High-performance airborne head-mounted low-light night vision optical system

Abstract

The invention relates to the technical field of optical design, in particular to a high-performance airborne head-mounted low-light night vision optical system which sequentially comprises a first positive lens, a first gluing assembly, a fourth positive lens, a fifth positive lens, a second gluing assembly and an eighth negative lens from an object side to an imaging surface along an optical axis. The image side surface is a concave surface; the first gluing assembly has a concave object-side surface and a concave image-side surface. The fourth positive lens has positive focal power, the object side surface of the fourth positive lens is a convex surface, and the image side surface is a convex surface; the fifth positive lens has positive focal power, the object side surface of the fifth positive lens is a convex surface, and the image side surface is a convex surface; the second gluing assembly has a concave object-side surface and a convex image-side surface; the eighth negative lens has negative focal power, the object side surface of the eighth negative lens is a concave surface, and the image side surface is a convex surface. The optical system has the advantages of large relative aperture, low cost, good image quality, small size, light weight and good thermal stability, and can work normally at low temperature and high temperature.

Description

Technical Field

[0001] The invention relates to the technical field of optical design, and in particular to a high-performance airborne head-mounted low-light-level night vision optical system. Background Art

[0002] When pilots are flying an aircraft, they need to frequently take videos and photos to identify objects in the air and on the ground, especially in poor lighting conditions. The low-light night vision optical system can clearly capture videos and photos of the surrounding environment. These data allow pilots to accurately obtain information about the surrounding environment and quickly make driving decisions, thus avoiding accidents caused by inaccurate photography.

[0003] The wavelength of visible light for human eyes is 380nm~780nm, and the light in this band is relatively weak at night, resulting in poor visual effect of objects for human eyes at night. Therefore, it is necessary to use sensors that sense wider bands to assist in the work. The wavelength of the near-infrared band is 780nm~1100nm. In order to improve the imaging quality and increase the illumination of the image plane, it is necessary to select a low-light sensor with a working band of 400nm~1100nm to cooperate with the optical system. In order to increase the amount of light entering, the relative aperture of the optical system is required to be large enough, and the corresponding F number value should be small enough.

[0004] The pilot's working environment is quite special. There are many lighting and display devices in the aircraft cabin. In order to avoid interference from the lighting devices in the cabin to the greatest extent, the working wavelength of the optical system should meet the requirements of the corresponding standards, usually 600nm to 1000nm. In order to ensure that the pilot can observe objects near and far and avoid manual focusing, the imaging depth of field of the optical system is generally required to meet 2m to near infinity.

[0005] Using general optical lenses as airborne lenses, without targeted design for low-light environments, will result in a significant lack of brightness and poor image clarity in low-light environments with poor illumination. In addition, general optical lenses are large in size and heavy in weight. It is inconvenient to install them on pilot helmets, which are already sensitive to weight. Airborne lenses also need to be resistant to high and low temperatures, so there are great requirements for the selection of lens materials, and materials with relatively stable expansion coefficients need to be selected.

[0006] Patent application number 202311104000.1 discloses a large-image-area low-light-level night vision lens, which uses a design combining four glass lenses and four plastic aspherical lenses to achieve better image quality. However, the processing cost of aspherical lenses is relatively high, and the installation precision requirements are relatively high, and the thermal stability of plastic lenses is poor.

[0007] Patent application number 202311105269.1 discloses a low-light-level night vision lens with a large field of view and large relative aperture, which uses ten all-glass lenses to achieve an F number of 1.4 and a full field of view of 67°. However, the total length reaches 111.5mm, and the structure is not compact enough, making the optical system expensive and not small and light enough.

[0008] The existing patented lenses use a glass-plastic hybrid lens. The use of plastic lenses will make the thermal stability of the lens worse, and the use of aspherical lenses will lead to high processing costs and high installation precision requirements. Lenses with large relative apertures have the characteristics of lengthy structures, a large number of lenses, and are not light and compact enough. Summary of the invention

[0009] The present invention provides a high-performance airborne head-mounted low-light-level night vision optical system to solve the technical problems mentioned in the background technology.

