CN115267799A

CN115267799A - Light splitting device and laser radar

Info

Publication number: CN115267799A
Application number: CN202110483935.XA
Authority: CN
Inventors: 王吉; 叶文炜; 向少卿
Original assignee: Hesai Technology Co Ltd
Current assignee: Hesai Technology Co Ltd
Priority date: 2021-04-30
Filing date: 2021-04-30
Publication date: 2022-11-01

Abstract

A beam splitter and a lidar, the beam splitter being adapted for use in a lidar for coaxial transceiving, comprising: the transmitting light of the laser radar forms echo light after being reflected by a target object; the light splitting device includes: a first region corresponding to a position of a light emitted from the lidar, the first region being for eliminating a blind area of the lidar; a second region surrounding the first region; when the first area reflects the emitted light to the target object, the transmissivity of the second area is not equal to that of the first area; or when the first area transmits the emitted light to the target object, the reflectivity of the second area is not equal to that of the first area. The light splitting device is arranged in the first area, echo light shielded by the light splitting device can be effectively reduced, the strength of collected echo signals is improved, the near field detection capability of the laser radar is improved, and a near field blind area is reduced.

Description

Light splitting device and laser radar

Technical Field

The invention relates to the field of laser detection, in particular to a light splitting device and a laser radar.

Background

Laser radar is a range finding sensor commonly used, has characteristics such as detection range is far away, resolution ratio is high, receive environmental disturbance little, and the wide application is in fields such as intelligent robot, unmanned aerial vehicle, unmanned driving. In recent years, the automatic driving technology has been rapidly developed, and the laser radar has become indispensable as a core sensor for distance sensing.

According to different layout modes of a transmitting light path and a receiving light path, the laser radar can be divided into non-coaxial transmitting and receiving and coaxial transmitting and receiving, the transmitting light path and the receiving light path of the non-coaxial transmitting and receiving are independent of each other and are generally realized by adopting different lens groups to respectively bear the transmitting and receiving functions of laser, the transmitting light path and the receiving light path of the coaxial transmitting and receiving share a common optical axis and often share a transmitting and receiving lens group, and the separation and the combination of the transmitting light beam and the receiving light beam are realized through light splitting elements (such as a spectroscope, a small-hole reflector and the like).

The non-coaxial receiving and transmitting needs to be provided with independent transmitting and receiving modules, so that the laser radar is large in size and not compact in structure; in addition, the non-coaxial transceiving has the problems of complex assembly and adjustment and higher cost.

However, the existing laser radar adopting coaxial transceiving is often weak in near-field detection capability and has a large near-field blind area.

Disclosure of Invention

The invention provides a light splitting device and a laser radar to improve the short-distance target detection capability.

In order to solve the above problems, the present invention provides a spectroscopic apparatus, which is suitable for a laser radar that receives and transmits coaxially, comprising:

the emitting light of the laser radar forms echo light after being reflected by a target object; the light splitting device includes: a first region corresponding to a position of emitted light of the lidar, the first region for eliminating a blind zone of the lidar; a second region surrounding the first region; when the first area reflects the emitted light to the target object, the transmissivity of the second area is not equal to that of the first area; or when the first area transmits the emitted light to the target object, the reflectivity of the second area is not equal to the reflectivity of the first area.

Optionally, when the first region reflects the emitted light to the target object, the first region transmits a part of the echo light, and the second region transmits the echo light.

Optionally, the transmittance of the second region is greater than the transmittance of the first region.

Optionally, the transmittance of the first region is in the range of 2% to 10%.

Optionally, when the first region transmits the emission light to the target object, the first region partially reflects the echo light, and the second region reflects the echo light.

Optionally, the reflectivity of the second region is greater than the reflectivity of the first region.

Optionally, the reflectivity of the first region is in the range of 2% to 10%.

Optionally, the shape of the first region in the plane of the beam incident surface of the light splitting device is the same as the spot shape of the emitted light on the surface of the light splitting device.

Optionally, the laser radar includes a VCSEL laser, and the shape of the first region is an ellipse in the plane of the beam incident surface of the beam splitting device; or the laser radar includes an EEL laser, and the shape of the first area is circular in the plane of the beam incident surface of the beam splitting device.

Optionally, when the first region reflects the emitted light to the target object, the light splitting device includes an incident surface, a back surface and a plurality of connection surfaces, the incident surface and the back surface are opposite to each other, the connection surfaces are located between the incident surface and the back surface, and the emitted light is projected to the incident surface; and the connecting surface facing the transmitting module of the laser radar faces back to the receiving device of the laser radar.

Optionally, an included angle between a normal direction of the connection surface facing the emission module and the direction vector of the echo light is greater than or equal to 90 °.

Optionally, an optical axis of a part of the emitted light is orthogonal to an optical axis of a part of the echo light, and the emitted light is incident on the incident surface at an angle θ; and the included angle between the connecting surface facing the transmitting module and the normal negative direction of the incident surface is greater than or equal to theta.

