An 8000-mega-pixel low-distortion lens

Abstract

The application relates to the technical field of optical lenses, in particular to an 8000-megapixel low-distortion lens which comprises an integral lens unit and a focusing adjusting mechanism. The integral lens unit rigidly fixes at least eight lens elements in the interior as a whole; the focusing adjusting mechanism drives the lens unit as a single whole to translate along the optical axis to realize focusing. In the optical aspect, the lens innovatively adopts a global surface lens to form an eight-piece improved double Gauss structure, and strategically selects high refractive index, special dispersion glass and sets two achromatic cemented lenses to replace expensive aspherical lenses to accurately correct aberration. Through the above-mentioned optical and mechanical collaborative design, the application can ensure 8000-megapixel high resolution, cover a large imaging circle of medium format and have super low distortion performance, significantly simplify the mechanical structure, reduce the manufacturing cost, and greatly improve the reliability and stability of the lens.

Description

Technical Field

[0001] This utility model relates to the field of optical lens technology, and in particular to an 80-megapixel low-distortion lens. Background Technology

[0002] With the advancement of CMOS sensor technology, the requirements for imaging lenses in high-end manufacturing, aerospace remote sensing, and other fields are increasingly demanding. Lenses not only need to be compatible with high-resolution sensors with tens of millions or even hundreds of millions of pixels, but also require extremely low distortion (e.g., below 0.1%) and high modulation transfer function (MTF) across the entire field of view. To achieve these goals, existing technologies face irreconcilable technical contradictions, primarily manifested in the two mainstream focusing structures:

[0003] The first type is a complex floating or internal focusing structure. This structure can dynamically compensate for aberrations to ensure high image quality at various focusing distances, but its structure is complex, costly, and has poor vibration resistance, making it difficult to meet industrial-grade reliability requirements. The second type is a simple overall translation focusing structure. This structure is robust, reliable, and low-cost, but it cannot compensate for aberration changes during focusing and cannot support high-resolution applications above 50 megapixels.

[0004] In summary, existing technologies are caught in a dilemma: pursuing ultimate optical performance requires sacrificing the reliability of the mechanical structure; while pursuing high reliability requires sacrificing the upper limit of optical performance.

[0005] Based on the above, this invention proposes an 80-megapixel low-distortion lens, which can effectively solve the above problems. Utility Model Content

[0006] To address the problem that existing high-pixel low-distortion lenses generally rely on complex floating or internal focusing structures to compensate for aberrations, resulting in high manufacturing costs and complex mechanical structures, this application proposes an 80-megapixel low-distortion lens.

[0007] An 80-megapixel low-distortion lens, comprising:

[0008] An integral lens unit comprising at least eight lens elements arranged sequentially along an optical axis and a plurality of spacers for separating the lens elements from each other, wherein the at least eight lens elements and the spacers are rigidly fixed together; and

[0009] A focus adjustment mechanism, including:

[0010] A main lens barrel, wherein the integral lens unit is fixed as a rigid whole within the main lens barrel;

[0011] A lens mounting interface is configured to remain fixed relative to the camera body during focusing; the main lens barrel is threaded into the lens mounting interface, such that by rotating the main lens barrel, the main lens barrel, together with the integral lens group unit inside it, can be driven as a single unit to translate along the optical axis relative to the lens mounting interface to achieve focusing. This integral translation focusing mechanical structure fundamentally simplifies the design, improves the lens's vibration resistance and long-term stability, while reducing manufacturing costs and assembly difficulty.

