By controlling the above conditional expression, the total optical length and the corresponding image height of the optical system can be within reasonable ranges, thereby ensuring that the optical system simultaneously satisfies the characteristics of miniaturization and small image height.

[0071] In an exemplary embodiment, the radius of curvature R5 of the first side of the third lens, the radius of curvature R6 of the second side of the third lens, and the effective focal length F3 of the third element group may satisfy: 2.0 < |R5 + R6| / F3. In an example, 2.0 < |R5 + R6| / F3 < 833.0, and further, 10.0 < |R5 + R6| / F3 < 80.0. By restricting the ratio of the sum of the radii of curvature of the first and second sides of the third lens to the effective focal length of the third element group within a certain range, the sensitivity of the third lens can be reduced, and further the processing difficulty of the third lens can be lowered.

[0072] In an exemplary embodiment, the effective focal length F3 of the third element group, the effective focal length F4 of the fourth lens group, the air gap T34 between the third element group and the fourth lens group on the optical axis, the refractive index N3 of the third lens, the refractive index N4 of the fourth lens, and the total effective focal length f of the optical system may satisfy: 0.2 mm < (F3 × T34 / N3 + F4 × T34 / N4) / f < 2.0 mm. In an example, 0.5 mm ≤ (F3 × T34 / N3 + F4 × T34 / N4) / f < 1.6 mm. By controlling the above conditional expression, the optical power of the optical system can be reasonably distributed, and with a reasonable air gap between the third element group and the fourth lens group on the optical axis, it is beneficial to reduce the sensitivity of the optical system and improve the performance yield of the optical system.

[0073] In an exemplary embodiment, the effective focal length F1 of the first element group and the total effective focal length f of the optical system may satisfy: F1 / f < 2.0. In an example, 0.5 < F1 / f < 1.5. By restricting the ratio of the effective focal length of the first element group to the total effective focal length of the optical system, it is beneficial to reasonably distribute the optical power of the optical system, and further ensure that the first lens has a large light bending ability.

[0074] In an exemplary embodiment, the effective focal length F3 of the third element group and the total effective focal length f of the optical system may satisfy: 0 < F3 / f < 20.0. In an example, 1.0 < F3 / f < 15.0. By restricting the ratio of the effective focal length of the third element group to the total effective focal length of the optical system, it is beneficial to reasonably distribute the optical power of the optical system, and further ensure that the third lens has a good light transition ability.

[0075] In an exemplary embodiment, the effective focal length F4 of the fourth element group and the total effective focal length f of the optical system may satisfy: 0 < F4 / f < 10.0. In an example, 1.0 < F4 / f < 6.0. By constraining the ratio of the effective focal length of the fourth element group to the total effective focal length of the optical system, it is beneficial to reasonably distribute the optical power of the optical system, and further ensure that the fourth lens has good light transition ability.

[0076] In an exemplary embodiment, the central thickness CTR of the reflective polarizing element on the optical axis, the central thickness CTQ1 of the first quarter-wave plate on the optical axis, the central thickness CT1 of the first lens on the optical axis, the dispersion coefficient VR of the reflective polarizing element, the dispersion coefficient VQ1 of the first quarter-wave plate, the dispersion coefficient V1 of the first lens, and the effective focal length F1 of the first element group may satisfy: 40.0 < (CTR + CTQ1 + CT1) × (VR + VQ1 + V1) / F1 < 70.0. By reasonably configuring the central thicknesses of the reflective polarizing element, the first quarter-wave plate, and the first lens on the optical axis, and making the ratio of the sum of the central thicknesses of the reflective polarizing element, the first quarter-wave plate, and the first lens on the optical axis to the effective focal length of the first element group within a certain range, the focal length of the optical system can be effectively constrained.

[0077] In an exemplary embodiment, the refractive index NR of the reflective polarizing element, the refractive index NQ1 of the first quarter-wave plate, the refractive index N1 of the first lens, the refractive index N2 of the second lens, the curvature radius R2 of the second side surface of the first lens, and the effective focal length F1 of the first element group may satisfy: -5.0 < (NR + NQ1) × R2 / ((N1 + N2) × F1) < 0. By controlling the above conditional expression, it is beneficial to reduce the incident angle of light on the first quarter-wave plate and the reflective polarizing element, and further reduce the angular effect of the first quarter-wave plate.

[0078] In an exemplary embodiment, the maximum effective semi-aperture DT31 of the first side surface of the third lens, the maximum effective semi-aperture DT42 of the second side surface of the fourth lens, the curvature radius R6 of the second side surface of the third lens, and the curvature radius R8 of the second side surface of the fourth lens may satisfy: (DT31 + DT42) / |(R6 + R8)| < 1.0. By controlling the above conditional expression, the maximum effective semi-aperture of the first side surface of the third lens and the maximum effective semi-aperture of the second side surface of the fourth lens can be constrained, and further the field angle of the optical system can be limited. At the same time, with reasonable curvature radii of the second side surfaces of the third lens and the fourth lens, the third lens and the fourth lens have reasonable optical power and good forming ability, reducing the forming difficulty of the optical system.

[0079] In an exemplary embodiment, the radius of curvature R2 of the second side surface of the first lens, the maximum effective semi-aperture DT12 of the second side surface of the first lens, and the maximum effective semi-aperture DT21 of the first side surface of the second lens may satisfy: -2.0 < R2 / (DT12 + DT21) < -1.0. By controlling the above conditional expression, it is possible to constrain the optical power of the first lens, the maximum effective semi-aperture of the second side surface of the first lens, and the maximum effective semi-aperture of the second lens, and further limit the field angle of the optical system, ensuring that the optical system has a first lens with a relatively large field angle and good light-gathering ability.

[0080] The optical system according to the above embodiment of the present application may employ multiple lenses, such as the four lenses described above. By reasonably allocating the parameters of the reflective polarizing element, the first quarter-wave plate, and each lens, it is possible to reduce the body length of the optical system, improve the processability and imaging quality of the optical system. The optical system configured as above has characteristics such as miniaturization, low sensitivity, and good imaging quality, and can well meet the usage requirements of various portable electronic products in the projection scenario.

[0081] In an embodiment of the present application, at least one of the lens surfaces of each of the first lens to the fourth lens is an aspherical lens surface. The characteristic of an aspherical lens is that the curvature continuously changes from the center of the lens to the periphery of the lens. Different from a spherical lens with a constant curvature from the center of the lens to the periphery, an aspherical lens has better radius of curvature characteristics and has the advantages of improving distortion aberration and improving astigmatism aberration. After using an aspherical lens, it is possible to eliminate the aberration that appears during imaging as much as possible, and thus improve the imaging quality.

[0082] However, those skilled in the art should understand that without departing from the technical solution claimed in the present application, the number of lenses constituting the optical system can be changed to obtain the various results and advantages described in this specification.

[0083] Reference Figure 1 and Figure 2 , the second aspect of the present application provides such an optical system, which may include a first element group, a second element group, a third element group, and a fourth element group arranged in sequence along the optical axis from the first side to the second side. The first element group may include, for example, a first lens, a reflective polarizing element, and a first quarter-wave plate. The second element group may include, for example, a second lens and a second quarter-wave plate. The third element group may include, for example, a third lens. The fourth element group may include, for example, a fourth lens. There may be an air gap between adjacent element groups among the first element group to the fourth element group.

[0084] Among them, the first side surface of the first lens is configured as a plane, and the reflective polarizing element and / or the first quarter-wave plate are attached to the first side surface of the first lens. The on-axis distance TD from the first side surface of the first element group to the second side surface of the fourth element group, the maximum field angle FOV of the optical system, and the total effective focal length f of the optical system can satisfy: 0.5 < TD / (tan(FOV / 2) × f) < 1.5. The optical system provided in this application uses the method of planar film sticking to attach the reflective polarizing element and / or the first quarter-wave plate on the plane, which can ensure the quality of the reflective polarizing element and / or the first quarter-wave plate after attachment, guarantee the system performance. At the same time, by restricting the on-axis distance from the first side surface of the first element group to the second side surface of the fourth element group, the maximum field angle of the optical system, and the total effective focal length of the optical system, the optical total length and the corresponding image height of the optical system are respectively within a reasonable range, so as to ensure that the optical system simultaneously meets the characteristics of miniaturization and small image height.

