Laser emission device, lidar including same, and detection method

Abstract

The present invention provides a laser emission device, comprising: a transmitting unit configured to sequentially emit continuous lasers of a plurality of different wavelengths; a beam splitting unit disposed downstream of the optical path of the transmitting unit and configured to deflect the continuous lasers of the plurality of different wavelengths at different angles according to their wavelengths; and a scanning unit disposed downstream of the optical path of the beam splitting unit and configured to receive the deflected continuous lasers and scan them out into a target space to cover a plurality of field of view regions corresponding to the plurality of wavelengths.

Description

Technical Field

[0001] The present invention generally relates to the technical field of laser detection, and particularly relates to a laser emitting device, a lidar including the same, and a method for detecting using the lidar. Background Art

[0002] Frequency Modulation Continuous Wave (FMCW) radar refers to a continuous wave radar whose transmitted frequency is modulated by a specific signal. The FMCW radar emits a continuous wave with a changing frequency within a sweep period. The echo reflected by the target object has a certain frequency difference from the transmitted signal, and the radial velocity and distance of the target can be obtained after processing the measured frequency difference between the two. The frequency of the beat frequency signal is relatively low, generally in kHz, so the hardware processing is relatively simple, suitable for data acquisition and digital signal processing; moreover, the required peak value of the continuous wave transmission power is low and it is easy to modulate, all of which make the FMCW radar a commonly used radar solution.

[0003] The current FMCW radar adopts a single light source continuous wave laser combined with a galvanometer scanning scheme, and the horizontal field of view (FOV) is usually about 40°. However, for a forward radar used in autonomous driving, the horizontal field of view usually needs to be about 120°. The hybrid solid-state radar using laser pulse ranging generally uses multiple light sources with different emission directions to achieve field of view stitching. However, the basic principle of the FMCW radar is coherent detection, which requires extremely high parallelism between the detected light and the returned light. An angle of 0.1° will generate interference fringes, covering the signal reflected by the target object and causing ranging errors or even failures. Therefore, the light of the FMCW radar needs to be transmitted through a waveguide to accurately control the direction of the light and ensure that the received and transmitted light beams are completely parallel. In this way, the method of changing the light emission direction of the laser cannot be used to increase the field of view angle, resulting in limited horizontal FOV of the FMCW radar and unable to meet the usage requirements in fields such as autonomous driving.

[0004] The content in the background art section is only the technology known to the applicant and does not of course represent the prior art in this field. Summary of the Invention

[0005] In view of at least one defect of the prior art, the present invention provides a laser emitting device, including:

[0006] A transmitting unit configured to sequentially emit multiple continuous lasers with different wavelengths;

[0007] A beam splitting unit disposed downstream of the optical path of the transmitting unit and configured to deflect the multiple continuous lasers with different wavelengths at different angles according to their wavelengths;

[0008] A scanning unit is disposed downstream of the optical path of the beam splitting unit and configured to receive the deflected continuous laser and scan and emit it into the target space to cover a plurality of field of view regions corresponding to the plurality of wavelengths.

[0009] According to one aspect of the present invention, wherein the beam splitting unit includes:

[0010] A plurality of dichroic mirrors are sequentially disposed along the emission direction of the continuous laser. Each dichroic mirror can reflect the continuous laser of a corresponding wavelength incident thereon and transmit the continuous laser of other wavelengths. The wavelengths of the continuous lasers that the plurality of dichroic mirrors can reflect are different.

[0011] According to one aspect of the present invention, wherein the plurality of dichroic mirrors respectively reflect the continuous laser of a corresponding wavelength incident thereon to the scanning unit.

[0012] According to one aspect of the present invention, wherein the total number of the dichroic mirrors is equal to the total number of the wavelengths of the continuous laser.

[0013] According to one aspect of the present invention, wherein the beam splitting unit further includes a reflecting mirror, which is disposed downstream of the optical path of the plurality of dichroic mirrors along the emission direction of the continuous laser and is configured to reflect the continuous laser filtered by the plurality of dichroic mirrors to the scanning unit.

[0014] According to one aspect of the present invention, wherein the total number of the reflecting mirror and the dichroic mirrors is equal to the total number of the wavelengths of the continuous laser.

[0015] According to one aspect of the present invention, wherein the beam splitting unit includes:

[0016] A grating configured to deflect the continuous lasers of the plurality of different wavelengths at different angles;

[0017] A plurality of reflecting mirrors configured to reflect the deflected continuous laser to the scanning unit.

[0018] According to one aspect of the present invention, wherein the emitting unit includes:

[0019] A plurality of light sources configured to generate continuous lasers of a plurality of different wavelengths;

[0020] An optical switch configured to control the sequential passage of the continuous lasers of different wavelengths, and only the laser of one wavelength passes through in each time period.

[0021] According to one aspect of the present invention, wherein the emitting unit is coupled to a waveguide for outputting the continuous laser.

[0022] The present invention also provides an FMCW radar, including the laser emitting device as described above.

[0023] According to one aspect of the present invention, the transmitting unit includes a plurality of light sources configured to generate continuous lasers of a plurality of different wavelengths, and an optical switch configured to control the sequential passage of the continuous lasers of different wavelengths, with only one wavelength of laser passing through in each time period. Among them,

[0024] The switching frequency of the optical switch is the dot frequency of the FMCW radar.

