A lidar lens and lidar

Abstract

This utility model discloses a lidar lens and a lidar, the lidar lens comprising a first lens, a second lens, and a third lens arranged sequentially along the optical axis from the object side to the image side; the first lens has positive optical power, the second lens has negative optical power, and the third lens has positive optical power; the first, second, and third lenses are all glass spherical lenses. This utility model, by employing a three-glass spherical lens structure with a positive-negative-positive optical power distribution, can achieve a target surface size of 9.6mm or larger in diameter, realizing clear imaging projection in the infrared band. Furthermore, the lens features low distortion, small size, and low cost, thus allowing it to be used with laser light sources and is compatible with laser light sources with a emission angle within 20°.

Description

Technical Field

[0001] This utility model relates to the field of optical lens technology, and in particular to a lidar lens and a lidar. Background Technology

[0002] With the rapid development of AI technology, intelligent robots are increasingly being used in various fields (such as warehousing, autonomous driving, and logistics). To adapt to more complex environments, robots need higher-precision environmental perception capabilities. Traditional environmental perception technologies (such as ultrasonic sensors, infrared sensors, or cameras) have limitations, including susceptibility to environmental noise, sensitivity to lighting conditions, and difficulty in generating real-time 3D environmental information. Therefore, LiDAR lenses, which offer advantages in high precision, strong anti-interference capabilities, and rapid modeling, are becoming increasingly important, meaning that the performance requirements for LiDAR lenses in the robotics field are growing daily.

[0003] However, current LiDAR lenses still require further breakthroughs in the following areas:

[0004] 1. In order to acquire information more accurately, the optical system needs to be equipped with a larger chip with higher resolution, so the requirements for the resolution capability of the lens itself are also getting higher and higher.

[0005] 2. As the number of sensors required by the robot increases, the available internal space becomes increasingly limited, and the size of the lens needs to be further reduced;

[0006] 3. As the requirements for recognition accuracy of equipment become increasingly stringent, this means that lenses need more elements to meet performance requirements, making the search for lower-cost solutions a trend. Utility Model Content

[0007] This invention provides a lidar lens and lidar, which achieve higher resolution capabilities while reducing size and cost, and can be matched with larger size and higher resolution chips.

[0008] In a first aspect, the present invention provides a lidar lens, comprising an aperture, a first lens, a second lens, and a third lens arranged sequentially along the optical axis from the object side to the image side;

[0009] The first lens has positive optical power, the second lens has negative optical power, and the third lens has positive optical power;

[0010] The first lens, the second lens, and the third lens are all glass spherical lenses.

[0011] Optionally, the object-side surface of the first lens is convex, and the image-side surface is either convex or planar;

[0012] The object-side surface of the second lens is concave, and the image-side surface is also concave.

[0013] The object-side surface of the third lens is convex, and the image-side surface is also convex.

[0014] Optionally, the lidar lens satisfies the following conditions:

[0015]

[0016] in, The optical focal length of the laser radar lens is [missing information]. The optical power of the first lens is... The optical power of the second lens is [value]. The optical power of the third lens is denoted as .

[0017] Optionally, the lidar lens satisfies the following conditions:

[0018] 1.80≤n1≤2.05;

[0019] 1.45≤n²≤1.76;

[0020] 1.80≤n1≤2.05;

[0021] Wherein, n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, and n3 is the refractive index of the third lens.

[0022] Optionally, the lidar lens satisfies the following condition: 0.35 <BFL / ImgH<0.45;

[0023] Wherein, BFL is the distance from the image side of the third lens to the imaging surface, and ImgH is the diagonal length of the effective pixel area on the imaging surface of the lidar lens.

[0024] Optionally, the lidar lens satisfies the following condition: 2.38 < ΦL3 / ΦL2 < 2.82;

[0025] Wherein, ΦL2 is the effective optical aperture of the second lens, and ΦL3 is the effective optical aperture of the third lens.

[0026] Optionally, the lidar lens satisfies the following condition: 1.75 <TTL / ImgH<2.15;

[0027] Wherein, TTL is the total optical length of the lidar lens, and ImgH is the diagonal length of the effective pixel area on the imaging surface of the lidar lens.

