Teleconverter lens

Abstract

The invention discloses a teleconverter lens. The teleconverter lens comprises a system front group and a system rear group, the system front group comprises a first lens group and a second lens group, and the system rear group comprises a third lens group and a fourth lens group; the first lens group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged from the object plane to the image plane along the optical axis; the second lens group comprises a sixth lens, a seventh lens, an eighth lens and a ninth lens which are sequentially arranged from the object plane to the image plane along the optical axis; the third lens group comprises a tenth lens and an eleventh lens which are sequentially arranged from the object plane to the image plane along the optical axis; the fourth lens group comprises a twelfth lens and a thirteenth lens; the focal length fz1 of the first lens group and the focal length fz2 of the second lens group satisfy 0.8200 lt; fz1 / fz2lt; the focal length fz3 of the third lens group and the focal length fz4 of the fourth lens group satisfy 1.6800 lt; fz3 / fz4lt; and 7.3000). Therefore, the lengths of front and back groups of the system can be reduced, the total length of the system is less than 120mm, and the characteristic of short total length of the system is achieved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of optical devices, and in particular to a teleconverter lens. Background Art

[0002] With the development of society, smartphones have become increasingly popular due to their portability and powerful camera functions. However, the limited size of mobile phones has limited the application of mobile phone lenses in photography. To address this problem, a growing number of external lenses compatible with mobile phones have emerged on the market as auxiliary lenses to meet the diverse needs of photography functions and applications.

[0003] At present, the external detachable lenses on the market that are installed on the built-in lens of the mobile phone to improve the imaging quality of the mobile phone are relatively large in size and still cannot meet the usage needs of users. Summary of the Invention

[0004] The present invention provides a teleconverter lens, which realizes a teleconverter lens with a small size and high image quality by reasonably setting the number and combination of lenses and the focal length matching between different lens groups.

[0005] An embodiment of the present invention provides a teleconverter lens, comprising a system front group and a system rear group arranged in sequence from an object plane to an image plane along an optical axis;

[0006] The front lens group includes a first lens group and a second lens group arranged in sequence from the object plane to the image plane along the optical axis, and the rear lens group includes a third lens group and a fourth lens group arranged in sequence from the object plane to the image plane along the optical axis;

[0007] The first lens group includes a first lens, a second lens, a third lens, a fourth lens and a fifth lens arranged in sequence from the object plane to the image plane along the optical axis;

[0008] The second lens group includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged in sequence from the object plane to the image plane along the optical axis;

[0009] The third lens group includes a tenth lens and an eleventh lens arranged in sequence from the object plane to the image plane along the optical axis;

[0010] The fourth lens group includes a twelfth lens and a thirteenth lens arranged in sequence from the object plane to the image plane along the optical axis;

[0011] Wherein, the focal length of the first lens group is f z1 , the focal length of the second lens group is f z2 , the focal length of the third lens group is f z3 , the focal length of the fourth lens group is f z4 ;

[0012] Among them, 0.8200 <f z1 / f z2 <1.2700, 1.6800 <f z3 / f z4 <7.3000.

[0013] Optionally, the combined focal length of the front group of the system is f1, and the combined focal length of the rear group of the system is f2;

[0014] Among them, 2.1100 <f1 / f2<2.5900。

[0015] Optionally, the first lens is a positive power lens, the second lens is a negative power lens, the third lens is a positive power lens, the fourth lens is a negative power lens, the fifth lens is a positive power lens, the sixth lens is a positive power lens, the seventh lens is a positive power lens, the eighth lens is a negative power lens, the ninth lens has power, the tenth lens is a negative power lens, the eleventh lens is a positive power lens, the twelfth lens is a positive power lens, and the thirteenth lens is a positive power lens.

[0016] Optionally, the object side sag of the first lens is SAG11, the image side sag of the fifth lens is SAG25, and the object side sag of the tenth lens is SAG1 10 The image side sagittal height of the eleventh lens is SAG2 11 The object side sag height of the twelfth lens is SAG1 12 The image side sagittal height of the thirteenth lens is SAG2 13 ;

[0017] Among them, -0.5800 <SAG11 / SAG25<-0.3500,0.0500<SAG1 10 / SAG2 11 <0.2400, 1.0000 <SAG1 12 / SAG2 13 <2.5500.

[0018] Optionally, the object side sag height of the first lens is SAG11, the object side sag height of the sixth lens is SAG16, and the object side sag height of the tenth lens is SAG1 10 The image side sagittal height of the eleventh lens is SAG2 11 The object side sag height of the twelfth lens is SAG1 12 The image side sagittal height of the thirteenth lens is SAG2 13 ;

[0019] Among them, 0.3200 <SAG11 / SAG16<0.5100,0.0400<SAG1 10 / SAG1 12 <0.5700, 1.6500 <SAG2 11 / SAG2 13 <3.2200.

[0020] Optionally, the Abbe number of the first lens is vd1, the Abbe number of the second lens is vd2, the Abbe number of the third lens is vd3, the Abbe number of the fourth lens is vd4, and the refractive index of the fifth lens is nd5;

[0021] Of these, 51,000 <vd1<98.000,1.000<vd2<42.000,40.000<vd3<98.000,24.000<vd4<52.000,1.6500<nd5<2.0000。

[0022] Optionally, the refractive index of the sixth lens is nd6, the refractive index of the seventh lens is nd7, the refractive index of the eighth lens is nd8, and the refractive index of the ninth lens is nd9;

[0023] Among them, 1.6600 <nd6<2.0000,1.5000<nd7<1.8700,1.6600<nd8<2.000,1.4800<nd9<2.000。

[0024] Optionally, the Abbe number of the tenth lens is vd10, and the Abbe number of the eleventh lens is vd11;

[0025] Of these, 17,000 <vd10<40.000,45.000<vd11<77.000。

[0026] Optionally, the refractive index of the twelfth lens is nd12, and the Abbe number of the thirteenth lens is vd13;

[0027] Among them, 1.4900 <nd12<2.0000,35.000<vd13<75.000。

[0028] Optionally, the seventh lens and the eighth lens are cemented together.

[0029] Optionally, the first lens includes a first object-side surface close to the object plane and a first image-side surface close to the image plane, the first object-side surface is a convex surface, and the first image-side surface is a convex surface;

[0030] The second lens includes a second object-side surface close to the object plane and a second image-side surface close to the image plane, the second object-side surface is concave, and the second image-side surface is convex;

[0031] The third lens comprises a third object-side surface close to the object plane and a third image-side surface close to the image plane, the third object-side surface is a convex surface, and the third image-side surface is a convex surface;

[0032] The fourth lens comprises a fourth object-side surface close to the object plane and a fourth image-side surface close to the image plane, the fourth object-side surface is concave, and the fourth image-side surface is concave;

[0033] The fifth lens comprises a fifth object-side surface close to the object plane and a fifth image-side surface close to the image plane, the fifth object-side surface is concave, and the fifth image-side surface is convex;

[0034] The sixth lens comprises a sixth object-side surface close to the object plane and a sixth image-side surface close to the image plane, the sixth object-side surface is convex, and the sixth image-side surface is concave;

[0035] The seventh lens element includes a seventh object-side surface close to the object plane and a seventh image-side surface close to the image plane, the seventh object-side surface is a convex surface, and the seventh image-side surface is a convex surface;

[0036] The eighth lens comprises an eighth object-side surface close to the object plane and an eighth image-side surface close to the image plane, the eighth object-side surface is concave, and the eighth image-side surface is concave;

[0037] The ninth lens comprises a ninth object-side surface close to the object plane and a ninth image-side surface close to the image plane, wherein the ninth object-side surface is concave and the ninth image-side surface is convex.

[0038] The tenth lens comprises a tenth object-side surface close to the object plane and a tenth image-side surface close to the image plane, the tenth object-side surface is concave, and the tenth image-side surface is concave;

[0039] The eleventh lens includes an eleventh object-side surface close to the object plane and an eleventh image-side surface close to the image plane, the eleventh object-side surface is a convex surface, and the eleventh image-side surface is a convex surface;

[0040] The twelfth lens comprises a twelfth object-side surface close to the object plane and a twelfth image-side surface close to the image plane, the twelfth object-side surface is concave, and the twelfth image-side surface is convex;

[0041] The thirteenth lens includes a thirteenth object-side surface close to the object plane and a thirteenth image-side surface close to the image plane. The thirteenth object-side surface is a convex surface, and the thirteenth image-side surface is a convex surface.

