A vehicle-mounted narrow-angle camera MTF test collimating lens
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHANGCHUN INST OF OPTICS FINE MECHANICS & PHYSICS CHINESE ACAD OF SCI
- Filing Date
- 2026-04-17
- Publication Date
- 2026-06-23
AI Technical Summary
In the current technology, the testing equipment for vehicle-mounted camera transmission functions needs to be imported from abroad, which leads to high costs for supporting equipment.
A collimating lens for MTF testing of a vehicle-mounted narrow-angle camera was designed, including a first lens, a second lens, and a third lens. It uses specific materials and optical parameters to meet the imaging requirements of the narrow-angle camera.
It provides an easy-to-assemble, low-cost, and highly efficient MTF testing solution for automotive narrow-angle cameras, meeting the imaging quality requirements of automotive narrow-angle lenses.
Smart Images
Figure CN122043708B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of optoelectronic testing instrument design technology, and in particular to a collimating lens for MTF testing of a vehicle-mounted narrow-angle camera. Background Technology
[0002] The MTF (Modulation Transfer Function) analyzer is used to evaluate the imaging performance of an optical system by analyzing its modulation transfer function (MTF), including on-axis and off-axis MTF values, and meridional and sagittal defocus MTF curves. The system can simultaneously measure parameters such as line spread function, phase transfer function, effective focal length, and distortion, and supports dynamic testing of both infinite and finite optical path systems.
[0003] Product models include:
[0004] Optest series: Standard benchtop equipment, weighing less than 200kg, equipped with OG-1000 light source and reflective collimator, suitable for batch inspection of visible light lenses;
[0005] LensCheck LWIR: Designed specifically for long-wave infrared optical lenses, it features a compact structure and integrates VideoMTF video imaging technology to enable real-time measurement.
[0006] Currently, all vehicle-mounted camera transmission testing equipment needs to be imported from abroad.
[0007] The core advantages of automotive narrow-angle lenses (typically with a field of view (FOV) of <40°, and some products as low as 20°~30°) are their long focal length, high-resolution imaging at long distances, and large depth of field. They can clearly capture details of distant objects and complement the "wide coverage" of fisheye lenses. They are the core component for achieving accurate long-distance perception in automotive camera systems.
[0008] Narrow-angle lenses are essential components for the accurate recognition of traffic signs at high speeds and long distances. Leveraging their advantages of long focal length and small field of view, they can clearly capture details of traffic signs such as speed limit signs, lane signs, and prohibitory signs at distances of more than 200 meters, providing accurate data for functions such as high-speed adaptive cruise control and traffic sign recognition, and ensuring the safety and intelligence of high-speed driving. Summary of the Invention
[0009] This invention aims to solve the technical problems of existing vehicle-mounted camera MTF testing equipment, such as the need for imports and high costs associated with supporting equipment, by providing a collimating lens for testing narrow-angle vehicle-mounted cameras.
[0010] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:
[0011] A collimating lens for MTF testing of a vehicle-mounted narrow-angle camera, comprising, in sequence along the optical path: a first lens, a second lens, and a third lens;
[0012] The object-side ray passes sequentially through the first lens incident surface and the first lens exit surface of the first lens, the second lens incident surface and the second lens exit surface of the second lens, and the third lens incident surface and the third lens exit surface of the third lens before reaching the image plane.
[0013] The center-to-center distance between the first and second lenses is 0.1 mm ± 0.01 mm; the center-to-center distance between the second and third lenses is 3.9 mm ± 0.01 mm.
[0014] The center thickness of the first lens is 6.0mm ± 0.05mm; the center thickness of the second lens is 4.0mm ± 0.05mm; the center thickness of the third lens is 4.0mm ± 0.05mm.
[0015] The radius of curvature of the incident surface of the first lens is 42.640±0.04mm, and the radius of curvature of the exit surface of the first lens is -40.039±0.04mm.
[0016] The radius of curvature of the incident surface of the second lens is -48.261±0.05mm, and the radius of curvature of the exit surface of the second lens is -46.067±0.05mm.
[0017] The radius of curvature of the incident surface of the third lens is -30.632±0.04mm, and the radius of curvature of the exit surface of the third lens is ∞mm.
[0018] In the above technical solution, the refractive index of the material of the first lens is 1.5666511680~1.5746320401, the refractive index of the material of the second lens is 1.9312155147~1.9839382871, and the refractive index of the material of the third lens is 1.6491819206~1.6657249034.
[0019] In the above technical solution, the material of the first lens is H-ZPK7, the material of the second lens is H-ZF88GT, and the material of the third lens is H-TF5.
[0020] In the above technical solution, the collimating lens operates in the wavelength range of 0.486µm to 0.656µm.
[0021] In the above technical solution, the entrance pupil diameter of the collimating lens is 5mm.
[0022] In the above technical solution, the field of view of the collimating lens is ±5°.
[0023] In the above technical solution, the object distance of the collimating lens is 112.0mm ± 0.1mm.
