Optical Imaging Lens Group, Scanning Display Device, and Near-Eye Display Device

Abstract

Embodiments of the present application disclose an optical imaging lens group, a display device, and a near-eye display device. The optical imaging lens group includes a first lens to a sixth lens arranged coaxially in sequence from a first side to a second side; a first side surface of the first lens is convex, and a second side surface of the first lens is convex; a first side surface of the second lens is concave near the optical axis, and a second side surface of the second lens is convex; a first side surface of the sixth lens is convex, and a second side surface of the sixth lens is concave near the optical axis.

Description

Technical Field

[0001] This application relates to the field of scanning display technology, and particularly relates to an optical imaging lens group, a scanning display device, and a near-eye display device. Background Art

[0002] As an emerging display technology, scanning display imaging can be used in various application scenarios such as projection display and near-eye display.

[0003] Particularly for the application scenario of near-eye display, with the continuous improvement of the requirements for miniaturization, portability, and imaging clarity of near-eye display devices, the demand for high resolution and miniaturization of the optical imaging lens group in near-eye display devices is becoming increasingly stringent. Therefore, providing a miniaturized optical lens group that can be applied to the near-eye display scenario and has high imaging quality has become an urgent problem to be solved in the current industry. Summary of the Invention

[0004] The purpose of this application is to provide an optical imaging lens group, a scanning display device, and a near-eye display device to meet the requirements of high imaging quality and miniaturization in the near-eye display scenario.

[0005] An embodiment of this application provides an optical imaging lens group, which includes a first lens to a sixth lens arranged coaxially in sequence from the first side to the second side. Among them,

[0006] The first side surface of the first lens is a convex surface, and the second side surface of the first lens is a convex surface; the first side surface of the second lens is a concave surface near the optical axis, and the second side surface of the second lens is a convex surface; the first side surface of the sixth lens is a convex surface, and the second side surface of the sixth lens is a concave surface near the optical axis.

[0007] Optionally, the refractive index of the first lens satisfies:

[0008] 1.5 < n1 < 1.7;

[0009] where n1 is the refractive index of the first lens.

[0010] Optionally, the refractive index of the second lens satisfies:

[0011] 1.5 < n2 < 1.8;

[0012] where n2 is the refractive index of the second lens.

[0013] Optionally, the refractive index of the sixth lens satisfies:

[0014] 1.8 < n6 < 2.0;

[0015] where n6 is the refractive index of the sixth lens.

[0016] Optionally, the overall length of the optical imaging lens group is less than or equal to 15 mm.

[0017] Optionally, the overall length of the optical lens group is the maximum length from the first side surface of the first lens to the second side surface of the sixth lens.

[0018] Optionally, the second side of the optical imaging lens group corresponds to a curved surface image.

[0019] In an embodiment of the present application, a scanning display device is further provided, including an optical fiber scanner and the aforementioned optical imaging lens group. The optical fiber scanner is configured to scan and emit light of an image to be displayed, and the optical imaging lens group is configured to magnify and project an image of a scanning surface corresponding to the light emitted by the optical fiber scanner.

[0020] Wherein, the optical fiber scanner includes an actuator and an optical fiber fixed on the actuator. A part of the optical fiber exceeding the actuator forms an optical fiber cantilever, and the optical fiber cantilever performs two-dimensional scanning under the drive of the actuator.

[0021] In an embodiment of the present application, a near-eye display device is further provided, which is used as a head-mounted augmented reality device and at least includes a near-eye display module and the aforementioned scanning display device, and the scanning display device is disposed in the near-eye display module.

[0022] In an embodiment of the present application, a near-eye display device is further provided, which is used as a head-mounted virtual reality device and at least includes a near-eye display module and the aforementioned scanning display device, and the scanning display device is disposed in the near-eye display module

[0023] The technical solutions in the embodiments of the present application can achieve the following technical effects:

[0024] In the embodiments of the present application, by reasonably optimizing the surface shapes and focal lengths of the six coaxial lenses of the optical imaging lens group, the optical power of the system can be reasonably dispersed, the aberration generated by the lenses can be mitigated, and a smaller number of lenses can be used to correct multiple aberrations to achieve clear imaging of the image-side curved surface. At the same time, the overall length of the optical imaging lens group is less than or equal to 15 mm, and the focal length design of the optical imaging lens group can be greater than or equal to 3 mm, which can meet the imaging requirements of higher resolution while realizing the miniaturization of the system. In particular, as an eyepiece, it can be well applied to near-eye display devices with increasing requirements for miniaturization, portability, and imaging clarity.

