WO2023240341A1

WO2023240341A1 - Apparatus for hybrid field of view in a lidar system

Info

Publication number: WO2023240341A1
Application number: PCT/CA2023/050811
Authority: WO
Inventors: Robert Baribault; Siegwart Bogatscher; Andreas HOELLDORFER; Dominique BODZIANI; Nico Heussner
Original assignee: Leddartech Inc
Priority date: 2022-06-14
Filing date: 2023-06-13
Publication date: 2023-12-21

Abstract

An apparatus is used in a LIDAR system. The apparatus comprises a transmitting path. The transmitting path comprises a laser, a polarizing beam splitter (PBS), and a beam-steering device. The laser emits a plurality of beams. The PBS splits the plurality of beams into a first plurality of beams each of which has a first polarization and a second plurality of beams each of which has a second polarization and to generate the second plurality of beams in a second field of view (FOV). The beam-steering device receives the first plurality of beams and steers the first plurality of beams in a first FOV.

Description

APPARATUS FOR HYBRID FIELD OF VIEW IN A LIDAR SYSTEM

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of U.S. Provisional Application Serial No. 63/35,1981, filed on June 14, 2022, hereby incorporated by reference herein.

FIELD

[0002] The present disclosure relates generally to light detection and ranging (LIDAR.) systems and, more particularly, to apparatus for generating beams in a hybrid field of view (FOV) in such systems.

BACKGROUND

[0003] LIDAR systems are widely used in various applications that have high- resolution demands, for example including autonomous vehicles, agriculture, archaeology, geology, etc. Taking automotive and mobility applications as an example, LIDAR systems enable obstacle detection, avoidance, and safe navigation to be achieved with high accuracy and sufficient resolutions. In particular, when a LIDAR system is employed in such applications, the LIDAR system can image an angle within a field of view (FOV) and locate objects within the FOV. The FOV, an angle covered by the LIDAR system or an angle in which beams are emitted by the LIDAR system, is the maximum area of a sample that the LIDAR system can image. The FOV is determined by a focal length of a lens of the LIDAR system and a sensor size of the LIDAR system. In autonomous vehicle applications, as beams are emitted in the FOV to capture an object within the FOV, transmission efficiency and scanning accuracy may be reduced significantly in a central region of a desired FOV because power density of beams is low in the central region of the desired FOV.

[0004] Furthermore, in order to improve scanning range in the autonomous vehicle application, such as in an autonomous vehicle, multiple LIDAR devices may be utilized so that objects can be captured in different respective FOVs. Although a large number of LIDAR, devices can be utilized to offer high range accuracy, hardware costs may increase as multiple LIDAR devices are needed.

[0005] Accordingly, it is desirable to use an apparatus to generate two or more FOVs within a single LIDAR system without causing excessive changes to the LIDAR system.

SUMMARY

[0006] The present disclosure describes an apparatus for use in a light detection and ranging (LIDAR) system. The apparatus comprises a transmitting (Tx) path, which incorporates a laser, a polarizing beam splitter (PBS), and a beam-steering device. The PBS splits the plurality of beams emitted by the laser into a first plurality of beams each of which has a first polarization and a second plurality of beams each of which has a second polarization. The beam-steering device steers the first plurality of beams in a first field of view (FOV). The PBS outputs the second plurality of beams in the second FOV. As the second plurality of beams are scanned within the second FOV, which is a relatively small region in the center of a desired FOV of the LIDAR system, power density of beams in the second FOV may be improved significantly. Therefore, transmission efficiency in the second FOV (e.g., at a central region of the desired FOV) may be boosted.

[0007] In some examples, a mirror is added after the PBS in the Tx path. In the Tx path, the mirror receives the second plurality of beams from the PBS and reflects the second plurality of beams in the second FOV. A placement angle of the mirror is controllable such that a rotation of the second FOV may be altered in accordance with the placement angle of the mirror.

[0008] In some applications, the apparatus further comprises one or more beam splitter which is connected to the PBS. Therefore, the second plurality of beams are split into a third plurality of beams and a fourth plurality of beams. The mirror scans the third plurality of beams in a third FOV, and the beam splitter scans the fourth plurality of beams in a fourth FOV. Each of the third FOV and the fourth FOV is half of the second FOV. In other possible configurations, a range of the third FOV equals to that of the fourth FOV, which is identical to a range of the second FOV. Such configuration also helps to improve transmission efficiency at the central region of the desired FOV.

[0009] In various non-limiting embodiments of the present disclosure, the apparatus may include two or more receiving path each of which receives beams in a respective FOV. In some examples, one receiving path may receive beams in the desired FOV.

[0010] According to a first example aspect is an apparatus for use in a LIDAR, system. The apparatus comprises a transmitting path. The transmitting path includes a laser configured to emit a plurality of beams, a polarizing beam splitter (PBS) configured to split the plurality of beams into a first plurality of beams each of which has a first polarization and a second plurality of beams each of which has a second polarization and to generate the second plurality of beams in a second field of view (FOV); and a beam-steering device configured to receive the first plurality of beams and to steer the first plurality of beams in a first FOV.

[0011] In accordance with the preceding aspects, the first FOV plus the second FOV equals to a desired FOV of the LIDAR system aspect.

[0012] In accordance with any of the preceding aspects, an optical device is configured to receive the second plurality of beams from the PBS and to steer the second plurality of beams in the second FOV.

[0013] In accordance with any of the preceding aspects, the apparatus further comprises a depolarizer. The depolarizer is configured to receive the plurality of beams, to change polarizations of the plurality of beams, and to output the first plurality of beams each with the first polarization and the second plurality of beams each of the second polarization, wherein a cardinality of the first plurality equals to that of the second plurality.

