Compensation imaging lens group and optical equipment
By optimizing the relationship between the radius of curvature, refractive index, and Abbe number of the lens group, the problem of low image sharpness of coaxial telecentric lenses was solved, and the image edge sharpness and color vividness were improved, thus enhancing the image quality.
Patent Information
- Application Number
- CN202520253160.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-18
- Publication Date
- 2025-11-25
- Estimated Expiration
- 2035-02-18
AI Technical Summary
Existing coaxial telecentric lenses have low image clarity and poor image quality in the optical path, especially with blurred image edges and inaccurate color reproduction.
A compensating imaging lens group is adopted, including a main lens group, a strong light reflecting mirror, a compensating plane mirror and six lens groups. By optimizing the relationship between the curvature radius, refractive index and Abbe number of the lenses, dispersion and coma are reduced, ensuring that the imaging positions of different wavelengths of light on the optical axis are consistent.
It significantly improves image edge sharpness and overall contrast, enhances image visual quality, reduces chromatic aberration and coma, and makes images sharper and more detailed.
Smart Images
Figure CN223597996U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to optical system technical field, especially relate to a kind of compensation imaging lens group and optical equipment. BACKGROUND
[0002] As a kind of precision optical element, coaxial telecentric lens plays a vital role in machine vision, scientific research and industrial production and many other fields. It is composed of multiple lenses, and the optical center of each lens is on the same straight line, which can make the image more clear and sharp, to enlarge the image and improve the resolution. It is composed of multiple lenses carefully calculated and arranged, to ensure that the optical center of each lens is strictly located on the same straight line, effectively reducing the distortion of light when passing through the lens, so that the final formed image is closer to the true form of object.
[0003] As Figure 1 And Figure 2 As shown in a kind of lens group of coaxial telecentric lens of prior art, including main lens group and reinforcing light reflector along the direction of light path, light will be curved and diffused when passing through lens group, causing the edge of image to become blurred, not only affecting the definition of image, but also reducing the accuracy of color restoration, so the definition of imaging is significantly reduced, and the imaging quality is reduced. UTILITY MODEL CONTENT
[0004] The utility model aims to provide a kind of compensation imaging lens group and optical equipment, to solve the problem of low imaging definition and poor imaging quality in the light path in prior art.
[0005] The technical scheme of the utility model is: a kind of compensation imaging lens group, comprising: main lens group, reinforcing light reflector, compensation plane mirror and six groups of lenses distributed in sequence along the direction of light path;
[0006] The six groups of lenses include:
[0007] The first lens is a concave lens with negative refractive power;
[0008] The second lens is a concave lens with negative refractive power;
[0009] The third lens is a concave lens with negative refractive power;
[0010] The fourth lens is a convex lens with positive refractive power;
[0011] The fifth lens is a concave lens with negative refractive power;
[0012] The sixth lens is a convex lens with positive refractive power;
[0013] The relationship that the curvature radiuses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens satisfy along the light path entrance end and exit end is:
[0014] 0.5 < |(R i+R i') / (R i-R i')| < 3.6, i=1, 2, 3, 4, 5, 6;
[0015] Wherein, R i is the curvature radius corresponding to the entrance end, and R i' is the curvature radius corresponding to the exit end.
[0016] Preferably, the refractive index and the Abbe number between the five groups of lenses satisfy the following relationship:
[0017] 0.8 < nd / nd i < 0.95, i=1, 2, 3, 4, 5, 6;
[0018] Wherein, nd is the refractive index of the compensation plane mirror;
[0019] nd 1, nd2, nd3, nd4, nd5, nd6 are the refractive indexes of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens respectively;
[0020] 1.2 < vd / vd i < 2.6, i=1, 2, 3, 4, 5, 6;
[0021] Wherein, vd is the Abbe number of the compensation plane mirror;
[0022] vd 1, vd2, vd3, vd4, vd5, vd6 are the Abbe numbers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens respectively.
[0023] Preferably, the thickness H of the compensation plane mirror satisfies: 7 < H < 7.5 mm;
[0024] In the six groups of lenses, the central thickness of each concave lens satisfies the relationship:
[0025] 0.5 < H / h i < 4; i=1, 2, 3, 5;
[0026] In the six groups of lenses, the central thickness of each convex lens satisfies the relationship:
[0027] 0.1 < H / h i < 0.5; i=4, 6;
[0028] Wherein, h1, h2, h3, h4, h5, h6 are the central thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens respectively.
