CN115268097A

CN115268097A - Optical system and laser radar with same

Info

Publication number: CN115268097A
Application number: CN202210850183.0A
Authority: CN
Inventors: 姜波
Original assignee: Ruichi Zhiguang Suzhou Technology Co ltd
Current assignee: Ruichi Zhiguang Suzhou Technology Co ltd
Priority date: 2022-07-20
Filing date: 2022-07-20
Publication date: 2022-11-01

Abstract

The invention discloses an optical system and a laser radar with the same. Wherein the first lens has positive refractive power; the second lens has positive refractive power; the third lens has positive refractive power; the fourth lens has negative refractive power; the fifth lens has positive refractive power; the sixth lens has positive refractive power; the seventh lens has a negative refractive power. The optical system can collimate the divergent laser light incident from the first side and then emit the collimated laser light from the second side. The laser radar comprises a lens mounting frame and a module mounting frame which are fixedly connected in an aligning mode. And the transmitting lens cone and the receiving lens cone are arranged in the lens mounting frame, and the optical systems are arranged in the transmitting lens cone and the receiving lens cone. And a laser emitting module and a laser receiving module are arranged in the module mounting frame. The laser emission module is aligned with the emission lens cone and is provided with a laser emitting laser; the laser receiving module is aligned with the receiving lens barrel and is provided with a sensor for sensing laser.

Description

Optical system and laser radar with same

Technical Field

The invention relates to the field of optics, in particular to an optical system and a laser radar with the same.

Background

Lidar is a radar system that emits a laser beam to detect the position, velocity, etc. of a target. The lidar may emit a probe signal (laser beam) towards the target and then compare the received echo signal reflected from the target with the probe signal. After proper processing, the information such as distance, direction, speed and the like of the target can be obtained, so that the target can be detected, tracked and identified. The laser radar generally comprises a transmitting module, a receiving module, a scanning module, an optical system, a processor and the like, wherein the transmitting module converts electric pulses into optical pulses to be transmitted out, and the receiving module restores the optical pulses reflected from a target into the electric pulses to be transmitted to the processor.

The optical system is an important component of the lidar, and as described above, the optical system is required to collimate the beam in the transmitting portion of the lidar and to receive the beam energy in the receiving portion.

Unlike an ordinary lens, the optical system of the receiving section of the laser radar does not require imaging, but light pulses from different positions need to be made incident on different positions of the receiving module. Also, it is necessary to collimate the laser light emitted from different positions at the emitting portion.

Disclosure of Invention

The invention provides an optical system capable of collimating laser light at a transmitting part and a receiving part and a laser radar having the same.

The technical scheme adopted by the invention is as follows: an optical system according to an embodiment of the present invention includes a lens group composed of seven lenses having refractive power, and a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens are arranged in this order from a first side to a second side. The first lens has positive refractive power, the first side surface of the first lens is a concave surface, and the second side surface of the first lens is a convex surface; the second lens has positive refractive power, and the first side surface of the second lens is a convex surface; the third lens has positive refractive power, and the first side surface of the third lens is a convex surface and the second side surface of the third lens is a concave surface; the fourth lens has negative refractive power, and the first side surface of the fourth lens is a concave surface; the fifth lens has positive refractive power, the first side surface of the fifth lens is a plane, and the second side surface of the fifth lens is a convex surface; the sixth lens has positive refractive power, and the first side surface of the sixth lens is a convex surface; the seventh lens has negative refractive power, and the first side surface of the seventh lens is a concave surface and the second side surface of the seventh lens is a concave surface. The optical system can collimate the divergent laser light incident from the first side and then emit the collimated laser light from the second side.

As an alternative of the technical solution of the present invention, the focal length of the lens group is 14.3mm.

As an alternative of the technical solution of the present invention, the first lens to the seventh lens are all made of H-ZK3 glass.

As an alternative of the technical solution of the present invention, the field of view of the optical system is not less than ± 15 °.

As an alternative of the technical solution of the present invention, a diaphragm is disposed between the fourth lens and the fifth lens.

