Optical scanner, laser detection system and autonomous vehicle

Abstract

The embodiment of the invention relates to an optical scanner. The optical scanner comprises a polarizing beam splitter, a wave plate and an optical phased array chip. Wherein the polarizing beam splitter is used for dividing incident light source light into first laser with a first polarization state and non-working light with a second polarization state, reflecting the first laser and transmitting the non-working light, and the first polarization state is different from the second polarization state. The wave plate is located on the reflection light-emitting side of the polarizing beam splitter and used for receiving the first laser and emitting second laser with a third polarization state different from the first polarization state and the second polarization state. And the optical phased array chip is used for receiving the second laser and emitting reference light, and the optical phased array chip is also used for changing the emitting angle of the reference light. The embodiment of the invention further relates to a laser detection system with the optical scanner and an automatic driving vehicle applying the laser detection system.

Description

Technical Field

[0001] This application relates to an optical scanner, a laser detection system having the optical scanner, and an autonomous vehicle using the laser detection system. Background Technology

[0002] Laser detection systems have broad application prospects in remote sensing and autonomous driving. One of the key aspects of achieving laser detection is the design of the optical scanner in the laser emitting device. The optical scanner is used to convert the light emitted from the laser source into reference light that is deflected to multiple angles for emission.

[0003] Existing optical scanners employ either micro-electro-mechanical system (MEMS) chips or directly combine mirrors with rotating motors for scanning. MEMS chips contain multiple rotatable micromirrors, whose deflection is controlled by a rocker arm to achieve multi-angle laser scanning. However, when the rocker arm or rotating motor vibrates, the internal leads of the optical scanner are at risk of breaking due to resonance, shortening its lifespan. Simultaneously, the generated reference light exhibits a divergence angle after passing through the micromirrors or mirrors, causing partial energy loss and resulting in an excessively short effective scanning distance for the reference light.

[0004] Existing optical scanners employ conventional beam splitters that split an incident beam between surface reflection and transmission to ensure that the incident light transmitted to the MEMS chip is on the same optical axis as its reflected light without deflection. However, since conventional beam splitters have a reflectivity and transmittance of 50% for unpolarized light, each pass through the beam splitter results in a 50% energy loss (50% transmission, 50% reflection). When the conventional beam splitter transmits light from the laser source to the MEMS chip, and then the reference light exits through the chip, the light experiences a total energy loss of 75% after passing through the beam splitter twice, ultimately reducing the luminous efficiency of the laser source. Furthermore, conventional beam splitters cannot block interference light from external light sources, which creates noise on the reference light and further affects the scanning quality of the optical scanner. To reduce the impact of low luminous efficiency on scanning quality, existing optical scanners require the addition of a focusing lens at the exit point of the reference light to concentrate the light energy, but this hinders the miniaturization of the optical scanner. Summary of the Invention

[0005] A first aspect of this application provides an optical scanner. The optical scanner includes:

[0006] A polarizing beam splitter is used to split incident light from a light source into a first laser beam with a first polarization state and a non-working beam with a second polarization state, and to reflect the first laser beam and transmit the non-working beam, wherein the first polarization state is different from the second polarization state.

[0007] A waveplate, located on the reflecting side of the polarizing beam splitter, is used to receive the first laser beam and emit a second laser beam with a third polarization state different from the first and second polarization states; and

[0008] An optical phased array chip is used to receive the second laser and emit a reference light. The optical phased array chip is also used to change the emission angle of the reference light.

[0009] The optical scanner provided in this application uses a polarizing beam splitter to select light with a specific polarization state and a waveplate to adjust its polarization state, converting the emitted light into a penetrable polarity, reducing light loss if the light passes through the polarizing beam splitter multiple times. Furthermore, the characteristics of the polarizing beam splitter are utilized to remove interference light from external light sources, improving scanning quality. An optical phased array chip replaces the existing MEMS chip, fully leveraging the all-solid-state structure and physical optical properties of the optical phased array chip to generate highly concentrated light energy that can be deflected at multiple angles, achieving high-efficiency light collection and a large field of view scanning effect, thus improving the scanning performance and lifespan of the optical scanner. Simultaneously, the elimination of the need for an additional light-collecting lens also facilitates the miniaturization of the optical scanner.

