Optical system

Abstract

The invention provides an optical system. The optical system comprises a lens barrel, and a first element group, a second element group and a third element group which are sequentially arranged in the lens barrel from the human eye side to the display side, and the first element group at least comprises a first lens; the second element group at least comprises a second lens; the third element group at least comprises a third lens; the plurality of spacing elements at least comprise a first spacing element and a second spacing element, the first spacing element is located between the first element group and the second element group and at least partially abuts against the first element group, and the second spacing element is located between the second element group and the third element group and at least partially abuts against the second element group; the effective focal length FG1 of the first element group, the maximum thickness CP1 of the first spacing element and the spacing EP12 between the side surface, close to the display, of the first spacing element and the side surface, close to the human eye, of the second spacing element along the optical axis meet the following conditions: 5.8 lt; fG1 / (CP1 + EP12) lt; and 10.8. According to the invention, the problem that the overall length of a learning system in the prior art is relatively long is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical imaging equipment, and in particular to an optical system. Background Art

[0002] With the continuous development of optical imaging, various optical display devices have entered people's lives. At the same time, with the continuous increase in 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 the entrance to human-computer interaction, VR optical systems play an important role. On the one hand, the imaging quality of VR optical systems needs to meet the resolution requirements of the human eye; on the other hand, early aspherical or Fresnel lenses have more structures and longer bodies, which makes the center of gravity forward when users wear them on their heads, resulting in a poor experience.

[0004] That is to say, the optical system in the prior art has the problem of being relatively long in overall length. Summary of the invention

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

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

[0007] Furthermore, the optical system also includes a reflective polarizing element and a quarter retardation plate, which are combined on the surface of the first lens side close to the display or on the surface of the second lens side close to the human eye.

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

[0009] Further, the curvature radius R1 of the first lens surface close to the human eye, the outer diameter D1m of the first spacing element surface close to the display side and the inner diameter d1m of the first spacing element surface close to the display side satisfy: 36.6<|R1| / (D1m-d1m)<381.8.

[0010] Further, the center thickness CT1 of the first lens on the optical axis, the distance T12 between the side surface of the first lens close to the display and the side surface of the second lens close to the human eye on the optical axis, the interval EP12 along the optical axis between the side surface of the first spacing element close to the display and the side surface of the second spacing element close to the human eye, and the center thickness CP2 of the second lens on the optical axis satisfy: 0.4<(CT1*T12) / (EP12*CP2)<9.9.

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

[0012] Further, the center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, and the interval EP12 along the optical axis between the side surface of the first spacing element close to the display and the side surface of the second spacing element close to the human eye satisfy: 1.1<(CT1+CT2) / EP12<4.8.

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

[0014] Further, the curvature radius R4 of the second lens close to the display surface, the curvature radius R5 of the third lens close to the side surface of the human eye, the outer diameter D2s of the second spacing element close to the side surface of the human eye and the outer diameter D2m of the second spacing element close to the side surface of the display satisfy: 0.9<|R4+R5| / (D2s+D2m)<50.0.

[0015] Further, the curvature radius R5 of the third lens's side surface close to the human eye, the curvature radius R6 of the third lens's side surface close to the display, the inner diameter d2m of the second spacing element's side surface close to the display, and the inner diameter d2s of the second spacing element's side surface close to the human eye satisfy: 1.6<(|R5|+|R6|) / (d2m+d2s)<5.9.

[0016] Furthermore, the combined focal length FG2 of the second element group, the inner diameter d2s of the second spacing element near the side surface of the human eye and the inner diameter d2m of the second spacing element near the side surface of the display satisfy: 0.9 <FG2 / (d2s+d2m)<97.2。

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

[0018] According to the technical solution of the present invention, the optical system includes a lens barrel and a first element group, a second element group and a third element group which are arranged in sequence from the human eye side to the display side in the lens barrel, wherein the first element group includes at least a first lens; the second element group includes at least a second lens; and the third element group includes at least a third lens; the optical system also includes a plurality of spacing elements, wherein the plurality of spacing elements include at least a first spacing element and a second spacing element, wherein the first spacing element is located between the first element group and the second element group and at least partially abuts against the first element group, and the second spacing element is located between the second element group and the third element group and at least partially abuts against 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 spacing EP12 along the optical axis between the surface of the first spacing element close to the display side and the surface of the second spacing element close to the human eye side satisfy the following conditions: 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, so that the overall length of the optical system is greatly compressed, thereby avoiding the situation where the center of gravity of the user is forward when wearing the device on the head, and improving the user experience. By providing a first spacing element and a second spacing element between adjacent element groups, and at the same time reasonably constraining the effective focal length of the first element group, the maximum thickness of the first spacing element, and the spacing between the first spacing element and the second spacing element, the shape of the first lens can be effectively controlled, and the molding difficulty of the first lens can be reduced. At the same time, the spacing elements are all supported by the inner wall surface of the lens barrel, and the straight position size is reasonably controlled, and the requirements for the linear contour line of the matching part of the lens barrel and the spacing element are reduced, thereby reducing the difficulty of the assembly process of the optical system and improving the yield of the assembly process of the optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 A dimensioned diagram showing an optical system of an alternative embodiment of the present invention;

