Optical system and virtual reality device

Abstract

The application discloses an optical system and a virtual reality device, the optical system has three lenses with refractive power in total, the lenses are sequentially a first lens, a second lens and a third lens from an eye side to an image source side along an optical axis, a polarization reflection film, a phase retarder and a light splitting film are sequentially arranged between an imaging surface of the first lens and a light source surface along the optical axis from the eye side to the image source side, and the optical system satisfies the following relationship: 1.35 <= TTL / IMGH <= 1.65, TTL is the distance from the imaging surface of the first lens to the light source surface of the optical system on the optical axis, and IMGH is half of the diagonal line length of the maximum effective light source area on the light source surface of the optical system. The optical system and the virtual reality device provided by the application can realize the light and thin design of the optical system and improve the imaging performance of the optical system.

Description

Technical Field

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

[0002] With the development and upgrading of advanced optical design and processing technologies, display technologies, and processors, virtual reality (VR) devices are emerging in various forms and types, and their application areas are becoming increasingly widespread. The main working principle of virtual reality products is that the image displayed on the light source is transmitted and magnified through optical lenses before being received by the human eye, which observes a magnified virtual image. In related technologies, image magnification requires a sufficiently long optical path, resulting in a relatively long overall optical length of the optical system. This leads to a larger size for virtual reality devices, reducing user comfort. Summary of the Invention

[0003] This invention provides an optical system and a virtual reality device that can improve the imaging performance of the optical system while achieving a thinner and lighter design.

[0004] To achieve the above objectives, in a first aspect, the present invention provides an optical system comprising three lenses with refractive power, wherein the three lenses with refractive power are, in sequence, a first lens, a second lens, and a third lens along the optical axis from the human eye side to the image source side;

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

[0006] The second lens has negative refractive power, the imaging surface of the second lens is concave near the optical axis, and the image source surface of the second lens is convex near the optical axis;

[0007] The third lens has positive refractive power, the imaging surface of the third lens is concave near the optical axis, and the image source surface of the third lens is convex near the optical axis.

[0008] A polarizing reflective film, a phase retardation film, and a beam splitter are sequentially provided along the optical axis from the human eye side to the image source side between the imaging surface and the light source surface of the first lens;

[0009] Furthermore, the optical system also satisfies the following relationship:

[0010] 1.35≤TTL / IMGH≤1.65;

[0011] Wherein, TTL is the distance on the optical axis from the imaging surface of the first lens to the light source surface of the optical system, i.e., the total length, and IMGH is half the diagonal length of the maximum effective light source area on the light source surface of the optical system.

[0012] By setting the first lens to have positive refractive power, it acts as a light convergent. The combination of a convex surface on both the imaging and image source surfaces near the optical axis further enhances the converging ability of the first lens, facilitating the entry of large-angle light rays into the imaging surface and increasing the maximum field of view of the optical system for better application in virtual reality devices. The second lens has negative refractive power, which helps control the exit angle of light rays from the edge and center fields of view, effectively suppressing aberrations and improving the imaging performance of the optical system. Furthermore, the concave surface on the imaging surface of the second lens near the optical axis facilitates matching the surface shapes of the second and first lenses, reducing lens gaps and simplifying lens assembly and bonding, thus contributing to a thinner and lighter optical system. It is understandable that the convex surface on the image source surface of the second lens near the optical axis and the concave surface on the imaging surface of the third lens also contribute to a thinner and lighter optical system. The third lens has positive refractive power, and its convex surface on the image source surface near the optical axis helps increase the maximum effective light source area of ​​the light source surface while improving the effective utilization rate of the light source. In other words, by selecting an appropriate number of lenses and rationally configuring the refractive power and surface shape of each lens, the optical system can have a large field of view while also being lightweight and thin, thus enabling the optical system to have better imaging effects and improve the comfort of the user's wearing and experience.

[0013] By incorporating polarizing reflective films, phase retarders, and beam splitters, light emitted from the light source undergoes multiple phase delays, transmissions, and reflections, achieving optical path deflection and folding. This increases the optical path length within the optical system, thereby reducing the system's thickness along the optical axis and further facilitating its miniaturization. Furthermore, the optical system satisfies the relationship: 1.35 ≤ TTL / IMGH ≤ 1.65. This allows for a more compact and ultra-thin structure within a relatively large light source surface, meeting miniaturization design requirements. Exceeding the upper limit of this relationship results in an excessively large overall length, increasing the system's volume and hindering miniaturization. Conversely, falling below the lower limit leads to an overly compact structure, increasing the difficulty of aberration correction and potentially reducing imaging performance.