[0025] Other features and advantages of the present application will be described in the following specification, and part of them will become obvious from the specification, or be understood by implementing the technical solutions of the present application. The objectives and other advantages of the present application can be realized and obtained through the structures and / or processes specifically pointed out in the specification, claims, and drawings. Brief Description of the Drawings

[0026] Other features, objects, and advantages of the present application will become more apparent by reading the following detailed description of non - limiting embodiments with reference to the accompanying drawings:

[0027] Figure 1a 、 1b is a schematic structural diagram of an illustrative scanning display system;

[0028] Figure 2 is a schematic diagram of the scanning output of the fiber optic scanner provided in an embodiment of the present application;

[0029] Figure 3 is a schematic structural diagram of an optical imaging lens group provided in Embodiment 1 of the present application;

[0030] Figure 4 is the MTF curve graph of the optical imaging lens group in Embodiment 1 of the present application;

[0031] Figure 5 is the field curvature and distortion curve graph of the optical imaging lens group in Embodiment 1 of the present application;

[0032] Figure 6 is a schematic structural diagram of another optical imaging lens group provided in Embodiment 2 of the present application;

[0033] Figure 7 is the MTF curve graph of the optical imaging lens group in Embodiment 2 of the present application;

[0034] Figure 8 is the field curvature and distortion curve graph of the optical imaging lens group in Embodiment 2 of the present application. Detailed Description of the Embodiments

[0035] The present application will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention and are not intended to limit the invention. Additionally, it should be noted that for the convenience of description, only parts related to the relevant invention are shown in the drawings.

[0036] Explanatory Scanning Display System

[0037] For current scanning display imaging, it can be implemented by a Digital Micromirror Device (DMD) or a Fiber Scanning Display (FSD) device. Among them, the FSD scheme, as a new type of scanning display imaging method, realizes the scanning output of images through a fiber optic scanner. To enable those skilled in the art to clearly understand the solution of the present application, the brief principle of fiber optic scanning imaging and the corresponding system will be described below.

[0038] As shown Figure 1a in the figure, an illustrative scanning display system in the present application mainly includes:

[0039] a processor 100, a laser group 110, an optical fiber scanning module 120, a transmission optical fiber 130, a light source modulation circuit 140, a scanning drive circuit 150, and a beam combining unit 160. Among them,

[0040] the processor 100 can be a Graphics Processing Unit (GPU), a Central Processing Unit (CPU), or other chips or circuits with control functions and image processing functions, which are not specifically limited here.

[0041] When the system works, the processor 100 can control the light source modulation circuit 140 to modulate the laser group 110 according to the image data to be displayed. The laser group 110 contains multiple monochromatic lasers that emit beams of different colors. As can be seen from Figure 1, specifically, red (R), green (G), and blue (B) lasers can be used in the laser group. The beams emitted by the lasers in the laser group 110 are combined into a single laser beam by the beam combining unit 160 and coupled into the transmission optical fiber 130.

[0042] The processor 100 can also control the scanning drive circuit 150 to drive the optical fiber scanner in the optical fiber scanning module 120 to scan, so as to scan and output the beam transmitted in the transmission optical fiber 130.

[0043] The beam scanned and output by the optical fiber scanner acts on a pixel position on the surface of the medium, and a light spot is formed at this pixel position, thus realizing the scanning of this pixel position. Driven by the optical fiber scanner, the output end of the transmission optical fiber 130 sweeps according to a certain scanning trajectory, so that the beam moves to the corresponding pixel position. During the actual scanning process, the beam transmitted by the transmission optical fiber 130 will form a light spot with corresponding image information (such as color, grayscale, or brightness) at each pixel position. In the time of one frame, the beam traverses each pixel position at a high enough speed to complete the scanning of one frame of image. Due to the characteristic of "visual persistence" when the human eye observes things, the human eye cannot perceive the movement of the beam at each pixel position, but sees a complete frame of image.

