Optical system and head-mounted device

Abstract

The invention 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 in order from a projection side to an image source side, the first lens has positive refractive power, the image source side surface of the first lens is a convex surface near the optical axis, the first lens is movable in the optical axis direction, the second lens has refractive power, and the third lens is a convex surface near the optical axis. The projection side surface of the third lens is a concave surface near the optical axis, the third lens has positive refractive power, and the projection side surface and the image source side surface of the third lens are convex surfaces near the optical axis; a polarization reflection structure, a first phase delay piece and a light splitting element are sequentially arranged between the projection side surface of the first lens and the image source side surface of the optical system from the projection side to the image source side surface along the optical axis, and the first phase delay piece and the light splitting element are located on the projection side and the image source side of the first lens respectively. According to the optical system and the head-mounted device, the myopia degrees of different users can be adapted on the basis of realizing miniaturization design.

Description

Technical Field

[0001] The present application relates to the field of optical imaging technology, and in particular to an optical system and a head-mounted device. Background Art

[0002] With the advancement of technology and the needs of social and economic development, virtual reality technology has developed rapidly, and head-mounted devices using virtual reality technology (such as VR glasses) have emerged. Due to the limitation of magnification, the optical system in conventional head-mounted devices usually has a long size, which is not conducive to the miniaturization design of the optical system itself, and is therefore not suitable for miniaturized head-mounted devices. On the other hand, due to the different degrees of myopia among different users, the optical systems in most head-mounted devices do not have the function of adjusting according to the degree of myopia of the user, which affects the user experience. Summary of the invention

[0003] The embodiments of the present application disclose an optical system and a head-mounted device, which can adapt to the myopia levels of different users on the basis of realizing a miniaturized design, thereby effectively improving the user experience.

[0004] In order to achieve the above objectives, in a first aspect, the present application discloses an optical system, which has three lenses with refractive power, and the optical system includes, in order from the projection side to the image source side along the optical axis:

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

[0006] A second lens having a refractive power, wherein a projection side surface of the second lens is a concave surface at a near optical axis;

[0007] A third lens has positive refractive power, and a projection side surface and an image source side surface of the third lens are both convex surfaces at the near optical axis;

[0008] 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 delay plate and a beam splitter are sequentially provided on the surface from the projection side to the image source side along the optical axis. The first phase delay plate and the beam splitter are respectively located on the projection side and the image source side of the first lens.

[0009] By setting three lenses with refractive power, the polarization refraction, transmission, and reflection of the light path in the optical system can be achieved with a limited number of lenses in combination with the setting of the polarization reflection structure, the first phase delay plate, and the beam splitter element, thereby achieving the deflection and folding of the light path with a limited number of lenses, without increasing the number of lenses, effectively reducing the overall volume of the optical system, and thus facilitating the thin and light miniaturization design of the optical system. At the same time, by setting the optical system to also include a beam splitter element, and the beam splitter element is located on the image source side of the first lens, it is possible to better focus the light within a large viewing angle range to the beam splitter element for transmission or reflection, which is conducive to matching the large-size image source surface, thereby expanding the field of view.

[0010] In addition, by providing a first lens with positive refractive power, and the projection side surface of the first lens is convex at the near optical axis, the second lens has refractive power, and the projection side surface of the second lens is concave at the near optical axis, and the third lens has positive refractive power, and the projection side surface and image source side surface of the third lens are convex at the near optical axis, the design can facilitate the entry of light into the optical system, thereby better focusing the light within a large viewing angle range, which is conducive to matching a large-size image source surface, and thus expanding the field of view.

[0011] Furthermore, the optical system of the present application is also movable along the optical axis direction of the optical system through the first lens, so that the optical system can adjust the movement of the third lens along the optical axis direction according to the myopia degree of different users, and then achieve focusing, thereby adapting to the myopia degree of different users and improving the user experience.

[0012] As an optional implementation, the diopter adjustment range of the optical system is 0D-8D, so that the optical system can be adapted to the myopia focal length range of 0-500 degrees, and is adapted to the myopia population of 0-500 degrees, and in the process of the first lens moving and focusing, the optical system can maintain the quality of the image within 120° of the center and edge viewing angles, ensuring the imaging clarity of the optical system. Exceeding the range of the relationship will cause the first lens to move too much or too little in the direction of the optical axis, on the one hand, causing interference between optical elements or ineffective use of the arrangement space between lenses, which is not conducive to the thinness and miniaturization of the optical system; on the other hand, the focal length adjustment of the optical system cannot be effectively controlled, affecting the imaging clarity of the optical system and reducing the image quality.