[0042] Optionally, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, the twelfth lens and the thirteenth lens are all glass spherical lenses.

[0043] Optionally, the teleconverter lens further includes a stop, and the stop is arranged on the image side surface of the thirteenth lens.

[0044] In the teleconverter lens provided in an embodiment of the present invention, the optical power distribution within the front and rear lens groups of the system affects the overall length of the system. By controlling the focal length ratio between the first and second lens groups in the front lens group, as well as the focal length ratio between the third and fourth lens groups in the rear lens group, the length of the front and rear lens groups can be reduced, reducing the total system length to less than 120 mm, achieving a short overall system length and improving the portability of the lens.

[0045] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0047] Figure 1 1 is a structural schematic diagram of a teleconverter lens provided in Embodiment 1 of the present invention;

[0048] Figure 2 1 is a schematic diagram of a spherical aberration curve of a teleconverter lens provided in Example 1 of the present invention;

[0049] Figure 3 1 is a schematic diagram of a vertical axis chromatic aberration curve of a teleconverter lens provided in Example 1 of the present invention;

[0050] Figure 4 1 is a schematic diagram of a distortion curve of a teleconverter lens provided in Example 1 of the present invention;

[0051] Figure 51 is a schematic diagram of an MTF curve of a teleconverter lens provided in Example 1 of the present invention;

[0052] Figure 6 1 is a structural schematic diagram of a teleconverter lens provided in a second embodiment of the present invention;

[0053] Figure 7 Schematic diagram of a spherical aberration curve of a teleconverter lens provided in the second embodiment of the present invention;

[0054] Figure 8 1 is a schematic diagram of a vertical axis chromatic aberration curve of a teleconverter lens provided in the second embodiment of the present invention;

[0055] Figure 9 1 is a schematic diagram of a distortion curve of a teleconverter lens provided in the second embodiment of the present invention;

[0056] Figure 10 1 is a schematic diagram of an MTF curve of a teleconverter lens provided in Example 2 of the present invention;

[0057] Figure 11 1 is a schematic structural diagram of a teleconverter lens provided in a third embodiment of the present invention;

[0058] Figure 12 Schematic diagram of a spherical aberration curve of a teleconverter lens provided in the third embodiment of the present invention;

[0059] Figure 13 1 is a schematic diagram of a vertical axis chromatic aberration curve of a teleconverter lens provided in Example 3 of the present invention;

[0060] Figure 14 1 is a schematic diagram of a distortion curve of a teleconverter lens provided in Example 3 of the present invention;

[0061] Figure 15 Schematic diagram of the MTF curve of a teleconverter lens provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0062] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0063] Example 1

[0064] Figure 1 FIG. 1 is a structural diagram of a teleconverter lens provided in the first embodiment of the present invention. Figure 1As shown, the teleconverter provided by the embodiment of the present invention includes a front lens group G1 and a rear lens group G2 arranged in sequence along the optical axis from the object plane to the image plane; the front lens group G1 includes a first lens group S1 and a second lens group S2 arranged in sequence along the optical axis from the object plane to the image plane, and the rear lens group G2 includes a third lens group S3 and a fourth lens group S4 arranged in sequence along the optical axis from the object plane to the image plane; the first lens group S1 includes a first lens 101, a second lens 102, and a third lens 103 arranged in sequence along the optical axis from the object plane to the image plane , fourth lens 104 and fifth lens 105; the second lens group S2 includes a sixth lens 106, a seventh lens 107, an eighth lens 108 and a ninth lens 109 arranged in sequence along the optical axis from the object plane to the image plane; the third lens group S3 includes a tenth lens 110 and an eleventh lens 111 arranged in sequence along the optical axis from the object plane to the image plane; the fourth lens group S4 includes a twelfth lens 112 and a thirteenth lens 113 arranged in sequence along the optical axis from the object plane to the image plane; wherein the focal length of the first lens group S1 is f z1 , the focal length of the second lens group S2 is f z2 , the focal length of the third lens group S3 is f z3 , the focal length of the fourth lens group S4 is f z4 ; Among them, 0.8200 <f z1 / f z2 <1.2700, 1.6800 <f z3 / f z4 <7.3000.

[0065] Specifically, the teleconverter provided by an embodiment of the present invention includes a front lens group G1 and a rear lens group G2 arranged along the optical axis. Furthermore, the front lens group G1 includes a first lens group S1 and a second lens group S2, and the rear lens group G2 includes a third lens group S3 and a fourth lens group S4. The first lens group S1 further includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, and a fifth lens 105. The second lens group S2 includes a sixth lens 106, a seventh lens 107, an eighth lens 108, and a ninth lens 109. In other words, the front lens group G1 includes the first to ninth lenses 101 to 109. The third lens group S3 includes a tenth lens 110 and an eleventh lens 111. The fourth lens group S4 includes a twelfth lens 112 and a thirteenth lens 113. In other words, the rear lens group G2 includes the tenth to thirteenth lenses 110 to 113. By reasonably setting the lens combination method in the front group and the rear group of the system, the number of lenses in the optical system is ensured to be set reasonably. The lens volume will not be larger due to too many lenses, and the aberration of a single lens due to the large optical focal length due to too few lenses will not be larger. While ensuring the miniaturization of the optical system, the imaging aberration is small and the imaging quality is high.

[0066] Furthermore, since the distribution of the optical power within the front group G1 and the rear group G2 of the system affects the overall length of the system, the ratio of the focal length fz1 of the first lens group S1 to the focal length fz2 of the second lens group S2 satisfies 0.8200 < fz1 / fz2 < 1.2700, and the ratio of the focal length fz3 of the third lens group S3 to the focal length fz4 of the fourth lens group S4 satisfies 1.6800 < fz3 / fz4 < 7.3000. By controlling the ratio of the focal lengths of the first lens group S1 and the second lens group S2 in the front group G1 of the system and the ratio of the focal lengths of the third lens group S3 and the fourth lens group S4 in the rear group G2 of the system, the lengths of the front and rear groups of the system can be reduced, making the overall length of the system less than 120 mm, achieving the characteristic of a short overall length of the system, and improving the portability of the lens.

[0067] Based on the above embodiments, the combined focal length of the front group G1 of the system is f1, and the combined focal length of the rear group G2 of the system is f2; wherein, 2.1100 < f1 / f2 < 2.5900. By controlling the ratio of the focal lengths of the front group G1 and the rear group G2 of the system, the magnification of the teleconverter lens can be improved, and finally the magnification of the teleconverter lens reaches more than 2×, meeting the application requirements.

[0068] Based on the above embodiments, the first lens 101 is a positive-power lens, the second lens 102 is a negative-power lens, the third lens 103 is a positive-power lens, the fourth lens 104 is a negative-power lens, the fifth lens 105 is a positive-power lens, the sixth lens 106 is a positive-power lens, the seventh lens 107 is a positive-power lens, the eighth lens 108 is a negative-power lens, the ninth lens 109 has optical power, the tenth lens 110 is a negative-power lens, the eleventh lens 111 is a positive-power lens, the twelfth lens 112 is a positive-power lens, and the thirteenth lens 113 is a positive-power lens.

