Spectroscopic device and lidar

Abstract

The application discloses a light splitting device and a laser radar. The light splitting device is suitable for a laser radar for coaxial transmission and reception, and comprises: echo light formed by transmitting light of the laser radar after reflection of a target object; the light splitting device comprises: a first area corresponding to a position of the transmitting light of the laser radar, the first area being used for eliminating a blind area of the laser radar; and a second area surrounding the first area; when the first area reflects the transmitting light to the target object, a transmittance of the second area is not equal to a transmittance of the first area; or when the first area transmits the transmitting light to the target object, a reflectivity of the second area is not equal to a reflectivity of the first area. The light splitting device is provided with the first area, echo light blocked by the light splitting device can be effectively reduced, collected echo signal strength can be improved, and near field detection capability of the laser radar can be improved and a near field blind area can be reduced.

Description

Technical Field

[0001] This invention relates to the field of laser detection, and in particular to a beam splitting device and a lidar. Background Technology

[0002] LiDAR is a commonly used ranging sensor, characterized by its long detection range, high resolution, and low susceptibility to environmental interference. It is widely used in intelligent robots, drones, and autonomous driving. In recent years, with the rapid development of autonomous driving technology, LiDAR, as a core sensor for distance perception, has become indispensable.

[0003] Depending on the layout of the transmitting and receiving optical paths, lidar can be divided into non-coaxial and coaxial types. In non-coaxial lidar, the transmitting and receiving optical paths are independent and are usually implemented using different mirror groups, which respectively undertake the functions of laser transmission and reception. In coaxial lidar, the transmitting and receiving optical paths share the same optical axis and often share a single transceiver mirror group. The separation and recombination of the transmitting and receiving beams are achieved through beam splitting elements (such as beam splitters, pinhole mirrors, etc.).

[0004] Non-coaxial transceivers require independent transmitting and receiving modules, which often results in larger size and less compact structure of lidar. In addition, non-coaxial transceivers also have the problems of complex assembly and adjustment and higher cost.

[0005] However, existing lidar systems that use coaxial transceivers often have weak near-field detection capabilities and a large near-field blind zone. Summary of the Invention

[0006] The problem solved by this invention is to provide a beam splitting device and a lidar to improve the detection capability of close-range targets.

[0007] To address the above problems, the present invention provides a beam splitter, which is suitable for coaxial transceiver lidar, comprising:

[0008] The emitted light from the lidar is reflected by the target object to form an echo light; the beam splitter includes: a first region, which corresponds to the position of the emitted light from the lidar and is used to eliminate the blind zone of the lidar; and a second region, which surrounds the first region; when the first region reflects the emitted light to the target object, the transmittance of the second region is not equal to the transmittance of the first region; or when the first region transmits the emitted light to the target object, the reflectance of the second region is not equal to the reflectance of the first region.

[0009] Optionally, when the first region reflects the emitted light to the target object, the first region transmits a portion of the echo light, and the second region transmits the echo light.

[0010] Optionally, the transmittance of the second region is greater than that of the first region.

[0011] Optionally, the transmittance of the first region is in the range of 2% to 10%.

[0012] Optionally, when the first region transmits the emitted light to the target object, the first region partially reflects the echo light, and the second region reflects the echo light.

[0013] Optionally, the reflectivity of the second region is greater than that of the first region.

[0014] Optionally, the reflectivity of the first region is in the range of 2% to 10%.

[0015] Optionally, within the plane of the beam incident surface of the beam splitter, the shape of the first region is the same as the shape of the emitted light spot on the surface of the beam splitter.

[0016] Optionally, the lidar includes a VCSEL laser, and the first region is elliptical in shape within the plane of the beam incident surface of the beam splitter; or the lidar includes an EEL laser, and the first region is circular in shape within the plane of the beam incident surface of the beam splitter.

[0017] Optionally, when the first region reflects the emitted light to the target, the beam splitting device includes an incident surface, a back surface, and multiple connecting surfaces. The incident surface and the back surface are arranged opposite to each other, and the connecting surfaces are located between the incident surface and the back surface. The emitted light is projected onto the incident surface; the connecting surfaces facing the transmitting module of the lidar face away from the receiving device of the lidar.

[0018] Optionally, the angle between the normal direction of the connection surface of the transmitting module and the direction vector of the echo light is greater than or equal to 90°.

[0019] Optionally, the optical axis of a portion of the emitted light is orthogonal to the optical axis of a portion of the echo light, and the emitted light is incident on the incident surface at an angle θ; the angle between the connecting surface toward the emitting module and the negative normal direction of the incident surface is greater than or equal to θ.