[0014] Secondly, the present invention also provides a virtual reality device, the virtual reality device including a housing and an optical system as described in the first aspect above, the optical system being housed within the housing. The virtual reality device having the optical system can achieve a slim and lightweight design with a small size while maintaining good imaging performance. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments 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 based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the optical system disclosed in the first embodiment of the present invention;

[0017] Figure 2 These are the longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system disclosed in the first embodiment of the present invention;

[0018] Figure 3 This is a schematic diagram of the optical system disclosed in the second embodiment of the present invention;

[0019] Figure 4 These are the longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system disclosed in the second embodiment of the present invention;

[0020] Figure 5 This is a schematic diagram of the optical system disclosed in the third embodiment of the present invention;

[0021] Figure 6 These are the longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system disclosed in the third embodiment of the present invention;

[0022] Figure 7 This is a schematic diagram of the optical system disclosed in the fourth embodiment of the present invention;

[0023] Figure 8 These are the longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system disclosed in the fourth embodiment of the present invention;

[0024] Figure 9 This is a schematic diagram of the optical system disclosed in the fifth embodiment of the present invention;

[0025] Figure 10 These are the longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system disclosed in the fifth embodiment of the present invention;

[0026] Figure 11 This is a schematic diagram of the optical system disclosed in the sixth embodiment of the present invention;

[0027] Figure 12 These are the longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system disclosed in the sixth embodiment of the present invention;

[0028] Figure 13 This is a schematic diagram of the optical system disclosed in the seventh embodiment of the present invention;

[0029] Figure 14 These are the longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system disclosed in the seventh embodiment of the present invention;

[0030] Figure 15 This is a schematic diagram of the structure of the virtual reality device disclosed in this invention. Detailed Implementation

[0031] 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 some embodiments of the present invention, and not all embodiments. 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.

[0032] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation.

[0033] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0034] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0035] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0036] The technical solution of the present invention will be further described below with reference to the embodiments and accompanying drawings.

[0037] Please see Figure 1 According to a first aspect of the present invention, an optical system 100 is provided, the optical system 100 having three refractive lenses, the three refractive lenses being arranged sequentially along the optical axis O from the eye side to the image source side as a first lens L1, a second lens L2, and a third lens L3. The first lens L1 has positive refractive power, its imaging surface S1 is convex near the optical axis, and its image source surface S2 is convex near the optical axis; the second lens L2 has negative refractive power, its imaging surface S3 is concave near the optical axis, and its image source surface S4 is convex near the optical axis; the third lens L3 has positive refractive power, its imaging surface S5 is concave near the optical axis, and its image source surface S6 is convex near the optical axis.

[0038] By setting the first lens L1 to have positive refractive power, it serves to converge light rays. Combined with the convex surface configuration of both the imaging surface S1 and the image source surface S2 near the optical axis, the converging ability of the first lens L1 is further enhanced, facilitating the entry of large-angle light rays into the imaging surface and increasing the maximum field of view of the optical system 100 for better application in virtual reality devices. The second lens L2 has negative refractive power, which helps control the exit angle of light rays from the edge and center fields of view, effectively suppressing aberrations and improving the imaging performance of the optical system 100. Furthermore, the concave surface configuration of the imaging surface S3 of the second lens L2 near the optical axis facilitates the matching of the surface configurations of the second lens L2 and the first lens L1, reducing lens gaps and facilitating lens assembly and bonding, thus contributing to the thinner and lighter design of the optical system 100. It is understood that the convex surface configuration of the image source surface S4 of the second lens L2 near the optical axis and the concave surface configuration of the imaging surface S5 of the third lens L3 near the optical axis also contribute to the thinner and lighter design of the optical system 100. The third lens L3 has positive refractive power, and its image source surface S6 is convex near the optical axis. This helps to increase the maximum effective light source area of ​​the light source surface IMG while improving the effective utilization rate of the light source. In other words, by selecting an appropriate number of lenses and rationally configuring the refractive power and surface shape of each lens, the optical system 100 can have a large field of view while also being lightweight and thin. This allows the optical system 100 to have better imaging effects, thereby improving the user's wearing and experience comfort.

[0039] In some embodiments, a polarizing reflective film, a phase retarder, and a beam splitter are sequentially provided along the optical axis from the human eye side to the image source side between the imaging surface S1 and the light source surface IMG of the first lens L1. This allows the light emitted from the light source surface IMG to undergo multiple phase delays, transmissions, and reflections, thereby achieving optical path deflection and folding, increasing the optical path length of the light within the optical system 100, and thus reducing the thickness of the optical system 100 along the optical axis O, further contributing to the thinning and lightening of the optical system 100.

[0040] When light forms an image along the light path, the light emitted from the light source surface IMG is first circularly polarized light. For example, the display screen includes a linear polarizer and a phase retardation plate, so the light emitted from the light source surface IMG of the display screen is first circularly polarized light. Further, from the eye side to the image source side, a polarizing reflective film, a phase retardation plate, and a beam splitter are sequentially provided. For example, the polarizing reflective film is located on the imaging surface S3 of the second lens L2, the phase retardation plate is located on the image source surface S4 of the second lens L2 (preferably a quarter-wave plate), and the beam splitter is located on the image source surface S6 of the third lens L3 (preferably a semi-reflective, semi-transparent film). Thus, the first circularly polarized light is polarized after passing through the beam splitter and the third lens L3. The vibration state remains unchanged. After passing through the quarter-wave plate, the first circularly polarized light becomes the first linearly polarized light. After passing through the second lens L2, the first linearly polarized light is reflected by the polarizing reflection film on the imaging surface S3 of the second lens L2. After passing through the second lens L2 and the quarter-wave plate again, the first linearly polarized light becomes the second circularly polarized light under the action of the quarter-wave plate. After passing through the third lens L3, the second circularly polarized light is reflected again by the beam splitter. The deflection direction of the second circularly polarized light is opposite to the rotation of the first circularly polarized light. After passing through the third lens L3, the second circularly polarized light passes through the quarter-wave plate on the image source surface S4 of the second lens L2 again and changes from the second circularly polarized light to the second linearly polarized light. The second linearly polarized light is transmitted to the image plane (not shown in the figure) after passing through the second lens L2, the polarizing reflection film and the first lens L1 in sequence. That is, the virtual reality device completes the image formation in the human eye.