[0044] Continue to refer to Figure 1b, which is the specific structure of the fiber optic scanning module 120, including: a scanning actuator 121, a fiber optic cantilever 122, a lens group 123, a scanner package housing 124, and a fixing member 125. The scanning actuator 121 is fixed in the scanner package housing 124 through the fixing member 125. The transmission fiber 130 extends at the front end of the scanning actuator 121 to form a fiber optic cantilever 122 (also referred to as a scanning fiber). During operation, under the drive of a scanning drive signal, the slow axis 121a (also referred to as the first actuation part) of the scanning actuator 121 vibrates in the vertical direction (this vertical direction is parallel to Figure 1a , 1b the Y-axis in the reference coordinate system in, and in this application, this vertical direction can also be referred to as the first direction), and its fast axis 121b (also referred to as the second actuation part) vibrates in the horizontal direction (this horizontal direction is parallel to Figure 1a , 1b the X-axis in the reference coordinate system in, and in this application, this horizontal direction can also be referred to as the second direction). Driven by the scanning actuator 121, the front end of the fiber optic cantilever 122 performs two-dimensional scanning and emits a light beam along a preset trajectory, and the emitted light beam can pass through the lens group 123 to achieve scanning imaging. Generally, the structure composed of the scanning actuator 121 and the fiber optic cantilever 122 can be referred to as: a fiber optic scanner.

[0045] As Figure 2 shown, in the embodiment of this application, through the movement of the fast and slow axes, the movement trajectory of the fiber optic light output end forms a scanning surface 230, and after passing through the corresponding lens group 123, it is converted into an imaging plane 240. When applied to a near-eye display device such as an Augmented Reality (AR) device, the imaging plane 240 will be used as the entrance pupil of the waveguide and coupled into the waveguide for imaging for human eyes to view.

[0046] For the convenience of description and to make it easy for those skilled in the art to understand the solution of this application, it should be noted that the optical imaging lens group in this application (such as Figure 2 the lens group 123 shown in) serves as an eyepiece. Through the action of this optical imaging lens group, the scanning surface 230 can be converted into an imaging plane 240 (in actual application, the light transmission direction is: from the scanning surface 230 to the imaging plane 240). Therefore, on the side of the optical imaging lens group corresponding to the imaging plane 240, it is called the first side, and on the side of the optical imaging lens group corresponding to the scanning surface 230, it is called the second side. In the subsequent content, the "first side" and "second side" will be used as references to describe the embodiment solutions of the optical imaging lens group. And in the subsequent embodiments, the description, such as for a certain lens in the optical imaging lens group, the "first side surface of the Xth lens" refers to the surface of the Xth lens facing the first side.

[0047] Optical Imaging Lens Group

[0048] The optical imaging lens group in the embodiment of the present application includes: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, which are arranged coaxially in sequence from the first side to the second side, with a total of six lenses.

[0049] In a possible implementation manner, there are intervals between the first lens and the second lens, between the second lens and the third lens, and between the fifth lens and the sixth lens, and they are not adhered. That is, the first lens, the second lens, and the sixth lens can be three single non-adhered lenses. The third lens, the fourth lens, and the fifth lens can be adhered or not, specifically depending on the actual application needs, and there is no limitation here.

[0050] The first lens is a biconvex lens, that is, both the first side surface and the second side surface of the first lens are convex surfaces. The refractive index satisfies 1.5 < n1 < 1.7, where n1 is the refractive index of the first lens.

[0051] The first side surface of the second lens is concave near the optical axis, and the second side surface is convex. The refractive index satisfies 1.5 < n2 < 1.8, where n2 is the refractive index of the second lens.

[0052] The first side surface of the sixth lens is convex, and the second side surface is concave near the optical axis. The refractive index satisfies 1.8 < n6 < 2.0, where n6 is the refractive index of the sixth lens.

