Large target surface wide spectrum athermalization lens

Abstract

The application relates to a large-target-surface wide-spectrum athermalization lens, and relates to the technical field of optical design. The lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens and a tenth lens arranged in sequence along an optical axis from an object side to an image side; the second lens and the third lens, the fourth lens and the fifth lens and the sixth lens and the seventh lens are glued together; the mirror surfaces of all the lenses are standard spherical surfaces, and the centering coefficients are all greater than 0.14. The application can solve the problems of high processing cost, narrow working waveband, non-athermalization design and small target surface adaptation of the existing airborne lenses.

Description

Technical Field

[0001] This invention relates to the field of optical design technology, specifically to a large-target, wide-spectrum, athermalized lens. Background Technology

[0002] UAV-borne imaging optical systems are highly mobile and have small, hard-to-detect targets. They can achieve long-range, high-precision, and stable imaging and are widely used in military reconnaissance, fire fighting, field search and rescue, and agricultural patrol.

[0003] The corresponding optical lenses require large target areas, wide-spectrum, athermalized lenses capable of day and night target detection and operation in harsh temperature environments. However, traditional airborne optical lenses typically only cover a single band of visible or infrared light, failing to achieve all-weather detection. In harsh temperature environments, temperature changes cause lens deformation, affecting the imaging quality of the entire system. Therefore, athermalization is also a crucial lens module. However, some airborne lenses can only operate at room temperature and cannot adapt to complex temperature environments. Furthermore, these lenses are usually only compatible with smaller detector target areas, unable to maintain high image resolution over a wide field of view, making them unsuitable for long-range airborne detection. From an engineering perspective, some lenses introduce special surface shapes to correct aberrations. These special surface shapes increase the difficulty of subsequent processing and assembly, leading to higher manufacturing costs and hindering widespread adoption.

[0004] The patent application with application number CN202010358387.3 discloses a visible light near-infrared broadband apochromatic image-side telecentric lens. By effectively matching low-dispersion glass with other optical glass, the chromatic aberration of the lens is controlled within a reasonable range. However, its working wavelength is 400nm to 1000nm, which does not cover the short-wave infrared band. Moreover, this design can only work at room temperature, which does not meet the application requirements of calorimetry.

[0005] The patent application with application number CN201611116341.0 discloses a wide-angle, low-distortion, thermal-free lens covering the wavelength range of 450nm to 700nm. However, its image plane size is only 1 / 3 inch, and its narrow wavelength coverage cannot meet the requirements of large target surfaces, resulting in low detection efficiency.

[0006] Therefore, how to provide a large-target, wide-spectrum, thermal-free lens has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of the above, the purpose of this invention is to propose a large-target-area, wide-spectrum, athermalized lens that can solve the problems of high processing cost and limited widespread adoption of existing airborne lenses, narrow operating bands, lack of athermalization design, and small target surface compatibility.

[0008] To achieve the above objectives, the present invention provides a large-target, wide-spectrum, thermal-free lens, comprising: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, and a tenth lens arranged sequentially along the optical axis from the object side to the image side; the second lens and the third lens, the fourth lens and the fifth lens, and the sixth lens and the seventh lens are cemented together; the mirror surfaces of all the above lenses are standard spherical surfaces, and the centering coefficients are all greater than 0.14.

[0009] Furthermore, an aperture stop is provided between the third lens and the fourth lens.

[0010] Furthermore, the large-target, wide-spectrum, athermalized lens operates in the 400nm–1700nm band, has an entrance pupil diameter of 40mm, a full field of view of 20.6°, and a focal length of 80mm.

[0011] Furthermore, the first lens is a biconvex lens, the second lens is a biconcave lens, the third lens is a convex-concave lens, the fourth lens is a biconvex lens, the fifth lens is a biconcave lens, the sixth lens is a biconvex lens, the seventh lens is a biconcave lens, the eighth lens is a biconvex lens, the ninth lens is a biconvex lens, and the tenth lens is a biconcave lens.