[0041] It should be noted that the above exemplary description is only for the purpose of explaining the principle and does not limit the position of the polarizing reflective film, the phase retarder, and the beam splitter. For example, the polarizing reflective film can be disposed on the imaging surface S1 of the first lens L1, the phase retarder can be disposed on the image source surface S2 of the first lens L1, and the beam splitter can be disposed on the imaging surface S5 of the third lens L3; or, the polarizing reflective film and the phase retarder can be disposed sequentially on the image source surface S2 of the first lens L1, and the beam splitter can be disposed on the image source surface S4 of the second lens L2. This is not an exhaustive list, as long as the three are disposed sequentially from the human eye side to the image source side. The phase retarder is not limited to a quarter-wave plate, and other phase retardation structures such as a half-wave plate can also be used.

[0042] In some embodiments, the first lens L1 and the third lens L3 are made of plastic, and the second lens L2 is made of glass. In other embodiments, the first lens L1 and the second lens L2 are made of plastic, and the third lens L3 is made of glass. Both methods allow the optical system 100 to have low temperature sensitivity while maintaining a light overall weight. It is understood that the lens material can be selected according to actual needs; for example, all lenses may be made of plastic, all lenses may be made of glass, or a mixture of different materials may be used. Therefore, this embodiment does not impose specific limitations.

[0043] In some embodiments, except for the imaging surface S1 of the first lens L1 and the image source surface S6 of the third lens L3 which are aspherical, the other imaging surfaces / or image source surfaces of the first lens L1, the second lens L2, and the third lens L3 can be spherical. The combination of spherical and aspherical surfaces allows for more flexible design of the object side and / or image side of the lens, enabling each lens to effectively solve problems such as unclear imaging, distorted field of view, and narrow field of view even when it is small and thin. It can achieve good imaging quality of the lens group without setting too many lenses, and also helps to shorten the length of the optical system 100. It is understandable that spherical lenses have a simple manufacturing process, low production cost, and are easy to design with flexible lens surface shapes, thereby improving the imaging resolution of each lens. Aspherical design allows for more flexible design of the object side and / or image side of the lens, enabling the lens to effectively solve problems such as unclear imaging, distorted field of view, and narrow field of view even when it is small and thin. It can achieve good imaging quality without setting too many lenses and also helps to shorten the length of the optical system 100. Therefore, the surface of each lens in the optical system 100 can be spherical, aspherical, or any combination of spherical and aspherical, selected according to actual needs. Therefore, no specific limitation is made in this embodiment.

[0044] In some embodiments, the optical system 100 further includes a protective glass IR, which is disposed between the image source surface S6 of the third lens L3 and the light source surface IMG of the optical system 100, and can protect the display screen. It is understood that by coating the surface of the protective glass IR, unpolarized light emitted from the display screen can be converted into first circularly polarized light after passing through the protective glass. The protective glass IR can be part of the optical system 100 or can be removed from the optical system 100, but when the protective glass IR is removed, the total optical length of the optical system 100 remains unchanged.

[0045] In some embodiments, the optical system 100 satisfies the following relationship: 1.35 ≤ TTL / IMGH ≤ 1.65; where TTL is the distance on the optical axis O from the imaging surface S1 of the first lens L1 to the light source surface IMG of the optical system 100, i.e., the total optical length, and IMGH is half the diagonal length of the maximum effective light source area on the light source surface IMG of the optical system 100. The value of TTL / IMGH can be 1.358, 1.417, 1.475, 1.533, 1.592, or 1.648, etc.

[0046] Satisfying the above relationship allows the optical system 100 to have a larger light source surface (IMG), resulting in a more compact structure and ultra-thin characteristics, thus meeting the miniaturization design requirements. Exceeding the upper limit of the relationship leads to an excessively large overall length of the optical system 100, increasing its volume and hindering its miniaturization. Conversely, falling below the lower limit results in an overly compact structure, making aberration correction more difficult and potentially reducing the imaging performance of the optical system 100.

[0047] In some embodiments, the optical system 100 satisfies the following relationship: 85deg≤FOV≤95deg; where FOV is the maximum field of view of the optical system 100. The value of FOV can be 85, 87, 89, 91, 93 or 95, etc., and the unit is deg.

[0048] If the above relationship is satisfied, users can obtain a visually immersive experience. When the upper limit of the relationship is exceeded, the field of view of the optical system 100 is too large, resulting in excessive distortion at the edge of the field of view, causing distortion at the periphery of the image; when the lower limit of the relationship is exceeded, the field of view of the optical system 100 is too small, which is not conducive to the application of the optical system 100 in VR lenses.

[0049] In some embodiments, the optical system 100 satisfies the following relationships: 0 ≤ CT12 / CT2 ≤ 0.5; 0 ≤ CT23 / CT2 ≤ 0.5; where CT12 is the distance on the optical axis O from the image source surface S2 of the first lens L1 to the imaging surface S3 of the second lens L2, CT2 is the thickness of the second lens L2 on the optical axis O, and CT23 is the distance on the optical axis O from the image source surface S4 of the second lens L2 to the imaging surface S5 of the third lens L3. The value of CT12 / CT2 can be 0, 0.1, 0.2, 0.3, 0.4, or 0.5, etc.; the value of CT23 / CT2 can be 0, 0.1, 0.2, 0.3, 0.4, or 0.5, etc.