[0022] Figure 2 A schematic diagram showing the structure of an optical system in Example 1 of the present invention in a first state;

[0023] Figure 3 A schematic diagram showing the structure of the optical system of Example 1 of the present invention in a second state;

[0024] Figure 4 A schematic diagram showing the structure of the optical system of Example 1 of the present invention in a third state;

[0025] Figures 5 to 7 The axial chromatic aberration curve, the astigmatism curve and the distortion curve of Example 1 of the present invention are respectively shown;

[0026] Figure 8 A schematic diagram showing the structure of an optical system in a first state according to Example 2 of the present invention is shown;

[0027] Fig. 9 A schematic diagram showing the structure of the optical system of Example 2 of the present invention in the second state;

[0028] Fig.10 A schematic diagram showing the structure of the optical system of Example 2 of the present invention in a third state;

[0029] Figures 11 to 13 The axial chromatic aberration curve, astigmatism curve and distortion curve of Example 2 of the present invention are respectively shown;

[0030] Fig.14 A schematic diagram showing the structure of an optical system in a first state according to Example 3 of the present invention is shown;

[0031] Fig.15 A schematic diagram showing the structure of the optical system of Example 3 of the present invention in the second state;

[0032] Fig.16 A schematic diagram showing the structure of the optical system of Example 3 of the present invention in a third state;

[0033] Figures 17 to 19 The axial chromatic aberration curve, astigmatism curve and distortion curve of Example 3 of the present invention are respectively shown.

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

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

[0036] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

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

[0038] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity directions; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above-mentioned directional words are not used to limit the present invention.

[0039] It should be noted that in this 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, without departing from the teaching of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

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

[0041] In this article, the paraxial area refers to the area near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial area; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial area. The judgment of the surface shape in the paraxial area can be based on the judgment method of ordinary knowledgeable people in this field, and the positive and negative R value (R refers to the radius of curvature of the paraxial area, usually refers to the R value on the lens database (lens data) in the optical software) is used to judge the convexity and concavity. For the light incident side, when the R value is positive, it is judged as a convex surface, and when the R value is negative, it is judged as a concave surface; for the light exiting side, when the R value is positive, it is judged as a concave surface, and when the R value is negative, it is judged as a convex surface.

[0042] In order to solve the problem of the optical system in the prior art having a relatively long overall length, the present invention provides an optical system.

[0043] like Figures 1 to 19 As shown, the optical system includes a lens barrel and a first element group, a second element group and a third element group arranged in sequence from the human eye side to the display side in the lens barrel, the first element group includes at least a first lens; the second element group includes at least a second lens; the third element group includes at least a third lens; the optical system also includes a plurality of spacing elements, the plurality of spacing elements include at least a first spacing element and a second spacing element, the first spacing element is located between the first element group and the second element group and at least partially abuts against the first element group, the second spacing element is located between the second element group and the third element group and at least partially abuts against the second element group; the effective focal length FG1 of the first element group, the maximum thickness CP1 of the first spacing element and the spacing EP12 along the optical axis between the surface of the first spacing element close to the display side and the surface of the second spacing element close to the human eye side meet the following conditions: 5.8 <FG1 / (CP1+EP12)<10.8。

[0044] 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, so that the overall length of the optical system is greatly compressed, thereby avoiding the situation where the center of gravity of the user is forward when wearing the device on the head, and improving the user experience. By providing a first spacing element and a second spacing element between adjacent element groups, and at the same time reasonably constraining the effective focal length of the first element group, the maximum thickness of the first spacing element, and the spacing between the first spacing element and the second spacing element, the shape of the first lens can be effectively controlled, and the molding difficulty of the first lens can be reduced. At the same time, the spacing elements are all supported by the inner wall surface of the lens barrel, and the straight position size is reasonably controlled, and the requirements for the linear contour line of the matching part of the lens barrel and the spacing element are reduced, thereby reducing the difficulty of the assembly process of the optical system and improving the yield of the assembly process of the optical system.

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

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

[0047] In this embodiment, the outer diameter D1s of the first spacer element close to the side surface of the human eye, the inner diameter d1s of the first spacer element close to the side surface of the human eye, and the center thickness CT2 of the second lens on the optical axis satisfy: 1.4<(D1s-d1s) / CT2<4.9. This conditional expression is satisfied, and the processability of the second lens is improved while ensuring the assembly of the system; at the same time, by controlling the inner diameter and outer diameter of the first spacer element close to the side surface of the human eye, the support of the structure to the lens is satisfied while ensuring the processability of the second spacer element. Preferably, 1.48≤(D1s-d1s) / CT2≤4.53.

