Receiving lens and camera device applied to laser radar

Abstract

The utility model relates to a receiving lens applied to a laser radar and a camera device, the receiving lens applied to the laser radar comprises a first lens, a second lens, a diaphragm, a third lens and a fourth lens which are sequentially arranged from an object side to an image side, and the first lens and the third lens respectively have negative diopters. The second lens and the fourth lens respectively have positive diopter; the first lens and the second lens are respectively configured to be spherical lenses, and the third lens and the fourth lens are respectively configured to be aspheric lenses. According to the receiving lens applied to the laser radar, the focal length is 14.7 mm, the maximum target surface size can reach 6.8 mm, the maximum chief ray angle is smaller than 1 degree, the absolute value of optical distortion is smaller than 2%, and the relative distortion error with a transmitting lens is smaller than 0.3%.

Description

Technical Field

[0001] The present application relates to the technical field of optical imaging equipment, and in particular to a receiving lens and a camera device used in laser radar. Background Art

[0002] Lidar is a radar system that emits laser beams to detect the position, speed and other characteristic quantities of a target. Its working principle is to emit a detection signal (laser beam) to the target, and then compare the received signal reflected from the target (target echo) with the transmitted signal. After appropriate processing, relevant information about the target can be obtained, such as target distance, direction, altitude, speed, attitude, and even shape parameters, so as to detect, track and identify targets such as aircraft and missiles.

[0003] The detection accuracy of the laser radar equipment depends largely on the receiving accuracy of the receiving lens, so there are high requirements for the imaging resolution of the receiving lens. At the same time, most of the receiving lenses do not receive concentrated light beams, receive low energy, and are easily affected by interference signals. In addition, the detection distance of most receiving lenses on the market is short, so when detecting distant objects, the received energy is low, and the detection accuracy will decrease. In terms of distortion performance, in order to reduce system distortion, the distortion of the receiving lens should not be too large, and the relative distortion error with the transmitting lens should be as small as possible. Therefore, the field of view and effective focal length of the receiving lens have stricter tolerance requirements. When applied to the automotive field, the lens needs to have strong anti-interference ability, so the reliability of the lens is required to be high, and the system needs to meet normal use within a certain temperature range (-40℃-+85℃).

[0004] For example, there is a related technology that discloses a large-aperture single-photon laser radar lens, including a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged in sequence along the optical path, wherein the first lens is a plano-convex spherical lens with positive focal power, and the plane end is arranged close to the second lens, the second lens is a biconvex spherical lens with positive focal power, and the convex surface is arranged close to the first lens, the third lens is a concave-convex spherical lens with negative focal power, the fourth lens is a biconcave spherical lens with positive focal power, and the fifth lens and the sixth lens are both biconvex spherical lenses with positive focal power. This technology is committed to solving the technical problems of large lens volume, large distortion, small relative aperture, low spot uniformity, low energy utilization, and large noise interference. On the one hand, this technology still needs to be further improved in the system's maximum principal ray angle, relative illumination, detection distance and other performances, and on the other hand, it does not involve the improvement of the relative distortion error performance with the transmitting lens and the improvement of the technical problems of high and low temperature environment tolerance. Utility Model Content

[0005] In order to solve at least one of the above problems, the present application provides a receiving lens applied to a laser radar; and based on the receiving lens applied to the laser radar, a camera device is provided.

[0006] In the first aspect, the present application provides a receiving lens for laser radar, which adopts the following technical solution:

[0007] A receiving lens applied to a laser radar comprises a first lens, a second lens, an aperture, a third lens and a fourth lens arranged in sequence from an object side to an image side, wherein the first lens and the third lens respectively have negative refractive powers, and the second lens and the fourth lens respectively have positive refractive powers; the first lens and the second lens are respectively configured as spherical lenses, and the third lens and the fourth lens are respectively configured as aspherical lenses.

