Optical system and head-mounted device

Abstract

The application discloses an optical system and a head-mounted device. The optical system comprises a first lens, a second lens and a third lens along an optical axis from a projection side to an image source side in sequence. The first lens has positive refractive power, and its image source side surface is convex near the optical axis. The first lens is movable along the optical axis. The second lens has refractive power, and its projection side surface is concave near the optical axis. The third lens has positive refractive power, and its projection side surface and image source side surface are both convex near the optical axis. Between the projection side surface of the first lens and the image source side surface of the optical system, a polarization reflection structure, a first phase retarder and a light splitting element are sequentially arranged on the surfaces from the projection side to the image source side along the optical axis. The first phase retarder and the light splitting element are respectively located on the projection side and the image source side of the first lens. The optical system and the head-mounted device can adapt to different degrees of myopia of different users on the basis of realizing miniaturization design.

Description

Technical Field

[0001] This application relates to the field of optical imaging technology, and more particularly to an optical system and a head-mounted device. Background Technology

[0002] With technological advancements and the needs of socio-economic development, virtual reality technology has developed rapidly, leading to the emergence of head-mounted devices (such as VR glasses) utilizing this technology. However, the optical systems in conventional head-mounted devices are typically quite long due to magnification limitations, hindering miniaturization and making them unsuitable for compact head-mounted devices. Furthermore, because users have varying degrees of myopia, most head-mounted devices lack optical systems that adjust to different vision levels, impacting the user experience. Summary of the Invention

[0003] This application discloses an optical system and a head-mounted device that can adapt to different users' myopia levels while achieving a miniaturized design, effectively improving the user experience.

[0004] To achieve the above objectives, in a first aspect, this application discloses an optical system comprising three lenses with refractive power, wherein the optical system comprises, sequentially along the optical axis from the projection side to the image source side:

[0005] The first lens has positive refractive power, and the image source side surface of the first lens is convex near the optical axis. The first lens is movable along the optical axis.

[0006] The second lens has refractive power, and the projection side surface of the second lens is concave near the optical axis;

[0007] The third lens has positive refractive power, and both the projection side surface and the image source side surface of the third lens are convex near the optical axis.

[0008] Between the projection side surface of the first lens and the image source side surface of the optical system, along the optical axis from the projection side to the image source side, a polarization reflection structure, a first phase retarder and a beam splitter are sequentially provided on the surface, with the first phase retarder and the beam splitter located on the projection side and the image source side of the first lens, respectively.

[0009] By incorporating three refractive lenses, and combining them with a polarization reflection structure, a first phase retardation plate, and a beam splitter, the optical system can achieve polarization refraction, transmission, and reflection of light within a limited number of lenses. This allows for light path deflection and folding with a limited number of lenses, effectively reducing the overall size of the optical system without increasing the number of lenses, thus facilitating a slimmer and more compact design. Furthermore, by including a beam splitter on the image source side of the first lens, the optical system can better focus light rays across a wide viewing angle onto the beam splitter for transmission or reflection. This is beneficial for matching a large image source surface, thereby expanding the field of view.

[0010] In addition, by setting a first lens with positive refractive power, and the projection side surface of the first lens being convex near the optical axis, a second lens with refractive power, and the projection side surface of the second lens being concave near the optical axis, and a third lens with positive refractive power, and the projection side surface and image source side surface of the third lens being convex near the optical axis, it is possible to facilitate the entry of light into the optical system, thereby better focusing light within a wide field of view, which is beneficial for matching a large image source surface and thus expanding the field of view.

[0011] Furthermore, the optical system of this application also allows the first lens to be movable along the optical axis of the optical system, enabling the optical system to adjust the movement of the third lens along the optical axis according to the degree of myopia of different users, thereby achieving focusing and adapting to the degree of myopia of different users, thus improving the user experience.

[0012] As an optional implementation, the refractive power adjustment range of the optical system is 0D-8D. This allows the optical system to adapt to the myopia focal length range of 0-500 degrees, catering to individuals with myopia of 0-500 degrees. Furthermore, during the focusing process of the first lens movement, the optical system can maintain image quality within a 120° range for both central and peripheral viewing angles, ensuring the image sharpness of the optical system. Exceeding the relational range will result in excessive or insufficient movement of the first lens along the optical axis. On the one hand, this will cause interference between optical elements or ineffective utilization of the space between lenses, hindering the miniaturization and thinning of the optical system; on the other hand, it will prevent effective control of the focal length adjustment of the optical system, affecting the image sharpness and reducing image quality.

[0013] As an optional implementation, the optical system further includes a first protective glass located between the projection side of the optical system and the projection side surface of the first lens, and the optical system satisfies the following relationship:

[0014] 1.2 < TTL / ft2 < 1.7; where TTL is the distance on the optical axis from the projection side surface of the first protective glass to the image source surface of the optical system, and ft2 is the focal length of the optical system in telephoto mode. This allows for both miniaturization of the optical system and efficient configuration of its focal length.

[0015] As an optional implementation, the optical system satisfies the following relationship: 0.65 < IH / ft2 < 1.1, and / or, 1.1 < D11 / IH < 1.8;

[0016] Wherein, IH is the image height corresponding to half of the maximum field of view of the optical system, ft2 is the focal length of the optical system in telephoto mode, and D11 is the maximum effective half-aperture of the projection side surface of the first lens.

[0017] When the optical system meets the requirement of 0.65 < IH / ft < 1.1, it can help provide a wide field of view and enhance the miniaturization design of the optical system and the head-mounted device to which it is applied.

[0018] When the optical system satisfies 1.1 < D11 / IH < 1.8, the aperture of the optical system head can be adapted to a photosensitive chip with a large image area, which is beneficial to improving the imaging resolution and enabling the optical system to have a high pixel effect.

[0019] As an optional implementation, the optical system satisfies the following relationships: <f1 / ft2<11, and / or, 5<|f2| / ft2, and / or, 1.6<f3 / ft2<3.2, and / or, 0.9<ft2 / ft1<1.2;

[0020] Wherein, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, ft2 is the focal length of the optical system in telephoto mode, and ft1 is the focal length of the optical system in short focal length mode.

[0021] When the optical system satisfies the above relationship, the ratio of the focal length of each lens to the focal length of the optical system can be reasonably controlled, so that the refractive power of each lens in the optical system is properly distributed, which helps to reduce the generation of aberrations and avoids problems in image correction of the optical system caused by excessive changes in the refractive power of a certain lens.

[0022] As an optional implementation, the projection-side surface of the first lens is a flat curved surface, and the radius of curvature R1 of the projection-side surface of the first lens at the optical axis satisfies: |R1|>80mm. That is, the projection-side surface of the first lens is relatively flat, which facilitates the mounting of the first phase retardation film and reduces the difficulty of mounting.