[0028] Optionally, it may also include an aperture stop located on the object side of the first lens or between the first lens and the second lens.

[0029] Secondly, this utility model embodiment also provides a lidar, including a transmitter and a receiver, wherein the transmitter includes a laser source and a lidar lens as described in any of the first aspects; the lidar lens is located on the light-emitting side of the laser source.

[0030] The technical method provided by this utility model adopts a three-glass spherical lens structure with positive and negative positive optical power distribution, which can achieve a target surface size of more than 9.6mm in diameter, realize clear imaging projection function in the infrared band, and the lens has the characteristics of low distortion, small size and low cost, so it can be used with laser light source and is compatible with laser light source with emission angle within 20°. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a lidar lens provided in Embodiment 1 of this utility model;

[0032] Figure 2 for Figure 1 The modulation transfer function curve of the radar laser lens is shown.

[0033] Figure 3 for Figure 1 The field curvature distortion curve of the radar laser lens is shown.

[0034] Figure 4 This is a schematic diagram of the structure of a lidar lens provided in Embodiment 2 of this utility model;

[0035] Figure 5 for Figure 4 The modulation transfer function curve of the radar laser lens is shown.

[0036] Figure 6 for Figure 4 The field curvature distortion curve of the radar laser lens is shown.

[0037] Figure 7 This is a schematic diagram of the structure of a lidar lens provided in Embodiment 3 of this utility model;

[0038] Figure 8 for Figure 7 The modulation transfer function curve of the radar laser lens is shown.

[0039] Figure 9 for Figure 7 The diagram shows the field curvature distortion curve of the radar laser lens. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0041] Figure 1 This is a schematic diagram of the structure of a lidar lens provided in Embodiment 1 of this utility model, for reference. Figure 1 The lidar lens includes an aperture STO, a first lens 1, a second lens 2, and a third lens 3 arranged sequentially along the optical axis from the object side to the image side; the first lens 1 has positive optical power, the second lens 2 has negative optical power, and the third lens 3 has positive optical power; the first lens 1, the second lens 2, and the third lens 3 are all glass spherical lenses.

[0042] First, for optical lenses, optical power equals the difference between the image-side beam convergence and the object-side beam convergence; it characterizes the optical system's ability to deflect light. The larger the absolute value of optical power, the stronger the bending ability of light; the smaller the absolute value, the weaker the bending ability. When optical power is positive, the refraction of light is converging; when optical power is negative, the refraction of light is diverging. Optical power can be used to characterize a single refractive surface of a lens (i.e., one surface of the lens), a single lens, or a system formed by multiple lenses (i.e., a lens group).

[0043] Secondly, the lidar lens provided in this embodiment is mainly used in conjunction with a laser light source to form the transmitter of a lidar system. This lidar lens can house all lenses within a single lens barrel. Figure 1 (not shown in the image) such as Figure 1 As shown in this embodiment, a fixed-focus lens is formed by setting three glass spherical lenses, and the optical power of these three lenses is coordinated to achieve a simple, miniaturized, and stable optical lens design. Specifically, the three glass spherical lenses are distributed with positive and negative positive optical power, which allows light to propagate smoothly without excessive refraction on any one surface, resulting in good image quality, reduced aberrations, lower sensitivity, and a compact structure, achieving a large field of view and miniaturization. Furthermore, this embodiment uses all three lenses as glass spherical lenses, i.e., an all-glass lens, which offers better thermal stability compared to a glass-plastic hybrid lens.

[0044] In one specific embodiment, optionally, the object-side surface of the first lens 1 is convex, and the image-side surface is convex or flat; the object-side surface of the second lens 2 is concave, and the image-side surface is concave; the object-side surface of the third lens 3 is convex, and the image-side surface is convex.

[0045] Wherein, the first lens 1 is substantially a meniscus positive lens or a plano-convex lens. The first lens 1 can converge the light passing therethrough, reduce the incident angle of light, improve relative illumination, and reduce lens sensitivity. The second lens 2 is substantially a biconcave lens, and the second lens 2 can diverge light and change the direction of light in different fields of view. The third lens 3 is substantially a biconvex glass spherical lens, and the third lens 3 facilitates light collection and improves the chief ray angle of the edge field of view.