[0014] In accordance with any of the preceding aspects, the apparatus further comprises an optical collimator configured to receive the plurality of beams and to generate a plurality of collimated beams. [0015] In accordance with any of the preceding aspects, the optical device includes a mirror.

[0016] In accordance with any of the preceding aspects, the mirror is placed 45° with respect to x axis that is parallel to a central area of a desired FOV, and the second FOV is at a central region of a desired FOV of the LIDAR, system.

[0017] In accordance with any of the preceding aspects, the apparatus further comprises telescope optics configured to receive the second plurality of beams and to focus the second plurality of beams in a third FOV, wherein the third FOV is narrower than the second FOV.

[0018] In accordance with any of the preceding aspects, the apparatus further comprises a beam splitter configured to receive the second plurality of beams from the PBS and to split the second plurality of beams into a third plurality of beams and a fourth plurality of beams. The optical device is configured to receive the third plurality of beams and to generate the third plurality of beams in a third FOV; and the beam splitter is further configured to generate the fourth plurality of beams in a fourth FOV.

[0019] In accordance with any of the preceding aspects, each of the third FOV and the fourth FOV is half of the second FOV.

[0020] In accordance with any of the preceding aspects, the third FOV is equal to the fourth FOV, which is identical to the second FOV.

[0021] In accordance with any of the preceding aspects, the apparatus further comprises a first wedge configured to receive the third plurality of beams from the optical device and to further control angles of the third plurality of beams in the third FOV; and a second wedge configured to receive the fourth plurality of beams from the beam splitter and to further control angles of the fourth plurality of beams in the fourth FOV. [0022] In accordance with any of the preceding aspects, a placement angle of the optical device is controllable to alter the second FOV.

[0023] In accordance with any of the preceding aspects, a placement angle of the beam-steering device is controllable to alter the first FOV.

[0024] In accordance with any of the preceding aspects, the apparatus further comprises first beam spreading optics configured to receive the first plurality of beams in the first FOV and to spread the first plurality of beams in a FOV that is greater than the first FOV; and second beam spreading optics configured to receive the second plurality of beams in the second FOV and to spread the second plurality of beams in a FOV that is greater than the second FOV.

[0025] In accordance with any of the preceding aspects, the apparatus further comprises a first receiving path including a first receiver configured to receive the first plurality of beams in the first FOV and the second in the second FOV; and a second receiving path including a second receiver configured to receive the second plurality of beams in the second FOV.

[0026] In accordance with any of the preceding aspects, the optical device includes another beam-steering device.

[0027] In accordance with any of the preceding aspects, the first FOV and the second FOV constitute a hybrid FOV for the LIDAR, system.

[0028] According to a second example aspect is an apparatus for use in a LIDAR system. The apparatus comprises a laser configured to emit a plurality of beams, a first optical device configured to split the plurality of beams into a first, second, and third plurality of beams and to generate the first plurality of beams in a first FOV and the second plurality of beams in a second FOV, wherein a range of the first FOV is identical to that of the second FOV; and a beam-steering device configured to receive the third plurality of beams and to steer the third plurality of beams in a third FOV.

[0029] In accordance with any of the preceding aspects, the first optical device includes an optical glass X-cube.

[0030] In accordance with any of the preceding aspects, the apparatus further comprises an optical collimator configured to receive the plurality of beams and to generate a plurality of collimated beams.

[0031] In accordance with any of the preceding aspects, a depolarizer is configured to receive the plurality of beams to change polarizations of the plurality of beams, and to output the first plurality of beams each with a second polarization, the second plurality of beams each with the second polarization, and the third plurality of beams each with a first polarization.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Reference will now be made, by way of example, to the accompanying drawings which show example embodiments of the present application, and in which:

[0033] FIG. 1 is a schematic diagram of an example LIDAR system;

[0034] FIG.2A is a schematic diagram illustrating an example transmitting (Tx) path of the LIDAR system of FIG.l;

[0035] FIG.2B is a schematic diagram illustrating an alternative Tx path of the LIDAR system of FIG.l;

[0036] FIG.2C is a schematic diagram illustrating another alternative Tx path of the LIDAR system of FIG.l;

[0037] FIG.2D is a schematic diagram illustrating another alternative Tx path of the LIDAR system of FIG. 1;

[0038] FIG.2E is a schematic diagram illustrating another alternative Tx path of the LIDAR system of FIG.l; [0039] FIG.2F is a schematic diagram illustrating another alternative Tx path of the LIDAR, system of FIG.l;

[0040] FIG.3A is a schematic diagram illustrating an example transmitting (Tx) path of the LIDAR system of FIG.l;

[0041] FIG.3B is a schematic diagram illustrating an alternative Tx path of the LIDAR system of FIG.l;

[0042] FIG.3C is a schematic diagram illustrating another alternative Tx path of the LIDAR system of FIG.l;

[0043] FIG.4 is a schematic diagram illustrating a receiving (Rx) path of the LIDAR system of FIG.l;

[0044] Similar reference numerals may have been used in different figures to denote similar components.

DESCRIPTION OF EXAMPLE EMBODIMENTS

[0045] Similar reference numerals may have been used in different figures to denote similar components.