[0013] As an optional implementation, the optical system further includes a first protective glass, and the first protective glass is 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; wherein TTL is the distance from the projection side surface of the first protective glass to the image source surface of the optical system on the optical axis, and ft2 is the focal length of the optical system in a telephoto state. In this way, the focal length of the optical system can be reasonably configured while realizing the miniaturization design of the optical system.

[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 angle of the optical system, ft2 is the focal length of the optical system in a telephoto state, and D11 is the maximum effective semi-aperture of the projection side surface of the first lens.

[0017] When the optical system satisfies 0.65<IH / ft<1.1, it can help provide a large viewing angle 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 head aperture of the optical system can be adapted to match the photosensitive chip with a large image surface, which is beneficial to improving the imaging resolution and making the optical system have a high pixel effect.

[0019] As an optional implementation, the optical system satisfies the following relationship: <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] Among them, 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 a telephoto state, and ft1 is the focal length of the optical system in a short focal state.

[0021] When the optical system satisfies the above relationship, the ratio of the focal length of each lens to the optical system can be reasonably controlled so that the refractive power of each lens in the optical system is appropriately distributed, which is beneficial to slowing down the generation of aberrations and avoiding image correction problems in 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 curvature radius 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 is conducive to the attachment of the first phase retarder and reduces the difficulty of attachment.

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

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

[0025] When the optical system satisfies the above relationship, the ratio of the curvature radius of the projection side surface of each lens to the image source side surface of each lens at the optical axis can be effectively controlled, thereby effectively controlling the surface shape of the projection side surface and the image source side surface of each lens, which is beneficial to reduce the reflection of light between two adjacent lenses, thereby reducing 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] Among them, 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 from the image source side surface of the second lens to the projection side surface of the third lens on the optical axis, and AT12 is the distance from the image source side surface of the first lens to the projection side surface of the second lens on the optical axis.

[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 central thickness of each lens can be reasonably controlled, so as to facilitate the control of the optical focal length of each lens, so that the aberrations of each lens can compensate each other, reduce the aberration of the optical system, and help 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, so that the thickness of the second lens and the distance between the second lens and the third lens are reasonable, which facilitates the assembly of the second lens and the third lens and avoids assembly interference.

[0030] Since the first lens is movable in the direction of the optical axis, when the optical system satisfies the relationship 6<(CT1+CT2+CT3) / (AT12-AT23)<10, the movement of the first lens in the direction of the optical axis can be effectively controlled to avoid the spacing between the first lens and the second lens being too large or too small, so that the light has enough transmission space, thereby facilitating the convergence of the light. In addition, the thickness of each lens and the spacing between the lenses can be reasonably controlled to avoid assembly interference and reduce the difficulty of assembly.

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

[0032] When the optical system satisfies the above relationship, wide viewing angle imaging of the optical system can be achieved.

[0033] In a second aspect, the present application further discloses a head-mounted device, which includes a shell, a display, and the optical system as described in the first aspect above, wherein the display and the optical system are arranged in the shell, 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:

[0035] By setting three lenses with refractive power, the polarization refraction, transmission, and reflection of the light path in the optical system can be achieved with a limited number of lenses in combination with the setting of the polarization reflection structure, the first phase delay plate, and the beam splitter element, thereby achieving the deflection and folding of the light path with a limited number of lenses, without increasing the number of lenses, effectively reducing the overall volume of the optical system, and thus facilitating the thin and light miniaturization design of the optical system. At the same time, by setting the optical system to also include a beam splitter element, and the beam splitter element is located on the image source side of the first lens, it is possible to better focus the light within a large viewing angle range to the beam splitter element for transmission or reflection, which is conducive to matching the large-size image source surface, thereby expanding the field of view.

[0036] In addition, by providing a first lens with positive refractive power, and the projection side surface of the first lens is convex at the near optical axis, the second lens has refractive power, and the projection side surface of the second lens is concave at the near optical axis, and the third lens has positive refractive power, and the projection side surface and image source side surface of the third lens are convex at the near optical axis, the design can facilitate the entry of light into the optical system, thereby better focusing the light within a large viewing angle range, which is conducive to matching a large-size image source surface, and thus expanding the field of view.