As an alternative of the technical solution of the present invention, a laser radar according to another embodiment of the present invention includes a lens mounting bracket, a module mounting bracket, a laser emitting module, and a laser receiving module. The lens mounting rack is internally provided with a transmitting lens barrel and a receiving lens barrel, and the optical system is arranged in the transmitting lens barrel and the receiving lens barrel; the module mounting frame is fixedly connected with the lens mounting frame in an aligned manner and is arranged on the first side of the optical system, and a laser emitting module and a laser receiving module are arranged in the module mounting frame; the laser emission module is aligned with the emission lens cone and is provided with a laser for emitting laser; the laser receiving module is aligned with the receiving lens barrel and is provided with a sensor for sensing laser.

As an alternative of the technical scheme of the invention, the number of the lasers can be one or more.

As an alternative of the technical solution of the present invention, the transmitting lens barrel and the receiving lens barrel are arranged in parallel, the first lens to the seventh lens are arranged in the same direction, and the first lens is close to the laser transmitting module and the laser receiving module.

As an alternative of the technical solution of the present invention, the laser emitting module and the laser receiving module are disposed on the optical focal plane of the optical system.

The beneficial effects obtained by the invention are as follows: the optical system can collimate laser light rays diverging from one point of the focal plane to emit substantially parallel light, or can focus parallel light of the object plane to one point of the focal plane.

The effects of the present invention are not limited to the above-described effects, and those skilled in the art can derive the effects not described above from the following description.

Drawings

Fig. 1 is a perspective view showing an optical system lens group according to a first embodiment of the present invention.

Fig. 2 is a diagram showing an optical system configuration according to a first embodiment of the present invention.

Fig. 3 is an optical path diagram showing an optical system according to a first embodiment of the present invention.

Fig. 4 is a perspective view showing a laser radar according to a second embodiment of the present invention.

Fig. 5 is a sectional view showing a laser radar according to a second embodiment of the present invention.

Fig. 6 is a schematic view showing a laser emission module according to a third embodiment of the present invention.

Wherein, 100-optical focal plane; 110-a first lens; 120-a second lens; 130-a third lens; 140-a fourth lens; 150-diaphragm; 160-a fifth lens; 170-sixth lens; 180-seventh lens; 190-object plane; 200-a lens mount; 210-a module mount; 220-a transmission lens barrel; 230-a receiving barrel; 240-laser emission module; 241-laser; 250-laser receiving module.

Detailed Description

In order to make the technical problems, technical solutions and advantages solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the following specific examples are illustrative only and are not intended to limit the invention. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the following examples, belong to the scope of protection of the present invention.

It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "front", "rear", and the like indicate orientations or positional relationships based on drawings, and are merely intended to simplify the description of the present invention, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and operate, and thus should not be construed as limiting the present invention. In the description of the embodiments, the terms "disposed," "connected," and the like are to be construed broadly unless otherwise explicitly specified or limited. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

It is noted that the values given below for the various embodiments of the optical system are given by way of example and are not intended to be limiting. For example, one or more parameters of one or more surfaces of one or more lens elements in exemplary embodiments, as well as parameters of the materials comprising these elements, may be assigned different values while still providing similar performance to the optical system. It is noted that some of the values in the table may be scaled up or down to facilitate larger or smaller implementations of the optical systems of the present application.

The optical system of the present invention can be used for both the transmitting part and the receiving part of a lidar. For the optical system as shown in fig. 1 to 3, a transmitting module or a receiving module of the lidar may be arranged on the left side of the optical system, and the right side of the optical system may be the outer direction that the lidar needs to detect. Hereinafter, the left side of the optical system shown in fig. 1 to 3 is referred to as a first side, and the right side of the optical system shown in fig. 1 to 3 is referred to as a second side. The above definitions are provided to better illustrate the invention and do not limit the scope of the invention in a limiting manner.

[ first embodiment ].

As shown in fig. 1, the optical system lens group perspective view is composed of seven lenses having refractive power, and a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 160, a sixth lens 170, and a seventh lens 180 are sequentially disposed from a first side to a second side.