[0029] Preferably, the third lens and the fourth lens constitute a double cemented lens group.
[0030] Preferably, the main lens comprises a first main lens and a second main lens, the first main lens is a convex lens, and the second main lens is a concave lens.
[0031] Preferably, the curvature radius of the first main lens at the light path incident end and the light path exit end satisfies the relationship of:
[0032] -0.16 < Rz1 / Rz1' < -0.23;
[0033] The curvature radius of the second main lens at the light path incident end and the light path exit end satisfies the relationship of:
[0034] 0.8 < Rz2 / Rz2' < 1.2;
[0035] Wherein, Rz1 is the curvature radius of the first main lens deviating from the light path incident end, Rz1' is the curvature radius of the first main lens deviating from the light path exit end, Rz2 is the curvature radius of the second main lens deviating from the light path incident end, and Rz2' is the curvature radius of the second main lens deviating from the light path exit end.
[0036] Preferably, the fifth lens and the sixth lens form a lens group, and the air gap between the fifth lens and the sixth lens is 2.1mm+5%.
[0037] The application also discloses an optical equipment comprising the compensation imaging lens group.
[0038] Compared with the prior art, the application has the following advantages:
[0039] (1) The application optimizes the on-axis chromatic aberration of the original lens group by adding the lens group, which means that the imaging positions of light rays of different wavelengths on the optical axis tend to be consistent, greatly reducing the dispersion phenomenon, and the system effectively improves the edge definition of imaging, so that the image edge is more sharp and the details are more clear. At the same time, the enhancement of the overall contrast also makes the image color more vivid and the level more distinct, thereby significantly improving the visual quality of the image.
[0040] (2) The lens group of the application also optimizes the coma of the original lens group. The optimized system makes the point light source imaging of the image edge more sharp, and the tailing phenomenon is greatly reduced, thereby significantly improving the imaging definition of the edge region. Not only does it make the edge details of the image more clear and identifiable, but also enhances the overall contrast and level of imaging, providing the observer with a more real and delicate visual experience. The optimized system has a significantly reduced coma, and the stability of the optical path is significantly improved, so that the imaging quality is more reliable and consistent. BRIEF DESCRIPTION OF DRAWINGS
[0041] The utility model is further described below in combination with the drawings and examples:
[0042] Figure 1 It is the structure schematic diagram of main lens group of prior art;
[0043] Figure 2 It is the MTF graph of coaxial imaging optical system of main lens group of prior art;
[0044] Figure 3 It is the structure schematic diagram of compensating imaging lens group of the utility model;
[0045] Figure 4 It is the MTF graph of coaxial imaging optical system of compensating imaging lens group of the utility model.
[0046] Explanation of reference signs:
[0047] 1, main lens group;11, first main body is transparent;12, second main body is transparent;2, strong light reflecting mirror;3, six groups of lenses;31, first lens;32, second lens;33, third lens;34, fourth lens;35, fifth lens;36, sixth lens;4, compensating plane mirror. DETAILED DESCRIPTION
[0048] In order to make the purpose, technical scheme and advantage of the utility model more clear, the following will combine the utility model specific embodiment and corresponding drawing to make the utility model technical scheme clear, complete description. Obviously, the described embodiment is only a part of the utility model embodiment, not all embodiments. Based on the embodiment in the utility model, all other embodiments obtained by the person skilled in the art without making creative labor are within the protection scope of the utility model.
[0049] The embodiment of the utility model is described in detail below, and the examples of the embodiment are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary, only for explaining the utility model, and cannot be understood as limiting the utility model.
[0050] In the description of the utility model, it is understood that the orientation or position relationship indicated by the terms "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or position relationship shown in the drawings, only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as limiting the utility model.
[0051] A compensation imaging lens group, comprising a main lens group 1, a strong light reflecting mirror 2, a compensation plane mirror 4 and six lens groups 3 arranged in sequence along the light path direction;
[0052] Regarding the main lens group 1:
[0053] As shown in Figure 1 and Figure 2 , the main lens group 1 comprises a first main lens 11 and a second main lens 12, the first main lens 11 is a convex lens, and the second main lens 12 is a concave lens,
[0054] The curvature radii of the first main lens 11 along the light path incident end and the exit end satisfy the relationship:
[0055] -0.16 < Rz1 / Rz1' < -0.23;
[0056] The curvature radii of the second main lens 12 along the light path incident end and the exit end satisfy the relationship:
[0057] 0.8 < Rz2 / Rz2' < 1.2;
[0058] Wherein, Rz1 is the curvature radius of the first main lens 11 deviating from the light path incident end, Rz1' is the curvature radius of the first main lens 11 deviating from the light path exit end; Rz2 is the curvature radius of the second main lens 12 deviating from the light path incident end, Rz2' is the curvature radius of the second main lens 12 deviating from the light path exit end.
