A zoom lens

Abstract

The application discloses a zoom lens, which comprises a first lens group, a first reflecting element, a second lens group, a second reflecting element, a third lens group and a diaphragm; the first lens group comprises a first lens with positive refractive power, a second lens with negative refractive power, a third lens with positive refractive power, a fourth lens with negative refractive power and a fifth lens with positive refractive power; the second lens group comprises a sixth lens with positive refractive power, a seventh lens with positive refractive power, an eighth lens with negative refractive power, a ninth lens with negative refractive power, a tenth lens with positive refractive power, an eleventh lens with negative refractive power and a twelfth lens with positive refractive power; the third lens group comprises a thirteenth lens with positive refractive power and a fourteenth lens with positive refractive power; the first reflecting element comprises a first right-angle prism located between the fifth lens and the sixth lens, and the second reflecting element comprises a second right-angle prism located between the twelfth lens and the thirteenth lens. The zoom lens has the advantages of high zooming, high portability and high image quality.

Description

Technical Field

[0001] This invention relates to the field of optical device technology, and in particular to a teleconverter lens. Background Technology

[0002] In recent years, high-quality photography and high-magnification zoom have become added features of new-era smartphones. Traditional mobile phone camera modules mostly adopt a single-axis structure, which is limited by the thickness of the body and the internal stacking space, making it difficult to further break through the physical focal length of telephoto lenses.

[0003] To overcome the hardware limitations of the device itself, external camera lens accessories have emerged, connecting to the phone via clips or magnets to extend macro, wide-angle, or telephoto capabilities. Currently, most external telephoto solutions on the market directly attach the add-on lens group to the phone's main camera, resulting in relatively simple optical designs. However, they generally suffer from poor field-of-view matching, insufficient aberration correction capabilities, and significant deterioration in edge image quality. Furthermore, due to the longer lens structure required to increase zoom magnification, the connection and coordinated control between the external lens and the phone's native lens are difficult, leading to a significant gap in overall imaging experience compared to built-in modules.

[0004] The emergence of periscope lens technology has provided a new approach to solving this technical challenge. By cleverly setting up prisms or mirrors to refract light, the light is allowed to propagate laterally within the phone, effectively increasing the lens's equivalent focal length without increasing the overall vertical thickness, thus achieving telephoto shooting effects. Applying periscope optical structures to external lenses allows for longer focal lengths and higher optical zoom ratios within a limited volume, while also maintaining portability, compatibility, and professional-grade imaging performance.

[0005] Therefore, it is necessary to design an optical structure and develop a periscope teleconverter lens that is portable and controllable in size and weight, can achieve high-magnification optical zoom, and at the same time ensure image quality, in order to meet the higher demands of smartphone photography at the telephoto end. Summary of the Invention

[0006] This invention provides a teleconverter lens that achieves a portable high-magnification teleconverter lens by rationally allocating the optical power of the lens and the position of the right-angle prism.

[0007] The present invention provides a teleconverter lens, comprising a first lens group, a first reflecting element, a second lens group, a second reflecting element, a third lens group, and an aperture stop arranged sequentially along the optical axis from the object plane to the image plane; the teleconverter lens has fourteen lenses with optical power.

[0008] The first lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially along the optical axis from the object plane to the image plane;

[0009] The second lens group includes a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, and a twelfth lens arranged sequentially along the optical axis from the object plane to the image plane;

[0010] The third lens group includes a thirteenth lens and a fourteenth lens arranged sequentially along the optical axis from the object plane to the image plane;

[0011] The first reflective element includes a first right-angle prism, which is located between the fifth lens and the sixth lens;

[0012] The second reflective element includes a second right-angle prism, which is located between the twelfth lens and the thirteenth lens;

[0013] The first lens has positive optical power, the second lens has negative optical power, the third lens has positive optical power, the fourth lens has negative optical power, the fifth lens has positive optical power, the sixth lens has positive optical power, the seventh lens has positive optical power, the eighth lens has negative optical power, the ninth lens has negative optical power, the tenth lens has positive optical power, the eleventh lens has negative optical power, the twelfth lens has positive optical power, the thirteenth lens has positive optical power, and the fourteenth lens has positive optical power.

[0014] Optionally, the first lens and the second lens are cemented together to form a first cemented doublet lens group; the third lens and the fourth lens are cemented together to form a second cemented doublet lens group; the seventh lens and the eighth lens are cemented together to form a third cemented doublet lens group; and the eleventh lens and the twelfth lens are cemented together to form a fourth cemented doublet lens group.

[0015] Optionally, the focal length of the teleconverter is f, the focal length of the first lens group is fA, the focal length of the second lens group is fB, and the focal length of the third lens group is fC.

[0016] Where -2.9 < fA / f + fB / f + fC / f < -2.6.

[0017] Optionally, an intermediate image plane is formed between the tenth lens and the eleventh lens; the length from the midpoint of the object side surface of the first lens to the center of the intermediate image plane is THA, and the length from the center of the intermediate image plane to the center of the aperture is THB.

[0018] Among them, 1.1 < THA / THB < 1.3.

[0019] Optionally, the optical power of the second lens group is B; The sixth lens, the seventh lens, the eighth lens, the ninth lens, and the tenth lens constitute a first sub-lens group, and the optical power of the first sub-lens group is... 6~10; The eleventh lens and the twelfth lens are cemented together to form a fourth cemented doublet lens group, and the optical power of the fourth cemented doublet lens group is... 11~12;

[0020] Among them, 1.3 < 6~10 / B+ 11~12 / B < 1.5.