[0050] Satisfying the above relationships, the second lens L2 has a suitable center thickness while maintaining a small gap or close fit with the first lens L1 and the third lens L3. This not only avoids the loss of light transmission capability when the gap is wide, but also helps the optical system 100 maintain a compact structure, achieving a thinner and lighter optical system. Furthermore, the optical system 100 satisfies the relationships: 0.1≤CT12 / CT2≤0.3; 0.05≤CT23 / CT2≤0.25. This further ensures a small gap or tight fit between the first lens L1 and the third lens L3, thereby guaranteeing the compact structure of the optical system 100 and further achieving a thinner and lighter optical system.

[0051] In some embodiments, the optical system 100 satisfies the following relationship: 3.4 ≤ f1 / f ≤ 5; where f1 is the focal length of the first lens L1 and f is the focal length of the optical system 100. The value of f1 / f can be 3.44, 3.64, 3.84, 4, 4.2, 4.4, 4.6, 4.8, or 5, etc.

[0052] Satisfying the above relationship, the refractive power contribution of the first lens L1 is reasonably configured, which is beneficial to correcting the aberrations produced by the second lens L2 and the third lens L3, and thus beneficial to the overall aberration balance of the optical system 100. In addition, it is also beneficial to reduce the deflection angle of the edge field of view, which can realize the smooth transition of light to the image plane, thereby improving the imaging quality.

[0053] In some embodiments, the optical system 100 satisfies the following relationship: -40 ≤ R11 / R12 ≤ -2; where R11 is the radius of curvature of the imaging surface S1 of the first lens L1 at the optical axis O, and R12 is the radius of curvature of the image source surface S2 of the first lens L1 at the optical axis O. The value of R11 / R12 can be -40, -35, -30, -20, -15, -10, -5.2, -4.4, -3.6, -2.8, or -2, etc.

[0054] Satisfying the above relationship, the imaging surface S1 and the image source surface S2 of the first lens L1 are reasonably configured at the near optical axis, which is conducive to maintaining a relatively uniform thickness of the first lens L1. It can reasonably balance the optical path difference between the edge field of view and the center field of view of the optical system 100, thereby reasonably correcting the field curvature and astigmatism. At the same time, the reasonable surface curvature is also conducive to the attachment of the required waveplate or film layer.

[0055] In some embodiments, the optical system 100 satisfies the following relationship: 30deg≤P32≤45deg; P32 is the angle between the tangent at the maximum effective aperture of the image source surface S6 of the third lens L3 and the optical axis O. The value of P32 can be 30, 33, 36, 39, 42 or 45, etc., in deg.

[0056] Satisfying the above relationship, the angle between the tangent at the maximum effective aperture of the image source surface S6 of the third lens L3 and the optical axis O is reasonably configured, which helps to reduce the surface complexity of the third lens L3 at the maximum effective aperture, thereby reducing the processing difficulty and assembly sensitivity of the third lens L3, improving the assembly yield, and also facilitating the adhesion of the required film layer.

[0057] In some embodiments, the optical system 100 satisfies the following relationship: 0.75 ≤ D11 / D32 ≤ 0.9; where D11 is half the maximum effective aperture of the imaging surface S1 of the first lens L1, and D32 is half the maximum effective aperture of the image source surface S6 of the third lens L3. The value of D11 / D32 can be 0.755, 0.78, 0.794, 0.808, 0.822, 0.836, 0.85, or 0.895, etc.

[0058] By satisfying the above relationship, the ratio of the maximum effective aperture of the imaging surface S1 of the first lens L1 to the maximum effective aperture of the image source surface S6 of the third lens L3 can be reasonably configured, avoiding an excessive difference in the maximum effective aperture between the first lens L1 and the third lens L3. This allows light rays from the edge field of view to enter the imaging surface S1 of the first lens L1 from the image source surface S6 of the third lens L3 with a gentler change trend, reducing the risk of distortion in the optical system 100.

[0059] In some embodiments, the optical system 100 satisfies the following relationships: 0.6 ≤ f1 / f3 ≤ 0.8; -2 ≤ f2 / f3 ≤ -1; where f1 is the focal length of the first lens L1, f2 is the focal length of the second lens L2, and f3 is the focal length of the third lens L3. The value of f1 / f3 can be 0.6, 0.64, 0.68, 0.7, 0.72, 0.74, 0.76, 0.78, or 0.8; the value of f2 / f3 can be -2, -1.8, -1.6, -1.4, -1.2, or -1, etc.

[0060] By satisfying the above relationship, the refractive forces of the first lens L1, the second lens L2, and the third lens L3 are rationally configured, which can balance the distribution of refractive forces among the lenses, thereby effectively balancing and controlling the spherical aberration of the optical system 100, reducing the sensitivity of the optical system 100, and improving the imaging quality of the optical system 100.

[0061] In some embodiments, the optical system 100 satisfies the following relationship: 1.75 ≤ D32 / IMGH ≤ 1.95; where D32 is half the maximum effective aperture of the image source surface S6 of the third lens L3, and IMGH is half the diagonal length of the maximum effective light source region on the light source surface IMG of the optical system 100. The value of D32 / IMGH can be 1.783, 1.817, 1.851, 1.883, 1.917, or 1.945, etc.

