Lens group, optical module and near-to-eye display equipment

Abstract

The utility model provides a lens group, an optical module for near-eye display equipment and the near-eye display equipment, the focal length of the lens group is F, the lens group comprises a first lens, a second lens and a third lens which are coaxially arranged in sequence from an object side to an image side, the first lens has positive focal power, and the focal length f1 satisfies 1.1 F < = f1 < = 1.4 F. The second lens has negative focal power, and the focal length f2 satisfies 10F < = f2 < = 20F. And the focal length f3 of the third lens is more than or equal to 6F and less than or equal to 16F. The lens group further comprises a partial reflection device and a reflection polarization device, the partial reflection device is arranged on the side, away from the second lens, of the first lens, and the reflection polarization device is arranged between the second lens and the third lens. According to the embodiment of the utility model, the size relationship between the focal lengths of the first lens, the second lens and the third lens and the focal length F of the lens group is restrained, so that the imaging definition of the lens group is improved, the luminous efficiency of signal light is improved, the lens group is suitable for near-eye display equipment, the field of view of the near-eye display equipment is improved, and the chromatic aberration is reduced.

Description

Technical Field

[0001] The utility model generally relates to the technical field of optical lenses, and in particular to a lens group, an optical module for a near-eye display device, and a near-eye display device. Background Art

[0002] Near-eye display devices such as VR (Virtual Reality) glasses and AR (Augmented Reality) glasses make comprehensive use of computer graphics systems and various display and optical components, combined with the physiological characteristics of human visual persistence, to provide users with an immersive and interactive visual experience.

[0003] The lenses in the optical lens are prone to uneven stress, which causes the lens surface shape to change with the stress changes inside the lens, affecting the image quality under long-term use. The low-stress materials used to design VR glasses are relatively limited. Multiple lenses in the optical magnification module are often made of the same material, and the available refractive index is limited. The vertical axis aberration of the optical magnification module has a great impact on the image quality of the entire system. The larger the field of view of the near-eye display device, the more serious the chromatic aberration may be, affecting the clarity of the large field of view curve.

[0004] The contents of the background technology section are merely the technologies known to the inventors and do not necessarily represent the prior art in the field. Utility Model Content

[0005] In view of one or more defects in the prior art, the utility model provides a lens group, wherein the focal length of the lens group is F, and the lens group comprises a first lens, a second lens and a third lens which are coaxially arranged in sequence from the object side to the image side.

[0006] The first lens has positive power, and the focal length f1 of the first lens satisfies: 1.1F≤f1≤1.4F;

[0007] The second lens has negative optical power, and the focal length f2 of the second lens satisfies: 10F≤|f2|≤20F; and

[0008] The third lens has positive focal power, and the focal length f3 of the third lens satisfies: 6F≤f3≤16F;

[0009] The lens assembly also includes:

[0010] a partial reflection device, wherein the partial reflection device is disposed on a side of the first lens away from the second lens; and

[0011] A reflective polarization device is disposed between the second lens and the third lens.

[0012] According to one aspect of the utility model, the lens assembly further includes:

[0013] A phase retarder is disposed between the second lens and the reflective polarizer, and is configured to change the polarization direction of the light beam incident on the reflective polarizer so as to cause the light beam incident on the reflective polarizer to be reflected or transmitted.

[0014] According to one aspect of the utility model, the partial reflection device is arranged on the surface of the first lens away from the second lens, the phase retarder is arranged on the surface of the second lens, and the reflection polarization device is arranged on the surface of the phase retarder away from the second lens.

[0015] According to one aspect of the utility model, the surface of the second lens close to the first lens is a concave surface, and the surface of the second lens close to the third lens is a plane or a concave surface.

[0016] According to one aspect of the utility model, the partial reflection device is a semi-transmissive and semi-reflective film, the reflective polarization device is a reflective polarizer, and the phase retarder is a quarter-wave plate.

[0017] According to one aspect of the utility model, the lens assembly further includes:

[0018] A phase adjustment device is disposed on a side of the partial reflection device away from the first lens, and is configured to receive incident light and adjust the incident light to circularly polarized light before emitting it toward the partial reflection device.

[0019] According to one aspect of the utility model, the focal length f1 of the first lens, the focal length f2 of the second lens and the focal length f3 of the third lens satisfy:

[0020] 0.3<|f2+f1| / |f2-f1|<1.5;

[0021] 1.1<|f1+f3| / |f1-f3|<2.

[0022] According to one aspect of the utility model, the cross-sectional diameter of the first lens perpendicular to the optical axis is R1; the cross-sectional diameter of the second lens perpendicular to the optical axis is R2; the cross-sectional diameter of the third lens perpendicular to the optical axis is R3; the lens group satisfies:

[0023] 0.4<F / R3<0.55;

[0024] 0.416<F / R2<0.44;

[0025] 0.416<F / R1<0.42.

[0026] According to one aspect of the utility model, the refractive index of the first lens is n1, the Abbe number is vd1, the refractive index of the first lens satisfies: 1.4<n1<1.56, and the Abbe number of the first lens satisfies: 55<vd1<70;

[0027] The refractive index of the second lens is n2, and the Abbe number is vd2. The refractive index of the second lens satisfies: 1.7<n2<1.96, and the Abbe number of the second lens satisfies: 17<vd2<30.

[0028] According to one aspect of the present invention, the focal length f1 of the first lens, the focal length f2 of the second lens and the focal length f3 of the third lens satisfy: 20F≤|f3 / F|+|f2 / F|+|f1 / F|≤50F.

[0029] According to one aspect of the present invention, the field of view angle of the lens group is greater than or equal to 120°.

