A small optical passive athermalization for television band large field of view optical system

Abstract

This invention belongs to the field of optical imaging technology, and specifically to a small-scale passive pyrolysis optical system with a large field of view for television bands. It employs an evolved double-Gaussian structure, dividing the optical system into a front lens group and a rear lens group, distinguished by an aperture stop. Parallel incident light from the object plane passes through these groups sequentially. The optical system, in conjunction with the aluminum alloy lens barrel, achieves passive pyrolysis, enabling clear imaging on the focal plane without focusing within a temperature range of -45℃ to 60℃. This invention effectively solves the defocusing problem caused by thermal expansion and contraction of the lens barrel and changes in the refractive index of optical elements under high and low temperature environments. It offers advantages such as achieving passive pyrolysis over a wide temperature range, eliminating the need for an external focusing mechanism, reducing costs, and improving system reliability and stability.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, specifically to a small-scale passive thermal ablation optical system with a large field of view for television bands. Background Technology

[0002] In television optical imaging applications, when large field-of-view lenses operate in high and low temperature environments, the thermal expansion and contraction of the lens barrel material and the temperature-dependent refractive index changes of optical elements jointly cause defocusing problems, resulting in a significant decrease in image quality. Traditional solutions generally employ electromechanical active thermal compensation technology, which uses a focusing mechanism to drive the lens group or detector along the optical axis to compensate for thermal differences. While this method simplifies optical design, it requires the integration of electromechanical components such as motors, position sensors, and closed-loop control algorithms, significantly increasing system complexity, manufacturing costs, and potential failure points, thus weakening overall reliability. It is particularly unsuitable for scenarios with stringent requirements for lightweight design and high stability.

[0003] As an alternative, passive optical thermal aberration technology aims to coordinate parameters such as the linear expansion coefficient of the lens barrel, the refractive index / temperature coefficient of the lens material, and the linear expansion coefficient during the design phase, enabling the system to maintain clear imaging over a wide temperature range without external intervention. Theoretically, this method can achieve low-cost, highly robust, and compact systems. However, current practices have significant limitations: most designs rely on an excessive number of lenses to balance thermal and aberration differences, resulting in bulky structures and excessive weight; or they use special materials such as optical crystals and plastic aspherical surfaces, which not only increase raw material and processing costs but also affect long-term performance due to insufficient material stability; while some solutions introduce aspherical surfaces to optimize large field-of-view characteristics, the stringent manufacturing precision requirements lead to low yield rates, making it difficult to meet the needs of large-scale production.

[0004] Specifically, while the published patent CN119738958A achieves a 90° ultra-wide field of view, it does not address adaptability to high and low temperature environments; CN114063257A achieves a wide-angle, large aperture using aspherical lenses, but the material and manufacturing costs remain high; CN115268020B uses 12 lenses to achieve pyrography, resulting in redundant structure and difficulty in controlling size; CN206431356U and CN121500544A rely excessively on plastic aspherical lenses, limiting imaging accuracy and completely ignoring pyrography mechanisms; CN109061849B controls distortion to 2% and covers an 84° field of view, but lacks imaging assurance under temperature variations. These shortcomings collectively restrict the development of miniaturized, economical passive pyrography large field-of-view optical systems, especially in television band applications, where a solution is urgently needed that uses only conventional spherical lenses, has a reduced number of lenses, and requires no special materials, to balance wide-temperature stability, large field-of-view coverage, and manufacturing feasibility.

[0005] Therefore, we propose a small-scale passive thermal scaling optical system for television bands with large field of view to solve the above problems. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] To address the shortcomings of existing technologies, this invention provides a small-scale optical passive thermal ablation system with a large field of view for television bands. It provides a global surface glass lens that enables a small-scale optical system with good imaging quality in the 480nm–706nm television band, a field of view greater than 40°×40°, a detector focal plane diagonal of approximately 10mm, an F-number of 3.5, and a temperature range of -45℃ to 60℃. This achieves low cost and high reliability, solving the problems mentioned in the background art.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0010] A small, passively thermally ablated, large-field-of-view optical system for television bands employs an evolved double-Gaussian structure, dividing the optical system into a front lens group and a rear lens group, distinguished by an aperture stop. Parallel incident light from the object plane passes through these groups sequentially.

[0011] The front lens group consists of a meniscus negative lens of HZF73 glass, a meniscus positive lens of HZF52GT glass, a plano-concave negative lens of JGS1 fused silica glass, and a doublet formed by a meniscus negative lens of HZF73 glass and a biconvex positive lens of HZLAF69 glass.

[0012] After passing through the aperture stop, the lens group consists of a meniscus corrector with negative optical power made of HZF73 glass, a plano-convex positive lens made of HZPK7 glass, a biconvex positive lens made of HZPK7 material, and a plano-concave negative lens made of JGS1 fused silica glass.

[0013] The optical system, in conjunction with the aluminum alloy lens barrel, achieves passive thermal ablation, enabling clear imaging on the focal plane without focusing within a temperature range of -45℃ to 60℃.

[0014] Furthermore, its operating wavelength is 480nm~706nm, its field of view is greater than 40°×40°, its distortion is less than 5%, its detector focal plane diagonal is 10mm, and its F-number is 3.5, where the F-number is defined as the ratio of focal length f to entrance pupil diameter D: F=f / D=3.5.

[0015] Furthermore, the optical surfaces of all optical lenses are spherical.

[0016] Furthermore, to balance chromatic aberration and thermal aberration and reduce the range of incident angles in different fields of view, the meniscus negative lens uses HZF73 glass with a small coefficient of linear expansion, a small refractive index / temperature coefficient, a small Abbe number, and a large refractive index; the meniscus positive lens uses HZF52GT glass with a small coefficient of linear expansion, a small refractive index / temperature coefficient, a small Abbe number, and a large refractive index; and the combined focal length of the meniscus negative lens and the meniscus positive lens is negative.

[0017] Furthermore, the plano-concave negative lens uses fused silica JGS-1 glass with a negative refractive index / temperature coefficient, a small coefficient of linear expansion, a large Abbe coefficient, and a small refractive index to balance thermal and chromatic differences.

[0018] Furthermore, in the doublet lens, the meniscus negative lens is made of HZF73 glass with a high refractive index and a low Abbe coefficient, and the biconvex positive lens is made of HZLAF69 glass with a high refractive index and a medium Abbe coefficient. The linear expansion coefficients of the two are similar to avoid excessive stress on the bonding surface due to the difference in linear expansion coefficients at high and low temperatures.

[0019] Furthermore, the meniscus correction mirror uses HZF73 glass with a small refractive index / temperature coefficient, a large refractive index, a small Abbe coefficient, and a negative optical power to balance thermal and chromatic differences.