[0046] FIG. 1 illustrates an example LIDAR system 100 in accordance with an example embodiment. The LIDAR system 100 includes a transmitting (Tx) path 101, a receiving (Rx) path 103, and a controller 108. The transmitting path 101 comprises a transmitting stage 102 and at least one beam-steering device 106(1). The receiving path 103 includes at least a receiving stage 104. The receiving stage 104 of the receiving path 103 includes an optical receiver 1042 (also referred to as a detector), which may include an avalanche photodiode (AD). In the transmitting path 101, the transmitting stage 102 includes a laser 1022, which simultaneously emits a plurality of beams (also called laser pulses or optical light pulses) each of which has a duration (e.g., typically in the nanosecond (ns) range). The beam-steering devices 106(1) receives the emitted beams (also referred to incident lights or incident beams) from the laser 1022 and then steers the beams to scan objects in a FOV. The beams travel to the objects and are reflected back or backscattered. The reflected beams are received by the receiving path 103 where the receiving stage 104 receives the backscattered or reflected beams and the optical receiver 1042 detects the reflected beams. Once the optical receiver 1042 detects the reflected or backscattered beams, other components (not shown) of the receiving stage 104 may perform signal processing to convert the reflected beams that are optical signals into digital signals. The signal processing within the receiving stage 104 may include removing parasitic background beams from the reflected beams, and then converting the reflected beams to a plurality of digital signals at a sample rate.

[0047] The controller 108 may control respective operations of the transmitting path 101 and the receiving path 103 of the LIDAR, system by software or hardware or a combination of software and hardware. For examples, the controller 108 controls emitting operations of the transmitting stage 102 (e.g., generate a trigger signal, determine time duration of each beam, synchronize emission of each beam with an identical start time, etc.). With respect to processing the reflected signal within the receiving stage 104, the controller 108 may control a respective sampling rate of the generated digital signals. Furthermore, the controller 108 may control steering operations of the beamsteering stage 106(1).

[0048] By way of non-limiting example, in one possible configuration, the receiving path 103 may include one or more beam-steering device in order to improve accuracy of receiving the reflected beams from the FOV. In some examples, a common beam-steering device may be used in the Tx and Rx paths 101, 103. In other examples, the Tx path 101 and the Rx path 103 may include different beam-steering devices respectively. That is, beam-steering devices in the Tx path 101 and Rx path 103 may be identical or different in accordance with any suitable configurations. In some examples, the beam-steering devices in the Tx path 101 or the Rx path 103 may include non-mechanical beam steering devices, such as digital beam steering devices (DBSDs). In some other examples, the beamsteering devices in the Tx path 101 or the Rx path 103 may be any suitable beam steering devices. [0049] FIG. 2A illustrates an example Tx path 101 of the LIDAR, system 100 which generates beams in more than two fields of view (FOVs), in accordance with certain embodiments. As shown in FIG. 2A, the Tx path 101 includes the laser 1022, an optional optical collimator 202, an optional depolarizer 204, a polarizing beam splitter (PBS) 206, a mirror 208, a beam steering device (e.g., digital beam steering device (DBSD)) 210, and an optional telescope optics 214. The laser 1022 simultaneously emits a plurality of beams. The PBS 206 splits the plurality of beams into a first plurality of beams and a second plurality of beams. In a scenario where polarizations of the plurality of beams generated by the laser 1022 have stable polarizations, a cardinality of the first plurality of beams is identical to that of the second plurality of beams. The term "stable" disclosed herein means that a cardinality of beams with a first polarization (e.g., linear s-polarization) equals to a cardinality of beams with a second polarization (e.g., linear p-polarization). In the example of FIG. 2A, the mirror 208 receives the first plurality of beams from the PBS 206 and then scans the first plurality of beams in a first FOV 210. Because the mirror 208 reflects the first plurality of incident beams without steering the incident beams, the first FOV 210 is a range or an angle around zero degree (i.e., 0° with respect to the x axis), which is also referred to as a central region of a desired FOV of the LIDAR system 100 or a central FOV. As the range of the central FOV is not adjustable, the central FOV is fixed, which is also known as fixed FOV. The desired FOV disclosed herein means a FOV which the LIDAR system 100 is desired or configured to achieve, which is also known as full FOV.

[0050] Regarding the second plurality of beams which are received by the DBSD 210, the DBSD 210 is then controlled (e.g., by the controller 108) to steer the second plurality of incident beams scanning in a second FOV 212. The second FOV 212 is a range that is generated by steering the incident beams scanning between two edges of the desired FOV. The second FOV 212 is referred to as a steered FOV, which may include a plurality of FOV segments in azimuth and/or elevation. In the example of FIG. 2A, the second FOV 212 excludes a range of the first FOV 210.

[0051] As the cardinality of the first plurality of beams scanned in the first FOV 210 equals to the cardinality of the second plurality of beams scanned in the second FOV 212, power of the first plurality of beams is identical to that of the second plurality of beams. Furthermore, the first FOV 210 at the central region is relatively small compared to the second FOV 212; therefore, power density in the first FOV 210 is relatively high compared to the conventional manner which would use a DBSD to steer beams in the desired FOV (e.g., full FOV of the LIDAR, system). Thus, transmission efficiency in the first FOV at the central region is improved significantly, which may also help to increase signal to noise ratio (SNR). Therefore, accuracy of measuring or capturing objects in the central region is boosted as well. Furthermore, a time period for data acquisition in the first FOV 210 may be improved.

[0052] What is more, as the first FOV and the second FOV constitute a hybrid FOV which includes a steered FOV and a fixed FOV, flexibility of the LIDAR system is advanced. Although this example illustrates that the hybrid FOV comprises two types of FOVs (e.g., fixed FOV and steered FOV), it other examples, the hybrid FOV may include one single type FOV (e.g., two steered FOV as shown in FIG. 3C below) or a combination of two central FOVs and one steered FOV (e.g., two fixed FOV and one steered FOV as shown in FIG. 3B below), which will be discussed further below.