[0010] A second aspect of this application provides a laser detection system. The laser detection system includes:

[0011] A laser emitting device includes a laser source and an optical scanner as described in the first aspect above, wherein the laser source is used to emit light from the source, and the optical scanner is used to convert at least a portion of the light from the source into reference light for emission to a target; and

[0012] A laser receiving device is used to receive the detection light reflected by the target under test according to the reference light, and to obtain the distance information of the target under test according to the detection light.

[0013] The laser detection system provided in this application employs an optical scanner as described in the first aspect of the laser emitting device. This fully leverages the advantages of the optical scanner, such as low optical loss, high scanning quality, long service life, and miniaturization, thereby improving the overall system's detection performance. Based on this, the laser detection system more effectively emits high-quality reference light to the target, and the target obtains its distance information more accurately based on the detection light reflected from the reference light.

[0014] A third aspect of this application provides an autonomous driving vehicle. The autonomous driving vehicle includes:

[0015] The system includes a photography system and a laser detection system as described in the second aspect above, wherein the photography system is used to acquire image information of the target under test, and the laser detection system is used to acquire distance information of the target under test.

[0016] The autonomous vehicle provided in this application embodiment combines a photography system with the laser detection system described in the second aspect above, respectively, to acquire image information and distance information of the target. The autonomous vehicle fully utilizes the advantages of the laser detection system—high efficiency, long lifespan, and high performance—which helps improve the accuracy of the perception system in acquiring information about the target. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a laser detection system according to an embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the optical path for removing interference light in an optical scanner according to an embodiment of this application.

[0019] Figure 3 for Figure 1 The workflow diagram of the laser detection system.

[0020] Figure 4 for Figure 1 A schematic diagram of the reflective layer of the optical phased array chip.

[0021] Figure 5 Four sets Figure 1 A schematic diagram of the layout of the laser detection system.

[0022] Figure 6 This is a schematic diagram of the modules of an autonomous vehicle according to an embodiment of this application.

[0023] Explanation of key component symbols:

[0024] Laser Detection System 100

[0025] Laser emitting device 10

[0026] Laser source 11

[0027] Light Scanner 13

[0028] Polarizing beam splitter 131

[0029] Waveplate 133

[0030] Optical phased array chip 135

[0031] Collimation element 15

[0032] Drive circuit 17

[0033] Light source circuit 171

[0034] Scanning circuit 173

[0035] Laser receiver 30

[0036] Light sensor 31

[0037] Light receiving element 33

[0038] Amplifier circuit 35

[0039] Laser monitoring device 50

[0040] 200 autonomous vehicles

[0041] Sensing System 220

[0042] Camera System 221

[0043] Positioning System 240

[0044] Planning System 260

[0045] Control System 280

[0046] Reflective layer R

[0047] Micro-reflection unit R1

[0048] Light source L1

[0049] First laser L2

[0050] Second laser L3

[0051] Reference light L4

[0052] L5 Probe

[0053] Interference light L6

[0054] Non-working light LF

[0055] First Optical Path LP1

[0056] Second optical path LP2

[0057] Target Q

[0058] Scanning angle E

[0059] Light collection angle F

[0060] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0061] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0062] This application provides a laser detection system. Please refer to the following: Figure 1 and Figure 3 The laser detection system 100 includes a laser emitting device 10 and a laser receiving device 30. The laser emitting device 10 includes a laser source 11 and an optical scanner 13. The laser source 11 emits light source light L1, and the optical scanner 13 converts the light source light L1 into reference light L4, which is then emitted to the target Q. The laser receiving device 30 receives the detection light L5 reflected by the target Q according to the reference light L4, and obtains the distance information of the target Q based on the detection light L5.