[0062] Satisfying the above relationship allows the optical system 100 to have a large-sized light source surface IMG. At the same time, the large-sized light source surface IMG has sufficient aperture space for deflection, which further facilitates the smooth transition of light from the light source surface IMG to the image plane, reduces the degree of light deflection, and also helps to reduce the angle of light incident on the image plane, thereby improving the imaging quality of the optical system 100.

[0063] The optical system 100 of this embodiment will be described in detail below with reference to specific parameters.

[0064] First Embodiment

[0065] A schematic diagram of the structure of the optical system 100 disclosed in the first embodiment of the present invention is shown below. Figure 1 As shown, the optical system 100 includes a first lens L1, a polarizing reflective film, a second lens L2, a quarter-wave plate, a third lens L3, a beam splitter, and a protective glass IR, arranged sequentially along the optical axis O from the eye side to the image source side. The refractive power, surface shape, and materials of the first lens L1, the second lens L2, and the third lens L3 are as described in the specific embodiments above, and will not be repeated here.

[0066] Specifically, taking the focal length f=17.53mm, the maximum field of view FOV=88deg, the total length TTL=19.987mm, and half the diagonal length of the maximum effective light source area on the light source surface IMG of the optical system 100, IMGH=12.504mm, as examples, other parameters of the optical system 100 are given in Table 1 below. The elements along the optical axis O of the optical system 100 from the human eye side to the image source side are arranged sequentially according to the order of the elements in Table 1 from top to bottom. In the same lens, the surface with the smaller surface number is the imaging surface of the lens, and the surface with the larger surface number is the image source surface of the lens. For example, surface numbers 1 and 2 correspond to the imaging surface S1 and image source surface S2 of the first lens L1, respectively. The Y-radius in Table 1 is the radius of curvature of the imaging surface or image source surface with the corresponding surface number at the optical axis O. The first value in the "thickness" parameter column of the lens is the thickness of the lens on the optical axis O, and the second value is the distance from the image source surface of the lens to the rear surface on the optical axis O. It can be understood that the units for Y-radius, thickness, and focal length in Table 1 are all mm. Furthermore, the reference wavelength for the focal length of each lens in Table 1 is 623 nm, and the reference wavelength for the refractive index and Abbe number of each lens is 587.56 nm. A polarizing reflective film connects the first lens L1 and the second lens L2, a quarter-wave plate connects the second lens L2 and the third lens L3, and a beam-splitting film is located on the image source surface S6 of the third lens L3. Since its thickness is negligible, it is not shown in Table 1. Thus, there is no gap between the first lens L1 and the third lens L3.

[0067] Table 1

[0068]

[0069] In the first embodiment, the imaging surface S1 of the first lens L1 and the image source surface S6 of the third lens L3 are aspherical surfaces, and the surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0070]

[0071] Where x is the distance vector from the vertex of the aspherical surface at a height h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the Y radius R in Table 1 above); K is the conic coefficient; Ai is the correction coefficient corresponding to the i-th higher-order term of the aspherical surface. Table 2 gives the conic coefficients of the imaging surface S1 of the first lens L1 and the image source surface S6 of the third lens L3 that can be used in the first embodiment, as well as the higher-order coefficients A4, A6, A8, A10, and A12 of the aspherical mirror.

[0072] Table 2

[0073]

[0074] Please see Figure 2 (A) in the middle Figure 2 Image (A) shows the longitudinal spherical aberration curves of the optical system 100 in the first embodiment at wavelengths of 454 nm, 546 nm, and 623 nm. Figure 2 In (A), the horizontal axis along the X-axis represents the focal point offset in mm, and the vertical axis along the Y-axis represents the normalized field of view. Figure 2 As can be seen from (A) in the first embodiment, the spherical aberration value of the optical system 100 is better, indicating that the imaging quality of the optical system 100 in this embodiment is better.

[0075] Please see Figure 2 (B) Figure 2 (B) in the figure is an astigmatism diagram of the optical system 100 in the first embodiment at a wavelength of 623 nm. Figure 2 In (B) of the diagram, the horizontal axis along the X-axis represents the focal point offset in mm, and the vertical axis along the Y-axis represents the image height in mm. In the astigmatism curve diagram, T represents the curvature of the image plane in the meridional direction, and S represents the curvature of the image plane in the sagittal direction. Figure 2 As can be seen from (B) in the figure, the astigmatism of the optical system 100 is well compensated at the wavelength of 623nm.

[0076] Please see Figure 2(C) in Figure 2 In Figure (C), the distortion diagram of the optical system 100 in the first embodiment at a wavelength of 623 nm is shown. The horizontal axis along the X-axis represents the distortion (%), and the vertical axis along the Y-axis represents the image height (mm). Figure 2 As can be seen from (C), at the wavelength of 623nm, the distortion of the optical system 100 is well corrected.

[0077] Second Embodiment

[0078] Please refer to Figure 3 , Figure 3 This is a schematic diagram of the optical system 100 according to a second embodiment of the present invention. The optical system 100 includes a first lens L1, a polarizing reflective film, a second lens L2, a quarter-wave plate, a third lens L3, a beam splitter, and a protective glass IR, arranged sequentially along the optical axis O from the eye side to the image source side. The refractive power, surface shape, and materials of the first lens L1, the second lens L2, and the third lens L3 are as described in the specific embodiments above, and will not be repeated here.