[0025] According to one aspect of the present invention, the FMCW radar further includes a coupler, an amplifier, a circulator, a mixer, and a collimating lens, where:

[0026] The coupler is configured to receive the continuous laser emitted by the transmitting unit and divide it into two beams;

[0027] The amplifier is configured to receive one of the continuous lasers from the coupler, amplify it, and output it to the circulator;

[0028] The circulator is configured to receive the continuous laser output by the amplifier from the first end, output the continuous laser to the collimating lens from the second end, and receive the echo reflected by the target object. The echo is output from the third end of the circulator to the mixer;

[0029] The mixer is configured to receive the other continuous laser from the coupler and the radar echo output from the third end of the circulator, and output a mixed signal after mixing;

[0030] The collimating lens is configured to collimate the continuous laser output by the circulator and then output it to the beam splitting unit.

[0031] According to one aspect of the present invention, the scanning unit is configured to receive the echo and scan it to the beam splitting unit. The beam splitting unit receives the echo and deflects it to the collimating lens, converges it to the circulator through the collimating lens, and is output to the mixer by the circulator.

[0032] According to one aspect of the present invention, the FMCW radar further includes a processing unit configured to receive the mixed signal output by the mixer, perform signal processing to obtain the distance and speed of the target object.

[0033] The present invention also provides a method for detecting using an FMCW radar, including:

[0034] Sequentially emitting continuous lasers of a plurality of different wavelengths through the transmitting unit;

[0035] Deflecting the continuous lasers of the plurality of different wavelengths at different angles according to their wavelengths through the beam splitting unit;

[0036] The scanning unit receives the deflected continuous laser and scans it onto the target space to cover a plurality of field-of-view regions corresponding to the plurality of wavelengths.

[0037] According to one aspect of the present invention, the beam splitting unit includes: a plurality of dichroic mirrors arranged in sequence along the emission direction of the continuous laser, and the method further includes:

[0038] Each dichroic mirror reflects the continuous laser of a corresponding wavelength incident thereon and transmits the continuous laser of other wavelengths, and the plurality of dichroic mirrors respectively reflect the continuous laser of a corresponding wavelength incident thereon to the scanning unit.

[0039] According to one aspect of the present invention, the beam splitting unit further includes: a reflector arranged downstream of the optical paths of the plurality of dichroic mirrors along the emission direction of the continuous laser, and the method further includes:

[0040] The reflector reflects the continuous laser filtered by the plurality of dichroic mirrors to the target space.

[0041] According to one aspect of the present invention, the beam splitting unit includes: a grating and a plurality of reflectors, and the method further includes:

[0042] The grating deflects the continuous lasers of the plurality of different wavelengths at different angles;

[0043] The plurality of reflectors reflect the deflected continuous laser to the scanning unit.

[0044] According to one aspect of the present invention, the transmitting unit includes: a plurality of light sources and an optical switch, and the method further includes:

[0045] The plurality of light sources generate continuous lasers of a plurality of different wavelengths;

[0046] The optical switch controls the sequential passage of the continuous lasers of different wavelengths, and only the continuous laser of one wavelength passes through in each time period. The switching frequency of the optical switch is the point frequency of the FMCW radar.

[0047] According to one aspect of the present invention, the FMCW radar further includes: a coupler, an amplifier, a circulator, a mixer, and a collimating lens, and the method further includes:

[0048] The coupler receives the continuous laser emitted by the transmitting unit and divides it into two beams;

[0049] The amplifier receives one of the two beams of continuous laser from the coupler, amplifies it, and outputs it to the circulator;

[0050] Receive the continuous laser output by the amplifier through the first end of the circulator, output the continuous laser to the collimating lens through the second end of the circulator, and receive the echo reflected by the target object, and output the echo to the mixer through the third end of the circulator;

[0051] Receive another beam of continuous laser from the coupler and the radar echo output from the third end of the circulator through the mixer, and output a mixed signal after mixing;

[0052] Collimate the continuous laser output by the circulator through the collimating lens and then output it to the beam splitting unit.

[0053] According to one aspect of the present invention, the detection method further includes: receiving the echo through the scanning unit and scanning it to the beam splitting unit, deflecting it to the collimating lens through the beam splitting unit, converging it to the circulator through the collimating lens, and outputting it to the mixer by the circulator.

[0054] According to one aspect of the present invention, wherein the FMCW radar further includes a processing unit, and the method further includes:

[0055] Receive the mixed signal output by the mixer through the processing unit for signal processing to obtain the distance and speed of the target object.