[0085] Reference Figure 1 and Figure 2 , a third aspect of this application provides such an optical system, which may include a first element group, a second element group, a third element group, and a fourth element group arranged in sequence along the optical axis from the first side to the second side. The first element group may, for example, include a first lens, a reflective polarizing element, and a first quarter-wave plate. The second element group may, for example, include a second lens and a second quarter-wave plate. The third element group may, for example, include a third lens. The fourth element group may, for example, include a fourth lens. There may be an air gap between adjacent element groups among the first element group to the fourth element group.

[0086] Among them, the first side surface of the first lens is configured as a plane, and the reflective polarizing element and / or the first quarter-wave plate are attached to the first side surface of the first lens. The curvature radius R6 of the second side surface of the third lens, the curvature radius R8 of the second side surface of the fourth lens, the central thickness CT3 of the third lens on the optical axis, the central thickness CT4 of the fourth lens on the optical axis, and the air gap T34 between the third element group and the fourth element group on the optical axis can satisfy: -15.0 < (R6 - R8) / (CT3 + T34 + CT4) < 0. The optical system provided in this application uses the method of planar film sticking to attach the reflective polarizing element and / or the first quarter-wave plate on the plane, which can ensure the quality of the reflective polarizing element and / or the first quarter-wave plate after attachment, guarantee the system performance. At the same time, by restricting the central thickness and surface shape of the third lens and the fourth lens and the on-axis spacing between the third element group and the fourth element group, the sensitivity of the third lens and the fourth lens and the body length of the optical system can be effectively controlled, ensuring the miniaturization of the optical system and good processability.

[0087] Specific embodiments of the optical system applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

[0088] Example 1

[0089] The following is for reference Figures 3 to 4C The optical system according to Embodiment 1 of this application is described.

[0090] like Figure 3 As shown, the optical system 100 includes a first element group, a second element group, a third element group, and a fourth element group arranged sequentially along the optical axis from a first side to a second side. The first element group includes a first lens E1, a reflective polarizing element RP, and a first quarter-wave plate QWP1. In other examples, the first element group also includes a partial reflective layer BS (not shown). The second element group includes a second lens E2 and a second quarter-wave plate QWP2. The third element group includes a third lens E3. The fourth element group includes a fourth lens E4. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, fourth lens E4, reflective polarizing element RP, first quarter-wave plate QWP1, and second quarter-wave plate QWP2) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0091] The first lens E1 has positive optical power. Its side near the human eye (S3) is flat, and its side near the display (S4) is convex, with a partial reflective layer (BS) attached. The reflective polarizing element RP has a side near the human eye (S1) and a side near the display. The first quarter-wave plate QWP1 has a side near the human eye (S2) and a side near the display. The side near the display of the reflective polarizing element RP is attached to the side near the human eye (S2) of the first quarter-wave plate QWP1, and the side near the display of the first quarter-wave plate QWP1 is attached to the side near the human eye (S3) of the first lens E1. The second lens E2 has negative optical power. Its side near the human eye (S6) is flat, and its side near the display (S7) is concave. The second quarter-wave plate QWP2 has a side near the human eye (S5) and a side near the display, with its side near the display attached to the side near the human eye (S6) of the second lens E2. The third lens E3 has positive optical power. Its side near the human eye (S8) is concave, and its side near the display (S9) is convex. The fourth lens E4 has positive optical power, and its side S10 near the human eye is convex, while its side S11 near the display screen is convex.

[0092] In this example, an image surface S14 may be provided on the second side of the optical system, and the image surface S14 may, for example, be a display. The optical system also includes a third quarter-wave plate QWP3, which has a near-eye side S12 and a near-display side, with the near-display side attached to the near-eye side S13 of the display. Image light from the display sequentially passes through a fourth lens E4, a third lens E3, a second lens E2, a second quarter-wave plate QWP2, a first lens E1, and a first quarter-wave plate QWP1, and reaches a reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the first quarter-wave plate QWP1 and the first lens E1, and reaches a partial reflective layer BS, where it undergoes a second reflection. The light after the second reflection sequentially passes through the first lens E1, the first quarter-wave plate QWP1, and the reflective polarizing element RP, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system, after two reflections, is finally projected into the user's eye.

[0093] Table 1 shows the basic parameters of the optical system of Embodiment 1, where the units for radius of curvature and thickness / distance are millimeters (mm). Image light from the display passes through the elements in the order of number 20 to number 2 and is finally projected into the human eye.

[0094]

[0095] Table 1

[0096] In Embodiment 1, the near-display side S4 of the first lens E1, the near-display side S7 of the second lens E2, the near-eye side S8 and the near-display side S9 of the third lens E3, and the near-eye side S10 and the near-display side S11 of the fourth lens E4 are all aspherical. The surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0097]

[0098] Where x is the distance vector from the vertex of the aspherical surface at a height of h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 2 gives the higher-order coefficients A4, A6, A8, A11 that can be used for each aspherical mirror S4, S7-S11 in Example 1. 10 A 12 A 14 A 16 A 18 A 20 A 22 A24 A 26 A 28 and A 30 .

[0099] Face number A4 A6 A8 A10 A12 A14 A16 S4 4.3289E-01 2.1686E-02 -2.7449E-02 -4.8581E-03 2.0575E-03 5.2862E-04 1.5030E-04 S7 2.4267E+00 -2.4943E+00 8.6225E-01 -1.1198E-01 -1.8058E-02 -3.1086E-02 1.1422E-02 S8 4.9071E+00 -1.9923E+00 6.8425E-01 -2.4305E-01 3.5534E-02 -2.3509E-02 3.3611E-03 S9 1.8891E+00 7.7453E-02 -1.6507E-02 -9.4373E-02 4.5184E-02 1.8369E-03 1.5274E-02 S10 -3.1246E+00 6.0112E-01 2.5996E-01 2.3939E-01 -1.0799E-01 -8.8038E-02 -1.0118E-02 S11 7.4799E+00 -7.7532E-01 5.5241E-01 -5.6028E-01 1.6354E-01 -1.4244E-01 1.4115E-01 Face number A18 A20 A22 A24 A26 A28 A30 S4 -6.7556E-04 -2.1901E-04 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S7 -6.1916E-03 1.4864E-03 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S8 -6.0415E-04 1.2443E-02 1.0360E-03 -1.9227E-03 4.2187E-04 -1.1550E-03 4.1301E-04 S9 5.4147E-02 3.1070E-02 -1.6282E-02 -3.0189E-02 -1.3440E-02 1.3696E-02 -9.4971E-04 S10 8.0983E-02 7.1610E-02 -3.4167E-02 -7.3737E-02 -2.7814E-02 7.1817E-02 2.8273E-02 S11 -8.4386E-02 7.9492E-02 -5.5573E-02 3.8649E-02 -4.1101E-02 2.6123E-02 -6.0879E-03

[0100] Table 2

[0101] Figure 4A The on-axis chromatic aberration curve of the optical system 100 of Embodiment 1 is shown, which represents the deflection of the focal point of light of different wavelengths after passing through the optical system 100. Figure 4B The astigmatism curves of the optical system 100 of Embodiment 1 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field of view angles. Figure 4C The distortion curves of the optical system 100 of Embodiment 1 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 4A to 4C It can be seen that the optical system 100 given in Example 1 can achieve good imaging quality.

[0102] Example 2

[0103] The following is for reference Figures 5 to 6C The optical system according to Embodiment 2 of this application is described.