[0079] In the second embodiment, taking the focal length f=16.8mm, the maximum field of view FOV=92deg, the total length TTL=19.337mm, and half the diagonal length of the maximum effective light source area on the light source surface IMG of the optical system 100, IMGH=125.501mm, as examples, the other parameters in this second embodiment are given in Table 3 below, and the definitions of each parameter can be derived from the description of the foregoing embodiments, and will not be repeated here.

[0080] Table 3

[0081]

[0082] In the second embodiment, Table 4 provides the conic coefficients and aspherical mirror higher-order coefficients A4, A6, A8, A10 and A12 of the imaging surface S1 of the first lens L1 and the image source surface S6 of the third lens L3 that can be used in the first embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0083] Table 4

[0084]

[0085] Please see Figure 4 , Figure 4 The longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system 100 of the second embodiment are shown. For specific definitions, please refer to the description in the first embodiment; they will not be repeated here. Figure 4As can be seen from (A) in the diagram, the optical system 100 in the second embodiment has a better spherical aberration value, indicating that the optical system 100 in this embodiment has better imaging quality. Figure 4 As can be seen from (B) in the diagram, the astigmatism of optical system 100 is well compensated at a wavelength of 623 nm. Figure 4 As can be seen from (C), the distortion of the optical system 100 is well corrected at a wavelength of 623nm.

[0086] Third Embodiment

[0087] Please refer to Figure 5 , Figure 5 This is a schematic diagram of the optical system 100 according to a third embodiment of the present invention. The optical system 100 includes a first lens L1, a polarizing reflective film, a second lens L2, a quarter-wave plate, a third lens L3, a beam splitter, and a protective glass IR, arranged sequentially along the optical axis O from the eye side to the image source side. The refractive power, surface shape, and materials of the first lens L1, the second lens L2, and the third lens L3 are as described in the specific embodiments above, and will not be repeated here.

[0088] In the third embodiment, the focal length of the optical system 100 is f=17.53mm, the maximum field of view (FOV) of the optical system 100 is 88deg, the total length (TTL) of the optical system 100 is 20.293mm, and half the diagonal length of the maximum effective light source area on the light source surface (IMG) of the optical system 100 is IGH=12.511mm. Other parameters in this third embodiment are given in Table 5 below, and the definitions of each parameter can be derived from the descriptions of the foregoing embodiments, and will not be repeated here. It should be noted that the difference between the third embodiment and the first embodiment is that the polarizing reflective film is disposed on the image source surface (S2) of the first lens L1, and there is a gap between it and the imaging surface (S3) of the second lens L2.

[0089] Table 5

[0090]

[0091] In the third embodiment, Table 6 provides the conic coefficients and aspherical mirror higher-order coefficients A4, A6, A8, A10 and A12 of the imaging surface S1 of the first lens L1 and the image source surface S6 of the third lens L3 that can be used in the first embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0092] Table 6

[0093]

[0094] Please see Figure 6 , Figure 6The longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system 100 of the third embodiment are shown. For specific definitions, please refer to the description in the first embodiment; they will not be repeated here. Figure 6 As can be seen from (A) in the figure, the spherical aberration value of the optical system 100 in the third embodiment is better, indicating that the imaging quality of the optical system 100 in this embodiment is better. Figure 6 As can be seen from (B) in the diagram, the astigmatism of optical system 100 is well compensated at a wavelength of 623 nm. Figure 6 As can be seen from (C), the distortion of the optical system 100 is well corrected at a wavelength of 623nm.

[0095] Fourth embodiment

[0096] Please see Figure 7 , Figure 7 This is a schematic diagram of the optical system 100 according to the fourth embodiment of the present invention. The optical system 100 includes a first lens L1, a polarizing reflective film, a second lens L2, a quarter-wave plate, a third lens L3, a beam splitter, and a protective glass IR, arranged sequentially along the optical axis O from the eye side to the image source side. The refractive power, surface shape, and materials of the first lens L1, the second lens L2, and the third lens L3 are as described in the specific embodiments above, and will not be repeated here.

[0097] In the fourth embodiment, the focal length of the optical system 100 is f=17.48mm, the maximum field of view (FOV) of the optical system 100 is 88deg, the total length (TTL) of the optical system 100 is 19.647mm, and half the diagonal length of the maximum effective light source area on the light source surface (IMG) of the optical system 100 is IGH=12.545mm. Other parameters in this fourth embodiment are given in Table 7 below, and the definitions of each parameter can be derived from the descriptions of the foregoing embodiments, and will not be repeated here. It should be noted that the difference between the fourth embodiment and the first embodiment is that the polarizing reflective film is disposed on the image source surface (S2) of the first lens L1, and there is a gap between it and the imaging surface (S3) of the second lens L2; ​​the quarter-wave plate is disposed on the image source surface (S4) of the second lens L2, and there is a gap between it and the imaging surface (S5) of the third lens L3.

[0098] Table 7

[0099]

[0100] In the fourth embodiment, Table 8 provides the conic coefficients and aspherical mirror higher-order coefficients A4, A6, A8, A10 and A12 of the imaging surface S1 of the first lens L1 and the image source surface S6 of the third lens L3 that can be used in the first embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0101] Table 8

[0102]

[0103] Please see Figure 8 , Figure 8 The longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system 100 of the fourth embodiment are shown. For specific definitions, please refer to the description in the first embodiment; they will not be repeated here. Figure 8 As can be seen from (A) in the figure, the spherical aberration value of the optical system 100 in the fourth embodiment is better, indicating that the imaging quality of the optical system 100 in this embodiment is better. Figure 8 As can be seen from (B) in the diagram, the astigmatism of optical system 100 is well compensated at a wavelength of 623 nm. Figure 8 As can be seen from (C), the distortion of the optical system 100 is well corrected at a wavelength of 623nm.