[0069] Specifically, further, the optical focal length is equal to the difference between the convergence degree of the image plane light beam and the convergence degree of the object plane light beam, which characterizes the ability of the optical system to deflect light. The larger the absolute value of the optical focal length, the stronger the ability to bend light, and the smaller the absolute value of the optical focal length, the weaker the ability to bend light. When the optical focal length is a positive number, the refraction of light is convergent; when the optical focal length is a negative number, the refraction of light is divergent. The optical focal length can be applied to characterize a certain refractive surface of a lens (i.e., a surface of a lens), can be applied to characterize a certain lens, and can also be applied to characterize a system formed by multiple lenses (i.e., a lens group). In an embodiment of the present invention, the first lens 101 is a positive optical focal length lens, and its positive optical focal length setting can significantly correct the edge aberration of the optical imaging system, thereby improving the imaging resolution of the optical system. The second lens 102 is a negative optical focal length lens, and its negative optical focal length setting can effectively deflect the outgoing light, which is conducive to the design of a large image surface. Furthermore, the third lens 103 is a positive power lens, the fourth lens 104 is a negative power lens, the fifth lens 105 is a positive power lens, the sixth lens 106 is a positive power lens, the seventh lens 107 is a positive power lens, the eighth lens 108 is a negative power lens, the ninth lens 109 can be either a positive or negative power lens, the tenth lens 110 is a negative power lens, the eleventh lens 111 is a positive power lens, the twelfth lens 112 is a positive power lens, and the thirteenth lens 113 is a positive power lens. The variation in the positive and negative power of adjacent lenses can optimize the chromatic aberration and spherical aberration of the system, and the power of adjacent lenses with the same sign can disperse the aberrations carried by a single lens, ultimately giving the lens high image quality.

[0070] On the basis of the above embodiment, the object side sag of the first lens 101 is SAG11, the image side sag of the fifth lens 105 is SAG25, and the object side sag of the tenth lens 110 is SAG1 10 , the image side sagittal height of the eleventh lens 111 is SAG2 11 The object side sag height of the twelfth lens 112 is SAG1 12 The image side sagittal height of the thirteenth lens 113 is SAG2 13 ;in,

[0071] -0.5800 <SAG11 / SAG25<-0.3500,0.0500<SAG1 10 / SAG2 11 <0.2400,

[0072] 1.0000 <SAG1 12 / SAG2 13 <2.5500.

[0073] Specifically, the object plane of the first lens 101 is the first object plane in the first lens group S1, and the image plane of the fifth lens 105 is the last image plane in the first lens group S1. Similarly, the object plane of the tenth lens 110 is the first object plane in the third lens group S3, and the image plane of the eleventh lens 111 is the last image plane in the third lens group S3. The object plane of the twelfth lens 112 is the first object plane in the fourth lens group S4, and the image plane of the thirteenth lens 113 is the last image plane in the fourth lens group S4. The certain sagittal height relationship between the front and rear ends of a lens group reflects the aberrations borne by each lens group. By controlling these parameters, it is beneficial to optimize the overall aberrations within the single lens group and improve the image quality of the teleconverter.

[0074] On the basis of the above embodiment, the object side sag height of the first lens 101 is SAG11, the object side sag height of the sixth lens 106 is SAG16, and the object side sag height of the tenth lens 110 is SAG1 10 , the image side sagittal height of the eleventh lens 111 is SAG2 11 The object side sag height of the twelfth lens 112 is SAG1 12 The image side sagittal height of the thirteenth lens 113 is SAG2 13 ; Among them, 0.3200 <SAG11 / SAG16<0.5100,0.0400<SAG1 10 / SAG1 12 <0.5700, 1.6500 <SAG2 11 / SAG2 13 <3.2200.

[0075] Specifically, the object plane of the first lens 101 is the first object plane in the first lens group S1, the object plane of the sixth lens 106 is the first object plane in the second lens group S2, the object plane of the tenth lens 110 is the first object plane in the third lens group S3, the object plane of the twelfth lens 112 is the first object plane in the fourth lens group S4, the image plane of the eleventh lens 111 is the last image plane in the third lens group S3, and the image plane of the thirteenth lens 113 is the last image plane in the fourth lens group S4. A certain sagittal height relationship between lens groups reflects the structural similarity of each lens group. Similar structures can share the aberrations borne by each lens group. By controlling these parameters, the overall distortion of the system is optimized, keeping the distortion of the teleconverter within 0.5%.

[0076] Based on the above embodiments, the Abbe number of the first lens 101 is vd1, the Abbe number of the second lens 102 is vd2, the Abbe number of the third lens 103 is vd3, the Abbe number of the fourth lens 104 is vd4, and the refractive index of the fifth lens is nd5; where 51.000 < vd1 < 98.000, 1.000 < vd2 < 42.000, 40.000 < vd3 < 98.000, 24.000 < vd4 < 52.000, 1.6500 < nd5 < 2.0000. A certain Abbe value of the first lens group S1 can well control the chromatic dispersion of object-side light rays after entering the optical system, which is beneficial to reducing the axial chromatic aberration of the system. Further setting the refractive index of the fifth lens 105 satisfies

[0077] 1.6500 < nd5 < 2.0000, which is beneficial to reducing the spherical aberration and sine aberration of the first lens group S1, thereby improving the overall resolution of the system.

[0078] Based on the above embodiments, the refractive index of the sixth lens 106 is nd6, the refractive index of the seventh lens 107 is nd7, the refractive index of the eighth lens 108 is nd8, and the refractive index of the ninth lens 109 is nd9; where 1.6600 < nd6 < 2.0000, 1.5000 < nd7 < 1.8700, 1.6600 < nd8 < 2.000, 1.4800 < nd9 < 2.000. By restricting the refractive indices of the lenses within the second lens group S2, the off-axis field aberrations can be well controlled, which is beneficial to improving the image quality of the off-axis field of the system.

[0079] Based on the above embodiments, the Abbe number of the tenth lens 110 is vd10, and the Abbe number of the eleventh lens 111 is vd11; where 17.000 < vd10 < 40.000, 45.000 < vd11 < 77.000. Through a certain combination of Abbe numbers, the chromatic aberration of the third lens group S3 itself can be well optimized, which is beneficial to reducing the lateral chromatic aberration of different fields of the system and improving the overall image quality of the system.

[0080] Based on the above embodiments, the refractive index of the twelfth lens 112 is nd12, and the Abbe number of the thirteenth lens 113 is vd13; where 1.4900 < nd12 < 2.0000, 35.000 < vd13 < 75.000. Selecting lenses with certain refractive indices and Abbe numbers for the fourth lens group S4 can reduce the spherical aberration and axial chromatic aberration of the system, and finally ensure good image quality for different fields of the system.

[0081] Based on the above embodiments, the seventh lens 107 and the eighth lens 108 are adhesively disposed.

[0082] Specifically, the bonding of different lenses can be understood as the image side surface of the preceding lens and the object side surface of the following lens in the optical path being bonded together and having the same surface shape. Figure 1 As shown, the seventh lens 107 and the eighth lens 108 are glued together, which can be understood as the image-side surface of the seventh lens 107 and the object-side surface of the eighth lens 108 being in contact with each other.

[0083] Further, in Figure 1 In the illustrated solution, the first lens 101 and the second lens 102 can be cemented together, the third lens 103 and the fourth lens 104 can be cemented together, and the tenth lens 110 and the eleventh lens 111 can be cemented together. Cemented lenses can be used to minimize or eliminate chromatic aberration. Using cemented lenses in teleconverters can improve image quality and reduce reflection loss of light energy, thereby enhancing the clarity of the lens image. Furthermore, cementing the lenses eliminates the air gap between the two lenses, making the overall optical system compact and meeting the requirements of system miniaturization. Furthermore, cementing the lenses reduces tolerance sensitivity issues such as tilt and deflection that may occur during the assembly process of the lens unit.

[0084] Furthermore, the two lenses glued together can be supported by a gasket or glued together. The embodiment of the present invention does not limit the specific implementation method of gluing.