[0020] Furthermore, both the plano-convex positive lens and the biconvex positive lens are made of HZPK7 glass with a negative refractive index / temperature coefficient, a large coefficient of linear expansion, a large Abbe coefficient, and a large refractive index, in order to balance thermal difference and chromatic difference.

[0021] Furthermore, the plano-concave negative lens uses fused silica JGS-1 glass with a negative refractive index / temperature coefficient, a small coefficient of linear expansion, a large Abbe coefficient, and a small refractive index to correct field curvature and balance thermal and chromatic differences.

[0022] Furthermore, to balance the thermal difference, ordinary aluminum alloy (with a linear expansion coefficient of 23.6 × 10⁻⁶) was used. -6 / K) as the lens barrel material.

[0023] (III) Beneficial Effects

[0024] Compared with the prior art, the present invention provides a small-scale passive thermal ablation optical system with a large field of view for television bands, which has the following advantages:

[0025] This invention boasts a wide wavelength range, spanning 480nm to 706nm. It utilizes conventional optical glass and spherical lenses throughout, avoiding the use of aspherical lenses, which are difficult to manufacture and inspect, as well as plastic lenses with poor optical performance. The positive and negative optical power pairings and combinations of the heavy flint glass HZF73, heavy lanthanum flint glass HZLAF69, heavy phosphorus crown glass HZPK7, and fused silica JGS-1 materials satisfy the requirements of a wide television band range of 480nm to 706nm, a field of view greater than 40°×40°, a detector focal plane diagonal of approximately 10mm, and an F-number of 3.5. The full-temperature, full-field modulation transfer function (MTF) is greater than 0.2@220lp / mm.

[0026] This invention employs an evolved double Gaussian structure. Parallel light rays from different fields of view emanating from the object plane at infinity are shaped by the front group I between the object plane and the aperture stop, which reduces the angle between the incident light rays from different fields of view and greatly reduces the tilt angle with the optical axis. This reduces the field of view angle corresponding to the rear group between the aperture stop and the focal plane, i.e., the meniscus positive lens to the plano-concave negative lens, facilitating aberration correction. Based on the above principle, the image-side field of view is significantly reduced compared to the object-side field of view. At the same time, the aperture stop is placed as centrally as possible, reducing the maximum aperture of the optical system while obtaining smaller distortion, with the maximum vignetting coefficient not exceeding 5%. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a small-scale passive thermal ablation optical system with a large field of view for television band proposed in this invention.

[0028] Figure 2 This is a schematic diagram of the MTF curve of the present invention at a low temperature of -45℃.

[0029] Figure 3 This is a schematic diagram of the MTF curve of the present invention at room temperature (20°C).

[0030] Figure 4 This is a schematic diagram of the MTF curve of the present invention at a high temperature of 60°C.

[0031] Figure 5 This is the distortion diagram of the present invention.

[0032] In the diagram: 1. Object plane; 2. Meniscus negative lens; 3. Meniscus positive lens; 4. Plano-concave negative lens; 5. Meniscus negative lens; 6. Biconvex positive lens; 7. Aperture stop; 8. Meniscus negative lens; 9. Plano-convex positive lens; 10. Biconvex positive lens; 11. Plano-concave negative lens; 12. Detector focal plane; A. Cemented doublet; I. Front lens group; II. Rear lens group. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0034] Example

[0035] Traditional wide-field-of-view lenses for television bands typically employ electromechanical active pyrolysis to ensure image quality when used in high and low temperature environments. This not only increases system cost but also reduces system reliability. While optical passive pyrolysis technology can provide a low-cost, high-reliability, and high-quality imaging solution, current designs often result in an increased number of lenses, the use of special materials or aspherical surfaces, thereby increasing the complexity and manufacturing cost of the optical system.

[0036] In this regard, such as Figure 1-5 As shown, this application proposes a small-scale passive pyrolysis large-field optical system for television bands. It employs an evolved double-Gaussian structure, dividing the optical system into a front lens group I and a rear lens group II, distinguished by an aperture stop 7. Parallel incident light from the object plane 1 sequentially passes through a meniscus negative lens 2 of HZF73 glass, a meniscus positive lens 3 of HZF52GT glass, a plano-concave negative lens 4 of JGS1 fused silica glass, and a double-lens system composed of a meniscus negative lens 5 of HZF73 glass and a double-lens system of HZLAF69 glass. The doublet A formed by the convex positive lens 6 constitutes the front lens group I; after passing through the aperture stop 7, it sequentially passes through the meniscus corrector 8 of HZF73 glass with negative optical power, the plano-convex positive lens 9 of HZPK7 glass, the biconvex positive lens 10 of HZPK7 material, and the plano-concave negative lens 11 of JGS1 fused silica glass, constituting the rear lens group II; this optical system, in conjunction with the aluminum alloy lens barrel, achieves passive thermal aberration reduction, enabling clear imaging on the focal plane 12 without focusing within a temperature range of -45℃ to 60℃.

[0037] This embodiment provides a compact, passively thermally aberrated, large-field-of-view optical system for the television band. The system employs an evolved double-Gaussian structure, designed to achieve both a large field of view and passive thermal aberration performance through optimized lens configuration. For example, the structure can be composed of alternating arrangements of multiple positive and negative power lenses to effectively correct various aberrations.

[0038] The optical system is divided into a front lens group I and a rear lens group II, distinguished by an aperture stop 7. This division facilitates independent optimization of the performance of each lens group in the optical design. For example, the front lens group I can primarily be responsible for collecting light and initially correcting aberrations, while the rear lens group II can further correct residual aberrations and adjust the focal length. The aperture stop 7 can be placed at different locations within the optical system, for example, between the front lens group I and the rear lens group II, to control the system's light throughput and depth of field.

[0039] The front lens group I consists of multiple lens elements. The meniscus negative lens 2, made of common optical glass materials such as BK7 or K9 glass, provides negative optical power to help correct field curvature and distortion. The meniscus positive lens 3, made of common optical glass materials such as ZF1 or F2 glass, provides positive optical power to converge light and balance aberrations. The plano-concave negative lens 4, made of materials such as quartz glass or crown glass, introduces negative optical power to further correct aberrations. The cemented doublet A is formed by cementing a meniscus negative lens 5 and a biconvex positive lens 6. The meniscus negative lens 5 can be made of materials such as LaK9 or BaF10 glass, and the biconvex positive lens 6 can be made of materials such as SK16 or BaK4 glass. This cemented doublet A achieves preliminary correction of chromatic aberration and provides the required optical power by cementing together two glasses with different refractive indices and dispersion characteristics.