[0104] like Figure 5 As shown, the optical system 200 includes a first element group, a second element group, a third element group, and a fourth element group arranged sequentially along the optical axis from a first side to a second side. The first element group includes a first lens E1, a reflective polarizing element RP, and a first quarter-wave plate QWP1. In other examples, the first element group also includes a partial reflective layer BS (not shown). The second element group includes a second lens E2 and a second quarter-wave plate QWP2. The third element group includes a third lens E3. The fourth element group includes a fourth lens E4. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, fourth lens E4, reflective polarizing element RP, first quarter-wave plate QWP1, and second quarter-wave plate QWP2) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0105] The first lens E1 has positive optical power. Its side near the human eye (S3) is flat, and its side near the display (S4) is convex, with a partial reflective layer (BS) attached. The reflective polarizing element RP has a side near the human eye (S1) and a side near the display. The first quarter-wave plate QWP1 has a side near the human eye (S2) and a side near the display. The side near the display of the reflective polarizing element RP is attached to the side near the human eye (S2) of the first quarter-wave plate QWP1, and the side near the display of the first quarter-wave plate QWP1 is attached to the side near the human eye (S3) of the first lens E1. The second lens E2 has positive optical power. Its side near the human eye (S6) is flat, and its side near the display (S7) is convex. The second quarter-wave plate QWP2 has a side near the human eye (S5) and a side near the display, with its side near the display attached to the side near the human eye (S6) of the second lens E2. The third lens E3 has positive optical power. Its side near the human eye (S8) is concave, and its side near the display (S9) is convex. The fourth lens E4 has positive optical power, and its side S10 near the human eye is convex, while its side S11 near the display screen is convex.

[0106] In this example, an image surface S14 may be provided on the second side of the optical system, and the image surface S14 may, for example, be a display. The optical system also includes a third quarter-wave plate QWP3, which has a near-eye side S12 and a near-display side, with the near-display side attached to the near-eye side S13 of the display. Image light from the display sequentially passes through a fourth lens E4, a third lens E3, a second lens E2, a second quarter-wave plate QWP2, a first lens E1, and a first quarter-wave plate QWP1, and reaches a reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the first quarter-wave plate QWP1 and the first lens E1, and reaches a partial reflective layer BS, where it undergoes a second reflection. The light after the second reflection sequentially passes through the first lens E1, the first quarter-wave plate QWP1, and the reflective polarizing element RP, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system, after two reflections, is finally projected into the user's eye.

[0107] Table 3 shows the basic parameters of the optical system in Example 2, where the units for radius of curvature and thickness / distance are millimeters (mm). The image light from the display passes through each element in the order of number 20 to number 2 and is finally projected into the human eye.

[0108]

[0109]

[0110] Table 3

[0111] In Example 2, the near-display side S4 of the first lens E1, the near-display side S7 of the second lens E2, the near-eye side S8 and the near-display side S9 of the third lens E3, and the near-eye side S10 and the near-display side S11 of the fourth lens E4 are all aspherical. Table 4 shows the higher-order coefficients A4, A6, A8, and A11 that can be used for each aspherical mirror S4, S7-S11 in Example 2. 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 and A 30 .

[0112] Face number A4 A6 A8 A10 A12 A14 A16 S4 3.9555E-01 3.7287E-02 -2.4101E-02 -1.4503E-02 4.6114E-03 4.8805E-03 -2.8605E-04 S7 3.1277E+00 -2.5677E+00 9.4615E-01 1.2429E-01 1.6759E-03 -1.3656E-01 2.4581E-02 S8 5.8898E+00 -2.2942E+00 7.3693E-01 -6.0315E-02 9.5809E-02 -9.7918E-02 -2.1595E-02 S9 1.1168E+00 7.9603E-01 -2.3175E-01 -3.3070E-02 -2.7022E-01 1.9470E-01 -2.9293E-02 S10 -2.0619E+00 1.6416E+00 -3.2770E-01 1.4145E-01 -1.1040E-01 1.5952E-01 -1.6915E-01 S11 6.7642E+00 -5.3485E-01 5.1734E-01 -7.7158E-01 2.4953E-01 -6.6325E-02 1.3609E-01 Face number A18 A20 A22 A24 A26 A28 A30 S4 -2.0882E-03 -1.2222E-05 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S7 2.8595E-02 -3.3633E-02 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S8 -6.8980E-03 -9.3528E-03 4.5942E-02 1.8782E-02 -1.1745E-02 -6.2689E-03 -7.8181E-04 S9 7.0963E-02 -4.2115E-02 1.0170E-01 -1.1081E-01 -5.8776E-03 2.7192E-02 -2.9826E-03 S10 4.9438E-02 3.3150E-02 9.3164E-02 -1.4933E-01 -4.7679E-02 7.0198E-02 8.0849E-03 S11 -1.6638E-01 5.5732E-02 4.9848E-02 2.3440E-02 -7.7809E-02 2.7819E-02 1.3856E-03

[0113] Table 4

[0114] Figure 6A The on-axis chromatic aberration curve of the optical system 200 of Embodiment 2 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the optical system 200. Figure 6B The astigmatism curves of the optical system 200 of Embodiment 2 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field of view angles. Figure 6C The distortion curves of the optical system 200 of Embodiment 2 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 6A to 6C It can be seen that the optical system 200 given in Example 2 can achieve good imaging quality.

[0115] Example 3

[0116] The following is for reference Figures 7 to 8C The optical system according to Embodiment 3 of this application is described.

[0117] like Figure 7As shown, the optical system 300 includes a first element group, a second element group, a third element group, and a fourth element group arranged sequentially along the optical axis from a first side to a second side. The first element group includes a first lens E1, a reflective polarizing element RP, and a first quarter-wave plate QWP1. In other examples, the first element group also includes a partial reflective layer BS (not shown). The second element group includes a second lens E2 and a second quarter-wave plate QWP2. The third element group includes a third lens E3. The fourth element group includes a fourth lens E4. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, fourth lens E4, reflective polarizing element RP, first quarter-wave plate QWP1, and second quarter-wave plate QWP2) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0118] The first lens E1 has positive optical power. Its side near the human eye (S3) is flat, and its side near the display (S4) is convex, with a partial reflective layer (BS) attached. The reflective polarizing element RP has a side near the human eye (S1) and a side near the display. The first quarter-wave plate QWP1 has a side near the human eye (S2) and a side near the display. The side near the display of the reflective polarizing element RP is attached to the side near the human eye (S2) of the first quarter-wave plate QWP1, and the side near the display of the first quarter-wave plate QWP1 is attached to the side near the human eye (S3) of the first lens E1. The second lens E2 has negative optical power. Its side near the human eye (S6) is flat, and its side near the display (S7) is concave. The second quarter-wave plate QWP2 has a side near the human eye (S5) and a side near the display, with its side near the display attached to the side near the human eye (S6) of the second lens E2. The third lens E3 has positive optical power. Its side near the human eye (S8) is concave, and its side near the display (S9) is convex. The fourth lens E4 has positive optical power, and its side S10 near the human eye is convex, while its side S11 near the display screen is convex.

[0119] In this example, an image surface S14 may be provided on the second side of the optical system, and the image surface S14 may, for example, be a display. The optical system also includes a third quarter-wave plate QWP3, which has a near-eye side S12 and a near-display side, with the near-display side attached to the near-eye side S13 of the display. Image light from the display sequentially passes through a fourth lens E4, a third lens E3, a second lens E2, a second quarter-wave plate QWP2, a first lens E1, and a first quarter-wave plate QWP1, and reaches a reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the first quarter-wave plate QWP1 and the first lens E1, and reaches a partial reflective layer BS, where it undergoes a second reflection. The light after the second reflection sequentially passes through the first lens E1, the first quarter-wave plate QWP1, and the reflective polarizing element RP, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system, after two reflections, is finally projected into the user's eye.

[0120] Table 5 shows the basic parameters of the optical system in Example 3, where the units for radius of curvature and thickness / distance are millimeters (mm). The image light from the display passes through each element in the order of number 20 to number 2 and is finally projected into the human eye.

[0121]

[0122]

[0123] Table 5

[0124] In Example 3, the near-display side S4 of the first lens E1, the near-display side S7 of the second lens E2, the near-eye side S8 and the near-display side S9 of the third lens E3, and the near-eye side S10 and the near-display side S11 of the fourth lens E4 are all aspherical. Table 6 shows the higher-order coefficients A4, A6, A8, and A11 that can be used for each aspherical mirror S4, S7-S11 in Example 3. 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 and A 30 .