[0046] In a specific embodiment, optionally, the lidar lens satisfies the following conditions: Wherein, is the optical power of the lidar lens, is the optical power of the first lens 1, is the optical power of the second lens 2, is the optical power of the third lens 3.

[0047] In a specific embodiment, optionally, the lidar lens satisfies the following conditions: 1.80≤n1≤2.05; 1.45≤n2≤1.76; 1.80≤n3≤2.05; wherein, n1 is the refractive index of the first lens 1, n2 is the refractive index of the second lens 2, and n3 is the refractive index of the third lens 3.

[0048] Under the above conditions, reasonable optical power distribution combined with appropriate refractive index and Abbe number can effectively correct system aberrations and improve the resolution capability of the lens.

[0049] In a specific embodiment, optionally, the lidar lens satisfies the following condition: 0.35<BFL / ImgH<0.45; wherein, BFL is the distance from the image side surface of the third lens 3 to the imaging plane, and ImgH is the diagonal length of the effective pixel area on the imaging plane of the lidar lens.

[0050] In a specific embodiment, optionally, the lidar lens satisfies the following condition: 1.75<TTL / ImgH<2.15; wherein, TTL is the total optical length of the lidar lens, and ImgH is the diagonal length of the effective pixel area on the imaging plane of the lidar lens.

[0051] In a specific embodiment, optionally, the lidar lens satisfies the following condition: 2.38<ΦL3 / ΦL2<2.82; wherein, ΦL2 is the optically effective aperture of the second lens 2, and ΦL3 is the optically effective aperture of the third lens 3.

[0052] In a specific embodiment, optionally, the lidar lens further comprises a stop STO, and the stop STO is located on the object side of the first lens 1 or between the first lens 1 and the second lens 2.

[0053] Meanwhile, setting an aperture stop STO on the object side of the first lens 1 or between the first lens 1 and the second lens 2 allows for precise control of the amount of light transmitted by limiting the specific position of the aperture stop STO in the entire optical system. This increases the height of the central principal ray at the position of the aperture stop STO, widens the aperture, and ensures the amount of light transmitted through the aperture stop STO, thus ensuring image brightness. In addition, the aperture stop STO can block off-axis light rays, effectively reducing off-axis aberrations and ensuring image sharpness.

[0054] Based on the same concept, this utility model provides three different specific embodiments, and their optical power relationship and related physical optical parameter design ranges are shown in Table 1:

[0055] Table 1 shows the relationship between the optical power of each lens and the design values ​​of related physical and optical parameters in the three embodiments.

[0056]

[0057] In Embodiment 1 of this utility model, reference is made to... Figure 1 Knowing the structure, shape, and location of each component in the system is crucial. In this embodiment, the image-side surface of the first lens 1 is convex, and the aperture stop STO is located on the object-side of the first lens 1. The optical performance parameters of this lidar lens are as follows: focal length: 11.67mm, aperture: F2.3, field of view: 46°, total optical length: 18.9mm, image size: like Figure 1 The parameter design values ​​of each lens in the lidar lens of Embodiment 1 are shown in Table 2:

[0058] Table 2 shows a design value for each lens in the lidar lens of Example 1.

[0059]

[0060]

[0061] The surface numbers in Table 2 are assigned according to the surface sequence of each lens. "STO" represents the aperture stop of the lens; "S7" represents the image plane of the lens; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. "Infinity" indicates that the surface is flat and the radius of curvature is infinite; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface, with a blank space indicating that the current position is air.

[0062] Figure 2 for Figure 1 The modulation transfer function (MJF) curve of the radar laser lens is shown, where the vertical axis represents the MJF value and the horizontal axis represents the frequency. The simulated wavelength range is 890 nm to 920 nm. Figure 2 It can be seen that the modulation transfer function values ​​of each frequency under different fields of view are all controlled within a reasonable range. The modulation transfer function values ​​in the entire field of view are all above 0.4 in the 17lp / mm band, indicating that the image of the lidar lens is uniform and meets the imaging requirements of the lidar transmitter.