[0040] After passing through aperture stop 7, the light enters the rear lens group II. The rear lens group II also consists of multiple lens elements. Among them, the meniscus corrector 8 can be made of common optical glass materials such as SF6 glass or BaSF64 glass, and has a negative optical power. Its function is to further correct aberrations, especially higher-order aberrations. This optical system works in conjunction with an aluminum alloy lens barrel to achieve passive thermal aberration reduction.

[0041] Therefore, the optical system is designed to form a clear image on the focal plane 12 without focusing within a temperature range of -45°C to 60°C. For example, by selecting glass materials with different coefficients of thermal expansion and temperature coefficients of refractive index, and combining this with the material properties of the lens barrel, the system can maintain good image quality over a wide temperature range.

[0042] The optical system proposed in this application achieves clear imaging without focusing over a wide temperature range of -45℃ to 60℃ by employing an evolved double-Gaussian structure and a combination of specific optical materials, coupled with an aluminum alloy lens barrel. This system effectively avoids the increased cost and reduced reliability associated with traditional electromechanical active pyrolysis solutions, while overcoming the problems of numerous lenses, complex structures, or high costs associated with existing passive pyrolysis designs. It provides a miniaturized, low-cost, and stable performance solution for wide-field-of-view applications in the television band.

[0043] This application proposes a small-scale, passively pyrochemically ablated, large-field-of-view optical system for the television band. It achieves passive pyrochemical ablation through an evolved double-Gaussian structure and a specific combination of optical materials, coupled with an aluminum alloy lens barrel. However, the descriptions of these structures and materials alone are insufficient to fully define the specific performance boundaries and imaging quality levels of this optical system in practical applications. In real-world applications, users often have specific requirements for key performance indicators such as the operating band, field of view, image distortion, and detector compatibility. Without these specific parameters, it is difficult to assess whether the system can meet specific high-precision, large-area observation needs.

[0044] In this regard, this application further proposes that the working wavelength of the above-mentioned optical system is 480nm~706nm, the field of view is greater than 40°×40°, the distortion is less than 5%, the focal plane diagonal of the detector is 10mm, and the F number is 3.5, wherein the F number is defined as the ratio of focal length f to entrance pupil diameter D: F=f / D=3.5.

[0045] Specifically, the operating wavelength range is 480nm to 706nm, meaning that the optical system is designed to perform effective imaging within this specific spectral range. This wavelength range typically corresponds to the visible light region, ensuring that the system can capture color information visible to the human eye and optimize within this range to achieve good chromatic aberration correction and image quality.

[0046] A field of view greater than 40°×40° indicates that the optical system has a wide observation range. The field of view is a key parameter that measures the size of the spatial angles that an optical system can cover. A field of view greater than 40°×40° enables the system to perform target search, environmental monitoring, or macroscopic scene capture over a large area, greatly improving the system's application flexibility and efficiency.

[0047] Distortion less than 5% means that the degree of distortion of the image geometry by the optical system during the imaging process is strictly controlled. Distortion is a common aberration that causes straight lines in an image to become curved, or the proportions of image edges to be distorted. Controlling distortion to less than 5% ensures that the system can provide high-fidelity images, which is crucial for applications requiring precise measurement, target recognition, or image stitching.

[0048] The detector focal plane diagonal is 10mm, which refers to the diagonal size of the detector chip used to receive the image at the focal plane of the optical system. This parameter setting allows the optical system to be efficiently matched with image sensors of specific sizes (such as common CMOS or CCD sensors), thereby enabling miniaturization, lightweighting, and integration of the system, facilitating deployment in compact spaces.

[0049] An F-number of 3.5 is defined as the ratio of focal length f to entrance pupil diameter D: F = f / D = 3.5. The F-number is a measure of the relative aperture of an optical system, directly affecting its light throughput, depth of field, and resolution. An F-number of 3.5 means the system has moderate light throughput, capable of obtaining sufficiently bright images under certain lighting conditions, while achieving a good balance between aberration correction difficulty, system size, and cost. Lower F-numbers generally mean stronger light-gathering ability, but also increase the complexity of aberration correction.

[0050] Through the aforementioned technical solution, key performance parameters of the optical system, such as operating wavelength, field of view, distortion, detector focal plane diagonal, and F-number, are precisely defined, enabling the optical system of this application to achieve high-performance imaging in television band applications. Specifically, the operating wavelength of 480nm–706nm ensures that the system has good spectral response and chromatic aberration correction capabilities in the visible light range, thereby providing images with true colors and rich details. The large field of view of more than 40°×40° combined with low distortion of less than 5% allows the system to maintain the geometric accuracy and edge sharpness of the image while observing a wide range, avoiding the image distortion problem common in traditional large field-of-view systems and greatly improving the usability of the image. In addition, the setting of a detector focal plane diagonal of 10mm allows the system to be efficiently matched with mainstream small image sensors, realizing the miniaturization and integration of the system. The F-number configuration of 3.5 ensures sufficient light throughput for clear and bright images while balancing system size and aberration correction. This allows the system to achieve clear imaging on focal plane 12 without focusing over a wide temperature range of -45℃ to 60℃, providing stable and reliable observation capabilities even in harsh environments. This synergistic optimization of parameters enables the optical system of this application to meet the stringent application requirements of miniaturization, large field of view, and high imaging quality in the television band while maintaining passive pyrolysis characteristics.

[0051] In some embodiments described above in this application, a small-scale passive thermal correction optical system for television bands is proposed. This system achieves optical performance and thermal correction through the combination of multiple lenses. However, in actual manufacturing and assembly processes, the processing accuracy and cost control of optical components are key considerations. In particular, simplifying the manufacturing process and reducing costs while pursuing high performance is one of the challenges faced by this type of system.

[0052] In this regard, this application further proposes that all optical lenses in the aforementioned small-scale passive thermal ablation large-field-of-view optical system for television bands are designed with spherical surfaces. A spherical surface refers to an optical lens surface that is part of a sphere. Compared to aspherical surfaces, spherical surfaces have significant advantages such as mature processing technology, versatile manufacturing equipment, and simple testing methods. In the mass production of optical components, the processing efficiency and yield of spherical lenses are generally higher than those of aspherical lenses. Furthermore, the testing of spherical lenses typically uses an interferometer in conjunction with a standard sphere or standard cylindrical mirror, which offers high testing accuracy and relatively simple operation. Therefore, using spherical surfaces can effectively reduce the manufacturing cost of optical systems and shorten the production cycle.

[0053] By employing the aforementioned technical solution, all optical lenses in the optical system are designed with spherical surfaces, avoiding the complex processing techniques and high manufacturing costs associated with using aspherical lenses. This simplifies the entire optical system's manufacturing process, shortens the processing cycle, and effectively improves product yield. Despite using spherical surfaces, this application can still achieve passive thermal aberration reduction while maintaining wide field-of-view optical performance in the television band through optimized selection and combination of lens materials. This ensures clear imaging over a wide temperature range without the need for focusing, thereby significantly improving the system's economy and manufacturability while meeting performance requirements.