[0037] Furthermore, the optical system of the present application is also movable along the optical axis direction of the optical system through the first lens, so that the optical system can adjust the movement of the third lens along the optical axis direction according to the myopia degree of different users, and then achieve focusing, thereby adapting to the myopia degree of different users and improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 is a schematic structural diagram of an optical system disclosed in Example 1 of the present application;

[0040] Figure 2 is an astigmatism and distortion curve diagram of the optical system disclosed in Example 1 of the present application;

[0041] Figure 3 is a spherical aberration curve diagram of the optical system disclosed in Example 1 of the present application;

[0042] Figure 4 is a schematic diagram of the structure of the optical system disclosed in Example 2 of the present application;

[0043] Figure 5 is an astigmatism and distortion curve diagram of the optical system disclosed in Example 2 of the present application;

[0044] Figure 6 is a spherical aberration curve diagram of the optical system disclosed in Example 2 of the present application;

[0045] Figure 7 is a schematic diagram of the structure of the optical system disclosed in Example 3 of the present application;

[0046] Figure 8 is an astigmatism and distortion curve diagram of the optical system disclosed in Example 3 of the present application;

[0047] Fig. 9 is a spherical aberration curve diagram of the optical system disclosed in Example 3 of the present application;

[0048] Fig.10 is a schematic diagram of the structure of the optical system disclosed in Example 4 of the present application;

[0049] Fig.11 is an astigmatism and distortion curve diagram of the optical system disclosed in Example 4 of the present application;

[0050] Fig.12is a spherical aberration curve diagram of the optical system disclosed in Example 4 of the present application;

[0051] Fig.13 is a schematic diagram of the structure of the optical system disclosed in Example 5 of the present application;

[0052] Fig.14 is an astigmatism and distortion curve diagram of the optical system disclosed in Example 5 of the present application;

[0053] Fig.15 is a spherical aberration curve diagram of the optical system disclosed in Example 5 of the present application;

[0054] Fig.16 It is a schematic diagram of the structure of the head-mounted device disclosed in this application. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0056] The technical solution of the present application will be further described below in conjunction with embodiments and drawings.

[0057] See also Figure 1 , Figure 1 is a schematic diagram of the optical system. Figure 1 (a) is a schematic diagram of the optical system in a short-focus state. Figure 1 (b) is a schematic diagram of the optical system in the mid-focus state. Figure 1 (c) is a schematic diagram of the optical system in a telephoto state. According to the first aspect of the present application, the present application discloses an optical system 100, which has three lenses with refractive power. Along the optical axis from the projection side to the image source side, the optical system 100 includes a first lens L1, a second lens L2 and a third lens L3 in sequence. Among them, the first lens L1 has positive refractive power, the second lens L2 has positive refractive power or negative refractive power, and the third lens L3 has positive refractive power. Among them, the first lens L1 is movable along the optical axis direction, so that the focusing function of the optical system can be realized, so that it can be adapted to users with different degrees of myopia.

[0058] It can be understood that the optical system 100 can be applied to a head-mounted device, and 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 refers to the side facing, for example, the display of the head-mounted device.

[0059] It is understandable that Figure 1 It can be seen that when the optical system switches from the short focus state to the long focus state, the first lens L1 is moved in the optical axis direction so that the first lens L1 is away from the second lens L2, that is, the distance between the first lens L1 and the second lens L2 on the optical axis is increased. That is, 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 is increased, and in the long focus state, the distance between the first lens L1 and the second lens L2 is the largest. Of course, as other embodiments, the distance between the first lens L1 and the second lens L2 on the optical axis can also be reduced when the optical system 100 switches from the short focus state to the long focus state. That is, in the short focus state, the first lens L1 is farthest from the second lens L2, in the medium focus state, the distance between the first lens L1 and the second lens L2 is reduced, and in the long focus state, the distance between the first lens L1 and the second lens L2 is the smallest.

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

[0061] By configuring the optical system 100 to further include a beam splitter, and the beam splitter is located on the image source side of the first lens L1, light within a large viewing angle range can be better focused onto the beam splitter for transmission or reflection, which is beneficial for matching a large-sized image source surface and thereby expanding the field of view.

[0062] It can be understood that, as long as the polarization reflection structure, the first phase delay plate 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 delay plate and the beam splitter are respectively located on the projection side and the image source side of the first lens L1, the present embodiment does not make any specific limitation on the specific arrangement positions.

[0063] For example, when the polarization reflection structure is arranged between the projection side and the projection side surface S1 of the first lens L1, the first phase delay plate can be arranged between the polarization reflection structure and the projection side surface S1 of the first lens L1, and at the same time, the splitter element can be arranged on the image source side surface S2 of the first lens L1.

