Data refinement in optical systems

Abstract

Data refinement in optical systems Operation of the LIDAR system includes transmitting a system output signal from the LIDAR system such that a sample area is illuminated by the system output signal. During illumination of the sample area, the system output signal includes one check data period and multiple target data periods. The frequency of the system output signal changes at different rates during the target data periods. Light returning to the LIDAR system from the system output signal is combined with light from a reference signal to generate a pulsating signal that pulsates at a pulsating frequency. The reference signal includes light that does not exit the LIDAR system. A comparative pulsating frequency is calculated. The comparative pulsating frequency approximates the value of the pulsating frequency of the pulsating signal during the check data periods. The comparative pulsating frequency is calculated from the pulsating frequency of the pulsating signal during the target data periods.

Description

Related Applications

[0001] This application is a continuation of U.S. Patent Application No. 18 / 106,995, filed February 7, 2023, entitled "Data Refinement in Optical Systems," and is incorporated herein in its entirety.

[0002] The present invention relates to imaging systems, and more particularly to data refinement in imaging systems.

[0003] The LIDAR system outputs a system output signal that is reflected by an object located outside the LIDAR system, and the reflected light returns to the LIDAR system as a system return signal. The LIDAR system includes electronics that use the system return signal to measure LIDAR data (radial velocity and / or distance between the LIDAR system and the object) of a sample area illuminated by the system output signal.

[0004] For a LIDAR system to generate an image of a scene, the system output signal is scanned across the scene. During the scan, LIDAR data is generated for multiple different sample areas within the scene. To generate LIDAR data for a sample area, each sample area is illuminated for a regional period. However, the scanning of the system output signal continues for the regional period. As a result, the system output signal can illuminate one object at the beginning of the regional period and then move to illuminate another object before the end of the regional period. Changing the illuminated object within the regional period causes errors in the LIDAR data. Therefore, there is a need for a LIDAR system that can provide more reliable LIDAR data. Overview

[0005] Operation of the LIDAR system includes transmitting a system output signal from the LIDAR system such that a sample area is illuminated by the system output signal. During illumination of the sample area, the system output signal includes one check data period and multiple target data periods. The frequency of the system output signal changes at different rates during the target data periods. Light returning to the LIDAR system from the system output signal is combined with light from a reference signal to generate a pulsating signal that pulsates at a pulsating frequency. The reference signal includes light that does not exit the LIDAR system. A comparative pulsating frequency is calculated. The comparative pulsating frequency approximates the value of the pulsating frequency of the pulsating signal during the check data periods. The comparative pulsating frequency is calculated from the pulsating frequency of the pulsating signal during the target data periods.

[0006] The LIDAR system is configured to output a system output signal, whereby the sample area is illuminated by the system output signal. During illumination of the sample area, the system output signal includes one check data period and multiple target data periods. The frequency of the system output signal changes at different rates during the target data periods. The LIDAR system includes an optical combiner that combines light returning to the LIDAR system from the system output signal with light from a reference signal to generate a pulsating signal that pulsates at a pulsating frequency. The reference signal includes light that is not emitted from the LIDAR system. The system also includes electronics configured to calculate a comparative pulsating frequency that approximates the value of the pulsating frequency of the pulsating signal during the check data periods. The comparative pulsating frequency is calculated from the pulsating frequency of the pulsating signal during the target data periods. [Brief explanation of the drawings]

[0007] FIG. 1A is a schematic top view of a LIDAR system including or consisting of a LIDAR chip that outputs a LIDAR output signal and receives a LIDAR input signal on a common waveguide.

[0008] FIG. 1B is a schematic top view of a LIDAR system including or consisting of a LIDAR chip that outputs a LIDAR output signal and receives a LIDAR input signal on a different waveguide.

[0009] FIG. 1C is a schematic top view of another embodiment of a LIDAR system that includes or consists of a LIDAR chip that outputs a LIDAR output signal and receives multiple LIDAR input signals on different waveguides.

[0010] FIG. 2 is a top view of an example of a LIDAR adapter suitable for use with the LIDAR chip of FIG. 1B.

[0011] FIG. 3 is a top view of an example LIDAR adapter suitable for use with the LIDAR chip of FIG. 1C.

[0012] FIG. 4 is a top view of an example of a LIDAR system including the LIDAR chip of FIG. 1A and the LIDAR adapter of FIG. 2 on a common support.

[0013] FIG. 5A illustrates an example of a processing unit suitable for use with a LIDAR system.

[0014] FIG. 5B shows a schematic of electronics suitable for use with a processing unit constructed according to FIG. 5A.

[0015] FIG. 5C is a graph of frequency versus time of the system output signal.

[0016] FIG. 5D illustrates edge effects as a source of error in LIDAR data.

[0017] Figure 6 shows a flow diagram of the LIDAR data refinement process.

[0018] Figure 7 shows a cross-sectional view of a portion of a LIDAR chip containing a waveguide on a silicon-on-insulator platform.

[0019] The LIDAR system outputs a system output signal. The frequency of the system output signal varies over a series of repeating cycles. Each cycle includes one check data period and multiple target data periods. The optical combiner combines light returning from the system output signal to the LIDAR system with light from the reference signal to generate a pulsating signal that pulsates at the pulsating frequency. The reference signal includes light that is not emitted from the LIDAR system.

[0020] The electronics can use the pulsatile frequency of the pulsatile signal during a plurality of different target data periods to calculate candidate LIDAR data for a sample area illuminated by the system output signal during a target cycle, the candidate LIDAR data indicating a potential radial velocity and / or a potential distance between the LIDAR system and an object external to the LIDAR system.

[0021] The electronics may also use the pulse frequencies of the pulse signal during a plurality of different target data periods to calculate a comparative pulse frequency that approximates the value of the pulse frequency of the pulse signal during a check data period in the target cycle.

[0022] The comparative pulsating frequency can be calculated so that if the system output signal is incident on the same surface during the target data period and the check data period, the value of the comparative pulsating frequency matches or substantially matches the pulsating frequency during the check data period. However, if the system output signal is not incident on the same surface during the target data period and the check data period, the comparative pulsating frequency and the pulsating frequency during the check data period do not match. For example, if the candidate LIDAR data is constant or substantially constant during the target data period and the check data period, the comparative pulsating frequency and the pulsating frequency during the check data period can match or substantially match. Consistency of the candidate LIDAR data during the target data period and the check data period indicates that the line-of-sight velocity and / or distance between the LIDAR system and the object were constant during the target data period and the check data period. Consequently, constant candidate LIDAR data indicates that the system output signal remained incident on the same surface object during at least the target data period. Therefore, a match or substantial match between the comparative pulsating frequency and the pulsating frequency during the check data period indicates that the system output signal remained incident on the same surface object during at least the target data period.

[0023] By comparing the comparison beat frequency value with the beat frequency value during the check data period, it can be determined whether the system output signal remained incident on the same surface of the object during the target data period. If the comparison indicates that the system output signal did not remain incident on the same surface during the target data period, the LIDAR data for the sample area can be classified as unavailable. On the other hand, if the comparison indicates that the system output signal remained incident on the same surface during the target data period, the candidate LIDAR data for the sample area can be classified as valid. As a result, the LIDAR data for the sample area can be set equal to the candidate LIDAR data for the sample area. Therefore, the LIDAR data for the sample area where the system output signal changes surface can be removed from the LIDAR data for collecting the sample area within the system's field of view. As a result, the LIDAR data for the sample area within the system's field of view can be processed with reduced interference due to edge effect errors.

[0024] The above-described LIDAR data refinement method has also been demonstrated to reduce other errors that occur during the generation of LIDAR data for a sample area within the system's field of view. Outliers occur when LIDAR data for a sample area does not match LIDAR data for surrounding sample areas. Outliers do not necessarily occur at transitions between surfaces; they can also occur in the center of a surface. As a result, outliers can be LIDAR data from a surface that does not match LIDAR data for other locations on that surface. Removing candidate LIDAR data that do not remain constant or substantially constant during illumination of the sample area has been demonstrated to reduce the presence of outliers. Extracting these candidate LIDAR data values ​​from the final LIDAR data values ​​within the field of view also reduces aliasing.

[0025] 1A is a schematic top view of a LIDAR chip that can function as a LIDAR system or can be incorporated into a LIDAR system that includes components in addition to the LIDAR chip. The LIDAR chip can include a photonic integrated circuit (PIC) or can be an integrated photonic integrated circuit chip. The LIDAR chip includes a light source 4 that outputs a preliminary emitted LIDAR signal. Suitable light sources 4 include, but are not limited to, semiconductor lasers such as external cavity lasers (ECLs), distributed feedback lasers (DFBs), discrete mode (DM) lasers, and distributed Bragg reflector lasers (DBRs).

[0026] The LIDAR chip includes a utility waveguide 12 that receives the outgoing LIDAR signal from the light source 4. The utility waveguide 12 terminates at a facet 14 and transmits the outgoing LIDAR signal to the facet 14. The facet 14 can be positioned such that the outgoing LIDAR signal passing through the facet 14 exits the LIDAR chip and functions as the LIDAR output signal. For example, by positioning the facet 14 at the end of the chip, the outgoing LIDAR signal passing through the facet 14 exits the chip and functions as the LIDAR output signal. In some cases, a portion of the LIDAR output signal exiting the LIDAR chip can also be considered a system output signal. For example, if the output of the LIDAR output signal from the LIDAR chip is also the output of the LIDAR output signal from the LIDAR system, the LIDAR output signal can also be considered a system output signal.

[0027] The LIDAR output signal travels away from the LIDAR system through free space in the atmosphere where the LIDAR system is located. The LIDAR output signal may be reflected by one or more objects along the path of the LIDAR output signal. When the LIDAR output signal is reflected, at least a portion of the reflected light returns to the LIDAR chip as the LIDAR input signal. In some cases, the LIDAR input signal may also be considered a system return signal. For example, if the exit of the LIDAR output signal from the LIDAR chip is also the exit of the LIDAR output signal from the LIDAR system, the LIDAR input signal may also be considered a system return signal.