[0085] On the basis of the above embodiment, the first lens 101 includes a first object-side surface close to the object plane and a first image-side surface close to the image plane, the first object-side surface is convex, and the first image-side surface is convex; the second lens 102 includes a second object-side surface close to the object plane and a second image-side surface close to the image plane, the second object-side surface is concave, and the second image-side surface is convex; the third lens 103 includes a third object-side surface close to the object plane and a third image-side surface close to the image plane, the third object-side surface is convex, and the third image-side surface is convex; the fourth lens 104 includes The fourth object-side surface close to the object plane and the fourth image-side surface close to the image plane, the fourth object-side surface is concave, and the fourth image-side surface is concave; the fifth lens 105 includes a fifth object-side surface close to the object plane and a fifth image-side surface close to the image plane, the fifth object-side surface is concave, and the fifth image-side surface is convex; the sixth lens 106 includes a sixth object-side surface close to the object plane and a sixth image-side surface close to the image plane, the sixth object-side surface is convex, and the sixth image-side surface is concave; the seventh lens 107 includes a seventh object-side surface close to the object plane and a fifth image-side surface close to the image plane The seventh image side surface of the lens element 106 is convex, the seventh object side surface is convex, and the seventh image side surface is convex; the eighth lens element 108 includes an eighth object side surface close to the object plane and an eighth image side surface close to the image plane, the eighth object side surface is concave, and the eighth image side surface is concave; the ninth lens element 106 includes a ninth object side surface close to the object plane and a ninth image side surface close to the image plane, the ninth object side surface is concave, and the ninth image side surface is convex; the tenth lens element 110 includes a tenth object side surface close to the object plane and a tenth image side surface close to the image plane, the tenth object side surface is concave, and the tenth image side surface is The surface is concave; the eleventh lens 111 includes an eleventh object-side surface close to the object plane and an eleventh image-side surface close to the image plane, the eleventh object-side surface is convex, and the eleventh image-side surface is convex; the twelfth lens 112 includes a twelfth object-side surface close to the object plane and a twelfth image-side surface close to the image plane, the twelfth object-side surface is concave, and the twelfth image-side surface is convex; the thirteenth lens 113 includes a thirteenth object-side surface close to the object plane and a thirteenth image-side surface close to the image plane, the thirteenth object-side surface is convex, and the thirteenth image-side surface is convex.

[0086] Specifically, the object-side surface of the lens can be understood as the surface of the lens close to the object plane, and the image-side surface of the lens can be understood as the surface of the lens close to the image plane.

[0087] The object-side surface of the first lens 101 is convex, and the image-side surface is convex. It can be understood that the object-side surface of the first lens 101 is convex toward the object plane at a position near the optical axis, and the image-side surface is convex toward the image plane at a position near the optical axis, that is, the first lens 101 is a lens with a double convex structure.

[0088] The object-side surface of the second lens 102 is concave, and the image-side surface is convex. It can be understood that the object-side surface of the second lens 102 is concave toward the object plane at a position near the optical axis, and the image-side surface is convex toward the image plane at a position near the optical axis, that is, the second lens 102 is a lens with a concave-convex structure.

[0089] The object-side surface of the third lens 103 is convex, and the image-side surface is convex. It can be understood that the object-side surface of the third lens 103 is convex toward the object plane at a position near the optical axis, and the image-side surface is convex toward the image plane at a position near the optical axis, that is, the third lens 103 is a lens with a double convex structure.

[0090] The object-side surface and the image-side surface of the fourth lens 104 are concave. It can be understood that the object-side surface of the fourth lens 104 is concave toward the object plane at a position near the optical axis, and the image-side surface is concave toward the image plane at a position near the optical axis, that is, the fourth lens 104 is a lens with a double concave structure.

[0091] The object-side surface of the fifth lens element 105 is concave, and the image-side surface is convex. It can be understood that the object-side surface of the fifth lens element 105 is concave toward the object plane at a position near the optical axis, and the image-side surface is convex toward the image plane at a position near the optical axis, that is, the fifth lens element 105 is a lens with a concave-convex structure.

[0092] The object-side surface of the sixth lens 106 is convex, and the image-side surface is concave. It can be understood that the object-side surface of the sixth lens 106 is convex toward the object plane at a position near the optical axis, and the image-side surface is concave toward the image plane at a position near the optical axis, that is, the sixth lens 106 can be a lens with a convex-concave structure.

[0093] The object-side surface of the seventh lens element 107 is convex, and the image-side surface is convex. It can be understood that the object-side surface of the seventh lens element 107 is convex toward the object plane at a position near the optical axis, and the image-side surface is convex toward the image plane at a position near the optical axis, that is, the seventh lens element 107 can be a lens with a double-convex structure.

[0094] The object-side surface and the image-side surface of the eighth lens element 108 are concave. It can be understood that the object-side surface of the eighth lens element 108 is concave toward the object plane at a position near the optical axis, and the image-side surface is concave toward the image plane at a position near the optical axis, that is, the eighth lens element 108 is a lens with a double concave structure.

[0095] The object-side surface of the ninth lens element 109 is concave, and the image-side surface is convex. It can be understood that the object-side surface of the ninth lens element 109 is concave toward the object plane at a position near the optical axis, and the image-side surface is convex toward the image plane at a position near the optical axis, that is, the ninth lens element 109 can be a lens with a concave-convex structure.

[0096] The object-side surface and the image-side surface of the tenth lens 110 are concave. It can be understood that the object-side surface of the tenth lens 110 is concave toward the object plane at a position near the optical axis, and the image-side surface is concave toward the image plane at a position near the optical axis, that is, the tenth lens 110 is a lens with a double concave structure.

[0097] The object-side surface of the eleventh lens 111 is convex, and the image-side surface is convex. It can be understood that the object-side surface of the eleventh lens 111 is convex toward the object plane at a position near the optical axis, and the image-side surface is convex toward the image plane at a position near the optical axis, that is, the eleventh lens 111 can be a lens with a double-convex structure.

[0098] The object-side surface of the twelfth lens 112 is concave, and the image-side surface is convex. It can be understood that the object-side surface of the twelfth lens 112 is concave toward the object plane at a position near the optical axis, and the image-side surface is convex toward the image plane at a position near the optical axis, that is, the twelfth lens 112 is a lens with a concave-convex structure.

[0099] The object-side surface of the thirteenth lens 113 is convex, and the image-side surface is convex. It can be understood that the object-side surface of the thirteenth lens 113 is convex toward the object plane at a position near the optical axis, and the image-side surface is convex toward the image plane at a position near the optical axis, that is, the thirteenth lens 113 can be a lens with a double convex structure.

[0100] By properly setting the concave and convex surface shapes of each lens, it is possible to ensure that each lens modulates the light emission angle. In addition, for a cemented lens, at least two adjacent lenses can be cemented together. On the other hand, the distance between adjacent lenses can be reduced, which is conducive to the design of a small-volume teleconverter lens.

[0101] Based on the above embodiment, the first lens 101, the second lens 102, the third lens 103, the fourth lens 104, the fifth lens 105, the sixth lens 106, the seventh lens 107, the eighth lens 108, the ninth lens 109, the tenth lens 110, the eleventh lens 111, the twelfth lens 112 and the thirteenth lens 113 are all glass spherical lenses.

[0102] Specifically, spherical lenses are characterized by a constant curvature from the center to the periphery, ensuring simple lens configuration. Furthermore, because glass lenses have a low coefficient of thermal expansion and excellent stability, the first through thirteenth lenses 101, 113 are all glass spherical lenses. Glass spherical lenses offer greater thermal stability, ensuring good resolution over a wide temperature range when handling a wide range of optical powers. Furthermore, the wider range of glass materials available allows for relatively flexible selection of refractive index and Abbe number, allowing for a certain degree of control over higher-order aberrations and chromatic aberrations, meeting the demands of complex operating conditions.

[0103] Based on the above embodiment, the teleconverter lens further includes an aperture (not shown in the figure), which is arranged on the image side of the thirteenth lens 113. The aperture can adjust the propagation direction of the light beam, which is conducive to improving the imaging quality.

[0104] Furthermore, the teleconverter provided by the embodiment of the present invention can also be equipped with an ideal optical surface (i.e., a paraxial surface) placed behind the teleconverter to monitor the performance of the teleconverter, so that the lens can meet the following requirements: a module magnification of 2× or greater, a field of view of 12° or greater, distortion of less than 0.5%, and a total length of less than 120 mm. Furthermore, the lens MTF resolution can still reach greater than 0.3 at 100 lp / mm, ultimately achieving the characteristics of low distortion, short total length, and high image quality of the teleconverter.

[0105] As a feasible implementation method, the parameters of each lens in the teleconverter lens are described below.