[0063] In this embodiment, the laser source 11 includes a light-emitting array composed of at least one laser, such as a light-emitting array composed of semiconductor lasers or distributed feedback lasers that meet range performance requirements. Accordingly, the light source L1 includes at least the light emitted by at least one laser in the light-emitting array. Figure 1 For clarity, only the optical path transformation of a single beam of light emitted by a laser is shown in the diagram. More specifically, the light source L1 emitted by laser source 11 satisfies a wavelength range of 905 nm to 1550 nm.

[0064] In this embodiment, the laser emitting device 10 further includes a collimating element 15 located between the laser source 11 and the optical scanner 13. The collimating element 15 is located in the optical path of the light source L1 and is used to collimate the light source L1.

[0065] In this embodiment, the optical scanner 13 includes a polarizing beam splitter 131, a waveplate 133, and an optical phased array chip 135.

[0066] The polarizing beam splitter 131 is located on the light-emitting side of the collimating element 15, that is, on the optical path of the light source L1. The polarizing beam splitter 131 is used to separate the collimated light source L1 into a first laser L2 with a first polarization state and a non-working light LF with a second polarization state, and to reflect the first laser L2 and transmit the non-working light LF. The first polarization state is different from the second polarization state.

[0067] More specifically, the light source L1 includes a first laser L2. When the polarizing beam splitter 131 is located in the optical path of the light source L1, it is equivalent to being located in the optical path of the first laser L2. The polarizing beam splitter 131 is used to guide at least a portion of the first laser L2 to the waveplate 133 by reflection. Specifically, the polarizing beam splitter 131 is a polarizing beam splitter (PBS), which is used to split the incident light into S-polarized light and P-polarized light, and to reflect the S-polarized light while transmitting the P-polarized light.

[0068] The PBS is an optical element constructed by depositing multiple layers of film on the inclined surfaces of two right-angle prisms and bonding them together into a cubic structure. Utilizing the property that the transmittance of P-polarized light is 1 while the transmittance of S-polarized light is less than 1 when incident light is at Brewster's angle, it achieves complete transmission of P-polarized light and reflection of the vast majority (at least 90%) of S-polarized light after the incident light passes through each layer of the film structure multiple times at Brewster's angle. In this embodiment, the first laser L2 consists only of S-polarized light reflected by the polarizing beam splitter 131, and the non-working light LF consists only of P-polarized light transmitted by the polarizing beam splitter 131. In other embodiments, the first laser L2 consists only of P-polarized light transmitted by the polarizing beam splitter 131, and the non-working light LF consists only of S-polarized light reflected by the polarizing beam splitter 131.

[0069] In addition, please see Figure 2 The polarizing beam splitter 131 is also used to remove interference light L6 from the external light source in the laser emitting device 10, causing the S-polarized light in the interference light L6 to be removed along the first optical path LP1, and simultaneously causing the P-polarized light in the interference light L6 to be removed along the second optical path LP2. In other words, the interference light L6 incident on the optical scanner 13 will no longer be emitted along the emission direction of the reference light L4 and form noise, thus improving the scanning quality of the optical scanner 13.

[0070] Please continue reading. Figure 1 Waveplate 133 is located on the reflected light output side of polarizing beam splitter 131, specifically on the optical path of the first laser L2 reflected by polarizing beam splitter 131. Waveplate 133 receives the first laser L2 from polarizing beam splitter 131 and outputs a second laser L3 with a third polarization state, which is different from both the first and second polarization states. Specifically, waveplate 133 is a quarter-wave plate. When the first laser L2 is S-polarized light, the non-working light LF is P-polarized light, and the second laser L3 output after the quarter-wave plate receives the first laser L2 is circularly polarized light.

[0071] The optical phased array chip 135 is located on the side of the waveplate 133 away from the polarizing beam splitter 131, specifically in the optical path of the second laser L3 emitted from the waveplate 133. The optical phased array chip 135 receives the second laser L3 from the waveplate 133 and emits a reference light L4 to the target Q. The optical phased array chip 135 also changes the emission angle of the reference light L4. When emitted, the reference light L4 passes sequentially through the waveplate 133 and the polarizing beam splitter 131 before reaching the target Q. Specifically, the reference light L4 is converted to a P-polarized state by the waveplate 133, and after passing through the polarizing beam splitter 131, it is completely transmitted as P-polarized light and emitted in a direction different from the non-working light LF and the second laser L3, effectively reducing the overall optical loss of the light source light L1 in the optical scanner 13.