[0030] According to one aspect of the utility model, when the wavelength of the incident light is in the range of 480nm-650nm, the vertical axis chromatic aberration range of the lens group is 0-90μm, and the circumferential chromatic aberration range of the lens group is 1-7μm; when the incident light is mixed light, the wave aberration of the lens group is less than or equal to ten times the wavelength, and when the incident light is a single wavelength light, the wave aberration of the lens group is less than or equal to one times the wavelength.

[0031] According to one aspect of the utility model, the lens group further includes a fourth lens, and the fourth lens is arranged between the first lens and the second lens, or between the reflective polarization device and the third lens.

[0032] According to one aspect of the utility model, an embodiment of the utility model further includes an optical module for a near-eye display device, the optical module comprising:

[0033] A lens assembly as previously described; and

[0034] A display screen is arranged on a side of the partial reflective device in the lens group away from the first lens, and the display screen is perpendicular to the optical axis of the lens group.

[0035] According to one aspect of the present utility model, an embodiment of the present utility model further includes a near-eye display device, the near-eye display device comprising:

[0036] Housing; and

[0037] At least one optical module as described above, wherein the optical module is encapsulated in the housing.

[0038] Compared with the prior art, an embodiment of the utility model provides a lens group, including a first lens, a second lens and a third lens arranged coaxially. By constraining the size relationship between the focal lengths of the first lens, the second lens and the third lens and the focal length F of the lens group, it is beneficial to improve the clarity of the imaging of the lens group and enhance the light effect of the signal light. The utility model is suitable for near-eye display devices, and can improve the field of view of the near-eye display devices while reducing chromatic aberration.

[0039] Embodiments of the utility model also include an optical module and a near-eye display device for a near-eye display device. By applying the aforementioned lens group, the clarity of the near-eye display device can be improved, and a large field of view can be provided for the near-eye display device, while reducing the impact of chromatic aberration on imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0041] Figure 1 It is a structural schematic diagram of a lens group in one embodiment of the utility model;

[0042] Figure 2 is a schematic diagram of the optical path of a lens group in one embodiment of the utility model;

[0043] Figure 3 is a schematic diagram of vertical axis chromatic aberration of a lens assembly in one embodiment of the utility model;

[0044] Figure 4 is a schematic diagram of the MTF (Modulation Transfer Function) of a lens group in one embodiment of the utility model;

[0045] Figure 5 It is a schematic diagram of field curvature and distortion of a lens group in one embodiment of the utility model;

[0046] Fig. 6A It is a dot pattern of the lens group in the wavelength range of 480nm-650nm in one embodiment of the utility model;

[0047] Figure 6B It is a dot matrix diagram of a lens group in one embodiment of the utility model at a wavelength of 550nm;

[0048] Figure 7 is an optical path difference diagram of a lens group in one embodiment of the utility model;

[0049] Figure 8 is a schematic diagram of the RMS wave difference of a lens group in one embodiment of the utility model;

[0050] Fig. 9 is a schematic diagram of vertical axis chromatic aberration of a lens assembly in another embodiment of the present invention;

[0051] Fig.10 is a schematic diagram of the MTF of a lens group in another embodiment of the present invention;

[0052] Fig.11 is a schematic diagram of the optical path difference of a lens group in another embodiment of the utility model;

[0053] Fig. 12A and Fig. 12B It is a schematic diagram of the structure of the lens group in different embodiments of the utility model;

[0054] Fig.13 It is a structural schematic diagram of an optical module in one embodiment of the utility model;

[0055] Fig.14 is a schematic diagram of a near-eye display device in one embodiment of the present invention. DETAILED DESCRIPTION

[0056] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0057] In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "plurality" means two or more than two, unless otherwise clearly and specifically defined.

[0058] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0059] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is lower in level than the second feature.

[0060] The disclosure below provides many different embodiments or examples for realizing different structures of the utility model. In order to simplify the disclosure of the utility model, the components and settings of specific examples are described below. Of course, they are merely examples, and the purpose is not to limit the utility model. In addition, the utility model may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the utility model provides various specific examples of processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0061] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0062] Figure 1 The structure of the lens group 1 according to one embodiment of the utility model is shown. Figure 2 The optical path of the lens group 1 according to an embodiment of the utility model is shown below. Figure 1 and Figure 2 The lens group 1 will be described.

[0063] The lens group 1 includes a first lens 11, a second lens 12, and a third lens 13 which are coaxially arranged in sequence from the object side to the image side, wherein the first lens 11 has positive optical power, and the focal length f1 of the first lens 11 satisfies: 1.1F≤f1≤1.4F. The second lens has negative optical power, and the focal length f2 of the second lens satisfies: 10F≤|f2|≤20F. The third lens has positive optical power, and the focal length f3 of the third lens satisfies: 6F≤f3≤16F.

[0064] like Figure 1 As shown, the lens group 1 further includes a partial reflection device 14 and a reflection polarization device 15 , wherein the partial reflection device 14 is arranged on a side of the first lens 11 away from the second lens 12 , and the reflection polarization device 15 is arranged between the second lens 12 and the third lens 13 .

[0065] The partial reflective device 14 can make part of the incident light transmit and part of the incident light reflect, and is preferably a semi-reflective and semi-transparent film, and the ratio of the incident light transmitted and reflected on the semi-reflective and semi-transparent film is approximately 1:1. The reflective polarizer 15 can control the incident light to reflect or transmit according to the polarization direction of the incident light, and the reflective polarizer 15 is preferably a reflective polarizer. When the polarization direction of the incident light is parallel to the direction of the light transmission axis of the reflective polarizer, the incident light is transmitted at the reflective polarizer, and when the polarization direction of the incident light is not parallel to the direction of the light transmission axis of the reflective polarizer, the incident light is reflected at the reflective polarizer. According to a preferred embodiment of the utility model, the partial reflective device 14 can be arranged on a side of the first lens 11 away from the second lens 12, for example, attached, and the reflective polarizer 15 is arranged on a side of the second lens 12 facing the third lens 13, for example, attached, so as to further simplify the structure of the lens group 1 and reduce the size of the lens group 1.