[0008] By adopting the above technical scheme, a first lens, a second lens, an aperture, a third lens and a fourth lens are designed. The aperture is located between the second lens and the third lens. The first lens to the second lens are the front group of the lens, and the third lens to the fourth lens are the rear group of the lens. The first lens and the third lens have negative refractive powers respectively, and the second lens and the fourth lens have positive refractive powers respectively. The first lens and the second lens are respectively configured as spherical lenses, and the third lens and the fourth lens are respectively configured as aspherical lenses. Based on the above structural design, a combination of two spherical lenses and two aspherical lenses is adopted to reasonably distribute the optical focal length of each lens, so as to realize a laser radar receiving lens with a focal length of 14.7 mm, a maximum target surface size of up to 6.8 mm, and a relatively uniform overall image quality; the third lens placed after the aperture adopts an aspherical lens, which can effectively correct spherical aberration and improve the resolution of the central field of view.

[0009] Preferably, the above-mentioned receiving lens applied to the laser radar satisfies the following condition: f1<0; wherein f1 is the focal length value of the first lens.

[0010] By adopting the above technical solution, as a specific structural example, the focal length of the first lens is designed to be less than zero, which is conducive to reducing the front diameter of the lens.

[0011] Preferably, the receiving lens used in the laser radar satisfies the following conditions: 1.8<n4<1.9, 39<V d4 <41; where n4 is the refractive index of the fourth lens, V d4 is the Abbe coefficient of the fourth lens.

[0012] By adopting the above technical solution, as a specific structural example, through the design of the refractive index and Abbe coefficient of the above-mentioned fourth lens, the fourth lens is placed in front of the image plane and is an aspherical lens, which can effectively correct off-axis aberrations, thereby improving the image quality of the off-axis field of view.

[0013] Preferably, the receiving lens used in the laser radar satisfies the following conditions:

[0014] 0.45<BFL / f<0.49; wherein f is the overall focal length of the lens, and BFL is the distance from the fourth lens element of the lens to the imaging plane on the optical axis.

[0015] By adopting the above technical solution, as a structural example, through the optimization design of the above BFL / f ratio, the total optical length of the lens can be effectively controlled, space can be reserved for the installation and focusing of optical components, interference between components can be avoided, and miniaturization can be facilitated.

[0016] Preferably, the above-mentioned receiving lens applied to the laser radar satisfies the following condition: y / f>0.45; wherein y is the diameter of the imaging surface of the lens, and f is the total focal length of the lens.

[0017] By adopting the above technical solution, as a structural example, through the optimization design of the above y / f ratio, the distortion can be effectively corrected, so that the absolute value of the distortion of the receiving lens is less than 2%, and the relative distortion error with the transmitting lens is less than 0.3%; the optimization design of the y / f ratio is also conducive to reducing the focal length and ensuring sufficient light receiving area to meet the illumination and miniaturization of the lens. The external dimensions of the receiving lens of this application are φ23.3mm*31mm, the aperture size is 1.2, and the relative illumination is greater than 98%.

[0018] Preferably, the above-mentioned receiving lens applied to the laser radar satisfies the following condition: BFL / TTL≥0.2; wherein, BFL is the distance from the fourth lens to the imaging plane on the optical axis, and TTL is the distance from the first lens to the imaging plane along the optical axis.

[0019] By adopting the above technical solution, as a structural example, by reasonably controlling the ratio of the optical back focus of the lens to the total optical length, it is beneficial to the assembly of the lens module and can improve the imaging quality.

[0020] Preferably, the first lens, the second lens, the third lens and the fourth lens are glass lenses respectively.

[0021] By adopting the above technical solution, as a structural example, the first lens, the second lens, the third lens and the fourth lens are all glass lenses.

[0022] Preferably, the first lens, the second lens and the fourth lens each have a convex object-side surface and a concave image-side surface, and the third lens has a concave object-side surface and a convex image-side surface.

[0023] By adopting the above technical solution, as a structural example, the first lens, the second lens, the third lens and the fourth lens adopt the above-mentioned object side surface and image side surface design. Through the combination of specific surface shapes and reasonable optical focal length distribution, the imaging quality of the lens can be effectively improved, the structure can be miniaturized, and good system performance can be maintained.

[0024] Preferably, the above-mentioned receiving lens applied to the laser radar consists of a first lens, a second lens, an aperture, a third lens and a fourth lens arranged in sequence from the object side to the image side.

