An optical lens

Abstract

This disclosure discloses an optical lens and an infrared vehicle-mounted lens. The optical lens includes: a first lens with positive optical power, which is a meniscus lens with a convex object side and is made of silicon; a second lens with negative optical power, which is also a meniscus lens with a convex object side; and a third lens with positive optical power, which is either a biconvex lens or a meniscus lens with a concave object side. The embodiments disclosed herein can eliminate aberrations, thereby achieving an optical lens with good image quality. Furthermore, the silicon first lens, combined with a heating element, can achieve heated defogging, saving on the manufacturing cost and space required by traditional protective windows.

Description

Technical Field

[0001] This disclosure generally relates to the field of optical technology. More specifically, this disclosure relates to an optical lens and an infrared automotive lens. Background Technology

[0002] With the improvement of automotive safety standards and the development of autonomous driving technology, the automotive industry has placed higher demands on the optical lenses used in functional units such as advanced driver assistance systems, autonomous driving systems, night vision systems, and driver monitoring systems.

[0003] Taking infrared vehicle-mounted night vision systems as an example, they are used to enhance driver vision at night or in low-visibility conditions, improving driving safety. Infrared vehicle-mounted night vision systems utilize infrared imaging principles, including imaging by detecting the thermal radiation of natural objects and imaging by illuminating targets with infrared light sources and capturing the reflected infrared light. For safety reasons, infrared vehicle-mounted night vision systems require optical lenses to achieve good image quality so that the detector can capture clear images.

[0004] Therefore, there is an urgent need to provide an optical lens solution to eliminate imaging aberrations and achieve good image quality. Utility Model Content

[0005] In order to at least address one or more of the technical problems mentioned above, this disclosure proposes optical lens solutions in several aspects.

[0006] In a first aspect, this disclosure provides an optical lens comprising: a first lens having positive optical power, which is a meniscus lens with a convex object side, the first lens being made of silicon; a second lens having negative optical power, which is a meniscus lens with a convex object side; and a third lens having positive optical power, which is a biconvex lens or a meniscus lens with a concave object side.

[0007] In some embodiments, the optical parameters of the first lens satisfy the following condition: 0.23≤|e1 / d1|≤0.61, where e1 represents the edge distance of the first lens and d1 represents the center thickness of the first lens.

[0008] In some embodiments, the optical parameters of the first lens satisfy the following conditions: 0.82≤|f1 / f|≤2.52, 0.23≤|e1 / d1|≤0.61; the optical parameters of the second lens satisfy the following conditions: 0.66≤|f2 / f|≤2.20; and the optical parameters of the third lens satisfy the following conditions: 0.57≤|f3 / f|≤0.70, where f represents the total focal length of the optical lens, f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, and f3 represents the focal length of the third lens. In some embodiments, the optical parameters of the optical lens satisfy the following condition: 1.00≤f×(n-1) / (FNO×R1)≤2.55; where FNO represents the F-number of the optical lens, n represents the refractive index of the first lens, and R1 represents the radius of curvature of the object-side surface of the first lens.

[0009] In some embodiments, the optical parameters of the optical lens satisfy the following condition: 0.95≤|R1 / f|≤2.51; where R1 represents the radius of curvature of the object-side surface of the first lens.

[0010] In some embodiments, the optical parameters of the optical lens satisfy the following condition: 2.97≤|FOV / f|≤4.42; where FOV represents the horizontal field of view of the optical lens.

[0011] In some embodiments, the optical parameters of the optical lens satisfy one or more of the following conditions: 1.20≤|D / ENPD|≤1.33; 1.13≤|D1 / f|≤1.43; where D represents the maximum lens aperture in the optical lens, ENPD represents the entrance pupil diameter of the optical lens, and D1 represents the aperture of the first lens.

[0012] In some embodiments, the optical parameters of the optical lens satisfy one or more of the following conditions: 0.28≤|BFL / TTL|≤0.36; 1.46≤|TTL / f|≤1.87; where BFL represents the distance from the image-side surface of the third lens to the image plane of the optical lens, and TTL represents the distance from the center of the object-side surface of the first lens to the imaging plane of the optical lens.

[0013] In some embodiments, the second lens is made of germanium glass or chalcogenide glass, and the third lens is made of chalcogenide glass.

[0014] In a second aspect, this disclosure provides an infrared vehicle-mounted lens comprising: a heating element and an optical lens as described in any of the first aspects, wherein the heating element is disposed on the image side of a first lens made of silicon in the optical lens and is used to heat the optical lens to remove fog; a heat insulation structure is attached behind the heating element.