[0056] A preferred embodiment of the present invention provides an optical transmitting device for an FMCW radar. By sequentially emitting continuous wave lasers with different wavelengths and deflecting the continuous wave detection signals with different wavelengths to different field of view regions through a beam splitting and scanning device, the detection field of view range of the FMCW radar is expanded, the number of light sources in the FMCW radar is increased, and the limitations of waveguide transmission on the number of light sources and the field of view angle range are overcome. This makes the FMCW radar more suitable for fields such as unmanned driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0058] Figure 1 Schematically shows a laser transmitting device according to a preferred embodiment of the present invention;

[0059] Figure 2 Schematically shows a laser transmitting device according to a preferred embodiment of the present invention;

[0060] Figure 3 Schematically shows a laser transmitting device according to a preferred embodiment of the present invention;

[0061] Figure 4 Schematically shows a laser emission device according to a preferred embodiment of the present invention;

[0062] Figure 5 Schematically shows a laser emission device according to a preferred embodiment of the present invention;

[0063] Figure 6 Schematically shows a transmitting unit according to a preferred embodiment of the present invention;

[0064] Figure 7 Schematically shows a laser emission device according to a preferred embodiment of the present invention;

[0065] Figure 8 Schematically shows by Figure 7 The point cloud map generated by detection by the shown laser emission device;

[0066] Figure 9 Schematically shows a lidar according to a preferred embodiment of the present invention;

[0067] Figure 10 Schematically shows a lidar according to a preferred embodiment of the present invention;

[0068] Figure 11 Schematically shows a lidar according to a preferred embodiment of the present invention;

[0069] Figure 12 Shows a detection method according to a preferred embodiment of the present invention. Detailed implementation manners

[0070] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0071] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0072] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected" and "coupled" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection: it may be a mechanical connection, an electrical connection or a connection capable of mutual communication; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0073] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0074] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0075] Embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the embodiments described herein are only for explaining and illustrating the present invention, and are not intended to limit the present invention.

[0076] According to a preferred embodiment of the present invention, as Figure 1 shown, the present invention provides a laser emitting device 10 for an FMCW radar, including: a transmitting unit 11, a beam splitting unit 12, and a scanning unit 13. The transmitting unit 11 is configured to sequentially emit a plurality of continuous lasers with different wavelengths. As shown in the figure, the wavelengths of the plurality of continuous lasers with different wavelengths are λ1, λ2... λn respectively. The beam splitting unit 12 is disposed downstream of the optical path of the transmitting unit 11 and is configured to deflect the plurality of continuous lasers with different wavelengths at different angles according to their wavelengths. The scanning unit 13 is disposed downstream of the optical path of the beam splitting unit 12, and is configured to receive the deflected continuous laser and scan it out into the target space to cover a plurality of field-of-view regions corresponding to the plurality of wavelengths.

[0077] According to a preferred embodiment of the present invention, as Figure 2 shown, the beam splitting unit 12 includes a plurality of dichroic mirrors 121. The plurality of dichroic mirrors 121 are sequentially disposed along the emission direction of the continuous laser. Each dichroic mirror 121 can reflect a continuous laser with a corresponding wavelength incident thereon and reflect it to the scanning unit 13, and each dichroic mirror 121 transmits the continuous lasers with other wavelengths except the continuous laser with the corresponding wavelength.

[0078] According to a preferred embodiment of the present invention, the number of dichroic mirrors is the same as the number of wavelengths of the continuous lasers with different wavelengths. Each dichroic mirror reflects a continuous laser with one wavelength respectively. By setting the dichroic mirrors at different angles with respect to the laser propagation direction, the lasers with different wavelengths are deflected in different directions.

[0079] According to a preferred embodiment of the present invention, as Figure 2As shown, the beam splitting unit 12 further includes a reflecting mirror 122. The reflecting mirror 122 is arranged downstream of the optical paths of the plurality of dichroic mirrors 121 along the emission direction of the continuous laser, and is configured to reflect the continuous laser filtered by the plurality of dichroic mirrors 121 to the scanning unit 13. The total number of the reflecting mirror 122 and the dichroic mirrors 121 is equal to the total number of the wavelengths of the continuous laser. By arranging each dichroic mirror and the reflecting mirror at different angles with respect to the laser propagation direction, lasers of different wavelengths are deflected in different directions respectively. The technical solution that the beam splitting unit includes a plurality of dichroic mirrors equal in number to the number of wavelengths, and the technical solution that the beam splitting unit includes a plurality of dichroic mirrors and reflecting mirrors with the total number equal to the number of wavelengths are both within the protection scope of the present invention.

[0080] As Figure 3 shown, according to a preferred embodiment of the present invention, the emitting unit 11 uses continuous wave lasers of three light sources with wavelengths of λ1, λ2, and λ3 respectively. The emitting unit 11 sequentially emits continuous wave lasers with wavelengths of λ1, λ2, and λ3 to measure the distance and / or speed of the target object. The dichroic mirror 121-1 only reflects the detection light with a wavelength of λ1. The dichroic mirror 121-1 reflects the detection light with a wavelength of λ1 to the scanning unit 13 and transmits the detection lights with wavelengths of λ2 and λ3. The dichroic mirror 121-2 only reflects the detection light with a wavelength of λ2 (it is also possible to set the dichroic mirror 121-2 to reflect the detection lights with wavelengths of λ1 and λ2, but since the dichroic mirror 121-1 has already reflected the detection light with a wavelength of λ1, only the detection lights with wavelengths of λ2 and λ3 reach the dichroic mirror 121-2). The dichroic mirror 121-2 reflects the detection light with a wavelength of λ2 to the scanning unit 13 and transmits the detection light with a wavelength of λ3. The reflecting mirror 122 is arranged downstream of the optical paths of the dichroic mirror 121-1 and the dichroic mirror 121-2. The detection light with a wavelength of λ3 can pass through the two dichroic mirrors 121-1 and 121-2 and then be incident on the reflecting mirror 122. The detection light with a wavelength of λ3 is reflected by the reflecting mirror 122 to the scanning unit 13. The three-way detection lights are all guided to the scanning unit 13 and are emitted after being reflected by the scanning unit 13. The emitting unit 11 sequentially emits three-way detection lights. After the three-way detection lights are sequentially guided to the scanning unit 13, they are emitted to the target space at different angles to detect the target object in the target space.