[0025] By adopting the above technical solution, as a structural example, the receiving lens is only composed of a first lens, a second lens, an aperture, a third lens and a fourth lens, which can effectively control the number of lenses and reduce costs.

[0026] In a second aspect, the present application provides a camera device, which adopts the following technical solution:

[0027] A camera device includes the above-mentioned receiving lens applied to laser radar.

[0028] By adopting the above technical solution, the imaging function of the above-mentioned receiving lens applied to the laser radar can be further added to equipment such as vehicle-mounted cameras.

[0029] In summary, this application has the following beneficial effects:

[0030] 1. The receiving lens used for laser radar in the present application adopts two spherical lenses and two aspherical lenses. By reasonably allocating the optical focal length of each lens, a laser radar receiving lens with a focal length of 14.7 mm is realized, the maximum target surface size can reach 6.8 mm, and the overall image quality is relatively uniform;

[0031] 2. The receiving lens of the laser radar used in the present application has an optimal working object distance of 100m, and the energy of the central field of view within the enclosing radius of 3um is greater than 80%;

[0032] 3. The receiving lens used for laser radar in this application has an outer dimension of φ23.3mm*31mm, an aperture size of 1.2, and a relative illumination greater than 98%;

[0033] 4. The receiving lens used for laser radar in this application has a maximum defocus of less than 10um at -40°C to +85°C, and an angle change of less than 0.02°, which meets the use requirements of high and low temperature environments;

[0034] 5. The receiving lens of the laser radar used in the present application has a maximum principal ray angle of less than 1°, an absolute value of optical distortion of less than 2%, and a relative distortion error with the transmitting lens of less than 0.3%. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a light path diagram of a receiving lens applied to a laser radar in Example 1 of the present application;

[0036] Figure 2 is a point diagram of a receiving lens applied to a laser radar in Example 1 of the present application;

[0037] Figure 3 is a Diffraction Encircled Energy diagram of a receiving lens applied to a laser radar in Example 1 of the present application;

[0038] Figure 4 is a CRA diagram of a receiving lens applied to a laser radar in Example 1 of the present application;

[0039] Figure 5 is a light path diagram of a receiving lens applied to a laser radar in Example 2 of the present application;

[0040] Figure 6 is a spot diagram of a receiving lens applied to a laser radar in Example 2 of the present application;

[0041] Figure 7 is a Diffraction Encircled Energy diagram of a receiving lens applied to a laser radar in Example 2 of the present application;

[0042] Figure 8 is a CRA diagram of a receiving lens applied to a laser radar in Example 2 of the present application;

[0043] Fig. 9 is a light path diagram of a receiving lens applied to a laser radar in Example 3 of the present application;

[0044] Fig.10 is a spot diagram of a receiving lens applied to a laser radar in Example 3 of the present application;

[0045] Fig.11 is a Diffraction Encircled Energy diagram of a receiving lens applied to a laser radar in Example 3 of the present application;

[0046] Fig.12 This is a CRA diagram of the receiving lens applied to the laser radar in Example 3 of the present application.

[0047] Description of labels:

[0048] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Filter; 6. Protective sheet; 7. Imaging surface; 8. Aperture. DETAILED DESCRIPTION

[0049] The present application is further described in detail below with reference to the accompanying drawings and embodiments.

[0050] Example

[0051] See attached Figure 1-3 , wherein throughout all of these views, the same reference numerals denote corresponding components, and a receiving lens for a laser radar constructed according to an implementation shown in this embodiment can be seen in Figure 1 .

[0052] like Figure 1 , 5 As shown in Figures 1 and 9, the receiving lens used for laser radar in this embodiment includes: a first lens 1, a second lens 2, an aperture 8, a third lens 3, a fourth lens 4, a filter 5 and a protective sheet 6 arranged in sequence from the object side to the image side. The protective sheet has an imaging surface 7 near the image side. The first lens 1 and the third lens 3 have negative refractive powers, respectively, and the second lens 2 and the fourth lens 4 have positive refractive powers, respectively; the first lens 1 and the second lens 2 are configured as spherical glass lenses, respectively, and the third lens 3 and the fourth lens 4 are configured as aspherical glass lenses, respectively. The first lens 1, the second lens 2 and the fourth lens 4 each have a convex object side surface and a concave image side surface, respectively, and the third lens 3 has a concave object side surface and a convex image side surface.