[0063] Figure 3 for Figure 1 The diagram shows the field curvature distortion curve of the radar laser lens. In the coordinate system on the left side of the diagram, the horizontal axis represents the magnitude of the field curvature in mm; the vertical axis represents the normalized image height (unitless); where T represents the meridion and S represents the sagitta; from Figure 3 It can be seen that the radar laser lens provided in this embodiment effectively controls the field curvature, that is, during imaging, the difference in image quality between the center and the periphery is small; in the coordinate system on the right, the horizontal coordinate represents the magnitude of distortion, in percentage; the vertical coordinate represents the normalized image height, which has no unit; from Figure 3 As can be seen, the distortion of the lens provided in this embodiment has been well corrected, with F-theta distortion less than 0.7% and imaging distortion being relatively small.

[0064] Figure 4 This is a schematic diagram of the structure of a lidar lens provided in Embodiment 2 of this utility model, for reference. Figure 4 In Embodiment 2 of this utility model, the structural composition, shape, and position of each component of the system are crucial to the system. In the lidar lens of Embodiment 2, the aperture stop STO is set on the object-side surface of the first lens 1, and the image-side surface of the first lens 1 is flat. The optical performance parameters of this lidar lens are as follows: focal length: 11.83mm, aperture: F2.4, field of view: 46°, total optical length: 19.9mm, image size: like Figure 4 The parameter design values ​​of each lens in the lidar lens of Embodiment 2 are shown in Table 3:

[0065] Table 3 shows a design value for each lens in the lidar lens in Example 2.

[0066]

[0067]

[0068] The surface numbers in Table 3 are assigned according to the surface sequence of each lens. "STO" represents the aperture stop of the lens; "S7" represents the image plane of the lens; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. "Infinity" indicates that the surface is flat and the radius of curvature is infinite; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface, with a blank space indicating that the current position is air.

[0069] Figure 5 for Figure 4 The modulation transfer function (MJF) curve of the radar laser lens is shown, where the vertical axis represents the MJF value and the horizontal axis represents the frequency. The simulated wavelength range is 890 nm to 920 nm. Figure 5 It can be seen that the modulation transfer function values ​​of each frequency under different fields of view are all controlled within a reasonable range. The modulation transfer function values ​​in the entire field of view are all above 0.4 in the 17lp / mm band, indicating that the image of the lidar lens is uniform and meets the imaging requirements of the lidar transmitter.

[0070] Figure 6 for Figure 4 The diagram shows the field curvature distortion curve of the radar laser lens. In the coordinate system on the left side of the diagram, the horizontal axis represents the magnitude of the field curvature in mm; the vertical axis represents the normalized image height (unitless); where T represents the meridion and S represents the sagitta; from Figure 6 It can be seen that the radar laser lens provided in this embodiment effectively controls the field curvature, that is, during imaging, the difference in image quality between the center and the periphery is small; in the coordinate system on the right, the horizontal coordinate represents the magnitude of distortion, in percentage; the vertical coordinate represents the normalized image height, which has no unit; from Figure 6 As can be seen, the distortion of the lens provided in this embodiment has been well corrected, with F-theta distortion less than 1% and imaging distortion being relatively small.

[0071] Figure 7 This is a schematic diagram of the structure of a lidar lens provided in Embodiment 3 of this utility model, for reference. Figure 7 In Embodiment 3 of this utility model, the structural composition, shape, and position of each component of the system are crucial to the system. In the lidar lens of Embodiment 3, the aperture stop is positioned between the first lens 1 and the second lens 2. The optical performance parameters of this lidar lens are as follows: focal length: 12.14mm, aperture: F 2.27, field of view: 46°, total optical length: 17.9mm, image size: φ9.56mm. Figure 7The parameter design values ​​of each lens in the lidar lens of Embodiment 3 are shown in Table 4:

[0072] Table 4 shows a design value for each lens in the lidar lens in Example 3.

[0073]

[0074] The surface numbers in Table 4 are assigned according to the surface sequence of each lens. "STO" represents the aperture stop of the lens; "S7" represents the image plane of the lens; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. "Infinity" indicates that the surface is flat and the radius of curvature is infinite; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface, with a blank space indicating that the current position is air.