[0053] For the optical imaging lens group in the embodiment of the present application, when the surface type structures and installation positions of the first lens, the second lens, and the sixth lens are determined, the third lens, the fourth lens, and the fifth lens can be arranged according to the first lens, the second lens, and the sixth lens (parameters such as the surface type, focal length, and refractive index of the third lens, the fourth lens, and the fifth lens will be illustrated in subsequent embodiments), so as to form several different optical imaging lens groups.

[0054] In the embodiment of the present application, the overall length L of the optical imaging lens group ≤ 15 mm. It should be noted here that the overall length of the optical imaging lens group is the maximum length from the first side surface of the first lens to the second side surface of the sixth lens. In some implementation manners, the surface type of the lens is not concave or convex on the entire side surface, and the surface type of the lens may be a composite curved surface, or the near-optical axis part is a curved surface while the edge part is not a curved surface (reference can be made to Figure 3 the sixth lens 16 in

[0055] In the embodiments of the present application, when it is said that the first side surface is a convex surface, it means that the first side surface forms a convex shape in the first side direction towards the optical imaging lens group; when the first side surface is a concave surface, it means that the first side surface forms a concave shape in the first side direction towards the optical imaging lens group; when the second side surface is a convex surface, it means that the second side surface forms a convex shape in the second side direction towards the optical imaging lens group; when the second side surface is a concave surface, it means that the second side surface forms a concave shape in the second side direction towards the optical imaging lens group.

[0056] In the embodiments of the present application, by setting the focal lengths of the lenses in the optical imaging lens group, a total of six lenses, the optical power of the system can be reasonably dispersed, various aberrations can be corrected, and a smaller number of lenses can be used to achieve clear imaging of the image-side curved surface while ensuring a small size.

[0057] Example 1

[0058] Figure 3 This is a schematic structural diagram of an optical imaging lens group provided by an embodiment of the present invention. The optical imaging lens group includes a first lens 11, a second lens 12, a third lens 13, a fourth lens 14, a fifth lens 15, and a sixth lens 16 that are sequentially arranged on the common optical axis from the first side (i.e., the side where the imaging plane 01 is located in Figure 3 to the second side (i.e., the side where the scanning curved surface 02 is located in Figure 3 ).

[0059] In this embodiment, there is a gap between every two adjacent lenses among the first lens 11, the second lens 12, the third lens 13, the fourth lens 14, the fifth lens 15, and the sixth lens 16, and the first lens 11, the second lens 12, the third lens 13, the fourth lens 14, the fifth lens 15, and the sixth lens 16 are six single non-bonded lenses.

[0060] The focal lengths of the first lens 11 to the sixth lens 16 from the first side to the second side are positive, positive, negative, positive, positive, and negative in sequence.

[0061] The first lens 11 is a biconvex lens, that is, both its first side surface and second side surface are convex surfaces.

[0062] The second lens 12 is a positive meniscus lens. The first side surface of the second lens 12 is a concave surface near the optical axis, and the second side surface is a convex surface.

[0063] The first side surface of the third lens 13 is a plane, and the second side surface is a concave surface.

[0064] The first side surface of the fourth lens 14 is a plane, and the second side surface is a convex surface.

[0065] The fifth lens 15 is a biconvex lens.

[0066] The sixth lens 16 is a negative meniscus lens. The first side surface of the sixth lens 16 is convex, and the second side surface is concave near the optical axis.

[0067] In this embodiment, the focal lengths of the first lens 11 to the sixth lens 16 in the optical imaging lens group satisfy the following relational expressions:

[0068] 1.5 < f1 / f < 3,

[0069] 7 < f2 / f < 9,

[0070] 0.5 < |f3 / f| < 1.5,

[0071] 1 < f4 / f < 2,

[0072] 1 < f5 / f < 1.5,

[0073] 1 < |f6 / f| < 1.5,

[0074] Among them, f is the equivalent focal length of the optical imaging lens group, f1 is the focal length of the first lens 11, f2 is the focal length of the second lens 12, f3 is the focal length of the third lens 13, f4 is the focal length of the fourth lens 14, f5 is the focal length of the fifth lens 15, and f6 is the focal length of the sixth lens 16.