[0054] In some embodiments described above, a small-scale passive pyrometry-controlled large-field-of-view optical system for television bands is proposed. This system utilizes an evolved double-Gaussian structure to divide the optical system into a front lens group I and a rear lens group II, distinguished by an aperture stop 7. This, combined with an aluminum alloy lens barrel, achieves passive pyrometry control, enabling clear imaging on the focal plane 12 without focusing within a temperature range of -45°C to 60°C. However, in its implementation, designing such a large-field-of-view optical system, especially in the context of requiring passive pyrometry control, presents a complex and challenging problem: effectively balancing chromatic aberration and thermal aberration while simultaneously controlling the incident angle range across different fields of view. Simply selecting lens combinations may not simultaneously meet these stringent optical performance requirements, leading to a decrease in image quality over a wide temperature range and large field of view.

[0055] To address this, this application further proposes that, in order to balance chromatic aberration and thermal aberration and reduce the range of incident angles in different fields of view, the meniscus negative lens 2 is made of HZF73 glass with a small coefficient of linear expansion, a small refractive index / temperature coefficient, a small Abbe coefficient, and a large refractive index; the meniscus positive lens 3 is made of HZF52GT glass with a small coefficient of linear expansion, a small refractive index / temperature coefficient, a small Abbe coefficient, and a large refractive index; and the combined focal length of the meniscus negative lens 2 and the meniscus positive lens 3 is negative.

[0056] Specifically, the meniscus negative lens 2 uses HZF73 glass, which features a small coefficient of linear expansion, a small refractive index / temperature coefficient, a small Abbe number, and a large refractive index. The small coefficient of linear expansion helps reduce the expansion or contraction of the lens dimensions during temperature changes, thereby reducing thermal differences caused by changes in lens geometry. The small refractive index / temperature coefficient means that the glass's refractive index changes less with temperature, which is crucial for maintaining the stability of the system's optical performance at different temperatures and directly affects the thermal difference correction effect. A small Abbe number indicates that the glass has greater dispersion and is typically used in conjunction with glass with a large Abbe number to effectively correct chromatic aberration. The large refractive index helps achieve the required optical power at a smaller radius of curvature, potentially reducing the lens thickness and the overall system size. As the first element of the front lens group I, the negative optical power of the meniscus negative lens 2 helps diverge incident light, providing greater design freedom for subsequent elements and having an initial impact on the system's total focal length and field of view characteristics.

[0057] Meanwhile, the meniscus positive lens 3 uses HZF52GT glass, which also possesses the characteristics of a small coefficient of linear expansion, a small refractive index / temperature coefficient, a small Abbe number, and a large refractive index. Similar to HZF73 glass, these characteristics work together to reduce the impact of temperature changes on system performance, which is key to achieving passive pyrolysis. Its small Abbe number indicates its large dispersion, playing an important role in chromatic aberration correction. The large refractive index helps achieve the required optical power and may optimize the system structure. As the second element of the front lens group I, the positive optical power of the meniscus positive lens 3, together with the meniscus negative lens 2, performs preliminary convergence or divergence adjustment of the incident light rays and provides preliminary correction for the system's primary aberrations, such as spherical aberration, coma, astigmatism, and chromatic aberration.

[0058] Furthermore, the combined focal length of the meniscus negative lens 2 and the meniscus positive lens 3 is designed to be negative. This means that the lens group composed of these two lenses exhibits a divergent effect. Such a negative focal length combination is commonly used in optical systems to extend the field of view, correct aberrations, or serve as a front group of telescope objectives to provide a greater exit pupil distance or a wider field of view. In this application, this negative focal length combination helps to further reduce the range of incident angles in different fields of view, thereby reducing the burden on subsequent lens groups, simplifying the difficulty of overall aberration correction, and potentially contributing to a large field-of-view design. Simultaneously, by carefully selecting glass materials with specific thermo-optical properties, this negative focal length combination can also play a crucial role in thermal aberration correction.

[0059] Through the above technical solution, in the front lens group I, the combined focal length of the meniscus negative lens 2 and the meniscus positive lens 3 is designed to be negative. Glass materials with specific thermo-optical and dispersion characteristics are selected for these two lenses respectively. Specifically, the meniscus negative lens 2 uses HZF73 glass with a small coefficient of linear expansion, a small refractive index / temperature coefficient, a small Abbe number, and a large refractive index; the meniscus positive lens 3 uses HZF52GT glass with a small coefficient of linear expansion, a small refractive index / temperature coefficient, a small Abbe number, and a large refractive index. This application can effectively balance the chromatic aberration and thermal difference of the optical system. Specifically, the small coefficient of linear expansion and the small refractive index / temperature coefficient of these glass materials result in minimal changes in the geometric dimensions and refractive index of the lens over a wide temperature range (e.g., -45℃ to 60℃), thereby significantly reducing the thermal difference caused by temperature changes. Simultaneously, by rationally configuring glass with specific Abbe numbers, effective correction can be achieved for light of different wavelengths, thus realizing a good balance of chromatic aberration. Furthermore, the design of this negative combined focal length can effectively reduce the incident angle range of light in different fields of view. This not only helps to reduce the aberration correction burden of subsequent lens groups and simplify the overall optical design, but is also crucial for achieving large field of view imaging. It ensures the uniformity and sharpness of image quality in a wide field of view, thereby achieving clear imaging over a wide temperature range without focusing.

[0060] To address this, this application further proposes that the plano-concave negative lens 4 utilizes fused silica JGS-1 glass, which has a negative refractive index / temperature coefficient, a small coefficient of linear expansion, a large Abbe coefficient, and a small refractive index, in order to balance thermal and chromatic aberration. The plano-concave negative lens 4 is a negative power lens with one flat surface and one concave surface, primarily used in optical systems to diverge light, expand the field of view, and correct aberrations. As a key component in the front lens group I, its initial processing of the incident beam is crucial. Specifically, the fused silica JGS-1 glass has a negative refractive index / temperature coefficient, meaning its refractive index decreases slightly with increasing temperature. This plays a vital role in compensating for the increase in refractive index of other optical components in the system due to temperature increases, thereby effectively suppressing the drift of the optical system's focal length with temperature variations. Simultaneously, the material's small coefficient of linear expansion ensures the lens's dimensional stability over a wide temperature range, further reducing focal plane position changes caused by thermal expansion and contraction. Furthermore, the large Abbe coefficient of fused silica JGS-1 glass indicates excellent dispersion characteristics, contributing to effective chromatic aberration correction and ensuring better focusing of light of different wavelengths. Its lower refractive index also helps to optimize the overall aberration performance of the system.