[0028] A LIDAR input signal can be incident on utility waveguide 12 through facet 14. A portion of the LIDAR input signal incident on utility waveguide 12 serves as the incident LIDAR signal. Utility waveguide 12 transmits the incident LIDAR signal to splitter 16. Splitter 16 transmits a portion of the outgoing LIDAR signal from utility waveguide 12 to comparison waveguide 18 as a comparison signal. Comparison waveguide 18 transmits the comparison signal to processing unit 22 for further processing. While FIG. 1A shows a directional coupler operating as splitter 16, other signal tap components can also be used as splitter 16. Suitable splitters 16 include, but are not limited to, directional couplers, optical couplers, Y-junctions, tapered couplers, and multi-mode interference (MMI) devices.

[0029] The utility waveguide 12 also transmits the outgoing LIDAR signal to a splitter 16. The splitter 16 transmits a portion of the outgoing LIDAR signal from the utility waveguide 12 as a reference signal to a reference waveguide 20. The reference waveguide 20 transmits the reference signal to a processing unit 22 for further processing.

[0030] The fraction of light redirected by the splitter 16 from the utility waveguide 12 can be fixed or substantially fixed. For example, the splitter 16 can be configured so that the power of the reference signal redirected to the reference waveguide 20 is an outgoing fraction of the power of the outgoing LIDAR signal, or so that the power of the comparison signal redirected to the comparison waveguide 18 is an incoming fraction of the power of the incoming LIDAR signal. For many splitters 16, such as directional couplers and multimode interferometers (MMIs), the outgoing fraction is equal to or substantially equal to the incoming fraction. In some cases, the outgoing fraction is greater than 30%, 40%, or 49% and / or less than 51%, 60%, or 70%; and / or the incoming fraction is greater than 30%, 40%, or 49% and / or less than 51%, 60%, or 70%. Splitters 16, such as multimode interferometers (MMIs), typically have an outgoing fraction to an incoming fraction of 50% or approximately 50%. However, multimode interferometers (MMIs) are easier to fabricate than other alternatives in platforms such as silicon-on-insulator (SOI) platforms. In one example, splitter 16 is a multimode interferometer (MMI) with a 50% or substantially 50% outgoing / incoming fraction. As described in more detail below, processing unit 22 combines the comparison signal and the reference signal to form a composite signal conveying LIDAR data for a sample area within the field of view. Thus, processing the composite signal can extract LIDAR data for the sample area (e.g., line-of-sight velocity and / or distance between the LIDAR system and an object external to the LIDAR system).

[0031] The LIDAR chip may include a control branch for controlling the operation of the light source 4. The control branch includes a splitter 26 that transmits a portion of the outgoing LIDAR signal from the utility waveguide 12 to a control waveguide 28. The combined portion of the outgoing LIDAR signal serves as a tap signal. While FIG. 1A shows a directional coupler acting as the splitter 26, other signal tap components may also be used as the splitter 26. Suitable splitters 26 include, but are not limited to, directional couplers, optical couplers, Y-junctions, tapered couplers, and multi-mode interference (MMI) devices.

[0032] The control waveguide 28 transmits the tap signal to a controller 30. The controller may be in electrical communication with electronics 32. All or a portion of the controller may be included in the electronics 32. In operation, the electronics may use the output from the controller 30 in a control loop configured to control process variables of one, two, or three loop control optical signals selected from the group consisting of the tap signal, the system output signal, and the outgoing LIDAR signal. Examples of suitable process variables include the frequency of the loop control optical signal and / or the phase of the loop control optical signal.

[0033] LIDAR systems can be modified so that the incoming and outgoing LIDAR signals are transmitted through different waveguides. For example, FIG. 1B illustrates a top view of the LIDAR chip of FIG. 1A modified so that the incoming and outgoing LIDAR signals are transmitted through different waveguides. The outgoing LIDAR signal exits the LIDAR chip through facet 14 and serves as the LIDAR output signal. When light from the LIDAR output signal is reflected by an object external to the LIDAR system, at least a portion of the reflected light returns to the LIDAR chip as the first LIDAR input signal. The first LIDAR input signal enters comparison waveguide 18 through facet 35 and serves as the comparison signal. Comparison waveguide 18 transmits the comparison signal to processing unit 22 for further processing. As described in FIG. 1A, reference waveguide 20 transmits a reference signal to processing unit 22 for further processing. As will be explained in more detail below, processing unit 22 combines the comparison signal and the reference signal to generate a composite signal that conveys LIDAR data for the sample area within the field of view.

[0034] The LIDAR chip can be modified to receive multiple LIDAR input signals. For example, FIG. 1C illustrates the LIDAR chip of FIG. 1B modified to receive two LIDAR input signals. A splitter 40 is configured to place a portion of the reference signal transmitted by the reference waveguide 20 in a first reference waveguide 42 and another portion of the reference signal in a second reference waveguide 44. Thus, the first reference waveguide 42 transmits the first reference signal, and the second reference waveguide 44 transmits the second reference signal. The first reference waveguide 42 transmits the first reference signal to a first processing section 46, and the second reference waveguide 44 transmits the second reference signal to a second processing section 48. Examples of suitable splitters 40 include, but are not limited to, a Y-junction, an optical coupler, and a multimode interference coupler (MMI).

[0035] The outgoing LIDAR signal exits the LIDAR chip through facet 14 and serves as the LIDAR output signal. When light from the LIDAR output signal is reflected by one or more objects external to the LIDAR system, at least a portion of the reflected light returns to the LIDAR chip as a first LIDAR input signal. The first LIDAR input signal enters comparison waveguide 18 through facet 35 and serves as a first comparison signal. Comparison waveguide 18 transmits the first comparison signal to first processing unit 46 for further processing.

[0036] Additionally, when light from the LIDAR output signal is reflected by one or more objects external to the LIDAR system, at least a portion of the reflected signal returns to the LIDAR chip as a second LIDAR input signal. The second LIDAR input signal enters the second comparison waveguide 50 through facet 52 and serves as a second comparison signal transmitted by the second comparison waveguide 50. The second comparison waveguide 50 transmits the second comparison signal to the second processing unit 48 for further processing.

[0037] Although light source 4 is shown as being located on the LIDAR chip, light source 4 can also be located off the LIDAR chip. For example, utility waveguide 12 can terminate at a second facet that allows an outgoing LIDAR signal from light source 4 located off the LIDAR chip to enter utility waveguide 12.

[0038] 1B or 1C is used in combination with a LIDAR adapter. In some cases, the LIDAR adapter can be physically and optically positioned between the LIDAR chip and one or more reflective objects and / or the field of view, such that the optical paths along which the first LIDAR input signal and / or the LIDAR output signal travel from the LIDAR chip to the field of view pass through the LIDAR adapter. Additionally, the LIDAR adapter can be configured to operate based on the first LIDAR input signal and the LIDAR output signal, such that the first LIDAR input signal and the LIDAR output signal travel on different optical paths between the LIDAR adapter and the LIDAR chip but travel on the same optical path between the LIDAR adapter and the reflective objects in the field of view.

[0039] An example of a LIDAR adapter suitable for the LIDAR chip of FIG. 1B is shown in FIG. 2. The LIDAR adapter includes multiple components disposed on a base. For example, the LIDAR adapter includes a circulator 100 disposed on a base 102. The illustrated optical circulator 100 includes three ports, configured so that light entering one port exits the next port. For example, the illustrated optical circulator includes a first port 104, a second port 106, and a third port 108. The LIDAR output signal enters the first port 104 from the utility waveguide 12 of the LIDAR chip and exits the second port 106.

[0040] The LIDAR adapter can be configured such that the output of the LIDAR output signal from the second port 106 also functions as the output of the LIDAR output signal from the LIDAR adapter, and thus from the LIDAR system. As a result, the LIDAR output signal can be output from the LIDAR adapter to travel toward a sample area within the field of view. Therefore, in some cases, a portion of the LIDAR output signal output from the LIDAR adapter can also be considered a system output signal. For example, if the output of the LIDAR output signal from the LIDAR adapter is also the output of the LIDAR output signal from the LIDAR system, the LIDAR output signal can also be considered a system output signal.

[0041] The LIDAR output signal output from the LIDAR adapter includes, consists of, or consists essentially of light from the LIDAR output signal received from the LIDAR chip. Thus, the LIDAR output signal output from the LIDAR adapter may be the same as or substantially the same as the LIDAR output signal received from the LIDAR chip. However, there may be differences between the LIDAR output signal output from the LIDAR adapter and the LIDAR output signal received from the LIDAR chip. For example, the LIDAR output signal may experience optical loss as it passes through the LIDAR adapter, and / or the LIDAR adapter may optionally include an amplifier configured to amplify the LIDAR output signal as it passes through the LIDAR adapter.

[0042] When one or more objects within the sample volume reflect the LIDAR output signal, at least a portion of the reflected light returns to the circulator 100 as a system return signal. The system return signal enters the circulator 100 through a second port 106. Figure 2 shows the LIDAR output signal and the system return signal traveling along the same optical path between the LIDAR adapter and the sample volume.

[0043] The system return signal exits the circulator 100 through a third port 108 and is directed to a comparison waveguide 18 on the LIDAR chip. Thus, all or a portion of the system return signal can function as the first LIDAR input signal, which can include or consist of light from the system return signal. Thus, the LIDAR output signal and the first LIDAR input signal travel along different optical paths between the LIDAR adapter and the LIDAR chip.

[0044] As is apparent from Figure 2, the LIDAR adapter can include optical components in addition to the circulator 100. For example, the LIDAR adapter can include components for directing and controlling the optical paths of the LIDAR output signal and the system return signal. As an example, the adapter of Figure 2 includes an optional amplifier 110 positioned to receive and amplify the LIDAR output signal before it enters the circulator 100. The amplifier 110 is operated by the electronics 32, allowing the electronics 32 to control the power of the LIDAR output signal.

[0045] FIG. 2 also illustrates a LIDAR adapter including an optional first lens 112 and an optional second lens 114. The first lens 112 can be configured to couple the LIDAR output signal to a desired location. In some cases, the first lens 112 is configured to focus or collimate the LIDAR output signal to a desired location. In one example, if the LIDAR adapter does not include an amplifier 110, the first lens 112 can be configured to couple the LIDAR output signal to the first port 104. As another example, if the LIDAR adapter includes an amplifier 110, the first lens 112 can be configured to couple the LIDAR output signal on the input port to the amplifier 110. The second lens 114 can be configured to couple the LIDAR output signal to a desired location. In some cases, the second lens 114 is configured to focus or collimate the LIDAR output signal to a desired location. For example, the second lens 114 can be configured to couple the LIDAR output signal onto facet 35 of the comparison waveguide 18.