[0125] Face number A4 A6 A8 A10 A12 A14 A16 S4 5.0634E-01 -1.2190E-03 1.2317E-02 -1.3622E-02 2.7949E-03 -2.1164E-03 1.5758E-03 S7 -2.9245E-01 -7.4404E-02 -5.0916E-02 3.8725E-02 -7.7924E-03 8.2782E-03 -5.7474E-03 S8 4.5214E+00 -8.9246E-01 4.4005E-01 -2.1158E-01 8.5724E-02 -5.4468E-02 1.6747E-02 S9 1.8477E+00 -5.6121E-01 2.0557E-01 -9.4131E-02 5.0505E-02 -3.6924E-02 9.5159E-03 S10 -3.5746E+00 1.0047E+00 -3.8688E-01 2.2027E-01 -1.0819E-01 3.9933E-02 9.5188E-03 S11 7.2500E+00 -1.3014E+00 8.1556E-01 -4.6482E-01 2.5530E-01 -1.8339E-01 1.2867E-01 Face number A18 A20 A22 A24 A26 A28 A30 S4 -8.0946E-04 2.1112E-04 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S7 -3.4718E-03 5.3242E-03 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S8 -3.2346E-03 7.7377E-03 2.9766E-03 -2.6964E-03 -1.6383E-03 -8.9498E-04 -9.7910E-04 S9 2.1668E-02 4.9109E-03 -5.3961E-03 -2.7354E-03 1.6982E-03 -3.7069E-03 1.6443E-03 S10 -2.7178E-03 1.2711E-02 -2.0912E-02 1.1726E-02 -2.7147E-03 6.3528E-04 -1.1476E-04 S11 -7.7853E-02 6.5405E-02 -5.4696E-02 3.8306E-02 -4.1027E-02 2.7785E-02 -6.4506E-03

[0126] Table 6

[0127] Figure 8A The on-axis chromatic aberration curve of the optical system 300 of Embodiment 3 is shown, which represents the deflection of the focal point after light of different wavelengths passes through the optical system 300. Figure 8B The astigmatism curves of the optical system 300 of Embodiment 3 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field of view angles. Figure 8C The distortion curves of the optical system 300 of Embodiment 3 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 8A to 8C It can be seen that the optical system 300 given in Example 3 can achieve good imaging quality.

[0128] Example 4

[0129] The following is for reference Figures 9 to 10C The optical system according to Embodiment 4 of this application is described.

[0130] like Figure 9 As shown, the optical system 400 includes a first element group, a second element group, a third element group, and a fourth element group arranged sequentially along the optical axis from a first side to a second side. The first element group includes a first lens E1, a reflective polarizing element RP, and a first quarter-wave plate QWP1. In other examples, the first element group also includes a partial reflective layer BS (not shown). The second element group includes a second lens E2 and a second quarter-wave plate QWP2. The third element group includes a third lens E3. The fourth element group includes a fourth lens E4. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, fourth lens E4, reflective polarizing element RP, first quarter-wave plate QWP1, and second quarter-wave plate QWP2) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0131] The first lens E1 has positive optical power. Its side near the human eye (S3) is flat, and its side near the display (S4) is convex, with a partial reflective layer (BS) attached. The reflective polarizing element RP has a side near the human eye (S1) and a side near the display. The first quarter-wave plate (QWP1) has a side near the human eye (S2) and a side near the display. The side near the display of the reflective polarizing element RP is attached to the side near the human eye (S2) of the first quarter-wave plate (QWP1), and the side near the display of the first quarter-wave plate (QWP1) is attached to the side near the human eye (S3) of the first lens E1. The second lens E2 has negative optical power. Its side near the human eye (S6) is flat, and its side near the display (S7) is concave. The second quarter-wave plate (QWP2) has a side near the human eye (S5) and a side near the display. Its side near the display is attached to the side near the human eye (S6) of the second lens E2. The third lens E3 has positive optical power. Its side near the human eye (S8) is convex, and its side near the display (S9) is convex. The fourth lens E4 has positive optical power, with its side S10 near the human eye being convex and its side S11 near the display being convex.

[0132] In this example, an image surface S14 may be provided on the second side of the optical system, and the image surface S14 may, for example, be a display. The optical system also includes a third quarter-wave plate QWP3, which has a near-eye side S12 and a near-display side, with the near-display side attached to the near-eye side S13 of the display. Image light from the display sequentially passes through a fourth lens E4, a third lens E3, a second lens E2, a second quarter-wave plate QWP2, a first lens E1, and a first quarter-wave plate QWP1, and reaches a reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the first quarter-wave plate QWP1 and the first lens E1, and reaches a partial reflective layer BS, where it undergoes a second reflection. The light after the second reflection sequentially passes through the first lens E1, the first quarter-wave plate QWP1, and the reflective polarizing element RP, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system, after two reflections, is finally projected into the user's eye.

[0133] Table 7 shows the basic parameters of the optical system in Example 4, where the units for radius of curvature and thickness / distance are millimeters (mm). The image light from the display passes through each element in the order of number 20 to number 2 and is finally projected into the human eye.

[0134]

[0135]

[0136] Table 7

[0137] In Example 4, the near-display side S4 of the first lens E1, the near-display side S7 of the second lens E2, the near-eye side S8 and the near-display side S9 of the third lens E3, and the near-eye side S10 and the near-display side S11 of the fourth lens E4 are all aspherical. Table 8 shows the higher-order coefficients A4, A6, A8, and A11 that can be used for each aspherical mirror S4, S7-S11 in Example 4. 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 and A 30 .

[0138] Face number A4 A6 A8 A10 A12 A14 A16 S4 3.7880E-01 -1.3276E-02 -1.9525E-02 -3.6426E-03 2.2939E-03 -2.1570E-03 -1.7314E-03 S7 4.2963E+00 -2.6099E+00 7.7483E-01 -1.6245E-01 5.9652E-02 -1.7248E-01 2.6885E-02 S8 7.0551E+00 -2.2956E+00 5.5123E-01 -3.0050E-01 1.0096E-01 -3.9728E-02 2.0227E-02 S9 1.6406E+00 3.1010E-01 -1.6278E-01 -5.5014E-02 -2.3162E-01 2.3375E-01 -5.0110E-02 S10 -3.4678E+00 4.7797E-01 -1.8923E-01 1.3875E-02 -1.4342E-01 5.0254E-02 -1.2222E-01 S11 8.4484E+00 -1.0961E+00 7.5517E-01 -7.7316E-01 1.7394E-01 -2.3457E-01 1.7794E-01 Face number A18 A20 A22 A24 A26 A28 A30 S4 5.4551E-04 8.3062E-04 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S7 3.5951E-02 1.9151E-02 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S8 1.3041E-02 4.1169E-03 3.7458E-03 3.2123E-04 6.0696E-06 -2.6117E-03 5.5614E-05 S9 8.0065E-02 -8.9831E-02 5.5650E-02 -7.3454E-02 7.0694E-03 2.9752E-02 2.4033E-02 S10 1.5115E-01 1.4108E-01 1.5007E-01 -1.0094E-01 -1.7390E-02 1.3094E-01 7.1573E-02 S11 -1.2755E-02 2.1377E-01 2.2995E-02 -8.7395E-02 -9.7813E-02 1.0335E-01 2.5634E-02

[0139] Table 8

[0140] Figure 10A The on-axis chromatic aberration curve of the optical system 400 of Embodiment 4 is shown, which represents the deflection of the focal point of light of different wavelengths after passing through the optical system 400. Figure 10B The astigmatism curves of the optical system 400 of Embodiment 4 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field of view angles. Figure 10C The distortion curves of the optical system 400 of Embodiment 4 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 10A to 10C As can be seen, the optical system 400 given in Example 4 can achieve good imaging quality.

[0141] Example 5

[0142] The following is for reference Figures 11 to 12C The optical system according to Embodiment 5 of this application is described.