[0015] With the optical lens provided above, this embodiment utilizes the convex surface of a first lens with positive optical power to collect as much light as possible, and the convex surface of a second lens with negative optical power to collect the light emitted from the first lens, ensuring that as much light as possible is retained in the optical lens, thereby guaranteeing the light intensity used for imaging. The concave surface of the second lens, serving as the image-side surface, allows for a smooth transition of the emitted light and facilitates the correction of light in each field of view. The positive optical power third lens facilitates light convergence. The reasonable allocation of focal lengths among the first, second, and third lenses better eliminates aberrations, thereby achieving good image quality. Furthermore, the use of a silicon-based first lens allows the optical lens to be directly heated and defogging by a heating element, simplifying the protective structure in existing optical lenses and reducing costs and lens size. Attached Figure Description

[0016] The above and other objects, features, and advantages of exemplary embodiments of this disclosure will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of this disclosure are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein:

[0017] Figure 1 An exemplary structural diagram of an optical lens according to some embodiments of this disclosure is shown;

[0018] Figure 2 Exemplary structural diagrams of optical lenses according to other embodiments of this disclosure are shown;

[0019] Figure 3 A schematic diagram of the optical structure of the first optical lens in this disclosure is shown;

[0020] Figure 4 A blur pattern of the first optical lens in this disclosure is shown;

[0021] Figure 5 The distortion curve of the first optical lens in this disclosure is shown;

[0022] Figure 6 A schematic diagram of the optical structure of the second optical lens in this disclosure is shown;

[0023] Figure 7 The diffusion pattern of the second optical lens in this disclosure is shown;

[0024] Figure 8 The distortion curve of the second optical lens in this disclosure is shown;

[0025] Figure 9 A schematic diagram of the optical structure of the third optical lens in this disclosure is shown;

[0026] Figure 10 The diffusion pattern of the third optical lens in this disclosure is shown;

[0027] Figure 11 The distortion curve of the third optical lens in this disclosure is shown;

[0028] Figure 12 An exemplary structural diagram of an infrared vehicle-mounted lens according to some embodiments of this disclosure is shown. Detailed Implementation

[0029] The technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, not all of them. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0030] It should be understood that the terms “comprising” and “including” used in this disclosure and claims indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0031] It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this disclosure. As used in this disclosure and claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this disclosure and claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0032] As used in this specification and claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."

[0033] The specific embodiments disclosed herein will now be described in detail with reference to the accompanying drawings.

[0034] Exemplary application scenarios

[0035] Infrared imaging is a technique that uses infrared radiation to create images. This includes imaging by detecting the thermal radiation of natural objects and imaging by illuminating a target with an infrared light source and capturing the reflected infrared light. Infrared imaging technology is frequently used in the automotive industry, for example, in in-vehicle night vision systems to enhance driver vision at night or in low-visibility conditions, thereby improving driving safety.

[0036] Infrared imaging technology is often used in environments with poor lighting conditions, such as heavy fog, heavy rain, snow, and / or complete darkness. This places high demands on the performance of the optical lenses used for imaging. Especially in the automotive field, for safety reasons, infrared automotive night vision systems require optical lenses with excellent image quality to ensure that the detector can capture clear images.

[0037] Exemplary application scheme

[0038] In view of this, the present disclosure provides an optical lens solution that ensures that the optical lens can capture and retain as much light as possible and achieve a better aberration elimination effect by adjusting parameters such as the surface shape, optical power and arrangement of each optical lens in the optical lens, thereby achieving good image quality.

[0039] The following is combined Figure 1 and Figure 2 This section introduces the lens composition and optical parameters of optical lenses. Figure 1 An exemplary structural diagram of an optical lens according to some embodiments of this disclosure is shown. Figure 2 An exemplary structural diagram of an optical lens according to other embodiments of this disclosure is shown.

[0040] like Figure 1 and Figure 2 As shown in the embodiments disclosed herein, the optical lens may include a first lens 11, a second lens 12, and a third lens 13. The first lens 11 is designed with positive optical power; specifically, the first lens 11 may be a meniscus lens with positive optical power. During imaging, the convex surface of the first lens 11 is the light-receiving surface, that is, the object-side surface of the first lens 11 is convex. Designing the first lens 11 with positive optical power and a convex object-side surface ensures that more light enters the optical lens while also allowing the light to smoothly transition to the rear optical structure.