[0012] Furthermore, the refractive index of the first lens is greater than 1.65, and the refractive index of the eighth lens is greater than 1.80; the Abbe numbers of the first, fifth, and ninth lenses are less than or equal to 30, and the Abbe numbers of the third and fourth lenses are both greater than 90.

[0013] Furthermore, the first lens to the tenth lens satisfy the following relationships: (T1+T10) / T5≥3; (T9+G910+T10) / (T6+T7+G89)≥1.3; (T1+T3) / (G12+G910)≥1.2; (T5+T8) / T10≤2.4;

[0014] Wherein, T1 is the center thickness of the first lens; T3 is the center thickness of the third lens; T5 is the center thickness of the fifth lens; T6 is the center thickness of the sixth lens; T7 is the center thickness of the seventh lens; T9 is the center thickness of the ninth lens; T10 is the center thickness of the tenth lens; G12 is the air gap between the first lens and the second lens; G89 is the air gap between the eighth lens and the ninth lens; and G910 is the air gap between the ninth lens and the tenth lens.

[0015] Further, the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, the focal length of the seventh lens is f7, the focal length of the eighth lens is f8, the focal length of the ninth lens is f9, the focal length of the tenth lens is f10, and the focal length of the large target area broadband athermal lens is f; satisfying the following relationship: 12 < (f1 + f2 + f3 + f4 + f5 + f6 + f7 + f8 + f9 + f10) / f < 12.4.

[0016] The beneficial effects of this invention are as follows:

[0017] This invention proposes a large-target-area, wide-spectrum, thermothermal lens, which has the following advantages:

[0018] 1. All lenses are made of standard spherical glass with a centering factor greater than 0.14, which facilitates processing and assembly.

[0019] 2. Wide operating temperature range: within the temperature range of -40℃ to +75℃, the MTF of each field of view is greater than 0.6 at 50lp / mm.

[0020] 3. The coverage band is 400nm~1700nm, spanning the visible light band, near-infrared band and short-wave infrared band, enabling all-weather high-resolution imaging in harsh environments and possessing the advantage of penetrating clouds and fog.

[0021] 4. It covers an ultra-large target surface, capable of covering a detector target surface of 20.48mm×20.48mm, effectively improving detection efficiency. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention;

[0023] Figure 2 This is the field curvature distortion diagram of the present invention in the 400nm~1700nm band;

[0024] Figure 3 The present invention provides the MTF in the 400nm~1700nm band with a cutoff frequency of 50lp / mm at 20℃, -40℃ and +75℃.

[0025] Figure 4 This is the relative illumination diagram of the present invention in the 400nm to 1700nm wavelength band.

[0026] Wherein, L1-first lens, L2-second lens, L3-third lens, L4-fourth lens, L5-fifth lens, L6-sixth lens, L7-seventh lens, L8-eighth lens, L9-ninth lens, L10-tenth lens, ST0-aperture, S1-first sphere, S2-second sphere, S3-third sphere, S4-fourth sphere, S5-fifth sphere, S6-sixth sphere, S7-seventh sphere, S8-eighth sphere, S9-ninth sphere, S10-tenth sphere, S11-eleventh sphere, S12-twelfth sphere, S13-thirteenth sphere, S14-fourteenth sphere, S15-fifteenth sphere, S16-sixteenth sphere, S17-seventeenth sphere. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 are within the scope of protection of the present invention.

[0028] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application 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 for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover 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.

[0029] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0030] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0031] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0032] To achieve the above objectives, such as Figure 1 As shown, the present invention provides a large-target, wide-spectrum, athermalized lens, comprising: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, and a tenth lens L10 arranged sequentially along the optical axis from the object side to the image side; the second lens L2 and the third lens L3, the fourth lens L4 and the fifth lens L5, and the sixth lens L6 and the seventh lens L7 are cemented together; the mirror surfaces of all the above lenses are standard spherical surfaces, and the centering coefficients are all greater than 0.14.