[0020] Optionally, when the first region reflects the emitted light to the target object, the beam splitter includes an incident surface, a back surface, and multiple connecting surfaces. The incident surface and the back surface are arranged opposite to each other, and the connecting surfaces are located between the incident surface and the back surface. The emitted light is projected onto the incident surface; the connecting surfaces facing away from the emission module are parallel to the echo light.

[0021] Optionally, when the first region reflects the emitted light to the target, the lidar further includes a light-shielding plate located on the path of the emitted light that transmits through the first region.

[0022] Optionally, one end of the light-shielding plate is fixedly connected to the beam splitter, and the other end extends in a direction parallel to the echo light.

[0023] Optionally, the receiving device of the lidar includes a receiving lens, and the other end of the light-shielding plate extends to the receiving lens and contacts the surface of the receiving lens.

[0024] Optionally, the shape of the side of the light-shielding plate facing the receiving module of the lidar is adapted to the surface shape of the receiving lens.

[0025] Optionally, in the height direction, the size of the light-shielding plate is equal to the size of the receiving lens, and the height direction is orthogonal to both the emitted light and the echo light.

[0026] Accordingly, the present invention also provides a lidar, comprising:

[0027] A transmitting device adapted to generate the emitted light; a receiving device adapted to receive the echo light; and a beam splitter, wherein the beam splitter is the beam splitter of the present invention.

[0028] Optionally, the emitted light after being processed by the beam splitter is coaxial with the echo light.

[0029] Optionally, it also includes: a rotating mirror, wherein the emitted light, after being acted upon by the beam splitter, is reflected by the rotating mirror and emitted into three-dimensional space; and the echo light, after being reflected by the rotating mirror, is received by the receiving device after being acted upon by the beam splitter.

[0030] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0031] In this invention, the first region and the second region have different effects on the light beam: when the first region reflects the emitted light to the target, the transmittance of the second region is not equal to that of the first region; or when the first region transmits the emitted light to the target, the reflectance of the second region is not equal to that of the first region. The first region, corresponding to the position of the emitted light from the lidar, is used to eliminate the blind zone of the lidar. Therefore, by setting the first region in the beam splitter, the echo light blocked by the beam splitter can be effectively reduced, thereby increasing the intensity of the collected echo signal and achieving the purpose of improving near-field detection capability and reducing near-field blind zone.

[0032] In an optional embodiment of the present invention, when the first region reflects the emitted light, the transmittance of the first region is in the range of 2% to 10%; when the first region transmits the emitted light, the reflectance of the first region is in the range of 2% to 10%. Setting the transmittance or reflectance of the first region within a reasonable range can improve the echo signal strength of near-range targets while minimizing the impact on the emitted light intensity.

[0033] In an optional embodiment of the present invention, when the emitted light is reflected from the first region to the target object, the beam splitting device includes an incident surface, a back surface, and multiple connecting surfaces. The incident surface and the back surface are arranged opposite to each other, and the connecting surfaces are located between the incident surface and the back surface. The emitted light is projected onto the incident surface. The connecting surface near the transmitting module of the lidar faces away from the receiving device of the lidar. Because the connecting surface near the transmitting module of the lidar faces away from the receiving device of the lidar, the beam reflected from the connecting surface towards the receiving module of the lidar is effectively reduced, thereby achieving the purpose of suppressing stray light and reducing interference with the echo light.

[0034] In an optional embodiment of the present invention, when the first region reflects the emitted light to the target object, the beam splitter includes an incident surface, a back surface, and multiple connecting surfaces. The incident surface and the back surface are arranged opposite to each other, and the connecting surfaces are located between the incident surface and the back surface. The emitted light is projected onto the incident surface. The connecting surfaces facing away from the emission module are parallel to the echo light to minimize the influence of the beam splitter on the echo light.

[0035] In an optional embodiment of the present invention, when the emitted light is reflected from the first region to the target object, the lidar further includes a light-shielding plate located on the optical path through which the emitted light from the first region is transmitted. The light-shielding plate can absorb stray light, thereby reducing interference with the echo signal.

[0036] In an optional embodiment of the present invention, one end of the light-shielding plate is fixedly connected to the beam splitter, and the other end extends in a direction parallel to the echo light. Extending in a direction parallel to the echo light minimizes the impact of the light-shielding plate's placement on the echo light, thereby ensuring the echo signal strength and detection capability.

