Optical system and virtual reality device
By using a two-lens design and optical path deflection technology, the problems of thinness and large zoom range in the optical system of virtual reality devices have been solved, improving imaging quality and applicability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANCHANG OFILM HUAGUANG TECH CO LTD
- Filing Date
- 2023-04-21
- Publication Date
- 2026-05-15
AI Technical Summary
The optical systems of existing virtual reality devices struggle to achieve a large zoom range while remaining thin and light, resulting in large device sizes that cannot be adapted to users with different visual acuity.
It employs a two-lens design with refractive power, where the image source and imaging surfaces are convex and concave structures, respectively. The optical path is deflected and folded using a polarizing reflective film, a phase retardation film, and a beam splitter. Zooming is achieved by moving the lenses, meeting the 86deg requirement.
It achieves a thinner and lighter optical system with a larger zoom range, improving image quality and applicability to meet the needs of different vision levels.
Smart Images
Figure CN116626896B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of optical imaging, and particularly relates to an optical system and a virtual reality device. Background Art
[0002] With the development of virtual reality technology, the types of virtual reality devices are diversified and the application fields are becoming more and more extensive. In order to make virtual reality devices suitable for users with different visual acuities, it is necessary to increase the zoom range of the optical system and enable the optical system to achieve clear imaging within this zoom range. On this basis, how to further shorten the total length of the optical system and realize the thin and light of the virtual reality device has become a problem that needs to be solved in the industry at present. Summary of the Invention
[0003] The purpose of the present invention is to provide an optical system and a virtual reality device to solve the requirements of the optical system for a large zoom range and thinness.
[0004] To achieve the purpose of the present invention, the following technical solutions are provided:
[0005] In the first aspect, the present invention provides an optical system, which has a total of two lenses with refractive power, and sequentially includes from the image source side to the imaging side along the optical axis: a first lens with positive refractive power, the image source surface of the first lens is convex near the optical axis, and the imaging surface of the first lens is concave near the optical axis; a second lens with positive refractive power, the image source surface of the second lens is convex near the optical axis, and the imaging surface of the second lens is concave near the optical axis; a beam splitting film is provided on the image source surface of the first lens, a polarization reflector is provided on the image source surface of the second lens, a phase retardation film is provided on the imaging surface of the first lens or the image source surface of the polarization reflector, the second lens is fixed relative to the light source surface, and the first lens moves along the optical axis to enable the optical system to zoom between the telephoto state and the close-focus state.
[0006] The optical system satisfies the relationship: 86deg < FOV < 94deg; where FOV is the maximum field angle of the optical system.
[0007] The light source surface of the optical system is located on the image source side of the first lens and is used to provide imaging light. The light emitted by the light source surface is the first circularly polarized light. The first circularly polarized light passes through the beam splitter film, then passes through the first lens, and then passes through the phase retarder, changing from the first circularly polarized light to the first linearly polarized light. The first linearly polarized light is reflected by the polarization reflector and passes through the phase retarder again, changing from the first linearly polarized light to the first circularly polarized light. The first circularly polarized light is reflected at the beam splitter film after passing through the first lens, changing from the first circularly polarized light to the second circularly polarized light. The polarization direction of the second circularly polarized light is opposite to the chirality of the first circularly polarized light. After the second circularly polarized light passes through the first lens, it passes through the phase retarder, changing from the second circularly polarized light to the second linearly polarized light. The second linearly polarized light passes through the polarization reflector and reaches the human eye after passing through the second lens. By setting the polarization reflector film, the phase retarder, and the beam splitter film, the light emitted by the light source surface undergoes multiple phase retardations, transmissions, and reflections, realizing the deflection and folding of the optical path, increasing the optical path of the light in the optical system. Since there is a mutual compensation relationship between the two lenses, the requirement for the deflection angle of each lens for the imaging light is reduced, making the thickness of the lens smaller, which is beneficial to meeting the requirement of being thin and light. By moving the first lens along the optical axis, the focal length of the optical system can be changed to make the optical system meet the requirement of a large zoom range.
[0008] By making the first lens have a positive refractive power, and the image source surface of the first lens is convex near the optical axis, and the imaging surface of the first lens is concave near the optical axis, it is beneficial to shorten the overall optical length of the optical system, compress the light path of each field of view, reduce spherical aberration, and meet the requirement of the optical system being thin and light. By making the image source surface of the first lens convex near the optical axis, it is beneficial to enhance the positive refractive power of the first lens and further provide a reasonable light incident angle for the introduction of marginal rays; By making the second lens have a positive refractive power, and the image source surface of the second lens is convex near the optical axis, and the imaging surface of the second lens is concave near the optical axis, it is beneficial to further shorten the overall optical length of the optical system, reduce the sensitivity to tolerances, and at the same time, it is also beneficial to correct distortion, astigmatism, and field curvature, thereby meeting the requirement of the optical system being thin and light.
[0009] By making the optical system satisfy 86deg < FOV < 94deg, it is beneficial to control the maximum field of view angle of the optical system within a reasonable range, making the optical system have an appropriate field of view angle, and can also effectively control distortion and improve imaging quality. Below the lower limit of the relationship, the field of view angle of the optical system is too small and the practicability is poor; exceeding the upper limit of the relationship, the off-axis field distortion of the optical system is large, resulting in poor imaging quality at the edge of the optical system.
[0010] In one embodiment, the optical system satisfies the relationship: 0.5 < TTL / IH < 1.5; where TTL is the distance from the imaging surface of the second lens to the light source surface of the optical system on the optical axis, and IH is half of the diagonal length of the largest effective light source area on the light source surface of the optical system. By making the optical system satisfy the above relationship, it is beneficial to control the ratio of the total optical length of the optical system to half of the diagonal length of the largest effective light source area on the light source surface of the optical system within a reasonable range, ensuring that the optical system has good thin and light characteristics and a relatively well-matched image plane size. Below the lower limit of the relationship, the total length of the optical system is too small, and the convergence of aberrations is poor, which is not conducive to improving the imaging quality of the optical system; exceeding the upper limit of the relationship, the total length of the optical system is too large, making it difficult to meet the requirements of thin and light design.