[0072] Specifically, the optical phased array chip 135 includes a reflective layer R located near the waveplate 133, and the second laser L3 is converted into reference light L4 by the reflective layer R. For more details, please refer to [reference needed]. Figure 1 and Figure 4 The surface of the reflective layer R has multiple micro-reflective units R1 arranged on it. It should be noted that this application does not limit the specific structure and arrangement of the micro-reflective units R1. In this embodiment, the micro-reflective units R1 are grating structures, and the reference light L4 is formed by the collection of light emitted from all the micro-reflective units R1. When the second laser L3 is guided to the reflective layer R, the second laser L3 is refracted and reflected at the micro-reflective units R1 to form the reference light L4. The collection of light emitted from all the micro-reflective units R1 forms the reference light L4 emitted in a certain direction. However, because the directions of the light collection emitted from the micro-reflective units R1 are different, the reference light L4 can be emitted in multiple directions. For ease of understanding, Figure 1 The incident second laser L3 and the outgoing reference light L4 are simply shown with arrows. At the same time, the wave plate 133 and the polarizing beam splitter 131 are also located in the optical path of the reference light L4. After being emitted, the reference light L4 passes through the wave plate 133 and the polarizing beam splitter 131 in sequence and is then guided to the target Q to be measured.

[0073] In this embodiment, please refer to Figure 3 The laser emitting device 10 also includes a driving circuit 17. The driving circuit 17 includes a light source circuit 171 and a scanning circuit 173. The light source circuit 171 is used to power the laser source 11 to emit light source light L1, and the scanning circuit 173 is used to drive the optical phased array chip 135 to deflect the emission angle of the reference light L4.

[0074] Specifically, the scanning circuit 173 outputs control voltages of different values ​​to change the physical and optical properties of the reflective layer R, thereby changing the light emission direction at the micro-reflective unit R1. For example, when the reflective layer R is a reflective liquid crystal layer, it contains multiple liquid crystal molecules arranged in an orderly manner. The control voltage can be used to control the deflection of the liquid crystal molecules, thereby changing the refractive index of the reflective layer R. When the second laser L3 is refracted and simultaneously reflected at all micro-reflective units R1 to form reference light L4, the emission direction of the reference light L4 is affected by the refractive index of the reflective layer R, that is, it changes accordingly.

[0075] In this embodiment, the laser receiving device 30 includes a photosensor 31 and a light-receiving element 33. The photosensor 31 is used to acquire distance information of the target Q based on the probe light L5, and the light-receiving element 33 is used to converge and guide the probe light L5 to the photosensor 31, and the light-receiving element 33 is configured to surround the photosensor 31. Specifically, the light-receiving element 33 can be selected from lenses that meet the light-receiving effect, such as aspherical lenses, Fresnel lenses, or freeform lenses.

[0076] In this embodiment, the light-collecting element 33 is made of a material with a high refractive index, for example, the refractive index of the material is selected to be above 1.8, so that the light-collecting element 33 has a better light-collecting effect on the probe light L5, and it is also beneficial to make the light-collecting element 33 thinner and lighter.

[0077] The laser receiving device 30 also includes an amplification circuit 35, which amplifies the amplitude of the output signal of the photosensor 31 and adjusts the output signal with higher precision, thereby improving the working accuracy of the photosensor 31.