Optionally, when the first region reflects the emitted light to the target object, the light splitting device includes an incident surface, a back surface and a plurality of connection surfaces, the incident surface and the back surface are opposite to each other, the connection surfaces are located between the incident surface and the back surface, and the emitted light is projected to the incident surface; the connecting surface back to the emitting module is parallel to the echo light.

Optionally, when the first region reflects the emitting light to the target object, the lidar further includes: a light-shielding sheet on a path of the emitted light transmitting the first region.

Optionally, one end of the light shielding sheet is fixedly connected with the light splitting device, and the other end of the light shielding sheet extends in a direction parallel to the echo light.

Optionally, the receiving device of the laser radar includes a receiving lens, and the other end of the light shielding plate extends to the receiving lens and contacts with a surface of the receiving lens.

Optionally, a shape of a side surface of the light shielding sheet facing a receiving module side of the laser radar is adapted to a surface shape of the receiving lens.

Optionally, in a height direction, a size of the light shielding sheet is equal to a size of the receiving lens, and the height direction is orthogonal to both the emitted light and the echo light.

Correspondingly, the invention also provides a laser radar, comprising:

an emitting device adapted to generate the emitted light; a receiving device adapted to receive the echo light; the light splitting device is the light splitting device provided by the invention.

Optionally, the emitted light acted by the light splitting device is coaxial with the echo light.

Optionally, the method further includes: the transmitted light acted by the light splitting device is reflected by the rotating mirror and then is emitted to a three-dimensional space; after the reflection of the rotating mirror, the echo light is received by the receiving device after the action of the light splitting device.

Compared with the prior art, the technical scheme of the invention has the following advantages:

in the technical scheme of the invention, the first area and the second area have different effects on the light beam: when the first area reflects the emitted light to the target object, the transmissivity of the second area is not equal to that of the first area; or when the first area transmits the emitted light to the target object, the reflectivity of the second area is not equal to that of the first area, and the first area corresponding to the position of the laser radar emitted light is used for eliminating the blind area of the laser radar. Therefore, the light splitting device is provided with the first area, echo light shielded by the light splitting device can be effectively reduced, the intensity of collected echo signals is improved, and the purposes of improving the near field detection capability and reducing the near field blind area are achieved.

In an alternative aspect of the present invention, when the first region reflects the emitted light, the transmittance of the first region is in a range of 2% to 10%; the first region has a reflectance in a range of 2% to 10% when the first region transmits the emitted light. The transmissivity or reflectivity of the first area is set within a reasonable range, so that the intensity of an echo signal of a near-distance target can be improved while the intensity of emitted light is not influenced as much as possible.

In an alternative aspect of the present invention, when the first region reflects the emitted light to the target, the light splitting device includes an incident surface, a back surface, and a plurality of connection surfaces, the incident surface and the back surface are opposite to each other, the connection surfaces are located between the incident surface and the back surface, and the emitted light is projected to the incident surface; and the connecting surface close to the transmitting module of the laser radar faces back to the receiving device of the laser radar. Because the connecting surface close to the transmitting module of the laser radar faces back to the receiving device of the laser radar, the light beams reflected by the connecting surface towards the receiving module of the laser radar are effectively reduced, and the aims of suppressing stray light and reducing interference to echo light can be achieved.

In an alternative aspect of the present invention, when the first region reflects the emitted light to the target, the light splitting device includes an incident surface, a back surface, and a plurality of connection surfaces, the incident surface and the back surface are opposite to each other, the connection surfaces are located between the incident surface and the back surface, and the emitted light is projected to the incident surface; the connecting surface back to the emitting module is parallel to the echo light so as to reduce the influence of the light splitting device on the echo light as much as possible.

In an alternative aspect of the present invention, when the first region reflects the emitted light to the target object, the lidar further includes: a light-shielding sheet located on an optical path of the emitted light that transmits the first region. The light shielding sheet can absorb stray light, so that interference on echo signals is reduced.

In an alternative scheme of the invention, one end of the light shielding sheet is fixedly connected with the light splitting device, and the other end of the light shielding sheet extends along a direction parallel to the echo light. The direction of messenger along parallel echo light extends, can minimize the influence of anti-dazzling screen setting to echo light to guarantee echo signal intensity, guarantee detectability.

In an alternative scheme of the invention, one end of the light shielding sheet is fixedly connected with the light splitting device, and the other end of the light shielding sheet extends along a direction parallel to the echo light; and the receiving module of the laser radar comprises a receiving lens, and the other end of the shading sheet extends to the receiving lens and is in contact with the surface of the receiving lens. The other end of the light shielding sheet is in contact with the surface of the receiving lens, so that the light shielding sheet can provide additional mechanical support, the stability of the light shielding sheet is guaranteed, the interference of mechanical vibration is reduced, especially in a vehicle-mounted laser radar, the influence of the vibration interference on a light path can be reduced, and the stability of the detection capability of the laser radar is improved.