[0075] The refractive indices of the first lens 11 to the sixth lens 16 in the optical imaging lens group satisfy the following conditions:

[0076] 1.5 < n1 < 1.7,

[0077] 1.5 < n2 < 1.8,

[0078] 1.85 < n3 < 2.0,

[0079] 1.7 < n4 < 1.9,

[0080] 1.65 < n5 < 1.8,

[0081] 1.8 < n6 < 2.0.

[0082] Among them, n1 to n6 respectively represent the refractive indices of the first lens 11 to the sixth lens 16.

[0083] In the optical imaging lens group provided by the embodiment of the present invention, the material of the lens can be glass, plastic or other materials. Preferably, the lens is made of glass, which can increase the degree of freedom of the refractive power configuration. In this embodiment, the lens in the optical imaging lens group is mainly taken as an example of glass for introduction, and different lenses in the optical imaging lens group can adopt glasses with different refractive indices.

[0084] In this embodiment, the equivalent focal length of the overall optical imaging lens group is 3 mm. The preferred parameters of the curvature radius, thickness, and refractive index of each lens for imaging a scanning curved surface (taking a spherical surface as an example) are shown in Table 1 as follows:

[0085]

[0086] Table 1

[0087] In Table 1, taking the total optical length of the optical imaging lens group, that is, the distance between the imaging plane 01 and the second side surface of the sixth lens 16 as 12.852 mm, and each lens is made of glass and is a spherical lens as an example. The design of the spherical lens is beneficial to the processing of the lens; in practical applications, aspherical lenses can also be used, and their relevant parameters or ratios still satisfy the foregoing content. The optical surface with an infinite curvature radius in the imaging plane 01 refers to a plane.

[0088] Among them, L1 is the distance from the imaging plane 01 to the first side surface of the first lens 11, L2 is the thickness of the first lens 11, and L3 is the distance on the optical axis between the second side surface of the first lens 11 and the first side surface of the second lens 12; L4 is the thickness of the second lens 12, and L5 is the distance on the optical axis between the second side surface of the second lens 12 and the first side surface of the third lens 13; L6 is the thickness of the third lens 13, and L7 is the distance on the optical axis between the second side surface of the third lens 13 and the first side surface of the fourth lens 14; L8 is the thickness of the fourth lens 14, and L9 is the distance on the optical axis between the second side surface of the fourth lens 14 and the first side surface of the fifth lens 15; L10 is the thickness of the fifth lens 15, and L11 is the distance on the optical axis between the second side surface of the fifth lens 15 and the first side surface of the sixth lens 16; L12 is the thickness of the sixth lens 16; L13 is the distance on the optical axis between the second side surface of the sixth lens 16 and the scanning curved surface 02.

[0089] After testing, when the above optical imaging lens group projects the image light corresponding to the scanning surface, its optical transfer function curve is as shown in Figure 4 and the field curvature distortion curve is as shown in Figure 5 shown; among them, the optical transfer function curve (Modulation Transfer Function, MTF) represents the comprehensive resolution level of an optical system, and the field curvature distortion curve represents the F-Tan(theta) distortion magnitude value (percentage) under different field angles.

[0090] From Figure 4 the MTF curve of the optical imaging lens group shown, it can be seen that the MTF at the center is greater than 0.5 at 200 lp / mm, and the MTF at the edge is greater than 0.3 at 200 lp / mm, and the imaging resolution is good within the full field of view. FromFigure 5 It can be seen from the shown field curvature distortion curve that the distortion value of the optical system of the optical imaging lens group is less than 2%, and the distortion is good within the full field of view. Therefore, the optical imaging lens group can clearly image the scanned curved surface image of the fiber scanner, and all have good imaging effects.

[0091] Of course, in practical applications, the optical imaging lens group may further include a photosensitive element, a housing, etc. The photosensitive element can be arranged on the second side of the optical imaging lens group, and the optical imaging lens group can be installed in the housing, so that the curved surface image formed by scanning an image source (such as a fiber scanner) can be imaged on a plane to achieve clear imaging.