[0143] like Figure 11As shown, the optical system 500 includes a first element group, a second element group, a third element group, and a fourth element group arranged sequentially along the optical axis from a first side to a second side. The first element group includes a first lens E1, a reflective polarizing element RP, and a first quarter-wave plate QWP1. In other examples, the first element group also includes a partial reflective layer BS (not shown). The second element group includes a second lens E2 and a second quarter-wave plate QWP2. The third element group includes a third lens E3. The fourth element group includes a fourth lens E4. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, fourth lens E4, reflective polarizing element RP, first quarter-wave plate QWP1, and second quarter-wave plate QWP2) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0144] The first lens E1 has positive optical power. Its side near the human eye (S3) is flat, and its side near the display (S4) is convex, with a partial reflective layer (BS) attached. The reflective polarizing element RP has a side near the human eye (S1) and a side near the display. The first quarter-wave plate (QWP1) has a side near the human eye (S2) and a side near the display. The side near the display of the reflective polarizing element RP is attached to the side near the human eye (S2) of the first quarter-wave plate (QWP1), and the side near the display of the first quarter-wave plate (QWP1) is attached to the side near the human eye (S3) of the first lens E1. The second lens E2 has negative optical power. Its side near the human eye (S6) is flat, and its side near the display (S7) is concave. The second quarter-wave plate (QWP2) has a side near the human eye (S5) and a side near the display. Its side near the display is attached to the side near the human eye (S6) of the second lens E2. The third lens E3 has positive optical power. Its side near the human eye (S8) is convex, and its side near the display (S9) is convex. The fourth lens E4 has positive optical power, and its side S10 near the human eye is convex, while its side S11 near the display screen is convex.

[0145] In this example, an image surface S14 may be provided on the second side of the optical system, and the image surface S14 may, for example, be a display. The optical system also includes a third quarter-wave plate QWP3, which has a near-eye side S12 and a near-display side, with the near-display side attached to the near-eye side S13 of the display. Image light from the display sequentially passes through a fourth lens E4, a third lens E3, a second lens E2, a second quarter-wave plate QWP2, a first lens E1, and a first quarter-wave plate QWP1, and reaches a reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the first quarter-wave plate QWP1 and the first lens E1, and reaches a partial reflective layer BS, where it undergoes a second reflection. The light after the second reflection sequentially passes through the first lens E1, the first quarter-wave plate QWP1, and the reflective polarizing element RP, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system, after two reflections, is finally projected into the user's eye.

[0146] Table 9 shows the basic parameters of the optical system in Example 5, where the units for radius of curvature and thickness / distance are millimeters (mm). The image light from the display passes through each element in the order of number 20 to number 2 and is finally projected into the human eye.

[0147]

[0148]

[0149] Table 9

[0150] In Example 5, the near-display side S4 of the first lens E1, the near-display side S7 of the second lens E2, the near-eye side S8 and the near-display side S9 of the third lens E3, and the near-eye side S10 and the near-display side S11 of the fourth lens E4 are all aspherical. Table 10 lists the higher-order coefficients A4, A6, A8, and A11 that can be used for each aspherical mirror S4, S7-S11 in Example 5. 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 and A 30 .

[0151] Face number A4 A6 A8 A10 A12 A14 A16 S4 3.9853E-01 3.6868E-02 -2.3897E-02 -1.4437E-02 5.2343E-03 4.8731E-03 -4.1553E-04 S7 1.7625E+00 -2.4982E+00 8.3879E-01 9.2019E-02 3.8925E-03 -1.2092E-01 1.9140E-02 S8 5.5421E+00 -2.2720E+00 7.2018E-01 -5.5594E-02 9.8185E-02 -9.2562E-02 -1.4617E-02 S9 1.2405E+00 6.0795E-01 -1.8747E-01 -2.3203E-02 -2.5749E-01 1.8481E-01 -2.2571E-02 S10 -2.1849E+00 1.5124E+00 -2.5105E-01 1.2802E-01 -1.0776E-01 1.5629E-01 -1.6604E-01 S11 6.7664E+00 -5.6466E-01 5.3134E-01 -7.6836E-01 2.5238E-01 -6.0800E-02 1.3065E-01 Face number A18 A20 A22 A24 A26 A28 A30 S4 -2.0884E-03 6.0780E-06 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S7 2.5528E-02 -3.7337E-02 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S8 1.2071E-03 -1.0614E-02 4.1488E-02 1.7877E-02 -9.5941E-03 -4.8533E-03 -2.2292E-03 S9 7.3176E-02 -4.1220E-02 9.7475E-02 -1.1009E-01 -6.8528E-03 3.2752E-02 -6.1950E-03 S10 6.2257E-02 3.7105E-02 9.0051E-02 -1.4378E-01 -4.9431E-02 6.4252E-02 7.7923E-03 S11 -1.6456E-01 5.5236E-02 4.7793E-02 2.1940E-02 -7.5710E-02 2.8269E-02 1.1505E-03

[0152] Table 10

[0153] Figure 12A The on-axis chromatic aberration curve of the optical system 500 of Embodiment 5 is shown, which represents the deflection of the focal point of light of different wavelengths after passing through the optical system 500. Figure 12B The astigmatism curves of the optical system 500 of Embodiment 5 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field of view angles. Figure 12C The distortion curves of the optical system 500 of Embodiment 5 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 12A to 12C It can be seen that the optical system 500 given in Example 5 can achieve good imaging quality.

[0154] Example 6

[0155] The following is for reference Figures 13 to 14C The optical system according to Embodiment 6 of this application is described.

[0156] like Figure 13 As shown, the optical system 600 includes a first element group, a second element group, a third element group, and a fourth element group arranged sequentially along the optical axis from a first side to a second side. The first element group includes a first lens E1, a reflective polarizing element RP, and a first quarter-wave plate QWP1. In other examples, the first element group also includes a partial reflective layer BS (not shown). The second element group includes a second lens E2 and a second quarter-wave plate QWP2. The third element group includes a third lens E3. The fourth element group includes a fourth lens E4. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, fourth lens E4, reflective polarizing element RP, first quarter-wave plate QWP1, and second quarter-wave plate QWP2) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0157] The first lens E1 has positive optical power. Its side near the human eye (S3) is flat, and its side near the display (S4) is convex, with a partial reflective layer (BS) attached. The reflective polarizing element RP has a side near the human eye (S1) and a side near the display. The first quarter-wave plate QWP1 has a side near the human eye (S2) and a side near the display. The side near the display of the reflective polarizing element RP is attached to the side near the human eye (S2) of the first quarter-wave plate QWP1, and the side near the display of the first quarter-wave plate QWP1 is attached to the side near the human eye (S3) of the first lens E1. The second lens E2 has negative optical power. Its side near the human eye (S6) is flat, and its side near the display (S7) is concave. The second quarter-wave plate QWP2 has a side near the human eye (S5) and a side near the display, with its side near the display attached to the side near the human eye (S6) of the second lens E2. The third lens E3 has positive optical power. Its side near the human eye (S8) is concave, and its side near the display (S9) is convex. The fourth lens E4 has positive optical power, with its side S10 near the human eye being concave and its side S11 near the display screen being convex.

[0158] In this example, an image surface S14 may be provided on the second side of the optical system, and the image surface S14 may, for example, be a display. The optical system also includes a third quarter-wave plate QWP3, which has a near-eye side S12 and a near-display side, with the near-display side attached to the near-eye side S13 of the display. Image light from the display sequentially passes through a fourth lens E4, a third lens E3, a second lens E2, a second quarter-wave plate QWP2, a first lens E1, and a first quarter-wave plate QWP1, and reaches a reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the first quarter-wave plate QWP1 and the first lens E1, and reaches a partial reflective layer BS, where it undergoes a second reflection. The light after the second reflection sequentially passes through the first lens E1, the first quarter-wave plate QWP1, and the reflective polarizing element RP, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system, after two reflections, is finally projected into the user's eye.

[0159] Table 11 shows the basic parameters of the optical system in Example 6, where the units for radius of curvature and thickness / distance are millimeters (mm). Image light from the display passes through each element in the order of number 20 to number 2 and is finally projected into the human eye.