[0012] In one embodiment, the eight lens elements, from the image side to the object side, are designated as a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element, a seventh lens element, and an eighth lens element. To achieve excellent aberration correction without using aspherical lenses, this application precisely defines the lens materials: the refractive index of the first lens element is between 1.85 and 1.95, the Abbe number of the first lens element is between 30 and 40, the refractive index of the eighth lens element is between 1.50 and 1.55, the Abbe number of the eighth lens element is greater than 63, and the plurality of lens elements also satisfy at least three of the following conditions;

[0013] (a) The refractive index of the second lens element is between 1.72 and 1.80, and the Abbe number is between 24 and 30;

[0014] (b) The refractive index of the third lens element is between 1.60 and 1.65, and the Abbe number is less than 30;

[0015] (c) The refractive index of the fourth lens element is greater than 1.90, and the Abbe number is between 20 and 22;

[0016] (d) The refractive indices of the fifth, sixth, and seventh lens elements are between 1.60 and 1.70, and both Abbe numbers in the fifth and seventh lens elements are greater than 60. By strategically combining the optical properties (refractive index and Abbe number) of the eight aspherical lens materials, a highly efficient aberration self-compensation system is formed, accurately balancing various aberrations such as spherical aberration, coma, and chromatic aberration. This replaces expensive aspherical lenses, achieving high resolution at the 80-megapixel level while controlling costs.

[0017] In one embodiment, the first lens element is a meniscus lens with positive optical power, the second lens element is a biconcave lens with negative optical power, the third lens element is a biconvex lens with positive optical power, the fourth lens element is a biconvex lens with positive optical power, the fifth lens element is a biconcave lens with negative optical power, the sixth lens element is a biconvex lens with positive optical power, the seventh lens element is a meniscus lens with positive optical power, and the eighth lens element is a meniscus lens with negative optical power. The specific optical power and shape distribution of the eight lenses can efficiently correct field curvature and astigmatism, ensuring excellent imaging quality from the center to the edge of the field of view.

[0018] In one embodiment, the image side of the integral lens unit is also provided with protective glass, which effectively protects the integral lens unit from damage caused by external environment such as dust and scratches, and improves the durability of the lens.

[0019] In one embodiment, the first lens element is made of high-refractive-index, low-dispersion glass, and the fourth lens element is made of high-refractive-index, high-dispersion glass. The high refractive index of the first lens element enables it to achieve the required optical power with a relatively gentle curvature, reducing spherical aberration at its source. The strong light deflection capability and unique high dispersion characteristics of the fourth lens element are used to powerfully correct residual aberrations and secondary spectra in the system, achieving fine control over the overall image quality.

[0020] In one embodiment, the second and third lens elements are cemented together to form a first achromatic cemented lens, and the fifth and sixth lens elements are cemented together to form a second achromatic cemented lens. By setting two sets of achromatic cemented lenses and utilizing the combination of glass with different dispersion characteristics, axial chromatic aberration and magnification chromatic aberration are greatly corrected, ensuring the true reproduction of image colors; at the same time, the cementing design also reduces the air-glass contact area and improves light transmittance. In a particular embodiment, the radius of curvature, thickness, focal length, and material of the two cemented lenses can be designed to be identical, thereby achieving component sharing and greatly reducing production and inventory costs.

[0021] In one embodiment, the absolute value of optical distortion of the lens's optical system is strictly controlled to less than 0.1% across the entire field of view, achieving extremely low image geometric distortion and ensuring that the lines and shapes of the subject can be accurately reproduced.

[0022] In one embodiment, the ratio of the total optical length (TTL) to the effective focal length (EFL) of the integral lens unit (TTL / EFL) is designed to be in the range of 1.2 to 1.8. This ensures coverage of the large image circle and long back working distance of medium format while achieving a relatively compact lens structure, making it easy to integrate into various industrial equipment or camera systems, thus balancing high performance and practicality.

[0023] In one embodiment, the present application further includes a locking ring and a mounting locking screw. After precise focusing is achieved by rotating the main lens barrel, the mounting locking screw can be tightened. This screw applies pressure to the main lens barrel through the locking ring, firmly locking its position relative to the lens mounting interface. This effectively prevents focus shift in industrial environments such as vibration or accidental contact, ensuring stability during long-term operation and accuracy of measurement results.