As shown in the configuration diagram of the optical system shown in fig. 2, in the present embodiment, the first lens 110 is a meniscus lens with positive refractive power, and both surfaces of the first lens 110 are spherical surfaces, and the first side surface thereof is a concave surface close to a plane, and the second side surface thereof is a convex surface.

The second lens element 120 is a biconvex lens element with positive refractive power, and both surfaces of the second lens element 120 are spherical surfaces, a first side surface of the second lens element is a convex surface close to a plane, and a second side surface of the second lens element is a convex surface.

The third lens 130 is a meniscus lens with positive refractive power, and both surfaces of the third lens 130 are spherical surfaces, a first side of which is a convex surface, and a second side of which is a concave surface close to a plane.

The fourth lens 140 is a biconcave lens having a negative refractive power, and both surfaces of the fourth lens 140 are spherical surfaces, and the first side surface and the second side surface thereof are concave surfaces.

The fifth lens 160 is a plano-convex lens having a positive refractive power, and the first side surface of the fifth lens 160 is a flat surface and the second side surface is a spherical convex surface.

The sixth lens 170 is a biconvex lens with positive refractive power, and both surfaces of the sixth lens 170 are spherical surfaces, a first side surface of which is a convex surface and a second side surface of which is a convex surface close to a plane.

The seventh lens 180 is a biconcave lens with negative refractive power, and both surfaces of the seventh lens 180 are spherical surfaces, a first side surface of which is a concave surface, and a second side surface of which is a concave surface close to a plane.

Preferably, in the optical system, a diaphragm 150 may be further included, and the diaphragm 150 may be an aperture diaphragm 150 to facilitate realization of a small FNO. Also, more reflected light can be received by the diaphragm 150. Preferably, the aperture 150 is located between the fourth lens 140 and the fifth lens 160, so as to facilitate effective collection of light and reduce the aperture of the lens of the optical system. Of course, the diaphragm 150 may be positioned between any other lenses as will be appreciated by those skilled in the art.

Next, with reference to fig. 2 and table 1, a specific embodiment of the optical system of the present invention will be described.

As shown in fig. 2 and table 1, the optical system according to the present embodiment sequentially includes, from the first side to the second side: assume a focal plane 100 having a surface S1; a meniscus-shaped first lens 110 having a positive refractive power, having a first surface S2 concave to a first side and a second surface S3 convex to a second side; a biconvex second lens 120 having a positive refractive power, having a first surface S4 convex to a first side and a second surface S5 convex to a second side; a meniscus-shaped third lens 130 having a positive refractive power, having a first surface S6 convex to the first side and a second surface S7 concave to the second side; a double concave fourth lens 140 having a negative refractive power, having a first surface S8 concave to a first side and a second surface S9 concave to a second side; the diaphragm 150 is assumed to have a surface S10; a plano-convex fifth lens 160 having a positive refractive power, having a flat first surface S11 and a convex second surface S12 to the second side; a biconvex sixth lens 170 having a positive refractive power, having a first surface S13 convex to the first side and a second surface S14 convex to the second side; a double concave seventh lens 180 having a negative refractive power, having a first surface S15 concave to a first side and a second surface S16 concave to a second side; assume an object plane 190 with a surface S17.

For the above-described optical system for the laser radar transmitting portion, the focal plane 100 may correspond to the installation position of the laser transmitting module 240; for the above-described optical system for the laser radar receiving part, the focal plane 100 may correspond to a mounting position of the laser receiving module 250.

Lens data of the above optical system are shown in table 1 below.

[ TABLE 1 ]

In the above table, a positive radius of curvature indicates that the center of curvature is on the right side (second side) of the surface, and a negative radius of curvature indicates that the center of curvature is on the left side (first side) of the surface. Thickness or pitch refers to the axial distance from the current surface to the next surface. Wherein the focal length of the whole lens group is 14.3mm, the Numerical Aperture (NA) is 2, and the material is H-ZK3 type glass.