[0021] Optionally, the optical power of the third lens group is C, the optical power of the thirteenth lens is 13, the optical power of the fourteenth lens is 14;

[0022] Among them, 0.9 < 13 / C+ 14 / C < 1.2.

[0023] Optionally, the optical power of the first cemented doublet lens group is 1~2; ​​the optical power of the first lens is 1. The optical power of the second lens is 2. The Abbe number of the first lens is vd1, and the Abbe number of the second lens is vd2; the optical power of the second cemented doublet lens group is... 3~4; the optical power of the third lens is 3. The optical power of the fourth lens is 4. The Abbe number of the third lens is vd3, and the Abbe number of the fourth lens is vd4; the optical power of the fourth cemented doublet lens group is... 11~12; The optical power of the eleventh lens is 11. The optical power of the twelfth lens is 12, the Abbe number of the eleventh lens is vd11, and the Abbe number of the twelfth lens is vd12;

[0024] Among them, 1000×| 1+ 2- 1~2|<0.55, 1000×|( 1 / vd1+ 2 / vd2)|<0.65;100×| 3+ 4- 3~4|<0.25, 1000×|( 3 / vd3+ 4 / vd4)|<0.6;100×| 11+ 12- 11~12|<0.3, 1000×|( 11 / vd11+ 12 / vd12)|<0.9.

[0025] Optionally, the refractive index of the fifth lens is nd5, and the refractive index of the sixth lens is nd6;

[0026] Among them, 3.7 <nd5+nd6<3.95。

[0027] Optionally, the Abbe number of the seventh lens is vd7, the Abbe number of the twelfth lens is vd12, and the focal length of the second lens group is fB; the seventh lens and the eighth lens are cemented together to form a third cemented doublet lens group, and the focal length of the third cemented doublet lens group is f7~8; the eleventh lens and the twelfth lens are cemented together to form a fourth cemented doublet lens group, and the focal length of the fourth cemented doublet lens group is f11~12;

[0028] Among them, 100 < vd7 + vd12 < 120; 0.5 < f7~8 / fB + f11~12 / fB < 1.

[0029] Optionally, the maximum half-aperture of the lens in the teleconverter is SDM, the maximum half-image height of the teleconverter is H, the distance from the midpoint of the object side surface of the first lens to the midpoint of the image side surface of the fourteenth lens is TTL, and the focal length of the teleconverter is f.

[0030] Among them, 1.5 < SDM / H < 1.7; -2.4 < TTL / f < -2.2.

[0031] The technical solution of this invention provides a teleconverter lens, including a first lens group, a first reflecting element, a second lens group, a second reflecting element, a third lens group, and an aperture stop. Specifically, it adopts a configuration of 14 lenses and 2 right-angle prisms, rationally allocating the optical power of each lens and the placement of the right-angle prisms to achieve a total teleconverter lens length of 112mm, a magnification of approximately 2.35x, |optical distortion| < 2%, image square F# = 3.14, and a maximum full-image height of 11.44mm. Its size and weight are portable and controllable, and it can achieve high-magnification optical zoom while ensuring image quality, thus meeting higher usage requirements.

[0032] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of a teleconverter lens provided in an embodiment of the present invention;

[0035] Figure 2 This is a full-frequency MTF diagram of a teleconverter lens in the visible light band provided in Embodiment 1 of the present invention;

[0036] Figure 3 This is a chromatic aberration curve of a teleconverter lens provided in Embodiment 1 of the present invention;

[0037] Figure 4 Field curvature and distortion diagram of a teleconverter lens provided in Embodiment 1 of the present invention;

[0038] Figure 5 This is a schematic diagram of the structure of a teleconverter lens provided in Embodiment 2 of the present invention;

[0039] Figure 6 This is a full-frequency MTF diagram of a teleconverter lens in the visible light band provided in Embodiment 2 of the present invention;

[0040] Figure 7 This is a chromatic aberration curve of a teleconverter lens provided in Embodiment 2 of the present invention;

[0041] Figure 8 This is a field curvature and distortion diagram of a teleconverter lens provided in Embodiment 2 of the present invention;

[0042] Figure 9 This is a schematic diagram of the structure of a teleconverter lens provided in Embodiment 3 of the present invention;

[0043] Figure 10 This is a full-frequency MTF diagram of a teleconverter lens in the visible light band provided in Embodiment 3 of the present invention;

[0044] Figure 11 This is a chromatic aberration curve of a teleconverter lens provided in Embodiment 3 of the present invention;

[0045] Figure 12This is a field curvature and distortion diagram of a teleconverter lens provided in Embodiment 3 of the present invention. Detailed Implementation