[0104] Fifth embodiment

[0105] Please see Figure 9 , Figure 9 This is a schematic diagram of the optical system 100 according to the fifth embodiment of the present invention. The optical system 100 includes a first lens L1, a polarizing reflective film, a second lens L2, a quarter-wave plate, a third lens L3, a beam splitter, and a protective glass IR, arranged sequentially along the optical axis O from the eye side to the image source side. The refractive power, surface shape, and materials of the first lens L1, the second lens L2, and the third lens L3 are as described in the specific embodiments above, and will not be repeated here.

[0106] In the fifth embodiment, the focal length f = 17.33 mm, the maximum field of view FOV = 88 degrees, the total length TTL = 18.775 mm, and half the diagonal length of the maximum effective light source area on the light source surface IMG of the optical system 100, IMGH = 12.514 mm, are taken as examples. Other parameters in this fifth embodiment are given in Table 9 below, and the definitions of each parameter can be derived from the descriptions of the foregoing embodiments, and will not be repeated here. It should be noted that the difference between the fifth embodiment and the first embodiment is that the quarter-wave plate is disposed on the image source surface S4 of the second lens L2, and there is a gap between it and the imaging surface S5 of the third lens L3.

[0107] Table 9

[0108]

[0109] In the fifth embodiment, Table 10 provides the conic coefficients and aspherical mirror higher-order coefficients A4, A6, A8, A10 and A12 of the imaging surface S1 of the first lens L1 and the image source surface S6 of the third lens L3 that can be used in the first embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0110] Table 10

[0111]

[0112] Please see Figure 10 , Figure 10 The longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system 100 of the fifth embodiment are shown. For specific definitions, please refer to the description in the first embodiment; they will not be repeated here. Figure 10 As can be seen from (A) in the figure, the spherical aberration value of the optical system 100 in the fifth embodiment is better, indicating that the imaging quality of the optical system 100 in this embodiment is better. Figure 10 As can be seen from (B) in the diagram, the astigmatism of optical system 100 is well compensated at a wavelength of 623 nm. Figure 10 As can be seen from (C), the distortion of the optical system 100 is well corrected at a wavelength of 623nm.

[0113] Sixth Embodiment

[0114] Please see Figure 11 , Figure 11 This is a schematic diagram of the optical system 100 according to the sixth embodiment of the present invention. The optical system 100 includes a first lens L1, a polarizing reflective film, a second lens L2, a quarter-wave plate, a third lens L3, a beam splitter, and a protective glass IR, arranged sequentially along the optical axis O from the eye side to the image source side. The refractive power, surface shape, and materials of the first lens L1, the second lens L2, and the third lens L3 are as described in the specific embodiments above, and will not be repeated here.

[0115] In the sixth embodiment, the focal length of the optical system 100 is f=17.327mm, the maximum field of view (FOV) of the optical system 100 is 90deg, the total length (TTL) of the optical system 100 is 19.047mm, and half the diagonal length of the maximum effective light source area on the light source surface (IMG) of the optical system 100 is IGH=12.5mm. Other parameters in this sixth embodiment are given in Table 11 below, and the definitions of each parameter can be derived from the descriptions of the preceding embodiments, and will not be repeated here. It should be noted that the difference between the sixth embodiment and the first embodiment is that the polarizing reflective film is disposed on the image source surface (S2) of the first lens L1, and there is a gap between it and the imaging surface (S3) of the second lens L2. The reference wavelength for the focal length of each lens is 600nm.

[0116] Table 11

[0117]

[0118] In the sixth embodiment, Table 12 provides the conic coefficients and aspherical mirror higher-order coefficients A4, A6, A8, A10, A12 and A14 of the imaging surface S1 and image source surface S2 of the first lens L1 and the image source surface S6 of the third lens L3, which can be used in the first embodiment. The aspherical surface shape can be defined by the formula given in the first embodiment.

[0119] Table 12

[0120]

[0121] Please see Figure 12 , Figure 12 The longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system 100 of the sixth embodiment are shown. For specific definitions, please refer to the description in the first embodiment; they will not be repeated here. Figure 12 As can be seen from (A) in the figure, the spherical aberration value of the optical system 100 in the sixth embodiment is better, indicating that the imaging quality of the optical system 100 in this embodiment is better. Figure 12 As can be seen from (B) in the diagram, the astigmatism of optical system 100 is well compensated at a wavelength of 600 nm. Figure 12 As can be seen from (C) in the figure, the distortion of the optical system 100 is well corrected at a wavelength of 600nm.

[0122] Seventh Embodiment

[0123] Please see Figure 13 , Figure 13 This is a schematic diagram of the optical system 100 according to the seventh embodiment of the present invention. The optical system 100 includes a first lens L1, a polarizing reflective film, a second lens L2, a quarter-wave plate, a third lens L3, a beam splitter, and a protective glass IR, arranged sequentially along the optical axis O from the eye side to the image source side. The refractive power, surface shape, and materials of the first lens L1, the second lens L2, and the third lens L3 are as described in the specific embodiments above, and will not be repeated here.