[0024] In one embodiment, to optimize manufacturing and assembly processes, the main lens barrel includes an object-side lens barrel, an image-side lens barrel, a fixing sleeve, and at least one connecting screw. The fixing sleeve is fitted onto the rear half of the object-side lens barrel, and the connecting screw passes through the fixing sleeve and the object-side lens barrel, ultimately screwing into the image-side lens barrel, thereby securely connecting the front object-side lens barrel assembly and the rear image-side lens barrel assembly into a complete main lens barrel.

[0025] In one embodiment, the integral lens unit further includes an aperture structure, which is positioned at approximately the center of symmetry of the optical system, specifically between the third lens element and the fourth lens element, and can effectively correct distortion and control relative illumination.

[0026] In one embodiment, the aperture structure includes a manually rotatable aperture adjustment cylinder and a manual aperture assembly that adjusts the aperture size as the aperture adjustment cylinder rotates. The aperture adjustment cylinder is movably fitted onto the outside of the image-square lens barrel, and the manual aperture assembly is disposed inside the image-square lens barrel. An arc-shaped annular limiting groove is machined on the outer wall of the image-square lens barrel, and a limiting pin passes through the cylinder wall of the aperture adjustment cylinder and engages in the limiting groove. This structure ensures that the aperture adjustment cylinder can only rotate smoothly within a preset angle range (i.e., adjusting the manual aperture assembly from the maximum aperture to the minimum aperture). Once the aperture value is set, a dimming locking screw can be used to press and lock the aperture adjustment cylinder relative to the image-square lens barrel, thereby preventing the aperture value from changing due to vibration or accidental touch.

[0027] This application provides an 80-megapixel low-distortion lens, which achieves the following technical effects:

[0028] 1. By adopting an integral lens group unit with overall translation focusing and a simple focus locking mechanism, the lens manufacturing and assembly process is simplified, production costs are significantly reduced, and the lens has excellent vibration and shock resistance, ensuring focus stability and system reliability for long-term use in harsh industrial environments.

[0029] 2. By employing eight global surface lenses, high-refractive-index special dispersive glass, and achromatic cemented lenses, expensive aspherical lenses were successfully replaced. While ensuring high resolution (80 megapixels), a large image circle covering medium format, and excellent optical performance with ultra-low distortion (below 0.1%), high reliability and low cost of the mechanical structure were achieved, effectively resolving the contradiction between high performance, high reliability, and low cost in existing technologies. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of an 80-megapixel low-distortion lens provided in an embodiment of this application.

[0031] Figure 2 This is a cross-sectional view of an 80-megapixel low-distortion lens provided in an embodiment of this application.

[0032] Figure 3 This is a diagram illustrating the optical lens parameters of an 80-megapixel low-distortion lens provided in an embodiment of this application.

[0033] Figure 4 This is an optical path diagram of an optical lens in an 80-megapixel low-distortion lens provided in an embodiment of this application.

[0034] Figure 5 This is an exploded view of an 80-megapixel low-distortion lens provided in an embodiment of this application.

[0035] Figure 6 This is a schematic diagram of the object-side lens barrel in an 80-megapixel low-distortion lens provided in an embodiment of this application.

[0036] Figure 7 This is a schematic diagram of the image-side lens barrel in an 80-megapixel low-distortion lens provided in an embodiment of this application.

[0037] Figure 8 This is a schematic diagram of the aperture structure in an 80-megapixel low-distortion lens provided in an embodiment of this application.

[0038] Figure 9 This is a schematic diagram illustrating the changes in lens distortion in an 80-megapixel low-distortion lens provided in an embodiment of this application.

[0039] Figure 10This is a schematic diagram of the MTF modulation function curve change of an 80-megapixel low-distortion lens provided in an embodiment of this application.

[0040] Figure 11 This is a schematic diagram of the relative illumination of a lens in an 80-megapixel low-distortion lens provided in an embodiment of this application.