[0053] As discussed above, only the laser 1022 and the PBS 206 are needed to generate two set of beams (each having a respective polarization) with an identical cardinality in a scenario where the laser 1022 is a polarized source. As the laser 1022 of the LIDAR system is polarized, the laser 1022 emits beams each with a stable polarization, 50% of the plurality of beams is split to scan objects in the first FOV 210, and the other 50% of the plurality of beams is separated to scan objects in the second FOV 212. However, this is only illustrative and is not intended to be limiting. Percentages of beams used for scanning in the first and second FOVs may be adjusted in accordance with configurations in the scenario where the polarized source is used. For example, 30% of plurality of beams may be used for scanning objects in the first FOV, and 70% of plurality of beams may be used in scanning objects in the second FOV.

[0054] In some examples, the first FOV plus the second FOV equal to the desired FOV of the LIDAR system 100. In other possible configurations, the first FOV may have some portion that overlaps with the second FOV. In that case, the first FOV plus the second FOV is greater than the desired FOV. But the two side edges of the second FOV are identical to those of the desired FOV. That means, maximum directions that the second FOV 212 can reach are the maximum directions that the desired FOV can achieve.

[0055] In some examples, the laser 1022 may include at least one surfaceemitting laser, such as a vertical-cavity surface-emitting laser (VCSEL). Although VCSELs offer stability, reliability, and efficiency, VCSELs generate no fixed or predictable polarizations. Referring back to FIG. 2A in which the at least one surface emitting laser is applied for the laser 1022, in order to improve the transmission efficiency in the first FOV 210, the Tx path 101 may further comprise the depolarizer 204 to enable each beam output from the depolarizer 204 to have a stable polarization. In particular, given the plurality of beams emitted by the laser 1022 include a first plurality of beams each of which has a first polarization and a second plurality of beams each of which has a second polarization, one of the cardinalities of the first plurality and/or the cardinality of the second plurality is changed or adjusted by the depolarizer 204, in order to ensure that the changed cardinality of the first plurality equals to the changed cardinality of the second plurality. As beams input to the PBS 206 have a stable polarization, the PBS 206 then separates the input beams into two set with an identical power, and the mirror 208 will use one set to scan objects in the first FOV 210 and the DBSD 210 will steer the other set to scan objects in the second FOV 212. Thus, the depolarizer 204 may help to equal a cardinality of beams with one polarization to a cardinality of beams with the other polarization. Accordingly, power of the beams with one polarization that are scanned in the first FOV equals to that with the other polarization, which may be beneficial to improve transmission efficiency in the central region of the desired FOV as well.

[0056] In one possible configuration, the Tx path 101 may further include the optional optical collimator 202. The optional optical collimator 202 helps to align the plurality of beams generated by the laser 1022 to be parallel, which may help to improve overall performance of the LIDAR system. [0057] In some alternative examples, the Tx path 101 may incorporate the telescope optics 214 which is connected to the mirror 208. The telescope optics 214 receives the first plurality of beams from the mirror 208 and focuses the first plurality of beams in a third FOV 211. As the first plurality of beams output by the mirror 208 is further concentrated in the third FOV 211, a range or an angle of the third FOV 211 is less than that the first FOV 210, i.e., the third FOV 211 is narrower than the first FOV 210. Therefore, the telescope optics 214 may enable resolution and power density in the central region of the desired FOV to be advanced, which may further improve transmission efficiency in the central region of the desired FOV.

[0058] By way of non-limiting example, in one possible configuration, one or more spreading optics may be added in the Tx path 101 in order to improve divergence of beams which are used for scanning in different respective FOVs. In this regard, reference is now made to FIG.2F, which shows that the Tx path 101 includes a first and second beam spreading optics 232(1), 232(2), in addition to components described in FIG. 2A. The first beam spreading optics 232(1) is connected to the telescope optics 214, and the first plurality of beams output from the telescope optics 214 are spread in a FOV 234 a range of which is greater than the range of the third FOV 211. The second beam spreading optics 232(2) is coupled to the DBSD 210 and spreads the second plurality of beams output from the DBSD 210 in a FOV 236 a range of which is greater than the range of the second FOV 236. In some examples, each of the first and second beam spreading optics may include a lens, a lens array, a diffuser, or another optical element suitable to increase divergence of light beams. By applying the two beam spreading optics within the LIDAR, system, angles of incident beams can be reduced because the reduced angle can be spread by the respective beam spreading optics afterwards. Furthermore, as more beams are spread at edges of FOV with magnification, transmission efficiency at edges of the desired FOV may be significantly increased. In additions, due to reduced angle of incident beams, performance (e.g., great contrast ratio between two polarizations, such as linear s- polarization and linear p-polarization) of the PBS 206 may be also improved. [0059] FIG. 2B shows an alternative example Tx path 101 of the LIDAR, system 100 which separates beams in two or more FOVs, in accordance with alternative embodiments. The configuration of Tx path 101 in FIG. 2B is similar to that of FIG. 2A except that the Tx path 101 of FIG. 2B comprises an additional beam splitter 222 and two optional wedges 224(1), 224(2). The beam splitter 222 may be a 50:50 beam splitter which splits the first plurality of beams to a third and fourth plurality of beams. As a split ratio of the beam splitter 222 is 50:50, each cardinality of the third, fourth plurality of beams includes 50% of the first plurality of beams overall. The third plurality of beams output from the beam splitter 222 are used to scan objects in a third FOV 226(2). The mirror 208 then receives the fourth plurality of beams and reflects the fourth plurality of beams in a fourth FOV 226(1). As the third and fourth plurality of beams are output to scan objects without being steered, each of the third and fourth FOVs 226(1), 226(2) is around zero degree (i.e., at central region of the desired FOV). Each range of the third and fourth FOVs 226(1), 226(2) may be half of that of the first FOV 210. That is, the third FOV 226(2) equals to ¹/2 of the first FOV 210, and the fourth FOV 226(1) equals to ¹/2 of the first FOV 210.

