Large-aperture and large-depth-of-field short-wave infrared vehicle-mounted lens

Abstract

The application discloses a large-aperture large-depth-of-field short-wave infrared vehicle-mounted lens, which is applied to a short-wave infrared spectrum and comprises, in sequence from an object plane to an image plane, a lens L1 with negative optical power, a lens L2 with negative optical power, a lens L3 with positive optical power, a diaphragm STOP, a lens L4 with negative optical power, a lens L5 with positive optical power, a lens L6 with positive optical power and a lens L7 with positive optical power, wherein the total optical length TTL, the effective aperture D and the total focal length f of the vehicle-mounted lens satisfy 1.4 <= f / D <= 1.8 and 0.1 <= f / TTL <= 0.2. The vehicle-mounted lens adopts a large-aperture large-depth-of-field design, is more suitable for a long-distance, large-range and low-illumination environment, and can clearly image in a range of 0.75 m to infinity without re-focusing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle-mounted lenses, in particular to a large-aperture large-DOF short-wave infrared vehicle-mounted lens. BACKGROUND

[0002] The existing vehicle-mounted lenses not only need to provide clear and accurate road image information, but also need to ensure the driving safety of the vehicle at night or in severe weather such as thunderstorms, fog and haze. As one of the "atmospheric transmission windows", short-wave infrared has the advantages of small atmospheric scattering, strong fog, haze and smoke dust penetration, and long effective detection distance, and its adaptability to climate conditions and environment is obviously better than that of visible light imaging. This makes the short-wave infrared imaging have a significant innate advantage when applied to vehicle-mounted lenses.

[0003] However, the current vehicle-mounted lenses are mostly in the visible light or near-infrared working spectrum, which cannot meet the application requirements of short-wave infrared imaging. Moreover, the existing vehicle-mounted lenses are often designed for specific distance targets, and the depth of field and field of view cannot be achieved simultaneously, which is difficult to meet the observation requirements of large-range and large-DOF targets in front of the vehicle during high-speed driving. SUMMARY

[0004] The purpose of the present application is to provide a large-aperture large-DOF short-wave infrared vehicle-mounted lens with a large observation range and a long detection distance.

[0005] Technical scheme: To achieve the above purpose, the large-aperture large-DOF short-wave infrared vehicle-mounted lens of the present application is applied in the 1300-1350nm short-wave infrared spectrum, and includes lenses L1, L2, L3, STOP, L4, L5, L6 and L7 with negative, negative, positive, positive, negative, positive and positive optical powers, respectively, arranged in order from the object plane to the image plane. The optical total length TTL, effective aperture D and total focal length f of the vehicle-mounted lens satisfy 1.4≤f / D≤1.8 and 0.1≤f / TTL≤0.2.

[0006] Among them, the object side surface of the lens L1 is convex, and the image side surface is concave; the object side surface of the lens L2 is convex, and the image side surface is concave; the object side surface of the lens L3 is convex, and the image side surface is convex; the object side surface of the lens L4 is convex, and the image side surface is concave; the object side surface of the lens L5 is concave, and the image side surface is convex; the object side surface of the lens L6 is convex, and the image side surface is convex; the object side surface of the lens L7 is convex, and the image side surface is convex.

[0007] The refractive index of the lens L1 is 1.78 <= Nd1 <= 1.84, and the Abbe number is 42 <= Vd1 <= 50; the refractive index of the lens L2 is 1.57 <= Nd2 <= 1.63, and the Abbe number is 55 <= Vd2 <= 65; the refractive index of the lens L3 is 1.80 <= Nd3 <= 1.92, and the Abbe number is 35 <= Vd3 <= 42; the refractive index of the lens L4 is 1.90 <= Nd4 <= 1.95, and the Abbe number is 15 <= Vd4 <= 23; the refractive index of the lens L5 is 1.80 <= Nd5 <= 1.92, and the Abbe number is 35 <= Vd5 <= 42; the refractive index of the lens L6 is 1.80 <= Nd6 <= 1.85, and the Abbe number is 38 <= Vd6 <= 48; and the refractive index of the lens L7 is 1.48 <= Nd7 <= 1.63, and the Abbe number is 61 <= Vd7 <= 72.