[0092] Embodiment 2

[0093] Figure 6 This is a schematic structural diagram of another optical imaging lens group provided by an embodiment of the present invention. The optical imaging lens group includes a first lens 31, a second lens 32, a third lens 33, a fourth lens 34, a fifth lens 35, and a sixth lens 36 that are sequentially arranged on the common optical axis from the first side (i.e., the side where the imaging plane 03 in Figure 6 is located) to the second side (i.e., the side where the scanned curved surface 04 in Figure 6 is located).

[0094] In this embodiment, there is a gap between every two adjacent lenses among the first lens 31, the second lens 32, the third lens 33, and the sixth lens 36, and the first lens 31, the second lens 32, the third lens 33, the fourth lens 34, the fifth lens 35, and the sixth lens 36 are all non-bonded lenses.

[0095] The focal lengths of the first lens 31 to the sixth lens 36 from the first side to the second side are positive, negative, positive, negative, positive, and positive in sequence.

[0096] The first lens 31 is a biconvex lens, that is, both its first side surface and second side surface are convex surfaces.

[0097] The second lens 32 is a negative meniscus lens. The first side surface of the second lens 32 is concave near the optical axis, and the second side surface is convex.

[0098] The first side surface of the third lens 33 is a plane or a convex surface, and the second side surface is a convex surface.

[0099] The first side surface of the fourth lens 34 is a convex surface, and the second side surface is a concave surface.

[0100] The fifth lens 35 is a biconvex lens.

[0101] The sixth lens 36 is a positive meniscus lens. The first side surface of the sixth lens 36 is a convex surface, and the second side surface is concave near the optical axis.

[0102] In this embodiment, the focal lengths of the first lens 31 to the sixth lens 36 in the optical imaging lens group satisfy the following relational expressions:

[0103] 1.5 < f1 / f < 3,

[0104] 8 < |f2 / f| < 20,

[0105] 2 < f3 / f < 3,

[0106] 0.8 < |f4 / f| < 1.5,

[0107] 1 < f5 / f < 1.8,

[0108] 7 < f6 / f < 12,

[0109] Among them, f is the equivalent focal length of the optical imaging lens group, f1 is the focal length of the first lens 31, f2 is the focal length of the second lens 32, f3 is the focal length of the third lens 33, f4 is the focal length of the fourth lens 34, f5 is the focal length of the fifth lens 35, and f6 is the focal length of the sixth lens 36.

[0110] The refractive indices of the first lens 31 to the sixth lens 36 in the optical imaging lens group satisfy the following conditions:

[0111] 1.5 < n1 < 1.7,

[0112] 1.5 < n2 < 1.8,

[0113] 1.6 < n3 < 1.8,

[0114] 1.9 < n4 < 2.0,

[0115] 1.75 < n5 < 1.9,

[0116] 1.8 < n6 < 2.0,

[0117] Among them, n1 to n6 respectively represent the refractive indices of the first lens 31 to the sixth lens 36.

[0118] In the optical imaging lens group provided by the embodiment of the present invention, the material of the lens can be glass, plastic or other materials. Preferably, the lens is made of glass, which can increase the degree of freedom of the refractive power configuration. In this embodiment, the lens in the optical imaging lens group is mainly taken as an example of glass for introduction, and different lenses in the optical imaging lens group can adopt glasses with different refractive indices.

[0119] In this embodiment, the overall equivalent focal length of the optical imaging lens group is 3.13 mm, and the preferred parameters of the curvature radius, thickness parameter and refractive index of each lens for imaging the scanning curved surface (taking the spherical surface as an example) are shown in Table 2:

[0120]

[0121] Table 2

[0122] In Table 2, taking the total optical length of the optical imaging lens group, that is, the distance between the imaging plane 03 and the second side surface of the sixth lens 36, which is 12.319 mm, and each lens is made of glass and is a spherical lens as an example. The design of the spherical lens is beneficial to the processing of the lens; in practical applications, aspherical lenses can also be used, and their relevant parameters or ratios still satisfy the foregoing content. The optical surface with an infinite radius of curvature in the imaging plane 03 refers to a plane surface.