[0023] As an optional implementation, the optical system satisfies the following relationships: |R1| / R2 < -2, and / or, |R4| / R3 < -1, and / or, 4 < R5 / R6;

[0024] Wherein, R1 is the radius of curvature of the projection-side surface of the first lens at the optical axis, R2 is the radius of curvature of the image-source-side surface of the first lens at the optical axis, R4 is the radius of curvature of the image-source-side surface of the second lens at the optical axis, R3 is the radius of curvature of the projection-side surface of the second lens at the optical axis, R5 is the radius of curvature of the projection-side surface of the third lens at the optical axis, and R6 is the radius of curvature of the image-source-side surface of the third lens at the optical axis.

[0025] When the optical system satisfies the above relationship, it can effectively control the ratio of the radius of curvature of the projection side surface of each lens to the radius of curvature of the image source side surface of each lens at the optical axis, thereby effectively controlling the surface shape of the projection side surface and the image source side surface of each lens, which helps to reduce the reflection of light between adjacent lenses and thus reduce the ghost image intensity of the optical system.

[0026] As an optional implementation, the optical system satisfies the following relationship: 1.3 < CT3 / CT1 < 2.5, and / or, 1.5 < CT3 / CT2 < 3, and / or, 0.8 < CT1 / CT2 < 2, and / or, 15 < CT2 / AT23, and / or, 6 < (CT1 + CT2 + CT3) / (AT12 - AT23) < 10;

[0027] Wherein, CT2 is the thickness of the second lens on the optical axis, CT1 is the thickness of the first lens on the optical axis, CT3 is the thickness of the third lens on the optical axis, AT23 is the distance on the optical axis from the image source side surface of the second lens to the projection side surface of the third lens, and AT12 is the distance on the optical axis from the image source side surface of the first lens to the projection side surface of the second lens.

[0028] When the optical system satisfies the above relationship 1.3 < CT3 / CT1 < 2.5, and / or 1.5 < CT3 / CT2 < 3, and / or 0.8 < CT1 / CT2 < 2, the center thickness of each lens can be reasonably controlled, which facilitates the control of the optical power of each lens, enables the aberrations of each lens to compensate for each other, reduces the aberrations of the optical system, and helps to improve the imaging quality of the optical system.

[0029] When the optical system satisfies the relationship 15 < CT2 / AT23, the thickness of the second lens can be reasonably controlled, making the thickness of the second lens and the spacing between the second and third lenses reasonable, which facilitates the assembly of the second and third lenses and avoids assembly interference.

[0030] Since the first lens is movable along the optical axis, when the optical system satisfies the relationship 6 < (CT1 + CT2 + CT3) / (AT12 - AT23) < 10, the amount of movement of the first lens along the optical axis can be effectively controlled. This avoids the distance between the first and second lenses being too large or too small, ensuring sufficient transmission space for light and facilitating light convergence. Furthermore, the thickness of each lens and the spacing between lenses can be reasonably controlled, avoiding assembly interference and reducing assembly difficulty.

[0031] As an optional implementation, the optical system satisfies the following relationship: 90° < FOV < 115°; where FOV is the maximum field of view of the optical system.

[0032] When an optical system satisfies the above relationship, it can achieve wide-angle imaging.

[0033] Secondly, this application also discloses a head-mounted device, which includes a housing, a display, and an optical system as described in the first aspect above, wherein the display and the optical system are disposed in the housing, and the display is located on the image source side of the optical system.

[0034] Compared with the prior art, the beneficial effects of this application are as follows:

[0035] By incorporating three refractive lenses, and combining them with a polarization reflection structure, a first phase retardation plate, and a beam splitter, the optical system can achieve polarization refraction, transmission, and reflection of light within a limited number of lenses. This allows for light path deflection and folding with a limited number of lenses, effectively reducing the overall size of the optical system without increasing the number of lenses, thus facilitating a slimmer and more compact design. Furthermore, by including a beam splitter on the image source side of the first lens, the optical system can better focus light rays across a wide viewing angle onto the beam splitter for transmission or reflection. This is beneficial for matching a large image source surface, thereby expanding the field of view.

[0036] In addition, by setting a first lens with positive refractive power, and the projection side surface of the first lens being convex near the optical axis, a second lens with refractive power, and the projection side surface of the second lens being concave near the optical axis, and a third lens with positive refractive power, and the projection side surface and image source side surface of the third lens being convex near the optical axis, it is possible to facilitate the entry of light into the optical system, thereby better focusing light within a wide field of view, which is beneficial for matching a large image source surface and thus expanding the field of view.

[0037] Furthermore, the optical system of this application also allows the first lens to be movable along the optical axis of the optical system, enabling the optical system to adjust the movement of the third lens along the optical axis according to the degree of myopia of different users, thereby achieving focusing and adapting to the degree of myopia of different users, thus improving the user experience. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the optical system disclosed in Embodiment 1 of this application;

[0040] Figure 2 This is a graph showing the astigmatism and distortion of the optical system disclosed in Embodiment 1 of this application;

[0041] Figure 3 This is a spherical aberration curve of the optical system disclosed in Embodiment 1 of this application;

[0042] Figure 4 This is a schematic diagram of the optical system disclosed in Embodiment 2 of this application;

[0043] Figure 5 This is a graph showing the astigmatism and distortion of the optical system disclosed in Embodiment 2 of this application;

[0044] Figure 6 This is a spherical aberration curve of the optical system disclosed in Embodiment 2 of this application;

[0045] Figure 7 This is a schematic diagram of the optical system disclosed in Embodiment 3 of this application;

[0046] Figure 8 This is a graph showing the astigmatism and distortion of the optical system disclosed in Embodiment 3 of this application;

[0047] Figure 9 This is a spherical aberration curve of the optical system disclosed in Embodiment 3 of this application;

[0048] Figure 10 This is a schematic diagram of the optical system disclosed in Embodiment 4 of this application;

[0049] Figure 11 This is a graph showing the astigmatism and distortion of the optical system disclosed in Embodiment 4 of this application;

[0050] Figure 12This is a spherical aberration curve of the optical system disclosed in Embodiment 4 of this application;

[0051] Figure 13 This is a schematic diagram of the optical system disclosed in Embodiment 5 of this application;

[0052] Figure 14 This is a graph showing the astigmatism and distortion of the optical system disclosed in Embodiment 5 of this application;

[0053] Figure 15 This is a spherical aberration curve of the optical system disclosed in Embodiment 5 of this application;

[0054] Figure 16 This is a schematic diagram of the structure of the head-mounted device disclosed in this application. Detailed Implementation

[0055] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0056] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0057] Please see Figure 1 , Figure 1 This is a schematic diagram of the optical system. Figure 1 (a) in the diagram is a schematic of the optical system in a short focal length state. Figure 1 (b) in the diagram is a schematic diagram of the optical system in the central focal state. Figure 1 (c) is a schematic diagram of the optical system in telephoto mode. According to a first aspect of this application, an optical system 100 is disclosed. This optical system 100 comprises three lenses with refractive power, arranged along the optical axis from the projection side to the image source side. The optical system 100 sequentially includes a first lens L1, a second lens L2, and a third lens L3. The first lens L1 has positive refractive power, the second lens L2 has either positive or negative refractive power, and the third lens L3 has positive refractive power. The first lens L1 is movable along the optical axis, thereby enabling the focusing function of the optical system to adapt to users with different degrees of myopia.