[0061] By applying the above technical solution to the plano-concave negative lens 4 in the front lens group I, the unique combined advantages of its negative refractive index / temperature coefficient, small linear expansion coefficient, large Abbe coefficient, and low refractive index can be fully utilized. This allows the lens to provide precise compensation when temperatures change, working in conjunction with other optical components in the system to significantly improve the passive thermal aberration reduction capability of the entire optical system over a wide temperature range of -45℃ to 60℃. Simultaneously, its excellent dispersion characteristics effectively correct chromatic aberration, ensuring that in wide-field-of-view applications in the television band, the system can maintain clear and stable image quality without additional focusing, thereby improving the system's environmental adaptability and reliability.

[0062] In some embodiments described above in this application, a small-scale passive pyrolysis large-field-of-view optical system for television bands is proposed. The front lens group I of this system includes a cemented doublet A formed by a meniscus negative lens 5 and a biconvex positive lens 6. However, in practical applications, optical systems often need to operate over a wide temperature range. If the linear expansion coefficients of the two lenses in the cemented doublet A are mismatched, excessive thermal stress may be generated on the cemented surface under high and low temperature environments, thereby affecting the stability of the cemented surface, the long-term reliability of the optical system, and the imaging quality.

[0063] To address the aforementioned issues, this application proposes that, in the double-cemented lens A, the meniscus negative lens 5 is made of HZF73 glass with a high refractive index and a low Abbe coefficient, and the biconvex positive lens 6 is made of HZLAF69 glass with a high refractive index and a moderate Abbe coefficient. Furthermore, the linear expansion coefficients of the two lenses are similar, in order to avoid excessive stress on the cemented surface due to the difference in linear expansion coefficients at high and low temperatures.

[0064] Specifically, the meniscus negative lens 5 uses HZF73 glass, which has a high refractive index and a low Abbe coefficient. The high refractive index helps achieve the required negative optical power while maintaining a small radius of curvature, thus facilitating the correction of advanced aberrations. The low Abbe coefficient indicates that the glass has high dispersion, which is crucial for effectively correcting axial and lateral chromatic aberration when combined with glasses with different dispersion characteristics (such as HZLAF69 glass with a moderate Abbe coefficient). The biconvex positive lens 6 uses HZLAF69 glass, which also has a high refractive index, helping to provide the required optical power and control aberrations. Its moderate Abbe coefficient complements the low Abbe coefficient of the HZF73 glass, enabling the doublet A to achieve good achromatic effects over a wide spectral range. This combination balances the focal positions of different wavelengths of light, ensuring image sharpness. Furthermore, the linear expansion coefficients of the meniscus negative lens 5 and the biconvex positive lens 6 are designed to be similar. The linear expansion coefficient is the degree to which a material expands when heated or contracts when cooled. In a cemented doublet A, two lenses made of different materials are joined by an adhesive. If their coefficients of linear expansion differ significantly, the two lenses will expand or contract at different rates when the ambient temperature changes, resulting in shear or tensile stress at the bonding interface. By selecting HZF73 and HZLAF69 glass with similar coefficients of linear expansion, this differential expansion can be minimized, effectively reducing stress on the bonding surface under high and low temperature environments and preventing cracking, delamination, or degradation of optical performance.

[0065] Through the above technical solution, in the cemented doublet A, the meniscus negative lens 5 is made of HZF73 glass with a high refractive index and a small Abbe coefficient, while the biconvex positive lens 6 is made of HZLAF69 glass with a high refractive index and a medium Abbe coefficient. This combination of glass materials not only utilizes their respective refractive indices and dispersion characteristics to effectively balance chromatic aberration and spherical aberration of the optical system, ensuring imaging quality in the television band, but more importantly, by carefully selecting HZF73 and HZLAF69 glasses with similar coefficients of linear expansion, the stress generated at the cemented surface of the cemented doublet A due to inconsistent thermal expansion and contraction over a wide temperature range (e.g., -45℃ to 60℃) is significantly reduced. This effectively avoids problems such as cracking and delamination of the cemented surface, ensuring the structural stability and long-term reliability of the optical performance of the cemented doublet A. This ensures that the entire optical system can maintain clear imaging under extreme temperature conditions without focusing, further enhancing the passive thermal aberration reduction capability of the optical system.

[0066] In this regard, this application further proposes that in the above-mentioned optical system, the meniscus correction mirror 8 is made of HZF73 glass with a small refractive index / temperature coefficient, a large refractive index, a small Abbe coefficient, and a negative optical power, in order to balance thermal difference and chromatic difference.

[0067] Specifically, the meniscus correction mirror 8 is made of HZF73 glass. HZF73 glass is a material with specific optical and thermal properties. Its small refractive index / temperature coefficient means that the glass's refractive index fluctuates less with temperature changes, which is crucial for suppressing thermal differences in the optical system. Simultaneously, the glass has a relatively high refractive index, which helps to provide the necessary refractive power while maintaining a compact structure and offers greater design freedom for aberration correction. Furthermore, its small Abbe number indicates that the glass has relatively large dispersion, enabling it to effectively correct axial chromatic aberration and magnification chromatic aberration when used in conjunction with glass having a high Abbe number.

[0068] Meanwhile, the meniscus corrector 8 is designed with negative optical power. Lenses with negative optical power have the function of diverging light rays. In optical systems, negative optical power lenses are often used to correct field curvature, distortion, and are combined with positive optical power lenses to correct chromatic aberration and spherical aberration. Introducing a negative optical power element in the rear lens group II provides additional design freedom for the aberration balance of the entire system, playing a key role, especially in correcting higher-order aberrations and optimizing image quality.

[0069] Through the aforementioned technical solution, the meniscus corrector 8 in the rear lens group II is designed using HZF73 glass with negative optical power, which significantly improves the passive thermal aberration and chromatic aberration correction capabilities of the optical system. Specifically, the characteristics of HZF73 glass—low refractive index / temperature coefficient, high refractive index, and low Abbe coefficient—ensure that the optical performance of the meniscus corrector 8 remains relatively stable under temperature changes, effectively suppressing thermal aberration. Simultaneously, its high refractive index and low Abbe coefficient, combined with its negative optical power, allow it to work synergistically with other lens elements in the rear lens group II to finely correct residual axial chromatic aberration and magnification chromatic aberration. This combination of material and structural design enables the entire optical system to maintain clear image quality within a wide temperature range of -45℃ to 60℃ without any focusing operations, thereby greatly improving the system's environmental adaptability and practicality.

