Optical system

Abstract

The application provides an optical system. The optical system comprises a lens barrel and, arranged in the lens barrel from an eye side to a display side in sequence, a first element group, a second element group and a third element group, the first element group comprising at least a first lens, the second element group comprising at least a second lens, the third element group comprising at least a third lens, a plurality of spacing elements comprising at least a first spacing element and a second spacing element, the first spacing element being located between the first element group and the second element group and at least partially abutting the first element group, the second spacing element being located between the second element group and the third element group and at least partially abutting the second element group, and the effective focal length FG1 of the first element group, the maximum thickness CP1 of the first spacing element and the interval EP12 of the surface of the first spacing element close to the display side and the surface of the second spacing element close to the eye side along the optical axis satisfying 5.8<FG1 / (CP1+EP12)<10.8. The application solves the problem of long overall length of the prior art optical system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical imaging devices, in particular to an optical system. BACKGROUND

[0002] With the continuous development of the field of optical imaging, various optical display devices have entered people's lives. At the same time, with the increasing market demand, various types of optical display devices need to improve their own characteristics to match market demand.

[0003] In the field of virtual reality, AR / VR has ushered in a second opportunity for development. As an entry for human-computer interaction, the VR optical system plays an important role. On the one hand, the imaging quality of the VR optical system needs to meet the resolution requirements of the human eye; on the other hand, the early aspherical or Fresnel lens has more structures and a longer body, so that the user's center of gravity is forward when wearing, and the experience is not good.

[0004] That is, the optical system in the prior art has the problem of relatively long overall length. SUMMARY

[0005] The main purpose of the present application is to provide an optical system to solve the problem of relatively long overall length of the optical system in the prior art.

[0006] In order to achieve the above-mentioned purpose, the present application provides an optical system, comprising a lens barrel and a first element group, a second element group and a third element group arranged in the lens barrel from the eye side to the display side in sequence, the first element group comprising at least a first lens; the second element group comprising at least a second lens; the third element group comprising at least a third lens; the optical system further comprising a plurality of spacer elements, the plurality of spacer elements comprising at least a first spacer element and a second spacer element, the first spacer element being located between the first element group and the second element group and at least partially abutting the first element group, the second spacer element being located between the second element group and the third element group and at least partially abutting the second element group; the effective focal length FG1 of the first element group, the maximum thickness CP1 of the first spacer element and the interval EP12 along the optical axis of the surface of the first spacer element close to the display side and the surface of the second spacer element close to the eye side satisfy: 5.8<FG1 / (CP1+EP12)<10.8.

[0007] Further, the optical system further comprises a reflective polarizing element and a quarter retardation plate, the reflective polarizing element and the quarter retardation plate being combined on the surface of the first lens close to the display side or on the surface of the second lens close to the eye side.

[0008] Further, an outer diameter D1s of the first spacer member on the side surface closer to the eye, an inner diameter d1s of the first spacer member on the side surface closer to the eye, and a central thickness CT2 of the second lens on the optical axis satisfy: 1.4 < (D1s - d1s) / CT2 < 4.9.

[0009] Further, a radius of curvature R1 of the first lens on the side surface closer to the eye, an outer diameter D1m of the first spacer member on the side surface closer to the display, and an inner diameter d1m of the first spacer member on the side surface closer to the display satisfy: 36.6 < |R1| / (D1m - d1m) < 381.8.

[0010] Further, a central thickness CT1 of the first lens on the optical axis, a distance T12 of the side surface closer to the display of the first lens and the side surface closer to the eye of the second lens on the optical axis, a distance EP12 of the side surface closer to the display of the first spacer member and the side surface closer to the eye of the second spacer member on the optical axis, and a central thickness CP2 of the second lens on the optical axis satisfy: 0.4 < (CT1 x T12) / (EP12 x CP2) < 9.9.

[0011] Further, an inner diameter d2s of the second spacer member on the side surface closer to the eye, an outer diameter D2s of the second spacer member on the side surface closer to the eye, and a radius of curvature R2 of the first lens on the side surface closer to the display satisfy: 2.7 < (d2s + D2s) / |R2| < 3.5.

[0012] Further, a central thickness CT1 of the first lens on the optical axis, a central thickness CT2 of the second lens on the optical axis, and a distance EP12 of the side surface closer to the display of the first spacer member and the side surface closer to the eye of the second spacer member on the optical axis satisfy: 1.1 < (CT1 + CT2) / EP12 < 4.8.

[0013] Further, a distance T12 of the side surface closer to the display of the first lens and the side surface closer to the eye of the second lens on the optical axis, a distance T23 of the side surface closer to the display of the second lens and the side surface closer to the eye of the third lens on the optical axis, and a maximum thickness CP2 of the second spacer member satisfy: 1.1 < (T12 + T23) / CP2 < 23.8.

[0014] Further, a radius of curvature R4 of the second lens on the side surface closer to the display, a radius of curvature R5 of the third lens on the side surface closer to the eye, an outer diameter D2s of the second spacer member on the side surface closer to the eye, and an outer diameter D2m of the second spacer member on the side surface closer to the display satisfy: 0.9 < |R4 + R5| / (D2s + D2m) < 50.0.

[0015] Further, a radius of curvature R5 of a surface of the third lens closer to the eye, a radius of curvature R6 of a surface of the third lens closer to the display, an inner diameter d2m of a surface of the second spacer element closer to the display, and an inner diameter d2s of a surface of the second spacer element closer to the eye satisfy: 1.6 < (|R5| + |R6|) / (d2m + d2s) < 5.9.

[0016] Further, a combined focal length FG2 of the second element group, the inner diameter d2s of the surface of the second spacer element closer to the eye, and the inner diameter d2m of the surface of the second spacer element closer to the display satisfy: 0.9 < FG2 / (d2s + d2m) < 97.2.

[0017] Further, the material of the first lens is the same as the material of the third lens.