[0059] Specifically, in the embodiment, the first main lens 11 is made of C7980, the curvature radius of the first main lens 11 deviating from the light path incident end is 180.370mm, the curvature radius of the first main lens 11 deviating from the light path exit end is -908.270mm, and the center thickness of the first main lens 11 is 12mm.
[0060] The second main lens 12 is made of C7980, the curvature radius of the second main lens 12 deviating from the light path incident end is -141.538mm, the curvature radius of the second main lens 12 deviating from the light path exit end is -154.678mm, and the center thickness of the second main lens 12 is 11.938mm.
[0061] The strong light reflecting mirror 2 is made of SAPPHIRE, with a thickness of 7mm; the material has low heat absorption coefficient and small deformation under high temperature, and its surface is adhered with a coating, which has a reflectivity of 99.99% for 1070nm wavelength light and a transmittance of more than 80% for visible light.
[0062] Regarding the compensation plane mirror 4:
[0063] The main reason is that the dispersion in the X and Y directions of the front optical path corresponding to the main lens group 11 is quite different. The addition of the compensating plane mirror 42 makes the dispersion in the X and Y directions more consistent.
[0064] The thickness H of the compensating plane mirror 4 satisfies: 7 < H < 7.5 mm; specifically, the thickness of the compensating plane mirror 4 is 7.19 mm.
[0065] Its refractive index and Abbe number range satisfy the following:
[0066] 1.42<nd<1.45, 93.5<vd<0.96.4
[0067] In this embodiment, the compensating plane mirror 4 is made of H-FK95N material.
[0068] Regarding the six groups of lenses 3:
[0069] like Figure 3 and Figure 4 As shown, the six lens groups 3 include a first lens 31, a second lens 32, a third lens 33, a fourth lens 34, a fifth lens 35, and a sixth lens 36.
[0070] Among them, the first lens 31 is a concave lens with negative refractive power; the second lens 32 is a concave lens with negative refractive power; the third lens 33 is a concave lens with negative refractive power; the fourth lens 34 is a convex lens with positive refractive power; the fifth lens 35 is a concave lens with negative refractive power; and the sixth lens 36 is a convex lens with positive refractive power.
[0071] The refractive indices of the six lenses (group 3) satisfy the following relationship:
[0072] 0.8<nd / nd i<0.95, i=1, 2, 3, 4, 5, 6;
[0073] Where nd is the refractive index of the compensating plane mirror 4;
[0074] nd1, nd2, nd3, nd4, nd5, and nd6 are the refractive indices of the first lens 31, the second lens 32, the third lens 33, the fourth lens 34, the fifth lens 35, and the sixth lens 36, respectively.
[0075] More specifically,
[0076] 0.84 < nd / nd1 < 0.9
[0077] 0.9 < nd / nd2 < 0.95
[0078] 0.85 < nd / nd3 < 0.93
[0079] 0.89 < nd / nd4 < 0.94
[0080] 0.85 < nd / nd5 < 0.93,
[0081] 0.78 < nd / nd6 < 0.85.
[0082] The Abbe numbers between the six groups of lenses 3 satisfy the following relationship:
[0083] 1.2 < vd / vd i < 2.6, i = 1, 2, 3, 4, 5, 6;
[0084] wherein vd is the Abbe number of the compensating flat mirror 4;
[0085] vd1, vd2, vd3, vd4, vd5, vd6 are the Abbe numbers of the first lens 31, the second lens 32, the third lens 33, the fourth lens 34, the fifth lens 35, and the sixth lens 36, respectively.
[0086] More specifically,
[0087] 1.5 < vd / vd1 < 1.65,
[0088] 1.3 < vd / vd2 < 1.42,
[0089] 1.9 < vd / vd3 < 2.2,
[0090] 1.3 < vd / vd4 < 1.4,
[0091] 2.5 < vd / vd5 < 2.58,
[0092] 1.8 < vd / vd6 < 2.