[0070] In some embodiments described above in this application, a small-scale passive pyrolysis optical system with a large field of view for television bands is proposed. This system aims to achieve passive pyrolysis over a wide temperature range through an evolved double-Gaussian structure and specific lens combinations. However, in practical applications, ensuring excellent imaging quality across the entire optical system within a temperature range of -45°C to 60°C is crucial, especially for the key positive lens elements in the rear lens group. The choice of materials is critical for balancing thermal and chromatic aberration; improper material selection may lead to a decline in imaging performance at extreme temperatures.

[0071] In this regard, this application further proposes that in the above-mentioned small-scale passive thermal ablation optical system for television band, the plano-convex positive lens 9 and the biconvex positive lens 10 are both made of HZPK7 glass with a negative refractive index / temperature coefficient, a large linear expansion coefficient, a large Abbe coefficient, and a large refractive index, in order to balance thermal difference and chromatic difference.

[0072] Specifically, the plano-convex positive lens 9 and the biconvex positive lens 10 are key positive power elements in the rear lens group II, playing a crucial role in the overall focal length and aberration correction of the system. HZPK7 glass was chosen as the material for these two lenses based on its unique optical and thermal properties. HZPK7 glass has a negative refractive index / temperature coefficient, meaning that its refractive index decreases as the ambient temperature rises, resulting in a reduction in its optical power. This characteristic is contrary to the trend of most optical materials where the refractive index increases with temperature, effectively compensating for focal length drift caused by temperature changes and is one of the key factors in achieving passive thermal aberration reduction. Simultaneously, HZPK7 glass has a large coefficient of linear expansion, making the lens size change more significantly with temperature. When used with an aluminum alloy lens barrel, this expansion or contraction can be cleverly utilized to fine-tune the air gap between lenses or the relative position of the lenses to the lens barrel, further assisting in thermal aberration compensation at different temperatures. Furthermore, HZPK7 glass has a large Abbe number, indicating lower dispersion, which helps reduce axial and transverse chromatic aberration in the optical system, improving image sharpness. Its higher refractive index can provide stronger optical power, thereby reducing the radius of curvature or thickness of the lens while achieving the same optical function. This is beneficial for the miniaturization of optical systems and helps to correct advanced aberrations.

[0073] Through the above technical solution, HZPK7 glass with specific optical and thermal properties is selected for the plano-convex positive lens 9 and biconvex positive lens 10 in the rear lens group II. Its negative refractive index / temperature coefficient and large coefficient of linear expansion can effectively compensate for focal length drift and aberration changes caused by temperature variations over a wide temperature range, thereby achieving passive thermal balance. Simultaneously, its large Abbe coefficient and high refractive index help to effectively correct chromatic aberration while maintaining system compactness. This material selection strategy ensures that the optical system maintains clear and stable imaging quality under extreme temperature conditions ranging from -45℃ to 60℃, without the need for additional focusing, significantly improving the system's environmental adaptability and reliability.

[0074] In some embodiments described above in this application, a small-scale passive pyrometry correction optical system for television bands with a large field of view is proposed. This system, through an evolved double-Gaussian structure and a specific combination of lens materials, aims to achieve clear imaging over a wide temperature range. However, in practical applications, especially under conditions of large field of view and wide temperature variations, the optical system may still face the problem of insufficient simultaneous correction of field curvature, thermal aberration, and chromatic aberration, which may affect image quality and system stability.

[0075] In this regard, this application further proposes that in the rear lens group II of the optical system, the plano-concave negative lens 11 is made of fused silica JGS-1 glass with a negative refractive index / temperature coefficient, a small coefficient of linear expansion, a large Abbe coefficient, and a small refractive index, in order to correct field curvature and balance thermal and chromatic differences.

[0076] Specifically, the plano-concave negative lens 11 is a key optical element in the rear lens group II. It possesses negative optical power and is primarily used for diverging rays. In optical systems, negative lenses are commonly used to correct aberrations, particularly field curvature and spherical aberration. Its plano-concave geometry helps provide the necessary negative optical power while maintaining system compactness and allowing for fine-tuning of the optical path. Fused silica JGS-1 glass is a high-performance optical material characterized by its excellent physical and optical properties. Specifically, its refractive index / temperature coefficient is negative, meaning that its refractive index decreases slightly with increasing temperature, which is crucial for balancing thermal differences in the optical system. Simultaneously, fused silica JGS-1 glass has a low coefficient of linear expansion, which helps reduce lens size changes caused by temperature variations, thereby improving the system's thermal stability. Furthermore, its large Abbe number indicates low dispersion, which is beneficial for correcting chromatic aberration. Its relatively low refractive index provides greater freedom in optical design, allowing it to be combined with other high-refractive-index materials to achieve superior aberration correction. Field curvature correction refers to the phenomenon where, during imaging, a point on the object plane fails to form a sharp image on the image plane, instead creating a curved image surface. By appropriately selecting the shape and material of the lens, field curvature can be effectively corrected, making the image surface flatter. Thermal aberration balancing refers to passively reducing thermal aberration by selecting materials with specific thermo-optical properties over a wide temperature range to keep parameters such as the focal length and image plane position of the optical system relatively stable with temperature changes. Chromatic aberration balancing refers to combining optical materials with different dispersion characteristics to converge light of different wavelengths at the same position on the image plane, eliminating image blur caused by wavelength differences.

[0077] In this regard, this application further proposes that the coefficient of linear expansion of the aluminum alloy lens barrel is 23.6 × 10⁻⁶. -6 / K.

[0078] In optical systems, the primary function of the lens barrel is to precisely fix and support the various optical elements, maintaining strict relative positional accuracy between them. Aluminum alloys are often chosen as materials for optical lens barrels due to their lightweight, high strength, ease of machining, and good thermal conductivity. Their structural stability is crucial for the imaging quality of the optical system. The coefficient of linear expansion is a physical quantity that measures the degree of thermal expansion or thermal contraction of a material. For optical systems, the coefficient of linear expansion of the lens barrel directly affects the change in the distance between optical elements with temperature. The coefficient of linear expansion of the aluminum alloy lens barrel is precisely set to 23.6 × 10⁻⁶. -6 / K is based on the passive thermal aberration design requirements of the entire optical system. This specific value is the result of precise calculations and material selection, designed to match the glass material properties of the optical elements and the overall optical power variation trend of the system, to ensure that the focal plane position and image quality of the optical system remain stable when the temperature changes.

[0079] The following example will provide a more detailed explanation of the above technical solution:

[0080] Imagine a scenario where User A needs to perform real-time television band monitoring of a wide outdoor area with a broad temperature range, ranging from -45°C in the cold winter to 60°C in the hot summer. This monitoring system requires a compact optical system with a wide field of view that can maintain image clarity across the entire temperature range without manual or electromechanical focusing, while avoiding the use of expensive aspherical lenses or complex active focusing mechanisms.