[0046] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0047] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0048] Figure 1 This is a schematic diagram of the structure of a teleconverter lens provided in an embodiment of the present invention, as shown below. Figure 1As shown, the teleconverter lens includes a first lens group 10, a first reflecting element, a second lens group 12, a second reflecting element, a third lens group 14, and an aperture stop STO arranged sequentially along the optical axis from the object plane to the image plane; the teleconverter lens has fourteen lenses with optical power; the first lens group 10 includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, and a fifth lens 105 arranged sequentially along the optical axis from the object plane to the image plane; the second lens group 12 includes a sixth lens 106, a seventh lens 107, an eighth lens 108, a ninth lens 109, a tenth lens 110, an eleventh lens 111, and a twelfth lens 112 arranged sequentially along the optical axis from the object plane to the image plane; the third lens group 14 includes a thirteenth lens 113 and a fourteenth lens 114 arranged sequentially along the optical axis from the object plane to the image plane; the first reflecting element includes a first right-angle prism. 1101, the first right-angle prism 1101 is located between the fifth lens 105 and the sixth lens 106; the second reflecting element includes a second right-angle prism 1301, which is located between the twelfth lens 112 and the thirteenth lens 113; the first lens 101 has positive optical power, the second lens 102 has negative optical power, the third lens 103 has positive optical power, the fourth lens 104 has negative optical power, the fifth lens 105 has positive optical power, the sixth lens 106 has positive optical power, the seventh lens 107 has positive optical power, the eighth lens 108 has negative optical power, the ninth lens 109 has negative optical power, the tenth lens 110 has positive optical power, the eleventh lens 111 has negative optical power, the twelfth lens 112 has positive optical power, the thirteenth lens 113 has positive optical power, and the fourteenth lens 114 has positive optical power.

[0049] In optical lenses, optical power equals the difference between the image-side beam convergence and the object-side beam convergence, characterizing the optical system's ability to deflect light. A larger absolute value of optical power indicates a stronger ability to bend light, while a smaller absolute value indicates a weaker ability. When optical power is positive, the refraction of light is converging; when optical power is negative, the refraction is diverging. Optical power can be used to characterize a single refractive surface of a lens (i.e., one surface of the lens), a single lens, or a system formed by multiple lenses (i.e., a lens group). The teleconverter provided in this embodiment is mainly used for the zoom function of electronic devices such as mobile phones. This teleconverter can house all lenses within a single lens barrel (…). Figure 1 (not shown in the image) such as Figure 1As shown, the teleconverter lens provided in this embodiment of the invention achieves a compact structure with a total length of 112mm and a magnification of approximately 2.35x through the reasonable distribution of optical power among 14 lenses. Specifically, the first lens group 10 includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, and a fifth lens 105, arranged in a positive-negative-positive-negative-positive optical power configuration to complete the pre-focusing of the incident light and primary aberration correction. The continuous positive power lenses provide the main magnification capability and can also balance field curvature and astigmatism. The first reflecting element may include a first right-angle prism 1101. The image-side surface of the fifth lens 105 and the object-side surface of the sixth lens 106 correspond to two 45-degree planes of the first right-angle prism 1101, respectively. The first right-angle prism 1101 can adjust the optical path of the light output from the fifth lens 105, which is beneficial for improving the size of the lens, facilitating miniaturization, and achieving portability of the teleconverter lens. The second lens group 12 includes a sixth lens 106, a seventh lens 107, an eighth lens 108, a ninth lens 109, a tenth lens 110, an eleventh lens 111, and a twelfth lens 112, arranged in a positive-positive-negative-negative-positive-negative-positive optical power configuration to further correct residual chromatic aberration and coma. The second reflecting element may include a second right-angle prism 1301. The image-side surface of the twelfth lens 112 and the object-side surface of the thirteenth lens 113 correspond to two 45-degree planes of the second right-angle prism 1301, respectively. The second right-angle prism 1301 can adjust the optical path of the light output from the twelfth lens 112, thereby further adjusting the size of the extender lens and facilitating its miniaturization. The third lens group 14 includes a thirteenth lens 113 and a fourteenth lens 114, arranged in a positive-positive optical power configuration. The overall optical power distribution balances high magnification and miniaturization. While achieving a magnification of 2.35x, the overall length is strictly controlled. Through the coordinated correction of aberrations by multiple lens groups, optical distortion is controlled within |2%|. The maximum compatible full image height is 11.44mm, ensuring the uniformity of on-axis and off-axis imaging. This achieves a balance between high magnification, high image quality, and portability.

[0050] Meanwhile, 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, the thirteenth lens 113, and the fourteenth lens 114 are all glass spherical lenses. The characteristic of spherical lenses is that they have a constant curvature from the center of the lens to the periphery of the lens, which ensures that the lens setting method is simple. Furthermore, due to the low coefficient of thermal expansion and good stability of glass lenses, the first lens 101, second lens 102, third lens 103, fourth lens 104, fifth lens 105, sixth lens 106, seventh lens 107, eighth lens 108, ninth lens 109, tenth lens 110, eleventh lens 111, twelfth lens 112, thirteenth lens 113, and fourteenth lens 114 can all be glass spherical lenses. The thermal properties of glass spherical lenses are more stable, ensuring good resolving power over a wide temperature range when handling higher optical power. In addition, compared to plastic aspherical lenses, glass offers a wider range of material choices, with more freedom in selecting refractive index and Abbe number. This allows for better control over higher aberrations and chromatic aberration, effectively suppressing image quality degradation caused by chromatic aberration and environmental stress, thus ensuring the lens's imaging accuracy. Moreover, the 14 glass spherical lenses are maturely manufactured with controllable precision, ensuring consistency in mass production while simultaneously handling the main optical power and basic aberration correction functions. This combination achieves the optimal performance solution for professional-grade teleconverters while ensuring a high magnification of 2.35x and a portable overall length of 112mm.

[0051] Optionally, the first lens 101 and the second lens 102 are cemented together to form a first cemented doublet lens group; the third lens 103 and the fourth lens 104 are cemented together to form a second cemented doublet lens group; the seventh lens 107 and the eighth lens 108 are cemented together to form a third cemented doublet lens group; and the eleventh lens 111 and the twelfth lens 112 are cemented together to form a fourth cemented doublet lens group.