[0024] In the above technical solution, the image distance of the collimating lens is 81.479mm ± 0.1mm.
[0025] The present invention has the following beneficial effects:
[0026] The vehicle-mounted narrow-angle camera MTF testing collimating lens of the present invention adopts a narrow-angle collimating objective lens, which can provide a target at infinity during vehicle-mounted narrow-angle lens MTF testing.
[0027] The vehicle-mounted narrow-angle camera MTF testing collimating lens of the present invention has loose assembly and adjustment tolerances and large tolerance limits, and is easy to process and adjust; it has high testing efficiency and low processing cost. Attached Figure Description
[0028] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0029] Figure 1 This is a schematic diagram of the optical design of the collimating lens for MTF testing of the vehicle-mounted narrow-angle camera of the present invention.
[0030] Figure 2 This is a schematic diagram of the blur spot of the collimating lens for MTF testing of the vehicle-mounted narrow-angle camera of the present invention.
[0031] Figure 3 This is a schematic diagram of the field curvature and distortion of the collimating lens for MTF testing of the vehicle-mounted narrow-angle camera of the present invention.
[0032] Figure 4 This is a schematic diagram of the optical transfer function curve of the collimating lens for MTF testing of the vehicle-mounted narrow-angle camera of the present invention. In the figure, OTF on the vertical axis refers to the optical transfer function.
[0033] The reference numerals in the figure are as follows:
[0034] 1-First lens; 2-Second lens; 3-Third lens; 4-Aperture stop; 5-Image plane knife edge target;
[0035] S1 - Incident surface of the first lens; S2 - Exit surface of the first lens;
[0036] S3 - Incident surface of the second lens; S4 - Exit surface of the second lens;
[0037] S5 - Incident surface of the third lens; S6 - Exit surface of the third lens. Detailed Implementation
[0038] The inventive concept of this invention is as follows:
[0039] The vehicle-mounted narrow-angle camera MTF testing collimating lens of the present invention, based on aberration theory, uses the matching of positive and negative optical power of multiple lenses, appropriate lens materials, radius of curvature and spacing to correct field curvature, astigmatism, distortion, and magnification chromatic aberration. The imaging quality is close to the diffraction limit and can meet the usage requirements of optical transfer function measuring instruments.
[0040] The present invention will now be described in detail with reference to the accompanying drawings.
[0041] like Figure 1 As shown, the collimating lens for testing the MTF of the vehicle-mounted narrow-angle camera of the present invention comprises, from left to right: a first lens 1, a second lens 2, and a third lens 3; the aperture stop 4 is placed 112mm to the left of the first lens 1. During testing, the vehicle-mounted camera under test is placed at the aperture stop 4, and the image plane knife-edge target 5 is placed 81.479mm to the right of the last surface of the collimating lens (the right side of the third lens 3).
[0042] The vehicle-mounted narrow-angle camera MTF testing collimating lens of the present invention comprises, from left to right along the optical path propagation direction, the following components:
[0043] The left and right sides of the first lens 1: the first lens incident surface S1 and the first lens exit surface S2;
[0044] The left and right sides of the second lens 2: the incident surface S3 of the second lens and the exit surface S4 of the second lens;
[0045] The left and right sides of the third lens 3: the incident surface S5 and the exit surface S6 of the third lens.
[0046] in:
[0047] The radius of curvature of the incident surface S1 of the first lens is 42.640 mm, and the radius of curvature of the exit surface S2 of the first lens is -40.039 mm; the radius of curvature of the incident surface S3 of the second lens is -48.261 mm, and the radius of curvature of the exit surface S4 of the second lens is -46.067 mm; the radius of curvature of the incident surface S5 of the third lens is -30.632 mm, and the radius of curvature of the exit surface S6 of the third lens is ∞ mm, that is, the exit surface S6 of the third lens is a plane.
[0048] like Figure 1 As shown, light propagates from left to right. If the center of curvature of the radius of curvature is to the right of the vertex of the surface, the radius of curvature is positive. If the center of curvature of the radius of curvature is to the left of the vertex of the surface, the radius of curvature is negative. If the radius of curvature is ∞, then the surface is a plane.
[0049] As shown in Table 1, the object distance of the collimating lens for MTF testing of the vehicle-mounted narrow-angle camera of the present invention is 112.0 mm; the center interval between the first lens 1 and the second lens 2 is 0.1 mm; the center interval between the second lens 2 and the third lens 3 is 3.9 mm; and the center interval between the third lens 3 and the image plane is 81.479 mm, that is, the image distance is 81.479 mm.
[0050] The center thickness of the first lens 1 is 6.0 mm; the center thickness of the second lens 2 is 4.0 mm; and the center thickness of the third lens 3 is 4.0 mm.
[0051] The first lens 1 is a convex-convex positive lens made of H-ZPK7 material; the second lens 2 is a concave-convex positive lens made of H-ZF88GT material; and the third lens 3 is a concave-convex negative lens made of H-TF5 material.