[0010] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0011] The present invention provides a high-performance airborne head-mounted low-light-level night vision optical system, which includes the following components in order from the object side to the imaging surface along the optical axis:

[0012] a first positive lens having positive power, wherein the object side surface of the first positive lens is a convex surface, and the image side surface of the first positive lens is a concave surface;

[0013] A first glued component with negative optical power, wherein the object side of the first glued component is a concave surface, and the image side of the first glued component is a concave surface;

[0014] a fourth positive lens having positive power, wherein the object side surface of the fourth positive lens is convex, and the image side surface of the fourth positive lens is convex;

[0015] a fifth positive lens having positive power, wherein the object side surface of the fifth positive lens is convex, and the image side surface of the fifth positive lens is convex;

[0016] Two glued components with negative optical power, the object side of the second glued component is concave, and the image side of the second glued component is convex;

[0017] The eighth negative lens has negative power, the object side surface of the eighth negative lens is a concave surface, and the image side surface of the eighth negative lens is a convex surface.

[0018] Furthermore, the first bonding component comprises:

[0019] a second negative lens having negative optical power, wherein the object side surface of the second negative lens is a concave surface, and the image side surface of the second negative lens is a convex surface;

[0020] The third negative lens has negative optical power, the object side surface of the third negative lens is conformed to the image side surface of the second negative lens and is bonded by glue, and the image side surface of the third negative lens is a concave surface.

[0021] Furthermore, the thickness of the second negative lens is 0.998 mm; the optical power of the second negative lens is -0.012; the refractive index of the second negative lens is 1.66, and the Abbe number is between 57.34 and 57.35; the minimum air spacing between the first positive lens and the second negative lens on the optical axis is 1.044 mm;

[0022] The thickness of the third negative lens is 1.047 mm, the optical power of the third negative lens is -0.08, the refractive index of the third negative lens is 1.96, and the Abbe number is 17.47; the minimum air distance between the third negative lens and the fourth positive lens on the optical axis is 2.392 mm.

[0023] Furthermore, the second gluing component comprises:

[0024] a sixth positive lens having negative optical power, wherein the object side surface of the sixth positive lens is a concave surface, and the image side surface of the sixth positive lens is a convex surface;

[0025] The seventh negative lens has positive power, the object side surface of the seventh negative lens is conformed to the image side surface of the sixth positive lens and is bonded by glue, and the image side surface of the seventh negative lens is a convex surface.

[0026] Furthermore, the thickness of the sixth positive lens is 3.656 mm, the optical power of the sixth positive lens is 0.077, the refractive index of the sixth positive lens is 1.67, and the Abbe number is 51.74;

[0027] The thickness of the seventh negative lens is 3.134 mm, the optical power of the seventh negative lens is -0.081, the refractive index of the seventh negative lens is 1.96, and the Abbe number is 17.47. The minimum air distance between the seventh negative lens and the eighth negative lens on the optical axis is 4.689 mm.

[0028] Furthermore, the surfaces of the first positive lens object side, the first positive lens image side, the second negative lens object side, the third negative lens image side, the fourth positive lens object side, the fourth positive lens image side, the fifth positive lens object side, the fifth positive lens image side, the sixth positive lens object side, the seventh negative lens image side, the eighth negative lens object side and the eighth negative lens image side are all coated with an anti-reflection and anti-transmission film, and its reflectivity is not more than 0.5% when the wavelength is between 600nm and 1000nm.

[0029] Furthermore, it also includes filters and imaging surfaces arranged in sequence along the optical axis from the object side to the imaging surface;

[0030] The filter is arranged on the image side of the eighth negative lens, and the thickness of the filter is 0.5 mm; the minimum air distance between the filter and the eighth negative lens on the optical axis is 0.1 mm; the minimum air distance between the filter and the imaging surface on the optical axis is 0.5 mm.

[0031] Furthermore, the optical power of the first positive lens is 0.049; the thickness of the first positive lens is 2.132 mm; the refractive index of the first positive lens is 2.05, and the Abbe number is 26.99;

[0032] The optical power of the fourth positive lens is 0.075; the thickness of the fourth positive lens is 2.569 mm; the refractive index of the fourth positive lens is 1.88, and the Abbe number is 40.16;

[0033] The optical power of the fifth positive lens is 0.053; the thickness of the fifth positive lens is 3.818 mm; the minimum air distance between the fourth positive lens and the fifth positive lens on the optical axis is 1.689 mm; the refractive index of the fifth positive lens is 2.05, and the Abbe number is 26.99;

[0034] The optical power of the eighth negative lens is -0.064, the thickness of the eighth negative lens is 1.140 mm, the refractive index of the eighth negative lens is 1.69, and the Abbe number is 53.38.