[0041] In this optical lens, the second lens 12 is designed with negative optical power; specifically, the second lens 12 can be a meniscus lens with negative optical power. During imaging, the convex surface of the second lens 12 also serves as the light-receiving surface, meaning the object-side surface of the second lens 12 is convex. When this optical lens is used for imaging, light enters the first lens 11 through its convex surface, exits through its concave surface, and re-enters through its convex surface. Designing the second lens 12 with negative optical power and using a convex object-side surface helps collect more light, while the concave image-side surface allows for a smooth transition of the outgoing light, thus facilitating the correction of light rays in different fields of view.

[0042] In this disclosed embodiment, the third lens 13 is designed with positive optical power, thereby forming an optical lens with a positive-negative-positive optical power design structure. The positive optical power of the third lens 13 facilitates light convergence and eliminates aberrations. In some embodiments, the third lens 13 can be as follows: Figure 1 The image shows a meniscus lens with positive optical power. In this case, the object-side surface of the third lens 13 is concave, meaning that when the optical lens is used for imaging, light enters the third lens 13 through its concave surface. In other embodiments, the third lens 13 may also be as follows... Figure 2 The image shows a biconvex lens, in which the object-side surface of the third lens 13 is convex.

[0043] In this disclosed embodiment, to meet the imaging requirements of practical application scenarios such as nighttime driving and autonomous driving, the first lens in the optical lens can be made of silicon. Silicon is a low-cost and high-hardness material, making it more suitable for assembly and use with heating elements.

[0044] In existing infrared automotive camera solutions, to avoid the effects of lens fogging, heating elements are typically incorporated into the optical lens for defogging. However, to prevent damage to the optical lens from the heating elements, a protective window is also required at the front of the lens, which increases both manufacturing costs and overall size.

[0045] The optical lens shown in this embodiment solves the problems of lens fogging, manufacturing cost, and lens miniaturization by using a first lens made of silicon. It can provide good protection for the optical lens while saving the cost and space occupied by the front protection window.

[0046] Furthermore, in some embodiments disclosed herein, a reasonable allocation of focal length is beneficial for further eliminating aberrations and reducing the risk of ghosting, thereby achieving good image quality. Based on this, the optical lens in the embodiments disclosed herein satisfies the following optical parameter conditions: 0.82≤|f1 / f|≤2.52, 0.66≤|f2 / f|≤2.20, and 0.57≤|f3 / f|≤0.70, where f1 represents the focal length of the first lens 11, f2 represents the focal length of the second lens 12, f3 represents the focal length of the third lens 13, and f represents the total focal length of the optical lens.

[0047] In practical applications, the light source environment for infrared imaging technology is often poor, such as heavy fog, heavy rain, snow, and / or pitch black night. This makes it difficult for the light source to provide enough infrared light for imaging.

[0048] To address the aforementioned issues, some embodiments disclosed herein eliminate aberrations by rationally allocating the focal length and improve the transmittance of the optical lens by designing the surface structure of the first lens 11. Specifically, the first lens 11 also satisfies the following condition: 0.23 ≤ |e1 / d1| ≤ 0.61, where e1 represents the edge distance of the first lens 11, which refers to the edge thickness of the lens, i.e., the distance from one side of the lens edge to the other side, and d1 represents the center thickness of the first lens 11. This edge distance to center thickness ratio design allows for thinning of the first lens 11 while also enabling the first lens 11 to have a reasonable degree of bending, thereby achieving better transmittance. The optical lens in this embodiment achieves good image quality from two aspects: aberration elimination and improved transmittance in the optical lens.

[0049] To further improve the performance of the optical lens, some embodiments disclosed herein further define the optical parameters of the optical lens. Specifically, this embodiment designs the radius of curvature of the first lens and the F-number of the entire optical lens, such that the optical lens satisfies the following condition: 1.00 ≤ f × ​​(n-1) / (FNO × R1) ≤ 2.55, where FNO represents the F-number of the optical lens, n represents the refractive index of the first lens, and R1 represents the radius of curvature of the object-side surface of the first lens.

[0050] The optical lenses described in the above embodiments can meet the transfer function requirements of uncooled detectors with a half-image height of 4.8 mm and below, for example, they are adapted to detectors with a resolution of 640*480_12μm.

[0051] In the process of light imaging, in addition to the effects of aberrations and transmittance on image quality, there are many other influencing factors, including but not limited to stray light and / or distortion.