As shown in the optical path diagram of the optical system of this embodiment in fig. 3, the laser light (for a wavelength of 905 ± 20 nm) emitted from any point on the optical focal plane 100 by the laser emission module 240 is collimated by the lens group and then emitted from the second side as substantially parallel light to reach the object plane 190. The laser light emitted from different positions on the focal plane 100 corresponds to different emitting positions and angles. Similarly, the parallel light reflected from the object plane 190 enters the lens group from the second side and is finally focused to a point on the focal plane 100. The reflected light rays at different positions and angles are focused at different points on the focal plane 100.

The characteristics and advantages of the optical system according to the present embodiment may include, but are not limited to, one or more of the following.

1) The optical system has seven lenses. In some embodiments, all lens elements have spherical surfaces, which can reduce cost.

2) The optical system comprises an (aperture) stop 150, for example located between the fourth lens 140 and the fifth lens 160.

3) In some embodiments, the optical system may be integrated with a scanning mirror system (e.g., a MEMS mirror or a rotating mirror) to collect laser radiation from a remote object and receive signals with sufficient accuracy at a receiving module located at the focal plane 100.

4) The optical system can be optimized for compact transmit/receive modules, scaled up or down.

5) Light rays diverging from any one point on the first side focal plane 100 can be collimated to be emitted as substantially parallel light on the second side, or parallel light incident on the second side can be focused to one point on the focal plane 100. For example, by emitting laser light in a substantially parallel manner, a long-distance (several hundred meters) object can be detected.

6) The laser light emitted from different positions of the focal plane 100 is emitted in different orientations at the second side of the optical system, so that the effective line count of the lidar can be increased.

7) The optical system may provide a field of view of no less than ± 15 ° (30 ° in sum).

[ second embodiment ].

The structure and performance of the optical system of the first embodiment are explained above with reference to fig. 1 to 3, and next, the lidar having the above optical system is further explained with reference to fig. 4 and 5.

The perspective view of the lidar shown in fig. 4 includes a lens mounting bracket 200 and a module mounting bracket 210, and the lens mounting bracket 200 and the module mounting bracket 210 are fixedly connected end to end in an aligned manner. The lens mount 200 is provided therein with a transmitting lens barrel 220 and a receiving lens barrel 230, and the transmitting lens barrel 220 and the receiving lens barrel 230 have through holes therein adapted to insert an optical system. A laser light emitting module 240 is disposed in the module mount 210 at a position aligned with the emission lens barrel 220, and a laser light receiving module 250 is disposed in the module mount 210 at a position aligned with the reception lens barrel 230.

As shown in the cross-sectional view of the lidar shown in fig. 5, a transmitting barrel 220 is used to insert the optical system of the transmitting portion and a receiving barrel 230 is used to insert the optical system of the receiving portion. For example, the optical system of the emitting portion may be inserted into the upper through hole, and the optical system of the receiving portion may be inserted into the lower through hole. Here, the optical system of the emitting portion and the optical system of the receiving portion are both the optical systems described in the first embodiment.

The laser emitting module 240 and the laser receiving module 250 of the lidar are located at the rear side of the lens barrel, and the first side of the optical system described in the first embodiment is the side close to the module mounting bracket 210. The emission divergence point of the laser emission module 240 is located on the focal plane 100 of the optical system, and the photosensitive surface of the laser receiving module 250 is located on the focal plane 100 of the optical system.

In addition, in order to prevent the emitted laser from affecting the laser receiving module 250 in the module mounting bracket 210, the module mounting bracket 210 is provided with an interlayer between the laser emitting module 240 and the laser receiving module 250, and the laser emitting module 240 and the laser receiving module 250 are installed in a staggered manner.

[ third embodiment ].

Hereinabove, the laser radar having the optical system described in the first embodiment is explained with reference to fig. 4 and 5. Next, a laser light emitting module 240 and a laser light receiving module 250 located on the first side of the optical system in the second embodiment will be explained with reference to fig. 6.