[0160]

[0161]

[0162] Table 11

[0163] In Example 6, the near-display side S4 of the first lens E1, the near-display side S7 of the second lens E2, the near-eye side S8 and the near-display side S9 of the third lens E3, and the near-eye side S10 and the near-display side S11 of the fourth lens E4 are all aspherical. Table 12 lists the higher-order coefficients A4, A6, A8, and A11 that can be used for each aspherical mirror S4, S7-S11 in Example 6. 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 and A 30 .

[0164] Face number A4 A6 A8 A10 A12 A14 A16 S4 4.0017E-01 2.9386E-02 -2.1659E-02 -1.3859E-02 5.4608E-03 4.2744E-03 -5.5103E-04 S7 1.7575E+00 -2.4378E+00 8.2224E-01 9.0045E-02 -1.2067E-02 -1.2852E-01 1.7684E-02 S8 5.7081E+00 -2.2307E+00 7.0447E-01 -8.7826E-02 8.5295E-02 -9.7380E-02 -7.1900E-03 S9 1.2912E+00 6.4868E-01 -2.0322E-01 -4.0536E-02 -2.5076E-01 1.8791E-01 -2.0268E-02 S10 -1.1249E+00 1.4141E+00 -2.1631E-01 1.3206E-01 -9.7595E-02 1.6532E-01 -1.6258E-01 S11 6.8546E+00 -5.4365E-01 5.3568E-01 -7.6830E-01 2.5110E-01 -6.2553E-02 1.3107E-01 Face number A18 A20 A22 A24 A26 A28 A30 S4 -2.0190E-03 1.7068E-04 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S7 2.4864E-02 -3.3764E-02 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S8 2.7921E-03 1.7930E-03 4.9466E-02 1.6235E-02 -1.5635E-02 -7.7696E-03 -2.1536E-03 S9 6.7769E-02 -4.1022E-02 1.0253E-01 -1.1052E-01 -9.7613E-03 3.0456E-02 -4.1535E-03 S10 5.8768E-02 3.5340E-02 9.5911E-02 -1.4360E-01 -5.1471E-02 6.3893E-02 5.5005E-03 S11 -1.6520E-01 5.5943E-02 4.8244E-02 2.2513E-02 -7.6176E-02 2.8475E-02 1.0187E-03

[0165] Table 12

[0166] Figure 14A The on-axis chromatic aberration curve of the optical system 600 of Embodiment 6 is shown, which represents the deflection of the focal point after light of different wavelengths passes through the optical system 600. Figure 14B The astigmatism curves of the optical system 600 of Embodiment 6 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field of view angles. Figure 14C The distortion curves of the optical system 600 of Embodiment 6 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 14A to 14C As can be seen, the optical system 600 given in Example 6 can achieve good imaging quality.

[0167] Example 7

[0168] The following is for reference Figures 15 to 16C The optical system according to Embodiment 7 of this application is described.

[0169] like Figure 15As shown, the optical system 700 includes a first element group, a second element group, a third element group, and a fourth element group arranged sequentially along the optical axis from a first side to a second side. The first element group includes a first lens E1, a reflective polarizing element RP, and a first quarter-wave plate QWP1. In other examples, the first element group also includes a partial reflective layer BS (not shown). The second element group includes a second lens E2 and a second quarter-wave plate QWP2. The third element group includes a third lens E3. The fourth element group includes a fourth lens E4. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, fourth lens E4, reflective polarizing element RP, first quarter-wave plate QWP1, and second quarter-wave plate QWP2) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0170] The first lens E1 has positive optical power. Its side near the human eye (S3) is flat, and its side near the display (S4) is convex and has a partially reflective layer (BS) attached to it. The reflective polarizing element RP has a side near the human eye (S1) and a side near the display. The first quarter-wave plate QWP1 has a side near the human eye (S2) and a side near the display. The side near the display of the reflective polarizing element RP is attached to the side near the human eye (S2) of the first quarter-wave plate QWP1, and the side near the display of the first quarter-wave plate QWP1 is attached to the side near the human eye (S3) of the first lens E1. The second lens E2 has negative optical power. Its side near the human eye (S5) is concave, and its side near the display (S6) is flat. The second quarter-wave plate QWP2 has a side near the human eye and a side near the display (S7). Its side near the human eye is attached to the side near the display (S6) of the second lens E2. The third lens E3 has positive optical power. Its side near the human eye (S8) is convex, and its side near the display (S9) is convex. The fourth lens E4 has positive optical power, with its side S10 near the human eye being convex and its side S11 near the display being concave.

[0171] In this example, the second side of the optical system may be provided with an image surface S13, which may, for example, be a display, and the display has a side closer to the human eye S12. Image light from the display sequentially passes through a fourth lens E4, a third lens E3, a second quarter-wave plate QWP2, a second lens E2, a first lens E1, and a first quarter-wave plate QWP1, and reaches a reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the first quarter-wave plate QWP1, the first lens E1, and reaches a partial reflective layer BS, where it undergoes a second reflection. The light after the second reflection sequentially passes through the first lens E1, the first quarter-wave plate QWP1, and the reflective polarizing element RP, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system, after two reflections, is finally projected into the user's eye.

[0172] Table 13 shows the basic parameters of the optical system in Example 7, where the units for radius of curvature and thickness / distance are millimeters (mm). The image light from the display passes through each element in the order of number 19 to number 2 and is finally projected into the human eye.

[0173]

[0174] Table 13

[0175] In Example 7, the near-display side S4 of the first lens E1, the near-eye side S5 of the second lens E2, the near-eye side S8 and near-display side S9 of the third lens E3, and the near-eye side S10 and near-display side S11 of the fourth lens E4 are all aspherical. Table 14 lists the higher-order coefficients A4, A6, A8, and A11 that can be used for each aspherical mirror S4, S5, S8-S11 in Example 7. 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 and A 26 .

[0176] Face number A4 A6 A8 A10 A12 A14 S4 9.6484E-01 -5.8118E-02 -3.2365E-04 7.4224E-03 -1.0168E-03 -4.2892E-04 S5 7.4019E+00 -7.8154E-01 -8.4200E-03 -1.5451E-04 -3.3709E-06 -7.8549E-08 S8 3.3033E+00 6.0722E-01 -2.0580E-01 -6.8298E-02 -3.8919E-02 -3.5035E-02 S9 1.0171E+01 -1.1613E+00 -2.5638E-02 -2.0548E-01 8.7486E-02 -6.0957E-03 S10 -9.8505E-01 -1.0561E+00 1.3011E+00 -1.3150E-01 -2.0505E-01 6.1989E-02 S11 -2.6504E+00 8.0567E-01 4.2812E-01 6.0392E-02 -2.0704E-01 -1.9349E-02 Face number A16 A18 A20 A22 A24 A26 S4 -3.0269E-04 -7.8223E-04 -1.3914E-05 0.0000E+00 0.0000E+00 0.0000E+00 S5 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S8 5.4610E-03 4.0733E-03 1.9025E-03 -2.1165E-04 -1.3373E-05 -6.1046E-07 S9 9.4747E-04 5.6004E-03 -2.2649E-03 -2.2624E-05 -1.9802E-07 0.0000E+00 S10 3.1263E-02 -1.5201E-03 -9.2811E-03 -3.3584E-05 1.8998E-06 1.1990E-07 S11 -3.6326E-02 2.9973E-02 3.6279E-03 2.4197E-06 0.0000E+00 0.0000E+00

[0177] Table 14

[0178] Figure 16A The on-axis chromatic aberration curve of the optical system 700 of Embodiment 7 is shown, which represents the deflection of the focal point after light of different wavelengths passes through the optical system 700. Figure 16B The astigmatism curves of the optical system 700 of Embodiment 7 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field of view angles. Figure 16C The distortion curves of the optical system 700 of Embodiment 7 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 16A to 16C As can be seen, the optical system 700 given in Example 7 can achieve good imaging quality.

[0179] Example 8

[0180] The following is for reference Figures 17 to 18C The optical system according to Embodiment 8 of this application is described.