[0066] In the lens group 1, the focal lengths of the first lens 11, the second lens 12 and the third lens 13 are constrained, and the incident light is deflected by the first lens 11, the second lens 12 and the third lens 13 to finally form the desired output light. For the lens group 1 applied to the near-eye display device, the output light is usually focused on the position of the human eye, and the distance between the lens group 1 and the human eye is related to the shell structure of the near-eye display device. Figure 2 The optical path of the lens group 1 in this embodiment is described.

[0067] like Figure 2As shown, the incident light is incident from the side of the first lens 11 away from the second lens 12. The incident light can pass through the partial reflector 14 and enter the first lens 11. The first lens 11 has a positive focal length and converges the incident light before entering the second lens 12. The second lens 12 has a negative focal length and diverges the incident light. After the incident light passes through the second lens 12 and exits, it is reflected at the reflective polarizer 15. After passing through the second lens 12 and the first lens 11 for the second time, it is reflected at the partial reflector 14. After passing through the first lens 11 and the second lens 12 for the third time, it is transmitted at the reflective polarizer 15, refracted by the third lens 13, and converged again before exiting toward the human eye.

[0068] In this embodiment, a partial reflection device 14 and a reflection polarization device 15 are used to fold the optical path of the incident light, so that the incident light undergoes multiple refractions, thereby extending the optical path of the incident light and reducing the number of optical elements, which is beneficial to reducing the size and weight of the near-eye display device and can also save the production cost of the near-eye display device.

[0069] In this embodiment, the relationship between the focal length f1 of the first lens 11, the focal length f2 of the second lens 12, and the focal length f3 of the third lens 13 and the focal length F of the lens group 1 is constrained, which can provide a larger field of view for the lens group 1, reduce vertical axis dispersion, and improve imaging clarity, which will be described in conjunction with specific parameters in the subsequent embodiments. In addition, in this embodiment, the material selection of the first lens 11, the second lens 12, and the third lens 13 is more abundant, not limited to injection molded lenses, and glass lenses can also be selected. The refractive indexes of the first lens 11, the second lens 12, and the third lens 13 can be different, which can further optimize the field of view and improve the imaging clarity.

[0070] In a preferred embodiment of the present invention, Figure 1 As shown, the lens group 1 further includes a phase retarder 16, which is disposed between the second lens 12 and the reflective polarizer 15. The phase retarder 16 is configured to change the polarization direction of the light beam incident on the reflective polarizer 15, so that the light beam incident on the reflective polarizer 15 is reflected or transmitted. Preferably, the phase retarder 16 is disposed on the surface of the second lens 12, and the reflective polarizer 15 is disposed on the surface of the phase retarder 16. For example, the phase retarder 16 and the reflective polarizer 15 are films, which are sequentially attached to the side of the second lens 12 facing the third lens 13.

[0071] The phase retarder 16 can change the polarization direction of the incident light. For example, the phase retarder 16 is a quarter wave plate, which has different propagation speeds for light with different polarization directions, so that the incident light with some polarization directions is delayed. In the optical path of the aforementioned embodiment, the incident light is mainly reflected when it is incident on the reflective polarizer 15 for the first time, and is mainly transmitted when the reflective polarizer 15 is set for the second time. Preferably, the phase retarder 16 can be configured to make the polarization direction of the light beam incident on the reflective polarizer 15 for the first time perpendicular to the light transmission axis of the reflective polarizer 15, so that the incident light is reflected at the reflective polarizer 15. The light beam reflected from the reflective polarizer 15 passes through the phase retarder 16 again, for example, a phase delay of 1 / 4π is generated. When the light beam is reflected at the partial reflective device 14 and passes through the phase retarder 16 there, a phase delay of 1 / 4π is generated again, that is, the polarization direction is deflected by 90°, and the polarization direction of the light beam incident on the reflective polarizer 15 is parallel to the light transmission axis of the reflective polarizer 15, and can be transmitted at the reflective polarizer 15.

[0072] like Figure 1 As shown, according to a preferred embodiment of the present invention, the lens assembly 1 further includes a phase adjustment device 17, which is arranged on a side of the partial reflector 14 away from the first lens 11. The phase adjustment device 17 is, for example, a sheet-shaped optical structure. The phase adjustment device 17 is arranged to receive incident light and adjust the incident light to circular polarization and then emit it toward the partial reflector 14. In practical applications, the lens assembly 1 can be arranged to cooperate with a display screen ( Figure 1 and Figure 2 The phase adjustment device 17 can be configured to convert the light beam emitted by the display screen into circularly polarized light to cooperate with the reflective polarization device 15. Of course, in other embodiments of the present invention, the display screen (light source) can also be configured to emit circularly polarized light. In this case, the phase adjustment device 17 does not need to be provided.

[0073] According to a preferred embodiment of the present utility model, Figure 1 and Figure 2As shown, the surface of the second lens 12 close to the first lens 11 is a concave surface, and the surface of the second lens 12 close to the third lens 13 is a plane or a concave surface. In this embodiment, the second lens 12 has a negative focal length, and the first lens 11 and the third lens 13 both have positive focal lengths, that is, the first lens 11 and the third lens 13 both have convex surfaces, and the utility model constrains the focal lengths of the first lens 11, the second lens 12, and the third lens 13, and sets the surface of the second lens 12 close to the first lens 11 and the surface close to the third lens 13 to be concave surfaces, which is conducive to further reducing the size of the lens group 1 along the optical axis. Setting the surface of the second lens 12 close to the third lens 13 to a plane is conducive to setting a phase retarder 16 and a reflective polarizer 15 on the surface of the second lens 12.