[0041] Explanation of reference numerals in the attached figures:

[0042] 1. Integral lens unit; 11. Lens element; 111. First lens element; 112. Second lens element; 113. Third lens element; 114. Fourth lens element; 115. Fifth lens element; 116. Sixth lens element; 117. Seventh lens element; 118. Eighth lens element; 119. Protective glass; 12. Spacer; 121. First spacer; 122. Second spacer; 123. Third spacer; 124. Fourth spacer; 13. Aperture structure; 131. Aperture adjustment cylinder; 1311. Groove; 132. Manual aperture assembly; 1321. Blade; 1322. Protrusion; 133. Dimming locking screw; 134. Limiting pin;

[0043] 2. Focusing adjustment mechanism; 21. Main lens barrel; 211. Object-side lens barrel; 2111. Front end retaining ring; 212. Image-side lens barrel; 2121. Rear end retaining ring; 2122. Annular limiting groove; 213. Fixing cylinder; 214. Connecting screw; 215. Focusing thread; 22. Lens mounting interface; 221. First interface; 222. Second interface; 223. Third interface; 23. Locking retaining ring; 24. Installation locking screw. Detailed Implementation

[0044] The following is in conjunction with the appendix Figure 1-10 This application provides a further detailed description of an 80-megapixel low-distortion lens.

[0045] This application provides an 80-megapixel low-distortion lens, which includes an integral lens group unit 1 and a focus adjustment mechanism 2.

[0046] In this embodiment, the integral lens unit 1 includes at least eight lens elements 11 arranged sequentially along the optical axis and a plurality of spacers 12 for separating the lens elements 11 from each other, and the at least eight lens elements 11 and the spacers 12 are rigidly fixed together. In this embodiment, the lens elements 11 are preferably eight, and are arranged sequentially from the object side to the image side along the optical axis as follows: first lens element 111, second lens element 112, third lens element 113, fourth lens element 114, fifth lens element 115, sixth lens element 116, seventh lens element 117 and eighth lens element 118, and all lens elements 11 are spherical lenses.

[0047] Specifically, in this embodiment, there are preferably four spacers 12, namely a first spacer 121 between the first lens element 111 and the second lens element 112, a second spacer 122 between the fourth lens element 114 and the fifth lens element 115, a third spacer 123 between the sixth lens element 116 and the seventh lens element 117, and a fourth spacer 124 between the seventh lens element 117 and the eighth lens element 118.

[0048] In this embodiment, the end of the integral lens unit 1 along the optical axis is also provided with a protective glass 119 to protect the eight lens elements 11 at the front end.

[0049] In this embodiment, the specific optical power and shape allocation of the eight lens elements 11 are as follows, forming a modified symmetrical double Gaussian structure:

[0050] The first lens element 111 is a positive focal length meniscus, which initially converges the incident light rays.

[0051] The second lens element 112 is a negative optical power biconcave mirror, which is cemented together with the third lens element 113.

[0052] The third lens element 113 is a positive power biconvex lens. The first achromatic cemented lens, composed of the second lens element 112 and the third lens element 113, is responsible for correcting chromatic aberration and spherical aberration.

[0053] An aperture is positioned between L3 and L4, at approximately the center of symmetry of the optical system, which is crucial for effectively correcting transverse aberrations such as distortion and coma.

[0054] The fourth lens element 114 is a positive optical power biconvex lens.

[0055] The fifth lens element 115 is a negative optical power biconcave mirror, which is cemented together with the sixth lens element 116.

[0056] The sixth lens element 116 is a positive power biconvex lens. The second achromatic cemented lens, composed of the fifth lens element 115 and the sixth lens element 116, is structurally symmetrical with the first achromatic cemented lens and jointly undertakes the main aberration correction task.

[0057] The seventh lens element 117 is a positive power meniscus lens, and the eighth lens element 118 is a negative power meniscus lens. These two rear-mounted field lenses work together to flatten the image field and improve the edge image quality.

