Laser radar and transmitting lens and receiving lens used for laser radar

Abstract

The invention discloses a laser radar which comprises a transmitting lens and a receiving lens. The transmitting lens comprises a first lens, a second lens and a third lens which are sequentially arranged in the optical axis transmission direction, the first lens and the third lens are both meniscus positive lenses with the concave surfaces facing the laser side, and the second lens is a meniscus negative lens with the convex surface facing the laser side; the receiving lens comprises a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged in the optical axis transmission direction, the fourth lens is a meniscus positive lens with the convex surface facing the object side, the fifth lens is a biconcave lens, the sixth lens is a biconvex lens, and the seventh lens is a meniscus negative lens with the convex surface facing the object side. According to the laser radar, the number of lenses of the transmitting lens and the receiving lens is small, the structure is compact, and the space utilization rate in the laser radar can be improved.

Description

Technical Field

[0001] The present application belongs to the field of laser radar technology, and specifically relates to a laser radar and a transmitting lens and a receiving lens used for the laser radar. Background Art

[0002] With the continuous development of intelligent driving technology, cars are gradually transforming from traditional means of transportation to higher-level intelligent products. As the current mainstream automotive intelligent driving sensor, LiDAR has broad development prospects in the fields of civilian automobiles and industrial automation. LiDAR has the advantages of high precision, high resolution and long detection distance. Its working principle is to emit a laser of a specific wavelength to the detection area, and then compare the reflected laser with the outgoing laser to obtain the geometric information and motion information of the objects in the detection area. The existing LiDAR has a large number of lenses. Summary of the invention

[0003] The technical problem to be solved by the present application is that the existing laser radar has a large number of lenses. In order to solve this technical problem, a laser radar and a transmitting lens and a receiving lens for the laser radar are provided.

[0004] The technical solution proposed in this application is: A transmitting lens for a laser radar comprises a first lens, a second lens and a third lens which are arranged in sequence along the transmission direction of an optical axis, wherein the first lens and the third lens are both positive meniscus lenses with a concave surface facing a laser side, and the second lens is a negative meniscus lens with a convex surface facing the laser side.

[0005] Furthermore, the air interval between the laser and the first lens on the optical axis is 4.93 mm, the air interval between the first lens and the second lens on the optical axis is 4.13 mm, and the air interval between the second lens and the third lens on the optical axis is 12.96 mm.

[0006] Furthermore, the center thickness of the first lens is 2.7 mm, the radius of curvature of the side surface facing the laser is -33.88 mm, and the radius of curvature of the side surface facing away from the laser is -12.9 mm; the center thickness of the second lens is 4.13 mm, the radius of curvature of the side surface facing the laser is 15.56 mm, and the radius of curvature of the side surface facing away from the laser is 8 mm; the center thickness of the third lens is 3 mm, the radius of curvature of the side surface facing the laser is -36 mm, and the radius of curvature of the side surface facing away from the laser is -13.24 mm.

[0007] Furthermore, the total optical length TTL, effective focal length EFL, emission angle and maximum optical distortion Distmax of the transmitting lens meet the following conditions: 28mm<TTL<31mm, 25mm<EFL<29mm, the emission angle is -10.79°~10.79°, Distmax<1.8%.

[0008] A receiving lens for a laser radar is matched with the transmitting lens for the laser radar as described above, and the transmitting lens and the receiving lens are used for light with a main wavelength of 905nm.

[0009] Furthermore, the receiving lens includes a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence along the transmission direction of the optical axis, the fourth lens is a positive meniscus lens with the convex surface facing the object side, the fifth lens is a double concave lens, the sixth lens is a double convex lens, and the seventh lens is a negative meniscus lens with the convex surface facing the object side.

[0010] Furthermore, the air interval between the fourth lens and the fifth lens on the optical axis is 2.02 mm, the air interval between the fifth lens and the sixth lens on the optical axis is 3.06 mm, the air interval between the sixth lens and the seventh lens on the optical axis is 2.54 mm, and the air interval between the seventh lens and the image plane on the optical axis is 4.61 mm.