[0058] It is understood that the optical system 100 can be applied to a head-mounted device. Therefore, the projection side of the optical system 100 refers to the side facing the user's eyes, while the image source side of the optical system 100 is the side facing, for example, the display of the head-mounted device.

[0059] Understandably, from Figure 1 As can be seen, when the optical system switches from a short-focus to a long-focus state, it does so by moving the first lens L1 away from the second lens L2 along the optical axis, thus increasing the distance between the first lens L1 and the second lens L2 on the optical axis. Specifically, in the short-focus state, the first lens L1 is closest to the second lens L2; ​​in the medium-focus state, the distance between the first lens L1 and the second lens L2 increases; and in the long-focus state, the distance between the first lens L1 and the second lens L2 is at its maximum. Alternatively, in other embodiments, the optical system 100 can switch from a short-focus to a long-focus state by decreasing the distance between the first lens L1 and the second lens L2 on the optical axis. That is, in the short-focus state, the first lens L1 is furthest from the second lens L2; ​​in the medium-focus state, the distance between the first lens L1 and the second lens L2 decreases; and in the long-focus state, the distance between the first lens L1 and the second lens L2 is at its minimum.

[0060] Optionally, a polarization reflection structure (not shown), a first phase retarder (not shown), and a beam splitter (not shown) are sequentially provided on the surface from the projection side to the image source side of the optical system 100 between the projection side surface of the first lens L1 and the image source side surface IMG. The first phase retarder and the beam splitter are located on the projection side and the image source side of the first lens L1, respectively.

[0061] By setting the optical system 100 to also include a beam splitter, and the beam splitter is located on the image source side of the first lens L1, it is possible to better focus light rays within a wide field of view onto the beam splitter for transmission or reflection, which is beneficial for matching a large image source surface and thus expanding the field of view.

[0062] It is understood that as long as the polarization reflection structure, the first phase retarder and the beam splitter are sequentially arranged between the projection side surface S1 of the first lens L1 and the image source side surface of the optical system 100, and the first phase retarder and the beam splitter are located on the projection side and the image source side of the first lens L1 respectively, this embodiment does not specifically limit the specific arrangement position.

[0063] For example, when the polarization reflection structure is disposed between the projection side and the projection side surface S1 of the first lens L1, the first phase delay sheet can be disposed between the polarization reflection structure and the projection side surface S1 of the first lens L1, and the beam splitting element can be disposed on the image source side surface S2 of the first lens L1.

[0064] Optionally, the polarization reflection structure may include a polarization reflection film and a first polarizer, which are sequentially stacked along the optical axis from the projection side to the image source side. For example, the polarization reflection film can be attached to the projection side surface S1 of the first lens L1, and then the first polarizer can be attached to the polarization reflection film. Alternatively, in other embodiments, a first protective glass P1 (i.e., flat glass) can be added between the projection side and the projection side surface S1 of the first lens L1, thereby sequentially stacking the polarization reflection film and the first polarizer on the first protective glass P1. Of course, in other embodiments, the polarization reflection structure may only include the polarization reflection film, or it may only include the first polarizer.

[0065] Optionally, the first phase retarder can be attached to the polarization reflection structure, or it can be directly attached to the projection side surface of the first lens. It is understood that the first phase retarder can be, for example, a quarter-wave plate or a half-wave plate, to rotate the polarized light to obtain the desired polarization direction, thereby achieving effective control of the optical path to meet design requirements.

[0066] Optionally, a lens may be provided between the first phase retardation plate and the beam splitter on the surface along the optical axis from the projection side to the image source side. That is, the beam splitter may be disposed on the image source side surface S2 of the first lens L1, or a flat glass plate may be added between the second lens L2 and the first lens L1, and then the beam splitter may be disposed on the flat glass plate, as long as the beam splitter is located between the image source side surface S2 of the first lens L1 and the projection side surface S3 of the second lens L2.

[0067] Optionally, the optical system 100 further includes a second protective glass P2, which is disposed between the image source side surface S6 of the third lens L3 and the image source surface of the optical system 100.

[0068] In addition, the optical system may also include a second phase retarder and a polarizer. The second phase retarder may be attached to the second protective glass P2 on the image source of the optical system, or it may be disposed between the image source side surface S2 of the first lens L1 and the projection side surface S3 of the second lens L2. For example, it may be directly attached to the projection side surface of the second lens L2, or it may be directly attached to the image source side surface of the first lens L1.

[0069] The optical path of the optical system 100 of this application is briefly described below.

[0070] like Figure 1As shown, when light forms an image along the optical path, the light emitted from the image source surface IMG (generally the display screen of a head-mounted device) is first circularly polarized light. For example, the display screen of a head-mounted device typically includes a linear polarizer and a phase retardation plate, so the light emitted from the image source surface IMG of the display screen is first circularly polarized light. Further, from the projection side to the image source side, a polarization reflection structure, a first phase retardation plate, and a beam splitter are sequentially provided. For example, the polarization reflection structure is disposed on the projection side and the projection side surface S1 of the first lens L1; the first phase retardation plate is disposed on the projection side surface S1 of the first lens L1, preferably a quarter-wave plate; and the beam splitter is disposed on the projection side surface S3 of the second lens L2, preferably a semi-reflective and semi-transparent film. Thus, the first circularly polarized light sequentially passes through the third lens L3, the second lens L2, the beam splitter, and the image source surface of the first lens L1. The light is transmitted through the source-side surface S2 and reflected by the projection-side surface S1 of the first lens L1, its polarization reflection structure, and the first phase retardation plate, causing the first circularly polarized light to become the first linearly polarized light. The first linearly polarized light passes through the second lens L2 and is reflected by the beam splitter on the projection-side surface S3 of the second lens L2. It then passes through the first phase retardation plate on the first lens L1 again, and under the action of the first phase retardation plate, the first linearly polarized light becomes the second circularly polarized light. The deflection direction of the second circularly polarized light is opposite to that of the first circularly polarized light. Thus, the second circularly polarized light is reflected again by the beam splitter on the projection-side surface S3 of the second lens L2 and passes through the first phase retardation plate on the first lens L1, changing from the second circularly polarized light to the second linearly polarized light. After passing through the polarization reflection structure and the first protective glass P1, the second linearly polarized light is transmitted to the projection surface, thus completing the image formation on the human eye by the virtual reality device.

[0071] In some embodiments, the projection-side surface S1 of the first lens L1 may be concave or convex near the optical axis, the image-source-side surface S2 of the first lens L1 may be convex near the optical axis, the projection-side surface S3 of the second lens L2 may be concave near the optical axis, and the image-source-side surface S4 of the second lens L2 may be convex or concave near the optical axis. The projection-side surface S5 of the third lens L3 may be convex near the optical axis, and the image-source-side surface S6 of the third lens L3 may be convex near the optical axis. The projection-side surfaces of all the above lenses face the human eye, while the image-source-side surfaces of all the above lenses face the image source.