[0037] In an optional embodiment of the present invention, one end of the light-shielding plate is fixedly connected to the beam splitter, and the other end extends in a direction parallel to the echo light; and the receiving module of the lidar includes a receiving lens, with the other end of the light-shielding plate extending to the receiving lens and contacting the surface of the receiving lens. The contact between the other end of the light-shielding plate and the surface of the receiving lens provides additional mechanical support for the light-shielding plate, ensuring its stability and reducing interference from mechanical vibrations. Particularly in vehicle-mounted lidar, this reduces the impact of vibration interference on the optical path and improves the stability of the lidar's detection capability. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the optical path structure of a lidar.

[0039] Figure 2 yes Figure 1 The diagram shows the optical path of a lidar for detecting near-range and far-range targets.

[0040] Figure 3 yes Figure 1 The diagram shows the shape of the echo light spot during coaxial transmission and reception on one side of the receiving device of the lidar.

[0041] Figure 4 It is a comparison between the light spot formed by the coaxial transceiver on one side of the receiving device and the range of the beam collected by the receiving device;

[0042] Figure 5 This is a schematic diagram of the optical path structure of another type of lidar;

[0043] Figure 6 This is a schematic diagram of the structure of an embodiment of the beam splitting device of the present invention;

[0044] Figure 7 yes Figure 6 A schematic diagram of the front view of the beam incident surface in the embodiment of the beam splitting device shown;

[0045] Figure 8 yes Figure 6 The shape of the light spot within the cross-section of the emitted light in the illustrated beam splitter embodiment is the same as the shape of the light spot projected onto the beam splitter by the emitted light.

[0046] Figure 9 yes Figure 6 A cross-sectional structural schematic diagram of an embodiment of the beam splitter shown;

[0047] Figure 10 This is a schematic diagram of another embodiment of the beam splitting device of the present invention;

[0048] Figure 11 This is a schematic diagram of another embodiment of the beam-splitting device of the present invention;

[0049] Figure 12 yes Figure 11 A schematic diagram of the structure of the light-shielding plate and the receiving lens in the example of the beam-splitting device of the present invention;

[0050] Figure 13 This is a schematic diagram of another embodiment of the spectrophotometer of the present invention. Detailed Implementation

[0051] As the background technology shows, existing lidar technologies using coaxial transceivers often suffer from weak near-field detection capabilities. This paper analyzes the reasons for this weak detection capability using the optical path structure of a particular lidar:

[0052] refer to Figure 1 The diagram shows a schematic of the optical path structure of a lidar.

[0053] The lidar is a coaxial transceiver lidar. The coaxial transceiver used in this lidar includes a beam splitting method based on center reflection. Figure 1 The central reflection method of beam splitting will be used as an example for explanation.

[0054] like Figure 1 As shown, the beam 11a generated by the transmitting module 11 is reflected by the beam splitter 12 to form the emitted light 12a that is emitted toward three-dimensional space. The emitted light 12a is reflected by the target object 10 to form the echo light 12b that is projected onto the receiving module 13.

[0055] Coaxial transceiver schemes with center reflection all suffer from weak echo signals at close range. The main reason for this is the obstruction of the echo light from nearby targets.

[0056] refer to Figure 2 , showed Figure 1 The diagram shows the optical path of a lidar for detecting near-range and far-range targets.

[0057] For lidar, especially vehicle-mounted lidar, long-range measurement is a crucial performance indicator. Therefore, the optical path of the lidar optical system (mainly composed of optical components such as lenses or lens groups) is designed primarily for distant targets 21, and the focal length of the optical system is also set for distant targets 21. However, when detecting close-range targets 22, the lidar optical system is often out of focus, and the closer the target is, the greater the proportion of echo light that is blocked; the weaker the echo light intensity, the lower the target detection probability.

[0058] like Figure 2 As shown, Figure 1 In a coaxial transceiver using a central reflection method, region 24 (i.e. Figure 2The emitted light (within the dashed elliptical region) is reflected; the near-range target 22 reflects the emitted light to form an echo light spot 23; the echo light can only be collected by the receiving device in areas outside region 24. Specifically, such as... Figure 3 As shown, on the receiving side, during coaxial transmission and reception, the echo light spot is a concentric ring, and the blank area in the center corresponds to the position of the reflected emitted light. Figure 3 (Location shown in central area 31).

[0059] Reference Figure 4 ,in Figure 4 It is a comparison between the light spot formed by the coaxial transceiver on one side of the receiving device and the range of the beam collected by the receiving device.

[0060] like Figure 4 As shown, in coaxial transmission and reception, the echo light spot 51 is a concentric ring that can only cover part of the beam range collected by the receiving device (as shown in region 52 in the figure). The beam range collected by the receiving device is the area inside the dashed circle in the figure, i.e., region 52 in the figure.