[0011] Furthermore, the center thickness of the fourth lens is 3.72 mm, the radius of curvature of the object side is 13.64 mm, and the radius of curvature of the image side is 79.49 mm; the center thickness of the fifth lens is 3 mm, the radius of curvature of the object side is -22.72 mm, and the radius of curvature of the image side is 20.59 mm; the center thickness of the sixth lens is 4 mm, the radius of curvature of the object side is 30.25 mm, and the radius of curvature of the image side is -14.63 mm; the center thickness of the seventh lens is 4 mm, the radius of curvature of the object side is 11.48 mm, and the radius of curvature of the image side is 7.66 mm.

[0012] Furthermore, the total optical length TTL, effective focal length EFL, field of view FOV and maximum optical distortion Distmax of the receiving lens meet the following conditions: TTL<31mm, 15mm<EFL<18mm, FOV is -10.5°~10.5°, Distmax<0.2%.

[0013] A laser radar comprises the transmitting lens for the laser radar as described above and the receiving lens for the laser radar as described above.

[0014] With the above-mentioned laser radar, the number of lenses of the transmitting lens and the receiving lens are both small, the structure is compact, and the space utilization inside the laser radar can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are used to provide further understanding of the present application and constitute a part of the specification. They are used to explain the present application together with the embodiments of the present application and do not constitute a limitation of the present application.

[0016] Figure 1 A schematic diagram of the structure of a transmitting lens for a laser radar provided in one embodiment of the present application; Figure 2 for Figure 1 The spot diagram of the transmitting lens corresponding to different fields of view in a 20°C environment is shown; Figure 3 for Figure 1 The spot diagram of the transmitting lens corresponding to different fields of view in a -40°C environment is shown; Figure 4 for Figure 1 The spot diagram of the transmitting lens corresponding to different fields of view in a 125°C environment is shown; Figure 5 for Figure 1 Schematic diagram of field curvature and distortion of the transmitting lens shown; Figure 6 A schematic diagram of the structure of a receiving lens for a laser radar provided in one embodiment of the present application; Figure 7 for Figure 6 The receiving lens shown in the figure corresponds to different fields of view in a 20°C environment; Figure 8 for Figure 6 The spot diagram of the receiving lens corresponding to different fields of view in a -40°C environment is shown; Fig. 9 for Figure 6 The receiving lens shown in the figure has a spot diagram corresponding to different fields of view in a 125°C environment; Fig.10 for Figure 6 Schematic diagram of field curvature and distortion of the receiving lens shown.

[0017] Description of labels: 11. First lens; 12. Second lens; 13. Third lens; 21. Fourth lens; 22. Fifth lens; 23. Sixth lens; 24. Seventh lens. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0019] The present application provides a laser radar, which includes a transmitting lens and a receiving lens, and the transmitting lens and the receiving lens match each other to detect geometric information and motion information of an object. Figure 1 and Figure 6 As shown, the transmitting lens includes a first lens, a second lens and a third lens sequentially arranged along the transmission direction of the optical axis, the first lens and the third lens are both positive meniscus lenses with the concave surface facing the laser side, and the second lens is a negative meniscus lens with the convex surface facing the laser side; the receiving lens includes a fourth lens, a fifth lens, a sixth lens and a seventh lens sequentially arranged along the transmission direction of the optical axis, the fourth lens is a positive meniscus lens with the convex surface facing the object side, the fifth lens is a double concave lens, the sixth lens is a double convex lens, and the seventh lens is a negative meniscus lens with the convex surface facing the object side.

[0020] In one embodiment, the total optical length TTL, effective focal length EFL, maximum optical distortion Distmax, and exit angle or field of view FOV of the transmitting lens and the receiving lens meet the following conditions: Transmitting lens: 28mm<TTL<31mm, 25mm<EFL<29mm, Distmax<1.8%, exit angle is -10.79°~10.79°; receiving lens: TTL<31mm, 15mm<EFL<18mm, FOV is -10.5°~10.5°, Distmax<0.2%.

[0021] In addition, the maximum field of view laser divergence angle θ of the transmitting lens is less than 1.53 mrad, and the root mean square radius RMS of the receiving lens is less than 4 mm. It can be seen that the laser can be collimated by the first lens, the second lens and the third lens, and the collimation is high; and the aberration correction of the receiving lens is good.

[0022] It should be noted that the above-mentioned transmitting lens and receiving lens are both used for light with a main wavelength of 905nm, and the exit pupil of the transmitting lens and the entrance pupil of the receiving lens match each other in position and size; at the same time, since the exit angle of the transmitting lens is slightly larger than the field of view angle of the receiving lens, the transmitting lens and the receiving lens match each other.