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

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

[0066] Optionally, a lens may be provided between the first phase retarder and the beam splitter on the surface from the projection side to the image source side along the optical axis. That is, the beam splitter may be provided on the image source side surface S2 of the first lens L1, or a flat glass may be provided between the second lens L2 and the first lens L1, and then the beam splitter may be provided on the flat glass, 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 , and the second protective glass P2 is disposed between the image source side surface S6 of the third lens L3 and the image source plane of the optical system 100 .

[0068] In addition, the optical system may further include a second phase retarder and a polarizer. The second phase retarder may be attached to a second protective glass P2 on the image source of the optical system, or may be arranged 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, the second phase retarder may be directly attached to the projection side surface of the second lens L2, or 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 the present application is briefly described below.

[0070] like Figure 1As shown, when the light is imaged along the light path direction, the light emitted from the image source surface IMG (generally the display screen of the head-mounted device) is the first circularly polarized light. For example, the display screen of the head-mounted device generally includes a linear polarizer and a phase delay plate, so that the light emitted from the image source surface IMG of the display screen is the first circularly polarized light; further, a polarization reflection structure, a first phase delay plate and a spectroscopic element are sequentially provided from the projection side to the image source side. Exemplarily, the polarization reflection structure is provided on the projection side and the projection side surface S1 of the first lens L1, the first phase delay plate is provided on the projection side surface S1 of the first lens L1, the first phase delay plate is preferably a quarter-wave plate, and the spectroscopic element is provided on the projection side surface S3 of the second lens L2, and the spectroscopic element is preferably a semi-reflective and semi-transparent film, so that the first circularly polarized light passes through the third lens L3, the second lens L2, the spectroscopic element and the image of the first lens L1 in sequence. The source side surface S2 is transmitted, and is reflected by the projection side surface S1 of the first lens L1 and the polarization reflection structure thereon and the first phase delay plate, so that the first circularly polarized light is changed into the first linearly polarized light; the first linearly polarized light passes through the second lens L2, is reflected by the beam splitter on the projection side surface S3 of the second lens L2, and passes through the first phase delay plate on the first lens L1 again. Under the action of the first phase delay plate, the first linearly polarized light is changed into the second circularly polarized light; the deflection direction of the second circularly polarized light is opposite to the deflection direction of the first circularly polarized light, so that the second circularly polarized light is reflected by the beam splitter on the projection side surface S3 of the second lens L2 again, passes through the first phase delay plate on the first lens L1, and is changed from the second circularly polarized light to the second linearly polarized light. After the second linearly polarized light passes through the polarization reflection structure and the first protective glass P1, it is transmitted to the projection surface, that is, the virtual reality device completes imaging in the human eye.

[0071] In some embodiments, the projection side surface S1 of the first lens L1 may be a concave surface or a convex surface at the near optical axis, the image source side surface S2 of the first lens L1 may be a convex surface at the near optical axis, the projection side surface S3 of the second lens L2 may be a concave surface at the near optical axis, and the image source side surface S4 of the second lens L2 may be a convex surface or a concave surface at the near optical axis. The projection side surface S5 of the third lens L3 may be a convex surface at the near optical axis, and the image source side surface S6 of the third lens L3 may be a convex surface at the near optical axis. The projection side surfaces of the above lenses are all facing the human eye, and the image source side surfaces of the above lenses are all facing 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 thin and light property 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 also be set as glass lenses and some lenses can be plastic lenses, and the specific settings can be adjusted according to the actual situation. This embodiment does not make specific limitations on this.

[0073] Optionally, as can be seen from the foregoing, the first lens L1 can move 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 adjustment process of the first lens L1, the optical system 100 can maintain the quality of the images within a central and peripheral viewing angle of less than 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 utilization of the arrangement space between the lenses, which is not conducive to the thin, light, 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 relatively large field of view, enabling users 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, which can further improve the visual experience effect of users.

[0076] In some embodiments, as described above, a first protective glass P1 may be further disposed 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 long focal length 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 long focal length state can be further balanced, and the miniaturized design of the optical system 100 can be realized.

[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 of view angle of the optical system 100. When the optical system 100 satisfies 0.65 < IH / ft2 < 1.1, it can help to 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 of view 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 the photosensitive chip with a large image plane, 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 a higher resolution and a 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 conducive 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, thereby 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 conducive 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, thereby 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 conducive 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, thereby 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 wide-angle state. Accordingly, 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 wide-angle 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, the 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 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, the 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, the 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 central thickness ratio of the second lens L2 and the third lens L3 can be reasonably controlled within a reasonable range, thereby facilitating 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 for each other, and reducing the aberrations of the optical system 100. Optionally, this relationship may further satisfy 1.7 < CT3 / CT2 < 2.8, so that the aberration compensation effect between 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 sufficient transmission space for light, and thus facilitating the convergence of light. In addition, the thicknesses of each lens and the intervals between the lenses can be reasonably controlled to avoid assembly interference and reduce the assembly difficulty. Optionally, this relationship may 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 may further satisfy 20 < CT2 / AT23, so that the assembly between the lenses of the optical system 100 is simpler.