[0008] The focal length of the lens L1 is -12 <= f1 <= 8; the focal length of the lens L2 is -50 <= f2 <= -35; the focal length of the lens L3 is 13 <= f3 <= 19; the focal length of the lens L4 is -45 <= f4 <= -32; the focal length of the lens L5 is 15 <= f5 <= 25; the focal length of the lens L6 is 12 <= f6 <= 23; and the focal length of the lens L7 is 30 <= f7 <= 47.

[0009] The total length TTL of the vehicle-mounted lens and the distance BFL between the center of the seventh lens image side surface and the image surface satisfy: TTL / BFL <= 5.

[0010] The total focal length f of the vehicle-mounted lens and the distance BFL between the center of the seventh lens image side surface and the image surface satisfy: 0.5 <= f / BFL <= 1.

[0011] The field of view of the vehicle-mounted lens is FOV = 0°~108°.

[0012] The effective imaging object distance of the vehicle-mounted lens is 0.75m to infinity without refocusing.

[0013] The lenses L1 to L7 are all glass spherical single lenses.

[0014] A filter is further arranged between the lens L7 and the image surface.

[0015] Beneficial effects: Compared with the prior art, the present application has the following obvious advantages:

[0016] 1. The vehicle-mounted lens works in the short-wave infrared spectrum, the spectrum range is 1300-1350nm, which is different from the traditional near-infrared imaging, the lens in this spectrum has strong fog, rain, snow and dust ability, and the effective detection distance is far;

[0017] 2. The vehicle-mounted lens of the present invention adopts a large aperture and large field of view design, with an aperture number FNO = 1.6 and a field of view angle FOV = 108°; it is suitable for a wide range of low-light environments. At the same time, compared with existing lenses, this vehicle-mounted lens has an extremely large depth of field. Without refocusing, it can clearly image the object distance from 0.75m to infinity, ensuring that objects at different levels can obtain clear images and details;

[0018] 3. The vehicle-mounted lens of the present invention utilizes seven lenses with specific optical powers. Through reasonable layout and distribution of optical powers, light aberration is reduced and lens resolution is improved. At the same time, the total optical length of the lens does not exceed 35mm, and the structure is compact, which is conducive to vehicle integration.

[0019] 4. The lenses of this vehicle-mounted lens are all glass spherical single lenses, without cemented lenses. This avoids the shortcomings of cemented lenses that easily delaminate in the infrared spectrum and have low transmittance. At the same time, the all-glass design ensures stable performance and long service life in extreme scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of a vehicle-mounted lens according to an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the MTF of the vehicle-mounted lens at an object distance of 0.75m in an embodiment of the present invention;

[0022] Figure 3 Schematic diagram of the MTF of the vehicle-mounted lens at an object distance of 1.5m in an embodiment of the present invention;

[0023] Figure 4 Schematic diagram of the MTF of the vehicle-mounted lens at infinite object distance in an embodiment of the present invention;

[0024] Figure 5 Schematic diagram of the relative illumination curve of the vehicle-mounted lens in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is described in detail below with reference to the embodiments and drawings.

[0026] like Figure 1 The figure shows an embodiment of a large-aperture, large-depth-of-field, short-wave infrared vehicle-mounted lens disclosed in the present invention. The lens comprises a negative-power convex-concave lens L1, a negative-power convex-concave lens L2, a positive-power convex-convex lens L3, a negative-power convex-concave lens L4, a positive-power convex-convex lens L5, a positive-power convex-convex lens L6, and a positive-power convex-convex lens L7, arranged sequentially along the optical axis from the object side to the image side. An aperture stop (STOP) is provided between lens L3 and lens L4, and a filter (Fliter) is provided between lens L7 and the image plane.