[0058] In this embodiment, the first lens element 111 is a high-refractive-index, low-dispersion glass. The high refractive index allows the required optical power to be achieved with a relatively gentle radius of curvature, significantly reducing spherical aberration and coma generated by the lens surface. This reduces the aberration correction pressure of subsequent lens groups from the source, while the low dispersion performance helps control the chromatic aberration introduced by the element itself. The fourth lens element 114 is a high-refractive-index, high-dispersion glass. The extremely high refractive index gives the fourth lens element 114 a strong light deflection capability, enabling it to effectively converge the light beam and strongly correct the field curvature and astigmatism introduced by the first to third lens elements 113 in the preceding group. The extremely high dispersion characteristic is designed to compensate against other low-dispersion lens elements 11 in the system, canceling the residual chromatic aberration generated by other lens elements 11, thereby achieving a fine balance of chromatic aberration across the entire field of view and the entire spectrum.

[0059] In this embodiment, the total optical length (TTL) and imaging circle diameter of the integral lens group unit 1 are 156.675 mm and 64.73 mm, respectively. It is known that the diagonal length of the sensor of a consumer-grade full-frame camera is about 43.3 mm, while the imaging circle diameter of 64.73 mm is much larger than that of a full-frame camera. Therefore, the lens of this application can perfectly cover large-area sensors and long linear array scanning sensors in high-end industrial fields. At the same time, for an 80-megapixel lens that supports a large area of ​​more than 64 mm, the total length can be controlled within 157 mm, which reflects the compact structure of the lens of this application.

[0060] In this embodiment, the effective focal length of the system is 110mm, and the ratio of the total optical length (TTL) of the integral lens unit 1 to the effective focal length (EFL) of the system (TTL / EFL) can be calculated to be 1.424, which is between 1.2 and 1.8. This reflects that the optical performance and physical size of the lens are in the best balance state, which not only ensures that there is enough physical space inside the integral lens unit (1) to accurately correct aberrations, but also avoids that the lens structure is too long, thus achieving a unity of high performance and practicality.

[0061] In this embodiment, the lens material parameters of the optical part of the lens of this application are described in the following table:

[0062]

[0063]

[0064] Specifically, R1 and R2 are the front and rear mirror surfaces of the first lens element 111, and similarly R3 and R4 are the front and rear mirror surfaces of the second lens element 112, R4 and R5 are the front and rear mirror surfaces of the third lens element 113, R6 and R7 are the front and rear mirror surfaces of the fourth lens element 114, R8 and R9 are the front and rear mirror surfaces of the fifth lens element 115, R9 and R10 are the front and rear mirror surfaces of the sixth lens element 116, R11 and R12 are the front and rear mirror surfaces of the seventh lens element 117, R13 and R14 are the front and rear mirror surfaces of the eighth lens element 118, and R15 and R16 are the front and rear mirror surfaces of the protective glass 119.

[0065] In this embodiment, Figure 9 The optical distortion curve of this lens is shown. Figure 9 As can be clearly seen, the distortion curve of this embodiment is consistently and strictly controlled within the two dashed lines of ±0.1% across the entire range from the image center (image height 0 mm) to the edge of the maximum imaging circle (approximately 32.365 mm, corresponding to a diameter of 64.73 mm). This is an exceptionally high level of distortion control.

[0066] In this embodiment, Figure 10 The modulation transfer function (MTF) curve of this lens is shown, as follows: Figure 10 As shown, at a spatial frequency as high as 70 LP / mm (a frequency sufficient to support the detail resolution requirements of an 80-megapixel sensor), the T-curve and S-curve of this lens are very close in both the center and edge fields of view, and their values ​​remain at extremely high levels, i.e., the MTF is ≥0.28 at 70 LP / mm. This indicates that: the lens of this application has extremely high resolution, meeting the stringent information requirements of an 80-megapixel sensor; the lens of this application has high contrast, high contrast ratio, clear black and white distinction, and sharp and clear images; the lens of this application has low astigmatism. Figure 10 The high degree of overlap between the T and S curves means that the lens has almost the same ability to resolve lines in different directions, and there will be no phenomenon of one direction being clear while another is blurry, thus ensuring all-around image quality.

[0067] In this embodiment, Figure 11 The relative illumination curve of this lens is shown, from... Figure 11 As can be seen, the relative illumination curve of this lens is very flat. Even at the maximum image height (the edge of the image), the relative illumination remains above 80%, which indicates that the brightness distribution within the entire imaging circle is very uniform and there are no obvious dark corners.