[0046] The LIDAR adapter may also include one or more redirecting elements, such as mirrors. Figure 2 shows a LIDAR adapter including a mirror as a redirecting element 116 that redirects the system return signal from the circulator 100 to the facet 20 of the comparison waveguide 18.

[0047] The LIDAR chip includes one or more waveguides that restrict the optical path of one or more optical signals. While the LIDAR adapter can include waveguides, the optical paths along which the system return signals and LIDAR output signals travel between components on the LIDAR adapter and / or between the LIDAR chip and components on the LIDAR adapter can be free space. For example, the system return signals and / or LIDAR output signals can travel through the air in which the LIDAR chip, LIDAR adapter, and / or base 102 are located as they travel between different components on the LIDAR adapter and / or between components on the LIDAR adapter and the LIDAR chip. As a result, optical components such as lenses and redirectors can be used to control the characteristics of the optical paths along which the system return signals and LIDAR output signals travel on, to, and from the LIDAR adapter.

[0048] Suitable bases 102 for LIDAR adapters include, but are not limited to, substrates, platforms, and plates. Suitable substrates include, but are not limited to, glass, silicon, and ceramic. The components may be discrete components attached to the substrate. Suitable techniques for attaching discrete components to the base 102 include, but are not limited to, epoxy, solder, and mechanical clamps. In one example, one or more components are integrated components and the remaining components are discrete components. In another example, the LIDAR adapter includes one or more integrated amplifiers and the remaining components are discrete components.

[0049] LIDAR systems can be configured to compensate for polarization. Light from a laser source is typically linearly polarized, and therefore the LIDAR output signal is also typically linearly polarized. Reflection from an object can change the polarization angle of the returning light. Thus, the system return signal can contain light with different linear polarization states. For example, a first portion of the system return signal can contain light with a first linear polarization state, and a second portion of the system return signal can contain light with a second linear polarization state. The strength of the resulting composite signal is proportional to the cosine squared of the angle between the comparison signal polarization field and the reference signal polarization field. If this angle is 90 degrees, LIDAR data can be lost in the resulting composite signal. However, LIDAR systems can be modified to compensate for changes in the polarization state of the LIDAR output signal.

[0050] FIG. 3 illustrates the LIDAR system of FIG. 3 with a LIDAR adapter modified for use with the LIDAR chip of FIG. 1C. The LIDAR adapter includes a beam splitter 120 that receives the system return signal from the circulator 100. The beam splitter 120 splits the system return signal into a first portion and a second portion. Suitable beam splitters include, but are not limited to, a Wollaston prism and a MEMS-based beam splitter.

[0051] A first portion of the system return signal is directed to a comparison waveguide 18 on the LIDAR chip and serves as the first LIDAR input signal described in Figure 1C. A second portion of the system return signal is directed to a polarization rotator 122, which outputs a second LIDAR input signal that is directed to a second input waveguide 76 on the LIDAR chip and serves as the second LIDAR input signal.

[0052] The beam splitter 120 may be a polarizing beam splitter. One example of a polarizing beam splitter is constructed so that a first portion of the system return signal has a first polarization state but is free or substantially free of a second polarization state, and a second portion of the system return signal has a second polarization state but is free or substantially free of the first polarization state. The first and second polarization states may be linear polarization states. The second polarization state may be different from the first polarization state. For example, the first polarization state may be TE and the second polarization state may be TM. Or, the first polarization state may be TM and the second polarization state may be TE. In some cases, the laser light source is linearly polarized, resulting in the LIDAR output signal having the first polarization state. Suitable beam splitters include, but are not limited to, Wollaston prisms and MEM-based polarizing beam splitters.

[0053] The polarization rotator can be configured to change the polarization state of the first portion of the system return signal and / or the second portion of the system return signal. For example, the polarization rotator 122 shown in FIG. 3 can be configured to change the polarization state of the second portion of the system return signal from the second polarization state to the first polarization state. As a result, the second LIDAR input signal has the first polarization state but does not have, or is substantially not having, the second polarization state. Thus, the first LIDAR input signal and the second LIDAR input signal each have the same polarization state (in this example, the first polarization state). Despite transmitting light of the same polarization state, the first LIDAR input signal and the second LIDAR input signal are associated with different polarization states due to the use of a polarizing beam splitter. For example, the first LIDAR input signal transmits reflected light with the first polarization state, and the second LIDAR input signal transmits reflected light with the second polarization state. As a result, the first LIDAR input signal is associated with the first polarization state, and the second LIDAR input signal is associated with the second polarization state.

[0054] Because the first LIDAR input signal and the second LIDAR transmit light with the same polarization state, the comparison signal derived from the first LIDAR input signal has the same polarization angle as the comparison signal derived from the second LIDAR input signal.

[0055] Suitable polarization rotators include, but are not limited to, polarization-maintaining fiber rotation, Faraday rotators, half-wave plates, MEM-based polarization rotators, integrated optic polarization rotators using asymmetric Y-junctions, Mach-Zehnder interferometers, and multimode interference couplers.

[0056] Because the outgoing LIDAR signal is linearly polarized, the first reference signal can have the same linear polarization state as the second reference signal. Additionally, components on the LIDAR adapter can be selected such that the first reference signal, the second reference signal, the comparison signal, and the second comparison signal each have the same polarization state. In the example disclosed in connection with FIG. 3, the first comparison signal, the second comparison signal, the first reference signal, and the second reference signal can each have light of a first polarization state.

[0057] As a result of the above configuration, the first composite signal generated by the first processing unit 46 and the second composite signal generated by the second processing unit 48 are each generated by combining a reference signal and a comparison signal in the same polarization state, thereby providing a desired pulsation between the reference signal and the comparison signal. For example, the composite signal may be generated by combining a first reference signal and a first comparison signal in a first polarization state, excluding or substantially excluding light in a second polarization state. Alternatively, the composite signal may be generated by combining a first reference signal and a first comparison signal in a second polarization state, excluding or substantially excluding light in the first polarization state. Similarly, the second composite signal includes a second reference signal and a second comparison signal in the same polarization state, thereby providing a desired pulsation between the reference signal and the comparison signal. For example, the second composite signal may be generated by combining a second reference signal and a second comparison signal in a first polarization state, excluding or substantially excluding light in the second polarization state. Alternatively, the second composite signal is generated by combining a second reference signal and a second comparison signal in a second polarization state, which excludes or substantially excludes light in the first polarization state.

[0058] With the above configuration, LIDAR data for a single sample area within the field of view is generated from multiple different composite signals (i.e., a first composite signal and a second composite signal) from the sample area. In some cases, measuring LIDAR data for the sample area includes the electronics combining the LIDAR data from the different composite signals (i.e., the composite signal and the second composite signal). Combining the LIDAR data can include taking the mean, median, or mode of the LIDAR data generated from the different composite signals. For example, the electronics can average a distance between the LIDAR system and a reflecting object measured from the composite signal with a distance measured from the second composite signal, and / or the electronics can average a radial velocity between the LIDAR system and a reflecting object measured from the composite signal with a radial velocity measured from the second composite signal.

[0059] In some cases, measuring LIDAR data for the sample area includes the electronics identifying one or more composite signals (i.e., the composite signal and / or the second composite signal) as a source of LIDAR data that most closely represents reality (representative LIDAR data). The electronics can use the LIDAR data from the identified composite signals as representative LIDAR data for further processing. For example, the electronics can identify a signal (the composite signal or the second composite signal) with a large amplitude as having representative LIDAR data and use the LIDAR data from the identified signal for further processing by the LIDAR system. In some cases, the electronics combines the identification of the composite signal and the representative LIDAR data with combining LIDAR data from different LIDAR signals. For example, the electronics can identify each composite signal with an amplitude above an amplitude threshold as having representative LIDAR data, and if two or more composite signals are identified as having representative LIDAR data, the electronics can combine the LIDAR data from each identified composite signal. If one composite signal is identified as having representative LIDAR data, the electronics can use the LIDAR data from that composite signal as the representative LIDAR data. If none of the composite signals are identified as representative LIDAR data, the electronics can discard the LIDAR data for the sample regions associated with those composite signals.

[0060] While FIG. 3 is illustrated with components arranged such that the first comparison signal, the second comparison signal, the first reference signal, and the second reference signal each have a first polarization state, other configurations of the components in FIG. 3 can be used such that a composite signal is generated by combining the reference signal and the comparison signal with the same linear polarization state, and a second composite signal is generated by combining the reference signal and the comparison signal with the same linear polarization state. For example, the beam splitter 120 can be configured such that the second portion of the system return signal has a first polarization state and the first portion of the system return signal has a second polarization state, the polarization rotator receives the first portion of the system return signal, and the output LIDAR signal has a second polarization state. In this example, the first LIDAR input signal and the second LIDAR input signal each have a second polarization state.

[0061] The above system configuration causes the first portion of the system return signal and the second portion of the system return signal to be induced into different composite signals, such that the first portion of the system return signal and the second portion of the system return signal are associated with different polarization states, but the electronics can process the respective composite signals such that the LIDAR system compensates for changes in the polarization state of the LIDAR output signal in response to reflections of the LIDAR output signal.

[0062] The LIDAR adapter of FIG. 3 can include additional optical components, including passive optical components. For example, the LIDAR adapter can include an optional third lens 126. The third lens 126 can be configured to couple the second LIDAR output signal to a desired location. In some cases, the third lens 126 can focus or collimate the second LIDAR output signal to a desired location. For example, the third lens 126 can be configured to focus or collimate the second LIDAR output signal onto the facet 52 of the second comparison waveguide 50. The LIDAR adapter also includes one or more redirecting elements 124, such as mirrors and prisms. FIG. 3 illustrates a LIDAR adapter including a mirror as the redirecting element 124, which redirects a second portion of the system return signal from the circulator 100 onto the facet 52 of the second comparison waveguide 50 and / or the third lens 126.