Drawings

FIG. 1 is a schematic diagram of an optical path structure of a laser radar;

FIG. 2 is a schematic diagram of the optical paths of the lidar shown in FIG. 1 for detecting near and far targets;

FIG. 3 is a schematic diagram showing the spot shape of the echo light in coaxial transceiving on the receiving device side of the laser radar shown in FIG. 1;

FIG. 4 is a comparison of the range of a light spot formed on one side of the receiving device by coaxial transceiving and the range of a light beam collected by the receiving device;

FIG. 5 is a schematic diagram of an optical path structure of another laser radar;

FIG. 6 is a schematic structural diagram of an embodiment of the light splitting device of the present invention;

FIG. 7 is a schematic front view of the beam-incident surface of the embodiment of the light-splitting device shown in FIG. 6;

FIG. 8 is a graph of the spot shape in the cross section of the emitted light and the spot shape of the emitted light projected onto the light-splitting device in the embodiment of the light-splitting device shown in FIG. 6;

FIG. 9 is a schematic cross-sectional view of the embodiment of the light-splitting device shown in FIG. 6;

FIG. 10 is a schematic view of another embodiment of the light-splitting device of the present invention;

FIG. 11 is a schematic structural diagram of a light splitting device according to yet another embodiment of the present invention;

FIG. 12 is a schematic diagram of the structure of the light-shielding plate and the receiving lens in the light-splitting device of FIG. 11;

fig. 13 is a schematic structural diagram of a light splitting device according to another embodiment of the present invention.

Detailed Description

As known from the background art, the lidar employing coaxial transceiving in the prior art often has a problem of weak near-field detection capability. The reason that the detection capability is weak is analyzed by combining the light path structure of a laser radar:

referring to fig. 1, a schematic diagram of the optical path structure of a lidar is shown.

The laser radar is a laser radar adopting coaxial receiving and transmitting. The coaxial transmission and reception used in the laser radar includes a center reflection beam splitting method, and the center reflection beam splitting method is illustrated as an example in fig. 1.

As shown in fig. 1, a light beam 11a generated by the emitting module 11 is reflected by the light splitting device 12 to form an emitting light 12a emitted toward the three-dimensional space, and the emitting light 12a is reflected by the target 10 to form an echo light 12b projected to the receiving module 13.

The coaxial transmitting and receiving scheme of central reflection has the problem of weak near-distance echo signals. The main reason for this is the problem of blocking the echo light of a near-distance target.

Referring to fig. 2, a schematic diagram of the optical paths of the lidar shown in fig. 1 for detecting a short-distance target and a long-distance target is shown.

For laser radar, especially for vehicle laser radar, long distance measurement is a very important index. Therefore, the optical path of the laser radar optical system (mainly composed of optical components such as lenses or lens groups) is mainly designed for the long-distance target 21, and the focal length of the optical system is also set for the long-distance target 21; when the short-distance target 22 is detected, the optical system of the laser radar is usually in a defocusing state, and the ratio of the echo light to be shielded is larger the closer the target distance is; the weaker the intensity of the echo light, the lower the target detection probability.

As shown in fig. 2, in the coaxial transceiving using the central reflection mode in fig. 1, the emitted light in the area 24 (i.e., the area of the oval dashed line in fig. 2) is reflected; the near target 22 reflects the emitted light to form a spot 23 of echo light; only the region outside the region 24 of the echo light can be picked up by the receiving device. Specifically, as shown in fig. 3, in the coaxial transmission and reception at the receiving device side, the spots of the echo light are concentric circles, and the blank area at the center thereof corresponds to the position where the emitted light is reflected (the position indicated by the area 31 in fig. 3).

Reference is also made to fig. 4, wherein fig. 4 is a comparison of coaxial transceiving of a light spot formed at one side of the receiving device and a range of a light beam collected by the receiving device.

As shown in fig. 4, in the coaxial transmission/reception, the echo light spot 51 is a concentric ring that can cover only the range (shown by the area 52) where the light beam is collected by the receiving device. Wherein the collecting beam range of the receiving means is the area within the dashed circle in the figure, i.e. the area 52 in the figure.

When the area of the light beam collected by the receiving device is kept unchanged, the echo signal of the short-distance target is concentrated in the central area, and the echo light is shielded by the light splitting device in the coaxial transceiving system, for example, in the scheme of central reflection, the echo light is shielded by the light splitting device.

In addition, in the laser radar that employs coaxial transmission and reception, the presence of stray light also interferes with the echo light.

Referring to fig. 5, a schematic diagram of the optical path structure of another lidar is shown.