[0072] Optionally, the first lens L1, the second lens L2, and the third lens L3 can all be plastic lenses, thereby achieving the thinness and lightness of the optical system 100 while facilitating the machining of the complex surface of the lenses. Alternatively, the first lens L1, the second lens L2, and the third lens L3 can also be glass lenses, so that while the optical system 100 has good optical effects, the temperature sensitivity of the optical system 100 can also be reduced. Of course, some lenses can be set as glass lenses and some lenses can be set as plastic lenses, which can be adjusted according to the actual situation, and this embodiment does not make specific limitations in this regard.

[0073] Optionally, as can be seen from the foregoing, the first lens L1 is movable along the optical axis direction, and the diopter adjustment range of the optical system 100 is 0D - 8D. In this way, the optical system 100 can be adapted to the myopia focal length range of 0 - 500 degrees and is suitable for myopic people with a degree of 0 - 500. Moreover, during the focusing process of the first lens L1, the optical system 100 can maintain the quality of the image within a central and peripheral viewing angle of 120°, ensuring the imaging clarity of the optical system 100. Beyond the relational range, it will cause the movement amount of the first lens L1 in the optical axis direction to be too large or too small. On the one hand, it will cause interference between optical elements or the ineffective use of the arrangement space between the lenses, which is not conducive to the thinness, lightness, and miniaturization of the optical system 100. On the other hand, it cannot effectively control the focal length adjustment of the optical system 100, affecting the imaging clarity of the optical system 100 and reducing the image quality.

[0074] In some embodiments, the field of view FOV of the optical system 100 can satisfy: 90° < FOV < 115°, so that the optical system 100 has a large field of view, enabling the user to obtain a good immersive visual experience effect. Optionally, this relational expression can further satisfy 100°

[0075] < FOV < 110°, thereby, the field of view of the optical system is appropriate, and the visual experience effect of the user can be further improved.

[0076] In some embodiments, as can be seen from the foregoing, a first protective glass P1 may also be provided between the projection side of the optical system 100 and the projection-side surface S1 of the first lens L1. The first protective glass P1 may be a flat glass to protect the first lens L1. In this case, the optical system 100 satisfies the following relationship: 1.2 < TTL / ft2 < 1.7; where TTL is the distance from the projection-side surface of the first protective glass P1 to the image source surface of the optical system 100 on the optical axis, and ft2 is the focal length of the optical system 100 in the telephoto state. In this way, while realizing the miniaturized design of the optical system 100, the focal length of the optical system 100 can be reasonably configured. Optionally, the relationship may further satisfy 1.3 < TTL / ft < 1.55, so that the relationship between the total length of the optical system 100 and the focal length in the telephoto state can be further balanced, and the miniaturized design of the optical system 100 can be achieved.

[0077] In some embodiments, the optical system 100 satisfies the following relationship: 0.65 < IH / ft2 < 1.1; where IH is the image height corresponding to half of the maximum field angle of the optical system 100. When the optical system 100 satisfies 0.65 < IH / ft2 < 1.1, it can help provide a large viewing angle and strengthen the miniaturized design of the optical system 100 and the head-mounted device to which it is applied. Optionally, the relationship may further satisfy 0.75 < IH / ft2 < 1.1, so that while balancing the large field angle of the optical system 100, the miniaturized design of the optical system 100 can also be balanced.

[0078] In some embodiments, the optical system 100 satisfies the following relationship: 1.1 < D11 / IH < 1.8; where D11 is the maximum effective semi-aperture of the projection-side surface of the first lens. When this relationship is satisfied, the head aperture of the optical system 100 can be adapted to match a photosensitive chip with a large image surface, which is beneficial to improving the imaging resolution and enabling the optical system 100 to have a high-pixel effect. Optionally, the relationship may further satisfy 1.3 < D11 / IH < 1.6. In this way, the optical system 100 has higher resolution and better imaging effect.

[0079] In some embodiments, the optical system 100 satisfies the following relationship: 4 < f1 / ft2 < 11; where f1 is the focal length of the first lens. When the optical system 100 satisfies the relationship 4 < f1 / ft2 < 11, the ratio of the first lens L1 to the focal length of the optical system 100 can be reasonably controlled, so that the refractive power distribution of the first lens L1 in the optical system 100 is appropriate, which is beneficial to reducing the generation of aberration and avoiding problems in image correction of the optical system 100 due to excessive change in the refractive power of a certain lens. Optionally, the relationship further satisfies 6 < f1 / ft2 < 9. In this way, the refractive power of the first lens L1 is more appropriate, thus avoiding excessive change in the refractive power of the first lens L1.

[0080] In some embodiments, the optical system 100 satisfies the following relationship: 5 < |f2| / ft2; where f2 is the focal length of the second lens. Correspondingly, when the optical system 100 satisfies the relationship 5 < |f2| / ft2, the ratio of the second lens L2 to the focal length of the optical system 100 can be reasonably controlled, so that the refractive power distribution of the second lens L2 in the optical system 100 is appropriate, which is beneficial to reducing the generation of aberration and avoiding problems in image correction of the optical system 100 due to excessive change in the refractive power of a certain lens. Optionally, the relationship further satisfies 6 < |f2| / ft2. In this way, the refractive power of the second lens L2 is more appropriate, thus avoiding excessive change in the refractive power of the second lens L2.

[0081] In some embodiments, the optical system 100 satisfies the following relationship: 1.6 < f3 / ft2 < 3.2; f3 is the focal length of the third lens. Correspondingly, when the optical system 100 satisfies the relationship 1.6 < f3 / ft2 < 3.2, the ratio of the third lens L3 to the focal length of the optical system 100 can be reasonably controlled, so that the refractive power distribution of the third lens L3 in the optical system 100 is appropriate, which is beneficial to reducing the generation of aberration and avoiding problems in image correction of the optical system 100 due to excessive change in the refractive power of a certain lens. Optionally, the relationship further satisfies 1.8 < f3 / ft2 < 3. In this way, the refractive power of the third lens L3 is more appropriate, thus avoiding excessive change in the refractive power of the third lens L3.

[0082] In some embodiments, the optical system 100 satisfies the following relationship: 0.9 < ft2 / ft1 < 1.2; where ft2 is the focal length of the optical system in the telephoto state, and ft1 is the focal length of the optical system in the short focal state. Correspondingly, when the optical system 100 satisfies the relationship 0.9 < ft2 / ft1 < 1.2, the ratio of the focal lengths of the optical system 100 in the telephoto state and the short focal state can be reasonably controlled, so that while taking into account the optical power of the optical system 100, the miniaturized design of the optical system 100 can be maintained. Optionally, this relationship further satisfies 0.95 < ft2 / ft1 < 1.1. In this way, while the optical system 100 has a telephoto function, the miniaturized design can also be achieved.

[0083] In some embodiments, the optical system 100 satisfies the following relationship: 1.3 < CT3 / CT1 < 2.5; where CT1 is the thickness of the first lens L1 on the optical axis, and CT3 is the thickness of the third lens L3 on the optical axis. By controlling the ratio of the thicknesses of the third lens L3 and the first lens L1 on the optical axis, the ratio of the central thicknesses of the third lens L3 and the first lens L1 can be reasonably controlled within a reasonable range, so as to facilitate the control of the optical powers of the third lens L3 and the first lens L1, enabling the aberrations of the third lens L3 and the first lens L1 to compensate each other and reducing the aberration of the optical system 100. Optionally, this relationship can further satisfy 1.5 < CT3 / CT1 < 2.3. Thus, the aberration compensation effect between the third lens L3 and the first lens L1 is better, which is beneficial to further reducing the aberration of the optical system 100.