[0093] Since the refractive index and the Abbe number belong to the material specifications, which are determined by the selection of the specific lens, in the present embodiment, the first lens 31 is selected from the material H-LAK4L; the second lens 32 and the rear lens are selected from H-ZPK7; the third lens 33 is selected from the material H-TF3L; the fourth lens 34 is selected from the material H-ZPK7, the fifth lens 35 is selected from the material F2; and the sixth lens 36 is selected from the material H-LAF50B.
[0094] The curvature radii of the first lens 31, the second lens 32, the third lens 33, the fourth lens 34, the fifth lens 35, and the sixth lens 36 along the incident end and the exit end of the optical path satisfy the following relationship:
[0095] 0.5 < |(R i+R i’) / (R i-R i’)| < 3.6, i = 1, 2, 3, 4, 5, 6;
[0096] wherein R i is the curvature radius corresponding to the incident end, and R i’ is the curvature radius corresponding to the exit end.
[0097] More specifically, in the present embodiment, the radius of curvature of the six groups of lenses 3 is as follows,
[0098] The incident end radius of curvature of the first lens 31 is 165.074 mm, and the exit end radius of curvature of the first lens 31 is 43.02 mm; the incident end radius of curvature of the second lens 32 is 356.263 mm, and the exit end radius of curvature of the second lens 32 is -80.197 mm; the incident end radius of curvature of the third lens 33 is 191.165 mm, and the exit end radius of curvature of the third lens 33 is 37.49 mm; the incident end radius of curvature of the fourth lens 34 is 37.49 mm, and the exit end radius of curvature of the fourth lens 34 is 106.662 mm; the incident end radius of curvature of the fifth lens 35 is 65.051 mm, and the exit end radius of curvature of the fifth lens 35 is 33.814 mm; the incident end radius of curvature of the sixth lens 36 is 35.555 mm, and the exit end radius of curvature of the sixth lens 36 is 136.506 mm.
[0099] In the six groups of lenses 3, the central thickness of each concave lens satisfies the relationship:
[0100] 0.5 < H / h i < 4; i = 1, 2, 3, 5;
[0101] In the six groups of lenses 3, the central thickness of each convex lens satisfies the relationship:
[0102] 0.1 < H / h i < 0.5; i = 4, 6;
[0103] wherein h1, h2, h3, h4, h5, h6, respectively, are the central thicknesses of the first lens 31, the second lens 32, the third lens 33, the fourth lens 34, the fifth lens 35, and the sixth lens 36.
[0104] Specifically, the central thickness of the first lens 31 is 3.6 mm; the central thickness of the second lens 32 is 0.62 mm; the central thickness of the third lens 33 is 3.6 mm; the central thickness of the fourth lens 34 is 0.46 mm; the central thickness of the fifth lens 35 is 1.1 mm; and the central thickness of the sixth lens 36 is 0.108 mm.
[0105] The fifth lens 35 and the sixth lens 36 constitute a lens group, and more specifically, a double cemented lens group is formed between the fifth lens 35 and the sixth lens 36, and the air gap between the fifth lens 35 and the sixth lens 36 is 2.1 mm + 5%.
[0106] A compensation imaging lens group according to the present application, A is the Seidel coefficient evaluation of the optical path of the main lens group, B is the Seidel coefficient evaluation after the main lens group is added with the six groups of lenses 3:
[0107] Table 1. Seidel coefficient evaluation
[0108] spherical aberration coma astigmatism field curvature distortion on-axis chromatic aberration off-axis chromatic aberration A 0.000016 0.001320 0.000366 0.000289 0.000008 -0.026229 -0.000187 B 0.001556 0.000201 -0.000013 0.000396 0.002677 0.000341 0.000326
[0109] After the optimization adjustment of the system, although the performance of the spherical aberration and the sagittal chromatic aberration is sacrificed to a certain extent, the optimization range of the axial chromatic aberration and the coma is extremely significant. Specifically, the axial chromatic aberration of A is-0.026229, and the absolute value is large, indicating that the imaging positions of different wavelengths of light on the axis are different, resulting in blurred imaging (especially in the edge area). The axial chromatic aberration of B is 0.000341, and the absolute value is much smaller than that of the A main lens group, indicating that the imaging positions of different wavelengths of light on the axis are almost the same. The optimization of the axial chromatic aberration significantly reduces the chromatic dispersion phenomenon, greatly improves the edge definition and overall contrast of the imaging, and significantly improves the image detail performance.