[0081] Within one rotation period of the scanning unit 13, the three-way detection light can cover a wider field of view compared to single-light-source detection. Preferably, by sequentially splicing the horizontal field-of-view regions corresponding to the three-way detection light, a detection range three times that of the single-light-source detection field-of-view region is obtained. By adjusting the angles of the dichroic mirrors 121-1, dichroic mirrors 121-2, and the reflecting mirror 122, the angle control of the emitted light of different light sources (i.e., continuous-wave lasers corresponding to different wavelengths) can be achieved. For example, within one rotation period of the scanning unit 13, the detection light corresponding to one light source can cover a horizontal field of view (FOV) of 40° after being reflected multiple times at different angles of the scanning unit 13. When three light sources are incident on the scanning unit 13 at different angles respectively, they can be reflected by the scanning unit 13 to different horizontal FOV regions. The horizontal FOVs corresponding to the three light sources are sequentially spliced to achieve a large horizontal-angle field-of-view detection of 120°.

[0082] Optionally, there can be a certain overlap between adjacent two FOV regions to ensure the continuity of the scanning field of view. For example, taking the forward direction of the radar as the horizontal 0° field of view, the continuous laser of one wavelength can be reflected to the horizontal field of view from -20° to 20° as the scanning unit 13 rotates, and the continuous laser of another wavelength can be reflected by the scanning unit to the horizontal field of view from 15° to 55°.

[0083] Among them, the scanning unit 13 preferably includes one or more of a two-dimensional galvanometer, a swing mirror, and a rotating mirror.

[0084] According to a preferred embodiment of the present invention, as Figure 4 shown, the beam splitting unit 12 includes a grating 123 and a plurality of reflecting mirrors 122. The grating 123 is configured to deflect continuous lasers of multiple different wavelengths at different angles. The plurality of reflecting mirrors 122 are configured to reflect the deflected continuous lasers to the scanning unit 13.

[0085] From the grating equation: d(sinα + sinβ) = mλ, it can be known that for the same spectral order m, incident lights of different wavelengths λ1, λ2, λ3 projected onto the grating at the same incident angle α have diffracted lights exiting at different diffraction angles β. This shows that for a given grating, the different wavelength spectral lines in the same-order grating spectrum do not overlap, but are arranged in the order of wavelength, forming a series of discrete spectral lines. In this way, the composite light of various different wavelengths mixed together is separated from each other after being diffracted by the grating, achieving beam splitting.

[0086] By setting the grating 123, the detection lights of different wavelengths can be made to exit in different directions. According to a preferred embodiment of the present invention, as Figure 5As shown in the figure, mirrors 122-1, 122-2, and 122-3 are respectively arranged along the light-emitting sides of the diffracted lights with three wavelengths of λ1, λ2, and λ3 of the grating 123, and the detection lights are respectively guided to the scanning unit 13. The emitting unit 11 sequentially emits continuous-wave lasers with three different wavelengths to measure the distance and / or speed of the target object. The detection lights with three different wavelengths are incident on the grating 123 and exit at three different diffraction angles. Mirrors 122-1, 122-2, and 122-3 are arranged downstream of the optical paths of the diffracted lights in three different directions to respectively reflect the diffracted lights in the three directions to the scanning unit 13. Since the detection lights with three different wavelengths are incident on the scanning unit 13 at different angles, the scanning unit 13 can reflect them to different field-of-view regions.

[0087] According to a preferred embodiment of the present invention, after the detection light of one wavelength exits through the grating 123, it directly irradiates the surface of the scanning unit 13, while the grating 123 deflects the detection lights of other different wavelengths at different angles. A plurality of mirrors 122 are sequentially arranged on the optical paths of the diffracted lights of other different wavelengths, and the mirrors 122 reflect them to the scanning unit 13. Such an embodiment is also within the protection scope of the present invention. For example, after the detection light with wavelength λ1 passes through the grating 123 and is deflected, it directly irradiates the surface of the scanning unit 13, while the grating 123 deflects the detection lights with wavelengths λ2 and λ3 at different angles. A mirror 122-1 is arranged on the optical path of the detection light with wavelength λ2, and a mirror 122-2 is arranged on the optical path of the detection light with wavelength λ3. The mirror 122-1 and the mirror 122-2 reflect the detection light with wavelength λ2 and the detection light with wavelength λ3 to the scanning unit 13 at different angles.

[0088] Those skilled in the art can easily understand that Figure 4 and Figure 5 in the embodiments, the grating 123 is a transmissive grating, and the detection lights with different wavelengths are deflected in sequence by a reflective grating, which is also within the protection scope of the present invention.