As shown in fig. 5, in the laser radar adopting the center reflection beam splitting method, the beam splitter 22 includes a beam splitting mirror. The light beam 21a generated by the emitting module 21 is reflected by the light splitting device 22 to form an emitting light 22a emitted to the three-dimensional space. The emitted light 22a is projected onto the target 20. The echo light 22b reflected by the target 20 is received by the receiving module 23 via the light splitting device 22. In order to control the interference, it is necessary to ensure that stray light from the transmission optical path, the light splitting device, and the reception optical path is as weak as possible.

However, as shown in fig. 5, for the light splitting reflector, a part of the light beam 21b generated by the emitting module 21 is reflected by the light splitting reflector near one end of the emitting module 21, so that stray light 22c is formed and is directly received by the receiving module 23. The signal of the stray light 22c is close to the echo signal formed by the near-distance target, and is difficult to detect and identify, so that the near-distance target is difficult to detect. Therefore, stray light formed by reflection of the light splitting device can cause strong interference on echo signals of the close-range target.

In order to solve the technical problem, the present invention provides a beam splitter, which is suitable for a laser radar for coaxial transmission and reception, and includes: the transmitting light of the laser radar forms echo light after being reflected by a target object; the light splitting device includes: a first region corresponding to a position of a light emitted from the lidar, the first region being for eliminating a blind area of the lidar; a second region surrounding the first region; when the first area reflects the emitted light to the target object, the transmissivity of the second area is not equal to that of the first area; or when the first area transmits the emitted light to the target object, the reflectivity of the second area is not equal to that of the first area.

According to the technical scheme, the light splitting device is provided with the first area, echo light shielded by the light splitting device can be effectively reduced, so that the intensity of the collected echo signal is improved, and the purposes of improving the near-field detection capability and reducing the near-field blind area are achieved.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Referring to fig. 6, there is shown a schematic structural view of an embodiment of the light splitting apparatus of the present invention,

the spectroscopic device 120 is applied to a laser radar that transmits and receives light coaxially, and the optical path of a part of the emitted light and the optical path of a part of the echo light are on the same optical axis. Specifically, the emitted light 111a of the laser radar is reflected by the target object 100 to form the return light 111b. Fig. 6 is a schematic diagram showing an optical path structure of a laser radar that uses coaxial transmission and reception according to an embodiment of the optical branching device of the present invention. In fig. 6, the part of the optical path downstream from the light splitting device 120 in the optical path of the emitted light is on the same optical axis as the part of the optical path upstream from the light splitting device 120 in the optical path of the echo light.

Referring to fig. 7, a schematic diagram of a front view structure of a light beam incident surface of the light splitting device 120 is shown.

The light splitting device includes:

a first area 121, the first area 121 corresponding to a position of the emitted light 111a of the lidar, the first area 121 being for eliminating a blind area of the lidar; a second region 122, said second region 122 surrounding said first region 121. The effect on the light beam by the second region 122 surrounding said first region 121 is different from the effect on the light beam by said first region 121.

In this embodiment, the lidar is a center reflection type coaxial transceiver lidar, that is, when the first region 121 reflects the emitting light 111a to the target 100, the transmittance of the second region 122 is not equal to the transmittance of the first region 121.

Specifically, as shown in fig. 6 and 7, when the first region 121 reflects the emitting light 111a to the target 100, the second region 122 transmits the echo light 111b, and in addition, the first region 121 transmits a part of the echo light 111b, so that the transmitted part of the echo light 111c is projected to the receiving module 130, thereby eliminating the laser radar blind area and realizing the blind compensation function.

In some embodiments of the present invention, when the first region 121 reflects the emitting light 111a to the target object 100, the transmittance of the second region 122 is greater than that of the first region 121. Specifically, the transmittance of the first region 121 is in the range of 2% to 10%; the second region 122 completely transmits the return light 111b, for example, the transmittance of the second region 122 is greater than 95%. By setting the transmittance of the first region 121 and the transmittance of the second region 122 within a reasonable range, the intensity of the echo signal of the near-distance target can be increased while the intensity of the emitted light is not affected as much as possible.

In this embodiment, the first region 121 of the light splitting device 120 has a transmittance of 2% to 10%, so that 2% to 10% of the echo light projected to the first region 121 can be transmitted, and then the echo light is collected by the receiving device 130, which is basically enough for blind compensation in short-distance ranging, so that the problem of weak echo signals of a short-distance target can be effectively solved.

With continued reference to fig. 6 and 7, in some embodiments of the present invention, the shape of the first region 121 is the same as the spot shape of the emitted light 111a on the surface of the light splitting device 120 in the plane of the beam incident surface of the light splitting device 122. The shape of the first region 121 is the same as the spot shape of the emitted light 111a, so that the area of the first region 121 can be controlled as much as possible, the influence of the first region 121 on the outgoing of the emitted light 111a is reduced as much as possible, and the long-range measuring capability of the laser radar is favorably ensured.