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

[0049] In this embodiment, the center thickness CT1 of the first lens on the optical axis, the distance T12 between the side surface of the first lens close to the display and the side surface of the second lens close to the human eye on the optical axis, the interval EP12 along the optical axis between the side surface of the first spacing element close to the display and the side surface of the second spacing element close to the human eye, and the center thickness CP2 of the second lens on the optical axis satisfy: 0.4<(CT1*T12) / (EP12*CP2)<9.9. By controlling this conditional expression, the main purpose is to improve stray light. Since the light rays of the first lens and the second lens are steeper and the thickness of the first spacing element in the middle is larger, more stray light will be generated. Therefore, controlling the center thickness of the second lens on the optical axis and EP12 within a certain range is conducive to reducing the reflection of excess light and improving imaging quality. Preferably, 0.42≤(CT1*T12) / (EP12*CP2)≤9.88.

[0050] In this embodiment, the inner diameter d2s of the second spacer element near the side surface of the human eye, the outer diameter D2s of the second spacer element near the side surface of the human eye, and the curvature radius R2 of the first lens near the display side surface satisfy: 2.7<(d2s+D2s) / |R2|<3.5. By controlling this condition, the maximum shape of the lens barrel can be limited, which is conducive to achieving the compactness of the optical system. At the same time, controlling the curvature radius of the first lens near the display side surface 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 this embodiment, the center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, and the interval EP12 along the optical axis between the side surface of the first spacing element close to the display and the side surface of the second spacing element close to the human eye satisfy: 1.1<(CT1+CT2) / EP12<4.8. By controlling the center thickness of the first lens, the second lens, and EP12, the thickness ratio of the second lens can be guaranteed, which is beneficial to the molding of the first lens and the second lens. Preferably, 1.13≤(CT1+CT2) / EP12≤4.72.

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

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

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

[0055] In this embodiment, the combined 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 this condition control, the light trend can be effectively controlled to avoid the problem of too high sensitivity of the lens caused by too steep light. 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 is blocked, which helps to improve the overall stray light of the optical system. Preferably, 0.97 ≤ FG2 / (d2s + d2m) ≤ 97.16.

[0056] In this embodiment, the materials of the first lens and the third lens are the same. By controlling the materials of the first lens and the third lens to be the same, it is beneficial to ensure that the refractive indices of the first lens and the third lens are consistent, which is beneficial to restricting the material selection of the second lens and reducing the stress of the lens material, thereby improving the polarization efficiency of the optical system.

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

[0058] The optical system in this application can use multiple lenses, such as the three lenses described above. In this application, at least one of the lens surfaces of each lens is an aspherical surface. The characteristics of an aspherical lens are that the curvature changes continuously from the center of the lens to the periphery of the lens. Different from a spherical lens with a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has better curvature radius characteristics and has the advantages of improving distortion aberration and astigmatism aberration. After using an aspherical lens, the aberration that appears during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0059] However, those skilled in the art should understand that without departing from the technical solution required to be protected in this application, the number of lenses constituting the optical system can be changed to obtain the various results and advantages described in this specification. For example, although the three-lens example is described in the embodiment, the optical system is not limited to including three lenses. If necessary, the optical system may further include other numbers of lenses.

[0060] Figure 1 The structural schematic diagram of an optical system of this application is shown, where Figure 1Parameters such as D2s, D1s, d2s, d1s, d2m, d1m, D1m, D2m, CT1, T12, CT2, T13, CT3, CP1, CP2, and EP12 are marked in the figure to clearly and intuitively understand the meaning of the parameters. In order to facilitate the optical system and specific surface types, these parameters will no longer be reflected in the drawings when describing specific examples later.

[0061] like Figures 1 to 19 As shown, the optical system includes a lens barrel and a first element group, a second element group and a third element group arranged in sequence in the lens barrel from the human 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 also includes a reflective polarizing element and a quarter retardation plate. The reflective polarizing element and the quarter retardation plate are combined on the surface of the second lens close to the human eye side, that is, the reflective polarizing element, the quarter retardation plate and the surface of the second lens close to the human eye side are equivalent to a whole. As shown Figure 1 As shown, the black arrow is the direction of light transmission, the left side is the human eye side, and the right side is the display side, that is, STO is the human eye side, and IMG is the display side and also the image plane; the light on the display side passes through the third lens and the second lens in sequence and is incident on the interface between 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 in sequence, the quarter retardation plate, the reflective polarizing element and the first lens to form an image on the human eye side.