[0074] By adjusting the design parameters of each element in the lens group 1, the field of view of the lens group 1 can be set to be greater than or equal to 120°. Under a large field of view, when the wavelength of the incident light is 480nm-650nm (the main working wavelength of the near-eye display device), the embodiment of the utility model can also reduce chromatic aberration, and control the vertical axis chromatic aberration of the lens group 1 to 0-90μm, and the circumferential chromatic aberration to 1-7μm. At the same time, the embodiment of the utility model can also reduce wave aberration. When the incident light is mixed light, the wave aberration of the lens group 1 is equal to ten times the wavelength. When the incident light is a single wavelength of light, the wave aberration of the lens group 1 is less than or equal to one wavelength.

[0075] In a preferred embodiment of the present invention, the focal length f1 of the first lens 11, the focal length f2 of the second lens 12, and the focal length f3 of the third lens 13 satisfy:

[0076] 0.3<|f2+f1| / |f2-f1|<1.5;

[0077] 1.1<|f1+f3| / |f1-f3|<2, so as to further optimize the focal lengths of the first lens 11, the second lens 12 and the third lens 13 in the lens group 1.

[0078] In a preferred embodiment of the present utility model, the cross-sectional diameter of the first lens 11 perpendicular to the optical axis is R1; the cross-sectional diameter of the second lens 12 perpendicular to the optical axis is R2; the cross-sectional diameter of the third lens 13 perpendicular to the optical axis is R3; the lens group 1 satisfies:

[0079] 0.4<F / R3<0.55;

[0080] 0.416<F / R2<0.44;

[0081] 0.416<F / R1<0.42, so as to allocate the sizes of the first lens 11, the second lens 12 and the third lens 13, and cooperate with the constraints of the focal lengths of the first lens 11, the second lens 12 and the third lens 13, which is beneficial to control the overall structure and size of the lens group 1.

[0082] In a preferred embodiment of the present invention, the refractive index of the first lens 11 is n1, the Abbe number is vd1, the refractive index of the first lens 11 satisfies: 1.4<n1<1.56, and the Abbe number of the first lens 11 satisfies: 55<vd1<70;

[0083] The refractive index of the second lens 12 is n2, and the Abbe number is vd2. The refractive index of the second lens 12 satisfies: 1.7<n2<1.96, and the Abbe number of the second lens 12 satisfies: 17<vd2<30.

[0084] In a preferred embodiment of the present invention, the focal length f1 of the first lens 11, the focal length f2 of the second lens 12 and the focal length f3 of the third lens 13 satisfy: 20F≤|f3 / F|+|f2 / F|+|f1 / F|≤50F.

[0085] The above constraints are all preferred embodiments of the present invention. In different embodiments of the present invention, the optical parameters of the first lens 11, the second lens 12 and the third lens 13 of the present invention can be combined with each other without conflicting with each other. The lens group 1 is described below in conjunction with specific embodiments.

[0086] In a specific embodiment of the present invention, the parameters of the lens group 1 for magnified imaging are analyzed by reverse modeling design based on the principle of reversible propagation of light. The design parameters of the lens group 1 are shown in Table 1 below.

[0087] Table 1:

[0088]

[0089]

[0090] In Table 1, the distances between the surfaces represented by numbers 0-9 and the light source gradually decrease as the numbers increase, and number 9 represents the surface of the first lens 11 that is away from the second lens 12. The surface numbered 0 actually represents the design parameters related to the virtual imaging surface, and numbered 1 represents the aperture, which is used to replace the design parameters of the human eye observation distance position (the surface type is the paraxial surface PARAXIAL), and the aperture of the aperture in this embodiment is 4 mm.

[0091] Serial numbers 2 and 3 represent the surface of the third lens 13 away from the second lens 12 and the surface close to the second lens 12, respectively. Both surfaces are even-order aspherical surfaces. The material of the third lens 13 is H-ZLAF69 (optical glass brand).

[0092] Serial number 4 represents the reflective polarizer 15. The reflective polarizer 15 is a film with a surface type of STANDARD standard surface and a diameter of 64 mm. In this embodiment, the refractive index of the reflective polarizer 15 is 1.52. For example, the material of the reflective polarizer 15 is BK7 (borosilicate crown glass grade).

[0093] Serial number 5 represents the phase retarder 16, which is a membrane with a surface type of STANDARD standard surface and a diameter of 64 mm. In this embodiment, the refractive index of the phase retarder 16 is 1.49. For example, the material of the phase retarder 16 is PMMA (polymethyl methacrylate).

[0094] Serial number 6 indicates a surface of the second lens 12 close to the third lens 13 , wherein the surface type of the second lens 12 close to the third lens 13 is a STANDARD standard surface, and the surface of the second lens 12 close to the third lens 13 is a plane with an infinite curvature radius.

[0095] Serial number 7 indicates the surface of the second lens 12 away from the third lens 13, and the surface of the second lens 12 away from the third lens 13 is an even-order non-plane. The material of the second lens 12 is H-ZF73 (optical glass brand), and the diameter is 64 mm.

[0096] Serial numbers 8 and 9 respectively represent the design parameters of the two surfaces of the first lens 11, both of which are aspherical surfaces. The material of the first lens 11 is APL5014XH (cycloolefin copolymer produced by Mitsui, Japan), and the diameter is 64 mm. The relationship between the focal length f of the reflection surface of the partial reflection device 14 and the focal length F of the lens group 1 is f=1.47F.

