Vehicle-mounted long-wave infrared imaging lens, camera module and optical system

Abstract

The invention relates to a vehicle-mounted long-wave infrared imaging lens based on refraction and super hybrid design, a camera module and an optical system. The vehicle-mounted long-wave infrared imaging lens comprises a first lens, a second lens and a third lens which are sequentially arranged from an object plane to an image plane along an optical axis. According to the vehicle-mounted infrared lens, a folding and super hybrid design scheme is adopted, the first lens and the third lens are aspheric lenses, and the second lens is a super-surface lens, so that the problems that the weight of a traditional vehicle-mounted infrared lens exceeds the limit and the axial size is too large are solved. In addition, according to the scheme, the complexity of the system is reduced, the cost is reduced, the reliability is improved, and performance degradation is not prone to occurring in the temperature change environment. Meanwhile, the system has achromatic imaging capability, can meet the application in a complex illumination environment, achieves high-resolution imaging, and meets the use requirements of vehicle-gauge-level imaging.

Description

Technical Field

[0001] This invention belongs to the field of optical lenses, specifically relating to an automotive long-wave infrared imaging lens, camera module, and optical system based on a hybrid design of refractive and hyper-refractive elements, suitable for automotive-grade environmental perception and intelligent driving scenarios. Background Technology

[0002] Automotive-grade long-wave infrared (8-14μm) imaging technology enables object recognition and distance perception in nighttime and low-visibility environments by detecting the thermal radiation of targets. Its optical system needs to maintain high thermal sensitivity under extreme temperature conditions (-40℃~105℃) while meeting the requirements of shock resistance, miniaturization and cost control.

[0003] Metasurfaces are two-dimensional planar optical materials composed of periodically arranged artificial micro / nano structures at the submicron scale. Compared to traditional refractive optical elements, metasurfaces can be mass-produced using micro / nano fabrication techniques such as photolithography and nanoimprinting, offering significant advantages in manufacturing cost and process complexity. By optimizing parameters such as the configuration and arrangement period of their micro / nano structural units, the phase distribution and propagation path of incident light waves can be precisely controlled, thereby achieving efficient light field modulation and imaging functions in the infrared band.

[0004] In hybrid optical systems, the innovative value of metasurface technology is reflected in the integration of optical functions and the improvement of system performance: First, its sub-millimeter thickness characteristics break through the spatial limitations of the traditional filter-imaging separation architecture, reducing the thickness of the optical module; Second, through customized design of metasurface nanostructures, narrowband spectral filtering, off-axis aberration correction and speckle suppression can be completed in a single-layer element, significantly improving the signal-to-noise ratio of biological features in complex lighting scenarios (such as strong backlight and multi-source interference).

[0005] Traditional germanium-based refractive indexing schemes face significant bottlenecks in improving optical efficiency, suppressing thermal drift, and achieving lightweight design, thus limiting the all-weather perception reliability of intelligent driving systems. Compared to traditional multi-chip infrared imaging systems, the hybrid refractive-hyper-refractive indexing design effectively reduces optical crosstalk and system power consumption. This technology is expected to achieve breakthroughs in areas such as wide dynamic range response and multi-band spectral fusion, and is expected to deliver superior performance in scenarios such as resistance to environmental thermal interference (e.g., road surface radiation) and dynamic field-of-view switching. Summary of the Invention

[0006] This invention provides a vehicle-mounted long-wave infrared imaging lens, camera module, and optical system based on a hybrid design of refractive and hyper-refractive elements. While ensuring focal length and F-number, it reduces the number of lenses, TTL (total optical length), volume, and cost, thereby achieving high-resolution imaging.

[0007] This invention provides a vehicle-mounted long-wave infrared imaging lens based on a hybrid refractive-hyper-optical design. The lens includes a first lens, a second lens, and a third lens arranged sequentially along the optical axis from the object plane to the image plane.