[0023] In one embodiment, in the transmitting lens, the first lens, the second lens and the third lens are all made of glass, and the Abbe number Vd of the glass is ≥23, so as to facilitate the athermal design at -40°C to 125°C. In the receiving lens, the fourth lens, the fifth lens and the seventh lens are all made of glass, and the sixth lens is made of molded glass, so as to facilitate the athermal design of the receiving lens at -40°C to 125°C. At the same time, the object side of the sixth lens is an aspherical surface, and the use of molded glass material can reduce the processing cost of the aspherical lens.

[0024] In order to facilitate understanding of the technical solution of the present application, a specific embodiment is provided here for illustration: Example 1 For the emitting lens: As shown in Table 1, the air spacing between the laser and the first lens on the optical axis is 4.93 mm, the air spacing between the first lens and the second lens on the optical axis is 4.13 mm, and the air spacing between the second lens and the third lens on the optical axis is 12.96 mm.

[0025] Furthermore, the center thickness of the first lens is 2.7 mm, the radius of curvature of the side surface facing the laser is -33.88 mm, and the radius of curvature of the side surface facing away from the laser is -12.9 mm; the center thickness of the second lens is 4.13 mm, the radius of curvature of the side surface facing the laser is 15.56 mm, and the radius of curvature of the side surface facing away from the laser is 8 mm; the center thickness of the third lens is 3 mm, the radius of curvature of the side surface facing the laser is -36 mm, and the radius of curvature of the side surface facing away from the laser is -13.24 mm.

[0026] In this embodiment, the total optical length TTL of the emitting lens is 30.72 mm, the effective focal length EFL is 27.88 mm, and the emission angle is -10.79° to 10.79°.

[0027] Table 1 Component parameters of the transmitting lens For the receiving lens: as shown in Table 2, the air interval between the fourth lens and the fifth lens on the optical axis is 2.02 mm, the air interval between the fifth lens and the sixth lens on the optical axis is 3.06 mm, the air interval between the sixth lens and the seventh lens on the optical axis is 2.54 mm, and the air interval between the seventh lens and the image plane on the optical axis is 4.61 mm.

[0028] Furthermore, the center thickness of the fourth lens is 3.72 mm, the radius of curvature of the object side is 13.64 mm, and the radius of curvature of the image side is 79.49 mm; the center thickness of the fifth lens is 3 mm, the radius of curvature of the object side is -22.72 mm, and the radius of curvature of the image side is 20.59 mm; the center thickness of the sixth lens is 4 mm, the radius of curvature of the object side is 30.25 mm, and the radius of curvature of the image side is -14.63 mm; the center thickness of the seventh lens is 4 mm, the radius of curvature of the object side is 11.48 mm, and the radius of curvature of the image side is 7.66 mm.

[0029] In this embodiment, the total optical length of the receiving lens is TTL=26.95 mm, the effective focal length is EFL=16.12 mm, the half field of view is HFOV=10.5°, and the GEO radius is less than 8.3 μm.

[0030] Table 2 Parameters of receiving lens components It should be noted that in Figure 1 and Figure 6 In the figure, light is transmitted from left to right, so along the transmission direction of the optical axis, the left side of the lens is the laser side or the object side, and the right side of the lens in the receiving lens is the image side. Combined with Table 1 and Table 2, taking the first lens and the fourth lens as examples, the left side of the first lens is the S1 surface and the right side is the S2 surface, the left side of the fourth lens is the S7 surface and the right side is the S8 surface, and the other lenses are the same, which will not be described here.

[0031] Figures 2 to 4 is a spot diagram of the transmitting lens in the above embodiment at 20°C, -40°C and 125°C respectively, Figure 5 Schematic diagram of field curvature and distortion of the transmitting lens in the above embodiment. Figures 7 to 9 is a spot diagram of the receiving lens in the above embodiment at 20°C, -40°C and 125°C respectively, Fig.10 Schematic diagram of field curvature and distortion of the receiving lens in the above embodiment. In combination with the above figures, it can be seen that the transmitting lens and the receiving lens in the above embodiment have at least the following advantages: 1. The emission lens has a good collimation effect on the light beam. For a VCSEL laser light source with a main wavelength of 905nm, the emission angle of the lens can reach -10°~10°; 2. The maximum GEO radius of the receiving lens does not exceed 8.3μm, so it is suitable for SPAD (Single-Photon Avalanche Diode) detectors with pixels larger than 8μm, and the field of view of the receiving lens is -10.5°~10.5°, which can meet the long-distance detection requirements of LiDAR; 3. The aperture of the transmitting lens and the receiving lens is small, and the number of lenses of both are small, the structure is compact, and the space utilization rate inside the lidar can be improved; 4. The lenses in the transmitting lens and the receiving lens are made of glass. The lenses with aspherical surfaces are also made of molded glass, which is low in cost, easy to process, and can work normally in an environment of -40℃~125℃.