[0011] In one embodiment, the optical system satisfies the relationship: 0.2 < IH / (2*EFLS) < 0.65; where IH is half of the diagonal length of the largest effective light source area on the light source surface of the optical system, and EFLS is the focal length of the optical system in the near-focus state. By making the optical system satisfy the above relationship, it is beneficial to control the ratio of the image height corresponding to the maximum field angle of the optical system to the focal length of the optical system in the near-focus state within a reasonable range, ensuring that the optical system achieves a high imaging quality in the near-focus state. Below the lower limit of the relationship, the convergence of aberrations is poor, which is not conducive to improving the imaging quality of the optical system; exceeding the upper limit of the relationship, it is difficult to meet the requirements of thin and light design.
[0012] In one embodiment, the optical system satisfies the relationship: 0.3 < IH / (2*EFLL) < 0.4; where IH is half of the diagonal length of the largest effective light source area on the light source surface of the optical system, and EFLL is the focal length of the optical system in the far-focus state. By making the optical system satisfy the above relationship, it is beneficial to control the ratio of the image height corresponding to the maximum field angle of the optical system to the focal length of the optical system in the far-focus state within a reasonable range, ensuring that the optical system achieves a high imaging quality in the far-focus state. Below the lower limit of the relationship, the convergence of aberrations is poor, which is not conducive to improving the imaging quality of the optical system; exceeding the upper limit of the relationship, it is difficult to meet the requirements of thin and light design.
[0013] In one embodiment, the optical system satisfies the relationship: 0.9<Dmax / (2*IH)<1.1; where Dmax is the maximum effective aperture of the image source surface of the first lens, and IH is half of the diagonal length of the largest effective light source area on the light source surface of the optical system. By making the optical system satisfy the above relationship, it is beneficial to control the ratio of the maximum effective aperture of the lens in the optical system to the image height corresponding to the maximum field angle within a reasonable range, ensure that the effective apertures of each lens in the optical system are maintained within a reasonable range, make the aperture sizes of each lens appropriate, improve the compactness of the optical system structure, and meet the requirements of miniaturization.
[0014] In one embodiment, the optical system satisfies the relationship: 0.8<(AG12S - AG12L) / (EFLL - EFLS)<1.3; where AG12S is the distance on the optical axis from the imaging surface of the first lens to the image source surface of the second lens when the optical system is in the near-focus state, AG12L is the distance on the optical axis from the imaging surface of the first lens to the image source surface of the second lens when the optical system is in the far-focus state, EFLL is the focal length of the optical system when it is in the far-focus state, and EFLS is the focal length of the optical system when it is in the near-focus state. By making the optical system satisfy the above relationship, it is beneficial to constrain the lens gap between the first lens and the second lens, use the gap to reduce the aberration and tolerance sensitivity of the optical system during the zoom process, and also make the arrangement of the non-optical effective diameter regions of the lenses appropriate, improve the processability, and increase the feasibility of mass production.
[0015] In one embodiment, the optical system satisfies the relationship: 1.2<L2S2R / L2S1R<1.5; where L2S2R is the radius of curvature of the imaging surface of the second lens on the optical axis, and L2S1R is the radius of curvature of the image source surface of the second lens on the optical axis. By making the optical system satisfy the above relationship, it is beneficial to reasonably configure the ratio of the radius of curvature of the image source surface of the second lens on the optical axis to the radius of curvature of the imaging surface of the second lens on the optical axis, thereby controlling the bending degree of the second lens, reducing the processing difficulty of the second lens. At the same time, it is also beneficial to correct the marginal aberration of the optical system, suppress the generation of astigmatism, and is beneficial to improving the imaging effect of the optical system.
[0016] In one embodiment, the optical system satisfies the relation: 1.5 < L1S2R / L1S1R < 1.7; where L1S2R is the radius of curvature of the imaging surface of the first lens on the optical axis, and L1S1R is the radius of curvature of the object source surface of the first lens on the optical axis. By making the optical system satisfy the above relation, it is beneficial to reasonably configure the ratio of the radius of curvature of the object source surface of the first lens on the optical axis to the radius of curvature of the imaging surface of the first lens on the optical axis, thereby controlling the bending degree of the first lens, reducing the processing difficulty of the first lens. At the same time, it is also beneficial to correct the marginal aberration of the optical system, suppress the generation of astigmatism, and improve the imaging effect of the optical system.
[0017] In one embodiment, the optical system satisfies the relation: 0 < |(L2S1D / (2*L2S1R)| < 0.7; where L2S1D is the maximum effective aperture of the object source surface of the second lens, and L2S1R is the radius of curvature of the object source surface of the second lens on the optical axis. By making the optical system satisfy the above relation, it is beneficial to reasonably configure the ratio of the effective aperture of the object source surface of the second lens to the radius of curvature of the object source surface of the second lens on the optical axis, thereby preventing the surface shape of the object source surface of the second lens from being overly bent, reducing the processing difficulty of the second lens. It is also beneficial to set the polarization reflector on the object source surface of the second lens; at the same time, it also prevents the object source surface of the second lens from being too flat, thereby effectively balancing the chromatic aberration between the center and the periphery and suppressing excessive or insufficient chromatic aberration.
[0018] In one embodiment, the optical system satisfies the relation: 0.8 < CT2 / CT1 < 0.9; where CT1 is the thickness of the first lens on the optical axis, and CT2 is the thickness of the second lens on the optical axis. By making the optical system satisfy the above relation, it is beneficial to reasonably configure the ratio of the thickness of the second lens on the optical axis to the thickness of the first lens on the optical axis, reasonably control the center thicknesses of the first lens and the second lens, and effectively avoid the problem of difficult processing technology caused by the first lens and the second lens being too thin. It is also beneficial to reduce the size of the optical system and keep its miniaturized characteristics.