[0063] When a LIDAR system includes a LIDAR chip and a LIDAR adapter, the LIDAR chip, electronics, and LIDAR adapter can be disposed on a common mount. Suitable common mounts include, but are not limited to, glass, metal, silicon, and ceramic plates. As an example, FIG. 4 is a top view of a LIDAR system including the LIDAR chip and electronics 32 of FIG. 1A and the LIDAR adapter of FIG. 2 mounted on a common support 140. While the electronics 32 is shown mounted on the common support, all or a portion of the electronics can be positioned remotely from the common support. When the light source 4 is positioned remotely from the LIDAR chip, the light source can be mounted on or remote from the common support 140. Suitable methods for mounting the LIDAR chip, electronics, and / or LIDAR adapter on the common support include, but are not limited to, epoxy, solder, and mechanical clamps.

[0064] A LIDAR system may include components including additional passive and / or active optical components. For example, a LIDAR system may include one or more components that receive a LIDAR output signal from a LIDAR chip or a LIDAR adapter. A portion of the LIDAR output signal from the one or more components may function as a system output signal. For example, a LIDAR system may include one or more beam steering units that receive a LIDAR output signal from a LIDAR chip or a LIDAR adapter and output all or a portion of the LIDAR output signal that functions as a system output signal. For example, FIG. 4 shows a beam steering unit 142 that receives a LIDAR output signal from a LIDAR adapter. While FIG. 4 shows the beam steering unit disposed on a common support 140, the beam steering unit may be disposed on the LIDAR chip, on the LIDAR adapter, outside the LIDAR chip, or outside the common support 140. Suitable beam steering units include, but are not limited to, a movable mirror, a MEMS mirror, an optical phased array (OPA), an actuator that moves the LIDAR chip, the LIDAR adapter, and / or the common support.

[0065] The electronics can operate one or more beam steering units 142 to steer the system output signal to different sample areas 144. The sample areas can extend away from the LIDAR system up to a maximum distance configured for the LIDAR system to provide reliable LIDAR data. The sample areas can be joined together to define a field of view. For example, the field of view of a LIDAR system can include or consist of the space occupied by a combination of the sample areas.

[0066] 5A-5C show an example of a suitable processing unit for use as all or part of a processing unit selected from the group consisting of processing unit 22, first processing unit 46, and second processing unit 48. The processing unit receives a comparison signal from a comparison waveguide 196 and a reference signal from a reference waveguide 198. The comparison waveguide 18 and reference waveguide 20 shown in FIGS. 1A and 1B can function as the comparison waveguide 196 and reference waveguide 198, the comparison waveguide 18 and first reference waveguide 42 shown in FIG. 1C can function as the comparison waveguide 196 and reference waveguide 198, or the second comparison waveguide 50 and second reference waveguide 44 shown in FIG. 1C can function as the comparison waveguide 196 and reference waveguide 198.

[0067] The processing section includes a second splitter 200 that splits the comparison signal transmitted in the comparison waveguide 196 between a first comparison waveguide 204 and a second comparison waveguide 206. The first comparison waveguide 204 transmits a first portion of the comparison signal to an optical coupling section 211. The second comparison waveguide 208 transmits a second portion of the comparison signal to a second optical coupling section 212.

[0068] The processing section includes a first splitter 202 that splits a reference signal transmitted in the reference waveguide 198 between a first reference waveguide 204 and a second reference waveguide 206. The first reference waveguide 204 transmits a first portion of the reference signal to an optical coupling section 211. The second reference waveguide 208 transmits a second portion of the reference signal to a second optical coupling section 212.

[0069] The second optical coupler 212 combines the second portion of the comparison signal with the second portion of the reference signal to generate a second composite signal. Due to the frequency difference between the second portion of the comparison signal and the second portion of the reference signal, the second composite signal pulsates between the second portion of the comparison signal and the second portion of the reference signal.

[0070] The second optical coupler 212 also splits the resulting second composite signal into a first auxiliary detector waveguide 214 and a second auxiliary detector waveguide 216. The first auxiliary detector waveguide 214 transmits a first portion of the second composite signal to a first auxiliary optical sensor 218, which converts the first portion of the second composite signal into a first auxiliary electrical signal. The second auxiliary detector waveguide 216 transmits a second portion of the second composite signal to a second auxiliary optical sensor 220, which converts the second portion of the second composite signal into a second auxiliary electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0071] In some cases, the second optical coupling unit 212 splits the second composite signal such that the portion of the comparison signal included in the first portion of the second composite signal (i.e., the second portion of the comparison signal) is phase-shifted by 180 degrees relative to the portion of the comparison signal in the second portion of the second composite signal (i.e., the second portion of the comparison signal), but the portion of the reference signal in the second portion of the second composite signal (i.e., the second portion of the reference signal) is not phase-shifted relative to the portion of the reference signal in the first portion of the second composite signal (i.e., the second portion of the reference signal). Alternatively, the second optical coupling unit 212 splits the second composite signal such that the portion of the reference signal in the first portion of the second composite signal (i.e., the second portion of the reference signal) is phase-shifted by 180 degrees relative to the portion of the reference signal in the second portion of the second composite signal (i.e., the second portion of the reference signal), but the portion of the comparison signal in the first portion of the second composite signal (i.e., the second portion of the comparison signal) is not phase-shifted relative to the portion of the comparison signal in the second portion of the second composite signal (i.e., the second portion of the comparison signal). Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0072] The first optical coupler 211 combines the first portion of the comparison signal with the first portion of the reference signal to generate a first composite signal. Due to the frequency difference between the first portion of the comparison signal and the first portion of the reference signal, the first composite signal pulsates between the first portion of the comparison signal and the first portion of the reference signal.

[0073] The first optical coupler 211 also splits the first composite signal into a first detector waveguide 221 and a second detector waveguide 222. The first detector waveguide 221 transmits a first portion of the first composite signal to a first optical sensor 223, which converts the first portion of the second composite signal into a first electrical signal. The second detector waveguide 222 transmits a second portion of the second composite signal to a second optical sensor 224, which converts the second portion of the second composite signal into a second electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0074] In some cases, the optical combiner 211 splits the first composite signal so that the portion of the comparison signal included in the first portion of the composite signal (i.e., the first portion of the comparison signal) is phase-shifted by 180 degrees relative to the portion of the comparison signal in the second portion of the composite signal (i.e., the first portion of the comparison signal), but the portion of the reference signal in the first portion of the composite signal (i.e., the first portion of the reference signal) is not phase-shifted relative to the portion of the reference signal in the second portion of the composite signal (i.e., the first portion of the reference signal). Alternatively, the optical combiner 211 splits the composite signal so that the portion of the reference signal in the first portion of the composite signal (i.e., the first portion of the reference signal) is phase-shifted by 180 degrees relative to the portion of the reference signal in the second portion of the composite signal (i.e., the first portion of the reference signal), but the portion of the comparison signal in the first portion of the composite signal (i.e., the first portion of the comparison signal) is not phase-shifted relative to the portion of the comparison signal in the second portion of the composite signal (i.e., the first portion of the comparison signal).

[0075] When the second optical coupler 212 splits the second composite signal such that the portion of the comparison signal in the first portion of the second composite signal is phase-shifted by 180 degrees relative to the portion of the comparison signal in the second portion of the second composite signal, the optical coupler 211 also splits the composite signal such that the portion of the comparison signal in the first portion of the composite signal is phase-shifted by 180 degrees relative to the portion of the comparison signal in the second portion of the composite signal. 98 When the second optical coupler 212 splits the second composite signal such that the portion of the reference signal in the first portion of the second composite signal is phase-shifted by 180 degrees relative to the portion of the reference signal in the second portion of the second composite signal, the optical coupler 211 also splits the composite signal such that the portion of the reference signal in the first portion of the composite signal is phase-shifted by 180 degrees relative to the portion of the reference signal in the second portion of the composite signal.

[0076] The first reference waveguide 210 and the second reference waveguide 208 are configured to provide a phase shift between the first portion of the reference signal and the second portion of the reference signal. For example, the first reference waveguide 210 and the second reference waveguide 208 can be configured to provide a 90-degree phase shift between the first portion of the reference signal and the second portion of the reference signal. As an example, one reference signal portion can be an in-phase component and the other reference signal portion can be a quadrature component. Thus, one reference signal portion can be a sine function and the other reference signal portion can be a cosine function. As an example, the first reference waveguide 210 and the second reference waveguide 208 are configured such that the first reference signal portion is a cosine function and the second reference signal portion is a sine function. Thus, the reference signal portion in the second composite signal is phase-shifted relative to the reference signal portion in the first composite signal, but the comparison signal portion in the first composite signal is not phase-shifted relative to the comparison signal portion in the second composite signal.

[0077] The first optical sensor 223 and the second optical sensor 224 can be connected as a balanced detector, and the first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 can also be connected as a balanced detector. For example, FIG. 5B shows a schematic diagram of the relationship between the electronics, the first optical sensor 223, the second optical sensor 224, the first auxiliary optical sensor 218, and the second auxiliary optical sensor 220. Although a photodiode symbol is used to represent the first optical sensor 223, the second optical sensor 224, the first auxiliary optical sensor 218, and the second auxiliary optical sensor 220, one or more of these sensors may have other configurations. In some cases, all of the components shown in the schematic diagram of FIG. 5B are included on the LIDAR chip. In some cases, the components shown in the schematic diagram of FIG. 5B are distributed between the LIDAR chip and electronics located off the LIDAR chip.

[0078] The electronics connect the first optical sensor 223 and the second optical sensor 224 as a first balance detector 225, and connect the first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 as a second balance detector 226. Specifically, the first optical sensor 223 and the second optical sensor 224 are connected in series. The first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 are also connected in series. The series connection in the first balance detector communicates with a first data line 228, which carries the output from the first balance detector as a first data signal. The series connection in the second balance detector communicates with a second data line 232, which carries the output from the second balance detector as a second data signal. The first data signal is an electrical representation of the first composite signal, and the second data signal is an electrical representation of the second composite signal. Thus, the first data signal includes contributions from the first waveform and the second waveform, and the second data signal is a combination of the first waveform and the second waveform. A portion of a first waveform in the first data signal is phase-shifted relative to a portion of the first waveform in the first data signal, while a portion of a second waveform in the first data signal is in phase with a portion of the second waveform in the first data signal. For example, the second data signal includes a portion of a reference signal that is phase-shifted relative to another portion of the reference signal included in the first data signal. The second data signal also includes a portion of a comparison signal that is in phase with another portion of the comparison signal included in the first data signal. The first and second data signals are pulsating as a result of the pulsation between the comparison signal and the reference signal, i.e., the pulsation in the first and second composite signals.