[0068] In this embodiment, the focus adjustment mechanism 2 includes a main lens barrel 21 and a lens mounting interface 22. The integral lens group unit 1 is fixed as a rigid whole inside the main lens barrel 21. The lens mounting interface 22 is configured to remain fixed relative to the camera body during focusing. The main lens barrel 21 and the lens mounting interface 22 are threaded together, so that by rotating the main lens barrel 21, the main lens barrel 21 together with the integral lens group unit 1 inside it can be driven to translate along the optical axis relative to the lens mounting interface 22 as a single whole to achieve focusing.

[0069] Specifically, in this embodiment, the lens mounting interface 22 includes a first interface 221, a second interface 222 and a third interface 223. All three interfaces are connected by threads. The first interface 221 is preferably a 15mm M72 interface and is responsible for cooperating with the main lens barrel 21.

[0070] In this embodiment, the focus adjustment mechanism 2 also includes a locking ring 23 and a mounting locking screw 24. The locking ring 23 is disposed between the main lens barrel 21 and the lens mounting interface 22. When focusing is completed, the mounting locking screw 24 passes through the threaded hole on the locking ring 23. By applying pressure to the mounting locking screw 24, the main lens barrel 21 is locked relative to the mounting interface to prevent focus shift.

[0071] In this embodiment, the main lens barrel 21 includes an object-side lens barrel 211, an image-side lens barrel 212, a fixing barrel 213, an aperture adjustment barrel 131, and at least one connecting screw 214. The object-side lens barrel 211 has a front end retaining ring 2111, a first lens element 111, a first spacer 121, and a first adhesive lens composed of a second lens element 112 and a third lens element 113 built into it along the optical axis. The image-side lens barrel 212 has a manual aperture assembly 132, a fourth lens element 114, a second spacer 122, and a fifth lens element 114 built into it along the optical axis. The second bonding lens, the third spacer 123, the seventh lens element 117, the fourth spacer 124, the eighth lens element 118, and the rear retaining ring 2121, together with the sixth lens element 116, form the second bonding lens. The front retaining ring 2111 is typically screwed into the front end of the object-side lens barrel 211 by means of threads. By applying an axial preload, all components are tightly pressed together. The rear retaining ring 2121 is located at the rear end of the image-side lens barrel 212 and provides a stable support reference surface for the integral lens assembly unit 1, counteracting the pressure of the front retaining ring 2111. It also serves to seal and fix, ensuring the accurate positioning of the eighth lens element 118.

[0072] Specifically, the fixing sleeve 213 is fitted onto the rear half of the object-side lens tube 211, and the connecting screw 214 passes through the fixing sleeve 213 and the object-side lens tube 211 and is screwed into the image-side lens tube 212 to fix the front lens tube assembly to the rear lens tube assembly.

[0073] In this embodiment, the integral lens unit 1 further includes an aperture structure 13, which is located in the middle of the optical system, specifically between the third lens element 113 and the fourth lens element 114. The aperture structure 13 includes an aperture adjustment cylinder 131 and a manual aperture assembly 132. The aperture adjustment cylinder 131 is located outside the image-square lens barrel 212, and the manual aperture assembly 132 is located inside the image-square lens barrel 212. The manual aperture assembly 132 has multiple blades 1321 inside, and the multiple blades 1321 are connected to protrusions 1322. The inner sidewall of the aperture adjustment cylinder 131 has grooves 1311 that fit with the protrusions 1322. By rotating the aperture adjustment cylinder 131, the protrusions 1322 can be rotated to make the multiple blades 1321 expand outward or contract inward, thereby adjusting the aperture size.