[0078] Please see Figure 1 The laser detection system 100 also includes a laser monitoring device 50, which is located on the optical path of the non-working light LF. In this embodiment, the laser monitoring device 50 is located between the laser emitting device 10 and the laser receiving device 30 to monitor and receive the non-working light LF in real time, effectively blocking the transmission of the non-working light LF to the laser receiving device 30, thus preventing interference to the photosensor 31. When the laser monitoring device 50 receives the non-working light LF, it also converts the returned non-working light LF into an electrical signal and monitors the frequency, power, and waveform of the electrical signal of the non-working light LF in real time. For example, it monitors the frequency range of 200–1000 kHz, the power range of 50–100 watts (W), and the waveform type as square wave or sine wave. At the same time, the laser monitoring device 50 feeds back the collected information to the laser source 11 of the laser emitting device 10 and the photosensor 31 of the laser receiving device 30 in real time, so that the laser source 11 and the photosensor 31 can adjust their working states accordingly.

[0079] The laser monitoring device 50 includes a monitoring photodiode (MPD), such as an avalanche photodiode (APD) or a single photon avalanche diode (SPAD).

[0080] The laser emitting device 10 and the laser receiving device 30 are arranged at intervals or closely together, so that the laser detection system 100 can use techniques such as time of flight (TOF) ranging, amplitude modulated continuous wave (AMCW) ranging, and frequency modulated continuous wave (FMCW) ranging to calculate and obtain the distance information of the target Q by comparing the reference light L4 and the probe light L5.

[0081] In this embodiment, the scanning angle E of the reference light L4 emitted by the laser emitting device 10 includes a horizontal angle range of 30° to 60° and a vertical angle range of 20° to 30°. Simultaneously, the light receiving angle F of the laser receiving device 30 has the same angle range as the scanning angle E of the single laser emitting device 10. Therefore, the laser detection system 100 can detect the distance information of the target Q within a field of view of at least 30° to 60° horizontally and 20° to 30° vertically. Furthermore, the laser detection system 100 can also detect the distance information of the target Q within a distance range of 100 meters to 200 meters.

[0082] Furthermore, multiple laser detection systems 100 can be combined and used together, and the overall system is not limited to a single set of laser emitting devices 10 and laser receiving devices 30. When the combined system of multiple laser detection systems 100 includes multiple sets of laser emitting devices 10 and laser receiving devices 30, the laser detection systems 100 can be arranged in a 1×2, 1×3, 1×4, or similar manner in the horizontal and / or vertical directions, increasing the overall scanning angle E and light-receiving angle F, thereby achieving the detection of the target Q within a wider field of view. Specifically, a 1×4 arrangement means setting up one row horizontally and four columns vertically. For example, please refer to [link to example]. Figure 5 The figure shows a combination of four laser detection systems 100 arranged in a 1×4 arc in the horizontal direction, which can detect the distance information of the target Q in the horizontal direction within an angle range of 120° to 240°.

[0083] In addition, in order to improve the light efficiency, the surfaces of the optical elements through which the light passes in the laser detection system 100 are coated with anti-reflection films that are suitable for the wavelength range of the light source L1, such as collimating element 15, polarizing beam splitter 131, waveplate 133 and light receiving element 33.

[0084] The laser detection system 100 provided in this application embodiment uses a polarizing beam splitter 131 and a waveplate 133 in the optical scanner 13 to convert the emitted reference light L4 into a penetrable polarity, reducing light loss. Furthermore, utilizing the characteristics of the polarizing beam splitter 131, interference light L6 from external light sources in the emission direction of the reference light L4 is removed, improving scanning quality. An optical phased array chip 135 replaces the existing MEMS chip, fully leveraging the all-solid-state structure and physical optical properties of the optical phased array chip 135 to generate a reference light L4 with highly concentrated light energy that can be deflected at multiple angles, achieving high-efficiency light collection and a large field of view scanning effect, thus improving the scanning performance and lifespan of the optical scanner 13. Simultaneously, the elimination of the need for an additional light-collecting lens also facilitates the miniaturization of the laser detection system 100.