[0084] In some embodiments, the optical system 100 satisfies the following relationship: 0.8 < CT1 / CT2 < 2; where CT2 is the thickness of the second lens L2 on the optical axis, and CT1 is the thickness of the first lens L1 on the optical axis. By controlling the ratio of the thicknesses of the second lens L2 and the first lens L1 on the optical axis, the ratio of the central thicknesses of the second lens L2 and the first lens L1 can be reasonably controlled within a reasonable range, so as to facilitate the control of the optical powers of the second lens L2 and the first lens L1, enabling the aberrations of the second lens L2 and the first lens L1 to compensate each other and reducing the aberration of the optical system 100. Optionally, this relationship can further satisfy 1 < CT1 / CT2 < 1.8. In this way, the aberration compensation effect between the second lens L2 and the first lens L1 is better, which is beneficial to further reducing the aberration of the optical system 100.

[0085] In some embodiments, the optical system 100 satisfies the following relationship: 1.5 < CT3 / CT2 < 3; where CT3 is the thickness of the third lens L3 on the optical axis. By controlling the ratio of the thicknesses of the second lens L2 and the third lens L3 on the optical axis, the center thickness ratio of the second lens L2 and the third lens L3 can be reasonably controlled within a reasonable range, so as to facilitate the control of the optical powers of the second lens L2 and the third lens L3, enabling the aberrations of the second lens L2 and the third lens L3 to compensate each other and reducing the aberrations of the optical system 100. Optionally, this relationship can further satisfy 1.7 < CT3 / CT2 < 2.8. In this way, the aberration compensation effect of the second lens L2 and the third lens L3 is better, which is beneficial to further reducing the aberrations of the optical system 100.

[0086] In some embodiments, the optical system 100 satisfies the following relationship: 6 < (CT1 + CT2 + CT3) / (AT12 - AT23) < 10. Where AT23 is the distance on the optical axis from the image source side surface of the second lens L2 to the projection side surface of the third lens L3, and AT12 is the distance on the optical axis from the image source side surface of the first lens L1 to the projection side surface of the second lens L2. When the optical system 100 satisfies this relationship, the movement amount of the first lens L1 in the optical axis direction can be effectively controlled, avoiding the distance between the first lens L1 and the second lens L2 being too large or too small, enabling the light rays to have sufficient transmission space, and thus facilitating the convergence of light rays. In addition, the thicknesses of each lens and the intervals between the lenses can be reasonably controlled, avoiding assembly interference and reducing the assembly difficulty. Optionally, this relationship can further satisfy 7 < (CT1 + CT2 + CT3) / (AT12 - AT23) < 9, so that the assembly between the lenses of the optical system 100 is simpler.

[0087] In some embodiments, the optical system 100 satisfies the following relationship: 15 < CT2 / AT23. When the optical system satisfies the relationship 15 < CT2 / AT23, the thickness of the second lens L2 can be reasonably controlled, making the thickness of the second lens L2 and the distance between the second lens L2 and the third lens L3 reasonable, facilitating the assembly of the second lens L2 and the third lens L3, and avoiding assembly interference. Optionally, this relationship can further satisfy 20 < CT2 / AT23, so that the assembly between the lenses of the optical system 100 is simpler.

[0088] Optionally, as mentioned above, the projection-side surface S1 of the first lens L1 is fitted with a polarizing reflection structure and a first phase retardation film. Therefore, to facilitate installation, the projection-side surface S1 of the first lens L1 is a flat curved surface, and the radius of curvature R1 of the projection-side surface S1 at the optical axis satisfies: |R1|>80mm. That is, the projection-side surface S1 of the first lens L1 is relatively flat, which facilitates the installation of the polarizing reflection structure and the first phase retardation film, reducing the difficulty of installation.

[0089] In some embodiments, the optical system 100 satisfies the following relationship: |R1| / R2 < -2. Here, R2 is the radius of curvature of the image source-side surface S2 of the first lens L1 at the optical axis. When the optical system 100 satisfies the above relationship, it can effectively control the ratio of the radius of curvature of the projection-side surface S1 to the image source-side surface S2 of the first lens L1 at the optical axis, thereby effectively controlling the surface shape of the projection-side surface S1 and the image source-side surface S2 of the first lens L1. This helps to reduce the reflection of light between adjacent lenses, and thus reduces the ghost image intensity of the optical system 100. Optionally, this relationship can further satisfy |R1| / R2 < -3, which further helps to reduce the ghost image intensity of the optical system 100.

[0090] In some embodiments, the optical system 100 satisfies the following relationship: |R4| / R3 < -1. Here, R4 is the radius of curvature of the image source-side surface S4 of the second lens L2 at the optical axis, and R3 is the radius of curvature of the projection-side surface S3 of the second lens L2 at the optical axis. When the optical system 100 satisfies the relationship |R4| / R3 < -1, the ratio of the radii of curvature of the projection-side surface S3 to the image source-side surface S4 of the second lens L2 at the optical axis can be effectively controlled. This effectively controls the surface shape of the projection-side surface S3 and the image source-side surface S4 of the second lens L2, thereby reducing the reflection of light between adjacent lenses and thus lowering the ghost image intensity of the optical system 100. Optionally, this relationship can further satisfy |R4| / R3 < -1.3, which further helps to reduce the ghost image intensity of the optical system 100.

[0091] In some embodiments, the optical system 100 satisfies the following relationship: 4 < R5 / R6. Here, R5 is the radius of curvature of the projection-side surface S5 of the third lens L3 at the optical axis, and R6 is the radius of curvature of the image-source-side surface S6 of the third lens L3 at the optical axis. When the optical system 100 satisfies the relationship 4 < R5 / R6, the ratio of the radius of curvature of the projection-side surface S5 and the image-source-side surface S6 of the third lens L3 at the optical axis can be effectively controlled, thereby effectively controlling the surface shape of the projection-side surface S5 and the image-source-side surface S6 of the third lens L3. Furthermore, it is beneficial to reduce the reflection of light between adjacent lenses, and thus reduce the ghost image intensity of the optical system 100. Optionally, this relationship can further satisfy 5 < R5 / R6, which is further beneficial to reducing the ghost image intensity of the optical system 100.

[0092] The optical system 100 of the embodiment will be described in detail below with specific parameters.

[0093] Example 1

[0094] The structural schematic diagram and optical path diagram of the optical system 100 disclosed in the first embodiment of the present application are as Figure 1 shown. The optical system 100 includes a stop STO (i.e., the human eye pupil), a first protective glass P1, a first lens L1, a second lens L2, a third lens L3, a second protective glass P2, and an image-source surface IMG, which are sequentially arranged along the optical axis from the projection side to the image-source side.