[0181] like Figure 17 As shown, the optical system 800 includes a first element group, a second element group, a third element group, and a fourth element group arranged sequentially along the optical axis from a first side to a second side. The first element group includes a first lens E1, a reflective polarizing element RP, and a first quarter-wave plate QWP1. In other examples, the first element group also includes a partial reflective layer BS (not shown). The second element group includes a second lens E2 and a second quarter-wave plate QWP2. The third element group includes a third lens E3. The fourth element group includes a fourth lens E4. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, fourth lens E4, reflective polarizing element RP, first quarter-wave plate QWP1, and second quarter-wave plate QWP2) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0182] The first lens E1 has positive optical power. Its side near the human eye (S3) is flat, and its side near the display (S4) is convex, with a partial reflective layer (BS) attached. The reflective polarizing element RP has a side near the human eye (S1) and a side near the display. The first quarter-wave plate QWP1 has a side near the human eye (S2) and a side near the display. The side near the display of the reflective polarizing element RP is attached to the side near the human eye (S2) of the first quarter-wave plate QWP1, and the side near the display of the first quarter-wave plate QWP1 is attached to the side near the human eye (S3) of the first lens E1. The second lens E2 has negative optical power. Its side near the human eye (S6) is flat, and its side near the display (S7) is concave. The second quarter-wave plate QWP2 has a side near the human eye (S5) and a side near the display, with its side near the display attached to the side near the human eye (S6) of the second lens E2. The third lens E3 has positive optical power. Its side near the human eye (S8) is concave, and its side near the display (S9) is convex. The fourth lens E4 has positive optical power, and its side S10 near the human eye is convex, while its side S11 near the display screen is convex.

[0183] In this example, an image surface S14 may be provided on the second side of the optical system, and the image surface S14 may, for example, be a display. The optical system also includes a third quarter-wave plate QWP3, which has a near-eye side S12 and a near-display side, with the near-display side attached to the near-eye side S13 of the display. Image light from the display sequentially passes through a fourth lens E4, a third lens E3, a second lens E2, a second quarter-wave plate QWP2, a first lens E1, and a first quarter-wave plate QWP1, and reaches a reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the first quarter-wave plate QWP1 and the first lens E1, and reaches a partial reflective layer BS, where it undergoes a second reflection. The light after the second reflection sequentially passes through the first lens E1, the first quarter-wave plate QWP1, and the reflective polarizing element RP, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system, after two reflections, is finally projected into the user's eye.

[0184] Table 15 shows the basic parameters of the optical system in Example 8, where the units for radius of curvature and thickness / distance are millimeters (mm). Image light from the display passes through each element in the order of number 20 to number 2 and is finally projected into the human eye.

[0185]

[0186] Table 15

[0187] In Example 8, the near-display side S4 of the first lens E1, the near-display side S7 of the second lens E2, the near-eye side S8 and the near-display side S9 of the third lens E3, and the near-eye side S10 and the near-display side S11 of the fourth lens E4 are all aspherical. Table 16 lists the higher-order coefficients A4, A6, A8, and A11 that can be used for each aspherical mirror S4, S7-S11 in Example 8. 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 and A 30 .

[0188] Face number A4 A6 A8 A10 A12 A14 A16 S4 5.0634E-01 -1.2190E-03 1.2317E-02 -1.3622E-02 2.7949E-03 -2.1164E-03 1.5758E-03 S7 -2.9245E-01 -7.4404E-02 -5.0916E-02 3.8725E-02 -7.7924E-03 8.2782E-03 -5.7474E-03 S8 4.5214E+00 -8.9246E-01 4.4005E-01 -2.1158E-01 8.5724E-02 -5.4468E-02 1.6747E-02 S9 1.8477E+00 -5.6121E-01 2.0557E-01 -9.4131E-02 5.0505E-02 -3.6924E-02 9.5159E-03 S10 -3.5746E+00 1.0047E+00 -3.8688E-01 2.2027E-01 -1.0819E-01 3.9933E-02 9.5188E-03 S11 7.2500E+00 -1.3014E+00 8.1556E-01 -4.6482E-01 2.5530E-01 -1.8339E-01 1.2867E-01 Face number A18 A20 A22 A24 A26 A28 A30 S4 -8.0946E-04 2.1112E-04 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S7 -3.4718E-03 5.3242E-03 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S8 -3.2346E-03 7.7377E-03 2.9766E-03 -2.6964E-03 -1.6383E-03 -8.9498E-04 -9.7910E-04 S9 2.1668E-02 4.9109E-03 -5.3961E-03 -2.7354E-03 1.6982E-03 -3.7069E-03 1.6443E-03 S10 -2.7178E-03 1.2711E-02 -2.0912E-02 1.1726E-02 -2.7147E-03 6.3528E-04 -1.1476E-04 S11 -7.7853E-02 6.5405E-02 -5.4696E-02 3.8306E-02 -4.1027E-02 2.7785E-02 -6.4506E-03

[0189] Table 16

[0190] Figure 18AThe on-axis chromatic aberration curve of the optical system 800 of Embodiment 8 is shown, which represents the deflection of the focal point after light of different wavelengths passes through the optical system 800. Figure 18B The astigmatism curves of the optical system 800 of Embodiment 8 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field of view angles. Figure 18C The distortion curves of the optical system 800 of Embodiment 8 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 18A to 18C As can be seen, the optical system 800 given in Example 8 can achieve good imaging quality.

[0191] Table 17 gives the values ​​of the basic parameters for each of the embodiments in Examples 1 to 8.

[0192] Conditional / Example 1 2 3 4 5 6 7 8 f(mm) 14.06 13.94 13.95 14.27 13.96 14.06 20.80 13.95 F1 (mm) 15.44 15.26 15.58 16.06 15.25 15.18 15.17 15.58 F2 (mm) -242.13 10000.00 -2235.80 -236.97 -240.29 -240.16 -112.58 -2235.80 F3 (mm) 89.03 57.17 192.88 86.27 54.18 44.30 33.96 192.88 F4 (mm) 22.23 22.61 20.61 17.15 21.38 24.52 118.59 20.61 FOV (°) 110.0 110.0 100.0 86.0 110.0 110.0 110.0 110.0 EPD (mm) 5.00 5.00 4.00 5.00 5.00 5.00 5.00 5.00

[0193] Table 17

[0194] In summary, Table 18 shows the values ​​of the conditional expressions for each of the embodiments in Examples 1 to 8.

[0195] Conditional / Example 1 2 3 4 5 6 7 8 TD / f 1.18 1.19 1.17 1.26 1.19 1.18 0.86 1.17 CT3 / ((N2+N3)×T23) 9.17 11.76 9.29 11.31 11.62 11.66 11.40 9.29 (T23+CT2+CT3)×(V2+V3) / |(F2+F3)| 3.62 0.06 0.26 4.25 3.42 3.30 8.77 0.26 R2 / ((CT1+T12+CT2)×(N1+N2)) -2.22 -2.21 -2.15 -2.35 -2.21 -2.20 -1.72 -2.15 (R5-R6) / (R5+R6) 0.93 0.72 0.64 1.03 1.00 0.93 1.02 0.64 F4 / R7-F4 / R8 1.89 1.47 1.90 1.50 1.48 1.47 1.96 1.90 (R6-R8) / (CT3+T34+CT4) -3.43 -1.03 -7.88 -3.04 -1.36 -0.71 -14.17 -7.88 (V3×CT3+V4×CT4) / (F3+F4) 4.28 5.22 2.09 4.25 5.45 6.04 2.05 2.09 TD / (tan(FOV / 2)×f) 0.83 0.83 0.98 1.35 0.83 0.83 0.60 0.82 |R5+R6| / F3 14.30 3.19 2.39 33.84 832.08 15.89 78.60 2.39 (F3×T34 / N3+F4×T34 / N4) / f 0.82 0.58 1.59 0.75 0.55 0.50 1.31 1.59 F1 / f 1.10 1.09 1.12 1.13 1.09 1.08 0.73 1.12 F3 / f 6.33 4.10 13.82 6.05 3.88 3.15 1.63 13.82 F4 / f 1.58 1.62 1.48 1.20 1.53 1.74 5.70 1.48 (CTR+CTQ1+CT1)×(VR+VQ1+V1) / F1 64.64 64.93 67.02 61.10 64.87 65.27 46.57 67.02 (NR+NQ1)×R2 / ((N1+N2)×F1) -3.09 -3.09 -3.08 -3.10 -3.09 -3.09 -3.32 -3.08 (DT31+DT42) / |(R6+R8)| 0.47 0.68 0.29 0.40 0.63 0.73 0.48 0.30 R2 / (DT12+DT21) -1.37 -1.36 -1.46 -1.80 -1.36 -1.35 -1.35 -1.29

[0196] Table 18

[0197] This application also provides an optical device, which can be a standalone projection device such as a projector, or a projection module integrated into a mobile electronic device such as a virtual reality device. The optical device is equipped with the optical system described above.