[0123] Among them, L1 is the distance from the imaging plane 03 to the first side surface of the first lens 31, L2 is the thickness of the first lens 31, and L3 is the distance on the optical axis between the second side surface of the first lens 31 and the first side surface of the second lens 32; L4 is the thickness of the second lens 32, and L5 is the distance on the optical axis between the second side surface of the second lens 32 and the first side surface of the third lens 33; L6 is the thickness of the third lens 33, and L7 is the distance on the optical axis between the second side surface of the third lens 33 and the first side surface of the fourth lens 34; L8 is the thickness of the fourth lens 34, and L9 is the distance on the optical axis between the second side surface of the fourth lens 34 and the first side surface of the fifth lens 35; L10 is the thickness of the fifth lens 35, and L11 is the distance on the optical axis between the second side surface of the fifth lens 35 and the first side surface of the sixth lens 36; L12 is the thickness of the sixth lens 36; L13 is the distance on the optical axis between the second side surface of the sixth lens 36 and the scanning curved surface 04.

[0124] After testing, when using the above optical imaging lens group to project the image light corresponding to the scanning surface, its optical transfer function curve is as shown in Figure 7 shown, and the field curvature distortion curve is as shown in Figure 8 shown.

[0125] From Figure 7 the MTF curve of the optical imaging lens group shown, it can be seen that the MTF at the center is greater than 0.6 at 200 lp / mm, and the MTF at the edge is greater than 0.3 at 200 lp / mm, and the imaging resolution is good within the full field of view. From Figure 8 the field curvature distortion curve shown, it can be seen that the distortion value of the optical system of the optical imaging lens group is less than 2%, and the distortion is good within the full field of view. Therefore, the optical imaging lens group can clearly image the scanning surface image of the fiber scanner, and all have good imaging effects.

[0126] Scanning Display Device

[0127] The foregoing optical imaging lens group can cooperate with a fiber scanner (or a corresponding fiber scanning module) to form the scanning display device in the embodiments of the present application (such asFigure 1a , 1b As shown in 1b , the optical imaging lens group is disposed on the light output path of the fiber optic scanner. Among them, the first side of the optical imaging lens group faces the light output direction of the fiber optic scanner. Preferably, the optical imaging lens group is coaxial with the central optical axis of the fiber optic scanner. Of course, the structure and general principle of the fiber optic scanner can be referred to the foregoing Figure 1a , 1b corresponding content, and will not be elaborated here too much.

[0128] Near-Eye Display Device

[0129] In this application, the scanning display device can be further applied to a near-eye display device, and can cooperate with a near-eye display module to form the near-eye display device in the embodiment of this application, and be used as a head-mounted AR device (such as: AR glasses). The scanning display device is disposed in the near-eye display module.

[0130] Among them, the near-eye display module may include: a light source, a processing and control circuit, a wearable frame structure, a waveguide, etc. The image light beam output by the light source enters the scanning display device, and is scanned and output to the optical display lens group by the fiber optic scanner therein. The scanning curved surface of the fiber optic scanner (which can be referred to the scanning curved surface 02 in Figure 3 and the scanning curved surface 04 in Figure 6 ) is converted into an imaging plane (which can be referred to the imaging plane 01 in Figure 3 and the imaging plane 03 in Figure 6 ) after passing through the optical display lens group. This imaging plane is coupled into the waveguide as the entrance pupil plane of the waveguide, and then extended and imaged by the waveguide and coupled out to enter the human eye.

[0131] As another possible implementation manner, the scanning display device can further cooperate with the near-eye display module to form the near-eye display device in the embodiment of this application, and be used as a head-mounted VR device (such as: VR helmet / glasses). The scanning display device is disposed in the near-eye display module.

[0132] The above are only the preferred specific embodiments of this application. Each embodiment is only used to illustrate the technical solution of this application rather than a limitation to this application. Any technical solution that can be obtained by those skilled in the art through logical analysis, reasoning or effective experiments according to the concept of this application should be within the scope of this application.

[0133] In the embodiments of the present application, by reasonably optimizing the surface shapes and focal lengths of six coaxial lenses of the optical imaging lens group, the optical power of the system can be reasonably dispersed, the aberration generated by the lenses can be reduced, and fewer lenses can be used to correct various aberrations to achieve clear imaging of the image-side curved surface. At the same time, the overall length of the optical imaging lens group is less than or equal to 15 mm, and the focal length of the optical imaging lens group is designed to be greater than or equal to 3 mm, which can meet the imaging requirements of high resolution while realizing the miniaturization of the system, and is applicable to near-eye display devices with increasing requirements for miniaturization, portability, and imaging clarity.

