Large-target-surface long-focus electrically tunable infrared lens

Abstract

The invention discloses a large-target-surface long-focus electrically tunable infrared lens, and relates to the technical field of optical lenses, the large-target-surface long-focus electrically tunable infrared lens comprises an optical system, the optical system is composed of a first lens, a second lens, protective glass and a sensor in sequence from front to back along the direction of an optical axis, the first lens and the second lens are both meniscus positive lenses, and the sensor is arranged on the first lens and the second lens. The first lens and the second lens are both made of chalcogenide glass materials, the total optical length of the optical system is 110 mm, and the opposite surface types of the first lens and the second lens are binary surfaces. The large-target-surface long-focus electrically tunable infrared lens disclosed by the invention has the technical effects that high image quality is realized, the detection view field is wider, and the lens cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of optical lens technology, and in particular to a large-area telephoto electrically adjustable infrared lens. Background Technology

[0002] In recent years, infrared lenses have been widely used in various fields such as security monitoring, driver assistance systems for automobiles and other vehicles, marine night vision navigation, law enforcement, anti-smuggling, search and rescue, border and coastal patrols, and reconnaissance. The requirements for their size, cost, and imaging performance are also increasing, making electrically tunable infrared lenses more convenient and flexible to use. Currently, the price of germanium is rising, causing lenses using germanium to become prohibitively expensive and unable to meet customer cost demands.

[0003] However, traditional infrared lenses use all-germanium infrared lenses, which are expensive and have low cost-effectiveness. Furthermore, the temperature refractive index of germanium varies greatly, resulting in poor image quality of infrared lenses at high temperatures of 80 degrees Celsius and low temperatures of -40 degrees Celsius. Summary of the Invention

[0004] This invention discloses a large-area telephoto electrically adjustable infrared lens, which aims to solve the technical problems of high cost and poor temperature adaptability leading to poor image quality in traditional infrared lenses.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A large-area telephoto electrically adjustable infrared lens includes an optical system. The optical system consists of a first lens, a second lens, a protective glass, and a sensor in sequence from front to back along the optical axis. Both the first lens and the second lens are meniscus lenses, and both the first lens and the second lens are made of chalcogenide glass material.

[0007] This design employs a two-piece lens, consisting of a first lens and a second lens, both made of chalcogenide materials. This significantly reduces lens costs. Chalcogenide materials have a small coefficient of refractive index change at temperature, resulting in better imaging quality at both high and low temperatures compared to germanium designs.

[0008] In a preferred embodiment, the total optical length of the optical system is 110 mm.

[0009] The optical system has a total optical length of 110mm, which is relatively short. It has the advantages of small size, light weight and compact structure, making it convenient for users to apply in various scenarios.

[0010] In a preferred embodiment, the opposing surfaces of the first lens and the second lens are both binary surfaces.

[0011] Two binary surfaces are used to meet the requirements of high image quality.

[0012] In a preferred embodiment, the optical system operates at wavelengths ranging from 8 μm to 12 μm and is adapted to a 1280 × 1024 12 μm detector.

[0013] By adopting the above technical solution, the optical system is adapted to a 1280×102412μm detector, which provides a wider field of view and meets the imaging requirements of large target surface and high image quality.

[0014] In a preferred embodiment, the first lens has a radius of curvature of 71 mm, a thickness of 10 mm, and a refractive index Nd of 2.77; the second lens has a radius of curvature of 29 mm, a thickness of 8 mm, and a refractive index Nd of 2.6.

[0015] As described above, a large-area telephoto electrically adjustable infrared lens includes an optical system. The optical system, from front to back along the optical axis, consists of a first lens, a second lens, a protective glass, and a sensor. Both the first and second lenses are meniscus lenses, and both are made of chalcogenide glass. The large-area telephoto electrically adjustable infrared lens provided by this invention achieves high image quality, a wider detection field of view, and reduced lens cost. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the optical system of a large-area telephoto electrically adjustable infrared lens proposed in this invention.

[0017] Figure 2 This is a distortion performance diagram of a large-area telephoto electrically adjustable infrared lens proposed in this invention.

[0018] Figure 3 This is a 20°C room temperature MTF performance diagram of a large-area telephoto electrically adjustable infrared lens proposed in this invention.

[0019] Figure 4 The MTF performance diagram at -40°C is shown for a large-area telephoto electrically adjustable infrared lens proposed in this invention.

[0020] Figure 5 This is a high-temperature MTF performance diagram of a large-area telephoto electrically adjustable infrared lens proposed in this invention at 80°C.