Specifically, the position and shape of the first region 121 of the light splitting device 120 are adjusted according to the lidar transmission/reception parameters, and are determined based on the spot shape and size of the emitted light 111 a.

Referring to fig. 8, the spot shape in the cross section of the emitted light 111a in the embodiment of the light splitting device shown in fig. 6 and the spot shape projected by the emitted light 111a onto the light splitting device 120 are shown.

In some embodiments of the present invention, the transmitting device 110 of the lidar includes a VCSEL laser, so that the light spot 111 in the cross section of the formed emitted light 111a is circular, i.e. L1= L2, where L1 and L2 are the lengths of two diameters orthogonal to the light spot 111, respectively. The light spot 123 projected on the light splitting device 120 by the emitting light 111a is an ellipse, wherein L1' = L1,

where α is an incident angle at which the emitted light 111a is projected onto the light splitting device 120.

Thus, the lidar comprises a VCSEL laser, and the shape of the first region 121 in the plane of the beam entrance surface of the spectroscopic assembly 120 is elliptical, i.e. the length of the first region 121 of the spectroscopic assembly 120 is L1'= L1 and the length of the major axis is L1' = L1, respectively

Is oval-shaped.

In other embodiments of the present invention, the transmitting device of the lidar includes an EEL laser, and the spot of the cross section of the formed emitted light is elliptical, and has a length L1 in the fast axis direction, a divergence angle of 2 × W1, a length L2 in the slow axis direction, a divergence angle of 2 × W2, and a divergence angle of W1>W2, after being collimated by the optical system, L1' = f tan W1, L2' = f tan W2, the spot of the emitted light projected onto the light splitting device is circular or approximately circular, L1= L1',

where α is the angle of incidence of the emitted light onto the light-splitting device.

Thus, the lidar comprises an EEL laser, the first area of the beam splitting device being circular in shape in the plane of the beam entrance surface of the beam splitting device, i.e. the first area of the beam splitting device is circular with equal length in the fast and slow axis direction.

In some embodiments of the present invention, the light splitting device is a special-shaped light splitting device, and with reference to fig. 9, an enlarged schematic structural diagram of the light splitting device in the embodiment of the light splitting device shown in fig. 6 is shown.

In this embodiment, the first region 121 of the light splitting device 120 reflects the emitting light 111a to the target 100; the light splitting device 120 includes an incident surface 124, a back surface 125, and a plurality of connection surfaces (connection surfaces 126a, connection surfaces 126b, etc.), wherein the incident surface 124 and the back surface 125 are disposed opposite to each other, the connection surfaces (connection surfaces 126a, connection surfaces 126b, etc.) are located between the incident surface 124 and the back surface 125, and the emitted light 111a is projected to the incident surface 124; a connection surface 126a of the transmitting module 110 (fig. 6) close to the lidar faces away from the receiving apparatus 130 of the lidar, in order to avoid that the emitted light 111d is deflected by the connection surface 126a to the receiving apparatus 130. Therefore, the light beam reflected by the connecting surface 126a toward the receiving module 130 of the laser radar is effectively reduced, so that the stray light can be suppressed, and the interference to the return light can be reduced.

As shown in fig. 9, an included angle between a normal direction of the connection surface 126a facing the transmitting module 110 and the direction vector of the echo light 111c is greater than or equal to 90 °, that is, an included angle between a normal direction of the connection surface 126a facing the transmitting module 110 and the direction vector of the echo light 111c is an obtuse angle, so that the normal direction of the connection surface 126a faces a direction away from the receiving apparatus 130 of the lidar.

Specifically, as shown in fig. 6, in the present embodiment, the optical axis of a part of the emitted light 111a is orthogonal to the optical axis of a part of the echo light 111c, and the emitted light is incident on the incident surface 124 at an angle θ; the angle between the connecting surface 126a facing the emitting module 110 and the normal negative direction of the incident surface 124 is greater than or equal to theta. As shown in fig. 9, an included angle β between the connection surface 126a facing the emission module 110 and the extending direction of the incident surface 124 is smaller than or equal to 45 °, where the angles θ and β are complementary angles, that is, the included angle between the connection surface 126a facing the emission module 110 and the normal negative direction of the incident surface 124 is greater than or equal to 45 °.

In addition, with reference to fig. 9, in this embodiment, the connection surface 126b facing away from the transmitting module 110 (as shown in fig. 6) is parallel to the echo light 111c, so as to reduce the projection area of the light splitting device 120 in a plane perpendicular to the optical axis of the echo light 111c as much as possible, thereby reducing the influence of the light splitting device 120 on the echo light 111 c.

It should be noted that, in this embodiment, the implementation that the optical splitting device is a special-shaped optical splitting device is only an example. In other embodiments of the present invention, the cross section of the light splitting device may also be a parallelogram.

Referring to fig. 10, there is shown a schematic structural diagram of another embodiment of the light splitting device of the present invention.

