TWI846002B - Laser detection system and vehicle - Google Patents

Abstract

The present disclosure provides a laser detection system including a light source module, an optical isolator, a scanner, and a detector. The light source module is used to emit first laser having a first polarization direction. The optical isolator is on an optical path of the first laser and is used to emit second laser according to the first laser from the light source module and prevent the second laser transmitting towards the light source module. The scanner is on an optical path of the second laser for reflecting the second laser to project reference light a target to be measured. The detector is used to receive detection light reflected by the target according to the reference light and generate position information of the target according to the detection light. The present disclosure also provides a vehicle.

Description

Laser detection system and vehicle

This application relates to the field of laser detection technology, and in particular to a laser detection system and a vehicle using the laser detection system.

A traditional laser detection system includes a light source, a spectroscope and a detector. The light source is used to emit detection light to the spectroscope. It is difficult for all the detection light incident on the spectroscope to be guided to the detection object, and a small part of the detection light is scattered multiple times in the laser detection system. Part of the detection light that is scattered multiple times in the laser detection system may return to the light source and interfere with the light source; it may also be incident on the detector and affect the detection result of the detector.

The first aspect of the present application provides a laser detection system, comprising: a light source module, used to emit a first laser, the first laser having a first polarization direction; an optical isolator, located on the optical path of the first laser, used to transmit the first laser from the light source module to emit a second laser, and also used to block the second laser from being transmitted toward the light source module; a scanner, located on the optical path of the second laser, used to reflect the second laser to project a reference light to a target to be detected; and a detector, used to receive a detection light reflected by the target to be detected based on the reference light, and used to obtain the position information of the target to be detected based on the detection light.

The second aspect of the present application provides a vehicle, comprising: a vehicle body; a laser detection system as described above, the laser detection system being fixed to the vehicle body and used to detect whether there is a target to be detected on the path of the vehicle body, and when there is a target to be detected, obtaining the distance information of the target to be detected.

The above laser detection system, by setting up an optical isolator, allows the first laser to be transmitted through the optical isolator, and thus be applied to the subsequent laser detection process; it also prevents the stray light generated in the subsequent optical path from passing through the optical isolator, which can avoid the problem of stray light incident on the light source module to generate light interference, thereby helping to improve the accuracy of the position information of the target to be detected.

1: Vehicles

10: Vehicle body

11: Control system

20: Laser detection system

21: Light source module

211: Laser source

212: Wave plate assembly

213: Half wave plate

214: Quarter wave plate

215: Light blocking element

216: Light hole

217: Collimation element

22: Optical isolator

221: Polarizer

222: Faraday rotator

223: Polarizer

23: Scanner

24: Detector

25: Beam splitter

251: First light incident surface

252: Second light-entering surface

253: Spectral surface

26: Filter

27: Focusing lens

2: Target to be tested

L1: Light source

L2: First Laser

L3: Second laser

L4: Reference light

L5: Detection light

Figure 1 is a schematic diagram of the structure of the vehicle and the target to be measured in the embodiment of this application.

Figure 2 is a schematic diagram of the structure of the laser detection system in Figure 1.

Figure 3 is a schematic diagram of the structure of the wave plate assembly in Figure 2.

Figure 4 is a schematic diagram of the structure of the light-blocking element in Figure 2.

Figure 5 is a schematic diagram of the structure of the optical isolator in Figure 2.

Please refer to Figure 1. The vehicle 1 provided in this application includes a vehicle body 10 and a laser detection system 20 fixed on the vehicle body 10.

Obstacles (hereinafter referred to as the target to be detected 2) may appear in the direction of travel of the vehicle 1 (or the vehicle body 10). If the vehicle 1 hits the target to be detected 2, it will hinder the driving or even damage the vehicle. During the movement of the vehicle body 10, the laser detection system 20 is used to continuously detect whether there is a target to be detected 2 on the path of the vehicle body 10. When the presence of the target to be detected 2 is detected, the laser detection system 20 is also used to obtain the position information of the target to be detected 2. In this embodiment, the distance information includes the distance between the target to be detected 2 and the vehicle body 10 and the orientation of the target to be detected 2 relative to the vehicle body. The vehicle body 10 also includes a control system 11, and the control system 11 can communicate with the laser detection system 20. When the laser detection system 20 obtains the position information of the target 2 to be detected, the control system 11 can remind the driver to pay attention to the target 2 to be detected in a preset manner (such as image or voice). Therefore, the laser detection system 20 in this application can be used to remind the driver of the road conditions while the vehicle 1 is moving, thereby helping to avoid damage to the vehicle body 10.

In another embodiment of the present application, the vehicle 1 is an unmanned vehicle. In this embodiment, the control system 11 is used to control the automatic driving vehicle body 10 according to the position information of the target 2 to be detected obtained by the laser detection system 20, so as to drive along a preset path and avoid the target 2 to be detected on the driving path.