[0110] The absolute value of the coma of A is large, resulting in a comet-like tail of off-axis point light source imaging, affecting the imaging definition. The absolute value of the coma of B is much smaller than that of A, and the optimization of the coma significantly improves the off-axis imaging quality, so that the imaging of the point light source at the edge of the image is more sharp, the tail phenomenon is reduced, and the imaging definition of the edge area is significantly improved.
[0111] The sacrifice of the spherical aberration can be partially compensated by other optical design methods (such as aspherical lenses), so this sacrifice is acceptable within a certain range; the sacrifice of the sagittal chromatic aberration can be partially eliminated by post-processing (such as digital correction), so this sacrifice is also acceptable within a certain range.
[0112] Based on the above, the application also discloses an optical device comprising the compensation imaging lens group. The application can be used in a high-energy laser system and is coaxial with the light emitting path. Compared with an external light adjusting axis of a camera, the coaxial light path greatly reduces the workload and failure rate. The above embodiments are only for illustrating the technical concept and characteristics of the application, and the purpose is to enable those skilled in the art to understand the content of the application and implement it, and cannot limit the protection scope of the application. For those skilled in the art, it is obvious that the application is not limited to the details of the above exemplary embodiments, and the application can be implemented in other specific forms without departing from the spirit or basic characteristics of the application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the application.
Claims
1. A compensating imaging lens group, characterized by, The application relates to a lens, which comprises: a main lens group, a strong light reflecting mirror, a compensation plane mirror and six lens groups arranged in sequence along the light path direction; the six lens groups comprise: a first lens which is a concave lens with negative refractive power; a second lens which is a concave lens with negative refractive power; a third lens which is a concave lens with negative refractive power; a fourth lens which is a convex lens with positive refractive power; a fifth lens which is a concave lens with negative refractive power; a sixth lens which is a convex lens with positive refractive power; the curvature radii of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens along the light path incident end and the light path emission end satisfy the following relationship: 0.5 < |(Ri+Ri') / (Ri-Ri')| < 3.6, i=1, 2, 3, 4, 5, 6; wherein Ri is the curvature radius corresponding to the incident end, and Ri' is the curvature radius corresponding to the emission end.
2. A compensating imaging lens group according to claim 1, characterized in that: the refractive index and the Abbe number between the five lens groups satisfy the following relationship: 0.8 < nd / ndi < 0.95, i=1, 2, 3, 4, 5, 6; wherein nd is the refractive index of the compensation plane mirror; nd1, nd2, nd3, nd4, nd5 and nd6 are the refractive indexes of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens respectively; 1.2 < vd / vdi < 2.6, i=1, 2, 3, 4, 5, 6; wherein vd is the Abbe number of the compensation plane mirror; vd1, vd2, vd3, vd4, vd5 and vd6 are the Abbe numbers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens respectively.
3. A compensating imaging lens group according to claim 2, characterized in that: the thickness H of the compensation plane mirror satisfies 7 < H < 7.5 mm; in the six lens groups, the central thickness of each concave lens satisfies the following relationship: 0.5 < H / hi < 4; i=1, 2, 3, 5; in the six lens groups, the central thickness of each convex lens satisfies the following relationship: 0.1 < H / hi < 0.5; i=4, 6; wherein h1, h2, h3, h4, h5 and h6 are the central thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens respectively.
4. A compensating imaging lens group according to claim 3, characterized in that: the third lens and the fourth lens form a double cemented lens group.
5. The compensating imaging lens set of claim 1, wherein: the main lens comprises a first main lens and a second main lens, the first main lens is a convex lens, and the second main lens is a concave lens.
6. A compensating imaging lens group according to claim 5, characterized in that: the curvature radii of the first main lens along the light path incident end and the light path emission end satisfy the following relationship: -0.16 < Rz1 / Rz1' < -0.23; the curvature radii of the second main lens along the light path incident end and the light path emission end satisfy the following relationship: 0.8 < Rz2 / Rz2' < 1.2; wherein Rz1 is the curvature radius of the first main lens towards the light path incident end, Rz1' is the curvature radius of the first main lens towards the light path emission end, Rz2 is the curvature radius of the second main lens towards the light path incident end, and Rz2' is the curvature radius of the second main lens towards the light path emission end.
7. The compensating imaging lens set of claim 1, wherein: the fifth lens and the sixth lens form a lens group, and the air gap between the fifth lens and the sixth lens is 2.1 mm+5%.
8. An optical device, characterized by: A compensation imaging lens group comprising any one of claims 1-7.