[0198] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. Optical system, characterized in that sequentially include, along the optical axis from the first side to the second side: a first element group including a first lens having positive refractive power, a reflective polarizing element, and a first quarter-wave plate, the reflective polarizing element being located on a first side of the first quarter-wave plate, the first quarter-wave plate being attached to a first side of the first lens; a second side of the first lens being provided with a partial reflection layer; the first side of the first lens being a plane, and the second side being a convex surface; a second element group including a second lens and a second quarter-wave plate, the second quarter-wave plate being located on a first side or a second side of the second lens; a third element group including a third lens having positive refractive power; a second side of the third lens being a convex surface; a fourth element group including a fourth lens having positive refractive power; wherein the number of lenses having refractive power in the optical system is four; the first side is an eye side, and the second side is a display side; and an on-axis distance TD from the first side of the first element group to the second side of the fourth element group satisfies: 0.86≤TD / f<1.3, where f is a total effective focal length of the optical system; a radius of curvature R6 of the second side of the third lens, a radius of curvature R8 of the second side of the fourth lens, a central thickness CT3 of the third lens on the optical axis, a central thickness CT4 of the fourth lens on the optical axis, and an air gap T34 of the third element group and the fourth element group on the optical axis satisfy: -14.17≤(R6-R8) / (CT3+T34+CT4)≤-0.

71.

2. The optical system of claim 1, wherein a central thickness CT3 of the third lens on the optical axis, a refractive index N2 of the second lens, a refractive index N3 of the third lens, and an air gap T23 of the second element group and the third element group on the optical axis satisfy: 9.17≤CT3 / ((N2+N3)×T23)≤11.

76.

3. The optical system of claim 1, wherein a central thickness CT2 of the second lens on the optical axis, a central thickness CT3 of the third lens on the optical axis, an air gap T23 of the second element group and the third element group on the optical axis, a dispersion coefficient V2 of the second lens, a dispersion coefficient V3 of the third lens, an effective focal length F2 of the second element group, and an effective focal length F3 of the third element group satisfy: 0.06≤(T23+CT2+CT3)×(V2+V3) / |(F2+F3)|≤8.

77.

4. The optical system of claim 1, wherein a maximum field of view FOV of the optical system satisfies: 86.00°≤FOV≤110.00°.

5. The optical system of claim 1, wherein a radius of curvature R2 of the second side of the first lens, a central thickness CT1 of the first lens on the optical axis, a central thickness CT2 of the second lens on the optical axis, an air gap T12 of the first element group and the second element group on the optical axis, a refractive index N1 of the first lens, and a refractive index N2 of the second lens satisfy: -2.35≤R2 / ((CT1+T12+CT2)×(N1+N2))≤-1.

72.

6. The optical system of claim 1, wherein A radius of curvature R5 of a first side surface of the third lens and a radius of curvature R6 of a second side surface of the third lens satisfy: 0.64 ≤ (R5-R6) / (R5+R6) ≤ 1.

03.

7. The optical system of claim 1, wherein A radius of curvature R7 of a first side surface of the fourth lens, a radius of curvature R8 of a second side surface of the fourth lens, and an effective focal length F4 of the fourth element group satisfy: 1.47 ≤ F4 / R7-F4 / R8 < 2.

0.

8. The optical system of claim 1, wherein, A dispersion coefficient V3 of the third lens, a dispersion coefficient V4 of the fourth lens, a central thickness CT3 of the third lens on the optical axis, a central thickness CT4 of the fourth lens on the optical axis, an effective focal length F3 of the third element group, and an effective focal length F4 of the fourth element group satisfy: 2.05 ≤ (V3×CT3+V4×CT4) / (F3+F4) ≤ 6.

04.

9. The optical system according to claim 1 or 4, characterized by An on-axis distance TD from the first side surface of the first element group to the second side surface of the fourth element group, a maximum field angle FOV of the optical system, and a total effective focal length f of the optical system satisfy: 0.60 ≤ TD / (tan(FOV / 2)×f) ≤ 1.

35.

10. The optical system according to claim 1 or 6, characterized by A radius of curvature R5 of a first side surface of the third lens, a radius of curvature R6 of a second side surface of the third lens, and an effective focal length F3 of the third element group satisfy: 2.39 ≤ |R5+R6| / F3 ≤ 832.

08.

11. The optical system according to claim 1 or 8, characterized by An effective focal length F3 of the third element group, an effective focal length F4 of the fourth lens group, an air separation T34 of the third element group and the fourth element group on the optical axis, a refractive index N3 of the third lens, a refractive index N4 of the fourth lens, and a total effective focal length f of the optical system satisfy: 0.50 mm ≤ (F3×T34 / N3+F4×T34 / N4) / f < 1.6 mm.

12. The optical system of any one of claims 1-8, wherein, An effective focal length F1 of the first element group and a total effective focal length f of the optical system satisfy: 0.73 ≤ F1 / f ≤ 1.

13.

13. The optical system of any one of claims 1-8, wherein, An effective focal length F3 of the third element group and a total effective focal length f of the optical system satisfy: 1.63 ≤ F3 / f ≤ 13.

82.

14. The optical system of any one of claims 1-8, wherein, An effective focal length F4 of the fourth element group and a total effective focal length f of the optical system satisfy: 1.20 ≤ F4 / f ≤ 5.

70.

15. The optical system of any one of claims 1-8, wherein, A central thickness CTR of the reflective polarizing element on the optical axis, a central thickness CTQ1 of the first quarter-wave plate on the optical axis, a central thickness CT1 of the first lens on the optical axis, a dispersion coefficient VR of the reflective polarizing element, a dispersion coefficient VQ1 of the first quarter-wave plate, a dispersion coefficient V1 of the first lens, and an effective focal length F1 of the first element group satisfy: 46.57 ≤ (CTR+CTQ1+CT1)×(VR+VQ1+V1) / F1 ≤ 67.

02.

16. The optical system of any one of claims 1-8, wherein, The refractive index NR of the reflective polarizing element, the refractive index NQ1 of the first quarter-wave plate, the refractive index N1 of the first lens, the refractive index N2 of the second lens, the curvature radius R2 of the second side of the first lens, and the effective focal length F1 of the first element group satisfy: -3.32 ≤ (NR + NQ1) x R2 / ((N1 + N2) x F1) ≤ -3.

08.

17. The optical system of any one of claims 1-8, wherein, The maximum effective half aperture radius DT31 of the first side of the third lens, the maximum effective half aperture radius DT42 of the second side of the fourth lens, the curvature radius R6 of the second side of the third lens, and the curvature radius R8 of the second side of the fourth lens satisfy: 0.29 ≤ (DT31 + DT42) / |(R6 + R8)| ≤ 0.

73.

18. The optical system of any one of claims 1-8, wherein, The curvature radius R2 of the second side of the first lens, the maximum effective half aperture radius DT12 of the second side of the first lens, and the maximum effective half aperture radius DT21 of the first side of the second lens satisfy: -1.80 ≤ R2 / (DT12 + DT21) ≤ -1.

29.

19. The optical system of any one of claims 1-8, wherein, The first side or the second side of the second lens is configured as a plane.

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