[0060] The reason that each range of the third and fourth FOVs 226(1), 226(2) is half of that of the first FOV 210 is because a focal lens of the optical collimator 202 is adjusted to enable beams output from the depolarizer 204 to have a range that is half of that of the first FOV 210. In some alternative examples, the focal lens of the optical collimator 202 may be altered in order to enable the beams output from the depolarizer 204 to have a range that is identical to that of the first FOV 210. In that case, each of the range of the third and fourth FOV 226(1), 226(2) is same to that of the first FOV 210. In this example, although power of beams in each of the third and fourth FOVs is half of that in the first FOV 210, the transmission efficiency at the central region of the desired FOV may be advanced significantly.

[0061] Although one single beam splitter 222 is illustrated and discussed herein, this is only illustrative and is not intended to be limiting. In other examples, more than one beam splitter 222 may be added between the PBS 206 and the mirror 208. It is also noted that, although the PBS 206 and the mirror 208 in FIG. 2A, the PBS 206, the mirror 208, and the one or more beam splitter 222 in FIG. 2B, are separate components within the Tx path 102, in other possible configurations, the PBS 206 and the mirror 208 may be integrated as one component. The one or more beam splitter 222 may also be embedded within a single piece component in which the PBS 206 and the mirror 208 are included. Such integration of separate components into one single piece may help to reduce the size of the LIDAR, system.

[0062] By incorporating one or more beam splitter 222 between the PBS 206 and the mirror 208 in the Tx path 101, eye safety of the LIDAR system is improved significantly. Furthermore, as the focal lens of the optical collimator 202 can be configured to control angles of beams output from the depolarizer 204, angles of incident beams on the PBS 206 may be reduced. Hardware requirements of the laser may be reduced accordingly.

[0063] In some examples, the Tx path 101 encompasses a first and second wedge 224(1), 224(2). The first wedge 224(2) helps to control angles of the third plurality of beams in the third FOV 226(2). The second wedge 224(1) and the mirror 208 collaborate to deflect the fourth plurality of beams in the fourth FOV 226(1). Incorporating the first and second wedges with the mirror and the beam splitter in the Tx path 101 constitutes an opto-mechanical assembly. The optomechanical assembly may help to control angles of beams in the respective FOV with greater accuracy. Thus, a size of the LIDAR system may be reduced, and addressability to scan a specific object may be simplified.

[0064] In the examples of FIGs. 2A and 2B, the angle of the mirror 208 is 45 degrees with respect to the x axis. Therefore, beams used to scan objects in the first FOV 210 and the fourth FOV 226(1) are at the central region (i.e., 0° with respect to x axis) of the desired FOV. In some examples, if the mirror 208 is placed at other angles (e.g., 30° or 60°) with respect to x axis, the corresponding FOV may not be at the central region of the desired FOV. That is to say, the corresponding FOV is no longer at 0° with respect to the x axis. Reference is now made to FIG.2C, which illustrates an alternative Tx path 101 where a mirror is placed at 60° with respect to the x axis. Components of FIG. 2C are identical to those of FIG. 2A except that a placement angle of the mirror is changed. Accordingly, the angle of the first FOV 210 is altered or rotated to a region at 60° with respect to the x axis. Thus, the angle of the first FOV 210 may be rotated by altering an angle of placing the mirror 208. Because the region of the first FOV 210 is rotated to 60° with respect to the x axis, the DBSD 210 as shown in FIG. 2C is controlled to steer beams in a remaining region of the desired FOV. Therefore, the second FOV 212 in this example covers the remaining region of the desired FOV segments of which are consecutive, rather than the second FOV 212 separated by the first FOV 210 of FIG. 2A as shown FIG. 2A. In other possible configurations, the second FOV 212 may cover the entire desired FOV of the LDIAR system or any FOV that is preconfigured. In this example, adjusting the placement angle of the mirror 208 helps to improve transmission efficiency of any FOV. Furthermore, a time period of acquisition data at the first FOV may be improved significantly.

[0065] FIG. 2D demonstrates an alternative example Tx path 101 of the LIDAR, system 100 in accordance with alternative embodiments. Configuration of FIG. 2D is similar to that of FIG. 2A except that the DBSD 210 is placed at an angle (e.g., -30°) with respect to the x axis. The DBSD 210 is controlled to steer beams in the second FOV 212 to be successive. The second FOV 212 plus the first FOV 210 equals the desired FOV of the LIDAR system. In some other examples, the second FOV 212 may cover other pre-configured FOV. Thus, the angle of the second FOV 212 may be rotated in accordance with the placement angle of the DBSD 210. Comparing FIGs. 2C and 2D with FIG. 2A, angles of the first FOV 210 and the second FOV 212 can be easily changed by altering placement angles of the mirror 208 and the DBSD 210 respectively, which may introduce greater flexibility of the LIDAR system.