[0106] Table 1 Optical design values of the teleconverter lens in Example 1

[0107] Example 1 Lower limit Upper limit <![CDATA[f1 / f2]]> 2.3483 2.1100 2.5900 <![CDATA[f z1 / f z2 ]]> 0.9196 0.8200 1.2700 <![CDATA[f z3 / f z4 ]]> 1.8662 1.6800 7.3000 <![CDATA[SAG11 / SAG25]]> -0.5224 -0.5800 -0.3500 <![CDATA[SAG1 10 / SAG2 11 , 0.0875 0.0500 0.2400 <![CDATA[SAG1 12 / SAG2 13 , 1.1158 1.0000 2.5500 <![CDATA[SAG11 / SAG16]]> 0.4565 0.3200 0.5100 <![CDATA[SAG1 10 / SAG1 12 ]]> 0.2057 0.0400 0.5700 <![CDATA[SAG2 11 / SAG2 13 , 2.6228 1.6500 3.2200 vd1 59.977 51.000 98.000 vd2 23.643 21.000 42.000 vd3 50.573 40.000 98.000 vd4 39.305 24.000 52.000 nd5 1.9482 1.6500 2.0000 nd6 1.9178 1.6600 2.0000 nd7 1.7133 1.5000 1.8700 nd8 1.9651 1.6600 2.0000 nd9 1.9497 1.4800 2.0000 vd10 23.958 17.000 40.000 vd11 61.651 45.000 77.000 nd12 1.9323 1.4900 2.0000 vd13 40.431 35.000 75.000

[0108] Table 2 Design values of optical physical parameters of teleconverter lens

[0109]

[0110] Among them, the surface numbers are numbered according to the surface order of each lens. For example, the surface number "S1" represents the object side of the first lens, the surface number "S2" represents the image side of the first lens, and so on; "STO" represents the aperture of the lens; the radius of curvature represents the degree of curvature of the lens surface, a positive value represents that the surface is bent toward the image side, with the center close to the image plane, and a negative value represents that the surface is bent toward the object side, with the center close to the object plane, where "Infinity" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the axial distance from the center of the current surface to the next surface; and because the number of digits of each parameter is different, the number of Due to the focus error, the thickness of the STO surface is not given in specific values. The value can be adjusted as needed to achieve clear focus. Also, because this system is a telephoto system, the object and image are focused at infinity. Therefore, a paraxial surface is set at the STO to test the imaging quality of the lens. The paraxial surface can be regarded as an ideal thin lens. Material (nd) represents the refractive index, that is, the ability of the material between the current surface and the next surface to deflect light. A blank space represents the current position as air with a refractive index of 1. Material (vd) represents the Abbe number, that is, the dispersion characteristics of the material between the current surface and the next surface. A blank space represents the current position as air. Semi-diameter represents the semi-aperture diameter of the lens.

[0111] According to Abbe's formula, for most so-called "normal glasses" (H-K6 and F4 are selected as "normal glasses"), the following linear relationship is established:

[0112] P x,y =m x,y *v d +b x,y

[0113] This linear relationship is based on P x,y is the vertical coordinate, v d It is represented by the horizontal axis, where m x,y is the slope, b x,y is the intercept.

[0114] As is known to all, the correction of the secondary spectrum, i.e. the achromatization of more than two wavelengths, requires at least one glass that does not conform to the above formula (i.e. its P x,y The deviation value deviates from Abbe's empirical formula), and the deviation value is expressed as dP x,y If it is expressed as, then each P x,y -v d The point is shifted by dP relative to the "normal line" that meets the above formula x,y Thus, the dP of each brand of glass x,y The value can be calculated using the following formula:

[0115] P x,y =m x,y *v d +b x,y +dP x,y

[0116] Therefore, dP x,y It quantitatively expresses the deviation characteristics of special dispersion compared with "normal glass".

[0117] dP g,F The calculation formula is as follows:

[0118] dP g,F =P g,F -0.6457+0.001703*v d .

[0119] Figure 2 This is a schematic diagram of the spherical aberration curve of a teleconverter lens provided in Example 1 of the present invention. In the figure, the vertical direction represents the normalization of the zero field of view pupil plane, 0 represents the pupil center, and the vertical vertex represents the pupil vertex; the horizontal direction represents the spherical aberration of different wavelengths, in millimeters (mm). Figure 2 It can be seen that the spherical aberration at different wavelengths (435nm, 470nm, 510nm, 555nm, 610nm and 650mm) is all controlled within the range of (-0.01mm, +0.01mm), indicating that the spherical aberration of this teleconverter at each wavelength is well controlled and can meet the needs of wide-spectrum applications.

[0120] Figure 3This is a schematic diagram of the vertical axis chromatic aberration curve of a teleconverter lens provided in Example 1 of the present invention. The vertical direction in the figure represents the field of view angle, 0 represents the field of view angle when incident parallel to the optical axis, and the vertical vertex represents the maximum half field of view angle; the horizontal direction represents the offset of the meridian range with 0.555μm as the reference, in microns (μm). The numbers on the curve in the figure represent the wavelength represented by the curve, in microns (μm). Figure 3 It can be seen that the vertical chromatic aberration of different wavelengths (435nm, 470nm, 510nm, 555nm, 610nm and 650mm) is all controlled within a good range, indicating that the vertical chromatic aberration of the optical lens is well controlled and can meet the needs of wide spectrum applications.

[0121] Figure 4 This is a schematic diagram of the distortion curve of a teleconverter lens provided in Example 1 of the present invention. The left figure in the figure is a field curvature diagram. The vertical direction represents the field angle, 0 represents the field angle when incident parallel to the optical axis, and the vertical vertex represents the maximum field angle. The horizontal direction represents the offset with 0.555μm as the reference meridian range, in millimeters (mm). Figure 4 As can be seen, the lens provided by this embodiment effectively controls field curvature, meaning that the difference in image quality between the center and the periphery is minimal. The figure on the right shows a distortion diagram, with the vertical axis representing the field of view angle, 0 representing the angle of incidence parallel to the optical axis, and the vertical vertex representing the maximum field of view angle. The horizontal distortion is expressed as a unitless percentage. As can be seen from the figure, the lens provided by this embodiment exhibits minimal distortion, within 0.5%.

[0122] Figure 5 It is a schematic diagram of the MTF curve of a teleconverter lens provided in the first embodiment of the present invention. The MTF curve represents the resolution of the optical system for objects at different frequencies in different fields of view, meridian and sagittal directions, and reflects the degree of imaging quality of the object after passing through the optical system. The most ideal curve is the highest diffraction limit, which indicates the physical limit of the lens under this parameter. The vertical coordinate of the curve corresponds to the boundary contrast of black and white lines (M' / M), where M refers to the grating modulation before imaging, and M' refers to the grating modulation after imaging, so 0≤M' / M≤1. The horizontal coordinate corresponds to the number of black and white lines within 1mm. S and T correspond to the sagittal and meridian of each field of view. By Figure 5 It can be seen that the system is close to the diffraction limit at all wavelengths in all fields of view, indicating that the aberrations of the system at all wavelengths are well corrected. At the same time, there is no obvious dispersion in the sagittal and meridional of each field of view, indicating that the system astigmatism is also well corrected, thereby ensuring that the optical system can achieve high-resolution imaging requirements.

[0123] In summary, the teleconverter provided by the embodiment of the present invention has a magnification ratio of more than 2×, a field of view of more than 12°, a distortion of less than 0.5%, and a total length of less than 120 mm, ultimately achieving the characteristics of low distortion, short total length, and high image quality.

[0124] Example 2

[0125] Figure 6 FIG. 1 is a structural diagram of a teleconverter lens provided in the second embodiment of the present invention. Figure 6 As shown, the teleconverter lens provided in the second embodiment of the present invention includes a front group G1 and a rear group G2 arranged in sequence along the optical axis from the object plane to the image plane; the front group G1 includes a first lens group S1 and a second lens group S2 arranged in sequence along the optical axis from the object plane to the image plane, and the rear group G2 includes a third lens group S3 and a fourth lens group S4 arranged in sequence along the optical axis from the object plane to the image plane; the first lens group S1 includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104 and a fifth lens 105 arranged in sequence along the optical axis from the object plane to the image plane; the second lens group S2 includes a first lens group S1 and a second lens group S2 arranged in sequence along the optical axis from the object plane to the image plane The sixth lens 106, the seventh lens 107, the eighth lens 108 and the ninth lens 109 are arranged in sequence along the optical axis from the object plane to the image plane; the third lens group S3 includes a tenth lens 110 and an eleventh lens 111 arranged in sequence along the optical axis from the object plane to the image plane; the fourth lens group S4 includes a twelfth lens 112 and a thirteenth lens 113 arranged in sequence along the optical axis from the object plane to the image plane; wherein the focal length of the first lens group S1 is fz1, the focal length of the second lens group S2 is fz2, the focal length of the third lens group S3 is fz3, and the focal length of the fourth lens group S4 is fz4; wherein, 0.8200 <fz1 / fz2<1.2700,1.6800<fz3 / fz4<7.3000。

[0126] Other parameters are the same as those in the first embodiment and will not be described again here.