[0018] The optical system includes a lens barrel and a first element group, a second element group, and a third element group arranged in the lens barrel in order from the eye to the display, the first element group at least including a first lens, the second element group at least including a second lens, and the third element group at least including a third lens. The optical system further includes a plurality of spacer elements, the plurality of spacer elements at least including a first spacer element and a second spacer element, the first spacer element being located between the first element group and the second element group and at least partially abutting the first element group, and the second spacer element being located between the second element group and the third element group and at least partially abutting the second element group. A effective focal length FG1 of the first element group, a maximum thickness CP1 of the first spacer element, and a spacing EP12 between a surface of the first spacer element closer to the display and a surface of the second spacer element closer to the eye along an optical axis satisfy: 5.8 < FG1 / (CP1 + EP12) < 10.8.

[0019] The optical system of the present application is a visual system composed of three lenses. The present application reduces the number of lenses in the optical system, greatly compresses the overall length of the optical system, avoids the situation that the user's center of gravity is forward when wearing the head-mounted device, and improves the user experience. By providing the first spacer element and the second spacer element between the adjacent element groups, and reasonably restricting the effective focal length of the first element group, the maximum thickness of the first spacer element, and the spacing between the first spacer element and the second spacer element, the shape of the first lens can be effectively controlled, the forming difficulty of the first lens is reduced, the straight size is reasonably controlled, the linear profile requirement of the cooperation part of the lens barrel and the spacer element is reduced, the assembly process difficulty of the optical system is reduced, and the yield of the assembly process of the optical system is improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the application and, together with the description, serve to explain the application. In the drawings:

[0021] Figure 1 A dimensioned view of the optical system of an alternative embodiment of the application is shown;

[0022] Figure 2 A schematic view of the optical system of Example One of the application in a first state is shown;

[0023] Figure 3 A schematic view of the optical system of Example One of the application in a second state is shown;

[0024] Figure 4 A schematic view of the optical system of Example One of the application in a third state is shown;

[0025] Figures 5 to 7 Axial chromatic aberration, astigmatism and distortion curves for Example One of the application are shown respectively;

[0026] Figure 8 A schematic view of the optical system of Example Two of the application in a first state is shown;

[0027] Figure 9 A schematic view of the optical system of Example Two of the application in a second state is shown;

[0028] Figure 10 A schematic view of the optical system of Example Two of the application in a third state is shown;

[0029] Figures 11 to 13 Axial chromatic aberration, astigmatism and distortion curves for Example Two of the application are shown respectively;

[0030] Figure 14 A schematic view of the optical system of Example Three of the application in a first state is shown;

[0031] Figure 15 A schematic view of the optical system of Example Three of the application in a second state is shown;

[0032] Figure 16 A schematic view of the optical system of Example Three of the application in a third state is shown;

[0033] Figures 17 to 19 Axial chromatic aberration, astigmatism and distortion curves for Example Three of the application are shown respectively.

[0034] Wherein the above drawings include the following reference numerals:

[0035] P0, barrel. E1, first lens; E2, second lens; E3, third lens; RP, reflective polarizing element; QWP, quarter-wave plate; P1, first spacer element; P2, second spacer element; IMG, image plane; DETAILED DESCRIPTION

[0036] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict, unless otherwise specified. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0037] It should be noted that, unless otherwise specified, all technical and scientific terms used in the present application have the same meanings as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0038] In the present application, unless otherwise specified, the directional words such as "upper", "lower", "top", "bottom" are generally directed to the directions shown in the drawings, or are directed to the vertical, perpendicular or gravity directions of the components themselves; likewise, for the convenience of understanding and description, "inner" and "outer" refer to the inner and outer relative to the contour of the components themselves, but the above directional words are not used to limit the present application.

[0039] It should be noted that, in the present specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, the first lens discussed below can also be referred to as the second lens or the third lens without departing from the teachings of the present application.

[0040] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for the convenience of illustration. Specifically, the shape of the spherical surface or aspherical surface shown in the drawings is shown by way of example. That is, the shape of the spherical surface or aspherical surface is not limited to the shape of the spherical surface or aspherical surface shown in the drawings. The drawings are merely examples and are not drawn strictly to scale.

[0041] In this context, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not specified, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not specified, it means that the lens surface is concave at least in the paraxial region. The judgment of the surface shape in the paraxial region can be based on the judgment method of those skilled in the art, with the R value (R refers to the radius of curvature in the paraxial region, usually refers to the R value on the lens data in the optical software) to judge the convexity and concavity. In terms of the entrance side surface, when the R value is positive, it is determined to be convex, and when the R value is negative, it is determined to be concave; in terms of the exit side surface, when the R value is positive, it is determined to be concave, and when the R value is negative, it is determined to be convex.

[0042] In order to solve the problem of long overall length of the existing optical system, the application provides an optical system.

[0043] As shown in Figures 1 to 19 The optical system comprises a lens barrel and a first element group, a second element group and a third element group arranged in the lens barrel from the eye side to the display side in sequence, the first element group at least comprising a first lens, the second element group at least comprising a second lens, and the third element group at least comprising a third lens, and the optical system further comprises a plurality of spacer elements, the plurality of spacer elements at least comprising a first spacer element and a second spacer element, the first spacer element being located between the first element group and the second element group and at least partially abutting against the first element group, and the second spacer element being located between the second element group and the third element group and at least partially abutting against the second element group, and the effective focal length FG1 of the first element group, the maximum thickness CP1 of the first spacer element and the interval EP12 along the optical axis between the surface of the first spacer element close to the display side and the surface of the second spacer element close to the eye side satisfy the condition: 5.8 < FG1 / (CP1+EP12) < 10.8.