[0062] The following further describes examples of specific surface shapes and parameters of the optical system applicable to the above-mentioned embodiments with reference to the accompanying drawings.

[0063] It should be noted that in the following examples, there are the first state, the second state and the third state, and in the same example, the parameters such as the curvature radius, the center thickness of the first lens to the third lens of the optical system in the first state, the second state and the third state, as well as the spacing distance and the coefficient of the higher order terms are the same, but the parameters such as the thickness, the inner diameter and the outer diameter of the lens barrel, the first spacing element and the second spacing element, and the shapes of some lenses are different. In other words, the main structure for imaging is the same, but the auxiliary structure for imaging is different.

[0064] It should be noted that any one of the following examples 1 to 3 is applicable to all embodiments of the present application.

[0065] Example 1

[0066] like Figures 2 to 7 As shown, the optical system of Example 1 is described. Figure 2FIG. 4 shows a schematic diagram of the structure of the optical system of Example 1 in the first state. Figure 3 FIG. 4 shows a schematic diagram of the structure of the optical system of Example 1 in the second state. Figure 4 A schematic diagram of the structure of the optical system of 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 arranged in the lens barrel P0 in sequence 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 retardation plate QWP, and the reflective polarizing element RP and the quarter retardation plate QWP are combined on the surface of the second lens near the human eye side.

[0068] In Example 1, the optical system further includes a first spacing element P1 and a second spacing element P2, the first spacing element P1 is disposed between the first lens E1 and the second lens E2, and the second spacing 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 spacing element P1 is located between the first lens E1 and the second lens E2, the surface of the first spacing element P1 close to the human eye is at least partially in contact with the inner wall surface of the lens barrel P0 and the surface of the first lens E1 close to the display at the same time, the surface of the first spacing element P1 close to the display is at least partially in contact with the surface of the second lens E2 close to the human eye, and the outer periphery of the first spacing element P1 is in contact with the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter retardation plate QWP are located on the side of the first spacing element P1 close to the display. The second spacing element P2 is located between the second lens E2 and the third lens E3, and a second spacing auxiliary element is also provided on the side of the second spacing element P2 close to the display. The surface of the second spacing element P2 close to the human eye side at least partially abuts against the surface of the second lens E2 close to the display side, the surface of the second spacing element P2 close to the display side at least partially abuts against the surface of the second spacing auxiliary element close to the human eye side, the surface of the second spacing auxiliary element close to the display side at least partially abuts against the surface of the third lens E3 close to the human eye side, and the outer peripheral edges of the second spacing element P2 and the second spacing auxiliary element both abut against the inner wall surface of the lens barrel P0.

[0070] like Figure 3As shown, in the second state of the optical system, the first spacing element P1 is located between the first lens E1 and the second lens E2, the surface of the first spacing element P1 close to the human eye is at least partially in contact with the inner wall surface of the lens barrel P0 and the surface of the first lens E1 close to the display at the same time, the surface of the first spacing element P1 close to the display is at least partially in contact with the surface of the second lens E2 close to the human eye, and the outer periphery of the first spacing element P1 is in contact with the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter retardation plate QWP are located on the side of the first spacing element P1 close to the display. The second spacing element P2 is located between the second lens E2 and the third lens E3, and a second spacing auxiliary element is also provided on the side of the second spacing element P2 close to the display. The surface of the second spacing element P2 close to the human eye side at least partially abuts against the surface of the second lens E2 close to the display side, the surface of the second spacing element P2 close to the display side at least partially abuts against the surface of the second spacing auxiliary element close to the human eye side, the surface of the second spacing auxiliary element close to the display side at least partially abuts against the surface of the third lens E3 close to the human eye side, and the outer peripheral edges of the second spacing element P2 and the second spacing auxiliary element both abut against 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 spacing element P1 is located between the first lens E1 and the second lens E2, the surface of the first spacing element P1 close to the human eye is at least partially in contact with the inner wall surface of the lens barrel P0 and the surface of the first lens E1 close to the display at the same time, the surface of the first spacing element P1 close to the display is at least partially in contact with the surface of the second lens E2 close to the human eye, and the outer periphery of the first spacing element P1 is in contact with the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter retardation plate QWP are located on the side of the first spacing element P1 close to the display. The second spacing element P2 is located between the second lens E2 and the third lens E3, the surface of the second spacing element P2 close to the human eye is at least partially in contact with the surface of the second lens E2 close to the display, the surface of the second spacing element P2 close to the display is at least partially in contact with the surface of the third lens E3 close to the human eye, and the outer periphery of the second spacing element P2 is in contact with the inner wall surface of the lens barrel P0.