[0035] Furthermore, the effective focal length f1 of the first positive lens and the effective focal length f of the optical system satisfy:

[0036] 1<f1 / f<1.5;

[0037] And / or, the optical system satisfies the following conditions:

[0038] -2.5<(R11+R12) / (R11-R12)<-1;

[0039] Wherein, R11 represents the radius of curvature of the object side of the first lens, and R12 represents the radius of curvature of the image side of the first lens; and / or, the effective focal length f of the optical system, the arc θ of the maximum half field angle, and the real image height IH corresponding to the maximum field angle satisfy:

[0040] 0.45<(IH / 2) / (f×θ)<0.65.

[0041] Furthermore, the distortion of the full field of view of the optical system is less than 1.5%; the horizontal field of view angle of the optical system is not less than 40°, and the vertical field of view angle is not less than 30°.

[0042] Beneficial effects of the present invention:

[0043] 1. The high-performance airborne head-mounted low-light night vision optical system provided by the present invention is composed of eight lenses and a filter, all of which are ordinary spherical lenses, and the materials are all domestic Chengdu Guangming materials, which are low in cost. And the materials used are all low-expansion coefficient glass, which has a good effect of resisting high and low temperatures.

[0044] 2. The high-performance airborne head-mounted low-light night vision optical system provided by the present invention has an optical size of only φ16×30mm under the premise that the F number reaches 1.4. The present invention is miniaturized and lightweight while still ensuring the amount of light entering.

[0045] 3. The high-performance airborne head-mounted low-light-level night vision optical system provided by the present invention supports the low-light-level band of 600nm to 1100nm, ensuring clear imaging in low-light environments. The maximum field of view distortion is less than 1.5%, ensuring that the degree of deformation of the center and edge of the field of view is small enough. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a structural schematic diagram of the present invention;

[0047] Figure 2 It is the optical path trend diagram of the present invention;

[0048] Figure 3 A spot diagram of the high-performance airborne head-mounted low-light-level night vision optical system provided by the present invention;

[0049] Figure 4 The optical modulation transfer function MTF curve diagram of the high-performance airborne head-mounted low-light-level night vision optical system provided by the present invention at room temperature of 20°C;

[0050] Figure 5 The point diagram and optical modulation transfer function MTF curve diagram of the high-performance airborne head-mounted low-light-level night vision optical system provided by the present invention at a high temperature of 70°C;

[0051] Figure 6 The point diagram and optical modulation transfer function MTF curve diagram of the high-performance airborne head-mounted low-light night vision optical system provided by the present invention at a low temperature of -55°C;

[0052] Figure 7 is the distortion-field of view diagram of the present invention;

[0053] Figure 8 The optical modulation transfer function MTF curve of the present invention at a working distance of 2 meters.

[0054] Description of reference numerals:

[0055] 1. First positive lens; 2. Second negative lens; 3. Third negative lens; 4. Fourth positive lens; 5. Fifth positive lens; 6. Sixth positive lens; 7. Seventh negative lens; 8. Eighth negative lens; 9. Filter; 10. Imaging surface;

[0056] S1, object side surface of the first positive lens; S2, image side surface of the first positive lens; S3, object side surface of the second negative lens; S4, image side surface of the second negative lens; S5, image side surface of the third negative lens; S6, object side surface of the fourth positive lens; S7, image side surface of the fourth positive lens; S8, object side surface of the fifth positive lens; S9, image side surface of the fifth positive lens; S10, object side surface of the sixth positive lens; S11, image side surface of the sixth positive lens; S12, image side surface of the seventh negative lens; S13, object side surface of the eighth negative lens; S14, image side surface of the eighth negative lens; S15, object side surface of the filter; S16, object side surface of the filter. DETAILED DESCRIPTION

[0057] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Preferred embodiments of the present invention are provided in the drawings. However, the present invention can be implemented in many other different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0058] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0059] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0060] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0061] It should also be noted that, in the embodiments of the present application, the same figure mark is used to represent the same component or the same part. For the same parts in the embodiments of the present application, the figure may only mark one of the parts or components as an example. It should be understood that the figure mark also applies to other identical parts or components.