Please refer to Figure 2. The laser detection system 20 of this embodiment includes a light source module 21, an optical isolator 22, a scanner 23 and a detector 24.

In this embodiment, the light source module 21 includes a laser source 211 and a wave plate assembly 212.

The laser source 211 is used to emit the light source L1. In this embodiment, the laser source 211 includes at least one laser diode for emitting infrared laser. In other embodiments, the laser source 211 may also include at least one laser. In this embodiment, part of the light source L1 has a first polarization direction, and part has a second polarization direction. That is, part of the light source L1 is P polarized light, and part of the light source L1 is S polarized light.

The wave plate assembly 212 is located on the optical path of the light source L1. The wave plate assembly 212 is used to receive the light source L1 and to convert the polarization direction of the light source L1. That is, when the light source L1 with the first polarization direction is incident on the wave plate assembly 212, it will be converted by the wave plate assembly 212 to have the second polarization direction; when the light source L1 with the second polarization direction is incident on the wave plate assembly 212, it will be converted by the wave plate assembly 212 to have the first polarization direction. In other words, the wave plate assembly 212 is used to convert P polarized light into S polarized light, and to convert S polarized light into P polarized light.

In this embodiment, due to the structural characteristics of the laser source 211 itself, the amount of S polarized light in the emitted light source light L1 is much greater than the amount of P polarized light (98% S polarized light and 2% P polarized light), but the subsequent optical path mainly uses P polarized light. Therefore, in this embodiment, the polarization direction of the light source light L1 is converted by setting a wave plate assembly 212 so that the light passing through the wave plate assembly 212 is almost all P polarized light, which can be used in the subsequent optical path. Therefore, the wave plate assembly 212 is conducive to improving the light utilization rate.

In this embodiment, the wave plate assembly 212 includes a half wave plate 213. In other embodiments, the wave plate assembly 212 may also include two quarter wave plates 214 arranged in sequence (see FIG. 3).

In this embodiment, the light source module 21 also includes a light blocking element 215. The light blocking element 215 is located between the laser source 211 and the wave plate assembly 212. Please refer to Figure 4. In this embodiment, the light blocking element 215 includes a light shielding material, which is flat as a whole, and has a light hole 216 near the central area (geometric center, such as the center of a circle, the intersection of the diagonals of a square). The light hole 216 on the light blocking element 215 is set corresponding to the laser source 211, so that the light source light L1 can be transmitted through the light hole 216.

In this embodiment, after the light source light L1 is emitted from the light source module 21, a part of it is used by the subsequent optical path to realize laser detection, and the other part is difficult to be used for laser detection and will be lost when propagating between the optical elements of the laser detection system 20. This part is hereinafter referred to as stray light. During the propagation process, the stray light may be incident on the laser source 211 and generate light interference.

Therefore, in this embodiment, the light hole 216 on the light blocking element 215 is a circular hole, and its size is set according to the size of the laser source 211. That is, the size of the light hole 216 is slightly larger than the size of the laser source 211. In this way, the light source light L1 emitted by the laser source 211 can pass through the light hole 216 as much as possible. In addition, since the light blocking element 215 includes a light shielding material, the stray light incident on the light source module 21 will be blocked by the light blocking element 215. If the stray light wants to reach the laser source 211, it must pass through the light hole 216. However, the propagation path of the stray light is relatively chaotic, and the probability of passing through the light hole 216 is extremely small. Therefore, in this embodiment, the light-blocking element 215 can prevent stray light from entering the laser source 211 and causing light interference to a certain extent.

Please refer to Figure 2 again. In this embodiment, the light source module 21 also includes a collimating element 217. The collimating element 217 is located between the laser source 211 and the light blocking element 215 and on the optical path of the light source light L1. It is used to collimate the light source light L1 from the laser source 211 to reduce the divergence angle of the laser source 211 so that the light source light L1 can pass through the light hole 216 smoothly. If the light source light L1 cannot pass through the light hole 216, it will be lost. Therefore, the collimating element 217 is conducive to improving the utilization rate of the light source light L1.

Please refer to FIG. 5. In this embodiment, the light emitted from the wave plate assembly 212 is defined as the first laser L2. The optical isolator 22 is located on the optical path of the first laser L2, and is used to receive the first laser L2 and emit the second laser L3 according to the first laser L2. The polarization direction of the second laser L3 is rotated 45° relative to the first laser L2.