[0095] A polarization reflection structure (not shown) and a first phase retardation plate (not shown) are provided on the projection-side surface S1 of the first lens L1, and a beam splitter element (not shown) is provided between the first lens L1 and the second lens L2.

[0096] Optionally, a second polarization reflection film (not shown) is provided between the protective glass 60 and the image-source-side surface S6 of the third lens L3, and a second phase retardation plate (not shown) is provided on the projection side of the second polarization reflection film.

[0097] Optionally, a polarizer and a second phase retardation plate are further provided between the image-source-side surface S2 of the first lens L1 and the projection-side surface S3 of the second lens L2. In this way, the deflection and conversion of light can be achieved, ensuring that the emitted light is circularly polarized light.

[0098] From Figure 1 it can be seen that Figure 1 (a) in Figure 1 is a schematic diagram of the optical system in the short focal state, Figure 1 (b) in Figure 1As can be seen from the example, in Embodiment 1, when the optical system 100 is in a short focal length state, the distance between the first lens L1 and the second lens L2 is the smallest, that is, the first lens L1 is closest to the second lens L2 at this time. When the optical system 100 is in a medium focal length state, the first lens L1 gradually moves away from the second lens L2 until the optical system 100 is in a long focal length state, at which point the distance between the first lens L1 and the second lens L2 is the largest, that is, the first lens L1 is furthest away from the second lens L2 at this time.

[0099] The parameters of the optical system 100 are given in Table 1 below. The elements along the optical axis of the optical system 100, from the projection side to the image source side, are arranged sequentially from top to bottom in Table 1. The first value in the "thickness" parameter column of the lens is the thickness of the lens on the optical axis, and the second value is the distance on the optical axis from the image source surface to the next surface of the lens. In Table 1, ft refers to the focal length of the optical system, FOV is the maximum field of view of the optical system, and TTL is the distance on the optical axis from the projection side surface S1 of the first lens L1 to the image source surface of the optical system. Except for FOV, which is in degrees, all other parameters in Table 1 are in mm. Since the first lens L1 is movable on the optical axis, Table 2 shows the values ​​of A and C in Table 1 for the short focal length, medium focal length, and long focal length states. Here, A refers to the distance on the optical axis between the image source side surface S2 of the first lens L1 and the projection side surface S3 of the second lens L2, and C refers to the virtual image distance. In addition, Table 2 also provides the focal length ft1 of the optical system 100 in the short focal length state, the focal length ft3 in the medium focal length state, and the focal length ft2 in the long focal length state. It should be understood that the unit of each parameter in Table 2 is mm.

[0100] Furthermore, each surface of the first lens L1 to the third lens L3 can be aspherical, wherein the surface shape x of the aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0101]

[0102] Where z is the distance vector from the vertex of the aspherical surface at a height of h along the optical axis; c is the curvature of the aspherical surface at the optical axis, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); K is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 3 below gives the coefficients of each aspherical surface that can be used in Example 1, where coefficients not given are 0.

[0103] Furthermore, the first lens L1 has positive refractive power, and its projection-side surface S1 and image-source-side surface S2 are both convex near the optical axis. The second lens L2 has negative refractive power, and both its projection-side surface S3 and image-source-side surface S4 are concave near the optical axis. The third lens L3 has positive refractive power, and both its projection-side surface S5 and image-source-side surface S6 are convex near the optical axis.

[0104] Furthermore, the projection-side surface and image-source-side surface of the first lens L1 to the third lens L3 are both aspherical.

[0105] Table 1

[0106]

[0107]

[0108] Table 2

[0109] parameter Short focal length Middle Jiao state Telephoto mode A 0.32 0.79 1.99 C -125.00 -600.00 -1000.00 ft 14.15 14.23 14.43

[0110] Table 3

[0111]

[0112] Please refer to 2. Figure 2 The aberration and distortion curves of the optical system 100 are shown. Figure 2 Figure (A) shows astigmatism curves at wavelengths of 456 nm, 531 nm, and 640 nm. The horizontal axis along the X-axis represents focus shift, and the vertical axis along the Y-axis represents image height, in mm. The field curvature curves represent the curvature of the meridional and sagittal imaging planes. As can be seen from the figure, the field curvature of optical system 100 is small, and the field curvature and astigmatism of each field of view are well corrected, with clear imaging at both the center and edges of the field of view.

[0113] Please see Figure 2 (B) in the middle Figure 2 Figure (B) shows the distortion curves of the optical system 100 in this embodiment at wavelengths of 456 nm, 531 nm, and 640 nm. The horizontal axis along the X-axis represents distortion, and the vertical axis along the Y-axis represents image height, in mm. Figure 2 As can be seen from (B) in the figure, the distortion of the optical system 100 is well corrected at a wavelength of 623nm.

[0114] Please see Figure 3 , Figure 3The diagram shows the spherical aberration curves of the optical system 100 at wavelengths of 456 nm, 531 nm, and 640 nm. In the figure, the horizontal axis along the X-axis represents the focus shift, and the vertical axis along the Y-axis represents the normalized field of view. Figure 3 It can be seen that the spherical aberration value of the optical system 100 in this embodiment is better, indicating that the imaging quality of the optical system 100 in this embodiment is better.

[0115] Example 2

[0116] A schematic diagram of the optical system 100 disclosed in Embodiment 2 of this application is shown below. Figure 4 As shown, the optical system 100 includes an aperture stop STO (i.e., the pupil of a human eye), a first protective glass P1, a first lens L1, a second lens L2, a third lens L3, a second protective glass P2, and an image source surface IMG arranged sequentially along the optical axis from the projection side to the image source side.

[0117] In the second embodiment, Figure 4 (a) in the diagram is a schematic of the optical system in a short focal length state. Figure 4 (b) in the diagram is a schematic diagram of the optical system in the central focal state. Figure 4 (c) in the diagram is a schematic of the optical system in telephoto mode. From Figure 4 As can be seen, when the optical system 100 is in a short focal length state, the distance between the first lens L1 and the second lens L2 is the smallest, that is, the first lens L1 is closest to the second lens L2 at this time. When the optical system 100 is in a medium focal length state, the first lens L1 gradually moves away from the second lens L2 until the optical system 100 is in a long focal length state, at which point the distance between the first lens L1 and the second lens L2 is the largest, that is, the first lens L1 is furthest away from the second lens L2 at this time.

[0118] The refractive power of the first lens L1 to the third lens L3 is the same as that in Embodiment 1. Among the first lens L1 to the third lens L3, except that the projection side surface S1 of the first lens L1 and the image source side surface S4 of the second lens L2 are convex near the optical axis, the other lens surface designs are the same as those in Embodiment 1.

[0119] As shown in Table 4 below, the definitions of each parameter in Table 4 can be derived from the description of Table 1 in Example 1, and will not be repeated here. It should be understood that the units for radius of curvature, thickness, and focal length in Table 4 are all mm. For the interpretation of Tables 5 and 6, please refer to the descriptions of Tables 2 and 3 in Example 1, and will not be repeated here.