[0008] The first lens is an aspherical lens with negative optical power. Its object side is concave, and its image side is concave in the near-optical axis region and convex in the edge region. Both the object side and the image side of the first lens are aspherical.

[0009] The second lens is a metasurface lens with positive optical power. The metasurface lens includes a substrate and a micro / nano structure disposed on the substrate. The object side and the image side of the second lens are both planar, and the image side has a micro / nano structure.

[0010] The third lens is an aspherical lens with positive optical power, its object side is convex and its image side is concave, and both the object side and image side of the third lens are aspherical.

[0011] Furthermore, the vehicle-mounted long-wave infrared imaging lens also includes a fourth lens, which is a protective glass and is located after the third lens.

[0012] Optionally, the vehicle-mounted long-wave infrared imaging lens satisfies:

[0013]

[0014] Where Fno is the aperture number, EFL is the focal length, TTL is the distance from the center of the optical axis on the object side of the first lens to the image plane, and FOV is the diagonal field of view.

[0015] Optionally, the vehicle-mounted long-wave infrared imaging lens satisfies:

[0016]

[0017] Optionally, the vehicle-mounted long-wave infrared imaging lens further includes an aperture stop; the aperture stop is located in front of the first lens, or the aperture stop is located in the optical path between the first lens and the second lens, or the aperture stop is located in the optical path between the second lens and the third lens.

[0018] Furthermore, the aperture stop is located in front of the first lens.

[0019] Optionally, the focal length of the vehicle-mounted long-wave infrared imaging lens satisfies f≥6.9mm.

[0020] Optionally, the field of view of the vehicle-mounted long-wave infrared imaging lens satisfies FOV≥56°.

[0021] Optionally, the operating temperature of the vehicle-mounted long-wave infrared imaging lens is -40℃ to 80℃.

[0022] The present invention also provides a camera module, which includes the above-mentioned vehicle-mounted long-wave infrared imaging lens.

[0023] The present invention also provides an optical system comprising the above-described camera module, suitable for automotive-grade long-wave infrared high-resolution imaging scenarios.

[0024] This invention provides a vehicle-mounted long-wave infrared imaging lens based on a hybrid refractive-hypersurface design, employing only four lenses: two aspherical lenses, one metasurface lens, and one protective glass lens. Its simple structure, small size, and cost-effective manufacturing process, while maintaining a stable operating temperature range (-40℃ to 80℃), are achieved through the use of a second metasurface lens with optimized phase distribution. The hybrid design of the folding and super-folding long-wave infrared imaging lens for vehicles ensures a compact overall optical length with a focal length of f≥6.9mm in the central region; the overall field of view of the hybrid design of the folding and super-folding long-wave infrared imaging lens for vehicles is greater than or equal to 56°, which is suitable for the needs of vehicle environmental perception.

[0025] This invention solves the problems of large size, many lenses, and long optical length in the existing technology, and improves the response rate and resolution of the imaging system, realizing automotive-grade long-wave infrared high-resolution imaging. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a vehicle-mounted long-wave infrared imaging lens based on a folding-hybrid design provided in an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the MTF of a vehicle-mounted long-wave infrared imaging lens based on a folding-hybrid design provided in an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the blur pattern of a vehicle-mounted long-wave infrared imaging lens based on a folding-hybrid design, provided in an embodiment of the present invention.

[0029] Figure 4 This is a relative illumination diagram of a vehicle-mounted long-wave infrared imaging lens based on a refracto-hybrid design, provided in an embodiment of the present invention.

[0030] Explanation of reference numerals in the attached figures:

[0031] 100, Aperture stop; 110, First lens; 120, Second lens; 130, Third lens; 140, Fourth lens; 150, Imaging plane. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings.