[0021] Figure 6 This is a dot diagram of a large-area telephoto electrically adjustable infrared lens proposed in this invention.

[0022] In the diagram: 1. First lens; 2. Second lens; 3. Protective glass; 4. Sensor. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0024] The large-area telephoto electrically adjustable infrared lens disclosed in this invention is mainly used in scenarios where traditional infrared lenses suffer from high cost and poor temperature adaptability, resulting in poor image quality.

[0025] Reference Figure 1 A large-area telephoto electrically adjustable infrared lens includes an optical system. The optical system consists of a first lens 1, a second lens 2, a protective glass 3, and a sensor 4 in sequence from front to back along the optical axis. Both the first lens 1 and the second lens 2 are meniscus lenses, and both the first lens 1 and the second lens 2 are made of chalcogenide glass material.

[0026] In practical use, the optical system runs from left to right through the center of all objects along the optical axis. From front to back along the optical axis, the first lens 1, the second lens 2, the protective glass 3, and the sensor 4 are arranged sequentially. This solution adopts a two-piece design, namely the first lens 1 and the second lens 2. Chalcogenide materials are used as the main materials for the first lens 1 and the second lens 2. Compared with traditional all-germanium infrared lenses, chalcogenide materials have lower costs and smaller temperature refractive index variation coefficients. This means that the lens can maintain more stable imaging quality under different temperature environments, such as high temperature of 80 degrees and low temperature of -40 degrees, while reducing the overall manufacturing cost.

[0027] The optical system has a total optical length of 110mm. The optical system has a short total length and the advantages of small size, light weight and compact structure, which makes it convenient for users to apply to various scenarios. The optical system has a focal length of 75mm and an F value of 1.0.

[0028] In this design, the relative surfaces of the first lens 1 and the second lens 2 are both binary surfaces. The binary surfaces are located at the second surface of the first lens 1 and the first surface of the second lens 2. The use of two binary surfaces meets the requirements for high image quality. In addition, aspherical lenses have different curvatures at different positions, which can more effectively correct aberrations and improve the imaging quality of the edge field of view compared with traditional spherical lenses. The binary surface design further optimizes the performance of the optical system by introducing a complex phase distribution, especially in terms of large target area and high image quality imaging.

[0029] The optical system operates at wavelengths from 8μm to 12μm and is compatible with 1280×102412μm detectors. This large target area design allows the lens to capture a wider field of view while maintaining high image quality. Through precise optical design and material selection, the lens achieves good imaging quality in both the central and peripheral fields of view, meeting the application requirements in various complex environments.

[0030] It should be noted that in the optical transfer function of an optical system, when the spatial frequency of the transfer function is 42p / mm, the MTF of the central field of view is ≥0.45, and it still has good imaging quality in the maximum field of view, while the MTF of the edge field of view is ≥0.38.

[0031] Reference Figure 1 In a preferred embodiment, the first lens 1 has a radius of curvature of 71 mm, a thickness of 10 mm, and a refractive index Nd of 2.77; the second lens 2 has a radius of curvature of 29 mm, a thickness of 8 mm, and a refractive index Nd of 2.6.

[0032] Reference Figure 1 In a preferred embodiment, the protective glass 3 has a thickness of 1 mm and a refractive index Nd of 4.0.

[0033] Specifically, the protective glass 3 with a high refractive index (Nd) of 4.0 forms a reasonable transition with the chalcogenide lens (refractive index 2.6-2.77), which can effectively reduce Fresnel reflection loss at the sensor 4 interface, keep the total optical length in a compact size of 110mm, and significantly improve the light energy utilization rate.

[0034] The protective glass 3 is coated with a diamond-like carbon (DLC) film with a thickness of 200-300nm and a hardness ≥HV2500, which is suitable for the packaging requirements of miniaturized infrared modules. As the outermost protective element of the infrared lens, the integrity of the protective glass 3 is crucial to the safety of the internal optical components. The DLC coating can enhance the physical and chemical properties of the protective glass 3, thereby more effectively protecting the internal optical components from external damage.

[0035] It should be noted that the optical system in this solution meets the following conditions:

[0036] Let the focal length of the optical system be f, and the focal lengths of the optical lenses from the first lens to the sensor 4 be f1 and f2 respectively. Then f and f1, f2 have the following relationship: 0.5 < |f / f1| < 0.7; 0.8 < |f / f2| < 1.

[0037] In optical systems, aspherical surfaces satisfy the following formula:

[0038]

[0039] Where f is the sag of the aspherical surface at a height of h along the optical axis from the vertex of the aspherical surface, R is the curvature of the aspherical surface, k is the conic coefficient, and A, B, C, D, E are all higher-order coefficients.