[0052] Table 1 Optical Component Parameter Table
[0053]
[0054] The optical parameters of the collimating lens for MTF testing of the vehicle-mounted narrow-angle camera of the present invention are as follows:
[0055] Focal length: 102mm, operating wavelength: 0.486µm~0.656µm, entrance pupil diameter: 5mm, object distance: 112.0mm, image distance: 81.479mm.
[0056] The collimating lens for MTF testing of the vehicle-mounted narrow-angle camera of the present invention is a visible light band lens that emits visible light from a knife-edge target. When applied to an optical transfer function measuring instrument, it is used to test the imaging quality of the vehicle-mounted narrow-angle camera.
[0057] Depend on Figure 2 As can be seen from the blur pattern shown, the blur pattern in each field of view of the collimating lens system of the present invention is well corrected, and the blur pattern radius is within the Airy disk. The RMS value of the on-axis blur pattern radius is 0.268µm, and the RMS value of the blur pattern radius at the maximum off-axis field of view is 3.765µm.
[0058] Depend on Figure 3 As shown in the field curvature and distortion diagrams, the maximum field curvature of the collimating lens system of the present invention is 0.2 mm, and the maximum distortion is 0.89%.
[0059] Depend on Figure 4 As can be seen from the optical transfer function curves shown, the optical transfer function of the collimating lens system of the present invention is close to the diffraction limit in each field of view.
[0060] In summary, the imaging quality of the collimating lens for testing the MTF of the vehicle-mounted narrow-angle camera of the present invention can meet the requirements of the optical transfer function measuring instrument and can be used to test the imaging quality of the vehicle-mounted narrow-angle camera.
[0061] The vehicle-mounted narrow-angle camera MTF testing collimating lens of the present invention adopts a narrow-angle collimating objective lens, which can provide a target at infinity during vehicle-mounted narrow-angle lens MTF testing.
[0062] The vehicle-mounted narrow-angle camera MTF testing collimating lens of the present invention has loose assembly and adjustment tolerances and large tolerance limits, and is easy to process and adjust; it has high testing efficiency and low processing cost.
[0063] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A collimating lens for MTF testing of a vehicle-mounted narrow-angle camera, characterized in that, The optical path includes, in sequence: a first lens (1), a second lens (2), and a third lens (3); The object-side light rays pass sequentially through the first lens incident surface (S1) and the first lens exit surface (S2) of the first lens (1), the second lens incident surface (S3) and the second lens exit surface (S4) of the second lens (2), and the third lens incident surface (S5) and the third lens exit surface (S6) of the third lens (3) before reaching the image plane. The center-to-center distance between the first lens (1) and the second lens (2) is 0.1 mm ± 0.01 mm; the center-to-center distance between the second lens (2) and the third lens (3) is 3.9 mm ± 0.01 mm. The center thickness of the first lens (1) is 6.0mm ± 0.05mm; the center thickness of the second lens (2) is 4.0mm ± 0.05mm; the center thickness of the third lens (3) is 4.0mm ± 0.05mm. The radius of curvature of the incident surface (S1) of the first lens is 42.640±0.04mm, and the radius of curvature of the exit surface (S2) of the first lens is -40.039±0.04mm. The radius of curvature of the incident surface (S3) of the second lens is -48.261±0.05mm, and the radius of curvature of the exit surface (S4) of the second lens is -46.067±0.05mm. The radius of curvature of the incident surface (S5) of the third lens is -30.632±0.04mm, and the radius of curvature of the exit surface (S6) of the third lens is ∞mm.
2. The vehicle-mounted narrow-angle camera MTF testing collimating lens according to claim 1, characterized in that, The refractive index of the material of the first lens (1) is 1.5666511680~1.5746320401, the refractive index of the material of the second lens (2) is 1.9312155147~1.9839382871, and the refractive index of the material of the third lens (3) is 1.6491819206~1.6657249034.
3. The vehicle-mounted narrow-angle camera MTF testing collimating lens according to claim 2, characterized in that, The material of the first lens (1) is H-ZPK7, the material of the second lens (2) is H-ZF88GT, and the material of the third lens (3) is H-TF5.
4. The vehicle-mounted narrow-angle camera MTF testing collimating lens according to claim 1, characterized in that, The collimating lens operates in the wavelength range of 0.486µm to 0.656µm.
5. The vehicle-mounted narrow-angle camera MTF testing collimating lens according to claim 1, characterized in that, The entrance pupil diameter of this collimating lens is 5mm.
6. The vehicle-mounted narrow-angle camera MTF testing collimating lens according to claim 1, characterized in that, The collimating lens has a field of view of ±5°.
7. The vehicle-mounted narrow-angle camera MTF testing collimating lens according to claim 1, characterized in that, The object distance of the collimating lens is 112.0mm ± 0.1mm.
8. The vehicle-mounted narrow-angle camera MTF testing collimating lens according to claim 1, characterized in that, The image distance of the collimating lens is 81.479mm ± 0.1mm.