[0052] In some embodiments, to reduce the field-of-view sensitivity of the central region, optimize the radius of curvature, and facilitate the elimination of stray light, the optical parameters of the optical lens may also satisfy the following condition: 0.95 ≤ |R1 / f| ≤ 2.51, where R1 represents the radius of curvature of the object-side surface of the first lens, and f represents the total focal length of the optical lens. It should be noted that R1 refers to the side of the first lens used to receive light. In the embodiments disclosed herein, the first lens is a meniscus lens with positive optical power and a convex surface as the object-side surface; therefore, R1 represents the radius of curvature of the convex surface of the first lens.

[0053] In some other embodiments, in order to ensure that the optical lens has a suitable field of view at a certain focal length, and has a good observation range and reasonable distortion, the optical parameters of the optical lens can also meet the following condition: 2.97≤|FOV / f|≤4.42, where FOV represents the horizontal field of view of the optical lens.

[0054] The above describes an embodiment of improving the imaging effect of an optical lens by adjusting various factors such as aberration, transmittance, stray light, and distortion. In practical applications, this optical lens is suitable for various in-vehicle functional units such as advanced driver assistance systems, autonomous driving systems, night vision systems, and driver monitoring systems. To facilitate the integration of the optical lens into the functional unit, it is necessary to miniaturize the optical lens for easier assembly.

[0055] In this embodiment, the miniaturization design of the optical lens can be divided into miniaturization designs in two directions: axial and radial. The axial miniaturization design can achieve the miniaturization of long focal length optical lenses, while the radial miniaturization design can reduce the volume of the optical lens by controlling the lens aperture.

[0056] For the purpose of axial miniaturization, the optical lenses of some embodiments disclosed herein need to satisfy one or more of the following conditions: 0.28≤|BFL / TTL|≤0.36 and 1.46≤|TTL / f|≤1.87, where BFL represents the distance from the image-side surface of the third lens to the image plane of the optical lens, and TTL represents the distance from the center of the object-side surface of the first lens to the imaging plane of the optical lens.

[0057] In the above conditions, |BFL / TTL| represents the ratio of the back focal length to the total optical length of the lens. Controlling this ratio allows for control of the back focal length ratio, which is beneficial for assembly. On one hand, adjusting the back focal length can alter the optical lens structure, shifting it from a semi-symmetrical to an asymmetrical design, which helps optimize the lens's imaging characteristics and reduce its size. On the other hand, controlling the back focal length plays a crucial role in achieving a shorter overall lens length; controlling the back focal length ratio facilitates a more compact optical system.

[0058] In the above conditions, |TTL / f| represents the ratio of the total optical length to the total focal length of the optical lens. Controlling this ratio allows for longer focal lengths and miniaturization of the optical lens. In optical design, this ratio reflects the compactness of the optical lens. A smaller ratio means a shorter total optical length relative to its focal length, providing greater focusing capability without requiring an excessively long lens tube, which better meets the expectations for telephoto lenses in practical applications. However, while a smaller ratio of total optical length to total focal length implies a more compact optical lens structure, it also places higher demands on optical performance and aberration correction. Therefore, it is necessary to control this ratio within a suitable range to achieve both telephoto capabilities and miniaturization while maintaining image quality.

[0059] Based on radial miniaturization considerations, the optical lenses of some embodiments disclosed herein must satisfy one or more of the following conditions: 1.20≤|D / ENPD|≤1.33 and 1.13≤|D1 / f|≤1.43, where D represents the maximum lens aperture in the optical lens, ENPD represents the entrance pupil diameter of the optical lens, and D1 represents the aperture of the first lens.

[0060] In the above conditions, |D / ENPD| is the ratio of the maximum aperture of the lens to the entrance pupil diameter. A smaller lens aperture is beneficial for reducing the size of the optical lens. |D1 / f| is the ratio of the aperture of the first lens to the total focal length of the optical lens. With the focal length unchanged, adjusting the value of D1 can reduce the front aperture of the optical lens, thereby reducing the size of the imaging system.

[0061] In addition to adjusting the structure of each lens in the optical lens, some embodiments disclosed herein also achieve cost reduction and miniaturization by adjusting the material selection of the optical lenses.