[0061] When the area of ​​the beam collected by the receiving device remains unchanged, the echo signal of the near target is concentrated in the central region. The echo light is blocked by the beam splitter in the coaxial transceiver system, for example, in the central reflection scheme.

[0062] In addition, in lidar that uses coaxial transceivers, the presence of stray light can also interfere with the echo light.

[0063] refer to Figure 5 This shows a schematic diagram of the optical path structure of another type of lidar.

[0064] like Figure 5 In a lidar system employing a central reflection beam splitting method, the beam splitting device 22 includes a beam splitting mirror. The beam 21a generated by the transmitting module 21 is reflected by the beam splitting device 22 to form emitted light 22a projected into three-dimensional space. The emitted light 22a is projected onto the target object 20. The echo light 22b reflected by the target object 20 is received by the receiving module 23 via the beam splitting device 22. To control interference, stray light from the transmitting optical path—beam splitting device—receiving optical path needs to be as weak as possible.

[0065] However, as Figure 5As shown, for the beam-splitting mirror, the end closer to the transmitting module 21 reflects a portion of the beam 21b generated by the transmitting module 21, thus forming stray light 22c which is directly received by the receiving module 23. The signal of the stray light 22c is close to the echo signal generated by the nearby target, making it difficult to detect and identify, and thus hindering the detection of nearby targets. It is evident that the stray light reflected by the beam-splitting device causes strong interference to the echo signal of nearby targets.

[0066] To solve the aforementioned technical problem, the present invention provides a beam splitting device suitable for coaxial transceiver lidar, comprising: the lidar's emitted light being reflected by a target object to form echo light; the beam splitting device comprising: a first region corresponding to the position of the lidar's emitted light, the first region being used to eliminate the lidar's blind zone; a second region surrounding the first region; when the first region reflects the emitted light to the target object, the transmittance of the second region is not equal to the transmittance of the first region; or when the first region transmits the emitted light to the target object, the reflectance of the second region is not equal to the reflectance of the first region.

[0067] According to the technical solution of the present invention, the beam splitting device is set in the first region, which can effectively reduce the echo light blocked by the beam splitting device, thereby increasing the intensity of the collected echo signal, and thus achieving the purpose of improving near-field detection capability and reducing near-field blind zone.

[0068] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0069] refer to Figure 6 The diagram shows a structural schematic of an embodiment of the beam-splitting device of the present invention.

[0070] It should be noted that the beam splitter 120 is suitable for coaxial transceiver lidar, where the optical paths of part of the emitted light and part of the echo light are on the same optical axis. Specifically, the emitted light 111a of the lidar is reflected by the target object 100 to form echo light 111b. Figure 6 The diagram shows a schematic of the optical path structure of a lidar using a coaxial transceiver according to an embodiment of the beam splitting device of the present invention. Figure 6 In the emitted light path, a portion of the optical path downstream of the beam splitter 120 is on the same optical axis as a portion of the optical path upstream of the beam splitter 120 in the echo light path.

[0071] Reference Figure 7 The diagram shows a front view of the beam incident surface of the beam splitter 120.

[0072] The beam splitter includes:

[0073] The first region 121 corresponds to the position of the emitted light 111a of the lidar and is used to eliminate the blind zone of the lidar. The second region 122 surrounds the first region 121. The effect of the second region 122 surrounding the first region 121 on the light beam is different from the effect of the first region 121 on the light beam.

[0074] In this embodiment, the lidar is a center-reflection coaxial transceiver lidar, that is, when the first region 121 reflects the emitted light 111a to the target object 100, the transmittance of the second region 122 is not equal to the transmittance of the first region 121.

[0075] Specifically, such as Figure 6 and Figure 7 As shown, when the first region 121 reflects the emitted light 111a to the target object 100, the second region 122 transmits the echo light 111b. In addition, the first region 121 transmits part of the echo light 111b so that the transmitted part of the echo light 111c is projected onto the receiving module 130, thereby eliminating the blind spot of the lidar and achieving the blind spot compensation function.

[0076] In some embodiments of the present invention, when the first region 121 reflects the emitted 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 echo light 111b, for example, the transmittance of the second region 122 is greater than 95%. Setting the transmittance of the first region 121 and the second region 122 within a reasonable range can improve the echo signal strength of the near-range target while minimizing the impact on the emitted light intensity.

[0077] In this embodiment, the first region 121 of the beam splitter 120 has a transmittance of 2% to 10%. Therefore, 2% to 10% of the echo light projected onto the first region 121 can be transmitted and collected by the receiving device 130. This is basically sufficient for blind spot compensation in close-range ranging, thereby effectively solving the problem of weak echo signals from close-range targets.