[0062] Reference Figure 1 and Figure 2 The embodiment of the present application provides a high-performance airborne head-mounted low-light-level night vision optical system, which includes the following components in sequence from the object side to the imaging surface along the optical axis:

[0063] A first positive lens 1 having positive refractive power, wherein the object side surface S1 of the first positive lens is a convex surface, and the image side surface S2 of the first positive lens is a concave surface;

[0064] A first glued component with negative optical power, wherein the object side of the first glued component is a concave surface, and the image side of the first glued component is a concave surface;

[0065] a fourth positive lens 4 having positive power, wherein the object side surface S6 of the fourth positive lens is a convex surface, and the image side surface S7 of the fourth positive lens is a convex surface;

[0066] A fifth positive lens 5 having positive power, wherein the object side surface S8 of the fifth positive lens is a convex surface, and the image side surface S9 of the fifth positive lens is a convex surface;

[0067] A second glued component with negative optical power, a second glued component, an object side of the second glued component is a concave surface, and an image side of the second glued component is a convex surface;

[0068] The eighth negative lens 8 has negative power, the object-side surface S13 of the eighth negative lens is a concave surface, and the image-side surface S14 of the eighth negative lens is a convex surface.

[0069] All the aforementioned lenses achieve good chromatic aberration and aberration correction effects through material matching, and the aperture is located on the surface of the object side S6 of the fourth positive lens.

[0070] In some embodiments, the first adhesive component includes:

[0071] A second negative lens 2 having negative optical power, wherein the object side surface S3 of the second negative lens is a concave surface, and the image side surface S4 of the second negative lens is a convex surface;

[0072] The third negative lens 3 has negative optical power, the object side surface of the third negative lens is conformed to the image side surface S4 of the second negative lens and is bonded by glue, and the image side surface S5 of the third negative lens is a concave surface.

[0073] In some embodiments, the thickness of the second negative lens 2 is 0.998 mm; the optical power of the second negative lens 2 is -0.012; the refractive index of the second negative lens 2 is 1.66, and the Abbe number is between 57.34 and 57.35; the minimum air spacing between the first positive lens 1 and the second negative lens 2 on the optical axis is 1.044 mm;

[0074] The thickness of the third negative lens 3 is 1.047 mm, and the optical focal length of the third negative lens 3 is -0.08; the refractive index of the third negative lens 3 is 1.96, and the Abbe number is 17.47; the minimum air distance between the third negative lens 3 and the fourth positive lens 4 on the optical axis is 2.392 mm.

[0075] In some embodiments, the second adhesive component comprises:

[0076] A sixth positive lens 6 having negative optical power, wherein the object side surface S10 of the sixth positive lens is a concave surface, and the image side surface S11 of the sixth positive lens is a convex surface;

[0077] The seventh negative lens 7 has positive power, the object side surface of the seventh negative lens is conformed to the image side surface S11 of the sixth positive lens and is bonded by glue, and the image side surface S12 of the seventh negative lens is convex.

[0078] In some embodiments, the thickness of the sixth positive lens 6 is 3.656 mm, the optical power of the sixth positive lens 6 is 0.077, the refractive index of the sixth positive lens 6 is 1.67, and the Abbe number is 51.74.

[0079] The thickness of the seventh negative lens 7 is 3.134 mm, the optical power of the seventh negative lens 7 is -0.081, the refractive index of the seventh negative lens 7 is 1.96, and the Abbe number is 17.47. The minimum air distance between the seventh negative lens 7 and the eighth negative lens 8 on the optical axis is 4.689 mm.

[0080] In some embodiments, the surfaces of the first positive lens object side S1, the first positive lens image side S2, the second negative lens object side S3, the third negative lens image side S5, the fourth positive lens object side S6, the fourth positive lens image side S7, the fifth positive lens object side S8, the fifth positive lens image side S9, the sixth positive lens object side S10, the seventh negative lens image side S12, the eighth negative lens object side S13 and the eighth negative lens image side S14 are all coated with an anti-reflection and anti-reflection film, and the reflectivity thereof is not greater than 0.5% at a wavelength between 600nm and 1000nm.

[0081] In some embodiments, it also includes a filter 9 and an imaging surface 10 arranged in sequence along the optical axis from the object side to the imaging surface;

[0082] The filter 9 is arranged on the side of the image side S14 of the eighth negative lens, and the thickness of the filter 9 is 0.5 mm; the minimum air distance between the filter 9 and the eighth negative lens 8 on the optical axis is 0.1 mm; the minimum air distance between the filter 9 and the imaging surface 10 on the optical axis is 0.5 mm. The object side S15 and the object side S16 of the filter are both planes, and the filter 9 is a piece of flat glass without optical power.