[0053] Example 1

[0054] Example 1 corresponds to Figure 1 The receiving lens used for laser radar in the embodiment shown in the figure has corresponding experimental data graphs. Figure 2-4 .

[0055] Please refer to Table 1 for detailed optical data of this example.

[0056] Table 1

[0057]

[0058]

[0059] The focal length values ​​of the first lens 1 , the second lens 2 , the third lens 3 , the fourth lens 4 , the filter 5 and the protective film 6 of this embodiment are shown in Table 2.

[0060] Table 2

[0061] LENS focal length (1-2)P1 -50.6 (3-4)P2 17.1 (6-7)P3 -34.8 (8-9)P4 13.6 (10-11)P5 Infinity (12-13)P6 Infinity

[0062] In this embodiment, the aspheric parameters of the third lens 3 and the fourth lens 4 are shown in Table 3.

[0063] Table 3

[0064]

[0065] In the receiving lens of this embodiment: f=14.72, BFL=6.8, BFL / f=0.46, y=6.8, y / f=0.46, TTL=33, BFL / TTL=0.21. At the same time, on the basis of feasible processing, the tolerance of each component is strictly controlled so that the tolerance range of the field of view angle is not greater than 0.4 degrees.

[0066] In this embodiment, Figure 2 is the spot diagram of the receiving lens, Figure 3 Diffraction Encircled Energy diagram for the receiving lens, Figure 4 is the CRA diagram of the receiving lens; Figure 2-4 It can be seen that the maximum RMS radius of the entire field of view is no more than 6um, the energy of the central field of view with a radius of 3um is greater than 86%, and the maximum chief ray angle is less than 1 degree. It can be seen that the receiving lens of this embodiment can achieve good imaging quality.

[0067] Example 2

[0068] Example 2 corresponds to Figure 5 The receiving lens used for laser radar in the embodiment shown in the figure has corresponding experimental data graphs. Figure 6-8 .

[0069] Please refer to Table 4 for detailed optical data of this example.

[0070] Table 4

[0071] Surface number surface Radius of curvature Thickness interval Material Refractive Index Abbe number 1 First lens 39.4 1.2 Glass 1.5 64 2 10.4 3.2 3 Second lens 12.1 5.2 Glass 1.83 43 4 -164.7 0.1 5 Aperture endless 7.5 6 The third lens -4.9 3 Glass 1.5 64 7 -10.2 2.9 8 The fourth lens 6.8 4.2 Glass 1.8 41 9 17 2.5 10 Optical Filters endless 0.5 Glass 1.5 64 11 endless 3.3 12 Protective sheet endless 0.4 Glass 1.5 64 13 endless 0.47 14 Image plane endless

[0072] The focal length values ​​of the first lens 1 , the second lens 2 , the third lens 3 , the fourth lens 4 , the filter 5 and the protective film 6 of this embodiment are shown in Table 5.

[0073] Table 5

[0074] LENS focal length (1-2)P1 -28.2 (3-4)P2 14 (6-7)P3 -22.9 (8-9)P4 12.2 (10-11)P5 Infinity (12-13)P6 Infinity

[0075] In this embodiment, the aspheric parameters of the third lens 3 and the fourth lens 4 are shown in Table 6.

[0076] Table 6

[0077]

[0078]

[0079] In the receiving lens of this embodiment: f=14.8, BFL=7.17, BFL / f=0.48, y=6.8, y / f=0.46, TTL=34.5, BFL / TTL=0.21. At the same time, on the basis of feasible processing, the tolerance of each component is strictly controlled so that the tolerance range of the field of view angle is not greater than 0.4 degrees.

[0080] In this embodiment, Figure 6 is the spot diagram of the receiving lens, Figure 7 Diffraction Encircled Energy diagram for the receiving lens, Figure 8 is the CRA diagram of the receiving lens; Figure 6-8 It can be seen that the maximum RMS radius of the entire field of view is no more than 7um, the energy of the central field of view with a radius of 3um is greater than 85%, and the maximum chief ray angle is less than 1 degree. It can be seen that the receiving lens of this embodiment can achieve good imaging quality.