[0062] In some embodiments, the second lens in the optical lens is made of germanium glass or chalcogenide glass, and the third lens is made of chalcogenide glass. Chalcogenide glass is an amorphous material formed by combining chalcogen elements with other metallic elements. It has excellent mid- and far-infrared transmittance, making it well-suited for the needs of optical lenses used in the automotive field. Chalcogenide glass has a low temperature coefficient of refractive index, which allows for excellent anechoic optical properties, beneficial for thermal defocusing and chromatic aberration correction in infrared imaging systems. Furthermore, compared to traditional infrared materials, chalcogenide glass has lower raw material costs and higher processing efficiency, offering a significant cost advantage in mass production. Germanium glass, on the other hand, has a high refractive index and a wide infrared transmittance band. Its low absorption coefficient in the infrared band helps reduce absorption of incident light, improving infrared light transmission efficiency, making it well-suited for the needs of optical lenses used in the automotive field. Additionally, germanium glass maintains good transmittance at high temperatures, which is beneficial for imaging under harsh lighting conditions. Moreover, germanium glass has good processability, making its manufacturing process relatively easy and cost-effective.

[0063] Furthermore, the surface of the first lens can be set to be spherical, while the surfaces of the second and third lenses can be set to be aspherical. Specifically, the object-side and image-side surfaces of the first lens can be set to be spherical, the object-side and image-side surfaces of the second lens can be set to be aspherical, and the object-side and image-side surfaces of the third lens can be set to be aspherical.

[0064] For integrated scenarios such as advanced driver assistance systems, autonomous driving systems, night vision systems, and driver monitoring systems, lens fogging affects not only image quality but can also impact driving safety. To avoid the effects of lens fogging, existing solutions involve using heating elements to achieve a defogging effect. However, to prevent the heating elements from damaging the optical lens, a protective window needs to be installed at the front of the lens, which increases both manufacturing costs and lens size.

[0065] It should be noted that, in practical applications, a detector protection window 14 can also be provided on the image side of the third lens. During imaging, the incident light enters through the object side of the first lens 11, passes through the second lens 12, the third lens 13, and the detector protection window 14 in sequence, and finally converges on the imaging surface.

[0066] To address the issues posed by the front-end protection window, in some embodiments disclosed herein, the first lens in the optical lens is made of silicon. Silicon is a low-cost and high-hardness material, making it more suitable for assembly with heating elements. This provides good protection for the optical lens while saving on the cost and space occupied by the front-end protection window.

[0067] To more clearly illustrate the performance of the optical lenses provided in the embodiments disclosed herein, several exemplary optical lenses are provided below, and their specific numerical designs of optical parameters are shown for reference.

[0068] The following is a table of optical parameters for each lens in the first optical lens. Figure 3 A schematic diagram of the optical structure of the first optical lens in this disclosure is shown. Figure 3 As shown, in the first optical lens, the first lens is a meniscus convex lens with a convex object side, the second lens is a meniscus concave lens with a convex object side, and the third lens is a biconvex lens.

[0069]

[0070] The surface numbers in the table above are based on the order in which the light rays pass through the lens surfaces during imaging. S1 represents the convex surface of the first lens, S2 represents the concave surface of the first lens, S3 represents the convex surface of the second lens, and so on. S7 and S8 represent the detector protective windows, and IMA represents the image plane. A positive radius of curvature indicates that the surface bends towards the image plane, while a negative radius of curvature indicates that the surface bends towards the object plane. The spacing represents the central axial distance from the current surface to the next surface.

[0071] The following are the aspherical data for the first optical lens, where K is the conic coefficient and A to G are the coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspherical polynomial.

[0072]

[0073] The following is a supplementary table of optical parameters for the first optical lens.

[0074] Parameter type Value f / mm 13.4 FOV / ° 32 FNO 1 H / mm 4.8 TTL / mm 19.6 f×(n-1) / (FNO×R1) 2.55 BFL / TTL 0.28 D / ENPD 1.2 D1 / f 1.13

[0075] Figure 4 The diffusion pattern of the first optical lens in this disclosure is shown. Figure 5 The distortion curve of the first optical lens in this disclosure is shown. The blur pattern is represented by the root mean square radius value for each field of view, in μm. The distortion curve chart shows the distortion magnitude at different field angles, in %. Figure 4 It can be seen that the blur radius of the optical lens is small, the root mean square blur diameter varies little across different fields of view, and is all smaller than or approximately the pixel size resolved by the detector. From Figure 5 It is known that the system distortion of the optical lens is less than 1%. Based on the detector requirement of 640*480_12μm resolution, the various aberration requirements of the optical lens provided in this embodiment are all within the requirements.

[0076] The following is a table of optical parameters for each lens in the second optical lens. Figure 6 A schematic diagram of the optical structure of the second optical lens in this disclosure is shown. Figure 6 As shown, in the second optical lens, the first lens is a meniscus convex lens with a convex object side, the second lens is a meniscus concave lens with a convex object side, and the third lens is a meniscus convex lens with a concave object side.