[0097] Serial number 10 indicates the surface of the first lens 11 close to the second lens 12; Serial number 11 indicates the surface of the second lens 12 close to the first lens 11; Serial number 12 indicates the phase retarder 16 (the surface of the second lens 12 close to the third lens 13 is omitted); Serial number 13 indicates the reflective polarizer 15; Serial number 14 indicates the surface of the second lens 12 close to the third lens 13 (the phase retarder 16 is omitted); Serial number 15 indicates the surface of the second lens 12 close to the first lens 11; Serial number 16 indicates the surface of the first lens 11 close to the second lens 12; Serial number 17 indicates the surface of the first lens 11 away from the second lens 12. Serial numbers 10-17 have the same design parameters as the corresponding surfaces above, and are not repeated one by one.

[0098] Serial number 18 indicates a protective panel for the phase adjustment device 17 and the light source (display screen), the surface type is STANDARD standard surface, and the material is BK7.

[0099] Serial number 19 represents the actual object plane of the light source (display screen).

[0100] The even-order aspheric surface in the above table can be calculated by the following formula:

[0101]

[0102] In the above formula, r represents the distance from the point on the lens to the optical axis, c represents the curvature of the vertex of the surface, k represents the quadratic surface coefficient, α1, α2, α3, α4, α5, α6, α7 and α8 represent the 2nd, 4th, 6th, 8th, 10th, 12th, 14th and 16th surface coefficients respectively.

[0103] For example, the surface of the third lens 13 indicated by number 2 in Table 1 that is away from the second lens 12 is an even-order aspheric surface, which can be determined by the above formula: c = -1 / 212.77, k = -262.5174, α1 = 0, α2 = 2.3697E-06, α3 = -5.5001E-09, α4 = 2.1224E-12, α5 = 0, α6 = 0, α7 = α8 = 0. Substituting the above values ​​into the above formula, the aspheric expression of the surface of the third lens 13 that is away from the second lens 12 can be obtained. The same is true for other even-order aspheric surfaces in the lens group 1, and the aspheric expressions can be determined specifically according to the following Table 2.

[0104] Table 2:

[0105] Serial number Surface type Cone coefficient 2nd order terms 4th-order term 6th order term 8th order term 10th order term 0 STANDARD 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 1 PARAXIAL 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 2 EVENASPH -2.63E+02 0.00E+00 2.37E-06 -5.50E-09 2.12E-12 0.00E+00 3 EVENASPH -2.08E+39 0.00E+00 -3.73E-06 -1.62E-09 0.00E+00 0.00E+00 4 STANDARD 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 5 STANDARD 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 6 STANDARD 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 7 EVENASPH 1.86E+00 0.00E+00 5.11E-07 0.00E+00 0.00E+00 0.00E+00 8 EVENASPH -1.90E+01 0.00E+00 -2.62E-06 2.52E-09 -8.70E-13 0.00E+00 9 EVENASPH -7.79E+00 0.00E+00 -1.64E-06 1.16E-09 -3.00E-13 -8.77E-17 10 EVENASPH -1.90E+01 0.00E+00 -2.62E-06 2.52E-09 -8.70E-13 0.00E+00 11 EVENASPH 1.86E+00 0.00E+00 5.11E-07 0.00E+00 0.00E+00 0.00E+00 12 STANDARD 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 13 STANDARD 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 14 STANDARD 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 15 EVENASPH 1.86E+00 0.00E+00 5.11E-07 0.00E+00 0.00E+00 0.00E+00 16 EVENASPH -1.90E+01 0.00E+00 -2.62E-06 2.52E-09 -8.70E-13 0.00E+00 17 EVENASPH -7.79E+00 0.00E+00 -1.64E-06 1.16E-09 -3.00E-13 -8.77E-17 18 STANDARD 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 19 STANDARD 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

[0106] The serial numbers in Table 2 correspond to the serial numbers in Table 1. Table 2 records the surface coefficients of the 2nd-order term, 4th-order term, 6th-order term, 8th-order term and 10th-order term of the aspheric surface.

[0107] The vertical axis chromatic aberration curve of the lens group 1 in this embodiment is as follows: Figure 3 As shown by Figure 3 It can be seen that when the wavelength of the incident light of the lens group 1 in this embodiment is within the range of 480nm-650nm (the main wavelength range used in near-eye display devices), within the maximum half field of view of 60° (full field of view of 120°), the 480nm blue light and the 650nm red light deviate from the vertical axis chromatic aberration range of 0-46μm of the designed main wavelength of 550nm, that is, the lens group 1 in this embodiment can maintain a low vertical axis chromatic aberration within a large field of view of 120°, thereby improving the accuracy of imaging.

[0108] The lens group 1 in this embodiment is applied to a near-eye display device, and the design parameters of the lens group 1 are shown in Table 3 below.

[0109] Table 3:

[0110] Virtual image distance-VID(mm) -2000 Display screen size C (inches) 2.67 Wavelength range (nm) 470-700 Single-eye screen resolution (pixel) 7680*7680 Lens group 1 thickness (mm) 29.2 Field of view FOV(°) 120 The partial reflection device 14 has a reflection focal length f 1.47F Eyebox-eye movement range 11 Lens group 1 focal length F (mm) 26.55 Eye relief-eye distance (mm) 12 F# - Aperture 6.52 Optical outer diameter D(mm) 65 Distortion of lens group 1 -47.00％

[0111] According to Tables 1 to 3, the lens group 1 in this embodiment is a three-piece structure, the focal length F of the lens group 1 is 26.55, the field of view FOV is 120°, and the thickness (length in the optical axis direction) of the lens group 1 is 29.2 mm. The relationship between the focal length f1 of the first lens 11 and the focal length F of the lens group 1 is f1=1.27F, and the relationship between the focal length f of the reflection surface of the partial reflection device 14 and the focal length F of the lens group 1 is f=1.47F.