[0088] Optionally, as can be seen from the above, the projection side surface S1 of the first lens L1 is attached with a polarized reflection structure and a first phase retarder. Based on this, in order to facilitate attachment, the projection side surface S1 of the first lens L1 is a flat curved surface, and the curvature radius R1 of the projection side surface S1 of the first lens L1 at the optical axis satisfies: |R1|>80mm. That is, the projection side surface S1 of the first lens L1 is relatively flat, which is conducive to the attachment of the polarized reflection structure and the first phase retarder, reducing the difficulty of attachment.

[0089] In some embodiments, the optical system 100 satisfies the following relationship: |R1| / R2<-2. Wherein, 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, the ratio of the radius of curvature of the projection side surface S1 of the first lens L1 to the image source side surface S2 of the first lens L1 at the optical axis can be effectively controlled, thereby effectively controlling the surface shapes of the projection side surface S1 and the image source side surface S2 of the first lens L1, thereby facilitating the reduction of the reflection of light between two adjacent lenses, thereby reducing the ghost image intensity of the optical system 100. Optionally, the relationship can further satisfy |R1| / R2<-3, which is further conducive to reducing the ghost image intensity of the optical system 100.

[0090] In some embodiments, the optical system 100 satisfies the following relationship: |R4| / R3<-1. Wherein, 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 radius of curvature of the projection side surface S3 of the second lens L2 to the image source side surface S4 of the second lens L2 at the optical axis can be effectively controlled, thereby effectively controlling the surface shapes of the projection side surface S3 and the image source side surface S4 of the second lens L2, which is beneficial to reduce the reflection of light between two adjacent lenses, thereby reducing the ghost image intensity of the optical system 100. Optionally, the relationship can further satisfy |R4| / R3<-1.3, which is further beneficial 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 of the third lens L3 to the radius of curvature of the image-source-side surface S6 of the third lens L3 at the optical axis can be effectively controlled, thereby effectively controlling the surface shapes 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] Embodiment 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 plane IMG, which are sequentially arranged along the optical axis from the projection side to the image source side.

[0095] The projection-side surface S1 of the first lens L1 is provided with a polarization reflection structure (not shown), a first phase retardation plate (not shown), and a beam splitting 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 to ensure 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 1It can be seen that in the first embodiment, when the optical system 100 is in a short focus state, the distance between the first lens L1 and the second lens L2 is the smallest, that is, at this time, the first lens L1 is closest to the second lens L2. When the optical system 100 is in a medium focus state, the first lens L1 gradually moves away from the second lens L2 until the optical system 100 is in a long focus state, at which time, the distance between the first lens L1 and the second lens L2 is the largest, that is, at this time, the first lens L1 is farthest from the second lens L2.

[0099] The parameters of the optical system 100 are given in the following Table 1. The components along the optical axis of the optical system 100 from the projection side to the image source side are arranged in the order of the components 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 from the image source surface to the next surface of the lens on the optical axis. Among the parameters shown 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 from the projection side surface S1 of the first lens L1 to the image source surface of the optical system on the optical axis. Except for the unit of FOV in Table 1, the units of other parameters are mm. Since the first lens L1 is movable on the optical axis, Table 2 shows the values ​​of A and C in Table 1 in the short focus state, the medium focus state, and the long focus state. Among them, A refers to the distance between the image source side surface S2 of the first lens L1 and the projection side surface S3 of the second lens L2 on the optical axis, and C refers to the virtual image distance. In addition, Table 2 also shows the focal length ft1 of the optical system 100 in the short focus state, the focal length ft3 in the medium focus state, and the focal length ft2 in the long focus state. It can be understood that the units of the parameters in Table 2 are all mm.