[0089] According to a preferred embodiment of the present invention, as Figure 6 shown in the figure, the emitting unit 11 includes: a plurality of light sources 111 and an optical switch 112. The plurality of light sources 111 are configured to generate continuous lasers with a plurality of different wavelengths, such as continuous-wave lasers with wavelengths of λ1, λ2... λn as shown in the figure. The optical switch 112 is configured to be coupled with the plurality of light sources 111 respectively, and only one wavelength of continuous laser can pass through each time period. For example, the continuous lasers with different wavelengths can be controlled to pass through in sequence at a certain time interval.

[0090] The FMCW radar uses a narrow linewidth laser with a modulation bandwidth of several Hz, and the current needs to be kept stable. Therefore, the laser is in a stable state of continuous light emission, and it is not suitable to control the light emission state by turning the driving current on and off. Therefore, the light output can only be controlled by an optical switch. For example, using optical switch devices such as liquid crystal shutters, light valves, and digital microlens arrays, which are all mature devices in silicon photonics technology and do not increase additional costs. Usually, the response speed of the optical switch device is about 200 ns, which can meet the requirements of the light source switching speed.

[0091] According to a preferred embodiment of the present invention, the switching frequency of the optical switch 112 is the point frequency of the FMCW radar. That is, the laser of a certain wavelength passes through the optical switch 112 and is divided into two parts: local oscillator light and detection light. The local oscillator light is output to a mixer (not shown in the figure), and the detection light is emitted after the direction is adjusted by the beam splitting unit 12 and the scanning unit 13. The echo light obtained by reflecting the detection light from the target object is also introduced into the mixer after passing through the scanning unit 13 and the beam splitting unit 12, and is mixed with the local oscillator light to obtain a beat frequency signal for subsequent calculation of the distance and / or speed of the target object. After one detection is completed, the optical switch 112 switches, so that the laser of another wavelength passes through the optical switch 112 and is emitted, and scanning sampling is performed at another angle. By repeating the above steps, lasers of different wavelengths can be sequentially scanned and sampled.

[0092] According to a preferred embodiment of the present invention, as Figure 7 shown, the transmitting unit 11 uses three light sources 111. Let the wavelengths of the continuous wave lasers emitted by the three light sources 111 be λ1, λ2, and λ3 respectively. The three-way light is all connected to the 3×1 optical switch 112. The 3×1 optical switch 112 controls the light of wavelengths λ1, λ2, and λ3 to pass through in sequence for ranging and / or speed measurement. Only one-way light passes through each time, and the switching time is one point frequency period.

[0093] For example, the light output side of the optical switch is provided with light output ports 1 / 2 / 3 having the same number as the light sources. Each light output port is coupled to the output path through a waveguide to output the detection light to the beam splitting unit.

[0094] Within the same sampling period, the transmitting unit 11 sequentially emits continuous wave lasers of three different wavelengths, which are deflected in different angles in sequence through the beam splitting unit 12 and scanned by the scanning unit 13 towards the target area, and are sequentially emitted towards different field of view areas. Figure 8 Schematically shows the scanning field of view and sampling point distribution corresponding to three different wavelength light sources.

[0095] As Figure 8 shown, taking the due forward direction of the radar as the horizontal 0° field of view, then Figure 8The detection light with wavelength λ1 as shown is reflected to a field of view of -60 to 20° under the scanning action of the scanning unit 13, the detection light with wavelength λ2 is reflected by the scanning unit 13 to a field of view of -20° to 20°, and the detection light with wavelength λ3 is reflected by the scanning unit 13 to a field of view of 20° to 60°.

[0096] Figure 7 In the embodiment of , the 3×1 optical switch 112 controls the detection light with wavelength λ1 to pass through. After being deflected by the beam splitting unit 12 and scanned by the scanning unit 13, the echo reflected by the target object of the detection light with wavelength λ1 is received, sampled and processed to generate the sampling point λ1-1. After completing one sampling, the 3×1 optical switch 112 controls the detection light with wavelength λ2 to pass through, and performs a second sampling and processing on the echo to generate the sampling point λ2-1.

[0097] In a preferred embodiment, the switching speed of the three light sources is very fast (one sampling period). It can be considered that after the detection light with wavelength λ1 is reflected by the scanning unit 13, during the period from when the detection light with wavelength λ1 is reflected until the detection light with wavelength λ2 is incident on the scanning unit 13, the scanning unit 13 is basically in an instantaneous position. The three-wavelength light beams are deflected to different field-of-view scanning points almost simultaneously because of different incident angles; rather than relying on the scanning unit to sequentially sweep through three angles and deflect the light beams with different wavelengths by different angles. The main function of the scanning unit is to make the detection light beam at each wavelength scan within the corresponding field of view range along a certain path to obtain a two-dimensional field of view.

[0098] For example, in one sampling period (the detection light with wavelengths λ1-λ3 is sampled cyclically once), the lidar performs a detection sampling in three fields of view respectively. In the second period, the detection light is deflected by a certain angle under the action of the scanning unit 13. As Figure 8 shown, the sampling points generated in sequence according to the scanning order are: λ1-1, λ2-1, λ3-1, λ1-2, λ2-2, λ3-2... The time interval between generating the sampling point λ1-2 and generating the sampling point λ1-1 is the same as the time interval between generating the sampling point λ2-2 and generating the sampling point λ2-1, and the time interval between generating the sampling point λ3-2 and generating the sampling point λ3-1. Therefore, the scanning point intervals in different periods within the same 40° field of view range are uniform, and uniform scanning of the entire field of view can be achieved. The detection of multiple periods is superimposed to achieve ranging and / or velocity measurement within the complete 120° field of view range.