[0112] When the lens group 1 is applied to a near-eye display device, the aperture of the third lens 13 on the side away from the second lens 12 can be designed to be 6.52, and the corresponding aperture diameter D is 4 mm, and an eye movement range of 11 mm can be obtained. At the same time, the size of the display screen in the near-eye display device can be designed to be 2.67 inches and the eye distance is 12 mm.

[0113] Figure 4 The MTF curve of the lens group 1 in this embodiment is shown in FIG. Figure 4 It can be seen that at a full field of view of 120°, the MTF is 80lp / mm>0.40.

[0114] Figure 5 The field curvature and distortion curves of the lens group 1 in this embodiment are shown. Figure 5 It can be seen that within the full field of view of 120°, the field curvature of the image plane is less than 0.5, and the distortion is less than 46.95%.

[0115] Fig. 6A and Figure 6B FIG. 1 shows a dot matrix diagram of the lens group 1 in the present embodiment under a field of view of 120°, wherein within the wavelength range of 480nm-650nm, as shown in FIG. Fig. 6A As shown, the maximum RMS (scattered spot caused by aberration) radius is less than 32.934μm, and the radius of the Airy (scattered spot caused by the diffraction limit) with a main wavelength of 550nm is 4.474μm. Figure 6B When the incident light is a single light with a wavelength of 550nm, the RMS radius is approximately equal to 0.4 times the Ar iy radius, and the GEO radius (the radius of the smallest central circle containing all light rays with reference points) is approximately equal to the Ar iy radius.

[0116] Figure 7 FIG. 1 shows a schematic diagram of the optical path difference of the lens group 1 in this embodiment. Figure 7It can be seen that within the wavelength range of 480nm-650nm, the maximum optical path difference is within the range of ±10.00 wavelengths.

[0117] Figure 8 FIG. 1 shows a schematic diagram of wave aberration corresponding to the lens group 1 in the embodiment of the present invention at a half field of view of 60°. Figure 8 It can be seen that the diffraction-limited RMS wave aberration is about 0.072. Within the half field of view of 60°, 95% of the wave aberrations are smaller than the diffraction-limited RMS wave aberration. The design parameters of lens group 1 are the optimal solution.

[0118] Combination Figure 4-Figure 8 The simulation test results of the lens group 1 shown in the figure show that the average vertical coordinate MTF of each field of view of the lens group 1 in this embodiment is 80l p / mm, which is greater than the horizontal coordinate (spatial frequency per millimeter) value of 0.40, thereby determining that the viewing angle resolution of the lens group 1 can support a resolution of 7680*7680. In this embodiment, the field curvature and distortion diagram of the lens group 1 are controlled within the range of (-0.5mm, 0.5mm), and the distortion rate is controlled within the range of (-47%, 0).

[0119] According to the above design parameters and simulation test results, the imaging of lens group 1 in this embodiment has high clarity, effectively reduces vertical axis chromatic aberration within a large field of view of 120°, and has small field curvature and distortion, which is suitable for near-eye display devices.

[0120] The utility model also includes another specific embodiment, wherein the optical path of the lens group 1 is as follows Figure 2 As shown, the design parameters of each element in lens group 1 are shown in Table 4 below.

[0121] Table 4:

[0122]

[0123]

[0124] In Table 4, the distances between the surfaces represented by numbers 0-9 and the light source gradually decrease as the numbers increase, and number 9 represents the surface of the first lens 11 away from the second lens 12. The surface numbered 0 actually represents the design parameters related to virtual imaging, and numbered 1 represents the aperture, which is used to replace the design parameters of the human eye observation distance position (the surface type is the paraxial surface PARAXI AL). In this embodiment, the aperture of the aperture is 4 mm.

[0125] Serial numbers 2 and 3 represent a surface of the third lens 13 that is away from the second lens 12 and a surface that is close to the second lens 12, respectively. Both surfaces are even-order aspheric surfaces, and the material of the third lens 13 is H-ZLAF69.

[0126] Serial number 4 indicates a reflective polarizer 15 . The reflective polarizer 15 is a film, the surface type of which is a STANDARD standard surface, and the diameter is 64 mm. In this embodiment, the refractive index of the reflective polarizer 15 is 1.52.

[0127] Serial number 5 indicates a phase retarder 16 , which is a membrane, has a surface type of STANDARD standard surface, and a diameter of 64 mm. In this embodiment, the refractive index of the phase retarder 16 is 1.49.

[0128] Serial number 6 indicates a surface of the second lens 12 close to the third lens 13 , wherein the surface type of the second lens 12 close to the third lens 13 is a STANDARD standard surface, and the surface of the second lens 12 close to the third lens 13 is a plane with an infinite curvature radius.

[0129] The serial number 7 indicates the surface of the second lens 12 which is away from the third lens 13. The surface of the second lens 12 which is away from the third lens 13 is an even-order non-plane. The material of the second lens 12 is H-ZF73, and the diameter is 64 mm.

[0130] Serial numbers 8 and 9 respectively represent the design parameters of two surfaces of the first lens 11, both of which are aspherical surfaces. The material of the first lens 11 is APL5014XH, and the diameter is 64 mm. The relationship between the focal length f of the reflection surface of the partial reflection device 14 and the focal length F of the lens group 1 is f=1.31F.

[0131] Serial number 10 indicates the surface of the first lens 11 close to the second lens 12; Serial number 11 indicates the surface of the second lens 12 close to the first lens 11; Serial number 12 indicates the phase retarder 16 (the surface of the second lens 12 close to the third lens 13 is omitted); Serial number 13 indicates the reflective polarizer 15; Serial number 14 indicates the surface of the second lens 12 close to the third lens 13 (the phase retarder 16 is omitted); Serial number 15 indicates the surface of the second lens 12 close to the first lens 11; Serial number 16 indicates the surface of the first lens 11 close to the second lens 12; Serial number 17 indicates the surface of the first lens 11 away from the second lens 12. Serial numbers 10-17 have the same design parameters as the corresponding surfaces above, and are not repeated one by one.