[0120] Table 4

[0121]

[0122] Table 5

[0123]

[0124]

[0125] Table 6

[0126]

[0127] Please see Figure 5 , Figure 5 The aberration and distortion curves of the optical system 100 are shown. Figure 5 (A) Figure 5 The wavelengths corresponding to each curve in (B) can be found in Example 1 regarding... Figure 2 (A) Figure 2 The content described in (B) will not be repeated here.

[0128] Please see Figure 6 , Figure 6 The transverse chromatic aberration curve of the optical system is shown, from... Figure 6 As can be seen, the spherical aberration value of the optical system 100 in this embodiment is better, indicating that the imaging quality of the optical system 100 in this embodiment is better. Furthermore, regarding... Figure 6 The wavelengths corresponding to each curve can be referred to in Example 1. Figure 3 As previously mentioned, this will not be repeated here.

[0129] Example 3

[0130] A schematic diagram of the optical system 100 disclosed in Embodiment 3 of this application is shown below. Figure 7 As shown, the optical system 100 includes an aperture stop STO (i.e., the pupil of a human eye), a first protective glass P1, a first lens L1, a second lens L2, a third lens L3, a second protective glass P2, and an image source surface IMG arranged sequentially along the optical axis from the projection side to the image source side.

[0131] from Figure 7 From this, we can know that Figure 7 (a) in the diagram is a schematic of the optical system in a short focal length state. Figure 7 (b) in the diagram is a schematic diagram of the optical system in the central focal state. Figure 7 (c) in the diagram is a schematic of the optical system in telephoto mode. From Figure 7As can be seen from the example, in Embodiment 1, when the optical system 100 is in a short focal length state, the distance between the first lens L1 and the second lens L2 is the smallest, that is, the first lens L1 is closest to the second lens L2 at this time. When the optical system 100 is in a medium focal length state, the first lens L1 gradually moves away from the second lens L2 until the optical system 100 is in a long focal length state, at which point the distance between the first lens L1 and the second lens L2 is the largest, that is, the first lens L1 is furthest away from the second lens L2 at this time.

[0132] The first lens L1 has positive refractive power, and the second lens L2 and the third lens L3 also have positive refractive power. In the surface design of the first lens L1 to the third lens L3, except that the image source side surface S4 of the second lens L2 is convex near the optical axis, the surface shapes of the other lenses are the same as in Embodiment 1, and will not be described again here.

[0133] As shown in Table 7 below, the definitions of each parameter in Table 7 can be derived from the description of Table 1 in Example 1, and will not be repeated here. It should be understood that the units for radius of curvature, thickness, and focal length in Table 7 are all mm. For the interpretation of Tables 8 and 9, please refer to the descriptions of Tables 2 and 3 in Example 1, and will not be repeated here.

[0134] Table 7

[0135]

[0136]

[0137] Table 8

[0138] parameter Short focal length Middle Jiao state Telephoto mode A 0.38 0.83 1.96 C -125.00 -600.00 -1000.00 ft 13.4 13.60 13.90

[0139] Table 9

[0140]

[0141] Please see Figure 8 , Figure 8 The aberration and distortion curves of the optical system 100 are shown. Figure 8 (A) Figure 8 The wavelengths corresponding to each curve in (B) can be found in Example 1 regarding... Figure 2 (A) Figure 2 The content described in (B) will not be repeated here.

[0142] Please see Figure 9 , Figure 9 The transverse chromatic aberration curve of the optical system is shown, from... Figure 9 As can be seen, the spherical aberration value of the optical system 100 in this embodiment is better, indicating that the imaging quality of the optical system 100 in this embodiment is better. Furthermore, regarding... Figure 9The wavelengths corresponding to each curve can be referred to in Example 1. Figure 3 As previously mentioned, this will not be repeated here.

[0143] Example 4

[0144] A schematic diagram of the optical system 100 disclosed in Embodiment 4 of this application is shown below. Figure 10 As shown, the optical system 100 includes an aperture stop STO (i.e., the pupil of a human eye), a first protective glass P1, a first lens L1, a second lens L2, a third lens L3, a second protective glass P2, and an image source surface IMG arranged sequentially along the optical axis from the projection side to the image source side.

[0145] from Figure 10 From this, we can know that Figure 10 (a) in the diagram is a schematic of the optical system in a short focal length state. Figure 10 (b) in the diagram is a schematic diagram of the optical system in the central focal state. Figure 10 (c) in the diagram is a schematic of the optical system in telephoto mode. From Figure 10 As can be seen from the example, in Embodiment 1, when the optical system 100 is in a short focal length state, the distance between the first lens L1 and the second lens L2 is the largest, that is, the first lens L1 is furthest away from the second lens L2 at this time. When the optical system 100 is in a medium focal length state, the first lens L1 gradually moves closer to the second lens L2 until the optical system 100 is in a long focal length state, at which point the distance between the first lens L1 and the second lens L2 is the smallest, that is, the first lens L1 is closest to the second lens L2 at this time.

[0146] In this embodiment, the refractive power of the first lens L1 to the third lens L3 is the same as in Embodiment 1. In the surface design of the first lens L1 to the third lens L3, except that the projection side surface S1 of the first lens L1 is concave and the image source side surface S4 of the second lens L2 is convex near the optical axis, the surface designs of the other lenses are the same as in Embodiment 1, and will not be described again here.

[0147] As shown in Table 10 below, the definitions of each parameter in Table 10 can be derived from the description of Table 1 in Example 1, and will not be repeated here. It should be understood that the units of radius of curvature, thickness, and focal length in Table 10 are all mm. For the interpretation of Tables 11 and 12, please refer to the descriptions of Tables 2 and 3 in Example 1, and will not be repeated here.

[0148] Table 10

[0149]

[0150] Table 11

[0151] parameter Short focal length Middle Jiao state Telephoto mode A 0.43 0.88 2.00 C -125.00 -600.00 -1000.00 ft 13.58 13.69 13.97

[0152] Table 12

[0153]

[0154] Please see Figure 11 , Figure 11 The aberration and distortion curves of the optical system 100 are shown. Figure 11 (A) Figure 11 The wavelengths corresponding to each curve in (B) can be found in Example 1 regarding... Figure 2 (A) Figure 2 The content described in (B) will not be repeated here.

[0155] Please see Figure 12 , Figure 12 The transverse chromatic aberration curve of the optical system is shown, from... Figure 12 As can be seen, the spherical aberration value of the optical system 100 in this embodiment is better, indicating that the imaging quality of the optical system 100 in this embodiment is better. Furthermore, regarding... Figure 12 The wavelengths corresponding to each curve can be referred to in Example 1. Figure 3 As previously mentioned, this will not be repeated here.

[0156] Example 5

[0157] A schematic diagram of the optical system 100 disclosed in Embodiment 5 of this application is shown below. Figure 13 As shown, the optical system 100 includes an aperture stop STO (i.e., the pupil of a human eye), a first protective glass P1, a first lens L1, a second lens L2, a third lens L3, a second protective glass P2, and an image source surface IMG arranged sequentially along the optical axis from the projection side to the image source side.

[0158] The refractive forces of the first lens L1 to the third lens L3 are described in Example 1 and will not be repeated here.