[0075] Figure 8 for Figure 7 The modulation transfer function (MJF) curve of the radar laser lens is shown, where the vertical axis represents the MJF value and the horizontal axis represents the frequency. The simulated wavelength range is 890 nm to 920 nm. Figure 8 It can be seen that the modulation transfer function values ​​of each frequency under different fields of view are all controlled within a reasonable range. The modulation transfer function values ​​in the entire field of view are all above 0.4 in the 17lp / mm band, indicating that the image of the lidar lens is uniform and meets the imaging requirements of the lidar transmitter.

[0076] Figure 9 for Figure 7 The diagram shows the field curvature distortion curve of the radar laser lens. In the coordinate system on the left side of the diagram, the horizontal axis represents the magnitude of the field curvature in mm; the vertical axis represents the normalized image height (unitless); where T represents the meridion and S represents the sagitta; from Figure 9 It can be seen that the radar laser lens provided in this embodiment effectively controls the field curvature, that is, during imaging, the difference in image quality between the center and the periphery is small; in the coordinate system on the right, the horizontal coordinate represents the magnitude of distortion, in percentage; the vertical coordinate represents the normalized image height, which has no unit; from Figure 9 As can be seen, the distortion of the lens provided in this embodiment has been well corrected, with F-theta distortion less than 1.25% and low imaging distortion.

[0077] Based on the same concept, this utility model also provides a lidar. The lidar in this utility model includes a transmitter and a receiver. The transmitter includes a laser source and a lidar lens as described in any embodiment of this utility model; the lidar lens is located on the light-emitting side of the laser source. It should be noted that in this embodiment, the laser source is specifically located on the image plane of the lidar lens on the image side. Furthermore, since this lidar uses the lidar lenses of the above embodiments, the lidar provided in this embodiment also has the same beneficial effects as the aforementioned lidar lenses.

[0078] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A lidar lens, characterized in that, It includes a first lens, a second lens, and a third lens arranged sequentially from the object side to the image side along the optical axis; The first lens has positive optical power, the second lens has negative optical power, and the third lens has positive optical power; The first lens, the second lens, and the third lens are all glass spherical lenses.

2. The lidar lens according to claim 1, characterized in that, The object-side surface of the first lens is convex, and the image-side surface is either convex or flat. The object-side surface of the second lens is concave, and the image-side surface is also concave. The object-side surface of the third lens is convex, and the image-side surface is also convex.

3. The lidar lens according to claim 1, characterized in that, The lidar lens meets the following conditions: 0.541 < φ1 / φ < 0.664; -0.643 < φ2 / φ < -0.475; 0.777 < φ3 / φ < 0.826; Wherein, φ is the optical power of the lidar lens, φ1 is the optical power of the first lens, φ2 is the optical power of the second lens, and φ3 is the optical power of the third lens.

4. The lidar lens according to claim 1, characterized in that, The lidar lens meets the following conditions: 1.80≤n1≤2.05； 1.45≤n2≤1.76； 1.80≤n1≤2.05； Wherein, n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, and n3 is the refractive index of the third lens.

5. The lidar lens according to claim 1, characterized in that, The lidar lens meets the following condition: 0.35 <BFL / ImgH<0.45; Wherein, BFL is the distance from the image side of the third lens to the imaging surface, and ImgH is the diagonal length of the effective pixel area on the imaging surface of the lidar lens.

6. The lidar lens according to claim 1, characterized in that, The lidar lens satisfies the following condition: 2.38 < ΦL3 / ΦL2 < 2.82; Wherein, ΦL2 is the effective optical aperture of the second lens, and ΦL3 is the effective optical aperture of the third lens.

7. The lidar lens according to claim 1, characterized in that, The lidar lens meets the following condition: 1.75 <TTL / ImgH<2.15; Wherein, TTL is the total optical length of the lidar lens, and ImgH is the diagonal length of the effective pixel area on the imaging surface of the lidar lens.

8. The lidar lens according to claim 1, characterized in that, It also includes an aperture stop, which is located on the object side of the first lens or between the first lens and the second lens.

9. A lidar, characterized in that, It includes a transmitter and a receiver, wherein the transmitter includes a laser light source and a lidar lens as described in any one of claims 1-8; the lidar lens is located on the light-emitting side of the laser light source.

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