[0127] As another feasible implementation, specific parameters of the teleconverter lens are described below.

[0128] Table 3 Optical design values of the teleconverter lens in Example 2

[0129] Example 2 Lower limit Upper limit <![CDATA[f1 / f2]]> 2.3494 2.1100 2.5900 <![CDATA[f z1 / f z2 ]]> 1.0953 0.8200 1.2700 <![CDATA[f z3 / f z4 ]]> 1.9979 1.6800 7.3000 <![CDATA[SAG11 / SAG25]]> -0.4983 -0.5800 -0.3500 <![CDATA[SAG1 10 / SAG2 11 , 0.2133 0.0500 0.2400 <![CDATA[SAG1 12 / SAG2 13 , 1.2178 1.0000 2.5500 <![CDATA[SAG11 / SAG16]]> 0.4274 0.3200 0.5100 <![CDATA[SAG1 10 / SAG1 12 ]]> 0.5129 0.0400 0.5700 <![CDATA[SAG2 11 / SAG2 13 , 2.9277 1.6500 3.2200 vd1 94.000 51.000 98.000 vd2 37.988 21.000 42.000 vd3 43.831 40.000 98.000 vd4 27.469 24.000 52.000 nd5 1.7769 1.6500 2.0000 nd6 1.8576 1.6600 2.0000 nd7 1.6062 1.5000 1.8700 nd8 1.8569 1.6600 2.0000 nd9 1.9621 1.4800 2.0000 vd10 34.034 17.000 40.000 vd11 54.014 45.000 77.000 nd12 1.5138 1.4900 2.0000 vd13 69.131 35.000 75.000

[0130] Table 4 Design values of optical physical parameters of teleconverter lens

[0131]

[0132] Among them, the surface numbers are numbered according to the surface order of each lens. For example, the surface number "S1" represents the object side of the first lens, the surface number "S2" represents the image side of the first lens, and so on; "STO" represents the aperture of the lens; the radius of curvature represents the degree of curvature of the lens surface, a positive value represents that the surface is bent toward the image side, with the center close to the image plane, and a negative value represents that the surface is bent toward the object side, with the center close to the object plane, where "Infinity" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the axial distance from the center of the current surface to the next surface; and because the number of digits of each parameter is different, the number of Due to the focus error, the thickness of the STO surface is not given in specific values. The value can be adjusted as needed to achieve clear focus. Also, because this system is a telephoto system, the object and image are focused at infinity. Therefore, a paraxial surface is set at the STO to test the imaging quality of the lens. The paraxial surface can be regarded as an ideal thin lens. Material (nd) represents the refractive index, that is, the ability of the material between the current surface and the next surface to deflect light. A blank space represents the current position as air with a refractive index of 1. Material (vd) represents the Abbe number, that is, the dispersion characteristics of the material between the current surface and the next surface. A blank space represents the current position as air. Semi-diameter represents the semi-aperture diameter of the lens.

[0133] According to Abbe's formula, for most so-called "normal glasses" (H-K6 and F4 are selected as "normal glasses"), the following linear relationship is established:

[0134] P x,y =m x,y *v d +b x,y

[0135] This linear relationship is based on P x,y is the vertical coordinate, v d It is represented by the horizontal axis, where m x,y is the slope, b x,y is the intercept.

[0136] As is known to all, the correction of the secondary spectrum, i.e. the achromatization of more than two wavelengths, requires at least one glass that does not conform to the above formula (i.e. its P x,y The deviation value deviates from Abbe's empirical formula), and the deviation value is expressed as dP x,y If it is expressed as, then each P x,y -v d The point is shifted by dP relative to the "normal line" that meets the above formula x,y Thus, the dP of each brand of glass x,y The value can be calculated using the following formula:

[0137] P x,y =m x,y *v d +bx,y +dP x,y

[0138] Therefore, dP x,y It quantitatively expresses the deviation characteristics of special dispersion compared with "normal glass".

[0139] dP g,F The calculation formula is as follows:

[0140] dP g,F =P g,F -0.6457+0.001703*v d .

[0141] Figure 7 This is a schematic diagram of the spherical aberration curve of a teleconverter lens provided by the second embodiment of the present invention. In the figure, the vertical direction represents the normalization of the zero field of view pupil plane, 0 represents the pupil center, and the vertical vertex represents the pupil vertex; the horizontal direction represents the spherical aberration of different wavelengths, in millimeters (mm). Figure 7 It can be seen that the spherical aberration at different wavelengths (435nm, 470nm, 510nm, 555nm, 610nm and 650mm) is all controlled within the range of (-0.01mm, +0.01mm), indicating that the spherical aberration of this teleconverter at each wavelength is well controlled and can meet the needs of wide-spectrum applications.

[0142] Figure 8 This is a schematic diagram of the vertical axis chromatic aberration curve of a teleconverter lens provided in Example 2 of the present invention. The vertical direction in the figure represents the field of view angle, 0 represents the field of view angle when incident parallel to the optical axis, and the vertical vertex represents the maximum half field of view angle; the horizontal direction represents the offset from the reference meridian range of 0.555μm, in micrometers (μm). The numbers on the curve in the figure represent the wavelength represented by the curve, in micrometers (μm). Figure 8 It can be seen that the vertical chromatic aberration of different wavelengths (435nm, 470nm, 510nm, 555nm, 610nm and 650mm) is all controlled within a good range, indicating that the vertical chromatic aberration of the optical lens is well controlled and can meet the needs of wide spectrum applications.

[0143] Figure 9 This is a schematic diagram of the distortion curve of a teleconverter lens provided in Example 2 of the present invention. The left figure in the figure is a field curvature diagram. The vertical direction represents the field angle, 0 represents the field angle when incident parallel to the optical axis, and the vertical vertex represents the maximum field angle. The horizontal direction represents the offset with 0.555μm as the reference meridian range, in millimeters (mm). Figure 9As can be seen, the lens provided by this embodiment effectively controls field curvature, meaning that the difference in image quality between the center and the periphery is minimal. The figure on the right shows a distortion diagram, with the vertical axis representing the field of view angle, 0 representing the angle of incidence parallel to the optical axis, and the vertical vertex representing the maximum field of view angle. The horizontal distortion is expressed as a unitless percentage. As can be seen from the figure, the lens provided by this embodiment exhibits minimal distortion, within 0.5%.

[0144] Figure 10 It is a schematic diagram of the MTF curve of a teleconverter lens provided in the second embodiment of the present invention. The MTF curve shows the resolution of the optical system for objects at different frequencies in different fields of view, meridian and sagittal directions, and reflects the degree of imaging quality of the object after passing through the optical system. The most ideal curve is the highest diffraction limit, which shows the physical limit of the lens under this parameter. The vertical coordinate of the curve corresponds to the boundary contrast of black and white lines (M' / M), where M refers to the grating modulation before imaging, and M' refers to the grating modulation after imaging, so 0≤M' / M≤1. The horizontal coordinate corresponds to the number of black and white lines within 1mm. S and T correspond to the sagittal and meridian of each field of view. By Figure 10 It can be seen that the system is close to the diffraction limit at all wavelengths in all fields of view, indicating that the aberrations of the system at all wavelengths are well corrected. At the same time, there is no obvious dispersion in the sagittal and meridional of each field of view, indicating that the system astigmatism is also well corrected, thereby ensuring that the optical system can achieve high-resolution imaging requirements.

[0145] In summary, the teleconverter provided by the embodiment of the present invention has a magnification ratio of more than 2×, a field of view of more than 12°, a distortion of less than 0.5%, and a total length of less than 120 mm, ultimately achieving the characteristics of low distortion, short total length, and high image quality.