[0019] In a second aspect, the present invention also provides a virtual reality device, which includes a housing and the optical system according to any one of the embodiments in the first aspect, and the optical system is housed in the housing. By adding the optical system provided by the present invention to the virtual reality device, it is possible to reasonably design the surface shape and refractive power of each lens in the optical system, so that the virtual reality device meets the effects of a large zoom range and being thin and light. Description of the Drawings
[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0021] Figure 1a This is a schematic diagram of the optical system in the first embodiment under near-focus conditions;
[0022] Figure 1b It shows Figure 1a Astigmatism curve and distortion curve;
[0023] Figure 1c This is a schematic diagram of the optical system in the first embodiment under the mid-focus state;
[0024] Figure 1d It shows Figure 1c Astigmatism curve and distortion curve;
[0025] Figure 1e This is a schematic diagram of the optical system in the first embodiment in the telephoto state;
[0026] Figure 1f It shows Figure 1e Astigmatism curve and distortion curve;
[0027] Figure 2a This is a schematic diagram of the optical system in the near-focus state according to the second embodiment;
[0028] Figure 2b It shows Figure 2a Astigmatism curve and distortion curve;
[0029] Figure 2c This is a schematic diagram of the optical system in the second embodiment under the mid-focus state;
[0030] Figure 2d It shows Figure 2c Astigmatism curve and distortion curve;
[0031] Figure 2e This is a schematic diagram of the optical system in the telephoto state according to the second embodiment;
[0032] Figure 2f It shows Figure 2e Astigmatism curve and distortion curve;
[0033] Figure 3a This is a schematic diagram of the optical system in the third embodiment under near-focus conditions;
[0034] Figure 3b It shows Figure 3a Astigmatism curves and distortion curves;
[0035] Figure 3c This is a schematic diagram of the optical system in the middle focal state according to the third embodiment;
[0036] Figure 3d It shows Figure 3c Astigmatism curve and distortion curve;
[0037] Figure 3e This is a schematic diagram of the optical system in the third embodiment in the telephoto state;
[0038] Figure 3f It shows Figure 3e Astigmatism curve and distortion curve;
[0039] Figure 4a This is a schematic diagram of the optical system in the fourth embodiment under near-focus conditions;
[0040] Figure 4b It shows Figure 4a Astigmatism curve and distortion curve;
[0041] Figure 4c This is a schematic diagram of the optical system in the middle focal state according to the fourth embodiment;
[0042] Figure 4d It shows Figure 4c Astigmatism curve and distortion curve;
[0043] Figure 4e This is a schematic diagram of the optical system in the fourth embodiment in the telephoto state;
[0044] Figure 4f It shows Figure 4e Astigmatism curve and distortion curve;
[0045] Figure 5 A schematic diagram of the structure of a virtual reality device according to one embodiment of the present invention is shown. Detailed Implementation
[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0047] In a first aspect, the present invention provides an optical system, which includes two lenses with refractive power. Along the optical axis, from the image source side to the imaging side, it successively includes: a first lens with positive refractive power. The image source surface of the first lens is convex near the optical axis, and the imaging surface of the first lens is concave near the optical axis; a second lens with positive refractive power. The image source surface of the second lens is convex near the optical axis, and the imaging surface of the second lens is concave near the optical axis; the second lens is fixed relative to the light source surface, and the first lens moves along the optical axis to enable the optical system to zoom between a telephoto state and a close-focus state.
[0048] The optical system satisfies the relation: 86deg < FOV < 94deg; where FOV is the maximum field angle of the optical system. Specifically, the value of FOV can be 90, 92, 88, 86, 91, 87, 89, 93, etc., with the unit of deg.
[0049] The light source surface of the optical system is located on the image source side of the first lens and is used to provide imaging light. The light emitted from the light source surface is first circularly polarized light. The first circularly polarized light passes through a beam splitter film, then passes through the first lens, and then passes through a phase retardation plate, changing from the first circularly polarized light to the first linearly polarized light. The first linearly polarized light is reflected by a polarization reflector, passes through the phase retardation plate again, and changes from the first linearly polarized light to the first circularly polarized light. The first circularly polarized light is reflected at the beam splitter film after passing through the first lens, changing from the first circularly polarized light to the second circularly polarized light. The polarization direction of the second circularly polarized light is opposite to the helicity of the first circularly polarized light. After passing through the first lens, the second circularly polarized light passes through the phase retardation plate and changes from the second circularly polarized light to the second linearly polarized light. The second linearly polarized light passes through the polarization reflector and reaches the human eye after passing through the second lens. By setting the polarization reflector film, the phase retardation plate, and the beam splitter film, the light emitted from the light source surface undergoes multiple phase retardations, transmissions, and reflections, realizing the deflection and folding of the optical path, increasing the optical path of the light in the optical system. Since there is a mutual compensation relationship between the two lenses, the requirement for the deflection angle of each lens for the imaging light is reduced, making the thickness of the lens smaller, which is beneficial to meeting the requirement of being thin and light. By moving the first lens along the optical axis, the focal length of the optical system can be changed to enable the optical system to meet the requirement of a large zoom range.
[0050] It should be noted that the above exemplary description is only for principle illustration and does not limit the position settings of the polarization reflection sheet 12, the phase retardation sheet 13, and the beam splitting film 11. For example, the polarization reflection sheet 12 can be disposed on the image source surface S7 of the second lens L2, the phase retardation sheet 13 can be disposed on the imaging surface S4 of the first lens L1, and the beam splitting film 11 can be disposed on the image source surface S3 of the first lens L1; or, the polarization reflection sheet 12 and the phase retardation sheet 13 can be sequentially disposed on the image source surface S7 of the second lens L2, that is, the phase retardation sheet 13 is disposed on the image source surface of the polarization reflection sheet 12. This is not an exhaustive list here, as long as the three are arranged in sequence from the imaging side to the image source side, and the phase retardation sheet 13 is not limited to a quarter-wave plate, and other phase retardation structures such as a half-wave plate can also be selected.
[0051] By making the first lens have a positive refractive power, and the image source surface of the first lens is convex near the optical axis, and the imaging surface of the first lens is concave near the optical axis, it is beneficial to shorten the total optical length of the optical system, compress the light path of each field of view, reduce spherical aberration, and meet the requirements of the optical system for being thin and light. By making the image source surface of the first lens be convex near the optical axis, it is beneficial to enhance the positive refractive power of the first lens and further provide a reasonable light incident angle for the introduction of marginal rays; by making the second lens have a positive refractive power, and the image source surface of the second lens is convex near the optical axis, and the imaging surface of the second lens is concave near the optical axis, it is beneficial to further shorten the total optical length of the optical system, reduce the tolerance sensitivity, and at the same time, it is also beneficial to correct distortion, astigmatism, and field curvature, so as to meet the requirements of the optical system for being thin and light.
[0052] By making the optical system satisfy 86deg < FOV < 94deg, it is beneficial to control the maximum field of view angle of the optical system within a reasonable range, make the optical system have a suitable field of view angle, and effectively control distortion and improve imaging quality. Below the lower limit of the relational expression, the field of view angle of the optical system is too small and the practicability is poor; exceeding the upper limit of the relational expression, the off-axis field distortion of the optical system is large, resulting in poor imaging quality at the edge of the optical system.