[0124] In the seventh embodiment, the focal length f = 16.92 mm, the maximum field of view (FOV) of the optical system 100 = 93 degrees, the total length (TTL) of the optical system 100 = 17.127 mm, and half the diagonal length of the maximum effective light source area on the light source surface (IMG) of the optical system 100 (IMGH = 12.5 mm) are taken as examples. Other parameters in this seventh embodiment are given in Table 13 below, and the definitions of each parameter can be derived from the descriptions of the foregoing embodiments, and will not be repeated here. It should be noted that the difference between the seventh embodiment and the first embodiment is that the polarizing reflective film is disposed on the image source surface (S2) of the first lens L1, and there is a gap between it and the imaging surface (S3) of the second lens L2. The reference wavelength for the focal length of each lens is 600 nm.

[0125] Table 13

[0126]

[0127] In the seventh embodiment, Table 14 provides the conic coefficients and aspherical mirror higher-order coefficients A4, A6, A8, A10, A12 and A14 of the imaging surface S1 and image source surface S2 of the first lens L1 and the imaging surface S5 of the second lens L2, which can be used in the first embodiment. The aspherical surface shape can be defined by the formula given in the first embodiment.

[0128] Table 14

[0129]

[0130] Please see Figure 14 , Figure 14 The longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system 100 of the seventh embodiment are shown. For specific definitions, please refer to the description in the first embodiment; they will not be repeated here. Figure 12 As can be seen from (A) in the figure, the spherical aberration value of the optical system 100 in the sixth embodiment is better, indicating that the imaging quality of the optical system 100 in this embodiment is better. Figure 12 As can be seen from (B) in the diagram, the astigmatism of optical system 100 is well compensated at a wavelength of 600 nm. Figure 12 As can be seen from (C) in the figure, the distortion of the optical system 100 is well corrected at a wavelength of 600nm.

[0131] Please refer to Table 15, which summarizes the ratios of the relationships in the first to seventh embodiments of this application.

[0132] Table 15

[0133]

[0134] like Figure 15As shown, the present invention also provides a virtual reality device 200, which includes a housing 201 and an optical system 100 as described in the first aspect above, the optical system 100 being housed within the housing 201. The virtual reality device having the optical system 100 can achieve a slim and lightweight design with a small size while maintaining good imaging performance.

[0135] The foregoing has provided a detailed description of an optical system 100 and a virtual reality device disclosed in the embodiments of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the optical system 100 and the virtual reality device of the present invention and their core ideas. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An optical system, characterized in that, The optical system has three lenses with refractive power, which are arranged sequentially along the optical axis from the human eye side to the image source side as the first lens, the second lens, and the third lens; The first lens has positive refractive power, the imaging surface of the first lens is convex near the optical axis, and the image source surface of the first lens is convex near the optical axis. The second lens has negative refractive power, the imaging surface of the second lens is concave near the optical axis, and the image source surface of the second lens is convex near the optical axis; The third lens has positive refractive power, the imaging surface of the third lens is concave near the optical axis, and the image source surface of the third lens is convex near the optical axis. A polarizing reflective film, a phase retardation film, and a beam splitter are sequentially provided along the optical axis from the human eye side to the image source side between the imaging surface and the light source surface of the first lens; Furthermore, the optical system also satisfies the following relationship: 1.35≤TTL / IMGH≤1.65; -40≤R11 / R12≤-2; Wherein, TTL is the distance on the optical axis from the imaging surface of the first lens to the light source surface of the optical system, IMGH is half the diagonal length of the maximum effective light source area on the light source surface of the optical system, R11 is the radius of curvature of the imaging surface of the first lens on the optical axis, and R12 is the radius of curvature of the image source surface of the first lens on the optical axis.

2. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationship: 85deg≤FOV≤95deg; Wherein, FOV is the maximum field of view of the optical system.

3. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationship: 0 ≤ CT12 / CT2 ≤ 0.5; 0 ≤ CT23 / CT2 ≤ 0.5; Wherein, CT12 is the distance on the optical axis from the image source surface of the first lens to the imaging surface of the second lens, CT2 is the thickness of the second lens on the optical axis, and CT23 is the distance on the optical axis from the image source surface of the second lens to the imaging surface of the third lens.

4. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationship: 3.4≤f1 / f≤5; Where f1 is the focal length of the first lens, and f is the focal length of the optical system.

5. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationship: 30deg≤P32≤45deg; Wherein, P32 is the angle between the tangent at the maximum effective aperture of the image source surface of the third lens and the optical axis.

6. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationship: 0.75≤D11 / D32≤0.9; Wherein, D11 is half of the maximum effective aperture of the imaging surface of the first lens, and D32 is half of the maximum effective aperture of the image source surface of the third lens.

7. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationship: 0.6≤f1 / f3≤0.8; -2≤f2 / f3≤-1; Where f1 is the focal length of the first lens, f2 is the focal length of the second lens, and f3 is the focal length of the third lens.

8. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationship: 1.75≤D32 / IMGH≤1.95; Wherein, D32 is half of the maximum effective aperture of the image source surface of the third lens.

9. A virtual reality device, characterized in that, The virtual reality device includes a housing and an optical system as described in any one of claims 1-8, the optical system being housed within the housing.

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