[0083] In some embodiments, the optical power of the first positive lens 1 is 0.049; the thickness of the first positive lens 1 is 2.132 mm; the refractive index of the first positive lens 1 is 2.05, and the Abbe number is 26.99.

[0084] The optical power of the fourth positive lens 4 is 0.075; the thickness of the fourth positive lens 4 is 2.569 mm; the refractive index of the fourth positive lens 4 is 1.88, and the Abbe number is 40.16.

[0085] The optical focal length of the fifth positive lens 5 is 0.053; the thickness of the fifth positive lens 5 is 3.818 mm; the minimum air distance between the fourth positive lens 4 and the fifth positive lens 5 on the optical axis is 1.689 mm; the refractive index of the fifth positive lens 5 is 2.05, and the Abbe number is 26.99.

[0086] The optical power of the eighth negative lens 8 is -0.064, the thickness of the eighth negative lens 8 is 1.140 mm, the refractive index of the eighth negative lens 8 is 1.69, and the Abbe number is 53.38.

[0087] In some embodiments, the distortion of the full field of view of the optical system is less than 1.5%; the horizontal field of view angle of the optical system is not less than 40°, and the vertical field of view angle is not less than 30°.

[0088] In some embodiments, the effective focal length f1 of the first positive lens 1 and the effective focal length f of the optical system satisfy:

[0089] 1<f1 / f<1.5;

[0090] By limiting the effective focal length, refractive index and curvature radius of the first positive lens 1, the deflection of large-angle light by the first lens 1 is controlled, which improves the brightness of the optical system and facilitates the subsequent lens group to correct the aberration of the optical system.

[0091] In some embodiments, the effective focal length f2 of the first glued component and the effective focal length f of the optical system satisfy:

[0092] 0.5<|f2 / f|<1;

[0093] By limiting the effective focal length of the first glued component and matching the refractive index of the front and rear glasses, it is helpful to reduce aberrations such as spherical aberration, chromatic aberration, and distortion of the entire optical system, thereby improving the imaging quality of the optical system.

[0094] In some embodiments, the effective focal length f4 of the fourth positive lens 4 and the effective focal length f of the optical system satisfy:

[0095] 0.6<f4 / f<1.2;

[0096] By limiting the effective focal length of the fourth positive lens 4 , it is beneficial to reduce the overall aberration of the optical system and improve the imaging quality of the optical system.

[0097] In some embodiments, the effective focal length f5 of the fifth positive lens 5 and the effective focal length f of the optical system satisfy:

[0098] 0.8<f5 / f<1.6;

[0099] By limiting the effective focal length of the fifth positive lens 5 , it is helpful to reduce the overall aberration of the optical system and improve the imaging quality of the optical system.

[0100] In some embodiments, the effective focal length f6 of the second glued assembly satisfies the effective focal length f of the optical system:

[0101] 3.5<|f6 / f|<7.5;

[0102] By limiting the effective focal length of the second glued component and combining the positive and negative optical power matching of the front and rear lens glasses, the aperture is located between the first glued component and the second glued component, and forms a symmetrical deformed double Gaussian form with the first glued component of the front group, which is beneficial to reducing the chromatic aberration and spherical aberration of the optical system and improving the imaging quality of the optical system.

[0103] In some embodiments, the effective focal length f8 of the eighth negative lens 8 and the effective focal length f of the optical system satisfy:

[0104] 0.7<|f8 / f|<1.2;

[0105] By limiting the focal length of the eighth negative lens 8 and the effective focal length of the optical system and using a lens with negative optical power, the light of the optical system can be effectively deflected to the corresponding image plane height.

[0106] In some embodiments, the optical system satisfies the following conditional formula:

[0107] -2.5<(R11+R12) / (R11-R12)<-1;

[0108] Wherein, R11 represents the curvature radius of the object side surface S1 of the first positive lens, and R12 represents the curvature radius of the image side surface S2 of the first positive lens.

[0109] By limiting the curvature radius of the first positive lens 1 within a reasonable range, the machinability of the first positive lens 1 can be effectively guaranteed, the grinding yield of the first positive lens 1 can be increased, the processing cost can be reduced, and the aberration of the optical system can be reduced to improve the performance quality.