[0132] Serial number 18 indicates a protective panel for the phase adjustment device 17 and the light source (display screen), the surface type is STANDARD standard surface, and the material is BK7.

[0133] Serial number 19 represents the actual object plane of the light source (display screen).

[0134] The even-order aspheric surface in the above table can be calculated by the following formula:

[0135]

[0136] In the above formula, r represents the distance from the point on the lens to the optical axis, c represents the curvature of the vertex of the surface, k represents the quadratic surface coefficient, α1, α2, α3, α4, α5, α6, α7 and α8 represent the 2nd, 4th, 6th, 8th, 10th, 12th, 14th and 16th surface coefficients respectively.

[0137] For example, the surface of the third lens 13, which is denoted by number 2 in Table 4, which is away from the second lens 12, is an even-order aspheric surface, which can be determined by the above formula: c = -1 / 241.3, k = -2442.72, α1 = 0, α2 = 1.12E-05, α3 = -3.35E-08, α4 = 5.09E-11, α5 = -3.26E-14, α6 = 0, α7 = α8 = 0. Substituting the above values ​​into the above formula, the aspheric surface expression of the surface of the third lens 13 away from the second lens 12 can be obtained. The same is true for other even-order aspheric surfaces in the lens group 1, and the aspheric surface expressions can be determined specifically according to the following Table 5.

[0138] Table 5:

[0139]

[0140]

[0141] Fig. 9 The vertical axis chromatic aberration curve of the lens group 1 in this embodiment is shown. Fig. 9 It can be seen that when the wavelength of the incident light is in the range of 480nm-650nm, the vertical axis chromatic aberration range of 480nm blue light and 650nm red light deviating from the designed main wavelength 550nm within the maximum half field of view of 60 degrees (full field of view of 120 degrees) is between 0-19um. The lens group 1 in this embodiment can achieve a smaller vertical axis chromatic aberration within the field of view of 120°.

[0142] Fig.10 The MTF curve of the lens group 1 in this embodiment is shown in FIG. Fig.10 It can be seen that at a full field of view of 120°, the MTF of lens group 1 is 80l p / mm>0.30.

[0143] Fig.11 FIG. 1 shows a schematic diagram of the optical path difference of the lens group 1 in this embodiment. Fig.10 It can be seen that when the wavelength of the incident light is within the range of 480nm-650nm, the maximum optical path difference of the lens group 1 is within the range of ±5.00 wavelengths.

[0144] The lens group 1 in this embodiment is applied to a near-eye display device, and the design parameters of the lens group 1 are shown in Table 6 below.

[0145] Table 6:

[0146] Virtual Image Distance-VID(mm) -2000 Display screen size C (inches) 2.67 Wavelength range (nm) 470-700 Single-eye screen resolution (pixel) 7680*7680 Lens group 1 thickness (mm) 29.35 Field of view FOV(°) 120 The partial reflection device 14 has a reflection focal length f 1.31F Eyebox-eye movement range 11 Lens group 1 focal length F (mm) 25.55 Eye relief-eye distance (mm) 12.2 F# - Aperture 6.4 Optical outer diameter D(mm) 64 Distortion of lens group 1 -44.70％

[0147] According to Tables 4 to 6, the lens group 1 in this embodiment is a three-piece structure, the focal length F of the lens group 1 is 25.55, the field of view FOV is 120°, and the thickness (length in the optical axis direction) of the lens group 1 is 29.35 mm. The relationship between the focal length f1 of the first lens 11 and the focal length F of the lens group 1 is f1=1.17F, and the relationship between the focal length f of the reflection surface of the partial reflection device 14 and the focal length F of the lens group 1 is f=1.31F.

[0148] When the lens group 1 is applied to a near-eye display device, the aperture of the third lens 13 on the side away from the second lens 12 can be designed to be 6.4, and the corresponding aperture diameter D is 4 mm, and an eye movement range of 11 mm can be obtained accordingly. At the same time, the size of the display screen in the near-eye display device can be designed to be 2.67 inches and the eye distance is 12.2 mm.

[0149] Combination Figure 9-11 The simulation test results of the lens group 1 shown in the figure show that the average ordinate MTF of each field of view of the lens group 1 in this embodiment is 80l p / mm, which is greater than the abscissa (spatial frequency per millimeter) value of 0.30. Therefore, it can be determined that the viewing angle resolution of the lens group 1 can support a resolution of 7680*7680.

[0150] Fig. 12A and Fig. 12B The structure of the lens group 1 according to different embodiments of the present invention is shown, and the lens group 1 further includes a fourth lens 18, which is arranged between the first lens 11 and the second lens 12, or between the reflective polarizer 15 and the third lens 13. The fourth lens 18 can be arranged to have an optical focal length, and can further deflect the incident light, and the design parameters of the fourth lens 18 can be determined according to the actual required output light field.

[0151] like Fig.13 As shown, the embodiment of the utility model further includes an optical module 10 for a near-eye display device, the optical module 10 includes the lens group 1 and the display screen 2 as described in the above embodiment, the display screen 2 is arranged on the side of the partial reflector 14 in the lens group 1 away from the first lens 11, and the display screen is perpendicular to the optical axis of the lens group 1. The display screen 2 can be regarded as a surface light source, which can be controlled to emit a light beam incident on the lens group 1.