[0072] In summary, the parameters of the optical system of Example 1 in 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]

[0075] Table 1

[0076] In Example 1, the surface of the first lens near the human eye is concave, and the surface of the first lens near the display is convex. The surface of the second lens near the human eye is flat, and the surface of the second lens near the display is convex. The focal power of the third lens can be positive or negative, and the surface of the third lens near the human eye is concave, and the surface of the third lens near the display is convex.

[0077] In Example 1, 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 center thickness CT1 of the first lens on the optical axis is 8.96 mm, the distance T12 between the side surface of the first lens close to the display and the side surface of the second lens close to the human eye on the optical axis is 0.5 mm, the center thickness CT2 of the second lens on the optical axis is 3.78 mm, the distance T23 between the side surface of the second lens close to the display and the side surface of the third lens close to the human eye on the optical axis is 1.87 mm, and the center thickness CT3 of the third lens on the optical axis is 12.28 mm.

[0078] Table 2 shows the basic structural parameters of the optical system of Example 1, where the units of the radius of curvature and thickness / distance are all in millimeters (mm). The order of the following table is opposite to the direction of light transmission, and the light emitted by the image plane IMG is imaged on the human eye side STO. The reflection surface 2 in the following table is the surface where the first reflection occurs, that is, the interface between the reflective polarizer RP and the quarter retardation plate QWP, and the reflection surface 1 is the surface where the second reflection occurs, that is, the surface of the third lens close to the display side, and two reflections are achieved through these two surfaces.

[0079]

[0080]

[0081] Table 2

[0082] In Example 1, the surface shape of each aspheric lens can be defined by but not limited to the following aspheric formula:

[0083]

[0084] Wherein, x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis; 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 the above Table 1. The following Table 3 gives the 4th order Qcon coefficient, 6th order Qcon coefficient, 8th order Qcon coefficient and 10th order Qcon coefficient that can be used for each aspheric surface in Example 1.

[0085]

[0086] Table 3

[0087] Figure 5 The axial chromatic aberration curve of the optical system of Example 1 is shown, which indicates the deviation of the focusing point of light of different wavelengths after passing through the optical system. Figure 6 An astigmatism curve of the optical system of Example 1 is shown, which indicates meridional field curvature and sagittal field curvature. Figure 7 The distortion curve of the optical system of Example 1 is shown, which represents the distortion magnitude values ​​corresponding to different field angles.

[0088] according to Figures 5 to 7 It can be seen that the optical system given in Example 1 can achieve good imaging quality.

[0089] Example 2

[0090] like Figures 8 to 13 As shown, the optical system of Example 2 is described. Figure 8 FIG. 4 shows a schematic diagram of the structure of the optical system of Example 2 in the first state. Fig. 9 FIG. 4 shows a schematic diagram of the structure of the optical system of Example 2 in the second state. Fig.10 A schematic diagram of the structure of the optical system of Example 2 in the third state is shown.

[0091] like Figures 8 to 10 As 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 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 retardation plate QWP, and the reflective polarizing element RP and the quarter retardation plate QWP are combined on the surface of the second lens near the human eye side.

[0092] In Example 2, the optical system further includes a first spacing element P1 and a second spacing element P2, the first spacing element P1 is disposed between the first lens E1 and the second lens E2, and the second spacing element P2 is disposed between the second lens E2 and the third lens E3.

[0093] like Figure 8As shown, in the first state of the optical system, the first spacing element P1 is located between the first lens E1 and the second lens E2, the surface of the first spacing element P1 close to the human eye is at least partially in contact with the inner wall surface of the lens barrel P0 and the surface of the first lens E1 close to the display at the same time, the surface of the first spacing element P1 close to the display is at least partially in contact with the surface of the second lens E2 close to the human eye, and the outer periphery of the first spacing element P1 is in contact with the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter retardation plate QWP are located on the side of the first spacing element P1 close to the display. The second spacing element P2 is located between the second lens E2 and the third lens E3, the surface of the second spacing element P2 close to the human eye is at least partially in contact with the surface of the second lens E2 close to the display, the surface of the second spacing element P2 close to the display is at least partially in contact with the surface of the third lens E3 close to the human eye, and the outer periphery of the second spacing element P2 is in contact with the inner wall surface of the lens barrel P0.

[0094] like Fig. 9 As shown, in the second state of the optical system, the first spacing element P1 is located between the first lens E1 and the second lens E2, and a first auxiliary spacing element is further provided on the side of the first spacing element P1 close to the human eye. The two side surfaces of the first auxiliary spacing element are respectively in at least partial contact with the side surface of the first lens E1 close to the display, the side surface of the first spacing element P1 close to the human eye, the side surface of the first spacing element P1 close to the display and the side surface of the second lens E2 close to the human eye, and the outer periphery of the first spacing element P1 is in contact with the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter retardation plate QWP are located on the side of the first spacing element P1 close to the display. The second spacing element P2 is located between the second lens E2 and the third lens E3, the side surface of the second spacing element P2 close to the human eye is at least partially in contact with the side surface of the second lens E2 close to the display, the side surface of the second spacing element P2 close to the display and the side surface of the third lens E3 close to the human eye, and the outer periphery of the second spacing element P2 is in contact with the inner wall surface of the lens barrel P0.