[0027] The refractive index Nd and Abbe number Vd of lenses L1-L7 respectively satisfy the following conditions: lens L1, 1.78≤Nd1≤1.84, 42≤Vd1≤50; lens L2, 1.57≤Nd2≤1.63, 55≤Vd2≤65; lens L3, 1.80≤Nd3≤1.92, 35≤Vd3≤42; lens L4, 1.90≤Nd4≤1.95, 15≤Vd4≤23; lens L5, 1.80≤Nd5≤1.92, 35≤Vd5≤42; lens L6, 1.80≤Nd6≤1.85, 38≤Vd6≤48; lens L7, 1.48≤Nd7≤1.63, 61≤Vd7≤72.

[0028] The focal lengths of lenses L1-L7 respectively satisfy the following conditions: lens L1, -12≤f1≤-2; lens L2, -50≤f2≤-35; lens L3, 13≤f3≤19; lens L4, -45≤f4≤-32; lens L5, 15≤f5≤25; lens L6, 12≤f6≤23; lens L7, 30≤f7≤47.

[0029] The basic parameters of the above-mentioned vehicle-mounted lens are shown in Table 1 below:

[0030] Table 1: Basic parameters of the optical system

[0031]

[0032] like Figure 1 As shown, in this embodiment, the onboard lens has an aperture number (FNO) of 1.6, a focal length (f) of 5.4mm, a total optical length (TTL) of 35mm, and a field of view (FOV) of 108°. In this embodiment, the onboard lens, while operating within a short-focus configuration with a large field of view, balances performance differences across different object distances by utilizing different lens powers. This allows the lens to achieve an excellent depth of field, enabling clear imaging at object distances from 0.75m to infinity.

[0033] In use, the lens L1 with negative focal length collects light emitted by an object, and the convex surface thereof facing the object side helps the light at a large angle to smoothly enter the system, the meniscus lens L2 with negative focal length is used for preliminary correction of spherical aberration and shortening of focal length, the lens L3 with positive focal length further converges the light to reduce the aperture, while reducing the incidence angle of the light into the subsequent system and preliminarily correcting aberration, the diaphragm is placed after the lens L3 to control the aperture of the entire optical system of the vehicle-mounted lens, while being conducive to the reduction of the overall size, the lens L4 with negative focal length and the lens L5 with positive focal length cooperate to eliminate the astigmatism and field curvature of the system, and the lens L6 and the lens L7 cooperate to converge the light at each field of view to the corresponding image point, while reducing the CRA of the light entering the image plane, so as to achieve the purpose of uniform illumination on the image plane.

[0034] The optical systems described above are all spherical mirrors and adopt a full-glass design, avoiding the temperature drift problem of a plastic lens system; the full single lens design avoids the problem that a cemented component is prone to opening in the infrared spectrum and has low transmittance; meanwhile, the large aperture is conducive to ensuring the brightness of imaging in a dim environment, the large depth of field is conducive to providing clear and accurate details and depth information, and the short total length is conducive to the integration of the lens into a target system; the overall structure is simple and regular in shape, and can adapt to the low-cost requirements of mass production.

[0035] The embodiment adopts a sampling frequency of 50 lp / mm, and the MTF curve diagram at 0.75 m to infinity object distance is shown in FIG. 3. Figures 2 to 4 As can be seen from the three graphs, the system field of view angle reaches ±54°, the best focal plane is at an object distance of 1.5 m, the MTF value is greater than 0.5, and the MTF at 0.75 m and infinity object distance is greater than 0.3, indicating that the lens has excellent depth of field and can provide good depth information for the vehicle. Meanwhile Figure 5 The relative illumination curve of the embodiment is shown, the abscissa represents different field angles, and the ordinate represents relative illumination. Figure 5 As can be seen from FIG. 4, the relative illumination of the system from the center to the edge is very uniform, avoiding the dark corner problem commonly seen in large field of view lenses.

[0036] The vehicle-mounted lens of the present application is applied in the short-wave infrared spectrum, and has the advantages of large aperture and large depth of field; compared with the visible light band or the near-infrared light band, it has good penetration and can penetrate fog, dust, smoke, etc., and can realize detection and imaging in special weather with low visibility.