[0044] The optical system of the application is a visual system composed of three lenses, the application reduces the number of lenses in the optical system, greatly compresses the overall length of the optical system, thereby avoiding the situation that the center of gravity of the user is forward when wearing the head-mounted device, and improves the user experience. By providing the first spacer element and the second spacer element between the adjacent element groups, and reasonably restricting the effective focal length of the first element group, the maximum thickness of the first spacer element and the interval between the first spacer element and the second spacer element, the shape of the first lens can be effectively controlled, the forming difficulty of the first lens is reduced, at the same time, the spacer elements are all in abutment with the inner wall surface of the lens barrel, the straight size is reasonably controlled, the linear profile requirement of the cooperation part of the lens barrel and the spacer element is reduced, the assembly process difficulty of the optical system is reduced, and the yield of the assembly process of the optical system is improved.

[0045] Preferably, 5.86 ≤ FG1 / (CP1+EP12) ≤ 10.77.

[0046] In the embodiment, the optical system further comprises a reflective polarizing element and a quarter retardation plate, and the reflective polarizing element and the quarter retardation plate are combined on the surface of the first lens close to the display side or on the surface of the second lens close to the eye side. The reflective polarizing element is located on the side close to the eye side of the quarter retardation plate. By providing the reflective polarizing element and the quarter retardation plate, the light path can be turned, and the overall length of the optical system is compressed to half of the original, thereby moving the center of gravity of the head-mounted device backward and increasing the experience of the consumer.

[0047] In the embodiment, the outer diameter D1s of the first spacer element near the human eye side surface, the inner diameter d1s of the first spacer element near the human eye side surface, and the central thickness CT2 of the second lens on the optical axis satisfy: 1.4 < (D1s-d1s) / CT2 < 4.9. Satisfying the condition, the processability of the second lens is improved under the premise of guaranteeing the system assembly; meanwhile, by controlling the inner diameter and the outer diameter of the first spacer element near the human eye side surface, the support of the lens structure is satisfied while the processability of the second spacer element is guaranteed. Preferably, 1.48 ≤ (D1s-d1s) / CT2 ≤ 4.53.

[0048] In the embodiment, the curvature radius R1 of the first lens near the human eye side surface, the outer diameter D1m of the first spacer element near the display side surface, and the inner diameter d1m of the first spacer element near the display side surface satisfy: 36.6 < |R1| / (D1m-d1m) < 381.8. By controlling the condition, the curvature radius of the first lens near the human eye side surface is limited, which is conducive to reducing the sensitivity of the first lens and thus improving the yield of the assembly; secondly, the inner diameter and the outer diameter of the two side surfaces of the first spacer element can be limited respectively to guarantee the processability. Preferably, 36.63 ≤ |R1| / (D1m-d1m) ≤ 381.75.

[0049] In the embodiment, the central thickness CT1 of the first lens on the optical axis, the distance T12 of the first lens near the display side surface and the second lens near the human eye side surface on the optical axis, the interval EP12 of the first spacer element near the display side surface and the second spacer element near the human eye side surface along the optical axis, and the central thickness CP2 of the second lens on the optical axis satisfy: 0.4 < (CT1×T12) / (EP12×CP2) < 9.9. By controlling the condition, the main improvement is the stray light. Since the light rays of the first lens and the second lens are relatively steep and the thickness of the first spacer element in the middle is relatively large, more stray light will be generated. Therefore, by controlling the central thickness of the second lens on the optical axis and EP12 within a certain range, the reflection of excess light is reduced, and the imaging quality is improved. Preferably, 0.42 ≤ (CT1×T12) / (EP12×CP2) ≤ 9.88.

[0050] In the embodiment, the inner diameter d2s of the second spacer element near the human eye side surface, the outer diameter D2s of the second spacer element near the human eye side surface, and the curvature radius R2 of the first lens near the display side surface satisfy: 2.7 < (d2s+D2s) / |R2| < 3.5. By controlling the condition, the maximum outer shape of the lens barrel can be limited, which is conducive to realizing the compactness of the optical system, and at the same time, the curvature radius of the first lens near the display side surface is controlled, which is conducive to correcting off-axis aberrations and improving the overall image quality of the system. Preferably, 2.79 ≤ (d2s+D2s) / |R2| ≤ 3.44.

[0051] In the embodiment, the central thickness CT1 of the first lens on the optical axis, the central thickness CT2 of the second lens on the optical axis, and the interval EP12 of the surface close to the display side of the first spacer element and the surface close to the human eye side of the second spacer element along the optical axis satisfy: 1.1 < (CT1+CT2) / EP12 < 4.8. By controlling the central thickness of the first lens, the second lens, and EP12, the thickness-to-thinness ratio of the second lens can be ensured, thereby facilitating the molding of the first lens and the second lens. Preferably, 1.13≤(CT1+CT2) / EP12≤4.72.

[0052] In the embodiment, the distance T12 of the surface close to the display side of the first lens and the surface close to the human eye side of the second lens on the optical axis, the distance T23 of the surface close to the display side of the second lens and the surface close to the human eye side of the third lens on the optical axis, and the maximum thickness CP2 of the second spacer element satisfy: 1.1 < (T12+T23) / CP2 < 23.8. By controlling the condition, the central thickness of the lens and the gap between the lenses are effectively controlled, on the one hand, facilitating the molding of each lens, and on the other hand, facilitating the assembly of the lenses. Preferably, 1.14≤(T12+T23) / CP2≤23.70.

[0053] In the embodiment, the radius of curvature R4 of the surface close to the display side of the second lens, the radius of curvature R5 of the surface close to the human eye side of the third lens, the outer diameter D2s of the surface close to the human eye side of the second spacer element, and the outer diameter D2m of the surface close to the display side of the second spacer element satisfy: 0.9 < |R4+R5| / (D2s+D2m) < 50.0. By controlling this condition, the radii of curvature of the second lens and the third lens are limited, which is conducive to reducing the sensitivity of the second lens and the third lens, thereby improving the yield of assembly; secondly, the outer diameters of the two surfaces of the second spacer element can be limited to ensure its processability. Preferably, 1.00≤|R4+R5| / (D2s+D2m)≤49.80.