[0078] Continue to refer to Figure 6 and Figure 7In some embodiments of the present invention, within the plane of the beam incident surface of the beam splitter 122, the shape of the first region 121 is the same as the shape of the light spot of the emitted light 111a on the surface of the beam splitter 120. Making the shape of the first region 121 the same as the light spot shape of the emitted light 111a allows for better control of the area of ​​the first region 121, minimizing its influence on the emission of the emitted light 111a, and thus helping to ensure the range-finding capability of the lidar.

[0079] Specifically, the position and shape of the first region 121 of the beam splitter 120 are adjusted according to the laser radar transceiver parameters, and are mainly determined based on the shape and size of the light spot of the emitted light 111a.

[0080] refer to Figure 8 , showed Figure 6 The shape of the light spot in the cross-section of the emitted light 111a in the embodiment of the beam splitter shown is the same as the shape of the light spot projected by the emitted light 111a onto the beam splitter 120.

[0081] In some embodiments of the present invention, the emitting device 110 of the lidar includes a VCSEL laser, so the light spot 111 within the cross-section of the emitted light 111a is circular, i.e., L1 = L2, where L1 and L2 are the lengths of two orthogonal diameters of the light spot 111. The light spot 123 projected by the emitted light 111a onto the beam splitter 120 is elliptical, where L1' = L1, Wherein, α is the incident angle of the emitted light 111a projected onto the beam splitter 120.

[0082] Therefore, the lidar includes a VCSEL laser, and within the plane of the beam incident surface of the beam splitter 120, the first region 121 is elliptical in shape, that is, the first region 121 of the beam splitter 120 has a minor axis length and a major axis length of L1' = L1 and L2, respectively. It is an oval shape.

[0083] In other embodiments of the present invention, the transmitting device of the lidar includes an EEL laser, and the light spot in the cross-section of the emitted light is elliptical, with a length of L1 along the fast axis and a divergence angle of 2*W1, and a length of L2 along the slow axis and a divergence angle of 2*W2, where W1>W2. After collimation by the optical system, L1′=f*tan W1, L2′=f*tan W2. The light spot projected onto the beam splitter is circular or approximately circular, and L1″=L1′. Where α is the incident angle of the emitted light projected onto the beam splitter.

[0084] Therefore, the lidar includes an EEL laser, and the first region is circular in shape within the plane of the beam incident surface of the beam splitter, that is, the first region of the beam splitter is a circle with equal length in the fast axis direction and the slow axis direction.

[0085] In some embodiments of the present invention, the beam splitter is an irregularly shaped beam splitter, in conjunction with reference to the reference. Figure 9 , showed Figure 6 The diagram shows an enlarged view of the beam splitter in the embodiment shown.

[0086] In this embodiment, the first region 121 of the beam splitter 120 reflects the emitted light 111a to the target object 100; the beam splitter 120 includes an incident surface 124, a back surface 125, and multiple connecting surfaces (connecting surfaces 126a, 126b, etc.), the incident surface 124 and the back surface 125 are arranged opposite to each other, the connecting surfaces (connecting surfaces 126a, 126b, etc.) are located between the incident surface 124 and the back surface 125, and the emitted light 111a is projected onto the incident surface 124; the emitting module 110 near the lidar (e.g., Figure 6 The connecting surface 126a (as shown) faces away from the receiving device 130 of the lidar to prevent the emitted light 111d from being deflected by the connecting surface 126a to the receiving device 130. Therefore, the reflected beam from the connecting surface 126a towards the receiving module 130 of the lidar is effectively reduced, thereby achieving the purpose of suppressing stray light and reducing interference with the echo light.

[0087] like Figure 9 As shown, the angle between the normal direction of the connecting 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, the angle between the normal direction of the connecting 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 connecting surface 126a is directed away from the receiving device 130 of the lidar.

[0088] Specifically, such as Figure 6 As shown, in this embodiment, the optical axis of a portion of the emitted light 111a is orthogonal to the optical axis of a portion 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 towards the emitting module 110 and the negative normal direction of the incident surface 124 is greater than or equal to θ. Figure 9 As shown, the angle β between the connecting surface 126a towards the transmitting module 110 and the extending direction of the incident surface 124 is less than or equal to 45°, where angles θ and β are complementary angles, that is, the angle between the connecting surface 126a towards the transmitting module 110 and the negative direction of the normal of the incident surface 124 is greater than or equal to 45°.

[0089] In addition, continue to refer to Figure 9 In this embodiment, the transmitter module 110 is facing away from the transmitter module 110 (e.g., Figure 6 The connecting surface 126b (as shown) is parallel to the echo light 111c to minimize the projected area of ​​the beam splitter 120 in the plane perpendicular to the optical axis of the echo light 111c, thereby reducing the influence of the beam splitter 120 on the echo light 111c.