[0053] In one implementation, the optical system satisfies the relational expression: 0.5 < TTL / IH < 1.5; where, TTL is the distance from the image source surface of the first lens to the imaging surface of the optical system on the optical axis, and IH is half of the diagonal length of the largest effective light source area on the light source surface of the optical system. Specifically, the value of TTL / IH can be 0.976, 0.978, 0.979, 0.563, 0.731, 1.483, 1.223, 0.858, etc.
[0054] By making the optical system satisfy the above relationship, it is beneficial to control the ratio of the total optical length of the optical system to the image height corresponding to the maximum field angle within a reasonable range, ensuring that the optical system has good thin and light characteristics and a relatively well-matched image plane size. Below the lower limit of the relationship, the total length of the optical system is too small, and the convergence of aberrations is poor, which is not conducive to improving the imaging quality of the optical system; exceeding the upper limit of the relationship, the total length of the optical system is too large, making it difficult to meet the requirements of thin and light design.
[0055] In one embodiment, the optical system satisfies the relationship: 0.2 < IH / (2*EFLS) < 0.65; where IH is half of the diagonal length of the largest effective light source area on the light source surface of the optical system, and EFLS is the focal length of the optical system in the near-focus state. Specifically, the value of IH / (2*EFLS) can be 0.397, 0.392, 0.400, 0.384, 0.246, 0.641, 0.519, 0.297, etc.
[0056] By making the optical system satisfy the above relationship, it is beneficial to control the ratio of the image height corresponding to the maximum field angle of the optical system to the focal length of the optical system in the near-focus state within a reasonable range, ensuring that the optical system achieves high imaging quality in the near-focus state. Below the lower limit of the relationship, the convergence of aberrations is poor, which is not conducive to improving the imaging quality of the optical system; exceeding the upper limit of the relationship, it is difficult to meet the requirements of thin and light design.
[0057] In one embodiment, the optical system satisfies the relationship: 0.3 < IH / (2*EFLL) < 0.4; where IH is half of the diagonal length of the largest effective light source area on the light source surface of the optical system, and EFLL is the focal length of the optical system in the far-focus state. Specifically, the value of IH / (2*EFLL) can be 0.369, 0.364, 0.371, 0.356, 0.301, 0.324, 0.395, 0.382, etc.
[0058] By making the optical system satisfy the above relationship, it is beneficial to control the ratio of the image height corresponding to the maximum field angle of the optical system to the focal length of the optical system in the far-focus state within a reasonable range, ensuring that the optical system achieves high imaging quality in the far-focus state. Below the lower limit of the relationship, the convergence of aberrations is poor, which is not conducive to improving the imaging quality of the optical system; exceeding the upper limit of the relationship, it is difficult to meet the requirements of thin and light design.
[0059] In one embodiment, the optical system satisfies the relation: 0.9 < Dmax / (2*IH) < 1.1; where Dmax is the maximum effective aperture of the image source plane of the first lens, and IH is half of the diagonal length of the maximum effective light source region on the light source plane of the optical system. Specifically, the value of Dmax / (2*IH) can be 1.007, 1.030, 0.984, 1.029, 0.925, 0.939, 1.083, 0.991, etc.
[0060] By making the optical system satisfy the above relation, it is beneficial to control the ratio of the maximum effective aperture of the lens in the optical system to the image height corresponding to the maximum field angle within a reasonable range, ensure that the effective apertures of each lens in the optical system are maintained within a reasonable range, make the aperture sizes of each lens appropriate, improve the compactness of the optical system structure, and meet the requirements of miniaturization.
[0061] In one embodiment, the optical system satisfies the relation: 0.8 < (AG12S - AG12L) / (EFLL - EFLS) < 1.3; where AG12S is the distance on the optical axis from the imaging plane of the first lens to the image source plane of the second lens when the optical system is in the near-focus state, AG12L is the distance on the optical axis from the imaging plane of the first lens to the image source plane of the second lens when the optical system is in the far-focus state, EFLL is the focal length of the optical system when it is in the far-focus state, and EFLS is the focal length of the optical system when it is in the near-focus state. Specifically, the value of (AG12S - AG12L) / (EFLL - EFLS) can be 1.028, 1.030, 0.984, 1.029, 1.274, 0.819, 1.131, 1.201, etc.
[0062] By making the optical system satisfy the above relation, it is beneficial to constrain the lens gap between the first lens and the second lens, use the gap to reduce the aberration and tolerance sensitivity of the optical system during the zooming process, and also make the arrangement of the non-optical effective diameter regions of the lenses appropriate, improve the processability, and increase the feasibility of mass production.
[0063] In one embodiment, the optical system satisfies the relation: 1.2 < L2S2R / L2S1R < 1.5; where L2S2R is the radius of curvature of the imaging plane of the second lens at the optical axis, and L2S1R is the radius of curvature of the image source plane of the second lens at the optical axis. Specifically, the value of L2S2R / L2S1R can be 1.475, 1.350, 1.411, 1.288, 1.203, 1.307, 1.405, 1.425, etc.
[0064] By making the optical system satisfy the above relationship, it is beneficial to reasonably configure the ratio of the radius of curvature of the image source surface of the second lens on the optical axis to the radius of curvature of the imaging surface of the second lens on the optical axis, thereby controlling the bending degree of the second lens and reducing the processing difficulty of the second lens. At the same time, it is also beneficial to correct the marginal aberration of the optical system, suppress the generation of astigmatism, and improve the imaging effect of the optical system.
[0065] In an embodiment, the optical system satisfies the relationship: 1.5 < L1S2R / L1S1R < 1.7; where L1S2R is the radius of curvature of the imaging surface of the first lens on the optical axis, and L1S1R is the radius of curvature of the image source surface of the first lens on the optical axis. Specifically, the value of L1S2R / L1S1R can be 1.523, 1.659, 1.660, 1.672, 1.503, 1.697, 1.601, 1.583, etc.
[0066] By making the optical system satisfy the above relationship, it is beneficial to reasonably configure the ratio of the radius of curvature of the image source surface of the first lens on the optical axis to the radius of curvature of the imaging surface of the first lens on the optical axis, thereby controlling the bending degree of the first lens and reducing the processing difficulty of the first lens. At the same time, it is also beneficial to correct the marginal aberration of the optical system, suppress the generation of astigmatism, and improve the imaging effect of the optical system.