[0033] The vehicle-mounted long-wave infrared imaging lens provided in this embodiment of the invention includes a first lens 110, a second lens 120, and a third lens 130 arranged sequentially along the optical axis from the object plane to the image plane. The first lens 110 is an aspherical lens with negative optical power, its object-side surface is concave, its image-side surface is concave in the near-optical axis region and convex in the edge region, and both the object-side surface and the image-side surface of the first lens 110 are aspherical. The second lens 120 is a metasurface lens with positive optical power, the metasurface lens including a substrate and a micro / nano structure disposed on the substrate; both the object-side surface and the image-side surface of the second lens 120 are planar, and its image-side surface has a micro / nano structure. The third lens 130 is an aspherical lens with positive optical power, its object-side surface is convex, its image-side surface is concave, and both the object-side surface and the image-side surface of the third lens 130 are aspherical.

[0034] This design enables the vehicle-mounted long-wave infrared imaging lens to have chromatic aberration reduction capabilities, thus ensuring that the imaging quality remains unchanged within a certain range.

[0035] In addition, to protect the sensor, the vehicle-mounted long-wave infrared imaging lens also includes a fourth lens 140. In this invention, the fourth lens 140 is configured as a protective glass, which is fixed in front of the image sensor, and the detector can be placed at the imaging surface 150.

[0036] The protective glass is preferably made of optical glass with a refractive index of 250 and an Abbe number of 3.418. Its main function is to provide a physical barrier for the image sensor while ensuring high transmittance, effectively blocking the intrusion of dust and particles, and resisting a certain degree of mechanical impact or scratches, significantly reducing the risk of sensor damage and ensuring stable image quality.

[0037] In this invention, the second lens 120 consists of a substrate and micro / nano structures disposed on the substrate. These micro / nano structures are composed of subwavelength-scale micro / nano unit arrays, each with a specific shape, size, and arrangement to achieve precise control over the phase, amplitude, or polarization state of the incident light wave. Through the design of these micro / nano structures, the metasurface lens can achieve optical performance comparable to or even superior to traditional lenses while maintaining a thin and light volume, such as high transmittance, low chromatic aberration, and low distortion. The period of the micro / nano structures in the second lens ranges from 1.5 to 3.5 μm, with an optimal period of 3 μm in this invention; the height of the micro / nano structures ranges from 5 to 15 μm, with an optimal height of 10 μm in this invention; the diameter of the micro / nano structures covers 1 to 2.5 μm, the material is silicon, and they are arranged in square, hexagonal, or other shapes.

[0038] As a feasible implementation method, the first lens 110 and the third lens 130 are made of chalcogenide glass, while the second lens 120 and the fourth lens 140 are made of glass. By matching the materials and the optical power of each lens, a heatless design is achieved, which reduces material costs, shrinks the system size, and ensures the operating temperature range.

[0039] In addition, in order to control the path of light through the lens and reduce stray light interference, thereby improving image quality, the vehicle-mounted long-wave infrared imaging lens also includes an aperture stop 100.

[0040] The aperture stop 100 can be located in front of the first lens 110, or in the optical path between the first lens 110 and the second lens 120, or in the optical path between the second lens 120 and the third lens 130. Preferably, in this embodiment, the aperture stop 100 is selected to be located in front of the first lens 110 according to actual needs, so as to more precisely control the light passing through the aperture and achieve the best imaging effect.

[0041] Based on the above solutions, the vehicle-mounted long-wave infrared imaging lens meets the requirements. With a focal length f≥6.9mm in the central region, a compact overall optical length is ensured; the overall field of view of the vehicle-mounted long-wave infrared imaging lens is greater than or equal to 56°, adapting to the usage requirements of vehicle-mounted environmental perception. In this embodiment, the lens operates at a temperature of -40℃~80℃, exhibiting high reliability and stability.

[0042] Example

[0043] Table 1 shows the parameters of a vehicle-mounted long-wave infrared imaging lens based on a folding-hybrid design provided in the embodiment.

[0044] Table 1

[0045]

[0046] Wherein, BFL is the axial distance from the vertex of the last optical surface in the optical system to the image-side focal point (focal plane) of the system.