[0110] In some embodiments, the optical system satisfies the following conditional formula:

[0111] -1.2<(R41+R42) / (R41-R42)<-0.2;

[0112] Wherein, R41 represents the curvature radius of the object-side surface S6 of the fourth positive lens, and R42 represents the curvature radius of the image-side surface S7 of the fourth positive lens.

[0113] By limiting the curvature radius of the fourth positive lens 4 within a reasonable range, the machinability of the fourth positive lens 4 can be effectively guaranteed, the grinding yield of the fourth positive lens 4 can be increased, the processing cost can be reduced, and the aberration of the airborne optical system can be reduced to improve the performance quality.

[0114] In some embodiments, the optical system satisfies the following conditional formula:

[0115] -0.5<(R51+R52) / (R51-R52)<-0.1;

[0116] Wherein, R51 represents the curvature radius of the object-side surface S8 of the fifth positive lens, and R52 represents the curvature radius of the image-side surface S9 of the fifth positive lens.

[0117] By limiting the curvature radius of the fifth positive lens 5 within a reasonable range, the machinability of the fifth positive lens 5 can be effectively guaranteed, the grinding yield of the fifth positive lens 5 can be increased, the processing cost can be reduced, and the aberration of the optical system can be reduced to improve the performance quality.

[0118] In some embodiments, the optical system satisfies the following conditional formula:

[0119] -2.2<(R81+R82) / (R81-R82)<-0.8;

[0120] Wherein, R81 represents the curvature radius of the object-side surface S13 of the eighth negative lens, and R82 represents the curvature radius of the image-side surface S14 of the eighth negative lens.

[0121] By limiting the radius of curvature of the eighth negative lens 8 within a reasonable range, the machinability of the eighth negative lens 8 can be effectively guaranteed, the grinding yield of the eighth negative lens 8 can be increased, and the processing cost can be reduced. On the other hand, the eighth negative lens 8 in a meniscus shape can also effectively deflect and focus light onto the imaging surface 10, ensuring that the effective image height is consistent with the actual target surface height.

[0122] In some embodiments, the effective focal length f of the optical system, the arc θ of the maximum half field angle, and the real image height IH corresponding to the maximum field angle satisfy:

[0123] 0.45<(IH / 2) / (f×θ)<0.65.

[0124] In some embodiments, the maximum field of view FOV of the optical system and the aperture value FNO of the optical system satisfy:

[0125] 17<FOV / FNO<19.

[0126] The field of view angle can be ensured while ensuring that the F number of the system is large enough, thereby ensuring the amount of light entering the entire optical system and improving the brightness of the imaging surface 10.

[0127] In some embodiments, the material of the first positive lens 1 is preferably optical glass H-ZLAF96; the material of the second negative lens 2 is preferably optical glass H-LAK1; the material of the third negative lens 3 is preferably optical glass H-ZF73; the material of the fourth positive lens 4 is preferably optical glass H-ZLAF73; the material of the fifth positive lens 5 is preferably optical glass H-ZLAF96; the material of the sixth positive lens 6 is preferably optical glass H-LAK67; the material of the seventh negative lens 7 is preferably optical glass H-ZF73; the material of the eighth negative lens 8 is preferably optical glass H-LAK6A.

[0128] The high-performance airborne head-mounted low-light-level night vision optical system (hereinafter referred to as: optical system) provided by the present invention works in the 600-1100nm band, so that the focal length is 16.8mm, the F number is 1.4, the horizontal full field angle is 40.56°, the vertical full field angle is 32.5°, and the overall size is φ16×30mm. The high-performance airborne head-mounted low-light-level night vision optical system has the advantages of large relative aperture, low cost, good image quality, small size and light weight, and resistance to high and low temperatures.

[0129] Please see Figure 3 , is the point diagram of the optical system of the present invention. It can be seen that the RMS of the point diagram in the whole field of view is less than 9.7μm, and the GEO radius is less than 3 times the corresponding RMS radius, indicating that the aberration of the optical system is well corrected as a whole, and the image quality consistency at the center and edge of the field of view is relatively good.

[0130] Please see Figure 4 , is the optical modulation transfer function MTF curve diagram of the optical system in the present invention. It can be seen that the full-field MTF curve is relatively flat, and imaging at each frequency can be taken into account. Within the spatial frequency range of less than 52lp / mm, the optical modulation transfer function of the full field of view is higher than 0.4, indicating that the optical system has good imaging quality in terms of low-frequency contour, mid-frequency level and high-frequency details.