[0040] refer to Figure 2 The figure shows the percentage of the measured results for the wavelength with the maximum distortion at the 8-12µm operating wavelength.

[0041] refer to Figure 3 , Figure 4 and Figure 5 The MTF curves at room temperature (20°C), low temperature (-40°C), and high temperature (80°C) are shown respectively, verifying that the spatial frequency still has good imaging quality at 42 lp / mm.

[0042] Reference Figure 6 The dot plot confirms the "large target area telephoto" and demonstrates that the optical system meets the requirements for using a large target area infrared lens under normal operating conditions.

[0043] Working principle: In use, the optical system of this lens consists of a first lens 1 and a second lens 2, which are arranged sequentially from front to back along the optical axis. Both are meniscus lenses. The second surface of the first lens 1 and the first surface of the second lens 2 each contain two binary surfaces. This design helps to reduce aberrations and improve image quality. In addition, the lens is equipped with a protective glass 3 and a sensor 4. The protective glass 3 is used to protect the internal optical components from the influence of the external environment. The sensor 4 is responsible for receiving and converting optical signals into electrical signals for subsequent processing and analysis. The first lens 1 and the second lens 2 are made of chalcogenide glass, which can maintain more stable image quality while reducing the overall manufacturing cost.

[0044] It is worth noting that its unique design is as follows:

[0045] Chalcogenide materials ensure that the image quality of lenses is unaffected by temperature, primarily due to their low temperature coefficient of refractive index. Specifically, the reasons are as follows:

[0046] Refractive index stability:

[0047] Chalcogenide materials exhibit a small variation in refractive index with temperature, meaning they have a low temperature coefficient of refractive index. This implies that the refractive index of chalcogenide materials does not change significantly with temperature variations, thus maintaining a stable refraction path for light passing through the lens and reducing aberrations and image quality degradation caused by temperature changes.

[0048] Reduce aberrations:

[0049] In optical systems, aberrations are one of the important factors affecting image quality. Temperature changes may cause changes in the refractive index of lens materials, which in turn produce aberrations. Chalcogenide materials, due to their low temperature coefficient of refractive index, can effectively reduce such aberrations caused by temperature changes, ensuring that the lens can maintain clear image quality under different temperature environments.

[0050] Improve environmental adaptability:

[0051] This property of chalcogenide materials allows the lens to maintain stable imaging performance in extreme environments such as high temperatures of 80 degrees Celsius and low temperatures of -40 degrees Celsius, which is especially important for lenses that need to work outdoors or in complex environments for extended periods of time.

[0052] In summary, this solution achieves high image quality and significantly reduces lens costs by combining chalcogenide glass with binary surface processing technology.

[0053] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A large-area telephoto electrically adjustable infrared lens, comprising an optical system, wherein the optical system is composed of a first lens (1), a second lens (2), a protective glass (3), and a sensor (4) sequentially from front to back along the optical axis, characterized in that, Both the first lens (1) and the second lens (2) are meniscus lenses, and both the first lens (1) and the second lens (2) are made of chalcogenide glass.

2. The large-area telephoto electrically adjustable infrared lens according to claim 1, characterized in that, The total optical length of the optical system is 110 mm.

3. The large-area telephoto electrically adjustable infrared lens according to claim 1, characterized in that, The relative surface types of the first lens (1) and the second lens (2) are both binary surfaces.

4. The large-area telephoto electrically adjustable infrared lens according to claim 1, characterized in that, The optical system operates at wavelengths from 8μm to 12μm and is compatible with a 1280×102412μm detector.

5. A large-area telephoto electrically adjustable infrared lens according to claim 1, characterized in that, The optical system has a focal length of 75mm and an F-value of 1.

0.

6. The large-area telephoto electrically adjustable infrared lens according to claim 1, characterized in that, The first lens (1) has a radius of curvature of 71 mm, a thickness of 10 mm, and a refractive index of Nd of 2.

77.

7. A large-area telephoto electrically adjustable infrared lens according to claim 6, characterized in that, The second lens (2) has a radius of curvature of 29 mm, a thickness of 8 mm, and a refractive index of Nd of 2.

6.

8. A large-area telephoto electrically adjustable infrared lens according to claim 1, characterized in that, The protective glass (3) has a thickness of 1 mm and a refractive index of 4.0 Nd.

9. A large-area telephoto electrically adjustable infrared lens according to claim 8, characterized in that, The surface of the protective glass (3) is coated with a diamond-like carbon film.

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