[0079] The electronics 32 includes a transform mechanism 238 configured to perform a mathematical transform on the first and second data signals. For example, the mathematical transform may be a complex Fourier transform with the first and second data signals as inputs. The first data signal is the in-phase component and the second data signal is its quadrature component, so that the first and second data signals act together as a complex data signal. Thus, the first data signal is the real component of the input and the second data signal is the imaginary component of the input.

[0080] The conversion mechanism 238 includes a first analog-to-digital converter (ADC) 264 that receives the first data signal from the first data line 228. The first analog-to-digital converter (ADC) 264 converts the first data signal from analog format to digital format and outputs a first digital data signal. The conversion mechanism 238 includes a second analog-to-digital converter (ADC) 266 that receives the second data signal from the second data line 232. The second analog-to-digital converter (ADC) 266 converts the second data signal from analog format to digital format and outputs a second digital data signal. The first digital data signal is a digital representation of the first data signal, and the second digital data signal is a digital representation of the second data signal. Thus, the first digital data signal and the second digital data signal act together as a complex signal, where the first digital data signal acts as the real component of the complex signal and the second digital data signal acts as the imaginary component of the complex data signal.

[0081] The conversion mechanism 238 includes a conversion unit 268 that receives a complex data signal. For example, the conversion unit 268 receives as an input a first digital data signal from a first analog-to-digital converter (ADC) 264 and a second digital data signal from a second analog-to-digital converter (ADC) 266. The conversion unit 268 can be configured to perform a mathematical transform on the complex signal, thereby converting it from the time domain to the frequency domain. The mathematical transform can be a complex transform, such as a complex Fast Fourier Transform (FFT). A complex transform, such as a complex Fast Fourier Transform (FFT), provides an unambiguous solution to the shift in frequency of the LIDAR input signal relative to the LIDAR output signal caused by the radial velocity between the reflecting object and the LIDAR tip. The electronics use one or more frequency peaks output from the conversion unit 268 to generate LIDAR data (the distance and / or radial velocity between the reflecting object and the LIDAR tip or system) for further processing. The converter 268 may use firmware, hardware, software, or a combination thereof to perform the specified functions.

[0082] The electronics 32 includes a peak detector 270 that receives the output from the transform unit 268. The peak detector 270 is configured to detect peaks in the output of the transform unit 268 to identify the pulsation frequency of the composite optical signal. The mathematical transform can be a complex transform, such as a complex Fast Fourier Transform (FFT). A complex transform, such as a complex Fast Fourier Transform (FFT), provides an unambiguous solution for the pulsation frequency of the composite optical signal. In some cases, the peak detector 270 can store the pulsation frequencies in memory 271 for later use by the LIDAR data generator 274. As described in more detail below, each pulsation frequency can be stored as fm, where m represents a period index. The LIDAR data generator 274 uses the pulsation frequencies to generate LIDAR data (the distance and / or line-of-sight velocity between a reflecting object and the LIDAR tip or LIDAR system). Suitable memory 271 includes, but is not limited to, a buffer. The peak detector 270 can perform its designated functions using firmware, hardware, software, or a combination thereof.

[0083] 5A shows an optical combiner combining a portion of the reference signal and a portion of the comparison signal, the processing unit may include a single optical combiner combining the reference signal and the comparison signal to form a composite signal. As a result, at least a portion of the reference signal and at least a portion of the comparison signal may be combined to form the composite signal. The combined portion of the reference signal may be the entire reference signal or a portion of the reference signal, and the combined portion of the comparison signal may be the entire comparison signal or a portion of the comparison signal.

[0084] The electronics adjust the frequency of the system output signal over time. The system output signal has a frequency versus time pattern with a repeating cycle. Figure 5C shows an example of a suitable frequency versus time pattern for the system output signal. The fundamental frequency (f o ) may be the frequency of the system output signal at the start of the cycle.

[0085] FIG. 5C shows cycle j and cycle j+1 5C shows frequency versus time for a sequence of two cycles labeled j, where j represents the cycle index. In some cases, as shown in FIG. 5C, the frequency versus time pattern is repeated for each cycle. The illustrated cycles do not include rearrangement periods and / or rearrangement periods are not interspersed between cycles. As a result, FIG. 5C shows the results of a continuous scan.

[0086] Each cycle is associated with a period index m, and m It contains M data periods, denoted as M. Suitable values ​​for M are M > In the example of Figure 5C, M=3. As a result, each cycle m The cycle includes three data periods denoted as m, where m=1, 2, and 3. In some cases, as shown in FIG. 5C, the frequency versus time patterns of corresponding data periods in different cycles are the same. Corresponding data periods are data periods with the same period index. As a result, each data period DP1 can be considered a corresponding data period, and the associated frequency versus time patterns are the same in FIG. 5C. At the end of the cycle, the electronics returns the frequency to the same frequency level as at the start of the previous cycle.

[0087] Data Period DP m During this period, the electronics operate the light source such that the frequency of the system output signal varies linearly as a function of time. For example, during the data period DP m During this time, the frequency of the system output signal is maintained at a constant or substantially constant rate α mThe chirp rate can vary at a constant rate (chirp rate). The chirp rate can last for all or part of a data period. For example, during a data period labeled DP1, the electronics operate the light source so that the frequency of the system output signal varies at a linear rate α1; during a data period labeled DP2, the electronics operate the light source so that the frequency of the system output signal varies at a linear rate α2; and during a data period labeled DP3, the electronics operate the light source so that the frequency of the system output signal varies at a linear rate α3. In some cases, the chirp rate can vary from α1 to α M is from α1 to α M The sum of α1, α2, and α3 is selected to be zero. For example, if M is 3, α1, α2, and α3 are selected to be α1+α2+α3=0, as shown in FIG. 5C. When α1+α2+α3=0, the frequency returns to the same frequency level as at the beginning of the previous cycle. In some cases, α1>0, α2<0, and α3≠0, or α1<0, α2>0, and α3≠0.

[0088] Figure 5C shows the SR associated with the sample region index k. k The sample area is denoted as SR. k ~SR k+1 Each sample area is illuminated with a system output signal during the data period shown in FIG. 5C as associated with that sample area. For example, sample area SR k+1 is a cycle j+1 During the data periods marked DP1, DP2, and DP3 in the k+1 The sample area marked with is the cycle j+1 The sample area index k can be assigned to the time. For example, the sample areas can be illuminated by the system output signal in the order indicated by the index k. As a result, the sample area SR 10 is after sample area SR9 and SR 11Although Figure 5C shows one sample area being illuminated during one cycle, multiple different sample areas can be illuminated during one cycle.

[0089] The frequency output from the complex Fourier transform represents the beat frequency of a composite signal that includes the comparison signal beat relative to the reference signal. Beat frequencies from two or more different data periods associated with the same sample area can be combined to generate LIDAR data. For example, for sample area SR, k The pulsation frequency measured from DP1 during irradiation of the sample area SR k By combining the beating frequencies measured from DP2 during irradiation of the sample area SR k As an example, LIDAR data can be measured for a data period DP m The pulsation frequency in the pulsation can be expressed as follows: m = 2α m R / c-2υ / λ, where m is the periodic index, R represents the distance between the LIDAR system and the object, c represents the speed of light, υ represents the radial velocity between the reflecting object and the LIDAR system, λ represents the wavelength of the system output signal, and the direction from the reflecting object towards the LIDAR system is assumed to be the positive direction.

[0090] The data period associated with a sample area includes multiple target data periods and at least one check data period. In FIG. 5C, DP1 and DP2 associated with each sample area function as target sample areas, and DP3 associated with the sample area functions as a check data period. The rate of change of the frequency of the system output signal during data period m (α m) may vary for each target data period. While FIG. 5C shows two target data periods, a sample area may be illuminated by the system output signal for more than one target data period. Thus, in some cases, a cycle includes more than one target data period. The rate of change of the frequency of the system output signal during a check data period may be different from the rate of change of the frequency of the system output signal during all or part of a target data period. Thus, the rate of change of the frequency of the system output signal during each data period associated with the same sample area may be different. In some cases, the rate of change of the frequency of the system output signal during a check data period is not zero.

[0091] As can be seen from data period DP1 in Figure 5C, the frequency of the system output signal can be increased during one of the target data periods associated with the sample region. The beat frequency of the composite signal during the target data period (increased data period) during which the frequency of the system output signal is increased is f ub The growth rate is expressed as α ub As a result, in the example of FIG. 5C, f1= f ub and α1 = α ub As is evident from data period DP2 in FIG. 5C, the frequency of the system output signal can be decreased in one of the data periods of interest associated with the same sample region. The beat frequency of the composite signal in the data period in which the frequency of the system output signal is decreased is f db The rate of decrease is expressed as α db As a result, in the example of Figure 5C, f2 = f db and α2 = α db This becomes:

[0092] The pulsation frequency of the composite signal during the check data period is f chk The rate of change of frequency is expressed as α chk As mentioned above, each data period denoted by DP3 in FIG. 5C can function as a check data period for one of the sample regions. As a result, in the example of FIG. 5C, f3=f chk and α3 = α chkCheck data period (f chk ) and the rate of change of the frequency during the check data period (α chk ) is the pulsation frequency f ub and f db For example, the same sample area that is illuminated during the check data period is also illuminated during the associated target data period. For example, in FIG. 5C, SR k The beat frequencies (f1, f2, and f3) resulting from data periods denoted DP1, DP2, and DP3 within a sample domain denoted DP1, DP2, and DP3 are related.