[0074] In this embodiment, the aperture structure 13 also includes a limiting pin 134 and a dimming locking screw 133. An arc-shaped annular limiting groove 2122 is machined on the outer wall of the image-square lens barrel 212. The limiting pin 134 passes through the inner wall of the aperture adjustment cylinder 131 and is engaged in this annular limiting groove 2122. The range of movement of the pin in the groove defines the maximum rotation angle of the aperture adjustment cylinder 131, that is, the complete journey from the maximum aperture to the minimum aperture. In industrial applications, the aperture value is usually fixed after adjustment. Therefore, when the aperture is adjusted to the correct position, tightening the dimming locking screw 133 will press the end of the dimming adjustment cylinder 131 against it. The friction generated will lock the cylinder relative to the image-square lens barrel 212, thus effectively preventing changes in the aperture value caused by accidental contact or equipment vibration. When it is necessary to readjust the aperture, loosen the dimming locking screw 133 to allow the dimming adjustment cylinder 131 to be in a movable state, and then rotate the dimming adjustment cylinder 131 to readjust the aperture.

[0075] The working principle of the 80-megapixel low-distortion lens provided in this application is as follows:

[0076] Optically, a modified double-Gaussian structure consisting of eight global aspherical lenses is employed. Light passes sequentially through the object-side lens tube 211, the aperture structure 13 located at the center of the system, and the image-side lens tube 212. The paired cemented lenses effectively correct chromatic aberration, while the central aperture structure 13 efficiently suppresses distortion. More importantly, this design strategically uses high-refractive-index, special dispersive glass materials to reduce and compensate for complex aberrations such as spherical aberration and coma at their source, thus achieving 80-megapixel-level high resolution and extremely low image distortion without using expensive aspherical lenses.

[0077] Mechanically, all lenses are rigidly fixed as a single, integrated lens unit 1. During focusing, by rotating the main lens barrel 21, this lens unit, as a single unit, translates linearly along the optical axis to adjust its distance from the sensor. This integrated translation focusing design greatly simplifies the structure, avoids relative movement between lens elements, ensures stable optical performance during focusing, and significantly improves the lens's vibration resistance and reliability.

[0078] This application achieves a deep coupling between optical design and mechanical structure. The optical design, through a precise combination of spherical mirrors, actively undertakes the majority of aberration correction tasks, thus freeing up the mechanical structure to employ the simplest and most reliable overall translation method. It is precisely this extremely simplified mechanical structure that allows for practical application at a controllable cost and with industrial-grade reliability, achieving a balance between optical performance, mechanical reliability, and manufacturing cost.

[0079] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An 80-megapixel low-distortion lens, characterized in that, include: An integral lens unit (1) includes at least eight lens elements (11) arranged sequentially along the optical axis, the eight lens elements (11) being, from the object side to the image side, a first lens element (111), a second lens element (112), a third lens element (113), a fourth lens element (114), a fifth lens element (115), a sixth lens element (116), a seventh lens element (117), and an eighth lens element (118); and a plurality of spacers (12) for separating the lens elements (11) from each other, and the at least eight lens elements (11) and the spacers (12) are rigidly fixed together. as well as A focus adjustment mechanism (2) includes: A main lens barrel (21), wherein the integral lens assembly unit (1) is fixed as a rigid whole within the main lens barrel (21); A lens mounting interface (22) is configured to remain fixed relative to the camera body during focusing; the main lens barrel (21) is threadedly engaged with the lens mounting interface (22) such that by rotating the main lens barrel (21), the main lens barrel (21) together with the integral lens group unit (1) inside it can be driven as a single unit to translate along the optical axis relative to the lens mounting interface (22) to achieve focusing, wherein the refractive index of the first lens element (111) is between 1.85 and 1.95, the Abbe number of the first lens element (111) is between 30 and 40, the refractive index of the eighth lens element (118) is between 1.50 and 1.55, the Abbe number of the eighth lens element (118) is greater than 63, and the plurality of lens elements (11) also satisfy at least three of the following conditions; (a) The refractive index of the second lens element (112) is between 1.72 and 1.80, and the Abbe number is between 24 and 30; (b) The refractive index of the third lens element (113) is between 1.60 and 1.65, and the Abbe number is less than 30; (c) The refractive index of the fourth lens element (114) is greater than 1.90 and the Abbe number is between 20 and 22; (d) The refractive indices of the fifth lens element (115), the sixth lens element (116) and the seventh lens element (117) are between 1.60 and 1.70, and the two Abbe numbers of the fifth lens element (115) and the seventh lens element (117) are both greater than 60.