[0052] The teleconverter lens incorporates four cemented lenses, effectively reducing the air gaps between the first lens 101 and the second lens 102, the third lens 103 and the fourth lens 104, the seventh lens 107 and the eighth lens 108, and the eleventh lens 111 and the twelfth lens 112, thereby reducing the overall lens length. Furthermore, the cemented lenses minimize or eliminate chromatic aberration, allowing for thorough correction of various aberrations in the teleconverter. This results in improved resolution and optimized optical performance, such as distortion and CRA, while maintaining a compact structure, achieving stable optical distortion control within 2%. It also reduces light loss due to inter-lens reflections, increasing illumination and thus improving image quality and sharpness. Additionally, the use of cemented lenses reduces the number of assembly components between the two lenses, simplifying the assembly process during lens manufacturing, reducing costs, and mitigating tolerance sensitivity issues such as tilt / eccentricity that occur during lens assembly.

[0053] Optionally, the focal length of the teleconverter is f, the focal length of the first lens group 10 is fA, the focal length of the second lens group 12 is fB, and the focal length of the third lens group 14 is fC; where -2.9 < fA / f + fB / f + fC / f < -2.6.

[0054] In this system, by coordinating the focal lengths of the first lens group 10, the second lens group 12, and the third lens group 14 at the system level, the sum of the ratios is negative, indicating that the first lens group 10, the second lens group 12, and the third lens group 14 are in reverse optical power matching. Meeting the above conditions is conducive to achieving high magnification, improving the performance of the overall optical system, and thus providing more image details when shooting at a distance.

[0055] Optionally, an intermediate image plane is formed between the tenth lens 110 and the eleventh lens 111; the length from the midpoint of the object side of the first lens 101 to the center of the intermediate image plane is THA, and the length from the center of the intermediate image plane to the center of the aperture stop STO is THB; wherein, 1.1 < THA / THB < 1.3.

[0056] By limiting the distance ratios between the front lens and the aperture stop STO and the intermediate image plane, the optical system can achieve a high magnification while maintaining a short overall optical length, thereby reducing the size of the external lens and achieving better portability.

[0057] Optionally, the optical power of the second lens group 12 is... B; Lens 106 (sixth lens), 107 (seventh lens), 108 (eighth lens), 109 (ninth lens), and 110 (tenth lens) form the first sub-lens group. The optical power of the first sub-lens group is... 6~10; The eleventh lens 111 and the twelfth lens 112 are cemented together to form the fourth cemented doublet lens group, and the optical power of the fourth cemented doublet lens group is... 11~12; where 1.3 < 6~10 / B+ 11~12 / B < 1.5.

[0058] By rationally allocating the optical power of the second lens group 12, the first sub-lens group, and the fourth cemented doublet lens group, the above conditions are met, tolerance sensitivity is reduced, and the overall yield of the optical system is effectively improved.

[0059] Optionally, the optical power of the third lens group 14 is... C, the optical power of the thirteenth lens 113 is 13, the optical power of the fourteenth lens 114 is 14; where 0.9 < 13 / C+ 14 / C < 1.2.

[0060] By rationally allocating the optical power of the third lens group 14, the thirteenth lens 113, and the fourteenth lens 114, the above conditions are met, field curvature is corrected, and the resolution of the optical system is improved.

[0061] Optionally, the optical power of the first cemented doublet lens group is 1~2; ​​The optical power of the first lens 101 is 1. The optical power of the second lens 102 is 2. The Abbe number of the first lens 101 is vd1, and the Abbe number of the second lens 102 is vd2; the optical power of the second cemented doublet lens group is... φ3~4; the optical power of the third lens 103 is 3. The optical power of the fourth lens 104 is 4. The Abbe number of the third lens 103 is vd3, and the Abbe number of the fourth lens 104 is vd4; the optical power of the fourth cemented doublet lens group is... 11~12; The optical power of the eleventh lens 111 is 11. The optical power of the twelfth lens 112 is 12. The Abbe number of the eleventh lens 111 is vd11, and the Abbe number of the twelfth lens 112 is vd12; where 1000×| 1+ 2- 1~2|<0.55, 1000×|( 1 / vd1+ 2 / vd2)|<0.65;100×| 3+ 4- 3~4|<0.25, 1000×|( 3 / vd3+ 4 / vd4)|<0.6;100×| 11+ 12- 11~12|<0.3, 1000×|( 11 / vd11+ 12 / vd12)|<0.9.

[0062] The optical power of the first cemented doublet lens group, the optical power of the first lens 101, the optical power of the second lens 102, the Abbe number of the first lens 101, and the Abbe number of the second lens 102 are set to satisfy 1000×| 1+ 2- 1~2|<0.55, 1000×|( 1 / vd1+ A value of 2 / vd2)<0.65 is beneficial for the first cemented doublet lens group to effectively correct chromatic aberration in the optical system, thereby improving the resolution of the optical system. The optical power of the second cemented doublet lens group, the optical power of the third lens 103, the optical power of the fourth lens 104, the Abbe number of the third lens 103, and the Abbe number of the fourth lens 104 are set to satisfy 100×| 3+ 4- 3~4|<0.25, 1000×|( 3 / vd3+ A value of 4 / vd4)<0.6 is beneficial for the second cemented doublet lens group to effectively correct chromatic aberration in the optical system, thereby improving the resolution of the optical system. The optical power of the fourth cemented doublet lens group, the optical power of the eleventh lens 111, the optical power of the twelfth lens 112, the Abbe number of the eleventh lens 111, and the Abbe number of the twelfth lens 112 are set to satisfy 100×| 11+ 12- 11~12|<0.3, 1000×|( 11 / vd11+ The value of 12 / vd12)<0.9 is beneficial for the fourth cemented doublet lens group to exert its ability to correct chromatic aberration in the optical system, thereby improving the resolution of the optical system.