[0067] In an embodiment, the optical system satisfies the relationship: 0 < |(L2S1D / (2*L2S1R)| < 0.7; where L2S1D is the maximum effective aperture of the image source surface of the second lens, and L2S1R is the radius of curvature of the image source surface of the second lens on the optical axis. Specifically, the value of |(L2S1D / (2*L2S1R)| can be 0.304, 0.312, 0.321, 0.303, 0.104, 0.693, 0.526, 0.261, etc.
[0068] By making the optical system satisfy the above relationship, it is beneficial to reasonably configure the ratio of the effective aperture of the image source surface of the second lens to the radius of curvature of the image source surface of the second lens on the optical axis, thereby preventing the surface shape of the image source surface of the second lens from being overly curved, reducing the processing difficulty of the second lens, and also facilitating the setting of the polarization reflector on the image source surface of the second lens; at the same time, it also prevents the image source surface of the second lens from being too flat, thereby effectively balancing the chromatic aberration between the center and the periphery and suppressing excessive or insufficient chromatic aberration.
[0069] In one embodiment, the optical system satisfies the relationship: 0.8 < CT2 / CT1 < 0.9; where CT1 is the thickness of the first lens on the optical axis, and CT2 is the thickness of the second lens on the optical axis. Specifically, the value of CT2 / CT1 can be 0.855, 0.821, 0.820, 0.824, 0.804, 0.893, 0.861, 0.872, etc.
[0070] By making the optical system satisfy the above relationship, it is beneficial to reasonably configure the ratio of the thickness of the second lens on the optical axis to the thickness of the first lens on the optical axis, reasonably control the center thicknesses of the first lens and the second lens, and thus effectively avoid the problem of difficult processing technology caused by the first lens and the second lens being too thin. It is also beneficial to reduce the size of the optical system and keep its miniaturized characteristics.
[0071] First Embodiment
[0072] Please refer to Figure 1a 、 Figure 1c and Figure 1e , the optical system 10 of this embodiment sequentially includes, from the image source side to the imaging side along the optical axis direction:
[0073] The first lens L1, having a positive refractive power, the image source surface S3 of the first lens L1 is convex near the optical axis, and the imaging surface S4 is concave near the optical axis.
[0074] The second lens L2 has positive refractive power. The image source surface S7 of the second lens L2 is convex near the optical axis, and the imaging surface S8 is concave near the optical axis. In addition, the optical system 10 also includes an aperture stop STO, a polarizing reflector 12, a phase retarder 13, a beam splitter 11, a protective glass CG, and a light source surface IM. In this embodiment, the aperture stop STO is positioned between the imaging surface of the second lens of the optical system 10 and the human eye to control the amount of light entering the lens; the polarizing reflector 12 is positioned on the image source surface S7 of the second lens L2 to transmit light at a certain angle and reflect light at another angle. Specifically, the polarizing reflector 12 reflects first linearly polarized light and transmits second linearly polarized light; the phase retarder 13 is positioned between the imaging surface S4 of the first lens L1 and the image source surface S7 of the second lens L2. Specifically, the phase retarder 13 is positioned on the image source surface S7 of the second lens L2 and is located on the image source surface of the polarizing reflector 12, including an image source surface S5 and an imaging surface S6, to change the polarization state of the light; the beam splitter 11 is positioned on the image source surface of the first lens to allow a portion of the light to pass through and a portion to be reflected; the protective glass CG is positioned on the side of the light source surface IM close to the first lens L1 to protect the light source surface IM. It can be understood that by coating the surface of the protective glass CG, the unpolarized light emitted from the light source surface IM can be converted into first circularly polarized light after passing through the protective glass CG. The protective glass CG can be part of the optical system 10 or can be removed from the optical system 10, but when the protective glass CG is removed, the total optical length of the optical system 10 remains unchanged.
[0075] Table 1a shows the parameters of the optical system 10 in this embodiment, where the Y-radius is the radius of curvature of the image source surface or imaging surface at the optical axis corresponding to the surface number. Surface numbers S3 and S4 are the image source surface S3 and imaging surface S4 of the first lens L1, respectively, and surface numbers S7 and S8 are the image source surface S7 and imaging surface S8 of the second lens L2, respectively. That is, in the same lens, the surface with the smaller surface number is the image source surface, and the surface with the larger surface number is the imaging surface. The first value in the "thickness" parameter column of the first lens L1 is the thickness of the lens on the optical axis, and the second value is the distance on the optical axis from the imaging surface of the lens to the rear surface in the imaging side direction. The focal length, material refractive index, and Abbe number are all obtained using visible light with a reference wavelength of 531 nm. The units for Y-radius, thickness, outer diameter, and focal length are all millimeters (mm). Table 1b is a supplementary table to Table 1a.
[0076] Table 1a
[0077]
[0078] Table 1b
[0079] a(mm) b(mm) c(mm) f(mm) FOV(deg) TTL(mm) Close-focus state -1500 4.117 7.883 24.2 90 18.73 Middle Jiao state -200 3.038 8.962 25.3 90 18.73 telephoto mode -125 2.266 9.734 26.0 90 18.73
[0080] Where a is the distance on the optical axis from the human eye to the aperture stop STO, b is the distance on the optical axis from the imaging surface S4 of the first lens L1 to the phase retardation plate 13, c is the distance on the optical axis from the image source surface S3 of the first lens L1 to the protective glass CG, f is the focal length of the optical system 10, FOV is the maximum field of view of the optical system 10, and TTL is the distance on the optical axis from the imaging surface S8 of the second lens L2 to the light source surface IM of the optical system, i.e., the total optical length. Moving the first lens L1 causes the focal length of the optical system to change between near-focus and far-focus states. It can be understood that when the first lens L1 moves towards the image source side, the focal length of the optical system gradually decreases until it reaches the near-focus state; when the first lens L1 moves towards the imaging side, the focal length of the optical system gradually increases until it reaches the far-focus state.