2. The 80-megapixel low-distortion lens according to claim 1, characterized in that... The first lens element (111) is a meniscus lens with positive optical power, the second lens element (112) is a biconcave lens with negative optical power, the third lens element (113) is a biconvex lens with positive optical power, the fourth lens element (114) is a biconvex lens with positive optical power, the fifth lens element (115) is a biconcave lens with negative optical power, the sixth lens element (116) is a biconvex lens with positive optical power, the seventh lens element (117) is a meniscus lens with positive optical power, and the eighth lens element (118) is a meniscus lens with negative optical power. The image side of the integral lens unit (1) is also provided with a protective glass (119) to protect the eight lens elements (11) at the front end.

3. The 80-megapixel low-distortion lens according to claim 2, characterized in that, The first lens element (111) is a high-refractive-index, low-dispersion glass, and the fourth lens element (114) is a high-refractive-index, high-dispersion glass.

4. An 80-megapixel low-distortion lens according to claim 2, characterized in that, The second lens element (112) and the third lens element (113) constitute the first achromatic cemented lens, and the fifth lens element (115) and the sixth lens element (116) constitute the second achromatic cemented lens. The first achromatic cemented lens and the second achromatic cemented lens have the same radius of curvature, thickness, focal length, and are made of the same material.

5. An 80-megapixel low-distortion lens according to claim 1, characterized in that, The lens's optical system exhibits an absolute optical distortion of less than 0.1% across the entire field of view.

6. The 80-megapixel low-distortion lens according to claim 1, characterized in that, The ratio of the total optical length (TTL) of the integral lens unit (1) to the effective focal length (EFL) of the system, TTL / EFL, is between 1.2 and 1.

8.

7. An 80-megapixel low-distortion lens according to claim 1, characterized in that, The focus adjustment mechanism (2) further includes a locking ring (23) and a mounting locking screw (24). The locking ring (23) is disposed between the main lens barrel (21) and the lens mounting interface (22). The mounting locking screw (24) is configured to lock the main lens barrel (21) relative to the lens mounting interface (22) by applying pressure when focusing is completed.

8. An 80-megapixel low-distortion lens according to claim 1, characterized in that, The main lens tube (21) includes an object-side lens tube (211), an image-side lens tube (212), a fixing tube (213), and at least one connecting screw (214). The fixing tube (213) is sleeved on the rear half of the object-side lens tube (211). The connecting screw (214) is configured to pass through the fixing tube (213) and the object-side lens tube (211) and screw into the image-side lens tube (212) to fix the object-side lens tube (211) and the image-side lens tube (212) together.

9. An 80-megapixel low-distortion lens according to claim 1, characterized in that, The integral lens unit (1) also includes an aperture structure (13), which is disposed between the third lens element (113) and the fourth lens element (114). The aperture structure (13) includes an aperture adjustment cylinder (131) and a manual aperture group (132). The aperture adjustment cylinder (131) is disposed outside the image-square lens barrel (212), and the manual aperture group (132) is disposed inside the image-square lens barrel (212). The aperture structure (13) is configured to rotate the aperture adjustment cylinder (131) to drive the manual aperture group (132) to adjust the aperture size.

10. An 80-megapixel low-distortion lens according to claim 9, characterized in that, The aperture structure (13) further includes a dimming locking screw (133) and a limiting pin (134). The dimming locking screw (133) is configured to press or loosen the aperture adjustment cylinder (131) and the image-square lens barrel (212). The outer wall of the image-square lens barrel (212) is provided with an annular limiting groove (2122). The limiting pin (134) is configured to pass through the aperture adjustment cylinder (131) and be engaged in the annular limiting groove (2122). When the dimming locking screw (133) is in the loose state, the amount of light entering the lens is controlled when the aperture adjustment cylinder (131) is rotated for dimming.

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