In this embodiment, the lidar is also a center reflection type coaxial transceiver lidar, i.e., the first region of the light splitting device 220 reflects the emitted light 211a. The present embodiment is the same as the previous embodiments, and the description of the present invention is omitted. The difference between this embodiment and the foregoing embodiment is that, in this embodiment, the laser radar further includes: a light-shielding sheet 240, the light-shielding sheet 240 being located on a path of the emitted light 111e transmitting the first region. The light shielding sheet 240 can absorb stray light, thereby reducing interference to echo signals.

The light-shielding sheet 240 is independently disposed downstream of an optical path of the emitted light 111e transmitting the first region, and a surface of the light-shielding sheet 240 is perpendicular to an optical axis of the emitted light 111 e.

It should be noted that the shape of the light shielding sheet 240 is mainly related to the spot shape and size of the emitted light 211a generated by the emitting device 210. The light shield 240 is sized to shield all residual emission light 211e transmitted by the light splitting device 220. In addition, the area of the light shielding sheet 240 is not too large to cover the area of the residual light 211e. Too large a size may result in a certain energy loss of the received return light 211c, and the larger the gobo, the larger the energy loss of the return light 211e. The light shielding sheet 240 is a thin sheet having a thickness as small as possible. In this embodiment, the thickness of the light shielding sheet 240 is less than 0.5mm.

Referring to fig. 11, a schematic structural diagram of a light splitting device according to still another embodiment of the present invention is shown.

The present embodiment is the same as the previous embodiments, and the description of the present invention is omitted. The difference between this embodiment and the previous embodiment is that in this embodiment, one end of the light shielding sheet 340 is fixedly connected to the light splitting device 320, for example, one end of the light shielding sheet 340 is bonded to a connecting surface of the light splitting device 320 facing away from the emitting device; the other end extends in a direction parallel to the echo light 311 c. By extending the light shielding sheet 340 in the direction parallel to the echo light 311c, the influence of the light shielding sheet 340 on the echo light 311c can be reduced as much as possible, and the area of the light shielding sheet 340 can be increased, thereby reducing the interference of the residual emitted light on the echo signal.

As shown in fig. 11, the other end of the light shielding sheet 340 extends to the receiving module 330 and contacts the receiving module 330. Specifically, referring to fig. 12 in combination, the receiving device 330 of the laser radar includes a receiving lens 331, and the other end of the light shielding plate 340 extends to the receiving lens 331 and contacts with the surface of the receiving lens 331. The other end of the light shielding sheet 340 is in contact with the receiving module 330, so that additional mechanical support can be provided for the light shielding sheet 340, the stability of the light shielding sheet 340 is ensured, the interference of mechanical vibration is reduced, especially in a vehicle-mounted laser radar, the influence of the vibration interference on a light path can be reduced, and the stability of the detection capability of the laser radar is improved. Moreover, the contact part between the light-shielding sheet 340 and the receiving lens 331 is made of soft material, such as rubber and silicone, to avoid mirror scratch.

Further, in the present embodiment, the size of the light-shielding sheet 340 is equal to the size of the receiving lens 331 in the height direction (indicated by arrow H in fig. 12), so that the height of the optical system may not be increased while height uniformity is easily fixed. The shape of the side surface of the light shielding plate 340 facing the receiving module 330 of the laser radar is adapted to the shape of the surface of the receiving lens 331 so as to surround the receiving lens 331.

Referring to fig. 13, a schematic structural diagram of a light splitting device according to still another embodiment of the present invention is shown.

The present embodiment is the same as the previous embodiments, and the description of the present invention is omitted. The difference between this embodiment and the previous embodiment is that in this embodiment, the lidar is a center-transmission type coaxial transceiver lidar, that is, as shown in fig. 13, when the first region of the light splitting device 420 transmits the emitting light 411a to the target object 400, the reflectivity of the second region is not equal to the reflectivity of the first region.

Specifically, the emitting light 411a generated by the emitting device 410 of the lidar transmits through the first region of the light splitting device 420 to form emitting light emitted toward the three-dimensional space; the emitted light is reflected by the target object 400 to form the echo light 411b, and the echo light 411b projected to the second area of the optical splitter 420 is completely reflected by the optical splitter 420 to the receiving device 430; the echo light 411b projected to the first zone is partially reflected by the first zone (as shown by beam 411c in fig. 13) to the receiving device 430.

In some embodiments of the present invention, when the first region 421 transmits the emitting light 411a to the target object 100, the reflectivity of the second region is greater than that of the first region. Specifically, the reflectivity of the first region is in the range of 2% -10%; the second region reflects the return light 411b completely, for example, the reflectivity of the second region is greater than 95%. The reflectivity of the first area and the reflectivity of the second area are set within a reasonable range, so that the intensity of an echo signal of a near-distance target can be improved while the intensity of emitted light is not influenced as much as possible.