[0146] Example 3

[0147] Figure 11 FIG. 1 is a structural diagram of a teleconverter lens provided in the third embodiment of the present invention. Figure 11As shown, the teleconverter lens provided in the third embodiment of the present invention includes a front group G1 and a rear group G2 arranged in sequence along the optical axis from the object plane to the image plane; the front group G1 includes a first lens group S1 and a second lens group S2 arranged in sequence along the optical axis from the object plane to the image plane, and the rear group G2 includes a third lens group S3 and a fourth lens group S4 arranged in sequence along the optical axis from the object plane to the image plane; the first lens group S1 includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104 and a fifth lens 105 arranged in sequence along the optical axis from the object plane to the image plane; the second lens group S2 includes a first lens group S1 and a second lens group S2 arranged in sequence along the optical axis from the object plane to the image plane The sixth lens 106, the seventh lens 107, the eighth lens 108 and the ninth lens 109 are arranged in sequence along the optical axis from the object plane to the image plane; the third lens group S3 includes a tenth lens 110 and an eleventh lens 111 arranged in sequence along the optical axis from the object plane to the image plane; the fourth lens group S4 includes a twelfth lens 112 and a thirteenth lens 113 arranged in sequence along the optical axis from the object plane to the image plane; wherein the focal length of the first lens group S1 is fz1, the focal length of the second lens group S2 is fz2, the focal length of the third lens group S3 is fz3, and the focal length of the fourth lens group S4 is fz4; wherein, 0.8200 <fz1 / fz2<1.2700,1.6800<fz3 / fz4<7.3000。

[0148] The difference between the third embodiment and the first embodiment is that the first lens 101 and the second lens 102 are not cemented, the third lens 103 and the fourth lens 104 are not cemented, and the tenth lens 110 and the eleventh lens 111 are not cemented.

[0149] The rest is the same as that of the first embodiment and will not be described again here.

[0150] As another feasible implementation, specific parameters of the teleconverter lens are described below.

[0151] Table 5 Optical design values of the teleconverter lens in Example 3

[0152] Example 3 Lower limit Upper limit <![CDATA[f1 / f2]]> 2.3476 2.1100 2.5900 <![CDATA[f z1 / f z2 ]]> 1.1511 0.8200 1.2700 <![CDATA[f z3 / f z4 ]]> 6.6303 1.6800 7.3000 <![CDATA[SAG11 / SAG25]]> -0.3982 -0.5800 -0.3500 <![CDATA[SAG1 10 / SAG2 11 , 0.0570 0.0500 0.2400 <![CDATA[SAG1 12 / SAG2 13 , 2.3117 1.0000 2.5500 <![CDATA[SAG11 / SAG16]]> 0.3614 0.3200 0.5100 <![CDATA[SAG1 10 / SAG1 12 ]]> 0.0452 0.0400 0.5700 <![CDATA[SAG2 11 / SAG2 13 , 1.8337 1.6500 3.2200 vd1 56.674 51.000 98.000 vd2 25.728 21.000 42.000 vd3 90.000 40.000 98.000 vd4 46.939 24.000 52.000 nd5 1.8966 1.6500 2.0000 nd6 1.9089 1.6600 2.0000 nd7 1.6882 1.5000 1.8700 nd8 1.9415 1.6600 2.0000 nd9 1.5039 1.4800 2.0000 vd10 18.000 17.000 40.000 vd11 68.919 45.000 77.000 nd12 1.9510 1.4900 2.0000 vd13 46.240 35.000 75.000

[0153] Table 6 Design values of optical physical parameters of teleconverter lens

[0154]

[0155] Among them, the surface numbers are numbered according to the surface order of each lens. For example, the surface number "S1" represents the object side of the first lens, the surface number "S2" represents the image side of the first lens, and so on; "STO" represents the aperture of the lens; the radius of curvature represents the degree of curvature of the lens surface, a positive value represents that the surface is bent toward the image side, with the center close to the image plane, and a negative value represents that the surface is bent toward the object side, with the center close to the object plane, where "Infinity" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the axial distance from the center of the current surface to the next surface; and because the number of digits of each parameter is different, the number of Due to the focus error, the thickness of the STO surface is not given in specific values. The value can be adjusted as needed to achieve clear focus. Also, because this system is a telephoto system, the object and image are focused at infinity. Therefore, a paraxial surface is set at the STO to test the imaging quality of the lens. The paraxial surface can be regarded as an ideal thin lens. Material (nd) represents the refractive index, that is, the ability of the material between the current surface and the next surface to deflect light. A blank space represents the current position as air with a refractive index of 1. Material (vd) represents the Abbe number, that is, the dispersion characteristics of the material between the current surface and the next surface. A blank space represents the current position as air. Semi-diameter represents the semi-aperture diameter of the lens.

[0156] According to Abbe's formula, for most so-called "normal glasses" (H-K6 and F4 are selected as "normal glasses"), the following linear relationship is established:

[0157] P x,y =m x,y *v d +b x,y

[0158] This linear relationship is based on P x,y is the vertical coordinate, v d It is represented by the horizontal axis, where m x,y is the slope, b x,y is the intercept.

[0159] As is known to all, the correction of the secondary spectrum, i.e. the achromatization of more than two wavelengths, requires at least one glass that does not conform to the above formula (i.e. its P x,y The deviation value deviates from Abbe's empirical formula), and the deviation value is expressed as dP x,y If it is expressed as, then each P x,y -v d The point is shifted by dP relative to the "normal line" that meets the above formula x,y Thus, the dP of each brand of glass x,y The value can be calculated using the following formula:

[0160] P x,y =m x,y *v d +bx,y +dP x,y

[0161] Therefore, dP x,y It quantitatively expresses the deviation characteristics of special dispersion compared with "normal glass".

[0162] dP g,F The calculation formula is as follows:

[0163] dP g,F =P g,F -0.6457+0.001703*v d .

[0164] Figure 12 This is a schematic diagram of the spherical aberration curve of a teleconverter lens provided in Example 3 of the present invention. In the figure, the vertical direction represents the normalization of the zero field of view pupil plane, 0 represents the pupil center, and the vertical vertex represents the pupil vertex; the horizontal direction represents the spherical aberration of different wavelengths, in millimeters (mm). Figure 12 It can be seen that the spherical aberration at different wavelengths (435nm, 470nm, 510nm, 555nm, 610nm and 650mm) is all controlled within the range of (-0.01mm, +0.01mm), indicating that the spherical aberration of this teleconverter at each wavelength is well controlled and can meet the needs of wide-spectrum applications.

[0165] Figure 13 This is a schematic diagram of the vertical axis chromatic aberration curve of a teleconverter lens provided in Example 3 of the present invention. The vertical direction in the figure represents the field of view angle, 0 represents the field of view angle when incident parallel to the optical axis, and the vertical vertex represents the maximum half field of view angle; the horizontal direction represents the offset of the meridian range with 0.555μm as the reference, in microns (μm). The numbers on the curve in the figure represent the wavelength represented by the curve, in microns (μm). Figure 13 It can be seen that the vertical chromatic aberration of different wavelengths (435nm, 470nm, 510nm, 555nm, 610nm and 650mm) is all controlled within a good range, indicating that the vertical chromatic aberration of the optical lens is well controlled and can meet the needs of wide spectrum applications.

[0166] Figure 14 This is a schematic diagram of the distortion curve of a teleconverter lens provided in Example 3 of the present invention. The left figure in the figure is a field curvature diagram. The vertical direction represents the field angle, 0 represents the field angle when the incident light is parallel to the optical axis, and the vertical vertex represents the maximum field angle. The horizontal direction represents the offset with 0.555μm as the reference meridian range, in millimeters (mm). Figure 14As can be seen, the lens provided by this embodiment effectively controls field curvature, meaning that the difference in image quality between the center and the periphery is minimal. The figure on the right shows a distortion diagram, with the vertical axis representing the field of view angle, 0 representing the angle of incidence parallel to the optical axis, and the vertical vertex representing the maximum field of view angle. The horizontal distortion is expressed as a unitless percentage. As can be seen from the figure, the lens provided by this embodiment exhibits minimal distortion, within 0.5%.