[0032] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A transmitting lens for laser radar, characterized in that: It comprises a first lens, a second lens and a third lens which are arranged in sequence along the transmission direction of the optical axis. The first lens and the third lens are both positive meniscus lenses with the concave surface facing the laser side, and the second lens is a negative meniscus lens with the convex surface facing the laser side.

2. The transmitting lens for laser radar according to claim 1, characterized in that: The air interval between the laser and the first lens on the optical axis is 4.93 mm, the air interval between the first lens and the second lens on the optical axis is 4.13 mm, and the air interval between the second lens and the third lens on the optical axis is 12.96 mm.

3. The transmitting lens for laser radar according to claim 1, characterized in that: The center thickness of the first lens is 2.7mm, the radius of curvature of the side surface facing the laser is -33.88mm, and the radius of curvature of the side surface facing away from the laser is -12.9mm; the center thickness of the second lens is 4.13mm, the radius of curvature of the side surface facing the laser is 15.56mm, and the radius of curvature of the side surface facing away from the laser is 8mm; the center thickness of the third lens is 3mm, the radius of curvature of the side surface facing the laser is -36mm, and the radius of curvature of the side surface facing away from the laser is -13.24mm.

4. The transmitting lens for laser radar according to claim 1, characterized in that: The total optical length TTL, effective focal length EFL, emission angle and maximum optical distortion Distmax of the transmitting lens meet the following conditions: 28mm<TTL<31mm, 25mm<EFL<29mm, the emission angle is -10.79°~10.79°, Distmax<1.8%.

5. A receiving lens for laser radar, characterized in that: The transmitting lens for laser radar is matched with the transmitting lens for laser radar as described in any one of claims 1 to 4, and the transmitting lens and the receiving lens are used for light with a main wavelength of 905nm.

6. The receiving lens for laser radar according to claim 5, characterized in that: The receiving lens includes a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence along the transmission direction of the optical axis, the fourth lens is a positive meniscus lens with a convex surface facing the object side, the fifth lens is a double concave lens, the sixth lens is a double convex lens, and the seventh lens is a negative meniscus lens with a convex surface facing the object side.

7. The receiving lens for laser radar according to claim 6, characterized in that: The air interval between the fourth lens and the fifth lens on the optical axis is 2.02 mm, the air interval between the fifth lens and the sixth lens on the optical axis is 3.06 mm, the air interval between the sixth lens and the seventh lens on the optical axis is 2.54 mm, and the air interval between the seventh lens and the image plane on the optical axis is 4.61 mm.

8. The receiving lens for laser radar according to claim 6, characterized in that: The center thickness of the fourth lens is 3.72mm, the radius of curvature of the object side is 13.64mm, and the radius of curvature of the image side is 79.49mm; the center thickness of the fifth lens is 3mm, the radius of curvature of the object side is -22.72mm, and the radius of curvature of the image side is 20.59mm; the center thickness of the sixth lens is 4mm, the radius of curvature of the object side is 30.25mm, and the radius of curvature of the image side is -14.63mm; the center thickness of the seventh lens is 4mm, the radius of curvature of the object side is 11.48mm, and the radius of curvature of the image side is 7.66mm.

9. The receiving lens for laser radar according to claim 5, characterized in that: The total optical length TTL, effective focal length EFL, field of view FOV and maximum optical distortion Distmax of the receiving lens meet the following conditions: TTL<31mm, 15mm<EFL<18mm, FOV is -10.5°~10.5°, Distmax<0.2%.

10. A laser radar, characterized in that: It comprises the transmitting lens for laser radar as described in any one of claims 1-4 and the receiving lens for laser radar as described in any one of claims 5-9.

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