[0090] It should be noted that, in this embodiment, the use of an irregularly shaped beam splitter is merely an example. In other embodiments of the present invention, the cross-section of the beam splitter may also be a parallelogram.

[0091] refer to Figure 10 The diagram shows a structural schematic of another embodiment of the beam splitting device of the present invention.

[0092] In this embodiment, the lidar is also a center-reflection coaxial transceiver lidar, that is, the first region of the beam splitter 220 reflects the emitted light 211a. The similarities between this embodiment and the previous embodiments will not be repeated here. The difference between this embodiment and the previous embodiments is that in this embodiment, the lidar further includes a light-shielding plate 240, which is located on the path of the emitted light 111e transmitted through the first region. The light-shielding plate 240 can absorb stray light, thereby reducing interference to the echo signal.

[0093] The light-shielding plate 240 is independently disposed downstream of the optical path of the emitted light 111e that transmits the first region, and the surface of the light-shielding plate 240 is perpendicular to the optical axis of the emitted light 111e.

[0094] It should be noted that the shape of the light-shielding plate 240 is mainly related to the shape and size of the light spot of the emitted light 211a generated by the emitting device 210. The size of the light-shielding plate 240 needs to block all residual emitted light 211e transmitted by the beam splitter 220. In addition, the area of ​​the light-shielding plate 240 should not be too large, just enough to cover the area of ​​the residual emitted light 211e. If the size is too large, it will cause some energy loss in the received echo light 211c; the larger the light-shielding plate, the greater the energy loss of the echo light 211e. The light-shielding plate 240 is a thin sheet, and its thickness should be as small as possible. In this embodiment, the thickness of the light-shielding plate 240 is less than 0.5 mm.

[0095] refer to Figure 11 The diagram shows a structural schematic of another embodiment of the spectral splitting device of the present invention.

[0096] The similarities between this embodiment and the previous embodiments are not repeated here. The difference between this embodiment and the previous embodiments is that in this embodiment, one end of the light-shielding plate 340 is fixedly connected to the beam splitter 320; for example, one end of the light-shielding plate 340 is bonded to the connecting surface of the beam splitter 320 facing away from the transmitting device; the other end extends in a direction parallel to the echo light 311c. Extending the light-shielding plate 340 in a direction parallel to the echo light 311c minimizes the influence of the light-shielding plate 340 on the echo light 311c, while simultaneously increasing the area of ​​the light-shielding plate 340, thereby reducing the interference of residual emitted light on the echo signal.

[0097] like Figure 11 As shown, the other end of the light-shielding plate 340 extends to and contacts the receiving module 330. Specifically, refer to the reference... Figure 12 The receiving device 330 of the lidar includes a receiving lens 331, and the other end of the light-shielding plate 340 extends to the receiving lens 331 and contacts the surface of the receiving lens 331. This contact between the other end of the light-shielding plate 340 and the receiving module 330 provides additional mechanical support for the light-shielding plate 340, ensuring its stability and reducing interference from mechanical vibrations. This is particularly beneficial in automotive lidar systems, reducing the impact of vibration interference on the optical path and improving the stability of the lidar's detection capabilities. Furthermore, the portion of the light-shielding plate 340 that contacts the receiving lens 331 is made of a soft material, such as rubber or silicone, to prevent scratches on the lens surface.

[0098] Furthermore, in this embodiment, in the height direction ( Figure 12 As indicated by the middle arrow H, the size of the light-shielding plate 340 is equal to the size of the receiving lens 331, thus not increasing the height of the optical system, and the consistent height makes it easy to fix. Moreover, the side shape of the light-shielding plate 340 facing the receiving module 330 of the lidar is adapted to the surface shape of the receiving lens 331 to surround the receiving lens 331.

[0099] refer to Figure 13 The diagram shows a structural schematic of another embodiment of the spectral splitting device of the present invention.

[0100] The similarities between this embodiment and the previous embodiments are not repeated here. The difference between this embodiment and the previous embodiments is that, in this embodiment, the lidar is a center-transmitting coaxial transceiver lidar, i.e., as shown... Figure 13 As shown, when the emitted light 411a is transmitted from the first region of the beam splitter 420 to the target object 400, the reflectivity of the second region is not equal to that of the first region.