[0093] The above formula 1(f m = 2α m In the case of R / c-2υ / λ), the values ​​of υ and R are unknown. As a result, the results of Equation 1 from two different data periods associated with a sample area can be used to calculate the values ​​of υ and R for a data period. Solving these equations for the distance (R) between the LIDAR system and the object yields Equation 2: R=c(f ub -f db ) / (2(α ub -α db )) is obtained. Furthermore, solving these equations for the line-of-sight velocity (υ) between the reflecting object and the LIDAR system gives Equation 3: υ = λ(α db f ub -α ub f db ) / (2(α ub -α db)) is obtained. As shown in FIG. 5B, the electronics include a LIDAR data generator 274 that receives the pulsation frequency from memory 271 and / or peak detector 270. The LIDAR data generator 274 can use the pulsation frequency in the above equation to calculate the distance and / or radial velocity (R and / or υ) of the illuminated sample area to provide the pulsation frequency. The obtained distance and / or radial velocity (R and / or υ) values ​​can represent candidate LIDAR data for the sample area. For example, the obtained distance (R) can serve as a candidate distance, and / or the obtained radial velocity (υ) can serve as a candidate radial velocity. The candidate LIDAR data can be calculated using f ub , f db and f chk The LIDAR data generator 274 may use firmware, hardware, software, or a combination thereof to perform the specified functions.

[0094] The electronics may include a LIDAR data verifier 276 that receives candidate LIDAR data from the LIDAR data generator 274. The LIDAR data verifier 276 derives the check period beat frequency (cf chk ) and other pulsating frequencies can also be received.

[0095] The LIDAR data verifier 276 can use the check data period associated with a sample region to determine whether the associated candidate LIDAR data is valid for that sample region. For example, the LIDAR data verifier 276 can determine the comparative check period beat frequency (cf chk ) can be calculated. chk ) is the frequency change rate α during the check data period chk can be measured by substituting into Equation 1, and Equation 4:cf chk = 2α chkAs a result, the LIDAR data validator 276 obtains the comparison check period beating frequency (cf chk ) to cf chk = 2α chk It can be calculated as R / c-2υ / λ, where R represents the candidate distance of the sample region and υ represents the candidate radial velocity of the sample region.

[0096] The LIDAR data validator 276 compares the sample area and checks the periodic beating frequency (cf chk ) can be used to determine whether the candidate LIDAR data for the sample region is valid. For example, the LIDAR data validator 276 may use the comparison check period beating frequency (cf chk ) for the same data period. chk ) and comparison check period pulsation frequency (cf chk For example, the LIDAR data verifier 276 may compare the values ​​of the comparison check period beating frequency (cf chk ) is the check period pulsation frequency (f chk ), the LIDAR data verifier 276 determines that the candidate LIDAR data for the sample region is valid. Thus, the LIDAR data verifier can classify the candidate LIDAR data for the sample region as LIDAR data for the sample region. The LIDAR data verifier 276 determines that the comparison check period beating frequency (cf chk ) is outside the range, the candidate LIDAR data is determined to be invalid for the sample area. As a result, the LIDAR data validator 276 may classify the candidate LIDAR data for the sample area as unusable. The candidate LIDAR data classified as unusable is effectively removed from the final LIDAR data for the sample area within the field of view of the LIDAR system. The LIDAR data validator 276 may use firmware, hardware, software, or a combination thereof to perform the specified functions.

[0097] Check period pulsation frequency (f chk ) is an example of a range of values ​​that includes f chk - C1 to f chk + C2, where C1 and C2 are positive constants, and either C1 or C2 may be zero, or one or both may be zero. Therefore, the check period beat frequency (f chk ) and comparison check period pulsation frequency (cf chk ) is compared with the value of the comparison check period beat frequency (cf chk ) is f chk - C1 to f chk + C2. For example, f chk - C1 < cf chk < f chk + Does C2 hold? f chk - C1 < cf chk < f chk If +C2 is true, the LIDAR data verifier can classify the candidate LIDAR data for the sample area as LIDAR data for that sample area. chk - C1 < cf chk < f chk If +C2 is false, the candidate LIDAR data is determined to be invalid for the sample region. The values ​​of C1 and C2 may be the same or different. Suitable values ​​for C1 and / or C2 include, but are not limited to, values ​​greater than or equal to 0.01 MHz or 0.5 MHz, and less than or equal to 2 MHz or 100 MHz. The values ​​of C1 and C2 may be selected depending on the LIDAR system.

[0098] The validation performed by the LIDAR data validator 276 can reduce the presence of edge errors in the LIDAR data within the field of view. FIG. 5D illustrates edge errors that may occur during the calculation of LIDAR data. FIG. 5D illustrates two different objects positioned within the field of view of the LIDAR system. The LIDAR system outputs a system output signal that is scanned in the direction of the solid line labeled "Scan." The system output signal is a SR k-1 and SR k A series of sample areas, denoted as , are scanned.

[0099] The collection of sample areas scanned by the system output signals constitutes the field of view of the LIDAR system. Objects within the field of view can change over time. As a result, the position of the sample areas is measured relative to the LIDAR system, not relative to the atmosphere in which the LIDAR system is located. For example, the sample areas can be defined as located within a range of angles relative to the LIDAR system. The dashed lines in Figure 5D indicate that scanning the sample areas within the field of view can be repeated over multiple scan cycles. Thus, if objects within the field of view move and / or change, the system output signals can be scanned through the same sample areas during each scan cycle. The sample areas within the field of view can be scanned in the same order during different scan cycles, or in different orders during different scan cycles.

[0100] In Figure 5D, the portion of each sample region corresponding to a data period is labeled DP1, DP2, or DP3. The chirp rate during data period DP1 is α1, the chirp rate during data period DP2 is α2, and the chirp rate during data period DP3 is α3. The duration of a data period may be equal to the duration of the chirp in that data period.

[0101] Due to the movement of the system output signal, the system output signal is k-1from the state incident on the object 1 during irradiation of the sample area SR k The sample area SR changes to a state where it is incident on the object 2 during irradiation. k-1 During illumination, the system output signal is incident on different objects for part of data period DP1 and part of data period DP2. k-1 The change in the object receiving the system output signal during the illumination of the sample area SR k-1 For example, Figure 5D shows that the R k-1 From R k It includes a dashed line labeled up to, where R k However, the sample area SR k represents the distance measured by the electronics between the LIDAR system and the object as a result of the system output signal transmitted during R. k-1 As is evident from the distances denoted as , changes in the object illuminated by the system output signal while illuminating a sample area can cause errors in the distance measured at that sample area. Similar errors also occur in the radial velocity calculated at that sample area.

[0102] The LIDAR data error shown in Figure 5D is due to the system output signal being incident on the edge of an object during illumination of the sample area. As a result, this error can be considered an edge-effect error. While this error is shown as being caused by different objects, it can also be caused by a single object. For example, scanning the system output signal across the edge of an object during illumination of the sample area can result in the system output signal being incident on a different surface of the object, which can also cause an error.

[0103] Applying one or more check criteria reduces errors from edge effects. For example, the comparison check period beat frequency (cf chk ) is the check period pulsation frequency (f chk ) value, but is not a function of the value of the beat frequency in the check period, but rather a function of beat frequencies from multiple different target data periods. As a result, the comparative check period beat frequency (cfchk ) is calculated from the beat frequencies in a plurality of different target data periods. For example, in the above example, the comparison check period beat frequency (cf chk ) is calculated from the pulsation frequencies of the increasing data period and the decreasing data period. As a result, the comparison check period pulsation frequency (cf chk ) is a function of the distance (R) and the line of sight velocity (υ) in the data period other than the check data period. On the other hand, the check period pulsation frequency (f chk ) is a function of the distance (R) and line of sight velocity (υ) values ​​during the check data period. Therefore, if the distance (R) and line of sight velocity (υ) values ​​are consistent in both the check data period and other relevant data periods, the comparison check period beat frequency (f chk ) value is the associated check period beat frequency (f chk For example, if the distance (R) and the line of sight velocity (υ) are constant or substantially constant throughout the check data period, the associated increase data period, and the associated decrease data period, the comparative check period beat frequency (cf chk ) value is the associated check period beat frequency (f chk ) values. Removing candidate LIDAR data whose range (R) and radial velocity (υ) are not constant or substantially constant during illumination of the sample area from the final LIDAR data values ​​in the field of view removes candidate LIDAR data that may result from surface changes in the system output signal during illumination of the sample area, thereby mitigating the presence of edge error effects.

[0104] It has been demonstrated that filtering candidate lidar data whose range (R) and radial velocity (υ) change significantly during illumination of the sample area can reduce other errors that occur when generating lidar data for a field of view. For example, outliers occur when the lidar data for a sample area does not match the lidar data for surrounding sample areas. Outliers do not necessarily occur at the transition between surfaces; they can occur in the center of a surface. As a result, the lidar data for a sample area where the system output signal is incident on a surface can be an outlier, but that lidar data does not match the lidar data for adjacent sample areas where the system output signal is incident on the same surface. It has been demonstrated that the occurrence of outliers can be reduced by removing candidate lidar data whose range (R) and radial velocity (υ) do not remain constant or substantially constant during illumination of the sample area. Extracting these candidate lidar data values ​​from the final lidar data values ​​for the field of view also reduces aliasing.

[0105] 6 is a flow diagram of a LIDAR data refinement process that can be used to filter candidate LIDAR data. At process block 310, a sample region (SR k ) is received. For example, LIDAR data generator 274 can receive the pulsating frequency from memory 271 and / or peak detector 270. As described above, the received pulsating frequency includes two or more target data periods and at least one check data period. For example, if the system output signal has the frequency versus time pattern shown in FIG. 5C, the received pulsating frequency is k The data periods DP1, DP2, and DP3 may include pulsating frequencies (f1, f2, and f3) resulting from the system output signal in the data periods DP1, DP2, and DP3. In some cases, DP1 and DP2 may function as target data periods, and DP3 may function as a check data period. As another example, DP1 and DP3 may function as target data periods, and DP2 may function as a check data period.