[0066] FIG. 2E is another example Tx path 101 of the LIDAR system 100 in accordance with alternative embodiments. The transmitting stage 102 of FIG. 2E is similar to that of FIG. 2A. In the example of FIG. 2E, the DBSD 210 is connected to the mirror 208 to receive the first plurality of beams and steers the first plurality of beams in the second FOV 212. The second plurality of beams produced by the PBS 206 are used for scanning in the first FOV 210, which is at the central region of the desired FOV. It is understood that components of FIG. 2A are same to those of FIG. 2E. The only change is that position of the DBSD is altered from coupling to the PBS 206 as shown in FIG. 2A to connecting to the mirror 208 of FIG. 2E. Therefore, regardless of positions of the DBSD 210, the two different respective FOVs 210 and

212 are achieved readily within the single one LIDAR, system.

[0067] FIG. 3A is another example Tx path 101 of the LIDAR system 100 which generates beams in more than one FOVs in accordance with alternative embodiments. In this example, the mirror is removed from the Tx path 101 compared with the Tx path 101 of FIG. 2A. Thus, the first plurality of beams are output from the PBS 206 and scan in a FOV 302 which includes a region around 90° with respect to the x axis. The DBSD 210 of the Tx path 101 in FIG. 3A is controlled to steer the second plurality of beams in a FOV 304, which may be the desired FOV. In this example, the FOV 304 may cover the entire range of the desired FOV. Accordingly, the FOV 302 can be considered to enlarge a FOV of the LIDAR system overall because objects in the FOV 302 can be captured in addition to objects captured from the desired FOV 304 (e.g., full FOV). Using the PBS 206 to separate beams into two sets enables an overall FOV of the LIDAR system to be enlarged without using two separate LIDAR systems or two lasers. Rather than using two lasers or two LIDAR systems, the implementation of one single laser within one single LIDAR system may be beneficial to reduce hardware cost to achieve the enlarged FOV, especially in autonomous driving applications.

[0068] FIG. 3B shows an alternative example Tx path 101 of the LIDAR system 100 which separates beams in two or more FOVs that constitute a hybrid FOV, in accordance with alternative embodiments. Components in FIG.3B are similar to those of in FIG. 3A except that the PBS 206 of FIG. 3A is replaced with an optical glass X-cube 312, in the Tx path 101. The optical glass X-cube 312 splits the plurality of beams emitted by the laser 1022 into three sets. A first set of beams output from the optical glass X-cube 312 are input to the DBSD 210, and the DBSD 210 scans the first set of beams in a full FOV 304. A second set of beams generated from the optical glass X-cube 312 scan a FOV 314 which is around 90° with respect to the x axis, and a third set of beams scan a FOV 316 which is around -90° with respect to the x axis. Thus, the hybrid FOV generated by the LIDAR system includes two central or fixed FOVs 314 and one steered FOV 304, which helps to enlarge a range of an overall FOV for the LIDAR system 100 significantly. Thus, incorporating the optical glass X-cube 312 into the Tx path of the LIDAR, system may help to save hardware costs and help to avoid employing three different LIDAR systems to achieve three different FOVs.

[0069] It is appreciated that FOVs as shown in each of FIGs. 2-3B include a first FOV which is fixed and whose range is relatively smaller and a second FOV in which beams are steered. The second FOV is a relatively larger than the first FOV because the beams in the second FOV can be steered. In some examples, the second FOV excludes the first FOV. In alternative examples, the second FOV may cover the desired FOV or any suitable configuration of the LDIAR system. Because the beams in the smaller first FOV has power that is identical to those in the larger second FOV. The transmission efficiency in the first FOV is improved significantly without causing too many hardware changes in the LIDAR system.

[0070] Referring to FIG. 3C, an alternative example Tx path 101 of the LIDAR system 100 is demonstrated to separate beams in more than one FOVs, in accordance with alternative embodiments. In the example of FIG. 3C, two DBSDs 210, 322 are connected with the PBS 206 such that each DBSD can steer a set of beams in a respective FOV. In particular, the DBSD 322 steers the first plurality of beams split by the PBS 206 in one FOV 324, and the DBSD 210 steers the second plurality of beams output by the PBS 206 in another FOV 304. As the DBSD 322 has abilities to steer the first plurality of beams between edges of the FOV 324 back and forth, a wider FOV is formed as the FOV 324, rather than a fixed FOV around the central region of the desired FOV. Connecting another DBSD (e.g., DBSD 322) with the PBS 206 enables two respective FOVs to be wider. In particular, the range of the FOV 324 is improved significantly. Furthermore, as the PBS splits beams into two directions, the beams scanned in the FOV 324 are directed to the y axis while the central region of the FOV 304 is along the x axis. The hybrid FOV including two different FOVs generated by the LIDAR system may help to avoid using two LIDAR systems in some applications where different FOVs are required.

[0071] Regarding the Rx path 103 of the LIDAR systems 100, FIG. 4 illustrates an example Rx path 103 which can be used to receive reflected beams that are output from the Tx path 101 as shown in FIGs. 2A-3C. The Rx path 103 encompasses a first sub-Rx path 402(1) and a second sub-Rx path 402(2) (generically referred to as sub-Rx path 402). Each sub-Rx path 402 includes a receiver 1042 (e.g., the receivers 1042(1) and 1042(2) are generically referred to as receiver 1042) and an optional optical device 404 (e.g., the optical devices 404(1) and 404(2) are generically referred to as optical device 404). The optical device 404 may be an optical collimator to collimate beams backscattered from a FOV and send the collimated beams to the receiver 1042. The receiver 1042 then calculates a time period of data acquisition and capture objects in the FOV. In the example of FIG. 4, each of the first sub-Rx path 402(1) and the second sub-Rx path 402(2) is controllable to receive beams reflected from different kinds of FOVs, such as including a fixed FOV 210 or 211 at the central area of the desired FOV as shown in FIG. 2A, the second FOV 212 which excludes the first FOV 210 or 211 of FIG. 2A, and the FOV 304 and 324 of FIG. 3C.