[0095] like Fig.10As shown, in the third state of the optical system, the first spacing element P1 is located between the first lens E1 and the second lens E2, the surface of the first spacing element P1 close to the human eye is at least partially in contact with the inner wall surface of the lens barrel P0 and the surface of the first lens E1 close to the display at the same time, the surface of the first spacing element P1 close to the display is at least partially in contact with the surface of the second lens E2 close to the human eye, and the outer periphery of the first spacing element P1 is in contact with the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter retardation plate QWP are located on the side of the first spacing element P1 close to the display. The second spacing element P2 is located between the second lens E2 and the third lens E3, the surface of the second spacing element P2 close to the human eye is at least partially in contact with the surface of the second lens E2 close to the display, the surface of the second spacing element P2 close to the display is at least partially in contact with the surface of the third lens E3 close to the human eye, and the outer periphery of the second spacing element P2 is in contact with the inner wall surface of the lens barrel P0.

[0096] In summary, the parameters of the optical system of Example 2 in the first state 2-1, the second state 2-2, and the third state 2-3 are shown in Table 4. (Unit: mm)

[0097]

[0098]

[0099] Table 4

[0100] In Example 2, the surface of the first lens near the human eye is concave, and the surface of the first lens near the display is convex. The surface of the second lens near the human eye is flat, and the surface of the second lens near the display is convex. The focal power of the third lens can be positive or negative, and the surface of the third lens near the human eye is concave, and the surface of the third lens near the display is convex.

[0101] In Example 2, 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 side surface of the first lens close to the display and the side surface of the second lens close to the human eye 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 side surface of the second lens close to the display and the side surface of the third lens close to the human eye 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.

[0102] Table 5 shows the basic structural parameters of the optical system of Example 2, wherein the units of the radius of curvature and thickness / distance are all in millimeters. In this example and the following examples, for the sake of brevity, some descriptions similar to Example 1 will be omitted.

[0103]

[0104] Table 5

[0105] Table 6 shows the high-order coefficients that can be used for each aspheric surface in Example 2, wherein each aspheric surface shape can be defined by formula (1) given in Example 1 above.

[0106]

[0107] Table 6

[0108] Fig.11 The axial chromatic aberration curve of the optical system of Example 2 is shown, which indicates the deviation of the focal point of light of different wavelengths after passing through the optical system. Fig.12 An astigmatism curve of the optical system of Example 2 is shown, which indicates meridional field curvature and sagittal field curvature. Fig.13 The distortion curve of the optical system of Example 2 is shown, which represents the distortion magnitude values ​​corresponding to different field angles.

[0109] according to Figures 11 to 13 It can be seen that the optical system given in Example 2 can achieve good imaging quality.

[0110] Example 3

[0111] like Figures 14 to 19 As shown, the optical system of Example 3 is described. Fig.14 FIG. 4 shows a schematic diagram of the structure of the optical system of Example 3 in the first state. Fig.15 FIG. 4 shows a schematic diagram of the structure of the optical system of Example 3 in the second state. Fig.16 A schematic structural diagram of the optical system of Example 3 in the third state is shown.

[0112] like Figures 14 to 16 As 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 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 retardation plate QWP, and the reflective polarizing element RP and the quarter retardation plate QWP are combined on the surface of the second lens near the human eye side.

[0113] In Example 3, the optical system further includes a first spacing element P1 and a second spacing element P2, the first spacing element P1 is disposed between the first lens E1 and the second lens E2, and the second spacing element P2 is disposed between the second lens E2 and the third lens E3.

[0114] like Fig.14 As shown, in the first state of the optical system, the first spacing element P1 is located between the first lens E1 and the second lens E2, the surface of the first spacing element P1 close to the human eye is at least partially in contact with the inner wall surface of the lens barrel P0 and the surface of the first lens E1 close to the display at the same time, the surface of the first spacing element P1 close to the display is at least partially in contact with the surface of the second lens E2 close to the human eye, and the outer periphery of the first spacing element P1 is in contact with the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter retardation plate QWP are located on the side of the first spacing element P1 close to the display. The second spacing element P2 is located between the second lens E2 and the third lens E3, the surface of the second spacing element P2 close to the human eye is at least partially in contact with the surface of the second lens E2 close to the display, the surface of the second spacing element P2 close to the display is at least partially in contact with the surface of the third lens E3 close to the human eye, and the outer periphery of the second spacing element P2 is in contact with the inner wall surface of the lens barrel P0.