[0054] In the embodiment, the radius of curvature R5 of the surface close to the human eye side of the third lens, the radius of curvature R6 of the surface close to the display side of the third lens, the inner diameter d2m of the surface close to the display side of the second spacer element, and the inner diameter d2s of the surface close to the human eye side of the second spacer element satisfy: 1.6 < (|R5|+|R6|) / (d2m+d2s) < 5.9. By controlling this condition, the radii of curvature of the two surfaces of the third lens are limited, which is conducive to reducing the sensitivity of the third lens, thereby improving the yield of assembly; secondly, the inner diameters of the two surfaces of the second spacer element can be limited to ensure its processability. Preferably, 1.62≤(|R5|+|R6|) / (d2m+d2s)≤5.88.

[0055] In the embodiment, the combination focal length FG2 of the second element group, the inner diameter d2s of the surface of the second spacer element close to the human eye side, and the inner diameter d2m of the surface of the second spacer element close to the display side satisfy: 0.9 < FG2 / (d2s+d2m) < 97.2. Through the control of the condition, the light path can be effectively controlled, and the problem of too steep light path causing too high sensitivity of the lens can be avoided. By controlling the size range of the inner diameter of the surface of the second spacer element close to the human eye side and the inner diameter of the surface of the second spacer element close to the display side, the excess light can be blocked, which is helpful for the overall improvement of the stray light of the optical system. Preferably, 0.97 ≤ FG2 / (d2s+d2m) ≤ 97.16.

[0056] In the embodiment, the material of the first lens is the same as the material of the third lens. By controlling the materials of the first lens and the third lens to be consistent, the refractive index of the first lens and the third lens can be kept consistent, which is helpful for restricting the material selection of the second lens, reducing the stress of the lens material, and thus improving the polarization efficiency of the optical system.

[0057] Optionally, the optical system described above can further include a protective glass for protecting the photosensitive element located on the image plane.

[0058] The optical system in the present application can adopt multiple lenses, for example, three lenses as described above. In the present application, at least one of the mirror surfaces of each lens is an aspheric mirror surface. The aspheric lens has the characteristic that the curvature continuously changes from the center of the lens to the periphery of the lens. Unlike the spherical lens which has a constant curvature from the center of the lens to the periphery of the lens, the aspheric lens has better curvature radius characteristics, and has the advantages of improving the distortion aberration and improving the astigmatism aberration. After using the aspheric lens, the aberration that occurs during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0059] However, those skilled in the art should understand that the number of lenses constituting the optical system can be changed without departing from the technical solutions claimed in the present application, to obtain the various results and advantages described in the present specification. For example, although the three lenses are described as an example in the embodiments, the optical system is not limited to including three lenses. If necessary, the optical system can also include other numbers of lenses.

[0060] Figure 1 The structure schematic diagram of an optical system of the present application is shown, wherein Figure 1The parameters of D2s, D1s, d2s, d1s, d2m, d1m, D1m, D2m, CT1, T12, CT2, T13, CT3, CP1, CP2, EP12, and the like are indicated in the figure to clearly and intuitively understand the meaning of the parameters. In order to facilitate the optical system and the specific surface shape, the parameters are not reflected in the figure when the specific examples are described subsequently.

[0061] As shown in Figures 1 to 19 , the optical system includes a lens barrel and a first element group, a second element group, and a third element group arranged in the lens barrel in order from the eye side to the display side, the first element group includes a first lens, the second element group includes a second lens, and the third element group includes a third lens. The optical system further includes a reflective polarizing element and a quarter retardation plate, the reflective polarizing element and the quarter retardation plate are combined on a surface of the second lens close to the eye side, that is, the reflective polarizing element, the quarter retardation plate, and the surface of the second lens close to the eye side are equivalent to an integral. As shown in Figure 1 , the black arrow is the light transmission direction, the left side is the eye side, and the right side is the display side, that is, the STO is the eye side, and the IMG is the display side, which is also the image surface; the light on the display side passes through the third lens, the second lens in turn, and then is incident on the interface of the reflective polarizing element and the quarter retardation plate, and then is reflected for the first time, the light reflected for the first time is transmitted toward the display side, and then is transmitted to the surface of the third lens close to the display side, and is reflected for the second time, the light reflected for the second time passes through the second lens, the quarter retardation plate, the reflective polarizing element, and the first lens in turn to form an image on the eye side.

[0062] The specific surface shape and parameters of the optical system applicable to the above embodiments are further described below with reference to the accompanying drawings.

[0063] It should be noted that in the following examples, there are first, second, and third states, and the curvature radii, center thicknesses, and the like of the first to third lenses of the optical system in the first, second, and third states in the same example are the same, but the thicknesses, inner diameters, and outer diameters of the lens barrel, the first and second spacing elements, and the like and the shapes of some lenses are different. Or, the main structure for imaging is the same, and the auxiliary structure for imaging is different.

[0064] It should be noted that any one of the following examples one to three is applicable to all embodiments of the present application.

[0065] Example One

[0066] As shown in Figures 2 to 7 , the optical system of example one is described. Figure 2A schematic diagram of the optical system in Example 1 in its first state is shown. Figure 3 A schematic diagram of the optical system in Example 1 in the second state is shown. Figure 4 A schematic diagram of the optical system in Example 1 in the third state is shown.

[0067] like Figures 2 to 4 As shown, the optical system includes a lens barrel P0 and a first element group, a second element group, and a third element group sequentially arranged in the lens barrel P0 from the human eye side to the display side along the optical axis of the lens barrel P0. The first element group includes a first lens E1; the second element group includes a second lens E2; and the third element group includes a third lens E3. The optical system also includes a reflective polarizing element RP and a quarter-retarder plate QWP, which are coupled to the surface of the second lens near the human eye side.

[0068] In Example 1, the optical system also includes a first spacer element P1 and a second spacer element P2. The first spacer element P1 is disposed between the first lens E1 and the second lens E2, and the second spacer element P2 is disposed between the second lens E2 and the third lens E3.