[0099] According to a preferred embodiment of the present invention, the present invention further provides an FMCW radar 20, including the laser emitting device 10 as described above.

[0100] According to a preferred embodiment of the present invention, as Figure 9As shown, the FMCW radar 20 further includes a coupler 21, an amplifier 22, a circulator 23, a mixer 24, and a collimating lens 25. The coupler 21 is configured to receive the continuous laser emitted by the transmitting unit 11 and divide it into two beams. The amplifier 22 is configured to receive one of the continuous laser beams from the coupler 21, amplify it, and output it to the circulator 23. The circulator 23 is configured to receive the continuous laser output from the amplifier 22 at the first end, output the continuous laser to the collimating lens 25 at the second end, and receive the echo reflected by the target object. The echo is output from the third end of the circulator 23 to the mixer 24. The mixer 24 is configured to receive the other continuous laser beam from the coupler 21 and the radar echo output from the third end of the circulator 23, mix them, and output a mixed signal. The collimating lens 25 is configured to collimate the continuous laser output from the circulator 23 and output it to the beam splitting unit 13.

[0101] According to a preferred embodiment of the present invention, the scanning unit 13 is configured to receive the radar echo and scan it to the beam splitting unit 12. The beam splitting unit 12 receives the echo and deflects it to the collimating lens 25. The collimating lens 25 focuses it onto the circulator 23, and it is output from the circulator 23 to the mixer 24.

[0102] As Figure 10As shown, according to a preferred embodiment of the present invention, the transmitting unit 11 with three light sources 111 sequentially passes the detection light of one wavelength through the 3×1 optical switch 112. A part of the detection light is introduced into the mixer (PD) 24 by the optical coupler 21 as the local oscillator light, and the other part is amplified by the amplifier (preferably an erbium-doped fiber amplifier, EDFA) 22, exits through the circulator 23 (which can also be other coupling devices, such as a semi-transmissive and semi-reflective mirror, all within the protection scope of the present invention), and is incident on the surface of the dichroic mirror 121-1 after being collimated by the lens 25. The dichroic mirror 121-1 only reflects the detection light with a wavelength of λ1; the dichroic mirror 121-2 only reflects the detection light with a wavelength of λ2 (it can also reflect the detection lights with wavelengths of λ1 and λ2, but since the dichroic mirror 121-1 has reflected the detection light with a wavelength of λ1, only the detection lights with wavelengths of λ2 and λ3 reach the dichroic mirror 121-2), and the detection light with a wavelength of λ3 can pass through the two dichroic mirrors 121 and then be incident on the reflector 122. The three beams of light are all directed to the scanning unit 13 and exit after being reflected by the scanning unit 13. By adjusting the angles of the two dichroic mirrors 121 and the reflector 122, the angle control of the light emitted from different light sources can be achieved; each light source corresponds to a horizontal field of view (FOV) of 40°, and the fields of view generated by the three light sources are sequentially spliced to reach a complete detection range of 120°. The reflected light of the target object is coaxial with the detection beam, is introduced into the mixer 24 by the scanning unit 13, the dichroic mirror 121, the lens 25 and the circulator 23, and is mixed with the local oscillator light to output a mixed signal. Fourier transform and the calculation of the distance and speed of the target object are performed, and the calculation function is implemented by the IC chip at the receiving end.

[0103] As Figure 11 shown, according to another preferred embodiment of the present invention, the beam splitting unit 12 can also be realized by the grating 123 and the reflectors 122-1, 122-2 and 122-3. The detection process of the FMCW radar 20 is substantially the same as that of the previous embodiment and will not be elaborated here.

[0104] According to a preferred embodiment of the present invention, the FMCW radar 20 further includes a processing unit 26 configured to receive the mixed signal output by the mixer 24 and perform signal processing to obtain the distance and speed of the target object.

[0105] It is easy to think that according to the detection requirements of different application scenarios of the radar, the detection lights of different wavelengths can also be deflected to different angles in the vertical direction and incident on the scanning unit, so as to realize the splicing of multiple angular fields of view in the vertical direction.

[0106] According to a preferred embodiment of the present invention, as Figure 12 shown, the present invention also provides a detection method 30 using the FMCW radar 20 as described above, including:

[0107] In step S301, a plurality of continuous lasers with different wavelengths are sequentially emitted by the emitting unit 11;

[0108] In step S302, the plurality of continuous lasers with different wavelengths are deflected at different angles according to their wavelengths by the beam splitting unit 12;

[0109] In step S303, the deflected continuous lasers are received by the scanning unit 13 and scanned out into the target space to cover a plurality of field of view regions corresponding to the plurality of wavelengths.

[0110] According to a preferred embodiment of the present invention, the beam splitting unit 12 includes: a plurality of dichroic mirrors 121, and the plurality of dichroic mirrors 121 are sequentially arranged along the emission direction of the continuous laser. The method 30 further includes:

[0111] Each dichroic mirror 121 reflects a continuous laser of a corresponding wavelength incident thereon and transmits continuous lasers of other wavelengths.