Claims

1. A large-aperture, large-depth-of-field short-wave infrared vehicle-mounted lens, used in the short-wave infrared spectrum, characterized by: The vehicle-mounted lens is composed of a negative optical power lens L1, a negative optical power lens L2, a positive optical power lens L3, an aperture STOP, a negative optical power lens L4, a positive optical power lens L5, a positive optical power lens L6, and a positive optical power lens L7, which are distributed in sequence from the object plane to the image plane. The total optical length TTL, the effective aperture D, and the total focal length f of the vehicle-mounted lens satisfy 1.4≤f / D≤1.8 and 0.1≤f / TTL≤0.2; The object side surface of lens L1 is convex, and the image side surface is concave; the object side surface of lens L2 is convex, and the image side surface is concave; the object side surface of lens L3 is convex, and the image side surface is convex; the object side surface of lens L4 is convex, and the image side surface is concave; the object side surface of lens L5 is concave, and the image side surface is convex; the object side surface of lens L6 is convex, and the image side surface is convex; the object side surface of lens L7 is convex, and the image side surface is convex.

2. The large-aperture, large-depth-of-field short-wave infrared vehicle-mounted lens according to claim 1, characterized in that: The refractive index of the lens L1 is 1.78≤Nd1≤1.84, and the Abbe number is 42≤Vd1≤50; the refractive index of the lens L2 is 1.57≤Nd2≤1.63, and the Abbe number is 55≤Vd2≤65; the refractive index of the lens L3 is 1.80≤Nd3≤1.92, and the Abbe number is 35≤Vd3≤42; the refractive index of the lens L4 is 1.90≤Nd4≤1.95, and the Abbe number is 15≤Vd4≤23; the refractive index of the lens L5 is 1.80≤Nd5≤1.92, and the Abbe number is 35≤Vd5≤42; the refractive index of the lens L6 is 1.80≤Nd6≤1.85, and the Abbe number is 38≤Vd6≤48; the refractive index of the lens L7 is 1.48≤Nd7≤1.63, and the Abbe number is 61≤Vd7≤72.

3. The large-aperture, large-depth-of-field short-wave infrared vehicle-mounted lens according to claim 1, characterized in that: The focal length of the lens L1 is -12≤f1≤-2mm; the focal length of the lens L2 is -50≤f2≤-35mm; the focal length of the lens L3 is 13≤f3≤19mm; the focal length of the lens L4 is -45≤f4≤-32mm; the focal length of the lens L5 is 15≤f5≤25mm; the focal length of the lens L6 is 12≤f6≤23mm; and the focal length of the lens L7 is 30≤f7≤47mm.

4. The large-aperture, large-depth-of-field short-wave infrared vehicle-mounted lens according to claim 1, characterized in that: The total optical length TTL of the vehicle-mounted lens and the distance BFL from the center of the image side surface of the seventh lens to the image plane satisfy: TTL / BFL≤5.

5. The large-aperture, large-depth-of-field short-wave infrared vehicle-mounted lens according to claim 1, characterized in that: The total focal length f of the vehicle-mounted lens and the distance BFL from the center of the image side surface of the seventh lens to the image plane satisfy the following conditions: 0.5≤f / BFL≤1.

6. The large-aperture, large-depth-of-field short-wave infrared vehicle-mounted lens according to claim 1, characterized in that: The field of view angle of the vehicle-mounted lens is FOV=0°~108°.

7. The large-aperture, large-depth-of-field short-wave infrared vehicle-mounted lens according to claim 1, characterized in that: The effective imaging object distance of the vehicle-mounted lens is 0.75m to infinity without refocusing.

8. The large-aperture, large-depth-of-field short-wave infrared vehicle-mounted lens according to claim 1, characterized in that: The lenses L1 to L7 are all glass spherical single lenses.

9. The large-aperture, large-depth-of-field short-wave infrared vehicle-mounted lens according to claim 1, characterized in that: A filter is also provided between the lens L7 and the image plane.

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