[0069] like Figure 2 As shown, in the first state of the optical system, the first spacer element P1 is located between the first lens E1 and the second lens E2. The surface of the first spacer element P1 near the human eye simultaneously and at least partially abuts against the inner wall surface of the lens barrel P0 and the surface of the first lens E1 near the display. The surface of the first spacer element P1 near the display also at least partially abuts against the surface of the second lens E2 near the human eye. The outer periphery of the first spacer element P1 abuts against the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter-retarder plate QWP are located on the display side of the first spacer element P1. The second spacer element P2 is located between the second lens E2 and the third lens E3. A second spacer auxiliary element is also provided on the display side of the second spacer element P2. The surface of the second spacer element P2 near the human eye is at least partially in contact with the surface of the second lens E2 near the display. The surface of the second spacer element P2 near the display is at least partially in contact with the surface of the second spacer auxiliary element near the human eye. The surface of the second spacer auxiliary element near the display is at least partially in contact with the surface of the third lens E3 near the human eye. The outer periphery of both the second spacer element P2 and the second spacer auxiliary element is in contact with the inner wall surface of the lens barrel P0.

[0070] like Figure 3As shown, in the second state of the optical system, the first spacer element P1 is located between the first lens E1 and the second lens E2. The surface of the first spacer element P1 near the human eye simultaneously and at least partially abuts against the inner wall surface of the lens barrel P0 and the surface of the first lens E1 near the display. The surface of the first spacer element P1 near the display also at least partially abuts against the surface of the second lens E2 near the human eye. The outer periphery of the first spacer element P1 abuts against the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter-retarder plate QWP are located on the display side of the first spacer element P1. The second spacer element P2 is located between the second lens E2 and the third lens E3. A second spacer auxiliary element is also provided on the display side of the second spacer element P2. The surface of the second spacer element P2 near the human eye is at least partially in contact with the surface of the second lens E2 near the display. The surface of the second spacer element P2 near the display is at least partially in contact with the surface of the second spacer auxiliary element near the human eye. The surface of the second spacer auxiliary element near the display is at least partially in contact with the surface of the third lens E3 near the human eye. The outer periphery of both the second spacer element P2 and the second spacer auxiliary element is in contact with the inner wall surface of the lens barrel P0.

[0071] like Figure 4 As shown, in the third state of the optical system, the first spacer element P1 is located between the first lens E1 and the second lens E2. The eye-side surface of the first spacer element P1 is at least partially in contact with both the inner wall surface of the lens barrel P0 and the display-side surface of the first lens E1. The display-side surface of the first spacer element P1 is at least partially in contact with the eye-side surface of the second lens E2. The outer periphery of the first spacer element P1 is in contact with the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter-retarder plate QWP are located on the display-side of the first spacer element P1. The second spacer element P2 is located between the second lens E2 and the third lens E3. The eye-side surface of the second spacer element P2 is at least partially in contact with the display-side surface of the second lens E2. The display-side surface of the second spacer element P2 is at least partially in contact with the eye-side surface of the third lens E3. The outer periphery of the second spacer element P2 is in contact with the inner wall surface of the lens barrel P0.

[0072] In summary, the parameters of the optical system in Example 1 under the first state 1-1, the second state 1-2, and the third state 1-3 are shown in Table 1. (Unit: mm)

[0073]

[0074] Table 1

[0075] In the first example, the surface of the first lens close to the human eye is concave, and the surface of the first lens close to the display is convex. The surface of the second lens close to the human eye is planar, and the surface of the second lens close to the display is concave. The power of the third lens can be positive or negative, the surface of the third lens close to the human eye is convex, and the surface of the third lens close to the display is convex.

[0076] In the first example, the total effective focal length f of the optical system is 31.83 mm, the effective focal length FG1 of the first element group is 76.81 mm, the effective focal length FG2 of the second element group is -255.78 mm, the effective focal length FG3 of the third element group is 146.75 mm, the central thickness CT1 of the first lens on the optical axis is 8.96 mm, the distance T12 between the surface of the first lens close to the display and the surface of the second lens close to the human eye on the optical axis is 0.5 mm, the central thickness CT2 of the second lens on the optical axis is 3.78 mm, the distance T23 between the surface of the second lens close to the display and the surface of the third lens close to the human eye on the optical axis is 1.87 mm, and the central thickness CT3 of the third lens on the optical axis is 12.28 mm.

[0077] Table 2 shows the basic structure parameter table of the optical system of the first example, wherein the units of the curvature radius, thickness / distance are all millimeters (mm). The order of the following table is opposite to the light transmission direction, and the light emitted by the image plane IMG is imaged on the human eye side STO. The reflecting surface 2 in the following table is the surface where the first reflection occurs, that is, the interface between the reflective polarizing element RP and the quarter retardation plate QWP, and the reflecting surface 1 is the surface where the second reflection occurs, that is, the surface of the third lens close to the display, and the two surfaces realize two reflections.

[0078]

[0079] Table 2

[0080] In the first example, the surface of the first lens close to the human eye is concave, and the surface of the first lens close to the display is convex. The surface of the second lens close to the human eye is planar, and the surface of the second lens close to the display is concave. The power of the third lens can be positive or negative, the surface of the third lens close to the human eye is convex, and the surface of the third lens close to the display is convex.

[0081] Formula (1).

[0082] Wherein, x is the distance from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis direction, and the height is the distance from the vertex of the aspheric surface; c is the paraxial curvature of the aspheric surface, c = 1 / R, that is, the paraxial curvature c is the reciprocal of the curvature radius R in Table 1. Table 3 below gives the 4th order Qcon coefficient, 6th order Qcon coefficient, 8th order Qcon coefficient and 10th order Qcon coefficient of the aspheric surface which can be used in the first example.

[0083]

[0084] Table 3

[0085] Figure 5 An on-axis chromatic aberration curve of the optical system of Example One is shown, which represents the convergence point deviation of light rays of different wavelengths after passing through the optical system. Figure 6 An astigmatism curve of the optical system of Example One is shown, which represents the meridional image curvature and sagittal image curvature. Figure 7 A distortion curve of the optical system of Example One is shown, which represents the distortion size values corresponding to different field angles.