[0072] It is noted that, although some sub-Rx path may be controlled to receive beams from an entire full FOV, in other examples, some other sub-Rx path may correspond to a respective FOV generated from the Tx paths 101 of FIGs. 2A- 3C.

[0073] For example, in order to ensure beams generated from the Tx path 101 of FIG. 2A to be received at the Rx path 103 with greater accuracy, the first sub-Rx path 402(1) may receive beams reflected from the desired FOV (e.g., the full FOV includes the first and second FOV 210, 212) of FIG. 2A to detect objects within the desired FOV. The second sub-Rx path 402(2) may be designated to receive beams reflected from the first FOV 210. In this example, the first sub-Rx path 402(1) is designed to detect beams in the desired FOV (e.g., full FOV) of FIG. 2A, rather than the second FOV 212 which excludes the first FOV 210. In that case, beams reflected from the first FOV 210 are received twice by the two sub-Rx paths. Therefore, including the two sub-Rx paths into the Rx path may help to increase accuracy of averaging and SNR in the first FOV 210. This is only illustrative and not intended to be limiting. In other examples, each sub-Rx path may be used to receive beams reflected from a corresponding FOV generated from the Tx path 101 as shown in FIG. 2A. [0074] With respect to beams generated in different respective FOVs (each is along a respective axis) in Tx paths as shown in FIGs. 3A-3C, the first and second sub-Rx path 402(1) and 402(2) in the example of FIG. 4 may receive the first and second plurality of beams in the corresponding FOVs respectively.

[0075] Taking FIG. 30 for example, to receive beams reflected in the Tx path of FIG. 30, the first and second sub-Rx path 402(1), 402(2) are controlled to ensure beams reflected from the FOV 324 and beams reflected from the FOV 304 to be received with greater accuracy. In this scenario, the first sub-Rx path 402(1) receives beams reflected from the FOV 324, and the second sub-Rx path 402(2) captures beams reflected from the FOV 304. As the hardware cost at the Tx path is reduced significantly, the two sub-Rx paths help to keep overall hardware costs of the LIDAR system low without compromising any accuracy or performance. In some examples, the TX path 103 may include one or more beam-steering devices, such as DBSDs 406(1) and 406(2) (generically referred to DBSD 406), on a corresponding sub-Rx path. The DBSD 406 may help to receive beams reflected back from the FOVs with greater accuracy. In some examples, the TX path 101 and the Rx path 103 may use one or more common DBSD. In particular, for portions in the Tx path 101 and portions in the Rx path 103 correspond to an identical FOV, a common DBSD may be used to steer and receive beams within the identical FOV. For example, reference is made with respect to FIGs. 3C and 4, the DBSD 322 of FIG. 3C for steering beams in the FOV 324 may also be employed as the DBSD 406(1) in the first sub-Rx path 402(1) to receive beams backscattered from the FOV 324. Likewise, the DBSD 304 of FIG. 3C for steering beams in the FOV 304 may be utilized as the DBSD 406(2) in the second sub-Rx path 402(2) to receive beams backscattered from the FOV 304. By using common DBSDs, the hardware cost of the LIDAR system may be reduced.

[0076] Similarly, with respect to beams scanned in the first FOV 302 and in the second FOV 304 as shown in FIG. 3A, the first sub-Rx path 402(1) receives beams reflected from the first FOV 302, and the second sub-Rx path 402(2) detects beams reflected from the FOV 304. As the first FOV 302 and the FOV 304 are two different FOVs where beams are scanned, the two sub-Rx paths 402 help to ensure the beams scanned into the two different FOVs to be received without any loss. Therefore, efficiency of the LIDAR, system 100 may be improved significantly.

[0077] In an example of receiving beams from three FOVs in FIG. 3B, the Rx path 103 may include three sub-Rx paths each corresponds beams in a respective FOVs 314, 316, and 304. Making minimum changes in the Rx path 103 may help to enable multiple FOVs to be produced within a single LIDAR system. Accordingly, the hardware cost of the LIDAR system is reduced significantly.

[0078] It should be understood that although optical collimators discussed above are utilized to collimate received beams and to generate beams in parallel, in some other configurations, other optical collimators may be disposed at suitable locations in the configurations discussed in FIG. 1-4 to collimate received beams when necessary. In some examples, the optical collimator may include an optical lens.

[0079] Although the present disclosure describes methods and processes with steps in a certain order, one or more steps of the methods and processes may be omitted or altered as appropriate. One or more steps may take place in an order other than that in which they are described, as appropriate.

[0080] Although the present disclosure is described, at least in part, in terms of methods, a person of ordinary skill in the art will understand that the present disclosure is also directed to the various components for performing at least some of the aspects and features of the described methods, be it by way of hardware components, software or any combination of the two. Accordingly, certain technical solutions of the present disclosure, especially in relation to the controller 108 and/or the transmitting stage 102 and/or the receiving stage 104, may be embodied in the form of a software product. A suitable software product may be stored in a pre-recorded storage device or other similar non-volatile or non- transitory computer readable medium, for example. The software product includes instructions tangibly stored thereon that enable a processing device (e.g., a microprocessor) to execute examples of the methods disclosed herein.