[0081] In this embodiment, the image source surface S3 and imaging surface S4 of the first lens L1, and the imaging surface S8 of the second lens L2 are all aspherical surfaces. The surface shape x of the aspherical surface can be defined using, but is not limited to, the following aspherical surface formula:
[0082]
[0083] Where x is the distance from the corresponding point on the aspherical surface to the plane tangent to the vertex of the surface, h is the distance from the corresponding point on the aspherical surface to the optical axis, c is the curvature of the vertex of the aspherical surface, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th higher-order term in the aspherical surface shape formula. Table 1c gives the higher-order coefficients A4, A6, A8, A10, and A12 of the aspherical mirrors S3, S4, and S8 that can be used in the first embodiment.
[0084] Table 1c
[0085] Face number k A4 A6 A8 A10 A12 S3 -6.2493E+00 -8.0973E-06 -3.1066E-09 2.6626E-11 2.8655E-14 -1.0869E-16 S4 1.6135E+00 7.4998E-06 -7.7057E-08 3.2517E-10 -4.7528E-13 1.4068E-16 S8 1.2367E+01 1.0367E-05 6.1197E-08 -4.0996E-10 1.3807E-12 -1.9154E-15
[0086] Figure 1b (Close-up state) Figure 1d (Middle burner state) Figure 1f (In the telephoto state) (a) shows the astigmatism curves of the optical system 10 of the first embodiment at a wavelength of 531.0000 nm, where the horizontal axis along the X-axis represents the focus shift, and the vertical axis along the Y-axis represents the image height, both in mm. The S-curve in the astigmatism curves represents the sagittal field curvature at 531.0000 nm, and the T-curve represents the meridional field curvature at 531.0000 nm. Figure 1b (Close-up state) Figure 1d (Middle burner state) Figure 1f As can be seen in (telephoto state) (a), the field curvature of the optical system 10 is small, and the field curvature and astigmatism of each field of view are well corrected, with clear imaging at the center and edge of the field of view.
[0087] Figure 1b (Close-up state) Figure 1d (Middle burner state) Figure 1f (In the telephoto state) (b) shows the distortion curves of the optical system 10 of the first embodiment at a wavelength of 531.0000 nm. The horizontal axis along the X-axis represents the distortion value, denoted as %, and the vertical axis along the Y-axis represents the image height, in mm. The distortion curves represent the distortion magnitude corresponding to different field of view angles. Figure 1b (Close-up state) Figure 1d (Middle burner state) Figure 1f As can be seen in (far-focus state) (b), at a wavelength of 531.0000nm, the image distortion caused by the main beam is small, and the imaging quality of the system is excellent.
[0088] Depend on Figure 1b (Close-up state) Figure 1d (Middle burner state) Figure 1f As can be seen in (a) and (b) of the (far-focus state), the optical system 10 of this embodiment has small aberrations, good imaging quality, and excellent imaging performance.
[0089] Second Embodiment
[0090] Please refer to Figure 2a , Figure 2c and Figure 2e The optical system 10 of this embodiment includes, sequentially from the image source side to the imaging side along the optical axis:
[0091] The first lens L1 has positive refractive power. The image source surface S3 of the first lens L1 is convex near the optical axis, and the imaging surface S4 is concave near the optical axis.
[0092] The second lens L2 has positive refractive power. The image source surface S7 of the second lens L2 is convex near the optical axis, and the imaging surface S8 is concave near the optical axis.
[0093] The other structures of the second embodiment are the same as those of the first embodiment, and can be referred to accordingly.
[0094] Table 2a shows the parameters of the optical system 10 in this embodiment. The focal length, material refractive index and Abbe number are obtained using visible light with a reference wavelength of 531 nm. The units of Y radius, thickness, outer diameter and focal length are millimeters (mm). The meanings of the other parameters are the same as those in the first embodiment. Table 2b is a supplementary table to Table 2a.
[0095] Table 2a
[0096]
[0097] Table 2b
[0098] a(mm) b(mm) c(mm) f(mm) FOV (deg) TTL(mm) Close-focus state -1500 4.330 7.670 24.5 90 18.77 Middle Jiao state -200 3.182 8.818 25.6 90 18.77 telephoto mode -125 2.373 9.627 26.4 90 18.77
[0099] Where a is the distance from the human eye to the aperture stop STO on the optical axis, b is the distance from the imaging surface S4 of the first lens L1 to the phase retardation plate 13 on the optical axis, c is the distance from the image source surface S3 of the first lens L1 to the protective glass CG on the optical axis, f is the focal length of the optical system 10, FOV is the maximum field of view of the optical system 10, and TTL is the distance from the imaging surface S8 of the second lens L2 to the light source surface IM of the optical system on the optical axis, i.e., the total optical length.
[0100] Table 2c gives the higher-order coefficients that can be used for each aspherical mirror in the second embodiment. In this embodiment, the image source surface S3 and the imaging surface S4 of the first lens L1, and the image source surface S7 and the imaging surface S8 of the second lens L2 are all aspherical. The shape of each aspherical surface can be defined by the formula given in the first embodiment.
[0101] Table 2c
[0102] Face number k A4 A6 A8 A10 A12 S3 -5.3400E+00 -6.9103E-06 4.8927E-09 2.1972E-11 -9.8249E-14 1.1339E-16 S4 2.4517E+00 8.1468E-07 1.1539E-08 -2.9416E-11 -3.5872E-14 1.2259E-16 S7 0.0000E+00 3.3303E-06 -2.7842E-08 1.8152E-10 -5.1309E-13 5.4481E-16 S8 1.4107E+00 1.1259E-05 2.9629E-09 -3.8529E-11 9.5372E-14 -9.9712E-17
[0103] Figure 2b (Close-up state) Figure 2d (Middle burner state) Figure 2f (In the telephoto state) (a) and (b) show the astigmatism curves and distortion curves of the optical system 10 at different focal lengths in the second embodiment, respectively. The astigmatism curve represents the meridional field curvature and the sagittal field curvature; the distortion curve represents the distortion magnitude corresponding to different field of view angles. Figure 2b (Close-up state) Figure 2d (Middle burner state) Figure 2f As can be seen from the aberration diagram in the (far-focus state), the field curvature and distortion of the optical system 10 are well controlled, thus the optical system 10 of this embodiment has good imaging quality.
[0104] Third Embodiment
[0105] Please refer to Figure 3a , Figure 3c and Figure 3e The optical system 10 of this embodiment includes, sequentially from the image source side to the imaging side along the optical axis:
[0106] The first lens L1 has positive refractive power. The image source surface S3 of the first lens L1 is convex near the optical axis, and the imaging surface S4 is concave near the optical axis.