The laser emitting module 240 of the lidar may be a single laser 241, or may include a plurality of lasers 241, and the lasers 241 may be Edge Emitting Lasers (EELs) or Vertical Cavity Surface Emitting Lasers (VCSELs). The plurality of lasers 241 may be arranged along a line passing through an optical axis of the optical system in the vicinity of the optical focal plane 100 of the optical system. Further, the plurality of lasers 241 are arranged in a vertical direction. A plurality of lasers 241 may also be integrated to form a line laser, and at this time, a portion of the line laser emitting a laser beam may be regarded as one laser 241.

The emission divergence point of each laser 241 is located at the focal plane 100 shown in fig. 3, so that the divergent laser light emitted from the plurality of lasers 241 becomes a plurality of collimated light rays after passing through the optical system. Although fig. 6 illustrates a case where 16 lasers 241 are included, the present invention is not limited thereto, and the number of lasers 241 may be increased or decreased as needed.

As shown in fig. 6, the plurality of lasers 241 are arranged in a line pattern along a vertical direction, but the present invention is not limited thereto, and the plurality of lasers 241 may be arranged in two lines perpendicular to an optical axis direction. Alternatively, the plurality of lasers 241 may be arranged dispersedly, and the optical system may collimate the laser light emitted from the plurality of lasers 241, respectively, even if the lasers 241 are not arranged in a straight line.

In the present embodiment, the sensor of the laser receiving module 250 may also adopt an arrangement similar to the laser 241 shown in fig. 6. The number of sensors is less than or equal to the number of lasers 241.

The above-described embodiments of the optical system and the lidar having the same are merely exemplary and preferred embodiments, and are not intended to limit the present invention, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of the present invention. In addition, the technical solutions between the various embodiments may be combined with each other, but must be based on the realization of those skilled in the art; where combinations of features are mutually inconsistent or impractical, such combinations should not be considered as being absent and not within the scope of the claimed invention.

Claims

1. An optical system comprising a lens group composed of seven lenses having refractive power, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens being arranged in this order from a first side to a second side;

the first lens has positive refractive power, and the first side surface of the first lens is a concave surface and the second side surface of the first lens is a convex surface;

the second lens has positive refractive power, and the first side surface of the second lens is a convex surface;

the third lens has positive refractive power, and the first side surface of the third lens is a convex surface and the second side surface of the third lens is a concave surface;

the fourth lens has negative refractive power, the first side surface of the fourth lens is a concave surface, and the second side surface of the fourth lens is a concave surface;

the fifth lens has positive refractive power, the first side surface of the fifth lens is a plane, and the second side surface of the fifth lens is a convex surface;

the sixth lens has positive refractive power, and the first side surface of the sixth lens is a convex surface;

the seventh lens has negative refractive power, and the first side surface of the seventh lens is a concave surface;

wherein the optical system is capable of collimating the divergent laser light incident from the first side and emitting the collimated laser light from the second side.

2. The optical system of claim 1 wherein said lens group focal length is 14.3mm.

3. The optical system of claim 1, wherein the first through seventh lenses are all made of H-ZK3 glass.

4. The optical system of claim 1 wherein the field of view of the optical system is not less than ± 15 °.

5. The optical system of claim 1, wherein a stop is disposed between the fourth lens and the fifth lens.

6. A lidar, comprising:

the optical system of any one of claims 1 to 5;

the optical system comprises a lens mounting frame, a transmitting lens barrel and a receiving lens barrel are arranged in the lens mounting frame, and the optical system is arranged in the transmitting lens barrel and the receiving lens barrel;

the module mounting frame is fixedly connected with the lens mounting frame in an aligned mode and arranged on the first side of the optical system, and a laser emitting module and a laser receiving module are arranged in the module mounting frame;

a laser emission module aligned with the emission lens barrel and having a laser emitting laser;

and the laser receiving module is aligned with the receiving lens cone and is provided with a sensor for sensing laser.

7. Lidar of claim 6, wherein said laser may be one or more.

8. The lidar of claim 6, wherein the transmitting cylinder and the receiving cylinder are disposed parallel to each other, the first through seventh lenses are arranged in the same direction, and the first lens is adjacent to the laser transmitting module and the laser receiving module.

9. The lidar of claim 7, wherein the laser transmit module and the laser receive module are disposed on the optical system focal plane.