[0131] It should be noted that the MTF evaluation curve represents the relative change of modulation with spatial frequency (line pairs per millimeter, unit: lp / mm) during the imaging process, and is often used to evaluate the resolution of imaging lenses, such as Figure 4 and Figure 5 As shown, the abscissa in the figure represents the spatial frequency, and the ordinate in the figure represents the modulation degree (optical transfer function modulus).

[0132] Please see Figure 5 , are the spot diagram and optical modulation transfer function diagram of the optical system of the present invention at a high temperature of 70°C. Compared with room temperature, the spot diagram size and the MT optical modulation transfer function do not change significantly, which indicates that the system has the ability to resist high temperatures.

[0133] Please see Figure 6 , are the point diagram and optical modulation transfer function diagram of the optical system of the present invention at a low temperature of -55°C. Compared with room temperature, the point diagram does not change significantly, and the MTF optical modulation transfer function curve at 52lp / mm decreases by less than 0.1 compared with room temperature.

[0134] Please see Figure 7 , which is a distortion-field of view diagram of the present invention. It can be seen that under the full field of view, the distortion is controlled within 1.5%.

[0135] Specifically, the design parameters of each lens in the optical system provided by the present invention are exemplified below, as shown in Table 1, but the design parameters of each lens are not limited thereto, and other parameters in each data interval mentioned above are also within the protection scope of the present invention. The parameters in Table 1 are for reference only.

[0136] Table 1: Preferred parameters of each lens in the optical system provided by the present invention;

[0137]

[0138] The high-performance airborne head-mounted low-light night vision optical system (abbreviated as: optical system) provided by the present invention is composed of eight lenses and a filter, all of which are ordinary spherical lenses, and the materials are all domestic Chengdu Guangming materials, which are low in cost. In addition, the materials used are all low-expansion coefficient glass, which has a good high and low temperature resistance effect.

[0139] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered within the protection scope of the present invention. In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A high-performance airborne head-mounted low-light night vision optical system, characterized in that: Along the optical axis from the object side to the imaging surface, it includes: A first positive lens (1) having positive refractive power, wherein the object side surface (S1) of the first positive lens is a convex surface, and the image side surface (S2) of the first positive lens is a concave surface; A first glued component with negative optical power, wherein the object side of the first glued component is a concave surface, and the image side of the first glued component is a concave surface; A fourth positive lens (4) having positive power, wherein the object side surface (S6) of the fourth positive lens is a convex surface, and the image side surface (S7) of the fourth positive lens is a convex surface; A fifth positive lens (5) having positive power, wherein the object side surface (S8) of the fifth positive lens is a convex surface, and the image side surface (S9) of the fifth positive lens is a convex surface; Two glued components with negative optical power, the object side of the second glued component is concave, and the image side of the second glued component is convex; The eighth negative lens (8) has negative optical power, the object side surface (S13) of the eighth negative lens is a concave surface, and the image side surface (S14) of the eighth negative lens is a convex surface.

2. The high-performance airborne head-mounted low-light-level night vision optical system according to claim 1, characterized in that: The first bonding component comprises: A second negative lens (2) having negative optical power, wherein the object side surface (S3) of the second negative lens is a concave surface, and the image side surface (S4) of the second negative lens is a convex surface; The third negative lens (3) has negative optical power, the object side surface of the third negative lens is conformed to the image side surface (S4) of the second negative lens and is bonded by glue, and the image side surface (S5) of the third negative lens is a concave surface.

3. The high-performance airborne head-mounted low-light-level night vision optical system according to claim 2, characterized in that: The thickness of the second negative lens (2) is 0.998 mm; the optical focal length of the second negative lens (2) is -0.012; the refractive index of the second negative lens (2) is 1.66, and the Abbe number is between 57.34 and 57.35; the minimum air distance between the first positive lens (1) and the second negative lens (2) on the optical axis is 1.044 mm; The thickness of the third negative lens (3) is 1.047 mm, the optical focal length of the third negative lens (3) is -0.08; the refractive index of the third negative lens (3) is 1.96, and the Abbe number is 17.47; the minimum air distance between the third negative lens (3) and the fourth positive lens (4) on the optical axis is 2.392 mm.