[0100] In addition, each surface of the first lens L1 to the third lens L3 may be an aspherical surface, wherein the surface shape x of the aspherical lens may be defined by but not limited to the following aspherical surface formula:

[0101]

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

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

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

[0105] Table 1

[0106]

[0107]

[0108] Table 2

[0109] parameter Short focus state Mid-focus state Telephoto state 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 Aberration and distortion curves of the optical system 100 are shown. Figure 2 (A) in FIG. 1 shows the astigmatism curves at wavelengths of 456 nm, 531 nm, and 640 nm. The horizontal axis along the X-axis represents the focus offset, and the vertical axis along the Y-axis represents the image height, in units of mm. The field curvature curve represents the meridional imaging surface curvature and the sagittal imaging surface curvature. It can be seen from the figure that the field curvature of the optical system 100 is small, the field curvature and astigmatism of each field of view are well corrected, and the center and edge of the field of view have clear imaging.

[0113] See also Figure 2 In (B), Figure 2 (B) is a distortion curve diagram of the optical system 100 of this embodiment at wavelengths of 456nm, 531nm, and 640nm. The horizontal axis along the X-axis direction represents the distortion, and the vertical axis along the Y-axis direction represents the image height, in units of mm. Figure 2 As can be seen from (B) in FIG. 1 , at a wavelength of 623 nm, the distortion of the optical system 100 is well corrected.

[0114] See also Figure 3 , Figure 3The spherical aberration curves of the optical system 100 at wavelengths of 456 nm, 531 nm, and 640 nm are shown. In the figure, the horizontal axis along the X-axis direction represents the focus offset, and the vertical axis along the Y-axis direction 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, which means that the imaging quality of the optical system 100 in this embodiment is better.

[0115] Embodiment 2

[0116] The structural schematic diagram of the optical system 100 disclosed in the second embodiment of the present application is as follows: Figure 4 As shown, the optical system 100 includes a stop STO (i.e., the pupil of the 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, which are arranged in sequence along the optical axis from the projection side to the image source side.

[0117] In the second embodiment, Figure 4 (a) is a schematic diagram of the optical system in a short-focus state. Figure 4 (b) is a schematic diagram of the optical system in the mid-focus state. Figure 4 (c) in the figure is a schematic diagram of the optical system in the telephoto state. Figure 4 It can be seen from the figure that when the optical system 100 is in a short focus state, the distance between the first lens L1 and the second lens L2 is the smallest, that is, at this time, the first lens L1 is closest to the second lens L2. When the optical system 100 is in a medium focus state, the first lens L1 gradually moves away from the second lens L2 until the optical system 100 is in a long focus state, at which time, the distance between the first lens L1 and the second lens L2 is the largest, that is, at this time, the first lens L1 is farthest from the second lens L2.

[0118] The refractive powers of the first lens L1 to the third lens L3 are the same as those of the first embodiment. 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 at the near optical axis, the designs of other lens surfaces are the same as those of the first embodiment.

[0119] As shown in Table 4 below, the definitions of the parameters in Table 4 can be obtained by referring to the description of Table 1 in Example 1, and will not be repeated here. It can be understood that the units of the radius of curvature, thickness, and focal length in Table 4 are all mm. For the interpretation of Table 5 and Table 6, please refer to the description of Table 2 and Table 3 in Example 1, and will not be repeated here.

[0120] Table 4

[0121]

[0122] Table 5

[0123]

[0124]

[0125] Table 6

[0126]

[0127] See also Figure 5 , Figure 5 Aberration and distortion curves of the optical system 100 are shown. Figure 5 (A) Figure 5 The wavelengths corresponding to the curves in (B) can be referred to in Example 1. Figure 2 (A) Figure 2 The contents described in (B) will not be repeated here.

[0128] See also Figure 6 , Figure 6 The vertical axis chromatic aberration curve of the optical system is shown. Figure 6 It can be seen from the figure 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. Figure 6 The wavelengths corresponding to the curves in the embodiment 1 can be referred to Figure 3 The above is not repeated here.

[0129] Embodiment 3

[0130] The structural schematic diagram of the optical system 100 disclosed in the third embodiment of the present application is as follows: Figure 7 As shown, the optical system 100 includes a stop STO (i.e., the pupil of the 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, which are arranged in sequence along the optical axis from the projection side to the image source side.

[0131] from Figure 7 It can be seen that Figure 7 (a) is a schematic diagram of the optical system in a short-focus state. Figure 7 (b) is a schematic diagram of the optical system in the mid-focus state. Figure 7 (c) in the figure is a schematic diagram of the optical system in the telephoto state. Figure 7It can be seen that in the first embodiment, when the optical system 100 is in a short focus state, the distance between the first lens L1 and the second lens L2 is the smallest, that is, at this time, the first lens L1 is closest to the second lens L2. When the optical system 100 is in a medium focus state, the first lens L1 gradually moves away from the second lens L2 until the optical system 100 is in a long focus state, at which time, the distance between the first lens L1 and the second lens L2 is the largest, that is, at this time, the first lens L1 is farthest from the second lens L2.