[0159] In Embodiment 5, the surface design of the first lens L1 to the third lens L3 is the same as that of Embodiment 1, except that the image source side surface S4 of the second lens L2 is convex near the optical axis. Therefore, it will not be described again here.

[0160] from Figure 13 From this, we can know that Figure 13 (a) in the diagram is a schematic of the optical system in a short focal length state. Figure 13 (b) in the diagram is a schematic diagram of the optical system in the central focal state. Figure 13 (c) in the diagram is a schematic of the optical system in telephoto mode. From Figure 13As can be seen from the example, in Embodiment 1, when the optical system 100 is in a short focal length state, the distance between the first lens L1 and the second lens L2 is the largest, that is, the first lens L1 is furthest away from the second lens L2 at this time. When the optical system 100 is in a medium focal length state, the first lens L1 gradually moves closer to the second lens L2 until the optical system 100 is in a long focal length state, at which point the distance between the first lens L1 and the second lens L2 is the smallest, that is, the first lens L1 is closest to the second lens L2 at this time.

[0161] In this embodiment, the refractive power of the first lens L1 to the third lens L3 is the same as in Embodiment 1. In the surface design of the first lens L1 to the third lens L3, except that the projection side surface S1 of the first lens L1 is concave and the image source side surface S4 of the second lens L2 is convex near the optical axis, the surface designs of the other lenses are the same as in Embodiment 1, and will not be described again here.

[0162] As shown in Table 13 below, the definitions of each parameter in Table 13 can be derived from the description of Table 1 in Example 1, and will not be repeated here. It should be understood that the units of radius of curvature, thickness, and focal length in Table 10 are all mm. For the interpretation of Tables 14 and 15, please refer to the descriptions of Tables 2 and 3 in Example 1, and will not be repeated here.

[0163] Table 13

[0164]

[0165]

[0166] Table 14

[0167] parameter Short focal length Middle Jiao state Telephoto mode A 0.43 0.88 2.00 C -125.00 -600.00 -1000.00 ft 13.874 13.55 13.43

[0168] Table 15

[0169]

[0170] Please see Figure 14 , Figure 14 The aberration and distortion curves of the optical system 100 are shown. Figure 14 (A) Figure 14 The wavelengths corresponding to each curve in (B) can be found in Example 1 regarding... Figure 2 (A) Figure 2 The content described in (B) will not be repeated here.

[0171] Please see Figure 15 , Figure 15 The transverse chromatic aberration curve of the optical system is shown, from... Figure 15As can be seen, the spherical aberration value of the optical system 100 in this embodiment is better, indicating that the imaging quality of the optical system 100 in this embodiment is better. Furthermore, regarding... Figure 15 The wavelengths corresponding to each curve can be referred to in Example 1. Figure 3 As previously mentioned, this will not be repeated here.

[0172] Please refer to Table 16, which is a summary of the ratios of various relationships in Embodiments 1 to 6 of this application.

[0173] Table 16

[0174]

[0175]

[0176] Secondly, please refer to Figure 16 This application also discloses a head-mounted device 200, which includes a housing 201, a display (not shown), and an optical system 100 as described in the first aspect above. The display and the optical system 100 are disposed in the housing 201, and the display is located on the image source side of the optical system 100. Specifically, when the optical system 100 is disposed in the housing 201, it may be disposed within the housing 201. Optionally, the head-mounted device 200 may include, but is not limited to, AR glasses, AR helmets, etc.

[0177] The foregoing has provided a detailed description of an optical system and head-mounted device disclosed in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the optical system and head-mounted device of this application and their core ideas. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An optical system, characterized in that, There are three lenses with refractive power in total. The optical system includes, in sequence, the following along the optical axis from the projection side to the image source side: The first lens has positive refractive power, and the image source side surface of the first lens is convex near the optical axis. The first lens is movable along the optical axis. The second lens has refractive power, and the projection side surface of the second lens is concave near the optical axis; The third lens has positive refractive power, and both the projection side surface and the image source side surface of the third lens are convex near the optical axis. Between the projection-side surface of the first lens and the image-source-side surface of the optical system, along the optical axis from the projection side to the image-source side, a polarization reflection structure, a first phase retardation plate, and a beam splitter are sequentially provided on the surface. The first phase retardation plate and the beam splitter are located on the projection side and the image-source side of the first lens, respectively. The optical system satisfies the following relationship: 4 < f1 / ft2 < 11; 5 < |f²| / ft² ≤ 143.451; 1.6 < f3 / ft2 < 3.2; 1.3 < CT3 / CT1 < 2.5; 1.5 < CT3 / CT2 < 3; 0.8 < CT1 / CT2 < 2; Wherein, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, ft2 is the focal length of the optical system in telephoto mode, CT2 is the thickness of the second lens on the optical axis, CT1 is the thickness of the first lens on the optical axis, and CT3 is the thickness of the third lens on the optical axis.

2. The optical system according to claim 1, characterized in that, The refractive power adjustment range of the optical system is 0D-8D.

3. The optical system according to claim 1, characterized in that, The optical system further includes a first protective glass, which is located between the projection side of the optical system and the projection side surface of the first lens. The optical system satisfies the following relationship: 1.2 < TTL / ft2 < 1.7; Wherein, TTL is the distance on the optical axis from the projection side surface of the first protective glass to the image source surface of the optical system.

4. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationship: 0.65 < IH / ft2 < 1.1, and / or, 1.1 < D11 / IH < 1.8; Wherein, IH is the image height corresponding to half of the maximum field of view of the optical system, and D11 is the maximum effective half-aperture of the projection side surface of the first lens.

5. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationship: 0.9 < ft2 / ft1 < 1.2; Wherein, ft1 is the focal length of the optical system in the short focal length state.

6. The optical system according to claim 1, characterized in that, The projection side surface of the first lens is a flat curved surface, and the radius of curvature R1 of the projection side surface of the first lens at the optical axis satisfies: |R1|>80.

7. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationships: |R1| / R2 < -2, and / or, |R4| / R3 < -1, and / or, 4 < R5 / R6; Wherein, R1 is the radius of curvature of the projection-side surface of the first lens at the optical axis, R2 is the radius of curvature of the image-source-side surface of the first lens at the optical axis, R4 is the radius of curvature of the image-source-side surface of the second lens at the optical axis, R3 is the radius of curvature of the projection-side surface of the second lens at the optical axis, R5 is the radius of curvature of the projection-side surface of the third lens at the optical axis, and R6 is the radius of curvature of the image-source-side surface of the third lens at the optical axis.

8. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationship: 15 < CT2 / AT23, and / or, 6 < (CT1 + CT2 + CT3) / (AT12 - AT23) < 10; Wherein, AT23 is the distance on the optical axis from the image source side surface of the second lens to the projection side surface of the third lens, and AT12 is the distance on the optical axis from the image source side surface of the first lens to the projection side surface of the second lens.

9. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationship: 90° < FOV < 115°; Wherein, FOV is the maximum field of view of the optical system.

10. A head-mounted device, characterized in that, The head-mounted device includes a housing, a display, and an optical system as described in any one of claims 1-9, wherein the display and the optical system are disposed in the housing, and the display is located on the image source side of the optical system.

Images