[0063] Optionally, the refractive index of the fifth lens 105 is nd5, and the refractive index of the sixth lens 106 is nd6; where 3.7 < nd5 + nd6 < 3.95.

[0064] By rationally setting the refractive index of the fifth lens 105 and the refractive index of the sixth lens 106, the fifth lens 105 and the sixth lens 106 are made of high emissivity materials, the radius of curvature of the lens is increased, the lens is more flat, which is conducive to the smooth transition of light and reduces the incident and exit angles of light on the lens surface, thereby improving the lens assembly yield.

[0065] Optionally, the Abbe number of the seventh lens 107 is vd7, the Abbe number of the twelfth lens 112 is vd12, and the focal length of the second lens group 12 is fB; the seventh lens 107 and the eighth lens 108 are cemented together to form a third cemented doublet lens group, and the focal length of the third cemented doublet lens group is f7~8; the eleventh lens 111 and the twelfth lens 112 are cemented together to form a fourth cemented doublet lens group, and the focal length of the fourth cemented doublet lens group is f11~12; wherein, 100 < vd7 + vd12 < 120; 0.5 < f7~8 / fB + f11~12 / fB < 1.

[0066] Among them, setting the Abbe number of the seventh lens 107 and the twelfth lens 112 in a reasonable manner, as well as setting the ratio between the focal length of the third cemented doublet lens group, the focal length of the fourth cemented doublet lens group and the focal length of the second lens group 12, are beneficial to the correction of transverse chromatic aberration of the optical system and improve the resolution of the system.

[0067] Optionally, the maximum half-aperture of the lens in the teleconverter is SDM, the maximum half-image height of the teleconverter is H, the distance from the midpoint of the object side surface of the first lens 101 to the midpoint of the image side surface of the fourteenth lens 114 is TTL, and the focal length of the teleconverter is f; where 1.5 < SDM / H < 1.7; -2.4 < TTL / f < -2.2.

[0068] By setting the aforementioned proportional relationship, the structural dimensions and optical performance are synergistically optimized. A reasonable range for the SDM / H value ensures sufficient light transmission aperture, suppresses vignetting to guarantee uniform imaging across the entire image height, and avoids excessive volume redundancy due to an overly large lens aperture. Within the TTL / f ratio range, it prevents excessive light refraction and aberration correction difficulties caused by an excessively short total length, while also avoiding compromises in portability due to excessive structural length. This helps reduce the overall size and weight of the optical system, improves the teleconverter's portability, and reduces lens material costs.

[0069] Therefore, this embodiment of the invention uses 14 lenses and 2 right-angle prisms. By reasonably setting the optical power of each lens and the position of the right-angle prisms, the total length of the teleconverter lens is 112mm, the magnification is about 2.35x, the optical distortion is less than 2%, the image square F# is 3.14, and the maximum full-image height of the lens is 11.44mm. Its size and weight are portable and controllable, and it can achieve high-magnification optical zoom while ensuring image quality, so as to meet higher usage requirements.

[0070] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of the teleconverter lens applicable to the above-described embodiments.

[0071] Example 1

[0072] Continue to refer to Figure 1 The teleconverter lens includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, a fifth lens 105, a first right-angle prism 1101, a sixth lens 106, a seventh lens 107, an eighth lens 108, a ninth lens 109, a tenth lens 110, an eleventh lens 111, a twelfth lens 112, a second right-angle prism 1301, a thirteenth lens 113, a fourteenth lens 114, and an aperture stop STO, arranged sequentially along the optical axis from the object plane to the image plane. The first lens 101 and the second lens 102 are cemented together to form a first cemented doublet lens group; the third lens 103 and the fourth lens 104 are cemented together to form a second cemented doublet lens group; the seventh lens 107 and the eighth lens 108 are cemented together to form a third cemented doublet lens group; and the eleventh lens 111 and the twelfth lens 112 are cemented together to form a fourth cemented doublet lens group. For example, Table 1 details the specific optical physical parameters of each lens in the teleconverter provided in Embodiment 1 of the present invention, according to a feasible implementation.

[0073] Table 1 Design values ​​of optical physical parameters for teleconverter lenses

[0074]

[0075] The surface numbers in Table 1 are assigned according to the surface sequence of each lens. "S1" represents the object-side surface of the first lens 101, "S2" represents the image-side surface of the first lens 101, and so on. "STO" represents the aperture stop. The radius of curvature represents the curvature of the lens surface; a positive value indicates the surface bends towards the image plane, a negative value indicates the surface bends towards the object plane, and "Infinity" indicates the surface is flat with an infinite radius of curvature. Thickness represents the central axial distance from the object-side surface to the next surface. Refractive index represents the ability of the material between the object-side surface and the next surface to deflect light; a blank space indicates the current location is air with a refractive index of 1. The Abbe number represents the dispersion characteristics of the material between the object-side surface and the next surface. dPgF represents local dispersion, a parameter measuring the dispersion characteristics of a material, a core parameter for correcting second-order spectral aberration (second-order chromatic aberration), and a key indicator for apochromatic lens design.