[0132] The first lens L1 has positive refractive power, and the second lens L2 and the third lens L3 all 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 at the near optical axis, the surface shapes of the other lenses are the same as those in the first embodiment, and will not be repeated here.

[0133] As shown in Table 7 below, the definitions of the parameters in Table 7 can be obtained by referring to the description of Table 1 in Example 1, and will not be repeated here. It can be understood that the units of the 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 description 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 focus state Mid-focus state Telephoto state 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] See also Figure 8 , Figure 8 Aberration and distortion curves of the optical system 100 are shown. Figure 8 (A) Figure 8 The wavelengths corresponding to the curves in (B) can be referred to in Example 1. Figure 2 (A) Figure 2 The contents described in (B) will not be repeated here.

[0142] See also Fig. 9 , Fig. 9 The vertical axis chromatic aberration curve of the optical system is shown. Fig. 9 It can be seen from the figure 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. Fig. 9The wavelengths corresponding to the curves in the embodiment 1 can be referred to Figure 3 The above is not repeated here.

[0143] Embodiment 4

[0144] The structural schematic diagram of the optical system 100 disclosed in the fourth embodiment of the present application is as follows: Fig.10 As shown, the optical system 100 includes a stop STO (i.e., the pupil of the 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, which are arranged in sequence along the optical axis from the projection side to the image source side.

[0145] from Fig.10 It can be seen that Fig.10 (a) is a schematic diagram of the optical system in a short-focus state. Fig.10 (b) is a schematic diagram of the optical system in the mid-focus state. Fig.10 (c) in the figure is a schematic diagram of the optical system in the telephoto state. Fig.10 It can be seen that in the first embodiment, when the optical system 100 is in the short focus state, the distance between the first lens L1 and the second lens L2 is the largest, that is, at this time, the first lens L1 is farthest from the second lens L2. When the optical system 100 is in the medium focus state, the first lens L1 gradually approaches the second lens L2 until the optical system 100 is in the long focus state, at which time, the distance between the first lens L1 and the second lens L2 is the smallest, that is, at this time, the first lens L1 is closest to the second lens L2.

[0146] In this embodiment, the refractive powers of the first lens L1 to the third lens L3 are the same as those in the first embodiment. 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 a concave surface, and the image source side surface S4 of the second lens L2 is a convex surface at the near optical axis, the surface shapes of other lenses are the same as those in the first embodiment, and will not be repeated here.

[0147] As shown in Table 10 below, the definitions of the parameters in Table 10 can be obtained by referring to the description of Table 1 in Example 1, and will not be repeated here. It can be understood that the units of the 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 description of Tables 2 and 3 in Example 1, and will not be repeated here.

[0148] Table 10

[0149]

[0150] Table 11

[0151] parameter Short focus state Mid-focus state Telephoto state 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] See also Fig.11 , Fig.11 Aberration and distortion curves of the optical system 100 are shown. Fig.11 (A) Fig.11 The wavelengths corresponding to the curves in (B) can be referred to in Example 1. Figure 2 (A) Figure 2 The contents described in (B) will not be repeated here.

[0155] See also Fig.12 , Fig.12 The vertical axis chromatic aberration curve of the optical system is shown. Fig.12 It can be seen from the figure 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. Fig.12 The wavelengths corresponding to the curves in the embodiment 1 can be referred to Figure 3 The above is not repeated here.

[0156] Embodiment 5

[0157] The structural schematic diagram of the optical system 100 disclosed in the fifth embodiment of the present application is as follows: Fig.13 As shown, the optical system 100 includes a stop STO (i.e., the pupil of the 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, which are arranged in sequence along the optical axis from the projection side to the image source side.

[0158] The refractive powers of the first lens L1 to the third lens L3 may be referred to in Example 1 and will not be described in detail herein.

[0159] In the fifth embodiment, the surface designs of the first lens L1 to the third lens L3 are the same as those in the first embodiment, except that the image source side surface S4 of the second lens L2 is convex at the near optical axis, and the surface designs of the other lens surfaces are the same as those in the first embodiment, which will not be described again.