[0106] In process block 312, candidate LIDAR data is calculated from the pulsating frequencies obtained from the output of the system output signal during each of a plurality of different data periods of interest. The candidate LIDAR data need not be a function of the pulsating frequencies obtained from the output of the system output signal during the check data period. As a result, the pulsating frequencies obtained from the output of the system output signal during the check data period need not be used as variables in the calculation of the candidate LIDAR data. For example, the LIDAR data generator 274 can use the received pulsating frequencies in combination with Equation 1 and / or Equation 2 above to calculate potential values ​​for the distance (R) between the LIDAR system and an object in the sample region and / or potential values ​​for the radial velocity between the LIDAR system and an object in the sample region. In an example where the system output signal has the frequency versus time pattern shown in FIG. 5C and DP1 and DP2 serve as data periods of interest, f1 in the sample region of interest may be calculated as f in Equation 2 and / or Equation 3. ub and f2 of the sample region of interest can function as f in Equation 2 and / or Equation 3. db It can function as.

[0107] In processing block 314, the pulsation frequency of the composite signal in the check data period (comparison check period pulsation frequency, cf chk ) is calculated. chk The comparison check period beat frequency (cf) can be calculated from the beat frequency obtained from the output of the system output signal in each of a plurality of different target data periods. chk ) does not have to be a function of the beat frequency obtained from the output of the system output signal during the check data period. As a result, the comparison check period beat frequency (cf chk ) does not need to use the beat frequency obtained from the output of the system output signal during the check data period as a variable. For example, the LIDAR data verifier 276 receives candidate LIDAR data from the LIDAR data generator 274 and uses the result in combination with Equation 4 to calculate the comparison check period beat frequency (cf chkAlternatively, the LIDAR data validator 276 can receive the beat frequency from the memory 271 and / or the peak detector 270 and use the received beat frequency in combination with Equations 2, 3, and 4 to calculate the comparison check period beat frequency (cf chk ) can also be calculated.

[0108] In decision block 316, the comparison check period beat frequency (cf chk ) is the pulsation frequency during the check period (check period pulsation frequency, f chk In the example where the system output signal has the frequency versus time pattern shown in FIG. 5C and DP3 serves as the check data period, the comparison check period beat frequency (cf chk ) is f chk (where f3 is f chk For example, the comparison check period beat frequency (cf chk ) by applying one or more check criteria to the comparison check period beat frequency (cf chk ) is the pulsation frequency (f chk For example, as described above, the LIDAR data verifier 276 can determine whether the comparison check period beat frequency (cf chk ) is the check period pulsation frequency (f chk As described above, it can be determined whether the check period beat frequency (f chk ) is an example of a range of values ​​that includes f chk - C1 to f chk + C2, where C1 and C2 are positive constants, and either, one, or both of C1 and C2 may be zero. The LIDAR data verifier 276 determines the comparison check period beating frequency (cf chk ) is determined to be within the range of the above values, the comparison check period beat frequency (cf chk The LIDAR data verifier 276 determines that the comparison check period beating frequency (cf chk) is determined to be outside the range of the above values, the comparison check period beat frequency (cf chk ) does not match the pulsation frequency during the check period.

[0109] The LIDAR data verifier 276 calculates the comparison check period beat frequency (cf chk ) matches the beating frequency during the check period, proceed to process block 318 and classify the candidate LIDAR data for the target sample area as valid. As a result, the candidate LIDAR data for the target sample area serves as the actual LIDAR data for the target sample area. The actual LIDAR data for the target sample area is a value of the distance (R) between the LIDAR system and an object in the sample area and / or a value of the radial velocity between the LIDAR system and an object in the sample area. As a result, if LIDAR data for the sample area within the field of view of the LIDAR system is made available to the application for further processing, the candidate LIDAR data for the target sample area is included as the actual LIDAR data for the sample area.

[0110] The LIDAR data verifier 276 calculates the comparison check period beat frequency (cf chk ) does not match the beating frequency during the check period, proceed to process block 320 and classify the candidate LIDAR data for the target sample area as unavailable. As a result, the candidate LIDAR data for the target sample area does not serve as actual LIDAR data for the target sample area. This classification effectively removes the candidate LIDAR data for the target sample area from the collection of LIDAR data results for the sample area within the field of view of the LIDAR system. As a result, when LIDAR data results for the sample area within the field of view of the LIDAR system become available for further processing by the LIDAR application, the candidate LIDAR data for the target sample area is removed from the LIDAR data results for that field of view.

[0111] The electronics can return from process block 318 or process block 320 to process block 310. In process block 310, the pulsation frequency of the next sample region of interest is received. For example, the LIDAR data generator 274 receives the pulsation frequency of sample region SR k+1 A collection of LIDAR data results for the sample areas in the field of view can be received for further processing in a LIDAR application, with each sample area in the field of view functioning as one of the sample areas of interest. A first portion of the sample areas in the field of view has no LIDAR data results because one or more check criteria are applied to the comparative beating frequencies of these sample areas. This results in a comparative check period beating frequency (cf chk A first result is provided that indicates a discrepancy between the comparative check period beat frequency (cf) and the measured beat frequency associated with the sample area. Meanwhile, for a second portion of the sample area within the field of view, LIDAR data results are generated for applying one or more check criteria to the comparative beat frequency of those sample areas. This results in a comparative check period beat frequency (cf chk ) and the measured beats associated with the sample region is provided. Example LIDAR applications include, but are not limited to, autonomous vehicles, robotics, and industrial applications.

[0112] Although mathematical transformer 268 is disclosed as performing a complex transform on a complex signal, the complex transform can be replaced with a real transform performed on a real signal. As a result, the optical-to-electrical transform assembly of Figure 5A can be simplified by omitting second optical coupling portion 212, comparison waveguide 206, second splitter 202, second reference waveguide 208, first auxiliary optical sensor 218, second auxiliary optical sensor 220, and related components shown in Figures 5A and 5B.

[0113] Suitable electronics 32 include, but are not limited to, controllers including or consisting of analog electrical circuitry, digital electrical circuitry, processors, microprocessors, digital signal processors (DSPs), field programmable gate arrays (FPGAs), computers, microcomputers, or any combination suitable for performing the operational, monitoring, and control functions described above. In some cases, the controller may have access to a memory containing instructions executed by the controller during the performance of the operational, control, and monitoring functions. In some cases, the functions of the LIDAR data generator, data corrector 272, and peak detector may be performed by a field programmable gate array (FPGA), digital signal processor (DSP), application specific integrated circuit, firmware, software, hardware, and combinations thereof. While the electronics are shown as a single component in a single location, they may also include multiple distinct components that are separate from one another and / or located in different locations. Also, as noted above, all or a portion of the disclosed electronics may be included on a chip, including integrated electronics on the chip.

[0114] Suitable platforms for LIDAR chips include, but are not limited to, silica, indium phosphide, and silicon-on-insulator (SOI) wafers. Figure 7 shows a cross-sectional view of a portion of a chip constructed from a silicon-on-insulator wafer. The silicon-on-insulator wafer includes a buried layer 410 between a substrate 412 and an optically transmissive medium 414. In a silicon-on-insulator wafer, the buried layer 410 is silica, while the substrate 412 and optically transmissive medium 414 are silicon. The substrate 412 of an optical platform, such as an SOI wafer, can serve as the base for the entire LIDAR chip. For example, the optical components shown on the LIDAR chips in Figures 1A-1C can be located on the top and / or side surfaces of the substrate 412.

[0115] The portion of the chip shown in Figure 7 includes a waveguide structure adapted for a LIDAR chip constructed from a silicon-on-insulator wafer. A ridge 416 of optical transmission medium 414 extends away from a slab region 418 of the optical transmission medium. The optical signal is confined between the top of ridge 416 and buried oxide layer 410.

[0116] The dimensions of the ridge waveguide are shown in Figure 7. For example, the width of the ridge is denoted by w, and the height is denoted by h. The thickness of the slab region is denoted by T. These dimensions may be more critical than others for LIDAR applications, which require the use of higher levels of optical power than other applications. The ridge width (denoted by w) is greater than 1 μm and less than 4 μm, the ridge height (denoted by h) is greater than 1 μm and less than 4 μm, and the thickness of the slab region is greater than 0.5 μm and less than 3 μm. These dimensions may apply to straight or substantially straight sections of the waveguide, curved sections of the waveguide, and tapered sections of the waveguide. Therefore, these sections of the waveguide are single-mode. However, in some cases, these dimensions may apply to straight or substantially straight sections of the waveguide. Additionally or alternatively, the thickness of the slab in the curved sections of the waveguide may be reduced to reduce optical loss in the curved sections of the waveguide. For example, the curved portion of the waveguide can have a ridge extending away from a slab region having a thickness of 0.0 μm or more and less than 0.5 μm. While the above dimensions generally provide a single-mode structure for the straight or substantially straight portions of the waveguide, tapered and / or curved portions can be multimode. Coupling between multimode and single-mode shapes can be achieved using tapered portions that do not substantially excite higher-order modes. Thus, the waveguide can be constructed such that signals transmitted through the waveguide are transmitted in single mode, even when transmitted through a waveguide portion with multimode dimensions. The waveguide construction disclosed in connection with FIG. 7 is suitable for all or a portion of the waveguide on a LIDAR chip constructed according to FIGS. 1A-1C.

[0117] The optical sensor that interfaces with the waveguide on the LIDAR chip can be mounted on the chip as a separate component. For example, the optical sensor can be a photodiode or an avalanche photodiode. Examples of suitable optical sensor components include, but are not limited to, InGaAs PIN photodiodes or InGaAs APDs (avalanche photodiodes) (both manufactured by Hamamatsu Photonics, Hamamatsu, Japan). These optical sensors can be located in the center of the LIDAR chip. Alternatively, all or a portion of the waveguide terminating in the optical sensor can terminate in a facet at the edge of the chip, and the optical sensor can be mounted on the edge of the chip on the facet so that the optical sensor receives light passing through the facet. The use of an optical sensor that is a separate component from the chip is suitable for all or a portion of the optical sensors selected from the group consisting of the first auxiliary optical sensor 218, the second auxiliary optical sensor 220, the first optical sensor 223, and the second optical sensor 224.