[0047] refer to Figure 1 The vehicle-mounted long-wave infrared imaging lens provided in this embodiment of the invention includes an aperture stop 100, a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, and an imaging plane 150 arranged sequentially along the optical axis from the object plane to the image plane.

[0048] The first lens 110 is an aspherical lens with negative optical power, its object-side surface is concave, its image-side surface is concave in the near-optical axis region and convex in the edge region, and both the object-side and image-side surfaces of the first lens 110 are aspherical; the second lens 120 is a metasurface lens with positive optical power, the metasurface lens includes a substrate and micro / nano structures disposed on the substrate; both the object-side and image-side surfaces of the first lens 120 are planar, and its image-side surface has micro / nano structures; the third lens 130 is an aspherical lens with positive optical power, its object-side surface is convex, and its image-side surface is concave, and both the object-side and image-side surfaces of the third lens 130 are aspherical; the fourth lens 140 is a protective glass that protects the sensor.

[0049] like Figure 1 As shown, the incident light enters through the aperture 100, and after passing through the first lens 110, the second lens 120, the third lens 130 and the fourth lens 140, it converges on the imaging surface 150.

[0050] Table 2 shows the parameters of each surface in the vehicle-mounted long-wave infrared imaging lens provided in the embodiment.

[0051] Table 2

[0052]

[0053] The surface numbering is based on the order of the lenses' surfaces. For example, surface number 1 represents the object-side surface of the first lens 110, surface number 2 represents the image-side surface of the first lens 110, and so on, until surface number 10 represents the imaging surface 150. The radius of curvature represents the degree of curvature of the lens surface; a positive value indicates that the surface bends towards the image plane, and a negative value indicates that the surface bends towards the object plane. "Infinity" indicates that the surface is planar, "Extended Odd Asphere" indicates an extended odd-order aspherical surface, and "Metasurface" indicates a binary surface. The spacing represents the central axial distance from the current surface to the next surface. Both the radius of curvature and the spacing are in millimeters (mm).

[0054] Even-order aspherical surfaces satisfy the following equations:

[0055]

[0056] Where z is the distance from the even-order aspherical surface to its vertex along the optical axis, r is the height from the optical axis, c is the curvature 1 / R, and R is the radius of curvature at the vertex of the lens; N is the number of polynomial coefficients in the series, k is the conic coefficient, and a i For aspherical higher-order terms, the coefficients are given.

[0057] For example, Table 3 details the conic coefficient k and higher-order coefficient a of the aspherical lens surface in this embodiment, using a feasible implementation method.i .

[0058] Table 3

[0059] Face number k R1 <![CDATA[a2]]> <![CDATA[a3]]> <![CDATA[a4]]> <![CDATA[a5]]> 1 17.249 0 -1.225E-3 -1E-5 1.99E-6 4.75E-7 2 -85.37 0 -1.661E-3 2.329E-5 -1.223E-7 4.373E-9 5 -5.926 0 6.464E-4 -9.064E-8 3.157E-7 1.655E-8 6 91.873 0 1.448E-3 1.5E-5 1.116E-6 -1.248E-7

[0060]

[0061]

[0062] Where R1 is the normalized radius of the binary surface, -1.225E-3 means that the coefficient a2 of surface number 1 is -0.001225, and so on.

[0063] For example, Table 4 details the phase of the metasurface in this embodiment with a feasible implementation.

[0064] Table 4

[0065]

[0066] The vehicle-mounted long-wave infrared imaging lens provided in this embodiment operates in the long-wave infrared band, with an Fno of 0.83, a focal length of 7.3mm, and a full field of view of 56°.

[0067] Figure 2 The modulation function curves of the vehicle-mounted long-wave infrared imaging lens provided in this embodiment of the invention are shown. Different colored curves represent different fields of view. The higher the value of the curve, the larger the blank area below the curve, and the smoother the curve, the better the image quality and the clearer the imaging. The vehicle-mounted long-wave infrared imaging lens provided in this embodiment of the invention has an edge field of view modulation function curve value greater than 20% at a frequency of 63 line pairs per millimeter, which has excellent imaging effect and can meet the optical imaging requirements of high resolution and high image quality.