[0081] Example 3

[0082] Example 3 corresponds to Fig. 9 The receiving lens used for laser radar in the embodiment shown in the figure has corresponding experimental data graphs. Figure 10-12 .

[0083] Please refer to Table 7 for detailed optical data of this example.

[0084] Table 7

[0085]

[0086]

[0087] The focal length values ​​of the first lens 1 , the second lens 2 , the third lens 3 , the fourth lens 4 , the filter 5 and the protective film 6 of this embodiment are shown in Table 8.

[0088] Table 8

[0089] LENS focal length (1-2)P1 -24.3 (3-4)P2 13.9 (6-7)P3 -27.5 (8-9)P4 12.1 (10-11)P5 Infinity (12-13)P6 Infinity

[0090] In this embodiment, the aspheric parameters of the third lens 3 and the fourth lens 4 are shown in Table 9.

[0091] Table 9

[0092]

[0093] In the receiving lens of this embodiment: f=14.68, BFL=6.62, BFL / f=0.45, y=6.8, y / f=0.46, TTL=33.1, BFL / TTL=0.2. At the same time, on the basis of feasible processing, the tolerance of each component is strictly controlled so that the tolerance range of the field of view angle is not greater than 0.4 degrees.

[0094] In this embodiment, Fig.10 is the spot diagram of the receiving lens, Fig.11 DiffractionEncircledEncircledEnergy diagram of the receiving lens, Fig.12 is the CRA diagram of the receiving lens; Figure 10-12 It can be seen that the maximum RMS radius of the entire field of view is no more than 7um, the energy of the central field of view with a radius of 3um is greater than 82%, and the maximum chief ray angle is less than 1 degree. It can be seen that the receiving lens of this embodiment can achieve good imaging quality.

[0095] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed. However, as long as it is within the scope of the claims of the present application, it shall be protected by the patent law.

Claims

1. A receiving lens used in laser radar, characterized in that: The invention comprises a first lens, a second lens, an aperture, a third lens and a fourth lens which are arranged in sequence from the object side to the image side, wherein the first lens and the third lens respectively have negative refractive power, and the second lens and the fourth lens respectively have positive refractive power; the first lens and the second lens are respectively configured as spherical lenses, and the third lens and the fourth lens are respectively configured as aspherical lenses.

2. The receiving lens for laser radar according to claim 1, characterized in that: The following condition is satisfied: f1<0; wherein f1 is the focal length of the first lens.

3. The receiving lens for laser radar according to claim 1, characterized in that: Meet the following conditions: 1.8<n4<1.9, 39<V d4 <41; where n4 is the refractive index of the fourth lens, V d4 is the Abbe coefficient of the fourth lens.

4. The receiving lens for laser radar according to claim 1, characterized in that: The following conditions are met: 0.45<BFL / f<0.49; wherein f is the overall focal length of the lens, and BFL is the distance from the fourth lens element of the lens to the imaging plane on the optical axis.

5. The receiving lens for laser radar according to claim 1, characterized in that: The following condition is satisfied: y / f>0.45; wherein y is the diameter of the imaging surface of the lens, and f is the total focal length of the lens.

6. The receiving lens for laser radar according to claim 1, characterized in that: The following condition is satisfied: BFL / TTL≥0.2; wherein, BFL is the distance from the fourth lens to the imaging plane on the optical axis, and TTL is the distance from the first lens to the imaging plane along the optical axis.

7. The receiving lens for laser radar according to claim 1, characterized in that: The first lens, the second lens, the third lens and the fourth lens are glass lenses respectively.

8. The receiving lens for laser radar according to any one of claims 1 to 7, characterized in that: The first lens, the second lens and the fourth lens each have a convex object-side surface and a concave image-side surface, respectively, and the third lens has a concave object-side surface and a convex image-side surface.

9. The receiving lens for laser radar according to any one of claims 1 to 7, characterized in that: It consists of a first lens, a second lens, an aperture, a third lens and a fourth lens arranged in sequence from the object side to the image side.

10. A camera device, characterized in that: A receiving lens for laser radar comprising the receiving lens as described in any one of claims 1 to 9.

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