[0077]

[0078] The surface numbers in the table above are based on the order in which the light rays pass through the lens surfaces during imaging. S1 represents the convex surface of the first lens, S2 represents the concave surface of the first lens, S3 represents the convex surface of the second lens, and so on. S7 and S8 represent the detector protective windows, and IMA represents the image plane. A positive radius of curvature indicates that the surface bends towards the image plane, while a negative radius of curvature indicates that the surface bends towards the object plane. The spacing represents the central axial distance from the current surface to the next surface.

[0079] The following are the aspherical data for the second optical lens, where K is the conic coefficient and A to G are the coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspherical polynomial.

[0080]

[0081] The following is a supplementary table of optical parameters for the second optical lens.

[0082] Parameter type Value f / mm 13.5 FOV / ° 32 FNO 1 H / mm 4.8 TTL / mm 25.3 f×(n-1) / (FNO×R1) 1.39 BFL / TTL 0.36 D / ENPD 1.33 D1 / f 1.33

[0083] Figure 7 The diffusion pattern of the second optical lens in this disclosure is shown. Figure 8 The distortion curves for the second optical lens in this disclosure are shown. The blur pattern is represented by the root mean square radius value for each field of view, in μm. The distortion curves also show the distortion magnitude at different field angles, in %. Figure 7 It can be seen that the blur radius of the optical lens is small, the root mean square blur diameter varies little across different fields of view, and is all smaller than or approximately the pixel size resolved by the detector. From Figure 8 It is known that the system distortion of the optical lens is less than 4%. Based on the detector requirement of 640*480_12μm resolution, all aberration requirements of the optical lens provided in this embodiment are within the specified limits.

[0084] The following is a table of optical parameters for each lens in the third optical lens. Figure 9 A schematic diagram of the optical structure of the third optical lens in this disclosure is shown. Figure 9 As shown, with Figure 3Similar to the first optical lens shown, in the third optical lens, the first lens is a meniscus convex lens with a convex object side, the second lens is a meniscus concave lens with a convex object side, and the third lens is a biconvex lens.

[0085]

[0086] The following are the aspherical data for the third optical lens, where K is the conic coefficient and A to G are the coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspherical polynomial.

[0087]

[0088]

[0089] The following is a supplementary table of optical parameters for the third optical lens.

[0090] Parameter type Value f / mm 9.1 FOV / ° 32 FNO 0.9 H / mm 3.2 TTL / mm 16.9 f×(n-1) / (FNO×R1) 1.08 BFL / TTL 0.31 D / ENPD 1.28 D1 / f 1.43

[0091] Figure 10 The diffusion pattern of the third optical lens in this disclosure is shown. Figure 11 The distortion curves for the third optical lens in this disclosure are shown. The blur pattern is represented by the root mean square radius value for each field of view, in μm. The distortion curves also show the distortion magnitude at different field angles, in %. Figure 10 It can be seen that the blur radius of the optical lens is small, the root mean square blur diameter varies little across different fields of view, and is all smaller than or approximately the pixel size resolved by the detector. From Figure 11 It is known that the system distortion of the optical lens is less than 5%. Based on the detector requirement of 640*480_12μm resolution, the various aberration requirements of the optical lens provided in this embodiment are all within the requirements.

[0092] By applying the optical lens from any of the preceding embodiments to the automotive field, an infrared vehicle-mounted lens can be obtained. Figure 12 Exemplary structural diagrams of infrared vehicle-mounted lenses according to some embodiments of this disclosure are shown, such as... Figure 12 As shown, the infrared vehicle-mounted lens includes a heating element 15 and an optical lens as described in any of the preceding embodiments. The heating element 15 is disposed on the image-side side of the first lens in the optical lens, i.e., between the first lens and the second lens, and is used to heat the optical lens to remove fog. Figure 12 As shown, the heat-conducting wire 151 on the heating element 15 can be located on one side of the optical system and extend to the circuit board. As an example, the heating element 15 can be a heating ring that surrounds the lens. In practical applications, the heating element can also take other forms that do not obstruct the propagation of light within the optical lens; no further restrictions are placed here.

[0093] In this optical lens, the convex surface of the first lens 11 faces the infrared light source to expand the range of infrared light received by the first lens, the convex surface of the second lens 12 faces the concave surface of the first lens to expand the range of infrared light emitted from the first lens received by the second lens, and the third lens 13 faces the concave surface of the second lens to converge the infrared light emitted from the concave surface of the second lens.

