Large-target-surface wide-spectrum athermalization lens

Abstract

The invention relates to a large-target-surface wide-spectrum athermalization lens, and relates to the technical field of optical design. 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 which are sequentially arranged from an object space to an image space along an 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 glued together. The mirror surfaces of all the lenses are standard spherical surfaces, and the centering coefficients are all larger than 0.14. The problems that an existing airborne lens is high in machining cost, not easy to popularize, narrow in working wave band, not subjected to athermalization design, small in adaptive target surface and the like can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of optical design, in particular to a large-target-surface wide-spectrum athermal lens. Background Art

[0002] The drone's onboard imaging optical system is highly maneuverable, and the target is small and not easy to be discovered. It can achieve long-distance, high-precision and stable imaging, and is widely used in military detection, fire fighting, field search and rescue, agricultural patrol and other fields.

[0003] The matching optical lens is required to be a large target surface, wide spectrum athermal lens, which can detect targets day and night and work in harsh temperature environments. However, traditional airborne optical lenses usually only cover a single band of visible light or infrared light and cannot achieve all-weather detection. In harsh temperature environments, temperature changes will cause the lens to deform and affect the imaging quality of the entire system, so athermal design is also an important module of the lens, but some airborne lenses can only work at room temperature and cannot adapt to complex temperature environments. In addition, these lenses are usually only suitable for smaller detector target surfaces and cannot maintain high image resolution within a large field of view. They are not suitable as long-distance airborne detection lenses; from an engineering perspective, some lenses introduce special surface shapes to correct aberrations. These special surface shapes increase the difficulty of subsequent processing and adjustment, which increases the processing cost and is not conducive to large-scale promotion.

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

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

[0006] Therefore, how to provide a large target surface and wide spectrum athermal lens has become a technical problem that technical personnel in this field need to solve urgently. Summary of the invention

[0007] In view of the above situation, the purpose of the present invention is to propose a large target surface and wide spectrum athermal lens, which can solve the problems of existing airborne lenses such as high processing cost and low popularization, narrow working band, lack of athermal design and small adaptation target surface.

[0008] To achieve the above-mentioned object, the present invention provides a large target surface wide spectrum athermal 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 in sequence 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 glued 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, a stop is provided between the third lens and the fourth lens.

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

[0011] Further, 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 lens, the fifth lens and the ninth lens are less than or equal to 30, and the Abbe numbers of the third lens and the fourth lens are both greater than 90.

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

[0014] Among them, 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.

[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 surface wide spectrum athermalization lens is f; the following relationship is satisfied: 12<(f1+f2+f3+f4+f5+f6+f7+f8+f9+f10) / f<12.4.

[0016] The beneficial effects of the present invention are:

[0017] The present invention proposes a large-target-surface wide-spectrum athermal lens, which has the following advantages:

[0018] 1. All lenses are made of standard spherical glass lenses with a centering coefficient greater than 0.14, which is easy to process and adjust.

[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, covering the visible light band, near-infrared band and short-wave infrared band. It can achieve all-weather high-resolution imaging in harsh environments and has the advantage of penetrating clouds and fog.

[0021] 4. Covering a large target surface, it can cover the detector target surface of 20.48mm×20.48mm, effectively improving the detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the present invention;

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

[0024] Figure 3 It is the MTF of the present invention at 20°C, -40°C and +75°C in the 400nm to 1700nm band and at a cutoff frequency of 50lp / mm;

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

[0026] Among them, 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 spherical surface, S2-second spherical surface, S3-third spherical surface, S4-fourth spherical surface, S5-fifth spherical surface, S6-sixth spherical surface, S7-seventh spherical surface, S8-eighth spherical surface, S9-ninth spherical surface, S10-tenth spherical surface, S11-eleventh spherical surface, S12-twelfth spherical surface, S13-thirteenth spherical surface, S14-fourteenth spherical surface, S15-fifteenth spherical surface, S16-sixteenth spherical surface, S17-seventeenth spherical surface. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0029] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0030] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0031] In addition, the terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] To achieve the above purpose, Figure 1 As shown, the present invention provides a large target surface wide spectrum athermal 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 in sequence from the object side to the image side along the optical axis; 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 glued 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, a stop ST0 is provided between the third lens and the fourth lens.