[0068] Figure 3 This is a schematic diagram of the blur pattern of the vehicle-mounted long-wave infrared imaging lens provided in an embodiment of the present invention. The vehicle-mounted long-wave infrared imaging lens provided in this embodiment of the present invention has a relatively concentrated and uniformly distributed blur pattern throughout the long-wavelength band, which can meet the requirements of high-resolution imaging.

[0069] Figure 4 This is a schematic diagram of the relative illumination of a vehicle-mounted long-wave infrared imaging lens provided in an embodiment of the present invention, which represents the relative illumination values ​​corresponding to different fields of view, such as... Figure 4 As shown, the vehicle-mounted long-wave infrared imaging lens provided in this embodiment of the invention has an edge field of view relative illumination of over 40% in the working band, which meets the requirements of most usage scenarios.

[0070] The present invention also provides a camera module, which includes the above-mentioned vehicle-mounted long-wave infrared imaging lens.

[0071] The present invention also provides an optical system comprising the above-described camera module, suitable for automotive-grade long-wave infrared high-resolution imaging scenarios.

[0072] In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application 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. Therefore, they should not be construed as limitations on this application.

[0073] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A vehicle-mounted long-wave infrared imaging lens based on a folded superhybrid design, characterized in that, Comprise: a first lens, a second lens and a third lens are sequentially arranged from an object plane to an image plane along an optical axis; the first lens is an aspherical lens with negative focal power, the object side surface of the first lens is a concave surface, the image side surface of the first lens is a concave surface in the near optical axis region and a convex surface in the edge region, and the object side surface and the image side surface of the first lens are both aspherical surfaces; the second lens is a metasurface lens with positive focal power, the metasurface lens comprises a substrate and a micro-nano structure arranged on the substrate, and the object side surface and the image side surface of the second lens are both flat surfaces, and the image side surface of the second lens has a micro-nano structure; the third lens is an aspherical lens with positive focal power, the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface, and the object side surface and the image side surface of the third lens are both aspherical surfaces.

2. The vehicle-mounted long-wave infrared imaging lens according to claim 1, characterized in that, Further comprising a fourth lens, the fourth lens is a protective glass arranged after the third lens.

3. The vehicular long-wave infrared imaging lens of claim 1, wherein, The vehicle-mounted long-wave infrared imaging lens satisfies: wherein Fno is the aperture number, EFL is the focal length, TTL is the distance from the optical axis center of the object side surface of the first lens to the image plane, and FOV is the diagonal field of view.

4. The vehicular long-wave infrared imaging lens of claim 1, wherein, The vehicle-mounted long-wave infrared imaging lens satisfies:

5. The vehicular long-wave infrared imaging lens of claim 1, wherein, The vehicle-mounted long-wave infrared imaging lens further comprises a diaphragm; the diaphragm is located before the first lens, or the diaphragm is located in the optical path between the first lens and the second lens, or the diaphragm is located in the optical path between the second lens and the third lens.

6. The vehicular long-wave infrared imaging lens of claim 5, wherein, The diaphragm is located before the first lens.

7. The vehicular long-wave infrared imaging lens of claim 1, wherein, The focal length f of the vehicle-mounted long-wave infrared imaging lens satisfies: f≥6.9mm.

8. The vehicular long-wave infrared imaging lens of claim 1, wherein, The field of view FOV of the vehicle-mounted long-wave infrared imaging lens satisfies: FOV≥56°.

9. The vehicular long-wave infrared imaging lens of claim 1, wherein, The working temperature of the vehicle-mounted long-wave infrared imaging lens is -40℃-80℃.

10. An image capture module, comprising: Comprise the vehicle-mounted long-wave infrared imaging lens as claimed in claims 1-9.

11. An optical system characterized by comprising: Comprise the camera module as claimed in claim 10.

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