[0134] The embodiments in the present application are all described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other, and the differences between each embodiment and other embodiments are emphasized.

[0135] In various embodiments of the present disclosure, the expressions "first", "second", "the first" or "the second" used may modify various components without regard to order and / or importance, but these expressions do not limit the corresponding components. The above expressions are only configured for the purpose of distinguishing an element from other elements. For example, the first lens and the second lens represent different lenses, although both are lenses.

Claims

1. An optical imaging lens group, characterized in that, The optical imaging lens group consists of six lenses, namely, a first lens to a sixth lens, which are arranged coaxially in sequence from a first side to a second side. The first side is the side of the optical imaging lens group corresponding to the imaging plane, and the second side is the side of the optical imaging lens group corresponding to the scanning curved surface formed by an optical fiber scanner. Among them, the first side surface of the first lens is convex, and the second side surface of the first lens is convex; the first side surface of the second lens is concave near the optical axis, and the second side surface of the second lens is convex; the first side surface of the third lens is flat, and the second side surface of the third lens is concave; the first side surface of the fourth lens is flat, and the second side surface of the fourth lens is convex; the fifth lens is a biconvex lens; the first side surface of the sixth lens is convex, and the second side surface of the sixth lens is concave near the optical axis. The first side surfaces and the second side surfaces of the first lens to the sixth lens are all spherical surfaces. The optical powers of the first lens to the sixth lens are positive, positive, negative, positive, positive, negative; or, the first side surface of the first lens is convex, and the second side surface of the first lens is convex; the first side surface of the second lens is concave near the optical axis, and the second side surface of the second lens is convex; the first side surface of the third lens is flat or convex, the second side surface of the third lens is convex, the first side surface of the fourth lens is convex, the second side surface of the fourth lens is concave, the fifth lens is a biconvex lens, the first side surface of the sixth lens is convex, and the second side surface of the sixth lens is concave near the optical axis. The first side surfaces and the second side surfaces of the first lens to the sixth lens are all spherical surfaces. The optical powers of the first lens to the sixth lens are positive, negative, positive, negative, positive, positive.

2. The optical imaging lens group according to claim 1, characterized in that, The refractive index of the first lens satisfies: 1.5<n1<1.7； where n1 is the refractive index of the first lens.

3. The optical imaging lens group according to claim 1, characterized in that, The refractive index of the second lens satisfies: 1.5<n2<1.8； where n2 is the refractive index of the second lens.

4. The optical imaging lens group according to claim 1, characterized in that, The refractive index of the sixth lens satisfies: 1.8<n6<2.0； where n6 is the refractive index of the sixth lens.

5. The optical imaging lens group according to any one of claims 1 to 4, characterized in that The overall length of the optical imaging lens group is less than or equal to 15 mm. The overall length of the optical imaging lens group is the maximum length from the first side surface to the second side surface of the first lens to the sixth lens.

6. A scanning display device, characterized in that, It includes an optical fiber scanner and the optical imaging lens group according to any one of the preceding claims 1 to 5. The optical fiber scanner is used to scan and emit light of an image to be displayed, and the optical imaging lens group is used to magnify and project the scanning surface corresponding to the light emitted by the optical fiber scanner; wherein, the optical fiber scanner includes an actuator and an optical fiber fixed on the actuator. The part of the optical fiber exceeding the actuator forms an optical fiber cantilever, and the optical fiber cantilever performs two-dimensional scanning under the drive of the actuator.

7. A near-eye display device, characterized in that, The near-eye display device is used as a head-mounted augmented reality device, and at least includes a near-eye display module and the scanning display device according to claim 6. The scanning display device is arranged in the near-eye display module.

8. A near-eye display device, characterized in that, The near-eye display device is used as a head-mounted virtual reality device and at least includes a near-eye display module and the scanning display device according to claim 6, and the scanning display device is arranged in the near-eye display module.

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