[0081] This optical system employs an evolved double-Gaussian structure, dividing the optical path into a front lens group I and a rear lens group II, distinguished by an aperture stop 7. When parallel rays from object plane 1 enter the system, they first pass through front lens group I. Front lens group I consists of a series of lenses with carefully selected materials and surface shapes to initially correct aberrations and lay the foundation for subsequent passive thermal aberration reduction.

[0082] Specifically, the light first enters the meniscus negative lens 2 made of HZF73 glass. This lens uses HZF73 glass, characterized by its low coefficient of linear expansion, low refractive index / temperature coefficient, low Abbe number, and high refractive index. This helps balance the chromatic and thermal aberrations of the system and control the range of incident angles for different fields of view. Next, the light passes through the meniscus positive lens 3 made of HZF52GT glass. HZF52GT glass also possesses the characteristics of a low coefficient of linear expansion, low refractive index / temperature coefficient, low Abbe number, and high refractive index. The combined focal length of the meniscus negative lens 2 and the meniscus positive lens 3 is designed to be negative to further optimize aberration correction. Subsequently, the light passes through the plano-concave negative lens 4 made of JGS1 fused silica glass. JGS1 fused silica glass has a negative refractive index / temperature coefficient, a low coefficient of linear expansion, a high Abbe number, and a low refractive index, which effectively balances the thermal and chromatic aberrations of the system. The final part of the front lens group I is a cemented doublet A, which is cemented together with a meniscus negative lens 5 made of HZF73 glass and a biconvex positive lens 6 made of HZLAF69 glass. The meniscus negative lens 5 is made of HZF73 glass, which has a high refractive index and a low Abbe number, while the biconvex positive lens 6 is made of HZLAF69 glass, which has a high refractive index and a moderate Abbe number. The linear expansion coefficients of these two types of glass were chosen to be similar to avoid excessive stress on the cemented surface due to the difference in the material expansion coefficients under extreme high and low temperature environments, thereby ensuring the long-term stability of the optical system.

[0083] After the initial light processing is completed by the front lens group I, the light passes through the aperture stop 7. Aperture stop 7 is located inside the system and is used to control the F-number of the system and further divide the system into front and rear groups. This system is designed with an F-number of 3.5, which ensures sufficient light transmission while also maintaining a compact system.

[0084] After passing through aperture stop 7, the light enters the rear lens group II. The rear lens group II first consists of a meniscus corrector 8 made of HZF73 glass, with a negative optical power. This lens uses HZF73 glass, which has a small refractive index / temperature coefficient, a large refractive index, and a small Abbe coefficient. Its negative optical power design further balances the thermal and chromatic aberration of the system. Subsequently, the light passes sequentially through a plano-convex positive lens 9 made of HZPK7 glass and a biconvex positive lens 10 made of HZPK7 material. Both the plano-convex positive lens 9 and the biconvex positive lens 10 use HZPK7 glass, which has a negative refractive index / temperature coefficient, a large coefficient of linear expansion, a relatively large Abbe coefficient, and a large refractive index, playing a crucial role in balancing thermal and chromatic aberration. Finally, the light passes through a plano-concave negative lens 11 made of JGS1 fused silica glass. This lens uses fused silica JGS-1 glass, which has a negative refractive index / temperature coefficient, a small coefficient of linear expansion, a large Abbe coefficient, and a small refractive index. Its main function is to correct the field curvature of the system and further balance thermal and chromatic aberration.

[0085] The entire optical system is precisely mounted in a lens barrel made of aluminum alloy. The linear expansion coefficient of this aluminum alloy lens barrel is 23.6 × 10⁻⁶. -6 / K. The selection of the lens barrel material and the properties of all optical lens materials (including refractive index / temperature coefficient and coefficient of linear expansion) have been comprehensively considered and optimized to enable the system to achieve passive pyrolysis over a wide temperature range of -45℃ to 60℃. This means that even with drastic changes in ambient temperature, the optical system can stably present a clear image on focal plane 12 without any focusing operation. This passive pyrolysis technology avoids the electromechanical active focusing mechanisms commonly found in existing technologies, thereby reducing system cost, complexity, and power consumption, and improving reliability.

[0086] This optical system operates in the 480nm–706nm wavelength range, covering the main range of television wavelengths. Its field of view is greater than 40°×40°, meeting the needs of large-field-of-view monitoring, and its distortion is less than 5%, ensuring the geometric accuracy of the image. The detector's focal plane diagonal is 10mm, consistent with its miniaturized design. All optical lenses have spherical surfaces, unlike existing technologies that often use aspherical surfaces to achieve large fields of view or thermal aberration. This avoids the high cost and potential precision issues associated with aspherical processing, thus reducing manufacturing costs and complexity while maintaining performance. Through the synergistic effect of the lens materials, surface shapes, combination methods, and barrel materials, this system achieves passive thermal aberration and large-field-of-view imaging over a wide temperature range without increasing complexity or cost, solving the problems of complex and expensive active focusing systems or limited performance of passive systems in existing technologies.

[0087] See Figure 1 The described small-scale passive thermal ablation large-field optical system for television bands includes: nine lenses arranged sequentially from the object plane 1 at infinity to the focal plane 12, including a cemented doublet A and an aperture 7 that limits the beam diameter.

[0088] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0089] In the description of this invention, it should be understood that the terms "crescent," "plano-convex," "plano-concave," "biconvex," "biconcave," "positive lens," "negative lens," "front group," "rear group," "aperture," "focal plane," "object plane," "incident light," "cemented doublet," "lens group," "double Gaussian," "first surface," and "second surface," etc., indicating shapes or positional relationships based on the shapes or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, terms such as "F-number," "MTF," "lp / mm," "thermal difference," "chromatic aberration," "focusing," "field lens," "field curvature," and "distortion," etc., are common professional terms for those skilled in the art, and their specific meanings in this invention can be understood through specific contexts.

[0090] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the glass material grades or terms "HZF", "JGS-1", "HZLAF", and "HZPK" should be interpreted broadly. For example, they can refer to HZF52GT, or domestic materials such as HZF52, HZF52A, and HZF52TT, or foreign materials with similar refractive indices and Abbe coefficients (accurate to four decimal places) and similar coefficients of linear expansion and temperature refractive index coefficients (error not exceeding 10%). Fused silica JGS-1 glass material is somewhat special. The other two domestic grades, such as JGS-2 and JGS-3, have the same optical and physicochemical properties as JGS-1, differing only in transmittance. Therefore, domestic fused silica JGS-1, JGS-2, and JGS-3, and foreign brands such as Corning 7980 and 7979, which have the same optical and physicochemical properties, can be considered as the same type of material. Those skilled in the art can understand the specific meaning of the above terms in this invention through specific circumstances.