[0112] According to a preferred embodiment of the present invention, the detection method 30 further includes: reflecting a continuous laser of a corresponding wavelength incident on the plurality of dichroic mirrors 121 to the scanning unit 13 through the plurality of dichroic mirrors 121.

[0113] According to a preferred embodiment of the present invention, the beam splitting unit 12 further includes: a reflecting mirror 122, and the reflecting mirror 122 is arranged downstream of the optical paths of the plurality of dichroic mirrors 121 along the emission direction of the continuous laser. The method 30 further includes:

[0114] The reflecting mirror 122 reflects the continuous laser filtered by the plurality of dichroic mirrors 121 to the target space.

[0115] According to a preferred embodiment of the present invention, the beam splitting unit 12 includes: a grating 123 and a plurality of reflecting mirrors 122. The method 30 further includes:

[0116] The grating 123 deflects the plurality of continuous lasers with different wavelengths at different angles;

[0117] The deflected continuous lasers are reflected to the scanning unit 13 by the plurality of reflecting mirrors 122.

[0118] According to a preferred embodiment of the present invention, the emitting unit 11 includes: a plurality of light sources 111 and an optical switch 112. The method 30 further includes:

[0119] A plurality of continuous lasers with different wavelengths are generated by the plurality of light sources 111;

[0120] The continuous laser of different wavelengths is controlled to pass through in sequence by the optical switch 112, and only the continuous laser of one wavelength passes through in each time period. The switching frequency of the optical switch 112 is the point frequency of the FMCW radar 20.

[0121] According to a preferred embodiment of the present invention, the scanning frequency of the scanning unit 13 is lower than the switching frequency of the optical switch 112, so that within the same period of sequentially emitting continuous lasers of multiple wavelengths by the transmitting unit 11, the deflection angle of the scanning unit 13 remains substantially unchanged.

[0122] According to a preferred embodiment of the present invention, the FMCW radar 20 further includes: a coupler 21, an amplifier 22, a circulator 23, a mixer 24, and a collimating lens 25. The method 30 further includes:

[0123] Receiving the continuous laser emitted by the transmitting unit 11 through the coupler 21 and splitting it into two beams;

[0124] Receiving one of the continuous laser beams from the coupler 21 through the amplifier 22, amplifying it and then outputting it to the circulator 23;

[0125] Receiving the continuous laser output by the amplifier 22 through the first end of the circulator 23, outputting the continuous laser to the collimating lens 25 through the second end of the circulator 23, receiving the echo reflected by the target object, and outputting the radar echo to the mixer 24 through the third end of the circulator 23;

[0126] Receiving the other continuous laser beam from the coupler 21 and the radar echo output from the third end of the circulator 23 through the mixer 24, mixing them and then outputting a mixed signal;

[0127] Collimating the continuous laser output by the circulator 23 through the collimating lens 25 and then outputting it to the beam splitting unit 12.

[0128] According to a preferred embodiment of the present invention, the detection method 30 further includes: receiving the radar echo through the scanning unit 13, scanning it to the beam splitting unit 12, deflecting it to the collimating lens 25 by the beam splitting unit 12, converging it to the circulator 23 by the collimating lens 25, and outputting it to the mixer 24 by the circulator 23.

[0129] According to a preferred embodiment of the present invention, the FMCW radar 20 further includes a processing unit. The method 30 further includes:

[0130] Receiving the mixed signal output by the mixer 24 through the processing unit for signal processing to obtain the distance and speed of the target object.

[0131] Preferred embodiments of the present invention provide a laser emission device. By sequentially emitting continuous-wave lasers of different wavelengths and deflecting the continuous-wave detection signals of different wavelengths to different field-of-view regions through a beam splitting and scanning device, the detection field-of-view of the radar is expanded. When applied to an FMCW radar, the number of light sources in the FMCW radar can be increased, overcoming the limitations of waveguide transmission on the light source and the field-of-view, making the FMCW radar more suitable for fields such as driverless driving.

[0132] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A laser emission device, comprising: An emission unit configured to sequentially emit multiple continuous lasers with different wavelengths; A beam splitting unit disposed downstream of the optical path of the emission unit and configured to deflect and reflect the multiple continuous lasers with different wavelengths at different angles according to their wavelengths to a scanning unit; A scanning unit disposed downstream of the optical path of the beam splitting unit, configured to receive the deflected continuous laser and scan it out into a target space to cover multiple field of view regions corresponding to the multiple wavelengths, Wherein the beam splitting unit includes: Multiple dichroic mirrors, the multiple dichroic mirrors are sequentially arranged along the emission direction of the continuous laser, wherein each dichroic mirror can reflect a continuous laser of a corresponding wavelength incident thereon and transmit continuous lasers of other wavelengths, and the wavelengths of the continuous lasers that the multiple dichroic mirrors can reflect are different.

2. The laser emission device according to claim 1, wherein the multiple dichroic mirrors respectively reflect a continuous laser of a corresponding wavelength incident thereon to the scanning unit.

3. The laser emission device according to claim 2, wherein the total number of the dichroic mirrors is equal to the total number of the wavelengths of the continuous laser.