[0115] like Fig.15 As shown, in the second state of the optical system, the first spacing element P1 is located between the first lens E1 and the second lens E2, the surface of the first spacing element P1 close to the human eye side is at least partially in contact with the inner wall surface of the lens barrel P0 and the surface of the first lens E1 close to the display side, the surface of the first spacing element P1 close to the display side is at least partially in contact with the surface of the second lens E2 close to the human eye side, and the outer periphery of the first spacing element P1 is in contact with the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter retardation plate QWP are located on the side of the first spacing element P1 close to the display. The second spacing element P2 is located between the second lens E2 and the third lens E3, the surface of the second spacing element P2 close to the human eye side is at least partially in contact with the surface of the second lens E2 close to the display side, the surface of the second spacing element P2 close to the display side is at least partially in contact with the surface of the third lens E3 close to the human eye side, and the outer periphery of the second spacing element P2 is in contact with the inner wall surface of the lens barrel P0.

[0116] like Fig.16As shown, in the third state of the optical system, the first spacing element P1 is located between the first lens E1 and the second lens E2, the surface of the first spacing element P1 close to the human eye is at least partially in contact with the inner wall surface of the lens barrel P0 and the surface of the first lens E1 close to the display at the same time, the surface of the first spacing element P1 close to the display is at least partially in contact with the surface of the second lens E2 close to the human eye, and the outer periphery of the first spacing element P1 is in contact with the inner wall surface of the lens barrel P0. The reflective polarizing element RP and the quarter retardation plate QWP are located on the side of the first spacing element P1 close to the display. The second spacing element P2 is located between the second lens E2 and the third lens E3, the surface of the second spacing element P2 close to the human eye is at least partially in contact with the surface of the second lens E2 close to the display, the surface of the second spacing element P2 close to the display is at least partially in contact with the surface of the third lens E3 close to the human eye, and the outer periphery of the second spacing element P2 is in contact with the inner wall surface of the lens barrel P0.

[0117] In summary, the parameters of the optical system of Example 3 in the first state 3-1, the second state 3-2, and the third state 3-3 are shown in Table 7. (Unit: mm)

[0118] Parameters / Status 3-1 3-2 3-3 d1s 51.66 51.66 51.66 d1m 65.69 65.69 65.69 D1s 69.88 69.88 69.38 D1m 70.98 70.98 70.48 d2s 64.70 64.70 64.70 d2m 64.70 64.70 64.70 D2s 74.06 74.06 73.56 D2m 74.06 74.06 73.56 CP1 6.15 6.15 6.15 EP12 3.98 3.98 3.98 CP2 0.10 0.10 0.10

[0119] Table 7

[0120] In Example 3, the surface of the first lens near the human eye is concave, and the surface of the first lens near the display is convex. The surface of the second lens near the human eye is flat, and the surface of the second lens near the display is convex. The focal power of the third lens can be positive or negative, and the surface of the third lens near the human eye is concave, and the surface of the third lens near the display is convex.

[0121] In Example 3, 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 side surface of the first lens close to the display and the side surface of the second lens close to the human eye 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 side surface of the second lens close to the display and the side surface of the third lens close to the human eye 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.

[0122] Table 8 shows the basic structural parameter table of the optical system of Example 3, where the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0123]

[0124] Table 8

[0125] Table 9 shows the high-order coefficients that can be used for each aspheric surface in Example 3, where each aspheric surface shape can be defined by formula (1) given in Example 1 above.

[0126]

[0127] Table 9

[0128] Fig.17 The axial chromatic aberration curve of the optical system of Example 3 is shown, which indicates the deviation of the focal point of light of different wavelengths after passing through the optical system. Fig.18 An astigmatism curve of the optical system of Example 3 is shown, which indicates meridional field curvature and sagittal field curvature. Fig.19 The distortion curve of the optical system of Example 3 is shown, which represents the distortion magnitude values ​​corresponding to different field angles.

[0129] according to Figures 17 to 19 It can be seen that the optical system given in Example 3 can achieve good imaging quality.

[0130] In summary, Examples 1 to 3 respectively satisfy the relationships shown in Table 10.