In this embodiment, the optical isolator 22 includes a polarizer 221, a Faraday rotator 222, and an analyzer 223. The polarizer 221, the Faraday rotator 222, and the analyzer 223 are sequentially located on the optical path of the first laser L2. After passing through the polarizer 221, the first laser L2 is converted into linearly polarized light. When passing through the Faraday rotator 222, the polarization direction of the first laser L2 is rotated by 45°. The analyzer 223 is 45° with the polarizer 221, and the first laser L2 with the polarization direction rotated can just pass through the analyzer 223. The light passing through the analyzer 223 is defined as the second laser L3 mentioned above.

The second laser L3 emitted from the analyzer 223 may be partially lost when propagating in the subsequent optical path. The lost part may return to the optical isolator 22 as stray light. When the stray light propagates toward the optical isolator 22, it passes through the analyzer 223, the Faraday rotator 222 and the polarizer 221 in sequence. At this time, only the stray light parallel to the direction of the analyzer 223 can pass through the analyzer 223 and enter the Faraday rotator 222. When the stray light enters the Faraday rotator 222, its polarization direction will be deflected by 45°. As mentioned above, the analyzer 223 itself has a 45° angle with the polarizer 221, and the stray light is deflected by 45°, so the stray light emitted from the Faraday rotator 222 has a 90° angle with the polarizer 221, that is, the stray light emitted from the Faraday rotator 222 is perpendicular to the direction of the polarizer 221, and will be blocked by the polarizer 221 and will not continue to propagate toward the light source module 21. Therefore, in this embodiment, by setting the optical isolator 22, stray light can also be prevented from being incident on the light source module 21 to cause light interference.

Please refer to Figure 2 again. The scanner 23 is located on the optical path of the second laser L3 and is used to reflect the received second laser L3. In this embodiment, the scanner 23 is also used to circumvent the received second laser L3 to generate reference light L4, which is structured light. The scanner 23 in this embodiment is an electrically driven scanner. That is, by changing the voltage value applied to the scanner 23, the rotation angle of the scanner 23 can be changed. By changing the rotation angle of the scanner 23, the phase of the light reflected by the scanner 23 can be modulated, thereby modulating the light to interfere and generate the corresponding structured light (i.e., reference light L4).

As mentioned above, the laser detection system 20 of the present application is applied to the vehicle 1, that is, the laser detection system 20 of the present application is a vehicle-mounted laser detection system. The vehicle is frequently bumped and vibrated during driving, which requires a higher vibration resistance of the scanner 23. The known mechanically driven scanner 23 is prone to deflection errors due to jitter, while the electrically driven scanner 23 used in the present application is conducive to improving the working stability of the scanner 23.

In this embodiment, the laser detection system 20 further includes a beam splitter 25. The beam splitter 25 is located on the optical path of the second laser L3, and is used to guide the second laser L3 to the scanner 23. The beam splitter 25 is also located on the optical path of the reference light L4, and is used to guide the reference light L4 to the target 2 to be measured. The beam splitter 25 has a first light incident surface 251, a second light incident surface 252, and a splitting surface 253. In this embodiment, the second laser L3 is vertically incident from the first light incident surface 251, and the reference light L4 is vertically incident from the second light incident surface 252. In addition, in this embodiment, when the second laser L3 is incident on the splitting surface 253, part of it is reflected to the scanner 23, and the other part is transmitted from the splitting surface 253 along the original optical path. When the reference light L4 is incident on the splitter surface 253, part of it is reflected, and the other part is transmitted from the splitter surface 253 along the original light path.

Furthermore, the scanner 23 is also used to guide the reference light L4 to the target 2 to be measured through the beam splitter 25. When the reference light L4 irradiates the target 2 to be measured, it will be reflected by the target 2 to be measured. In this embodiment, the light reflected by the target 2 to be measured is defined as the detection light L5.

In this embodiment, the detector 24 is located on the optical path of the detection light L5, and is used to receive the detection light L5 and obtain the position information of the target 2 to be detected according to the detection light L5. In this embodiment, the detector 24 includes a plurality of photoelectric elements (not shown), each of which is used to perform photoelectric conversion when receiving the detection light L5 to generate a sensing electrical signal corresponding to the detection light L5, and the sensing electrical signal can be used to calculate the position information of the target 2 to be detected.

In this embodiment, the laser detection system 20 also includes a filter 26. The filter 26 is located on the optical path of the detection light L5 and is used to filter out ambient light. As mentioned above, the detector 24 is used to obtain the position information of the target 2 to be detected based on the received detection light L5. The light incident on the detector 24 together with the detection light L5 may also include ambient light (light in the environment where the laser detection system 20 is located). However, when the detector 24 also receives ambient light, the position information of the target 2 to be detected obtained by it may produce errors. Therefore, in this embodiment, filtering the ambient light by the filter is beneficial to improve the accuracy of the position information obtained by the detector 24.