4. The laser emission device according to claim 1, wherein the beam splitting unit further includes a reflector, the reflector is disposed downstream of the optical path of the multiple dichroic mirrors along the emission direction of the continuous laser, and is configured to reflect the continuous laser filtered by the multiple dichroic mirrors to the scanning unit.

5. The laser emission device according to claim 4, wherein the total number of the reflector and the dichroic mirrors is equal to the total number of the wavelengths of the continuous laser.

6. The laser emission device according to any one of claims 1-5, wherein the emission unit includes: Multiple light sources configured to generate multiple continuous lasers with different wavelengths; An optical switch configured to control the sequential passage of the continuous lasers with different wavelengths, and only one wavelength of laser passes through in each time period.

7. The laser emission device according to any one of claims 1-5, wherein the emission unit is coupled to a waveguide for outputting the continuous laser.

8. An FMCW radar, comprising the laser emission device according to any one of claims 1-7.

9. The FMCW radar according to claim 8, wherein the emission unit includes multiple light sources configured to generate multiple continuous lasers with different wavelengths, and an optical switch configured to control the sequential passage of the continuous lasers with different wavelengths, and only one wavelength of laser passes through in each time period, wherein, The switching frequency of the optical switch is the point frequency of the FMCW radar.

10. The FMCW radar according to claim 8 or 9, further comprising a coupler, an amplifier, a circulator, a mixer and a collimating lens, wherein: The coupler is configured to receive the continuous laser emitted by the emission unit and divide it into two beams; The amplifier is configured to receive one of the two beams of continuous laser from the coupler, amplify it and output it to the circulator; The circulator is configured to receive the continuous laser output from the amplifier at a first end, output the continuous laser to the collimating lens at a second end, and receive the echo reflected by the target, and output the echo to the mixer through a third end of the circulator; The mixer is configured to receive another beam of continuous laser from the coupler and the radar echo output from the third end of the circulator, and output a mixed signal after mixing; The collimating lens is configured to collimate the continuous laser output from the circulator and then output it to the beam splitting unit.

11. The FMCW radar according to claim 10, wherein the scanning unit is configured to receive the echo and scan it to the beam splitting unit, the beam splitting unit receives the echo and deflects it to the collimating lens, converges it through the collimating lens to the circulator, and outputs it to the mixer through the circulator.

12. The FMCW radar according to claim 11, further comprising a processing unit configured to receive the mixed signal output from the mixer and perform signal processing to obtain the distance and speed of the target.

13. A method for detecting using an FMCW radar, comprising: Sequentially emitting a plurality of continuous lasers with different wavelengths through a transmitting unit; Deflecting and reflecting the plurality of continuous lasers with different wavelengths at different angles according to their wavelengths to a scanning unit through a beam splitting unit, wherein the beam splitting unit includes a plurality of dichroic mirrors, the plurality of dichroic mirrors are sequentially arranged along the emission direction of the continuous laser, each dichroic mirror reflects a corresponding wavelength of the continuous laser incident thereon and transmits the continuous lasers with other wavelengths, and the plurality of dichroic mirrors respectively reflect a corresponding wavelength of the continuous laser incident thereon to the scanning unit; Receiving the deflected continuous laser through the scanning unit and scanning it out into the target space to cover a plurality of field of view regions corresponding to the plurality of wavelengths.

14. The detection method according to claim 13, wherein the spectroscopic unit further comprises: A reflector, the reflector is arranged downstream of the optical paths of the plurality of dichroic mirrors along the emission direction of the continuous laser, and the method further includes: Reflecting the continuous laser filtered by the plurality of dichroic mirrors to the target space through the reflector.

15. The detection method according to any one of claims 13-14, wherein the transmitting unit comprises: A plurality of light sources and an optical switch, and the method further includes: Generating a plurality of continuous lasers with different wavelengths through the plurality of light sources; Controlling the sequential passing of the continuous lasers with different wavelengths through the optical switch, and only one wavelength of continuous laser passes through in each time period, and the switching frequency of the optical switch is the point frequency of the FMCW radar.

16. The detection method according to any one of claims 13-14, wherein the FMCW radar further comprises: A coupler, an amplifier, a circulator, a mixer and a collimating lens, and the method further includes: Receiving the continuous laser emitted by the transmitting unit through the coupler and splitting it into two beams; Receiving one of the two beams of continuous laser from the coupler through the amplifier, amplifying it and then outputting it to the circulator; Receiving the continuous laser output from the amplifier through a first end of the circulator, outputting the continuous laser to the collimating lens through a second end of the circulator, and receiving the echo reflected by the target, and outputting the echo to the mixer through a third end of the circulator; Receive another continuous laser from the coupler through the mixer and the radar echo output from the third end of the circulator, and output a mixed signal after mixing; Collimate the continuous laser output from the circulator through the collimating lens and then output it to the beam splitting unit.

17. The detection method according to claim 16 further includes: Receive the echo through the scanning unit and scan it to the beam splitting unit, deflect it to the collimating lens through the beam splitting unit, converge it to the circulator through the collimating lens, and output it to the mixer through the circulator.

18. The detection method according to claim 17, wherein the FMCW radar further comprises a processing unit, and the method further comprises: Receive the mixed signal output from the mixer through the processing unit for signal processing to obtain the distance and speed of the target object.

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