[0086] According to Figures 5 to 7 It can be known that the optical system given by Example One can achieve good imaging quality.

[0087] Example Two

[0088] As Figures 8 to 13 shown, the optical system of Example Two is described. Figure 8 An structural schematic diagram of the optical system of Example Two in a first state is shown, Figure 9 An structural schematic diagram of the optical system of Example Two in a second state is shown, Figure 10 An structural schematic diagram of the optical system of Example Two in a third state is shown.

[0089] As Figures 8 to 10 shown, the optical system includes a lens barrel P0, and a first element group, a second element group, and a third element group arranged in the lens barrel P0 in sequence from an eye side to a display side along an optical axis of the lens barrel P0, the first element group including a first lens E1, the second element group including a second lens E2, and the third element group including a third lens E3. The optical system further includes a reflective polarizing element RP and a quarter retardation plate QWP, and the reflective polarizing element RP and the quarter retardation plate QWP are combined on a surface of the second lens close to the eye side.

[0090] In Example Two, the optical system further includes a first spacer element P1 and a second spacer element P2, the first spacer element P1 is arranged between the first lens E1 and the second lens E2, and the second spacer element P2 is arranged between the second lens E2 and the third lens E3.

[0091] As Figure 8As shown, in the first state of the optical system, the first spacer element P1 is located between the first lens E1 and the second lens E2. The eye-side surface of the first spacer element P1 is at least partially in contact with both the inner wall surface of the lens barrel P0 and the display-side surface of the first lens E1. The display-side surface of the first spacer element P1 is at least partially in contact with the eye-side surface of the second lens E2. The outer periphery of the first spacer element P1 is in contact with the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter-retarder plate QWP are located on the display-side of the first spacer element P1. The second spacer element P2 is located between the second lens E2 and the third lens E3. The eye-side surface of the second spacer element P2 is at least partially in contact with the display-side surface of the second lens E2. The display-side surface of the second spacer element P2 is at least partially in contact with the eye-side surface of the third lens E3. The outer periphery of the second spacer element P2 is in contact with the inner wall surface of the lens barrel P0.

[0092] like Figure 9 As shown, in the second state of the optical system, the first spacer element P1 is located between the first lens E1 and the second lens E2. A first auxiliary spacer element is also provided on the eye-side of the first spacer element P1. The two side surfaces of the first auxiliary spacer element are at least partially in contact with the display-side surface of the first lens E1 and the eye-side surface of the first spacer element P1. The display-side surface of the first spacer element P1 is at least partially in contact with the eye-side surface of the second lens E2. The outer periphery of the first spacer element P1 is in contact with the inner wall surface of the lens barrel P0. A reflective polarizing element RP and a quarter-retarder plate QWP are located on the display-side of the first spacer element P1. The second spacer element P2 is located between the second lens E2 and the third lens E3. The eye-side surface of the second spacer element P2 is at least partially in contact with the display-side surface of the second lens E2 and the eye-side surface of the third lens E3. The outer periphery of the second spacer element P2 is in contact with the inner wall surface of the lens barrel P0.

[0093] like Figure 10As shown, in the third state, the first spacer element P1 is located between the first lens E1 and the second lens E2, the person-eye-side surface of the first spacer element P1 at least partially abuts against the inner wall surface of the lens barrel P0 and the display-side surface of the first lens E1, the display-side surface of the first spacer element P1 at least partially abuts against the person-eye-side surface of the second lens E2, and the outer periphery of the first spacer element P1 abuts against the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter retardation plate QWP are located on the display-side of the first spacer element P1. The second spacer element P2 is located between the second lens E2 and the third lens E3, the person-eye-side surface of the second spacer element P2 at least partially abuts against the display-side surface of the second lens E2, the display-side surface of the second spacer element P2 at least partially abuts against the person-eye-side surface of the third lens E3, and the outer periphery of the second spacer element P2 abuts against the inner wall surface of the lens barrel P0.

[0094] In summary, the parameters of the optical system of Example Two in the first state 2-1, the second state 2-2, and the third state 2-3 are shown in Table 4. (Unit: mm)

[0095]

[0096] Table 4

[0097] In Example Two, the person-eye-side surface of the first lens is concave, and the display-side surface of the first lens is convex. The person-eye-side surface of the second lens is planar, and the display-side surface of the second lens is convex. The optical power of the third lens can be positive or negative, the person-eye-side surface of the third lens is concave, and the display-side surface of the third lens is convex.

[0098] In Example Two, the total effective focal length f of the optical system is 31.65 mm, the effective focal length FG1 of the first element group is 76.19 mm, the effective focal length FG2 of the second element group is 12306 mm, the effective focal length FG3 of the third element group is 313 mm, the center thickness CT1 of the first lens on the optical axis is 9.05 mm, the distance T12 between the display-side surface of the first lens and the person-eye-side surface of the second lens on the optical axis is 0.5 mm, the center thickness CT2 of the second lens on the optical axis is 5.05 mm, the distance T23 between the display-side surface of the second lens and the person-eye-side surface of the third lens on the optical axis is 1.24 mm, and the center thickness CT3 of the third lens on the optical axis is 11.55 mm.

[0099] Table 5 shows the basic structural parameter table of the optical system of Example Two, in which the units of the curvature radius and the thickness / distance are millimeters (mm). In this example and the following examples, some similar descriptions as in Example One will be omitted for brevity.

[0100]

[0101] Table 5

[0102] Table 6 shows the high order term coefficients of each aspherical surface in Example Two, wherein each aspherical surface can be defined by the formula (1) given in Example One.

[0103]

[0104] Table 6

[0105] Figure 11 The on-axis chromatic aberration curve of the optical system in Example Two is shown, which represents the convergence point deviation of light rays of different wavelengths after passing through the optical system. Figure 12 The astigmatism curve of the optical system in Example Two is shown, which represents the meridional image curvature and sagittal image curvature. Figure 13 The distortion curve of the optical system in Example Two is shown, which represents the distortion size values corresponding to different field angles.