[0076] The teleconverter lens in this embodiment achieves the following technical specifications: half-image height H is 5.72mm, TTL is 117.7mm, and lens focal length f is -52.816mm.

[0077] Figure 2 The visible light band full-frequency MTF diagram of a teleconverter lens provided in Embodiment 1 of the present invention is as follows: Figure 2 As shown, the vertical axis represents the modulation transfer function (MTF) value, and the horizontal axis represents the frequency. The simulated wavelength range is 470 nm to 650 nm. Figure 2 It can be seen that the modulation transfer function values ​​of each frequency under different fields of view are all controlled within a reasonable range. The modulation transfer function values ​​in the entire field of view are all greater than 0.3 in the 200 lp / mm frequency band, indicating that the image quality of the teleconverter is well controlled.

[0078] Figure 3 This is a chromatic aberration curve of a teleconverter lens provided in Embodiment 1 of the present invention, as shown in the figure. Figure 3 As shown, the vertical direction represents the normalized aperture, 0 indicates being on the optical axis, and the vertex in the perpendicular direction represents the maximum pupil radius; the horizontal direction represents the offset relative to the dominant wavelength, in micrometers (μm). Figure 3 It can be seen that the axial aberration of the normalized aperture is controlled within a reasonable range at different wavelengths (650nm, 610nm, 550nm, 510nm, 470nm, 435nm), indicating that the axial chromatic aberration of the teleconverter lens is well controlled and meets the usage requirements.

[0079] Figure 4 The field curvature and distortion diagram of a teleconverter lens provided in Embodiment 1 of the present invention is as follows: Figure 4As shown, in the coordinate system on the left side of the figure, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the arc loss; from Figure 4 It can be seen that the lens provided in this embodiment effectively controls field curvature at a wavelength of 550nm, meaning that during imaging, the difference in image quality between the center and the periphery is small; in the coordinate system on the right, the horizontal axis represents the magnitude of distortion, expressed as a percentage; the vertical axis represents the normalized image height, which has no unit. Figure 4 As can be seen, the distortion of the lens provided in this embodiment has been well corrected, with F-theta distortion less than 0.5% and low imaging distortion.

[0080] Example 2

[0081] Figure 5 This is a schematic diagram of the structure of a teleconverter lens provided in Embodiment 2 of the present invention, as shown below. Figure 5 As shown, the teleconverter lens includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, a fifth lens 105, a first right-angle prism 1101, a sixth lens 106, a seventh lens 107, an eighth lens 108, a ninth lens 109, a tenth lens 110, an eleventh lens 111, a twelfth lens 112, a second right-angle prism 1301, a thirteenth lens 113, a fourteenth lens 114, and an aperture stop STO, arranged sequentially along the optical axis from the object plane to the image plane. The first lens 101 and the second lens 102 are cemented together to form a first cemented doublet lens group; the third lens 103 and the fourth lens 104 are cemented together to form a second cemented doublet lens group; the seventh lens 107 and the eighth lens 108 are cemented together to form a third cemented doublet lens group; and the eleventh lens 111 and the twelfth lens 112 are cemented together to form a fourth cemented doublet lens group. For example, Table 2 details the specific optical physical parameters of each lens in the teleconverter lens provided in Embodiment 2 of the present invention, according to a feasible implementation.

[0082] Table 2 Design values ​​of optical physical parameters for teleconverter lenses

[0083]

[0084] The surface numbers in Table 2 are assigned according to the surface sequence of each lens. "S1" represents the object-side surface of the first lens 101, "S2" represents the image-side surface of the first lens 101, and so on. "STO" represents the aperture stop. The radius of curvature represents the curvature of the lens surface; a positive value indicates the surface bends towards the image plane, a negative value indicates the surface bends towards the object plane, and "Infinity" indicates the surface is flat with an infinite radius of curvature. Thickness represents the central axial distance from the object-side surface to the next surface. Refractive index represents the ability of the material between the object-side surface and the next surface to deflect light; a blank space indicates the current location is air with a refractive index of 1. The Abbe number represents the dispersion characteristics of the material between the object-side surface and the next surface. dPgF represents local dispersion, a parameter measuring the dispersion characteristics of a material, a core parameter for correcting second-order spectral aberration (second-order chromatic aberration), and a key indicator for apochromatic lens design.

[0085] The teleconverter lens in this second embodiment achieves the following technical specifications: half-image height H is 5.72mm, TTL is 117.77mm, and lens focal length f is -52.787mm.

[0086] Figure 6 The visible light band full-frequency MTF diagram of a teleconverter lens provided in Embodiment 2 of the present invention is as follows: Figure 6 As shown, the vertical axis represents the modulation transfer function (MTF) value, and the horizontal axis represents the frequency. The simulated wavelength range is 470 nm to 650 nm. Figure 6 It can be seen that the modulation transfer function values ​​of each frequency under different fields of view are all controlled within a reasonable range. The modulation transfer function values ​​in the entire field of view are all greater than 0.3 in the 200 lp / mm frequency band, indicating that the image quality of the teleconverter is well controlled.