In this embodiment, the laser detection system 20 also includes a focusing lens 27. The focusing lens 27 is located on the optical path of the detection light L5 and between the filter 26 and the detector 24. Since the detection light L5 reflected by the target 2 has a large divergence angle, it is difficult for all of it to be received by the detector 24. In this embodiment, by setting the focusing lens 27 to focus the detection light L5 to the detector 24, it is beneficial to improve the light utilization rate of the detection light L5, and thus to improve the accuracy of the position information.

In the laser detection system 20 of the present application, the beam splitter 25 is used to reflect part of the second laser L3 and transmit part of the reference light L4, and is also used to transmit another part of the second laser L3 and reflect another part of the reference light L4. The transmitted other part of the second laser L3 and the reflected other part of the reference light L4 are difficult to be used as laser detection by the subsequent optical path, and will be lost. The above-mentioned lost light is propagated in the laser detection system 20 as stray light, and part of the stray light will even propagate toward the light source module 21, resulting in light interference.

In this embodiment, by providing the optical isolator 22, the first laser L2 can be transmitted through the optical isolator 22, and thus be applied to the subsequent laser detection process. It also prevents stray light from passing through the optical isolator, which can prevent stray light from entering the light source module 21 and generating light interference.

Furthermore, in this embodiment, by providing the light-blocking element 215, the stray light can be prevented from further incident on the laser source 211 from a physical structure perspective.

In summary, the laser detection system 20 of the present application and the vehicle 1 using the laser detection system 20 can effectively prevent stray light from entering the light source module 21 to generate light interference, thereby helping to improve the accuracy of the position information of the target 2 to be detected.

Ordinary technical personnel in this technical field should recognize that the above implementation methods are only used to illustrate the present invention, and are not used as limitations on the present invention. As long as they are within the spirit of the present invention, appropriate changes and modifications to the above implementation examples are within the scope of protection required by the present invention.

20: Laser detection system

21: Light source module

211: Laser source

212: Wave plate assembly

213: Half wave plate

215: Light blocking element

216: Light hole

217: Collimation element

22: Optical isolator

23: Scanner

24: Detector

25: Beam splitter

251: First light incident surface

252: Second light-entering surface

253: Spectral surface

26: Filter

27: Focusing lens

2: Target to be tested

L1: Light source

L2: First Laser

L3: Second laser

L4: Reference light

L5: Detection light

Claims (9)

A laser detection system, which is improved in that it includes: a light source module, used to emit a first laser, the first laser having a first polarization direction; an optical isolator, located in the optical path of the first laser, used to transmit the first laser from the light source module to emit a second laser, and also used to block the second laser from being transmitted toward the light source module, the second laser having a second polarization direction different from the first polarization direction; a scanner, located in the optical path of the second laser, used to reflect the second laser to project a reference light to a target to be detected, the scanner is an electrically driven scanner, and the reference light is a structure light; and a detector for receiving the detection light reflected by the target to be measured according to the reference light, and for obtaining the position information of the target to be measured according to the detection light, the detector comprising a plurality of photoelectric elements, each of which is used to perform photoelectric conversion when receiving the detection light to generate an induction electrical signal, and the induction electrical signal is used to calculate the position information; wherein the voltage value of the scanner is used to change the rotation angle of the scanner, the rotation angle is used to modulate the phase of the light reflected by the scanner, and the phase is used to modulate the interference of the light reflected by the scanner to generate the structured light. The laser detection system as described in claim 1, wherein the light source module comprises: a laser source for emitting light source light; and a wave plate assembly located in the optical path of the light source light, for converting at least part of the light source light into a first laser having the first polarization direction. A laser detection system as described in claim 2, wherein the wave plate assembly includes a half wave plate or two quarter wave plates. The laser detection system as described in claim 2, wherein the light source module further includes a light-shielding element, and the light-shielding element is located between the laser source and the wave plate assembly; the light-shielding element includes a light-shielding material, and the light-shielding element is provided with a light-through hole, and the light from the light source is incident on the wave plate assembly from the light-through hole. A laser detection system as described in claim 1 or 2, wherein the first laser is P-polarized light. The laser detection system as described in claim 1, further comprising a beam splitter, the beam splitter being located in the optical path of the second laser and used to guide part of the second laser to the scanner; the beam splitter is also used to guide part of the reference light to the target to be detected. A laser detection system as described in claim 6, wherein the scanner is also used to diffract the received second laser. The laser detection system as described in claim 1 further includes a filter, which is located in the optical path of the detection light and is used to filter out ambient light. A vehicle, the improvement of which comprises: a vehicle body; a laser detection system as described in any one of claims 1 to 8, wherein the laser detection system is fixed to the vehicle body and is used to detect whether there is a target to be detected on the path of the vehicle body, and when there is a target to be detected, obtain the distance information of the target to be detected.

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