[0101] Specifically, the emitted light 411a generated by the laser radar's transmitting device 410 is transmitted through the first region of the beam splitter 420 to form emitted light oriented towards three-dimensional space; the emitted light is reflected by the target object 400 to form echo light 411b, and the echo light 411b projected onto the second region of the beam splitter 420 is completely reflected by the beam splitter 420 to the receiving device 430; the echo light 411b projected onto the first region is partially reflected by the first region (e.g., ...). Figure 13 The beam 411c is directed to the receiving device 430.

[0102] In some embodiments of the present invention, when the first region 421 transmits the emitted 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% to 10%; the second region completely reflects the echo light 411b, for example, the reflectivity of the second region is greater than 95%. Setting the reflectivity of the first region and the second region within a reasonable range can improve the echo signal strength of the near-range target while minimizing the impact on the emitted light intensity.

[0103] In this embodiment, the first region of the beam splitter 420 has a reflectivity of 2% to 10%, so 2% to 10% of the echo light projected onto the first region can be reflected and then collected by the receiving device 430. This is basically sufficient for blind spot compensation in close-range ranging, thereby effectively solving the problem of weak echo signals from close-range targets.

[0104] Accordingly, the present invention also provides a lidar.

[0105] refer to Figure 6 The diagram shows a schematic of the optical path structure of an embodiment of the lidar of the present invention.

[0106] The lidar includes: a transmitting device 110 adapted to generate the emitted light 111a; a receiving device 130 adapted to receive the echo light 111c; and a beam splitter 120, which is the beam splitter of the present invention.

[0107] Since the beam splitter 120 is the beam splitter of the present invention, that is, the beam splitter has a first region and a second region, the beam splitter is set with the first region, which can effectively reduce the echo light blocked by the beam splitter 120. The echo signal collected by the lidar is stronger, and the lidar has a higher near-field detection capability and a smaller near-field blind zone.

[0108] The beam splitter 120 is the beam splitter of the present invention. Therefore, the specific technical solution of the beam splitter 120 can be referred to the aforementioned embodiment of the beam splitter 120. The present invention will not be described again here.

[0109] It should be noted that in this embodiment, the lidar is a coaxial lidar, meaning that the emitted light 111a and the echo light 111b, after being processed by the beam splitter 120, are coaxial. Specifically, the lidar is a coaxial transceiver lidar using a center-reflection type.

[0110] It should also be noted that in this embodiment, the lidar further includes a rotating mirror (not shown in the figure), through which the emitted light 111b, after being acted upon by the beam splitter 120, is reflected and emitted into three-dimensional space; and after being reflected by the rotating mirror, the echo light 111c, after being acted upon by the beam splitter 120, is received by the receiving device 130. Specifically, the rotating mirror is located between the beam splitter 120 and the light output port of the lidar, and is used to scan targets in three-dimensional space.

[0111] In summary, the first and second regions have different effects on the light beam: when the first region reflects the emitted light to the target, the transmittance of the second region is not equal to that of the first region; or when the first region transmits the emitted light to the target, the reflectance of the second region is not equal to that of the first region. The first region, corresponding to the position of the emitted light from the lidar, is used to eliminate the blind zone of the lidar. Therefore, by setting the first region in the beam splitter, the echo light blocked by the beam splitter can be effectively reduced, thereby increasing the intensity of the collected echo signal and thus achieving the purpose of improving near-field detection capability and reducing near-field blind zone.

[0112] Furthermore, when the first region reflects the emitted light, the transmittance of the first region is in the range of 2% to 10%; when the first region transmits the emitted light, the reflectance of the first region is in the range of 2% to 10%. Setting the transmittance or reflectance of the first region within a reasonable range can improve the echo signal strength of near-range targets while minimizing the impact on the emitted light intensity.

[0113] Furthermore, when the emitted light is reflected from the first region to the target object, the beam splitter includes an incident surface, a back surface, and multiple connecting surfaces. The incident surface and the back surface are arranged opposite to each other, and the connecting surfaces are located between the incident surface and the back surface. The emitted light is projected onto the incident surface. The connecting surface near the emitting module of the lidar faces away from the receiving device of the lidar. Because the connecting surface near the emitting module of the lidar faces away from the receiving device of the lidar, the reflected beam from the receiving module of the lidar is effectively reduced, thereby achieving the purpose of suppressing stray light and reducing interference with the echo light.

[0114] Furthermore, when the emitted light is reflected from the first region to the target object, the beam splitter includes an incident surface, a back surface, and multiple connecting surfaces. The incident surface and the back surface are arranged opposite to each other, and the connecting surfaces are located between the incident surface and the back surface. The emitted light is projected onto the incident surface. The connecting surfaces facing away from the emission module are parallel to the echo light to minimize the influence of the beam splitter on the echo light.