[0094] Furthermore, the first lens can be made of silicon. Silicon is a low-cost and high-hardness material, making it more suitable for assembly with heating elements. This provides better protection for the optical lens while saving the cost and space occupied by the front-end protection window.

[0095] Furthermore, in the aforementioned infrared vehicle-mounted lens, a heat insulation structure 16 can be attached behind the heating element 15. On one hand, the heat insulation structure 16 improves heating efficiency, enabling rapid heating and providing insulation; on the other hand, it reduces heat loss and acts as a barrier against heat dissipation. As an example, this heat insulation structure can be a foam insulation structure. Foam has excellent heat insulation properties, effectively preventing the heat generated by the heating element from being transferred to other components of the infrared vehicle-mounted lens. This prevents heat loss and effectively prevents damage to surrounding components due to excessive temperature. Moreover, foam can gently promote heat transfer, providing heat energy to clean the lens when the lens's field of view is obscured by ice, snow, or fog, while avoiding damage to the lens due to direct heating. Additionally, foam has excellent cushioning properties, absorbing stress caused by thermal expansion and contraction, thus providing cushioning and protecting the components in the infrared vehicle-mounted lens from mechanical impact.

[0096] It should be noted that the above description of the materials used in the thermal insulation structure is only an example. In practical applications, other materials can also be used for thermal insulation structures, such as polystyrene boards or polyester fibers. No further restrictions are imposed here.

[0097] To prevent the heat insulation structure from blocking the propagation of light inside the optical lens, the heat insulation structure can also be ring-shaped and attached to the rear of the heating ring. The rear corresponds to the direction of light transmission when the optical lens is used for imaging. In other words, the heat insulation structure can be set between the heating element and the second lens.

[0098] In practical use, a detector protection window can also be provided on the image side of the third lens. During imaging, the incident light enters through the object side of the first lens, and then passes through the second lens, the third lens and the detector protection window in sequence before finally converging on the imaging surface.

[0099] In some embodiments, the second lens in the optical lens is made of germanium glass or chalcogenide glass, and the third lens is made of chalcogenide glass. Chalcogenide glass is an amorphous material formed by combining chalcogen elements with other metallic elements. It has excellent mid- and far-infrared transmittance, making it well-suited for the needs of optical lenses used in the automotive field. Chalcogenide glass has a low temperature coefficient of refractive index, which allows for excellent anechoic optical properties, beneficial for thermal defocusing and chromatic aberration correction in infrared imaging systems. Furthermore, compared to traditional infrared materials, chalcogenide glass has lower raw material costs and higher processing efficiency, offering a significant cost advantage in mass production. Germanium glass, on the other hand, has a high refractive index and a wide infrared transmittance band. Its low absorption coefficient in the infrared band helps reduce absorption of incident light, improving infrared light transmission efficiency, making it well-suited for the needs of optical lenses used in the automotive field. Additionally, germanium glass maintains good transmittance at high temperatures, which is beneficial for imaging under harsh lighting conditions. Moreover, germanium glass has good processability, making its manufacturing process relatively easy and cost-effective.

[0100] To eliminate aberrations, improve transmittance, eliminate stray light, improve distortion, and / or reduce lens size, the optical lens in an infrared vehicle-mounted camera must meet at least one of the following conditions:

[0101] 0.82 ≤ |f1 / f| ≤ 2.52;

[0102] 0.66≤|f² / f|≤2.20;

[0103] 0.57≤|f³ / f|≤0.70;

[0104] 0.23≤|e1 / d1|≤0.61;

[0105] 1.00≤f×(n-1) / (FNO×R1)≤2.55;

[0106] 0.95≤|R1 / f|≤2.51;

[0107] 2.97 ≤ |FOV / f| ≤ 4.42;

[0108] 1.20≤|D / ENPD|≤1.33;

[0109] 1.13≤|D1 / f|≤1.43;

[0110] 0.28≤|BFL / TTL|≤0.36;

[0111] 1.46≤|TTL / f|≤1.87;

[0112] Where f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, f3 represents the focal length of the third lens, f represents the total focal length of the optical lens, e1 represents the edge distance of the first lens, d1 represents the center thickness of the first lens, FNO represents the F-number of the optical lens, n represents the refractive index of the first lens, R1 represents the radius of curvature of the object side of the first lens, FOV represents the horizontal field of view of the optical lens, D represents the maximum aperture of the optical lens, ENPD represents the entrance pupil diameter of the optical lens, D1 represents the aperture of the first lens, BFL represents the distance from the image side of the third lens to the image plane of the optical lens, and TTL represents the distance from the center of the object side of the first lens to the imaging plane of the optical lens.