In this embodiment, the first region of the light splitting device 420 has a reflectivity of 2% to 10%, so that 2% to 10% of the echo light projected to the first region can be reflected, and then the reflected echo light is collected by the receiving device 430, which is basically enough for blind compensation in short-distance measurement, so that the problem of weak echo signals of a short-distance target can be effectively solved.

Correspondingly, the invention also provides a laser radar.

Referring to fig. 6, a schematic diagram of an optical path structure of an embodiment of the lidar of the present invention is shown.

The laser radar includes: an emitting device 110, said emitting device 110 being adapted to generate said emitted light 111a; a receiving device 130, said receiving device 130 being adapted to receive said echo light 111c; a spectroscopic device 120, wherein the spectroscopic device 120 is a spectroscopic device of the present invention.

Because the light splitting device 120 is the light splitting device of the present invention, that is, the light splitting device has a first region and a second region, the light splitting device is provided with the first region, so that echo light blocked by the light splitting device 120 can be effectively reduced, echo signals collected by the laser radar are stronger, and the laser radar has higher near-field detection capability and smaller near-field blind area.

The optical splitting device 120 is the optical splitting device of the present invention, and therefore the specific technical solution of the optical splitting device 120 refers to the foregoing embodiment of the optical splitting device 120, and the present invention is not described herein again.

In this embodiment, the laser radar is a coaxial laser radar, that is, the emitted light 111a acted by the beam splitter 120 is coaxial with the echo light 111b. Specifically, the laser radar is a center reflection type laser radar which receives and transmits coaxially.

It should be further noted that, in this embodiment, the laser radar further includes: a rotating mirror (not shown in the figure), through which the emitted light 111b acted by the light splitting device 120 is reflected and emitted to a three-dimensional space; after being reflected by the rotating mirror, the echo light 111c is received by the receiving device 130 after being acted by the light splitting device 120. Specifically, the rotating mirror is located between the light splitting device 120 and the light outlet of the laser radar, and is used for scanning a target object in a three-dimensional space.

In summary, the first region and the second region have different effects on the light beam: when the first area reflects the emitted light to the target object, the transmissivity of the second area is not equal to that of the first area; or when the first area transmits the emitted light to the target object, the reflectivity of the second area is not equal to that of the first area, and the first area corresponding to the position of the laser radar emitted light is used for eliminating the blind area of the laser radar. Therefore, the light splitting device is provided with the first area, echo light shielded by the light splitting device can be effectively reduced, the intensity of collected echo signals is improved, and the purposes of improving the near field detection capability and reducing the near field blind area are achieved.

And, the transmittance of the first region is in the range of 2% to 10% when the first region reflects the emitted light; the first region has a reflectance in a range of 2% to 10% when the first region transmits the emitted light. The transmissivity or reflectivity of the first area is set within a reasonable range, so that the intensity of an echo signal of a near-distance target can be improved while the intensity of emitted light is not influenced as much as possible.

In addition, when the first region reflects the emitted light to the target object, the light splitting device comprises an incident surface, a back surface and a plurality of connecting surfaces, the incident surface and the back surface are arranged oppositely, the connecting surfaces are positioned between the incident surface and the back surface, and the emitted light is projected to the incident surface; and the connecting surface close to the transmitting module of the laser radar faces back to the receiving device of the laser radar. Because the connecting surface close to the transmitting module of the laser radar faces away from the receiving device of the laser radar, the reflected light beams of the receiving module of the laser radar with the connecting surface facing the laser radar are effectively reduced, and the aims of inhibiting stray light and reducing interference to echo light can be achieved.

In addition, when the first region reflects the emitted light to the target object, the light splitting device comprises an incident surface, a back surface and a plurality of connecting surfaces, the incident surface and the back surface are arranged oppositely, the connecting surfaces are positioned between the incident surface and the back surface, and the emitted light is projected to the incident surface; the connecting surface back to the emitting module is parallel to the echo light so as to reduce the influence of the light splitting device on the echo light as much as possible.

Further, when the first region reflects the emission light to the target object, the laser radar further includes: a light-shielding sheet located on an optical path of the emitted light that transmits the first region. The light shielding sheet can absorb stray light, so that interference on echo signals is reduced.

And furthermore, one end of the shading sheet is fixedly connected with the light splitting device, and the other end of the shading sheet extends along the direction parallel to the echo light. The direction of parallel echo light is extended to the messenger, can minimize the influence of anti-dazzling screen setting to echo light to guarantee echo signal intensity, guarantee detectivity.