[0081] The present disclosure may be embodied in other specific forms without departing from the subject matter of the claims. The described example embodiments are to be considered in all respects as being only illustrative and not restrictive. Selected features from one or more of the above-described embodiments may be combined to create alternative embodiments not explicitly described, features suitable for such combinations being understood within the scope of this disclosure.

[0082] All values and sub-ranges within disclosed ranges are also disclosed. Also, although the systems, devices and processes disclosed and shown herein may comprise a specific number of elements/components, the systems, devices and assemblies could be modified to include additional or fewer of such elements/components. For example, although any of the elements/components disclosed may be referenced as being singular, the embodiments disclosed herein could be modified to include a plurality of such elements/components. The subject matter described herein intends to cover and embrace all suitable changes in technology.

Claims

1. An apparatus for use in a light detection and ranging (LIDAR.) system, the apparatus comprising a transmitting path, the transmitting path comprising: a laser configured to emit a plurality of beams; a polarizing beam splitter (PBS) configured to split the plurality of beams into a first plurality of beams each of which has a first polarization and a second plurality of beams each of which has a second polarization and to generate the second plurality of beams in a second field of view (FOV); and a beam-steering device configured to receive the first plurality of beams and to steer the first plurality of beams in a first FOV.

2. The apparatus of claim 1, wherein the first FOV plus the second FOV equals to a desired FOV of the LIDAR system.

3. The apparatus of claim 1 or 2, further comprising: an optical device configured to receive the second plurality of beams from the PBS and to steer the second plurality of beams in the second FOV.

4. The apparatus of any one of claims 1 to 3, further comprising: a depolarizer configured to receive the plurality of beams, to change polarizations of the plurality of beams, and to output the first plurality of beams each with the first polarization and the second plurality of beams each of the second polarization, wherein a cardinality of the first plurality equals to that of the second plurality.

5. The apparatus of any one of claims 1 to 4, wherein further comprising: an optical collimator configured to receive the plurality of beams and to generate a plurality of collimated beams.

6. The apparatus of claim 3, wherein the optical device includes a mirror.

7. The apparatus of claim 6, wherein the mirror is placed 45° with respect to x axis that is parallel to a central area of a desired FOV, and the second FOV is at a central region of a desired FOV of the LIDAR, system.

8. The apparatus of any one of claims 1 to 3, wherein the apparatus further comprises: telescope optics configured to receive the second plurality of beams and to focus the second plurality of beams in a third FOV, wherein the third FOV is narrower than the second FOV.

9. The apparatus of claim 3, wherein the apparatus further comprises: a beam splitter configured to receive the second plurality of beams from the

PBS and to split the second plurality of beams into a third plurality of beams and a fourth plurality of beams; the optical device configured to receive the third plurality of beams and to generate the third plurality of beams in a third FOV; and the beam splitter further configured to generate the fourth plurality of beams in a fourth FOV.

10. The apparatus of claim 9, wherein each of the third FOV and the fourth FOV is half of the second FOV.

11. The apparatus of claim 9, wherein the third FOV is equal to the fourth FOV, which is identical to the second FOV.

12. The apparatus of claim 9, wherein the apparatus further comprises: a first wedge configured to receive the third plurality of beams from the optical device and to further control angles of the third plurality of beams in the third FOV; and a second wedge configured to receive the fourth plurality of beams from the beam splitter and to further control angles of the fourth plurality of beams in the fourth FOV.

13. The apparatus of claim 3, wherein a placement angle of the optical device is controllable to alter the second FOV.

14. The apparatus of any one of claims 1 to 13, wherein a placement angle of the beam-steering device is controllable to alter the first FOV.

15. The apparatus of any one of claims 1 to 14, wherein the apparatus further comprises: first beam spreading optics configured to receive the first plurality of beams in the first FOV and to spread the first plurality of beams in a FOV that is greater than the first FOV; and second beam spreading optics configured to receive the second plurality of beams in the second FOV and to spread the second plurality of beams in a FOV that is greater than the second FOV.

16. The apparatus of any one of claims 1 to 15, wherein the apparatus further comprises a first receiving path including a first receiver configured to receive the first plurality of beams in the first FOV and the second in the second FOV; and a second receiving path including a second receiver configured to receive the second plurality of beams in the second FOV.

17. The apparatus of claim 3, wherein the optical device includes another beam-steering device.

18. The apparatus of any one of claims 1 to 3, wherein the first FOV and the second FOV constitute a hybrid FOV for the LIDAR, system.

19. An apparatus for use in a light detection and ranging (LIDAR) system, the apparatus comprising: a laser configured to emit a plurality of beams; a first optical device configured to split the plurality of beams into a first, second, and third plurality of beams and to generate the first plurality of beams in a first FOV and the second plurality of beams in a second FOV, wherein a range of the first FOV is identical to that of the second FOV; and a beam-steering device configured to receive the third plurality of beams and to steer the third plurality of beams in a third FOV.

20. The apparatus of claim 19, wherein the first optical device includes an optical glass X-cube.

21. The apparatus of claim 19 or 20, further comprising: an optical collimator configured to receive the plurality of beams and to generate a plurality of collimated beams.

22. The apparatus of any one of claims 19 to 21, further comprising: a depolarizer configured to receive the plurality of beams to change polarizations of the plurality of beams, and to output the first plurality of beams each with a second polarization, the second plurality of beams each with the second polarization, and the third plurality of beams each with a first polarization.