[0107] The second lens L2 has positive refractive power. The image source surface S7 of the second lens L2 is convex near the optical axis, and the imaging surface S8 is concave near the optical axis.
[0108] The phase delay plate 13 of the third embodiment is disposed on the imaging surface S4 of the first lens L1. The other structures of the third embodiment are the same as those of the first embodiment and can be referred to accordingly.
[0109] Table 3a shows the parameters of the optical system 10 in this embodiment. The focal length, material refractive index and Abbe number are obtained using visible light with a reference wavelength of 531 nm. The units of Y radius, thickness, outer diameter and focal length are millimeters (mm). The meanings of the other parameters are the same as those in the first embodiment. Table 3b is a supplementary table to Table 3a.
[0110] Table 3a
[0111]
[0112] Table 3b
[0113] a(mm) b(mm) c(mm) f(mm) FOV(deg) TTL(mm) Close-focus state -1500 3.973 8.027 24.0 92 18.80 Middle Jiao state -200 2.877 9.123 25.1 92 18.80 telephoto mode -125 2.104 9.896 25.9 92 18.80
[0114] Where a is the distance from the human eye to the aperture stop STO on the optical axis, b is the distance from the phase retardation plate 13 to the image source surface S7 of the second lens L2 on the optical axis, c is the distance from the image source surface S3 of the first lens L1 to the protective glass CG on the optical axis, f is the focal length of the optical system 10, FOV is the maximum field of view of the optical system 10, and TTL is the distance from the imaging surface S8 of the second lens L2 to the light source surface IM of the optical system on the optical axis, i.e., the total optical length.
[0115] Table 3b gives the higher-order coefficients that can be used for each aspherical mirror in the third embodiment. In this embodiment, the image source surface S3 and the imaging surface S4 of the first lens L1, and the image source surface S7 and the imaging surface S8 of the second lens L2 are all aspherical. The shape of each aspherical surface can be defined by the formula given in the first embodiment.
[0116] Table 3c
[0117] Face number k A4 A6 A8 A10 A12 S3 -5.0504E+00 -6.9917E-06 6.0144E-09 2.1004E-11 -1.0419E-13 1.2214E-16 S4 2.1267E+00 -2.7229E-07 2.1529E-08 -6.3879E-11 1.0143E-14 1.0201E-16 S7 0.0000E+00 4.0570E-06 -3.1379E-08 1.9211E-10 -5.1955E-13 5.3189E-16 S8 1.3907E+00 1.2326E-05 -4.3516E-09 -1.2952E-12 -1.5089E-14 4.3796E-17
[0118] Figure 3b (Close-up state) Figure 3d (Middle burner state) Figure 3f (In the telephoto state) (a) and (b) show the astigmatism curves and distortion curves of the optical system 10 at different focal lengths in the third embodiment, respectively. The astigmatism curve represents the meridional field curvature and the sagittal field curvature; the distortion curve represents the distortion magnitude corresponding to different field of view angles. Figure 3b (Close-up state) Figure 3d (Middle burner state) Figure 3f As can be seen from the aberration diagram in the (far-focus state), the field curvature and distortion of the optical system 10 are well controlled, thus the optical system 10 of this embodiment has good imaging quality.
[0119] Fourth embodiment
[0120] Please refer to Figure 4a , Figure 4c and Figure 4e The optical system 10 of this embodiment includes, sequentially from the image source side to the imaging side along the optical axis:
[0121] The first lens L1 has positive refractive power. The image source surface S3 of the first lens L1 is convex near the optical axis, and the imaging surface S4 is concave near the optical axis.
[0122] The second lens L2 has positive refractive power. The image source surface S7 of the second lens L2 is convex near the optical axis, and the imaging surface S8 is concave near the optical axis.
[0123] In the fourth embodiment, the phase delay film 13 is disposed on the imaging surface S4 of the first lens L1. The other structures of the fourth embodiment are the same as those of the first embodiment and can be referred to accordingly.
[0124] Table 4a shows the parameters of the optical system 10 in this embodiment. The focal length, material refractive index and Abbe number are obtained using visible light with a reference wavelength of 531 nm. The units of Y radius, thickness, outer diameter and focal length are millimeters (mm). The meanings of the other parameters are the same as those in the first embodiment. Table 4b is a supplementary table to Table 4a.
[0125] Table 4a
[0126]
[0127] Table 4b
[0128] a(mm) b(mm) c(mm) f(mm) FOV(deg) TTL(mm) Close-focus state -1500 4.720 7.280 25.0 88 18.74 Middle Jiao state -200 3.513 8.487 26.1 88 18.74 telephoto mode -125 2.664 9.336 27.0 88 18.74
[0129] Where a is the distance from the human eye to the aperture stop STO on the optical axis, b is the distance from the phase retardation plate 13 to the image source surface S7 of the second lens L2 on the optical axis, c is the distance from the image source surface S3 of the first lens L1 to the protective glass CG on the optical axis, f is the focal length of the optical system 10, FOV is the maximum field of view of the optical system 10, and TTL is the distance from the imaging surface S8 of the second lens L2 to the light source surface IM of the optical system on the optical axis, i.e., the total optical length.
[0130] Table 4b gives the higher-order coefficients that can be used for each aspherical mirror in the fourth embodiment. In this embodiment, the image source surface S3 and the imaging surface S4 of the first lens L1, and the image source surface S7 and the imaging surface S8 of the second lens L2 are all aspherical. The shape of each aspherical surface can be defined by the formula given in the first embodiment.
[0131] Table 4c
[0132] Face number k A4 A6 A8 A10 A12 S3 -5.4483E+00 -6.7367E-06 4.6806E-09 2.1351E-11 -9.7191E-14 1.1527E-16 S4 2.9487E+00 6.5817E-07 1.1785E-08 -2.9687E-11 -3.5770E-14 1.2982E-16 S7 0.0000E+00 2.9762E-06 -2.7439E-08 1.8333E-10 -5.2815E-13 5.6997E-16 S8 2.9163E+00 1.1115E-05 4.6287E-09 -4.2848E-11 1.1890E-13 -1.4984E-16
[0133] Figure 4b (Near - focus state), Figure 4d (Mid - focus state), Figure 4f (Far - focus state), Figures (a) and (b) respectively show the astigmatism curve and distortion curve of the optical system 10 at different focal lengths in the fourth embodiment. Among them, the astigmatism curve represents the meridional field curvature and sagittal field curvature; the distortion curve represents the distortion magnitude values corresponding to different field angles. From Figure 4b the aberration diagram in, it can be seen that both the field curvature and distortion of the optical system 10 are well controlled, so the optical system 10 of this embodiment has good imaging quality.