[0087] Figure 7 This is a chromatic aberration curve of a teleconverter lens provided in Embodiment 2 of the present invention, as shown in the figure. Figure 7 As shown, the vertical direction represents the normalized aperture, 0 indicates being on the optical axis, and the vertex in the perpendicular direction represents the maximum pupil radius; the horizontal direction represents the offset relative to the dominant wavelength, in micrometers (μm). Figure 7 It can be seen that the axial aberration of the normalized aperture is controlled within a reasonable range at different wavelengths (650nm, 610nm, 550nm, 510nm, 470nm, 435nm), indicating that the axial chromatic aberration of the teleconverter lens is well controlled and meets the usage requirements.

[0088] Figure 8 This is a field curvature and distortion diagram of a teleconverter lens provided in Embodiment 2 of the present invention, as shown below. Figure 8As shown, in the coordinate system on the left side of the figure, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the arc loss; from Figure 8 It can be seen that the lens provided in this embodiment effectively controls field curvature at a wavelength of 550nm, meaning that during imaging, the difference in image quality between the center and the periphery is small; in the coordinate system on the right, the horizontal axis represents the magnitude of distortion, expressed as a percentage; the vertical axis represents the normalized image height, which has no unit. Figure 8 As can be seen, the distortion of the lens provided in this embodiment has been well corrected, with F-theta distortion less than 0.1% and low imaging distortion.

[0089] Example 3

[0090] Figure 9 This is a schematic diagram of the structure of a teleconverter lens provided in Embodiment 3 of the present invention, as shown below. Figure 9 As shown, the teleconverter lens includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, a fifth lens 105, a first right-angle prism 1101, a sixth lens 106, a seventh lens 107, an eighth lens 108, a ninth lens 109, a tenth lens 110, an eleventh lens 111, a twelfth lens 112, a second right-angle prism 1301, a thirteenth lens 113, a fourteenth lens 114, and an aperture stop STO, arranged sequentially along the optical axis from the object plane to the image plane. The first lens 101 and the second lens 102 are cemented together to form a first cemented doublet lens group; the third lens 103 and the fourth lens 104 are cemented together to form a second cemented doublet lens group; the seventh lens 107 and the eighth lens 108 are cemented together to form a third cemented doublet lens group; and the eleventh lens 111 and the twelfth lens 112 are cemented together to form a fourth cemented doublet lens group. For example, Table 3 details the specific optical physical parameters of each lens in the teleconverter lens provided in Embodiment 3 of the present invention, according to a feasible implementation.

[0091] Table 3 Design values ​​of optical physical parameters for teleconverter lenses

[0092]

[0093] The surface numbers in Table 3 are assigned according to the surface sequence of each lens. "S1" represents the object-side surface of the first lens 101, "S2" represents the image-side surface of the first lens 101, and so on. "STO" represents the aperture stop. The radius of curvature represents the curvature of the lens surface; a positive value indicates the surface bends towards the image plane, a negative value indicates the surface bends towards the object plane, and "Infinity" indicates the surface is flat with an infinite radius of curvature. Thickness represents the central axial distance from the object-side surface to the next surface. Refractive index represents the ability of the material between the object-side surface and the next surface to deflect light; a blank space indicates the current location is air with a refractive index of 1. The Abbe number represents the dispersion characteristics of the material between the object-side surface and the next surface. dPgF represents local dispersion, a parameter measuring the dispersion characteristics of a material, a core parameter for correcting second-order spectral aberration (second-order chromatic aberration), and a key indicator for apochromatic lens design.

[0094] The teleconverter lens in this embodiment three achieves the following technical specifications: half-image height H is 5.72mm, TTL is 117.77mm, and lens focal length f is -52.761mm.

[0095] Figure 10 The visible light band full-frequency MTF diagram of a teleconverter lens provided in Embodiment 3 of the present invention is as follows: Figure 10 As shown, the vertical axis represents the modulation transfer function (MTF) value, and the horizontal axis represents the frequency. The simulated wavelength range is 470 nm to 650 nm. Figure 10 It can be seen that the modulation transfer function values ​​of each frequency under different fields of view are all controlled within a reasonable range. The modulation transfer function values ​​in the entire field of view are all greater than 0.3 in the 200 lp / mm frequency band, indicating that the image quality of the teleconverter is well controlled.

[0096] Figure 11 This is a chromatic aberration curve of a teleconverter lens provided in Embodiment 3 of the present invention, as shown in the figure. Figure 11 As shown, the vertical direction represents the normalized aperture, 0 indicates being on the optical axis, and the vertex in the perpendicular direction represents the maximum pupil radius; the horizontal direction represents the offset relative to the dominant wavelength, in micrometers (μm). Figure 11 It can be seen that the axial aberration of the normalized aperture is controlled within a reasonable range at different wavelengths (650nm, 610nm, 550nm, 510nm, 470nm, 435nm), indicating that the axial chromatic aberration of the teleconverter lens is well controlled and meets the usage requirements.

[0097] Figure 12 The field curvature and distortion diagram of a teleconverter lens provided in Embodiment 3 of the present invention is as follows: Figure 12As shown, in the coordinate system on the left side of the figure, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the arc loss; from Figure 12 It can be seen that the lens provided in this embodiment effectively controls field curvature at a wavelength of 550nm, meaning that during imaging, the difference in image quality between the center and the periphery is small; in the coordinate system on the right, the horizontal axis represents the magnitude of distortion, expressed as a percentage; the vertical axis represents the normalized image height, which has no unit. Figure 12 As can be seen, the distortion of the lens provided in this embodiment has been well corrected, with F-theta distortion less than 0.5% and low imaging distortion.

[0098] To provide a clearer explanation of the above embodiments, Table 4 details the specific optical physical parameters of each lens in the teleconverter provided in Embodiments 1 to 3 of the present invention, as well as other feasible optical physical parameters.