[0106] According to Figures 11 to 13 It can be seen that the optical system given in Example Two can achieve good imaging quality.

[0107] Example Three

[0108] As Figures 14 to 19 shown, the optical system in Example Three is described. Figure 14 A structural schematic diagram of the optical system in Example Three in a first state is shown, Figure 15 A structural schematic diagram of the optical system in Example Three in a second state is shown, Figure 16 A structural schematic diagram of the optical system in Example Three in a third state is shown.

[0109] As Figures 14 to 16 shown, the optical system includes a lens barrel P0, and a first element group, a second element group, and a third element group arranged in the lens barrel P0 in sequence from an eye side to a display side along an optical axis of the lens barrel P0, the first element group including a first lens E1, the second element group including a second lens E2, and the third element group including a third lens E3. The optical system further includes a reflective polarizing element RP and a quarter retardation plate QWP, and the reflective polarizing element RP and the quarter retardation plate QWP are combined on a surface of the second lens close to the eye side.

[0110] In Example Three, the optical system further includes a first spacing element P1 and a second spacing element P2, the first spacing element P1 is arranged between the first lens E1 and the second lens E2, and the second spacing element P2 is arranged between the second lens E2 and the third lens E3.

[0111] AsFigure 14 As shown, in the first state of the optical system, the first spacer element P1 is located between the first lens E1 and the second lens E2. The eye-side surface of the first spacer element P1 is at least partially in contact with both the inner wall surface of the lens barrel P0 and the display-side surface of the first lens E1. The display-side surface of the first spacer element P1 is at least partially in contact with the eye-side surface of the second lens E2. The outer periphery of the first spacer element P1 is in contact with the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter-retarder plate QWP are located on the display-side of the first spacer element P1. The second spacer element P2 is located between the second lens E2 and the third lens E3. The eye-side surface of the second spacer element P2 is at least partially in contact with the display-side surface of the second lens E2. The display-side surface of the second spacer element P2 is at least partially in contact with the eye-side surface of the third lens E3. The outer periphery of the second spacer element P2 is in contact with the inner wall surface of the lens barrel P0.

[0112] like Figure 15 As shown, in the second state of the optical system, the first spacer element P1 is located between the first lens E1 and the second lens E2. The eye-side surface of the first spacer element P1 is at least partially in contact with both the inner wall surface of the lens barrel P0 and the display-side surface of the first lens E1. The display-side surface of the first spacer element P1 is at least partially in contact with the eye-side surface of the second lens E2. The outer periphery of the first spacer element P1 is in contact with the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter-retarder plate QWP are located on the display-side of the first spacer element P1. The second spacer element P2 is located between the second lens E2 and the third lens E3. The eye-side surface of the second spacer element P2 is at least partially in contact with the display-side surface of the second lens E2. The display-side surface of the second spacer element P2 is at least partially in contact with the eye-side surface of the third lens E3. The outer periphery of the second spacer element P2 is in contact with the inner wall surface of the lens barrel P0.

[0113] like Figure 16As shown, in the third state, the first spacer element P1 is located between the first lens E1 and the second lens E2, the person-eye-side surface of the first spacer element P1 at least partially abuts against the inner wall surface of the lens barrel P0 and the display-side surface of the first lens E1, the display-side surface of the first spacer element P1 at least partially abuts against the person-eye-side surface of the second lens E2, and the outer periphery of the first spacer element P1 abuts against the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter retardation plate QWP are located on the display-side of the first spacer element P1. The second spacer element P2 is located between the second lens E2 and the third lens E3, the person-eye-side surface of the second spacer element P2 at least partially abuts against the display-side surface of the second lens E2, the display-side surface of the second spacer element P2 at least partially abuts against the person-eye-side surface of the third lens E3, and the outer periphery of the second spacer element P2 abuts against the inner wall surface of the lens barrel P0.

[0114] In summary, the parameters of the optical system of Example Three in the first state 3-1, the second state 3-2, and the third state 3-3 are shown in Table 7. (Unit: mm)

[0115]

[0116] Table 7

[0117] In Example Three, the person-eye-side surface of the first lens is concave, and the display-side surface of the first lens is convex. The person-eye-side surface of the second lens is planar, and the display-side surface of the second lens is convex. The optical power of the third lens can be positive or negative, the person-eye-side surface of the third lens is concave, and the display-side surface of the third lens is convex.

[0118] In Example Three, the total effective focal length f of the optical system is 31.22 mm, the effective focal length FG1 of the first element group is 109.11 mm, the effective focal length FG2 of the second element group is 125.06 mm, the effective focal length FG3 of the third element group is -310.88 mm, the center thickness CT1 of the first lens on the optical axis is 6.77 mm, the distance T12 between the display-side surface of the first lens and the person-eye-side surface of the second lens on the optical axis is 0.5 mm, the center thickness CT2 of the second lens on the optical axis is 12.01 mm, the distance T23 between the display-side surface of the second lens and the person-eye-side surface of the third lens on the optical axis is 0.94 mm, and the center thickness CT3 of the third lens on the optical axis is 5.23 mm.

[0119] Table 8 shows the basic structural parameter table of the optical system of Example Three, wherein the units of the curvature radius and the thickness / distance are millimeters (mm).

[0120]

[0121] Table 8

[0122] Table 9 shows the high order term coefficients of each aspherical surface used in Example 3, wherein each aspherical surface can be defined by the formula (1) given in Example 1 above.

[0123]

[0124] Table 9

[0125] Figure 17 The on-axis chromatic aberration curve of the optical system of Example 3 is shown, which represents the deviation of the converging focal points of light rays of different wavelengths after passing through the optical system. Figure 18 The astigmatism curve of the optical system of Example 3 is shown, which represents the meridional image curvature and sagittal image curvature. Figure 19 The distortion curve of the optical system of Example 3 is shown, which represents the distortion size values corresponding to different field angles.