[0134] Table 5 shows the values of FOV, TTL / IH, IH / (2*EFLS), IH / (2*EFLL), Dmax / (2*IH), (AG12S - AG12L) / (EFLL - EFLS), L2S2R / L2S1R, L1S2R / L1S1R, |(L2S1D / (2*L2S1R)|, CT2 / CT1 in the optical systems of the first to fourth embodiments.
[0135] Table 5
[0136] First Embodiment Second Embodiment Third Embodiment Fourth embodiment FOV 90 90 92 88 TTL / IH 0.976 0.978 0.979 0.976 IH / (2*EFLS) 0.397 0.392 0.400 0.384 IH / (2*EFLL) 0.369 0.364 0.371 0.356 Dmax / (2*IH) 1.007 1.030 1.034 1.027 (AG12S-AG12L) / (EFLL-EFLS) 1.028 1.030 0.984 1.029 L2S2R / L2S1R 1.475 1.350 1.411 1.288 L1S2R / L1S1R 1.523 1.659 1.660 1.672 |(L2S1D / (2*L2S1R)| 0.304 0.312 0.321 0.303 CT2 / CT1 0.855 0.821 0.820 0.824
[0137] As can be seen from Table 5, the optical systems of the first to fourth embodiments all satisfy the following relational expressions: 86deg < FOV < 94deg, 0.5 < TTL / IH < 1.5, 0.2 < IH / (2*EFLS) < 0.65, 0.3 < IH / (2*EFLL) < 0.4, 0.9 < Dmax / (2*IH) < 1.1, 0.8 < (AG12S - AG12L) / (EFLL - EFLS) < 1.3, 1.2 < L2S2R / L2S1R < 1.5, 1.5 < L1S2R / L1S1R < 1.7, 0 < |(L2S1D / (2*L2S1R)| < 0.7, 0.8 < CT2 / CT1 < 0.9.
[0138] Please refer to Figure 5 , the present invention also provides a virtual reality device 20, which includes a housing 21 and the optical system 10 according to any one of the embodiments of the first aspect. The optical system 10 is housed in the housing 21. By incorporating the optical system 10 provided by the present invention into the virtual reality device 20, through reasonable design of the surface shape and refractive power of each lens in the optical system 10, the virtual reality device 20 can achieve the effects of a large zoom range and being thin and light.
[0139] The above description discloses only some preferred embodiments of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art can understand that implementing all or part of the above embodiments and making equivalent changes in accordance with the claims of the present invention still fall within the scope of the present invention.
Claims
1. An optical system, characterized in that, There are two lenses with refractive power in total, which successively include from the image source side to the imaging side along the optical axis: The first lens has positive refractive power. The image source surface of the first lens is convex near the optical axis, and the imaging surface of the first lens is concave near the optical axis. The second lens has positive refractive power. The image source surface of the second lens is convex near the optical axis, and the imaging surface of the second lens is concave near the optical axis. A beam splitting film is provided on the image source surface of the first lens, a polarization reflector is provided on the image source surface of the second lens, a phase retardation film is provided on the imaging surface of the first lens or the image source surface of the polarization reflector. The second lens is fixed relative to the light source surface, and the first lens moves along the optical axis to enable the optical system to zoom between the far - focus state and the near - focus state. The optical system satisfies the relation: 86 deg < FOV < 94 deg; 0.9 < Dmax / (2*IH) < 1.1; Where, FOV is the maximum field of view angle of the optical system, Dmax is the maximum effective aperture of the image source surface of the first lens, and IH is half of the diagonal length of the largest effective light source area on the light source surface of the optical system.
2. The optical system as described in claim 1, characterized in that, The optical system satisfies the relation: 0.5 < TTL / IH < 1.5; Where, TTL is the distance from the imaging surface of the second lens to the light source surface of the optical system on the optical axis.
3. The optical system as described in claim 1, characterized in that, The optical system satisfies the relation: 0.2 < IH / (2*EFLS) < 0.65, and / or 0.3 < IH / (2*EFLL) < 0.4; Where, EFLS is the focal length of the optical system in the near - focus state, and EFLL is the focal length of the optical system in the far - focus state.
4. The optical system as claimed in claim 1, characterized in that, The optical system satisfies the relation: 0.8 < (AG12S - AG12L) / (EFLL - EFLS) < 1.3; Where, AG12S is the distance on the optical axis from the imaging surface of the first lens to the image source surface of the second lens when the optical system is in the near - focus state, AG12L is the distance on the optical axis from the imaging surface of the first lens to the image source surface of the second lens when the optical system is in the far - focus state, EFLL is the focal length of the optical system in the far - focus state, and EFLS is the focal length of the optical system in the near - focus state.
5. The optical system as claimed in claim 1, characterized in that, The optical system satisfies the relation: 1.2 < L2S2R / L2S1R < 1.5; Where, L2S2R is the radius of curvature of the imaging surface of the second lens at the optical axis, and L2S1R is the radius of curvature of the image source surface of the second lens at the optical axis.
6. The optical system as claimed in claim 1, characterized in that, The optical system satisfies the relation: 1.5 < L1S2R / L1S1R < 1.7; Where, L1S2R is the radius of curvature of the imaging surface of the first lens at the optical axis, and L1S1R is the radius of curvature of the image source surface of the first lens at the optical axis.
7. The optical system as claimed in claim 1, characterized in that, The optical system satisfies the relation: 0 < |(L2S1D / (2*L2S1R)| < 0.7; Where, L2S1D is the maximum effective aperture of the image source surface of the second lens, and L2S1R is the radius of curvature of the image source surface of the second lens at the optical axis.
8. The optical system as claimed in claim 1, characterized in that, The optical system satisfies the relation: 0.8 <CT2 / CT1<0.9; Wherein, CT1 is the thickness of the first lens on the optical axis, and CT2 is the thickness of the second lens on the optical axis.
9. A virtual reality device, characterized in that, It includes a housing and an optical system as described in any one of claims 1 to 8, wherein the optical system is housed within the housing.