[0099] Table 4 Design values ​​of optical physical parameters for teleconverter lenses

[0100]

[0101] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A teleconverter lens, characterized in that, The teleconverter lens comprises a first lens group, a first reflecting element, a second lens group, a second reflecting element, a third lens group, and an aperture stop, arranged sequentially along the optical axis from the object plane to the image plane; the teleconverter lens has fourteen lenses with optical power. The first lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially along the optical axis from the object plane to the image plane; The second lens group includes a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, and a twelfth lens arranged sequentially along the optical axis from the object plane to the image plane; The third lens group includes a thirteenth lens and a fourteenth lens arranged sequentially along the optical axis from the object plane to the image plane; The first reflective element includes a first right-angle prism, which is located between the fifth lens and the sixth lens; The second reflective element includes a second right-angle prism, which is located between the twelfth lens and the thirteenth lens; The first lens has positive optical power, the second lens has negative optical power, the third lens has positive optical power, the fourth lens has negative optical power, the fifth lens has positive optical power, the sixth lens has positive optical power, the seventh lens has positive optical power, the eighth lens has negative optical power, the ninth lens has negative optical power, the tenth lens has positive optical power, the eleventh lens has negative optical power, the twelfth lens has positive optical power, the thirteenth lens has positive optical power, and the fourteenth lens has positive optical power; the focal length of the teleconverter is f, the focal length of the first lens group is fA, the focal length of the second lens group is fB, and the focal length of the third lens group is fC; Where -2.9 < fA / f + fB / f + fC / f < -2.

6.

2. The teleconverter lens according to claim 1, characterized in that, The first lens and the second lens are cemented together to form a first cemented doublet lens group; the third lens and the fourth lens are cemented together to form a second cemented doublet lens group; the seventh lens and the eighth lens are cemented together to form a third cemented doublet lens group; and the eleventh lens and the twelfth lens are cemented together to form a fourth cemented doublet lens group.

3. The teleconverter lens according to claim 1, characterized in that, An intermediate image plane is formed between the tenth lens and the eleventh lens; the length from the midpoint of the object side of the first lens to the center of the intermediate image plane is THA, and the length from the center of the intermediate image plane to the center of the aperture is THB. Among them, 1.1 < THA / THB < 1.

3.

4. The teleconverter lens according to claim 1, characterized in that, The optical power of the second lens group is B; The sixth lens, the seventh lens, the eighth lens, the ninth lens, and the tenth lens constitute a first sub-lens group, and the optical power of the first sub-lens group is... 6~10; The eleventh lens and the twelfth lens are cemented together to form a fourth cemented doublet lens group, and the optical power of the fourth cemented doublet lens group is... 11~12; Among them, 1.3 < 6~10 / B+ 11~12 / B < 1.

5.

5. The teleconverter lens according to claim 1, characterized in that, The optical power of the third lens group is: C, the optical power of the thirteenth lens is 13, the optical power of the fourteenth lens is 14; Among them, 0.9 < 13 / C+ 14 / C < 1.

2.

6. The teleconverter lens according to claim 2, characterized in that, The optical power of the first cemented doublet lens group is 1~2; ​​the optical power of the first lens is 1. The optical power of the second lens is 2. The Abbe number of the first lens is vd1, and the Abbe number of the second lens is vd2; the optical power of the second cemented doublet lens group is... 3~4; the optical power of the third lens is 3. The optical power of the fourth lens is 4. The Abbe number of the third lens is vd3, and the Abbe number of the fourth lens is vd4; The optical power of the fourth cemented doublet lens group is: 11~12; The optical power of the eleventh lens is 11. The optical power of the twelfth lens is 12, the Abbe number of the eleventh lens is vd11, and the Abbe number of the twelfth lens is vd12; wherein, 1000×| 1+ 2- 1~2|<0.55mm -1 , 1000×|( 1 / vd1+ 2 / vd2)|<0.65mm -1 ; 100×| 3+ 4- 3~4|<0.25mm -1 , 1000×|( 3 / vd3+ 4 / vd4)|<0.6mm -1 ; 100×| 11+ 12- 11~12|<0.3mm -1 , 1000×|( 11 / vd11+ 12 / vd12)|<0.9mm -1 .

7. The teleconverter lens according to claim 1, characterized in that, The refractive index of the fifth lens is nd5, and the refractive index of the sixth lens is nd6; Among them, 3.7 < nd5 + nd6 < 3.

95.

8. The teleconverter lens according to claim 1, characterized in that, The seventh lens has an Abbe number of vd7, the twelfth lens has an Abbe number of vd12, and the focal length of the second lens group is fB; the seventh lens and the eighth lens are cemented together to form a third cemented doublet lens group, and the focal length of the third cemented doublet lens group is f7~8; the eleventh lens and the twelfth lens are cemented together to form a fourth cemented doublet lens group, and the focal length of the fourth cemented doublet lens group is f11~12. Among them, 100 < vd7 + vd12 < 120; 0.5 < f7~8 / fB + f11~12 / fB < 1.

9. The teleconverter lens according to claim 1, characterized in that, The teleconverter has a maximum half-aperture of SDM, a maximum half-image height of H, a distance of TTL from the midpoint of the object side of the first lens to the midpoint of the image side of the fourteenth lens, and a focal length of f. Among them, 1.5 < SDM / H < 1.7; -2.4 < TTL / f < -2.2.

Images