[0167] Figure 15 It is a schematic diagram of the MTF curve of a teleconverter lens provided in Example 3 of the present invention. The MTF curve represents the resolution of the optical system for objects at different frequencies in different fields of view, meridian and sagittal directions, and reflects the degree of imaging quality of the object after passing through the optical system. The most ideal curve is the highest diffraction limit, which indicates the physical limit of the lens under this parameter. The vertical coordinate of the curve corresponds to the boundary contrast of black and white lines (M' / M), where M refers to the grating modulation before imaging, and M' refers to the grating modulation after imaging, so 0≤M' / M≤1. The horizontal coordinate corresponds to the number of black and white lines within 1mm. S and T correspond to the sagittal and meridian of each field of view. By Figure 10 It can be seen that the system is close to the diffraction limit at all wavelengths in all fields of view, indicating that the aberrations of the system at all wavelengths are well corrected. At the same time, there is no obvious dispersion in the sagittal and meridional of each field of view, indicating that the system astigmatism is also well corrected, thereby ensuring that the optical system can achieve high-resolution imaging requirements.

[0168] In summary, the teleconverter provided by the embodiment of the present invention has a magnification ratio of more than 2×, a field of view of more than 12°, a distortion of less than 0.5%, and a total length of less than 120 mm, ultimately achieving the characteristics of low distortion, short total length, and high image quality.

[0169] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A teleconverter lens, characterized in that: It includes a system front group and a system rear group arranged in sequence from the object plane to the image plane along the optical axis; The front lens group includes a first lens group and a second lens group arranged in sequence from the object plane to the image plane along the optical axis, and the rear lens group includes a third lens group and a fourth lens group arranged in sequence from the object plane to the image plane along the optical axis; The first lens group includes a first lens, a second lens, a third lens, a fourth lens and a fifth lens arranged in sequence from the object plane to the image plane along the optical axis; The second lens group includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged in sequence from the object plane to the image plane along the optical axis; The third lens group includes a tenth lens and an eleventh lens arranged in sequence from the object plane to the image plane along the optical axis; The fourth lens group includes a twelfth lens and a thirteenth lens arranged in sequence from the object plane to the image plane along the optical axis; Wherein, the focal length of the first lens group is f z1 , the focal length of the second lens group is f z2 , the focal length of the third lens group is f z3 , the focal length of the fourth lens group is f z4 ; Among them, 0.8200 <f z1 / f z2 <1.2700, 1.6800 <f z3 / f z4 <7.3000.

2. The teleconverter lens according to claim 1, wherein: The combined focal length of the front group of the system is f1, and the combined focal length of the rear group of the system is f2; Among them, 2.1100 <f1 / f2<2.5900。 3. The teleconverter lens according to claim 1, wherein: The first lens is a positive power lens, the second lens is a negative power lens, the third lens is a positive power lens, the fourth lens is a negative power lens, the fifth lens is a positive power lens, the sixth lens is a positive power lens, the seventh lens is a positive power lens, the eighth lens is a negative power lens, the ninth lens has power, the tenth lens is a negative power lens, the eleventh lens is a positive power lens, the twelfth lens is a positive power lens, and the thirteenth lens is a positive power lens.

4. The teleconverter lens according to claim 1, wherein: The object side sag height of the first lens is SAG11, the image side sag height of the fifth lens is SAG25, and the object side sag height of the tenth lens is SAG1 10 The image side sagittal height of the eleventh lens is SAG2 11 The object side sag height of the twelfth lens is SAG1 12 The image side sagittal height of the thirteenth lens is SAG2 13 ; Among them, -0.5800 <SAG11 / SAG25<-0.3500,0.0500<SAG1 10 / SAG2 11 <0.2400, 1.0000 <SAG1 12 / SAG2 13 <2.5500.

5. The teleconverter lens according to claim 1, wherein: The object side sag height of the first lens is SAG11, the object side sag height of the sixth lens is SAG16, and the object side sag height of the tenth lens is SAG1 10 The image side sagittal height of the eleventh lens is SAG2 11 The object side sag height of the twelfth lens is SAG1 12 The image side sagittal height of the thirteenth lens is SAG2 13 ; Among them, 0.3200 <SAG11 / SAG16<0.5100,0.0400<SAG1 10 / SAG1 12 <0.5700, 1.6500 <SAG2 11 / SAG2 13 <3.2200.

6. The teleconverter lens according to claim 1, wherein: The Abbe number of the first lens is vd1, the Abbe number of the second lens is vd2, the Abbe number of the third lens is vd3, and the Abbe number of the fourth lens is vd4; the refractive index of the fifth lens is nd5; Of these, 51,000 <vd1<98.000,1.000<vd2<42.000,40.000<vd3<98.000,24.000<vd4<52.000,1.6500<nd5<2.0000。 7. The teleconverter lens according to claim 1, wherein: The refractive index of the sixth lens is nd6, the refractive index of the seventh lens is nd7, the refractive index of the eighth lens is nd8, and the refractive index of the ninth lens is nd9; Among them, 1.6600 <nd6<2.0000,1.5000<nd7<1.8700,1.6600<nd8<2.000,1.4800<nd9<2.000。 8. The teleconverter lens according to claim 1, wherein: The Abbe number of the tenth lens is vd10, and the Abbe number of the eleventh lens is vd11; Of these, 17,000 <vd10<40.000,45.000<vd11<77.000。 9. The teleconverter lens according to claim 1, wherein: The refractive index of the twelfth lens is nd12, and the Abbe number of the thirteenth lens is vd13; Among them, 1.4900 <nd12<2.0000,35.000<vd13<75.000。 10. The teleconverter lens according to claim 1, wherein: The seventh lens and the eighth lens are cemented together.

11. The teleconverter lens according to claim 1, wherein: The first lens includes a first object-side surface close to the object plane and a first image-side surface close to the image plane, the first object-side surface is a convex surface, and the first image-side surface is a convex surface; The second lens includes a second object-side surface close to the object plane and a second image-side surface close to the image plane, the second object-side surface is concave, and the second image-side surface is convex; The third lens comprises a third object-side surface close to the object plane and a third image-side surface close to the image plane, the third object-side surface is a convex surface, and the third image-side surface is a convex surface; The fourth lens comprises a fourth object-side surface close to the object plane and a fourth image-side surface close to the image plane, the fourth object-side surface is concave, and the fourth image-side surface is concave; The fifth lens comprises a fifth object-side surface close to the object plane and a fifth image-side surface close to the image plane, the fifth object-side surface is concave, and the fifth image-side surface is convex; The sixth lens comprises a sixth object-side surface close to the object plane and a sixth image-side surface close to the image plane, the sixth object-side surface is convex, and the sixth image-side surface is concave; The seventh lens element includes a seventh object-side surface close to the object plane and a seventh image-side surface close to the image plane, the seventh object-side surface is a convex surface, and the seventh image-side surface is a convex surface; The eighth lens comprises an eighth object-side surface close to the object plane and an eighth image-side surface close to the image plane, the eighth object-side surface is concave, and the eighth image-side surface is concave; The ninth lens comprises a ninth object-side surface close to the object plane and a ninth image-side surface close to the image plane, wherein the ninth object-side surface is concave and the ninth image-side surface is convex. The tenth lens comprises a tenth object-side surface close to the object plane and a tenth image-side surface close to the image plane, the tenth object-side surface is concave, and the tenth image-side surface is concave; The eleventh lens includes an eleventh object-side surface close to the object plane and an eleventh image-side surface close to the image plane, the eleventh object-side surface is a convex surface, and the eleventh image-side surface is a convex surface; The twelfth lens comprises a twelfth object-side surface close to the object plane and a twelfth image-side surface close to the image plane, the twelfth object-side surface is concave, and the twelfth image-side surface is convex; The thirteenth lens includes a thirteenth object-side surface close to the object plane and a thirteenth image-side surface close to the image plane. The thirteenth object-side surface is a convex surface, and the thirteenth image-side surface is a convex surface.

12. The teleconverter lens according to claim 1, wherein: The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, the twelfth lens and the thirteenth lens are all glass spherical lenses.

13. The teleconverter lens according to claim 1, wherein: The teleconverter lens further includes a stop, which is disposed on the image side surface of the thirteenth lens.

Images