[0033] To further optimize the technical solution, an aperture stop ST0 is provided between the third lens and the fourth lens.

[0034] Further optimization of the technical solution resulted in a large-target, wide-spectrum, athermalized lens operating in the 400nm–1700nm band, with an entrance pupil diameter of 40mm, a full field of view of 20.6°, and a focal length of 80mm.

[0035] The technical solution is further optimized as follows: the first lens is a biconvex lens, the second lens is a biconcave lens, the third lens is a convex-concave lens, the fourth lens is a biconvex lens, the fifth lens is a biconcave lens, the sixth lens is a biconvex lens, the seventh lens is a biconcave lens, the eighth lens is a biconvex lens, the ninth lens is a biconvex lens, and the tenth lens is a biconcave lens.

[0036] Further optimization of the technical solution: the refractive index of the first lens is greater than 1.65, and the refractive index of the eighth lens is greater than 1.80; the Abbe numbers of the first, fifth, and ninth lenses are less than or equal to 30, and the Abbe numbers of the third and fourth lenses are both greater than 90. The refractive index n1 of the first lens L1 is greater than 1.65, which can reduce the lens aperture and reduce the impact of distortion; the refractive index n9 of the eighth lens L9 is greater than 1.80, which can reduce tolerance sensitivity and improve yield; the Abbe numbers vd1 of the first lens L1, vd5 of the fifth lens L5, and vd9 of the ninth lens L9 are less than or equal to 30, and anomalous dispersion materials are used to correct image chromatic aberration; the Abbe numbers vd3 and vd4 of the third lens L3 and the fourth lens L4 are greater than 90, which can improve the chromatic aberration of the lens.

[0037] Further optimizing the technical solution, the first lens to the tenth lens satisfy the following relationships: (T1+T10) / T5≥3; (T9+G910+T10) / (T6+T7+G89)≥1.3; (T1+T3) / (G12+G910)≥1.2; (T5+T8) / T10≤2.4;

[0038] Wherein, T1 is the center thickness of the first lens; T3 is the center thickness of the third lens; T5 is the center thickness of the fifth lens; T6 is the center thickness of the sixth lens; T7 is the center thickness of the seventh lens; T9 is the center thickness of the ninth lens; T10 is the center thickness of the tenth lens; G12 is the air gap between the first lens and the second lens; G89 is the air gap between the eighth lens and the ninth lens; and G910 is the air gap between the ninth lens and the tenth lens.

[0039] Further optimizing the technical solution, the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, the focal length of the seventh lens is f7, the focal length of the eighth lens is f8, the focal length of the ninth lens is f9, the focal length of the tenth lens is f10, and the focal length of the large target area broadband athermal lens is f; satisfying the following relationship: 12 < (f1 + f2 + f3 + f4 + f5 + f6 + f7 + f8 + f9 + f10) / f < 12.4.

[0040] The optical system composed of the above lenses achieves the following optical specifications: (1) focal length equal to 80mm; (2) entrance pupil diameter of 40mm; (3) spectral range of 0.4um to 1.7um; (4) full field of view of 20.6°; (5) distortion less than 1.5%, such as Figure 2As shown; (6) The relative illuminance across the entire field of view is greater than 0.9, as shown Figure 4 As shown; (7) Within a temperature range of -40℃ to 75℃, the imaging quality is good, and MTF@50lp / mm>0.6, as shown. Figure 3 (a) Figure 3 (b) and 3(c) show the MTF at room temperature, -40°C and +75°C respectively; (8) the total length of the lens is less than 130mm.

[0041] Figure 2 This is a field curvature distortion curve of the fixed-focus lens of the present invention. In the coordinate system on the left, the horizontal axis represents the magnitude of the field curvature in mm; the vertical axis represents the normalized image height, which has no unit; (wherein, the maximum field of view is 10.3°, the sagittal field curvature = 0.0816mm, and the meridional field curvature = 0.0363mm); in the coordinate system on the right, the horizontal axis represents the magnitude of the distortion in %; the vertical axis represents the normalized image height, which has no unit (wherein, the maximum field of view is 10.3°, and the maximum distortion = 1.4651%).