4. The high-performance airborne head-mounted low-light-level night vision optical system according to claim 2, characterized in that: The second glued assembly comprises: A sixth positive lens (6) having negative optical power, wherein the object side surface (S10) of the sixth positive lens is a concave surface, and the image side surface (S11) of the sixth positive lens is a convex surface; The seventh negative lens (7) has positive focal power, the object side surface of the seventh negative lens and the image side surface (S11) of the sixth positive lens are conformed and bonded by glue, and the image side surface (S12) of the seventh negative lens is a convex surface.

5. The high-performance airborne head-mounted low-light-level night vision optical system according to claim 4, characterized in that: The thickness of the sixth positive lens (6) is 3.656 mm, the optical power of the sixth positive lens (6) is 0.077; the refractive index of the sixth positive lens (6) is 1.67, and the Abbe number is 51.74; The thickness of the seventh negative lens (7) is 3.134 mm, the optical focal length of the seventh negative lens (7) is -0.081; the refractive index of the seventh negative lens (7) is 1.96, and the Abbe number is 17.47; the minimum air distance between the seventh negative lens (7) and the eighth negative lens (8) on the optical axis is 4.689 mm.

6. The high-performance airborne head-mounted low-light-level night vision optical system according to claim 4, characterized in that: The surfaces of the first positive lens object side surface (S1), the first positive lens image side surface (S2), the second negative lens object side surface (S3), the third negative lens image side surface (S5), the fourth positive lens object side surface (S6), the fourth positive lens image side surface (S7), the fifth positive lens object side surface (S8), the fifth positive lens image side surface (S9), the sixth positive lens object side surface (S10), the seventh negative lens image side surface (S12), the eighth negative lens object side surface (S13) and the eighth negative lens image side surface (S14) are all coated with anti-reflection and anti-transmission films, and their reflectivity is not greater than 0.5% when the wavelength is between 600nm and 1000nm.

7. The high-performance airborne head-mounted low-light-level night vision optical system according to claim 1, characterized in that: It also includes a filter (9) and an imaging surface (10) which are arranged in sequence along the optical axis from the object side to the imaging surface; The filter (9) is arranged on the image side (S14) of the eighth negative lens, and the thickness of the filter (9) is 0.5 mm; the minimum air distance between the filter (9) and the eighth negative lens (8) on the optical axis is 0.1 mm; and the minimum air distance between the filter (9) and the imaging surface (10) on the optical axis is 0.5 mm.

8. The high-performance airborne head-mounted low-light-level night vision optical system according to claim 1, characterized in that: The optical power of the first positive lens (1) is 0.049; the thickness of the first positive lens (1) is 2.132 mm; the refractive index of the first positive lens (1) is 2.05, and the Abbe number is 26.99; The optical power of the fourth positive lens (4) is 0.075; the thickness of the fourth positive lens (4) is 2.569 mm; the refractive index of the fourth positive lens (4) is 1.88, and the Abbe number is 40.16; The optical power of the fifth positive lens (5) is 0.053; the thickness of the fifth positive lens (5) is 3.818 mm; the minimum air distance between the fourth positive lens (4) and the fifth positive lens (5) on the optical axis is 1.689 mm; the refractive index of the fifth positive lens (5) is 2.05, and the Abbe number is 26.99; The optical focal length of the eighth negative lens (8) is -0.064; the thickness of the eighth negative lens (8) is 1.140 mm; the refractive index of the eighth negative lens (8) is 1.69, and the Abbe number is 53.

38.

9. The high-performance airborne head-mounted low-light-level night vision optical system according to claim 1, characterized in that: The effective focal length f1 of the first positive lens (1) and the effective focal length f of the optical system satisfy: 1 <f1 / f<1.5; And / or, the optical system satisfies the following conditions: -2.5<(R11+R12) / (R11-R12)<-1; Wherein, R11 represents the curvature radius of the object side surface (S1) of the first lens, and R12 represents the curvature radius of the image side surface (S2) of the first lens; And / or, the effective focal length f of the optical system, the arc θ of the maximum half field angle, and the real image height IH corresponding to the maximum field angle satisfy: 0.45<(IH / 2) / (f×θ)<0.

65.

10. The high-performance airborne head-mounted low-light-level night vision optical system according to claim 1, characterized in that: The distortion of the full field of view of the optical system is less than 1.5%; the horizontal field angle of the optical system is not less than 40°, and the vertical field angle is not less than 30°.

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