[0091] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0092] like Figure 1 As shown, the present invention proposes a small-scale passive thermal ablation large-field optical system for television bands. Along the propagation direction of light 1, a double cemented lens A is formed by combining a meniscus negative lens 2 of HZF73 glass, a meniscus positive lens 3 of HZF52GT glass, a plano-concave negative lens 4 of JGS-1 fused silica glass, a meniscus negative lens 5 of HZF73 glass, and a biconvex positive lens 6 of HZLAF69 glass, and an aperture stop 7, which together form the front group I of the double Gaussian lens structure. After the light is shaped by the front group, the incident angle range and aperture are reduced. Then, the light passes through the rear group II, which is composed of a meniscus negative lens 8 of HZLAF69 glass, a plano-convex positive lens 9 of HZPK7 glass, a biconvex positive lens 10 of HZPK7 glass, and a plano-concave negative lens 11 of JGS-1 fused silica glass, and finally the image is formed on the focal plane 12.

[0093] Choosing the above material combination allows for thermal ablation when combined with an aluminum alloy lens barrel with a linear expansion coefficient of 23.6×10-6 / K at temperatures ranging from -45℃ to 60℃. This means that image quality can be maintained at MTF≥0.2@220lpmm across the entire field of view without the need for focusing.

[0094] Implementation Cases

[0095] It employs a visible light detector with a focal plane of 7.2mm × 7.2mm (diagonal approximately 10mm), an adaptable wavelength of 480nm~706nm, a full field of view of 40°×40°, an F-number of 3.5, a focal length of 10mm, a total of nine lenses, an aluminum alloy lens barrel, a thermal difference range of -45℃~60℃, distortion <5%, a cutoff frequency of 220lp / mm, and a total system weight of no more than 3.5g.

[0096] Table 1 (Unit: mm)

[0097]

[0098] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0099] As can be seen from the above, the small-sized passive pyrolysis optical system with a large field of view provided in this application for television band adopts an evolved double Gaussian structure, consisting of a front lens group and a rear lens group, which work together with an aluminum alloy lens barrel to achieve passive pyrolysis. It can achieve clear imaging without focusing within a temperature range of -45℃ to 60℃, thereby effectively solving the defocusing problem caused by thermal expansion and contraction of the lens barrel and changes in the refractive index of optical elements under high and low temperature environments. It has the advantages of achieving passive pyrolysis in a wide temperature range, eliminating the need for an external focusing mechanism, reducing costs, and improving system reliability and stability.

[0100] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A small-scale passive thermal ablation optical system for television bands with a large field of view, characterized in that: An evolved double Gaussian structure is used to divide the optical system into a front lens group (I) and a rear lens group (II), which are distinguished by an aperture stop (7). Parallel incident light from the object plane (1) passes through the following sequentially: The front lens group (Ⅰ) consists of a meniscus negative lens (2) of HZF73 glass, a meniscus positive lens (3) of HZF52GT glass, a plano-concave negative lens (4) of JGS1 fused silica glass, and a doublet lens (A) formed by a meniscus negative lens (5) of HZF73 glass and a biconvex positive lens (6) of HZLAF69 glass. After passing through the aperture stop (7), the lens group (Ⅱ) is formed by passing through the meniscus correction lens (8) of HZF73 glass with negative optical power, the plano-convex positive lens (9) of HZPK7 glass, the biconvex positive lens (10) of HZPK7 material, and the plano-concave negative lens (11) of JGS1 fused silica glass. The optical system, in conjunction with the aluminum alloy lens barrel, achieves passive thermal ablation, enabling clear imaging onto the focal plane without focusing within a temperature range of -45℃ to 60℃ (12).

2. The small-scale passive thermal ablation optical system for television bands with a large field of view according to claim 1, characterized in that: Its operating wavelength range is 480nm~706nm, the field of view is greater than 40°×40°, the distortion is less than 5%, the focal plane diagonal of the detector is 10mm, and the F number is 3.5, where the F number is defined as the ratio of focal length f to entrance pupil diameter D: F=f / D=3.

5.

3. The small-scale passive thermal ablation optical system for television bands with a large field of view according to claim 1, characterized in that: All optical lenses have spherical surfaces.

4. The small-scale passive thermal ablation optical system for television bands with a large field of view according to claim 1, characterized in that: To balance chromatic aberration and thermal aberration and reduce the range of incident angles in different fields of view, the meniscus negative lens (2) is made of HZF73 glass with a small coefficient of linear expansion, a small refractive index / temperature coefficient, a small Abbe coefficient, and a large refractive index; the meniscus positive lens (3) is made of HZF52GT glass with a small coefficient of linear expansion, a small refractive index / temperature coefficient, a small Abbe coefficient, and a large refractive index; and the combined focal length of the meniscus negative lens (2) and the meniscus positive lens (3) is negative.

5. A small-scale passive thermal ablation optical system for television bands with a large field of view, as described in claim 1, characterized in that: The plano-concave negative lens (4) uses fused silica JGS-1 glass with a negative refractive index / temperature coefficient, a small coefficient of linear expansion, a large Abbe coefficient, and a small refractive index to balance thermal and chromatic differences.

6. The small-scale passive thermal ablation optical system for television bands with a large field of view according to claim 1, characterized in that: In the double cemented lens (A), the meniscus negative lens (5) is made of HZF73 glass with a large refractive index and a small Abbe coefficient, and the biconvex positive lens (6) is made of HZLAF69 glass with a large refractive index and a medium Abbe coefficient. The linear expansion coefficients of the two are similar to avoid excessive stress on the cemented surface due to the difference in linear expansion coefficients at high and low temperatures.

7. A small-scale passive thermal ablation optical system for television bands with a large field of view, as described in claim 1, characterized in that: The meniscus correction mirror (8) uses HZF73 glass with a small refractive index / temperature coefficient, a large refractive index, a small Abbe coefficient, and a negative optical power to balance thermal and chromatic differences.

8. A small-scale passive thermal ablation optical system for television bands with a large field of view, as described in claim 1, characterized in that: Both the plano-convex positive lens (9) and the biconvex positive lens (10) are made of HZPK7 glass with a negative refractive index / temperature coefficient, a large linear expansion coefficient, a large Abbe coefficient, and a large refractive index, in order to balance thermal difference and color difference.

9. A small-scale passive thermal ablation optical system for television bands with a large field of view, as described in claim 1, characterized in that: The plano-concave negative lens (11) uses fused silica JGS-1 glass with a negative refractive index / temperature coefficient, a small coefficient of linear expansion, a large Abbe coefficient, and a small refractive index to correct field curvature and balance thermal and chromatic differences.

10. A small-scale passive thermal ablation optical system for television bands with a large field of view, as described in claim 1, characterized in that: The coefficient of linear expansion of the aluminum alloy lens barrel is 23.6 × 10⁻⁶. -6 / K.

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