[0126] According to Figures 17 to 19 It can be seen that the optical system given in Example 3 can achieve good imaging quality.

[0127] In summary, Examples 1 to 3 respectively satisfy the relationships shown in Table 10.

[0128]

[0129] Table 10

[0130] It should be noted that 1-1 in Table 10 represents the optical system in Example 1 in the first state, 1-2 represents the optical system in Example 1 in the second state, 1-3 represents the optical system in Example 1 in the third state, 2-1 represents the optical system in Example 2 in the first state, 2-2 represents the optical system in Example 2 in the second state, 2-3 represents the optical system in Example 2 in the third state, 3-1 represents the optical system in Example 3 in the first state, 3-2 represents the optical system in Example 3 in the second state, and 3-3 represents the optical system in Example 3 in the third state.

[0131] The present application also provides an imaging device, the electronic photosensitive element of which can be a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The imaging device can be a stand-alone imaging apparatus such as a digital camera, or an imaging module integrated on a mobile electronic device such as a mobile phone. The imaging device is equipped with the optical system described above.

[0132] Obviously, the above-described embodiments are only some, but not all of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall within the protection scope of the present application.

[0133] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments consistent with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, devices, components and / or combinations thereof.

[0134] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments consistent with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, devices, components and / or combinations thereof.

[0135] The preferred embodiments of the present application have been described above with the aid of drawing figures, and are not limited to those embodiments; instead, they will include, in addition to the above-described embodiments, all embodiments that are equivalent in whole or in part to the embodiments described above, and fall within the scope of the present application.

Claims

1. An optical system characterized by comprising: An optical system includes a lens barrel and a first element group, a second element group, and a third element group disposed in the lens barrel in order from a human eye side to a display side, the total number of lenses of the optical system being three, The first element group includes at least a first lens having a positive refractive power, a surface of the first lens on the human eye side being concave, and a surface of the first lens on the display side being convex. The second element group includes at least a second lens, a surface of the second lens on the human eye side being flat. The third element group includes at least a third lens, a surface of the third lens on the display side being convex. The optical system further includes a plurality of spacer elements including at least a first spacer element and a second spacer element, the first spacer element being located between the first element group and the second element group and at least partially abutting the first element group, and the second spacer element being located between the second element group and the third element group and at least partially abutting the second element group. The optical system further includes a reflective polarizing element and a quarter retardation plate, the reflective polarizing element and the quarter retardation plate being combined on a surface of the second lens on the human eye side. An effective focal length FG1 of the first element group, a maximum thickness CP1 of the first spacer element, and a distance EP12 along an optical axis of a surface of the first spacer element on the display side and a surface of the second spacer element on the human eye side satisfy 5.86 ≤ FG1 / (CP1+EP12) < 10.

8. A central thickness CT1 of the first lens on the optical axis, a central thickness CT2 of the second lens on the optical axis, and the distance EP12 along the optical axis of the surface of the first spacer element on the display side and the surface of the second spacer element on the human eye side satisfy 1.1 < (CT1+CT2) / EP12 ≤ 4.

72.

2. The optical system of claim 1, wherein The central thickness CT1 of the first lens on the optical axis, a distance T12 on the optical axis of the surface of the first lens on the display side and the surface of the second lens on the human eye side, the distance EP12 along the optical axis of the surface of the first spacer element on the display side and the surface of the second spacer element on the human eye side, and a central thickness CP2 of the second lens on the optical axis satisfy 0.4 < (CT1×T12) / (EP12×CP2) < 9.

9.

3. The optical system of claim 1, wherein An outer diameter D1s of the surface of the first spacer element on the human eye side, an inner diameter d1s of the surface of the first spacer element on the human eye side, and the central thickness CT2 of the second lens on the optical axis satisfy 1.48 ≤ (D1s-d1s) / CT2 < 4.

9. A curvature radius R1 of the surface of the first lens on the human eye side, an outer diameter D1m of the surface of the first spacer element on the display side, and an inner diameter d1m of the surface of the first spacer element on the display side satisfy 36.6 < |R1| / (D1m-d1m) ≤ 381.

75.

4. The optical system of claim 1, wherein An inner diameter d2s of the second spacer element on a human eye side surface, an outer diameter D2s of the second spacer element on the human eye side surface, and a curvature radius R2 of the first lens on a display side surface satisfy: 2.79 ≤ (d2s + D2s) / |R2| ≤ 3.

44.

5. The optical system of claim 1, wherein A distance T12 on an optical axis of the display side surface of the first lens and the human eye side surface of the second lens, a distance T23 on the optical axis of the display side surface of the second lens and the human eye side surface of the third lens, and a maximum thickness CP2 of the second spacer element satisfy: 1.1 < (T12 + T23) / CP2 ≤ 23.

70.

6. The optical system of claim 1, wherein A curvature radius R4 of the display side surface of the second lens, a curvature radius R5 of the human eye side surface of the third lens, an outer diameter D2s of the human eye side surface of the second spacer element, and an outer diameter D2m of the display side surface of the second spacer element satisfy: 1.00 ≤ |R4 + R5| / (D2s + D2m) ≤ 49.

80.

7. The optical system of claim 1, wherein A curvature radius R5 of the human eye side surface of the third lens, a curvature radius R6 of the display side surface of the third lens, an inner diameter d2m of the display side surface of the second spacer element, and an inner diameter d2s of the human eye side surface of the second spacer element satisfy: 1.6 < (|R5| + |R6|) / (d2m + d2s) < 5.

9.

8. The optical system of claim 1, wherein, A combined focal length FG2 of the second element group, an inner diameter d2s of the human eye side surface of the second spacer element, and an inner diameter d2m of the display side surface of the second spacer element satisfy: 0.97 ≤ FG2 / (d2s + d2m) < 97.

2.

9. The optical system according to any one of claims 1 to 8, characterized in that, The material of the first lens is the same as the material of the third lens.

Images