[0042] In Table 1, the radius of curvature represents the curvature of the lens surface. A positive value indicates that the surface bends towards the image plane, and a negative value indicates that the surface bends towards the object plane. "Infinity" indicates that the surface is flat and the radius of curvature is infinite. The thickness represents the central axial distance between the current surface and the next surface. The refractive index represents the ability of the material between the current surface and the next surface to deflect light. The blank space indicates that the current position is air and the refractive index is 1.

[0043]

[0044]

[0045] Table 1

[0046] This invention proposes a large-target-area, wide-spectrum, thermal-free lens with the following advantages: all lenses are made of standard spherical glass with a centering coefficient greater than 0.14, facilitating processing and assembly; it has a wide operating temperature range, with an MTF greater than 0.6 at 50 lp / mm for each field of view within the temperature range of -40℃ to +75℃; it covers a wavelength range of 400nm to 1700nm, spanning the visible, near-infrared, and short-wave infrared bands, enabling all-weather, high-resolution imaging in harsh environments and possessing the advantage of penetrating clouds and fog; and it covers an ultra-large target area, capable of covering a detector target area of ​​20.48mm × 20.48mm, effectively improving detection efficiency.

[0047] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A large-target, wide-spectrum, thermochromic lens, characterized in that, include: The first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens, and tenth lens are arranged sequentially from the object side to the image side along the optical axis; the second lens and the third lens, the fourth lens and the fifth lens, and the sixth lens and the seventh lens are cemented together; the mirror surfaces of all the above lenses are standard spherical surfaces, and the centering coefficients are all greater than 0.14; The first lens is a biconvex lens, the second lens is a biconcave lens, the third lens is a convex-concave lens, the fourth lens is a biconvex lens, the fifth lens is a biconcave lens, the sixth lens is a biconvex lens, the seventh lens is a biconcave lens, the eighth lens is a biconvex lens, the ninth lens is a biconvex lens, and the tenth lens is a biconcave lens. The first lens to the tenth lens satisfy the following relationships: (T1+T10) / T5≥3; (T9+G910+T10) / (T6+T7+G89)≥1.3; (T1+T3) / (G12+G910)≥1.2; (T5+T8) / T10≤2.4; Wherein, T1 is the center thickness of the first lens; T3 is the center thickness of the third lens; T5 is the center thickness of the fifth lens; T6 is the center thickness of the sixth lens; T7 is the center thickness of the seventh lens; T9 is the center thickness of the ninth lens; T10 is the center thickness of the tenth lens; G12 is the air gap between the first lens and the second lens; G89 is the air gap between the eighth lens and the ninth lens; G910 is the air gap between the ninth lens and the tenth lens; The focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, the focal length of the seventh lens is f7, the focal length of the eighth lens is f8, the focal length of the ninth lens is f9, the focal length of the tenth lens is f10, and the focal length of the large target area broadband athermal lens is f; satisfying the following relationship: 12 < (f1 + f2 + f3 + f4 + f5 + f6 + f7 + f8 + f9 + f10) / f < 12.

4.

2. The large-target, wide-spectrum, thermochromic lens as described in claim 1, characterized in that, An aperture stop is provided between the third lens and the fourth lens.

3. A large-target, wide-spectrum, thermochromic lens as described in claim 1 or 2, characterized in that, The large-area, wide-spectrum, thermochromic lens operates in the 400nm~1700nm band, has an entrance pupil diameter of 40mm, a full field of view of 20.6°, and a focal length of 80mm.

4. The large-target-area, wide-spectrum, thermochromic lens as described in claim 1, characterized in that, The first lens has a refractive index greater than 1.65, and the eighth lens has a refractive index greater than 1.80; the Abbe numbers of the first, fifth, and ninth lenses are less than or equal to 30, and the Abbe numbers of the third and fourth lenses are both greater than 90.

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