[0131] Conditional / Example 1-1 1-2 1-3 2-1 2-2 2-3 3-1 3-2 3-3 FG1 / (CP1+EP12) 8.36 8.36 7.52 5.86 6.02 5.86 10.77 10.77 10.77 (D1s-d1s) / CT2 4.74 4.74 4.53 3.22 4.88 3.31 1.52 1.52 1.48 |R1| / (D1m-d1m) 381.75 345.89 345.89 191.57 36.63 209.35 53.35 53.35 58.92 (CT1*T12) / (EP12*CP2) 0.42 0.42 7.20 9.88 3.63 9.88 8.51 8.51 8.51 (d2s+D2s) / |R2| 3.40 3.40 3.41 3.44 3.44 3.43 2.80 2.80 2.79 (CT1+CT2) / EP12 2.45 2.45 2.05 3.08 1.13 3.08 4.72 4.72 4.72 (T12+T23) / CP2 1.14 1.14 23.70 17.40 17.40 17.40 14.35 14.35 14.35 |R4+R5| / (D2S+D2m) 2.63 2.63 2.55 49.53 49.53 49.80 1.00 1.00 1.00 (|R5|+|R6|) / (d2m+d2s) 2.49 2.49 2.53 5.88 5.88 5.88 1.62 1.62 1.62 |FG2| / (d2s+d2m) 1.92 1.92 1.95 97.16 97.16 97.16 0.97 0.97 0.97

[0132] Table 10

[0133] 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.

[0134] The present application also provides an imaging device, whose electronic photosensitive element can be a photosensitive coupled device (CCD) or a complementary metal oxide semiconductor element (CMOS). The imaging device can be an independent imaging device such as a digital camera, or an imaging module integrated in a mobile electronic device such as a mobile phone. The imaging device is equipped with the optical system described above.

[0135] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0136] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0137] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0138] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An optical system, characterized in that: The invention comprises a lens barrel and a first element group, a second element group and a third element group which are arranged in the lens barrel in sequence from the human eye side to the display side. The first element group includes at least a first lens; The second element group includes at least a second lens; The third element group includes at least a third lens; The optical system further comprises 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 against 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 against the second element group; The effective focal length FG1 of the first element group, the maximum thickness CP1 of the first spacing element, and the interval EP12 along the optical axis between the side surface of the first spacing element close to the display and the side surface of the second spacing element close to the human eye satisfy: 5.8 <FG1 / (CP1+EP12)<10.8。 2. The optical system according to claim 1, characterized in that The optical system also includes a reflective polarizing element and a quarter retardation plate, which are combined with the surface of the first lens close to the display side or the surface of the second lens close to the human eye side.

3. The optical system according to claim 1, characterized in that The outer diameter D1s of the first spacer element close to the side surface of the human eye, the inner diameter d1s of the first spacer element close to the side surface of the human eye and the center thickness CT2 of the second lens on the optical axis satisfy: 1.4<(D1s-d1s) / CT2<4.

9.

4. The optical system according to claim 1, characterized in that The curvature radius R1 of the first lens surface close to the human eye, the outer diameter D1m of the first spacing element surface close to the display side and the inner diameter d1m of the first spacing element surface close to the display side satisfy: 36.6<|R1| / (D1m-d1m)<381.

8.

5. The optical system according to claim 1, characterized in that The center thickness CT1 of the first lens on the optical axis, the distance T12 between the side surface of the first lens close to the display and the side surface of the second lens close to the human eye on the optical axis, the interval EP12 between the side surface of the first spacer element close to the display and the side surface of the second spacer element close to the human eye along the optical axis, and the center thickness CP2 of the second lens on the optical axis satisfy: 0.4<(CT1*T12) / (EP12*CP2)<9.

9.

6. The optical system according to claim 1, characterized in that The inner diameter d2s of the second spacer element's side surface close to the human eye, the outer diameter D2s of the second spacer element's side surface close to the human eye, and the curvature radius R2 of the first lens' side surface close to the display satisfy: 2.7<(d2s+D2s) / |R2|<3.

5.

7. The optical system according to claim 1, characterized in that The center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, and the interval EP12 along the optical axis between the side surface of the first spacing element close to the display and the side surface of the second spacing element close to the human eye satisfy: 1.1<(CT1+CT2) / EP12<4.

8.

8. The optical system according to claim 1, characterized in that The distance T12 between the side surface of the first lens close to the display and the side surface of the second lens close to the human eye on the optical axis, the distance T23 between the side surface of the second lens close to the display and the side surface of the third lens close to the human eye on the optical axis and the maximum thickness CP2 of the second spacer element satisfy: 1.1<(T12+T23) / CP2<23.

8.

9. The optical system according to claim 1, characterized in that The curvature radius R4 of the second lens close to the display surface, the curvature radius R5 of the third lens close to the side surface of the human eye, the outer diameter D2s of the second spacer element close to the side surface of the human eye and the outer diameter D2m of the second spacer element close to the side surface of the display satisfy: 0.9<|R4+R5| / (D2s+D2m)<50.

0.

10. The optical system according to claim 1, characterized in that The curvature radius R5 of the third lens's side surface close to the human eye, the curvature radius R6 of the third lens's side surface close to the display, the inner diameter d2m of the second spacer element's side surface close to the display, and the inner diameter d2s of the second spacer element's side surface close to the human eye satisfy: 1.6<(|R5|+|R6|) / (d2m+d2s)<5.9.

Images