[0113] In summary, the embodiments disclosed herein provide an optical lens that eliminates aberrations during imaging by designing parameters such as the surface shape, optical power, and arrangement of each optical lens, thereby achieving good image quality. Furthermore, the use of a silicon-based first lens allows the optical lens to be directly heated and defogging by a heating element, simplifying the protective structure in existing optical lenses and reducing cost and lens size.

[0114] Based on the optical lens provided in the embodiments disclosed herein, some embodiments of this disclosure further optimize the aberration elimination effect by reasonably allocating the focal lengths of each lens in the optical lens.

[0115] Based on the optical lenses provided in the embodiments disclosed herein, some embodiments of this disclosure further improve the transmittance of the optical lens by designing the surface structure of the first lens. By designing the ratio of edge distance to center thickness to thin the first lens, and simultaneously allowing the first lens to have a reasonable degree of bending, better transmittance is achieved. This enables the optical lens to achieve good image quality from both aberration elimination and improved transmittance aspects.

[0116] Based on the optical lenses provided in the embodiments disclosed herein, some embodiments of this disclosure further improve the imaging effect of the optical lenses by designing optical parameters in multiple aspects such as eliminating stray light and / or improving distortion.

[0117] In addition, some embodiments disclosed herein achieve miniaturization of the optical lens by controlling the ratio of the back focal length to the total optical length, the ratio of the total optical length to the total focal length, the ratio of the maximum aperture of the lens to the entrance pupil diameter, and / or the ratio of the aperture of the first lens to the total focal length of the optical lens.

[0118] Based on the optical lenses provided in this disclosure, some embodiments also provide infrared vehicle-mounted lenses suitable for the automotive field, which can enhance driver vision at night or in low visibility conditions and improve driving safety.

[0119] While numerous embodiments of this disclosure have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and intent of this disclosure. It should be understood that various alternatives to the embodiments of this disclosure described herein may be employed in the practice of this disclosure. The appended claims are intended to define the scope of this disclosure and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. An optical lens, characterized in that, include: The first lens (11) has positive optical power and is a meniscus lens with a convex object side. The first lens is made of silicon. The second lens (12) has negative optical power and is a meniscus lens with a convex object side. The third lens (13) has positive optical power and is either a biconvex lens or a meniscus lens with a concave object side. The optical lens is a vehicle-mounted infrared lens. The image side of the first lens in the optical lens, which is made of silicon, is provided with a heating element for heating the optical lens to remove fog. A heat insulation structure is attached behind the heating element.

2. The optical lens according to claim 1, characterized in that, The optical parameters of the first lens satisfy the following conditions: e1 represents the edge distance of the first lens, and d1 represents the center thickness of the first lens.

3. The optical lens according to claim 1, characterized in that, The optical parameters of the first lens satisfy the following conditions: , The second lens has the following optical parameters: The optical parameters of the third lens satisfy the following conditions: , This indicates the total focal length of the optical lens. This indicates the focal length of the first lens. This indicates the focal length of the second lens; This indicates the focal length of the third lens.

4. The optical lens according to claim 1, characterized in that, The optical parameters of the optical lens satisfy the following conditions: ； in, This indicates the F-number of the optical lens. This represents the refractive index of the first lens. This represents the radius of curvature of the object side surface of the first lens.

5. The optical lens according to claim 1, characterized in that, The optical parameters of the optical lens satisfy the following conditions: ； in, This represents the radius of curvature of the object side surface of the first lens.

6. The optical lens according to claim 1, characterized in that, The optical parameters of the optical lens satisfy the following conditions: ； in, This indicates the horizontal field of view of the optical lens.

7. The optical lens according to claim 1, characterized in that, The optical parameters of the optical lens satisfy one or more of the following conditions: ； ； in, This indicates the maximum lens aperture in the optical lens. This indicates the entrance pupil diameter of the optical lens. This indicates the aperture of the first lens.

8. The optical lens according to claim 1, characterized in that, The optical parameters of the optical lens satisfy one or more of the following conditions: ； ； in, This represents the distance from the image-side surface of the third lens to the image-side surface of the optical lens. This represents the distance from the center of the object side of the first lens to the imaging surface of the optical lens.

9. The optical lens according to claim 1, characterized in that, The second lens is made of germanium glass or chalcogenide glass, and the third lens is made of chalcogenide glass.

Images