[0152] The optical path of the light beam emitted by the display screen 2 is as described in the optical path of the lens group 1 in the above embodiment, and is partially transmitted at the partial reflector 14, and is emitted after being deflected and modulated by the lens group 1. The light beam emitted by the display screen 2 passes through the partial reflector 14 twice. When the partial reflector 14 is a semi-reflective and semi-transmissive film, the absorption of the incident light by other optical elements is not considered, and the utilization rate of the light beam emitted by the display screen 2 is close to 25%.

[0153] like Fig.14 As shown, an embodiment of the present invention further includes a near-eye display device 100 , wherein the near-eye display device 100 includes a housing 20 and at least one optical module 10 as described in the aforementioned embodiment, and the optical module 10 is encapsulated in the housing 20 .

[0154] The housing 20 can be shielded, and the optical module 10 is enclosed in a shielded environment to prevent external light from affecting the imaging of the lens group 1. The inner wall of the housing 20 can also be provided with a light-absorbing material to absorb the light beam irradiated on the inner wall of the housing 20, such as the light beam emitted by the display screen 2 and reflected by the partial reflective device 14, to reduce the stray light incident on the lens group 1. Furthermore, the near-eye display device 100 includes two optical modules 10 as described in the above embodiments, corresponding to the user's eyes respectively.

[0155] Finally, it should be noted that the above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A lens assembly, characterized in that: The focal length of the lens group is F, and the lens group includes a first lens, a second lens and a third lens which are coaxially arranged in sequence from the object side to the image side. The first lens has positive power, and the focal length f1 of the first lens satisfies: 1.1F≤f1≤1.4F; The second lens has negative focal power, and the focal length f2 of the second lens satisfies: 10F≤|f2|≤20F; and The third lens has positive focal power, and the focal length f3 of the third lens satisfies: 6F≤f3≤16F; The lens assembly also includes: A partial reflection device, wherein the partial reflection device is arranged on a side of the first lens away from the second lens; and A reflective polarization device is disposed between the second lens and the third lens.

2. The lens assembly according to claim 1, characterized in that: Also includes: A phase retarder is disposed between the second lens and the reflective polarizer, and is configured to change the polarization direction of the light beam incident on the reflective polarizer so as to cause the light beam incident on the reflective polarizer to be reflected or transmitted.

3. The lens assembly according to claim 2, characterized in that: The partial reflection device is arranged on the surface of the first lens away from the second lens, the phase retarder is arranged on the surface of the second lens, and the reflection polarization device is arranged on the surface of the phase retarder away from the second lens.

4. The lens assembly according to claim 2, characterized in that: The surface of the second lens close to the first lens is a concave surface, and the surface of the second lens close to the third lens is a plane or a concave surface.

5. The lens assembly according to claim 2, characterized in that: The partially reflective device is a semi-transmissive and semi-reflective film, the reflective polarization device is a reflective polarizer, and the phase retarder is a quarter-wave plate.

6. The lens assembly according to any one of claims 2 to 5, characterized in that: Also includes: A phase adjustment device is disposed on a side of the partial reflection device away from the first lens, and is configured to receive incident light and adjust the incident light to circularly polarized light before emitting it toward the partial reflection device.

7. The lens assembly according to any one of claims 1 to 5, characterized in that: The focal length f1 of the first lens, the focal length f2 of the second lens and the focal length f3 of the third lens satisfy: 0.3<|f2+f1| / |f2-f1|<1.5; 1.1<|f1+f3| / |f1-f3|<2.

8. The lens assembly according to any one of claims 1 to 5, characterized in that: The cross-sectional diameter of the first lens perpendicular to the optical axis is R1; the cross-sectional diameter of the second lens perpendicular to the optical axis is R2; the cross-sectional diameter of the third lens perpendicular to the optical axis is R3; the lens group satisfies: 0.4<F / R3<0.55; 0.416<F / R2<0.44; 0.416<F / R1<0.

42.

9. The lens assembly according to any one of claims 1 to 5, characterized in that: The refractive index of the first lens is n1, and the Abbe number is vd1. The refractive index of the first lens satisfies: 1.4<n1<1.56, and the Abbe number of the first lens satisfies: 55<vd1<70; The refractive index of the second lens is n2, and the Abbe number is vd2. The refractive index of the second lens satisfies: 1.7<n2<1.96, and the Abbe number of the second lens satisfies: 17<vd2<30.

10. The lens assembly according to any one of claims 1 to 5, characterized in that: The focal length f1 of the first lens, the focal length f2 of the second lens and the focal length f3 of the third lens satisfy: 20F≤|f3 / F|+|f2 / F|+|f1 / F|≤50F.

11. The lens assembly according to any one of claims 1 to 5, characterized in that: The field of view angle of the lens group is greater than or equal to 120°.

12. The lens assembly according to any one of claims 1 to 5, characterized in that: When the wavelength of the incident light is in the range of 480nm-650nm, the vertical axis chromatic aberration range of the lens group is 0-90μm, and the circumferential chromatic aberration range of the lens group is 1-7μm; when the incident light is mixed light, the wave aberration of the lens group is less than or equal to ten times the wavelength, and when the incident light is a single wavelength, the wave aberration of the lens group is less than or equal to one times the wavelength.

13. The lens assembly according to any one of claims 1 to 5, characterized in that: A fourth lens is also included, and the fourth lens is arranged between the first lens and the second lens, or between the reflective polarization device and the third lens.

14. An optical module for a near-eye display device, characterized in that: include: The lens assembly as claimed in any one of claims 1 to 13; and A display screen is arranged on a side of the partial reflective device in the lens group away from the first lens, and the display screen is perpendicular to the optical axis of the lens group.

15. A near-eye display device, characterized in that: include: shell; and At least one optical module as claimed in claim 14, enclosed in the housing.

Images