[0085] This application also provides an autonomous driving vehicle. Please refer to... Figure 6 The autonomous vehicle 200 includes a perception system 220, a positioning system 240, a planning system 260, and a control system 280. The perception system 220 includes a photography system 221 and a laser detection system 100. The photography system 221 acquires image information of a target Q, and the laser detection system 100 acquires distance information of the target Q. The positioning system 240 obtains the location information of the autonomous vehicle 200 by connecting to a satellite navigation system. The planning system 260 plans the driving route of the autonomous vehicle 200 based on the information provided by the perception system 220 and the positioning system 240. The control system 280 adjusts the speed and steering angle of the autonomous vehicle 200 in real time based on the driving route provided by the planning system 260.

[0086] In this embodiment, the photography system 221 includes at least a plurality of cameras or other sensors that meet the functional requirements and can work in conjunction with the laser detection system 100. When the target Q is identified in the working state, the image information and distance information of the target Q can be acquired synchronously or sequentially. The image information and the distance information can be combined with each other.

[0087] The autonomous vehicle 200 provided in this application embodiment combines a photography system 221 and a laser detection system 100 in the perception system 220 to acquire image information and distance information of the target Q to be measured, respectively. The autonomous vehicle 200 of this application fully utilizes the advantages of the laser detection system 100, such as high efficiency, long lifespan, and high performance, which helps improve the accuracy of the perception system 220 in acquiring information about the target Q. It also enables the planning system 260 to more accurately plan the driving route of the autonomous vehicle 200 based on the information provided by the perception system 220 and the positioning system 240, so that the control system 280 can adjust the speed and steering angle of the autonomous vehicle 200 in real time to avoid or reach the target Q.

[0088] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. An optical scanner, characterized in that, include: A polarizing beam splitter is used to split incident light from a light source into a first laser beam with a first polarization state and a non-working beam with a second polarization state, and to reflect the first laser beam and transmit the non-working beam, wherein the first polarization state is different from the second polarization state. A waveplate, located on the reflecting side of the polarizing beam splitter, is used to receive the first laser and emit a second laser with a third polarization state different from the first and second polarization states. as well as An optical phased array chip is used to receive the second laser and emit a reference light. The optical phased array chip is also used to change the emission angle of the reference light.

2. The optical scanner as described in claim 1, characterized in that, The optical phased array chip includes a reflective layer, and the second laser is converted into reference light by the reflective layer. The reference light is emitted after passing through the waveplate and the polarizing beam splitter.

3. The optical scanner as described in claim 2, characterized in that, The reference light is converted to the second polarization state by the waveplate, and after passing through the polarizing beam splitter, it is transmitted and emitted in a direction different from the non-working light and the second laser.

4. The optical scanner as described in any one of claims 1-3, characterized in that, The first polarization state is an S-polarization state, the second polarization state is a P-polarization state; the waveplate includes a quarter-waveplate, and the third polarization state is a circular polarization state.

5. A laser detection system, characterized in that, include: A laser emitting device includes a laser source and an optical scanner as described in any one of claims 1-4, wherein the laser source is used to emit light from the light source, and the optical scanner is used to convert at least a portion of the light from the light source into reference light for emission to a target under test; as well as A laser receiving device is used to receive the detection light reflected by the target under test according to the reference light, and to obtain the distance information of the target under test according to the detection light.

6. The laser detection system as described in claim 5, characterized in that, The laser source is a semiconductor laser or a distributed feedback laser.

7. The laser detection system as described in claim 5, characterized in that, The light source includes wavelengths from 905 nanometers to 1550 nanometers.

8. The laser detection system as described in claim 5, characterized in that, The laser emitting device further includes a light source circuit and a scanning circuit. The light source circuit is used to drive the laser source to emit the light source light, and the scanning circuit is used to drive the optical phased array chip to deflect the emission angle of the reference light.

9. The laser detection system as described in claim 5, characterized in that, The laser receiving device includes a light sensor and a light receiving element. The light sensor is used to acquire the position information of the target under test based on the probe light. The light receiving element is used to converge and guide the probe light to the light sensor.

10. An autonomous vehicle, characterized in that, include: The imaging system and the laser detection system as described in any one of claims 5-9, wherein the imaging system is used to acquire image information of the target under test, and the laser detection system is used to acquire distance information of the target under test.

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