[0115] Furthermore, when the emitted light is reflected from the first region to the target, the lidar further includes a light-shielding plate located on the optical path through which the emitted light from the first region is transmitted. The light-shielding plate can absorb stray light, thereby reducing interference with the echo signal.

[0116] Furthermore, one end of the light-shielding plate is fixedly connected to the beam splitter, and the other end extends in a direction parallel to the echo light. Extending in a direction parallel to the echo light minimizes the impact of the light-shielding plate on the echo light, thus ensuring the echo signal strength and detection capability.

[0117] Furthermore, one end of the light-shielding plate is fixedly connected to the beam splitter, and the other end extends in a direction parallel to the echo light. The receiving module of the lidar includes a receiving lens, and the other end of the light-shielding plate extends to the receiving lens and contacts its surface. This contact between the other end of the light-shielding plate and the surface of the receiving lens provides additional mechanical support, ensuring stability and reducing interference from mechanical vibrations. Particularly in automotive lidar systems, this reduces the impact of vibration interference on the optical path and improves the stability of the lidar's detection capabilities.

[0118] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A light splitting device, which is suitable for a laser radar for coaxial transmission and reception, characterized in that, the laser radar transmits light to a target object, and the reflected light from the target object forms echo light; the light splitting device comprises: a first area corresponding to the position of the laser radar transmitting light; a second area surrounding the first area; the first area reflects the transmitting light to the target object, the second area transmits the echo light, and the first area partially transmits the echo light to the receiving module of the laser radar to eliminate the blind area of the laser radar; wherein the transmittance of the second area is not equal to the transmittance of the first area; the light splitting device further comprises an incident surface, a back surface and a plurality of connecting surfaces, the incident surface and the back surface are oppositely arranged, the connecting surface is located between the incident surface and the back surface, and the transmitting light is projected onto the incident surface; the connecting surface facing the transmitting module of the laser radar is away from the receiving device of the laser radar.

2. The light splitting device of claim 1, wherein The transmittance of the second area is greater than the transmittance of the first area.

3. The light splitting device according to any one of claims 1 to 2, wherein The transmittance of the first area is in the range of 2% to 10%.

4. The light splitting device of claim 1, wherein In the plane of the light beam incident surface of the light splitting device, the shape of the first area is the same as the spot shape of the transmitting light on the surface of the light splitting device.

5. The light splitting device of claim 4, wherein The laser radar comprises a VCSEL laser, and in the plane of the light beam incident surface of the light splitting device, the shape of the first area is an ellipse; or the laser radar comprises an EEL laser, and in the plane of the light beam incident surface of the light splitting device, the shape of the first area is a circle.

6. The light splitting device of claim 1, wherein The angle between the normal direction of the connecting surface facing the transmitting module and the direction vector of the echo light is greater than or equal to 90°.

7. The light splitting device of claim 6, wherein The optical axis of part of the transmitting light is orthogonal to the optical axis of part of the echo light, and the transmitting light is incident on the incident surface at an angle θ; The angle between the connecting surface facing the transmitting module and the negative direction of the normal of the incident surface is greater than or equal to θ.

8. The light splitting device of claim 1, wherein, When the first area reflects the transmitting 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 oppositely arranged, the connecting surface is located between the incident surface and the back surface, and the transmitting light is projected onto the incident surface; The connecting surface away from the transmitting module is parallel to the echo light.

9. The light splitting device of claim 1, wherein, When the first area reflects the transmitting light to the target object, the laser radar further comprises a light shield, which is located on the path of the transmitting light of the first area.

10. The light splitting device of claim 9, wherein, One end of the light shield is fixedly connected to the light splitting device, and the other end extends in a direction parallel to the echo light.

11. The light splitting device of claim 9, wherein, The receiving device of the laser radar comprises a receiving lens, and the other end of the light shield extends to the receiving lens and contacts the surface of the receiving lens.

12. The light splitting device of claim 11, wherein, The shape of the side of the light shield facing the receiving module of the laser radar is adapted to the surface shape of the receiving lens.

13. The light splitting device of claim 11, wherein, In the height direction, the size of the light shield is equal to the size of the receiving lens, and the height direction is orthogonal to both the transmitting light and the echo light.

14. A lidar, comprising: comprises: a transmitting device suitable for generating the transmitting light; a receiving device adapted to receive the echo light; a light splitting device according to any one of claims 1 to 13.

15. The lidar of claim 14, wherein, The emitted light and the echo light are coaxial after the light splitting device.

16. The lidar of claim 14, wherein, Further comprising: a rotating mirror, the emitted light after the light splitting device is reflected by the rotating mirror and exits to the three-dimensional space; The echo light is received by the receiving device after the light splitting device.

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