[0160] from Fig.13 It can be seen that Fig.13 (a) is a schematic diagram of the optical system in a short-focus state. Fig.13 (b) is a schematic diagram of the optical system in the mid-focus state. Fig.13 (c) in the figure is a schematic diagram of the optical system in the telephoto state. Fig.13It can be seen that in the first embodiment, when the optical system 100 is in the short focus state, the distance between the first lens L1 and the second lens L2 is the largest, that is, at this time, the first lens L1 is farthest from the second lens L2. When the optical system 100 is in the medium focus state, the first lens L1 gradually approaches the second lens L2 until the optical system 100 is in the long focus state, at which time, the distance between the first lens L1 and the second lens L2 is the smallest, that is, at this time, the first lens L1 is closest to the second lens L2.

[0161] In this embodiment, the refractive powers of the first lens L1 to the third lens L3 are the same as those in the first embodiment. 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 a concave surface, and the image source side surface S4 of the second lens L2 is a convex surface at the near optical axis, the surface shapes of other lenses are the same as those in the first embodiment, and will not be repeated here.

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

[0163] Table 13

[0164]

[0165]

[0166] Table 14

[0167] parameter Short focus state Mid-focus state Telephoto state 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] See also Fig.14 , Fig.14 Aberration and distortion curves of the optical system 100 are shown. Fig.14 (A) Fig.14 The wavelengths corresponding to the curves in (B) can be referred to in Example 1. Figure 2 (A) Figure 2 The contents described in (B) will not be repeated here.

[0171] See also Fig.15 , Fig.15 The vertical axis chromatic aberration curve of the optical system is shown. Fig.15It can be seen from the figure 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. Fig.15 The wavelengths corresponding to the curves in the embodiment 1 can be referred to Figure 3 The above is not repeated here.

[0172] Please refer to Table 16, which is a summary of the ratios of the various relationship equations in Examples 1 to 6 of the present application.

[0173] Table 16

[0174]

[0175]

[0176] Second, see Fig.16 The present application also discloses a head-mounted device, the head-mounted device 200 includes a housing 201, a display (not shown), and the optical system 100 as described in the first aspect above, the display and the optical system 100 are arranged 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 arranged in the housing 201, it can be arranged in the housing 201. Optionally, the head-mounted device 200 may include but is not limited to AR glasses, AR helmets, etc.

[0177] An optical system and a head-mounted device disclosed in an embodiment of the present application are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the optical system and the head-mounted device of the present application and their core ideas. At the same time, for those skilled in the art, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. An optical system, characterized in that: There are three lenses with refractive power. The optical system includes the following in order from the projection side to the image source side along the optical axis: A first lens has positive refractive power, an image source side surface of the first lens is convex near the optical axis, and the first lens is movable along the optical axis; A second lens having refractive power, wherein a projection side surface of the second lens is concave at a near optical axis; A third lens has positive refractive power, and a projection side surface and an image source side surface of the third lens are both convex surfaces at the near 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 delay plate and a beam splitter are sequentially provided on the surface from the projection side to the image source side along the optical axis. The first phase delay plate and the beam splitter are respectively located on the projection side and the image source side of the first lens.

2. The optical system according to claim 1, characterized in that The diopter 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, the first protective glass is 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: 1.2<TTL / ft2<1.7; Wherein, TTL is the distance from the projection side surface of the first protective glass to the image source surface of the optical system on the optical axis, and ft2 is the focal length of the optical system in a telephoto state.

4. The optical system according to claim 1, characterized in that The optical system satisfies the following relationship: 0.65<IH / ft<1.1, and / or, 1.1<D11 / IH<1.8; Wherein, IH is the image height corresponding to half of the maximum field angle of the optical system, ft2 is the focal length of the optical system in a telephoto state, and D11 is the maximum effective semi-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: 4<f1 / ft2<11, and / or, 5<|f2| / ft2, and / or, 1.6<f3 / ft2<3.2, and / or, 0.9<ft2 / ft1<1.2; Among them, 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 a telephoto state, and ft1 is the focal length of the optical system in a short focal 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 a curvature radius 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 relationship: |R1| / R2<-2, and / or, |R4| / R3<-1, and / or, 4<R5 / R6; Among them, R1 is the curvature radius of the projection side surface of the first lens at the optical axis, R2 is the curvature radius of the image source side surface of the first lens at the optical axis; R4 is the curvature radius of the image source side surface of the second lens at the optical axis, R3 is the curvature radius of the projection side surface of the second lens at the optical axis, R5 is the curvature radius of the projection side surface of the third lens at the optical axis, and R6 is the curvature radius 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: 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; Among them, 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 from the image source side surface of the second lens to the projection side surface of the third lens on the optical axis, and AT12 is the distance from the image source side surface of the first lens to the projection side surface of the second lens on the optical axis.

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 angle of the optical system.

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

Images