In addition, one end of the light shielding sheet is fixedly connected with the light splitting device, and the other end of the light shielding sheet extends along the direction parallel to the echo light; and the receiving module of the laser radar comprises a receiving lens, and the other end of the shading sheet extends to the receiving lens and is in contact with the surface of the receiving lens. The other end of the light shielding sheet is in contact with the surface of the receiving lens, so that the light shielding sheet can provide additional mechanical support, the stability of the light shielding sheet is guaranteed, the interference of mechanical vibration is reduced, especially in a vehicle-mounted laser radar, the influence of the vibration interference on a light path can be reduced, and the stability of the detection capability of the laser radar is improved.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A beam splitter device, which is suitable for use in a laser radar for coaxial transmission and reception,

the transmitting light of the laser radar forms echo light after being reflected by a target object;

the light splitting device includes:

a first region corresponding to a position of a light emitted from the lidar, the first region being for eliminating a blind area of the lidar;

a second region surrounding the first region;

when the first area reflects the emitted light to the target object, the transmissivity of the second area is not equal to the transmissivity of the first area;

or when the first area transmits the emitted light to the target object, the reflectivity of the second area is not equal to the reflectivity of the first area.

2. The light-splitting device according to claim 1, wherein when said first region reflects said emission light to said target, said first region transmits a part of said echo light, and said second region transmits said echo light.

3. The light-splitting apparatus according to claim 2, wherein a transmittance of the second region is greater than a transmittance of the first region.

4. A spectroscopic device according to any one of claims 1 to 3 wherein the first region has a transmittance in the range of 2% to 10%.

5. The spectroscopic apparatus according to claim 1, wherein when the first region transmits the emission light to the target, the first region partially reflects the echo light, and the second region reflects the echo light.

6. The light-splitting apparatus of claim 4, wherein the reflectivity of the second region is greater than the reflectivity of the first region.

7. The light-splitting device of claim 1, 5, or 6, wherein the reflectance of the first region is in the range of 2% to 10%.

8. The light-splitting device according to claim 1, wherein the shape of the first region is the same as the spot shape of the emitted light on the light-splitting device surface in the plane of the light-splitting device light-beam incident surface.

9. The beam splitting device of claim 8, wherein the lidar includes a VCSEL laser, and wherein the first region is elliptical in shape in a plane of a beam incident surface of the beam splitting device;

or the laser radar includes an EEL laser, and the shape of the first area is circular in the plane of the beam incident surface of the beam splitting device.

10. The light-splitting device according to claim 1, wherein when the first region reflects the emitted light toward the target, the light-splitting device comprises an incident surface, a back surface, and a plurality of connecting surfaces, the incident surface and the back surface being disposed opposite to each other, the connecting surfaces being located between the incident surface and the back surface, the emitted light being projected toward the incident surface;

and the connecting surface facing the transmitting module of the laser radar faces back to the receiving device of the laser radar.

11. The light-splitting device according to claim 10, wherein an angle between a normal direction to a connection surface of the emission module and a direction vector of the echo light is greater than or equal to 90 °.

12. The spectroscopic apparatus according to claim 11, wherein an optical axis of a part of the emitted light is orthogonal to an optical axis of a part of the echo light, the emitted light being incident on the incident surface at an angle θ;

and the included angle between the connecting surface facing the transmitting module and the normal negative direction of the incident surface is greater than or equal to theta.

13. The light-splitting device according to claim 1, wherein when the first region reflects the emitted light toward the target, the light-splitting device comprises an incident surface, a back surface, and a plurality of connecting surfaces, the incident surface and the back surface being disposed opposite to each other, the connecting surfaces being located between the incident surface and the back surface, the emitted light being projected toward the incident surface;

the connecting surface back to the emitting module is parallel to the echo light.

14. The spectroscopic apparatus of claim 1 wherein, when the first region reflects the emitted light to the target object, the lidar further comprises: a light-shielding sheet on a path of the emitted light transmitting the first region.

15. The beam splitting device as claimed in claim 14, wherein one end of the light shielding plate is fixedly connected to the beam splitting device, and the other end extends in a direction parallel to the echo light.

16. The beam splitting device according to claim 14, wherein the receiving device of the laser radar includes a receiving lens, and the other end of the shutter extends to the receiving lens to be in contact with a surface of the receiving lens.

17. The beam splitting apparatus according to claim 16, wherein a side surface of the louver on a side facing a receiving module of the laser radar has a shape corresponding to a surface shape of the receiving lens.

18. The light-splitting device according to claim 16, wherein a dimension of the light-shielding sheet is equal to a dimension of the receiving lens in a height direction orthogonal to both the emitted light and the echo light.

19. A lidar characterized by comprising:

an emitting device adapted to generate the emitted light;

a receiving device adapted to receive the echo light;

a spectroscopic apparatus according to any one of claims 1 to 18.

20. The lidar of claim 19, wherein said emitted light acted upon by said beam splitting means is coaxial with said return light.

21. The lidar of claim 19, further comprising: the transmitted light acted by the light splitting device is reflected by the rotating mirror and then is emitted to a three-dimensional space; after the reflection of the rotating mirror, the echo light is received by the receiving device after the action of the light splitting device.