[0034] To further optimize the technical solution, the large target wide spectrum athermal lens operates in the 400nm to 1700nm band, has an entrance pupil diameter of 40mm, a full field of view of 20.6°, and a focal length of 80mm.

[0035] To further optimize the technical solution, 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] To further optimize 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 lens, the fifth lens, and the ninth lens are less than or equal to 30, and the Abbe numbers of the third lens and the fourth lens are both greater than 90. The refractive index n1 of the first lens L1 is greater than 1.65, so that the lens aperture can be reduced and the influence of distortion can be reduced; the refractive index n9 of the eighth lens L9 is greater than 1.80, so that the tolerance sensitivity can be reduced and the yield rate can be improved; the Abbe number vd1 of the first lens L1, the Abbe number vd5 of the fifth lens L5, and the Abbe number 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, so that the dispersion of the lens can be improved.

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

[0038] Among them, 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.

[0039] To further optimize 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 surface wide spectrum athermal lens is f; the following relationship is satisfied: 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 indicators: (1) focal length equal to 80 mm; (2) entrance pupil diameter is 40 mm; (3) spectral range is 0.4 μm to 1.7 μm; (4) full field of view angle is 20.6°; (5) distortion is less than 1.5%, such as Figure 2As shown; (6) The relative illumination of the entire field of view is greater than 0.9, such as Figure 4 (7) In the temperature range of -40℃ to 75℃, the imaging quality is good, MTF@50lp / mm>0.6, as shown in Figure 3 (a) Figure 3 (b) and 3(c), which represent the MTF at room temperature, -40℃ and +75℃ respectively; (8) The total length of the lens is less than 130mm.

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

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

[0043]

[0044]

[0045] Table 1

[0046] The present invention proposes a large-target-area, wide-spectrum athermal lens having the following advantages: all lenses are made of standard spherical glass lenses, and the centering coefficients are all greater than 0.14, which are convenient for processing and adjustment; the operating temperature range is wide, and within the temperature range of -40°C to +75°C, the MTF of each field of view is greater than 0.6 at 50lp / mm; the covered band is 400nm to 1700nm, and the covered band spans the visible light band, the near-infrared band and the short-wave infrared band, which can achieve all-weather high-resolution imaging in harsh environments, and has the advantage of penetrating clouds and fog; it covers an ultra-large target surface, which can cover a detector target surface of 20.48mm×20.48mm, and effectively improves the detection efficiency.

[0047] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A large target surface and wide spectrum athermal lens, characterized in that: include: 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 are arranged in sequence 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 glued together; the mirror surfaces of all the above lenses are standard spherical surfaces, and the centering coefficients are all greater than 0.

14.

2. The large target surface and wide spectrum athermal lens according to claim 1, characterized in that: A stop is arranged between the third lens and the fourth lens.

3. The large target surface wide spectrum athermal lens according to claim 1 or 2, characterized in that: The large-target wide-spectrum athermal lens operates in the 400nm to 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 surface and wide spectrum athermal lens according to claim 1, characterized in that: 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.

5. The large target surface wide spectrum athermal lens according to claim 1 or 4, characterized in that: 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 lens, the fifth lens and the ninth lens are less than or equal to 30, and the Abbe numbers of the third lens and the fourth lens are both greater than 90.

6. The large target surface and wide spectrum athermal lens as claimed in claim 5, characterized in that: The first lens to the tenth lens satisfy the following relationship: (T1+T10) / T5≥3; (T9+G910+T10) / (T6+T7+G89)≥1.3; (T1+T3) / (G12+G910)≥1.2; (T5+T8) / T10≤2.4; Among them, 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.

7. The large-target-area wide-spectrum athermal lens according to claim 6, characterized in that: 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 surface wide spectrum athermalization lens is f; the following relationship is satisfied: 12<(f1+f2+f3+f4+f5+f6+f7+f8+f9+f10) / f<12.4.

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