[0118] Instead of a separate optical sensor, all or part of the optical sensor can be integrated on the chip. For example, examples of optical sensors interfacing with ridge waveguides on chips constructed from silicon-on-insulator wafers are described in Optics Express Vol. 15, No. 21, pp. 13965-13971 (2007); U.S. Patent No. 8,093,080 issued January 10, 2012; U.S. Patent No. 8,242,432 issued August 14, 2012; and U.S. Patent No. 6,108,472 issued August 22, 2000, all of which are incorporated herein in their entirety. The use of an optical sensor integrated on the chip is suitable for all or part of the optical sensors selected from the group consisting of auxiliary optical sensor 218, second auxiliary optical sensor 220, first optical sensor 223, and second optical sensor 224.

[0119] The light source 4 interfaced with the utility waveguide 12 can be a laser chip separate from the LIDAR chip and then attached to the LIDAR chip. For example, the light source 4 can be a laser chip attached to the chip using a flip-chip configuration. The use of a flip-chip configuration is suitable when the light source 4 is interfaced with a ridge waveguide on a chip constructed from a silicon-on-insulator wafer. Alternatively, the utility waveguide 12 can include an optical grating (not shown), such as a Bragg grating, that acts as a reflector for an external cavity laser. In these cases, the light source 4 can include a gain element separate from the LIDAR chip and then attached to the LIDAR chip in a flip-chip configuration. Examples of suitable interfaces between flip-chip gain elements and ridge waveguides on chips constructed from silicon-on-insulator wafers are described in U.S. Patent No. 9,705,278, issued July 11, 2017, and U.S. Patent No. 5,991,484, issued November 23, 1999, each of which is incorporated herein in its entirety. If the light source 4 is a gain element or laser chip, the electronics 32 can vary the frequency of the outgoing LIDAR signal by varying the current level applied to the gain element or laser cavity.

[0120] The LIDAR systems described above include multiple optical components, such as a LIDAR chip, a LIDAR adapter, a light source, a light sensor, a waveguide, and an amplifier. In some cases, the LIDAR system includes one or more passive optical components in addition to or in place of the optical components shown. Passive optical components can be solid-state components that do not include moving parts. Suitable passive optical components include, but are not limited to, lenses, mirrors, optical gratings, reflective surfaces, splitters, demultiplexers, multiplexers, polarizers, polarization splitters, polarization rotators, etc. In some cases, the LIDAR system includes one or more active optical components in addition to or in place of the optical components shown. Suitable active optical components include, but are not limited to, optical switches, phase tuners, attenuators, steerable mirrors, steerable lenses, tunable demultiplexers, tunable multiplexers, etc.

[0121] Other embodiments, combinations, and modifications of the present invention will occur to those skilled in the art in light of these teachings. Accordingly, the present invention is limited only by the following claims, which include all such embodiments and modifications, when viewed in conjunction with the above specification and accompanying drawings.

Claims

1. 1. A method of operating a LIDAR system, comprising: transmitting a system output signal from the LIDAR system such that a sample area is illuminated by the system output signal; during illumination of the sample area, the system output signal includes one check data period and a plurality of target data periods; the frequency of the system output signal varies at different rates during the data period of interest; combining light returning from the system output signal to the LIDAR system with light from a reference signal to generate a pulsatile signal pulsating at a pulsatile frequency; the reference signal includes light that is not emitted from the LIDAR system; and calculating a comparative beat frequency, the comparison pulsation frequency is close to the value of the pulsation frequency of the pulsation signal during the check data period; The comparative beat frequency is calculated using beat frequencies of the beat signal from a plurality of different data periods of interest. A method comprising:

2. 2. The method of claim 1, wherein the comparative beat frequency is calculated such that when the distance and / or line of sight velocity between the LIDAR system and an object located within the sample area during the target data period matches the distance and / or line of sight velocity between the LIDAR system and the object during the check data period, the comparative beat frequency value matches the beat frequency during the check data period.

3. The method of claim 1 , further comprising comparing the comparison beat frequency value with a beat frequency value of the beat signal during the check data period.

4. The method of claim 3 , further comprising determining whether the comparison beat frequency is within a range of values, the range of values ​​including the value of the beat frequency of the beat signal during the check data period.

5. calculating candidate LIDAR data from a pulsatile frequency of the pulsatile signal during the data period of interest, the candidate LIDAR data indicating a potential radial velocity and / or a potential distance between the LIDAR system and an object within a sample volume; and classifying the candidate LIDAR data as not representing LIDAR data of the sample region in response to the comparative beat frequency being outside the range of values, the LIDAR data being indicative of a radial velocity and / or a distance between the LIDAR system and the object; The method of claim 4 further comprising:

6. calculating candidate LIDAR data from a pulsatile frequency of the pulsatile signal during the data period of interest, the candidate LIDAR data indicating a potential radial velocity and / or a potential distance between the LIDAR system and an object within a sample volume; and classifying the candidate LIDAR data such that the candidate LIDAR data represents LIDAR data for the sample area according to the comparative beat frequency being within the range of values, the LIDAR data indicating a radial velocity and / or a distance between the LIDAR system and the object; The method of claim 4 further comprising:

7. 10. The method of claim 1, further comprising calculating LIDAR data from the pulsatile frequency of the pulsatile signal during a plurality of different target data periods, the LIDAR data indicating a line-of-sight velocity and / or a distance between the LIDAR system and an object within a sample volume.

8. The method of claim 7 , wherein the calculation of the LIDAR data excludes the pulsatile frequency of the pulsatile signal during the check data period.

9. 10. The method of claim 1, wherein the sample area is one of a plurality of different sample areas sequentially illuminated by the system output signal, and Calculating the comparative beat frequency for each sample region; and calculating the candidate LIDAR data for each different sample area; the candidate LIDAR data for each sample region is calculated from beat frequencies resulting from illumination of the sample region during a plurality of different data periods; the candidate LIDAR data for each sample area indicates a potential radial velocity and / or a potential distance between the LIDAR system and an object in the sample area; the LIDAR data for each sample area indicates a line-of-sight velocity and / or a distance between the LIDAR system and an object within the sample area; and Applying one or more check criteria to each comparison beat frequency; providing a first result in response to applying the one or more check criteria to the comparative beat frequencies of each sample area in the first portion of the sample area, and classifying the candidate LIDAR data for each sample area in the first portion of the sample area such that the candidate LIDAR data for the sample area in the first portion of the sample area is representative of LIDAR data for the sample area in the first portion of the sample area; Also providing a second result in response to applying the one or more check criteria to the comparative beat frequencies of each sample area in the second portion of the sample area, and classifying the candidate LIDAR data for each sample area in the second portion of the sample area such that the candidate LIDAR data for the sample area in the second portion of the sample area is not representative of LIDAR data for the sample area in the second portion of the sample area; The method further comprises:

10. The method of claim 1 , wherein a rate of change of the frequency of the system output signal during the check data period is different from a rate of change of the frequency of the system output signal during a portion of the target data period.

11. 1. A LIDAR system configured to output a system output signal such that a sample area is illuminated by the system output signal, during illumination of the sample area, the system output signal includes one check data period and multiple target data periods; the frequencies of the system output signals change at different rates during the data period of interest; the LIDAR system includes an optical combiner that combines light returning from a system output signal to the LIDAR system with light from a reference signal to generate a pulsatile signal pulsating at a pulsatile frequency; a LIDAR system, wherein the reference signal includes light that is not emitted from the LIDAR system; and an electronic device configured to calculate a comparative beat frequency, the comparison pulsation frequency is close to the value of the pulsation frequency of the pulsation signal during the check data period; the comparative beat frequency is calculated using beat frequencies of the beat signal from a plurality of different data periods of interest. Including, the system.

12. 12. The system of claim 11, wherein the comparative beat frequency is calculated such that when the distance and / or line of sight velocity between the LIDAR system and an object located within the sample area during the target data period matches the distance and / or line of sight velocity between the LIDAR system and the object during the check data period, the comparative beat frequency value matches the beat frequency during the check data period.

13. The system of claim 11 , wherein the electronics is configured to compare the comparison beat frequency value with the beat frequency value of the beat signal during the check data period.

14. 14. The system of claim 13, wherein the electronics are configured to determine whether the comparison beat frequency is within a range of values, The range of values ​​includes values ​​of the beat frequency of the beat signal during the check data period.

15. calculating candidate LIDAR data from the pulsatile frequencies of the pulsatile signals from a plurality of different data periods of interest, the candidate LIDAR data indicating a potential radial velocity and / or a potential distance between the LIDAR system and an object within a sample volume; and classifying the candidate LIDAR data such that the candidate LIDAR data does not represent LIDAR data for a sample area, the LIDAR data for the sample area being indicative of a line-of-sight velocity and / or a distance between the LIDAR system and an object within the sample area; The system of claim 14 further comprising:

16. calculating candidate LIDAR data from the pulsatile frequencies of the pulsatile signals from a plurality of different data periods of interest, the candidate LIDAR data indicating a potential radial velocity and / or a potential distance between the LIDAR system and an object within a sample volume; and classifying the candidate LIDAR data such that the candidate LIDAR data represents LIDAR data for a sample area, the LIDAR data for the sample area being indicative of a line-of-sight velocity and / or a distance between the LIDAR system and an object within the sample area; The system of claim 14 further comprising:

17. 12. The system of claim 11 , wherein the electronics are configured to calculate LIDAR data from the pulsatile frequencies of the pulsatile signals obtained from a plurality of different data periods of interest, the LIDAR data indicating a radial velocity and / or a distance between the LIDAR system and an object within a sample volume.

18. The system of claim 11 , wherein the calculation of the LIDAR data excludes a pulsatile frequency of the pulsatile signal during the check data period.

19. the sample area is one of a plurality of different sample areas sequentially illuminated by the system output signal; the electronics are configured to calculate the comparative beating frequency for each sample area and to calculate the candidate LIDAR data for each different sample area, the candidate LIDAR data for each sample area being calculated from beating frequencies resulting from illumination of the sample area during a plurality of different data periods; the candidate LIDAR data for each sample area indicates a potential radial velocity and / or a potential distance between the LIDAR system and an object in the sample area; the LIDAR data for each sample area indicates a line-of-sight velocity and / or a distance between the LIDAR system and an object within the sample area; the electronics applying one or more check criteria to each comparison beat frequency; configured to provide a first result in response to applying the one or more check criteria to the comparative beat frequencies of each sample area in the first portion of the sample area, and to classify the candidate LIDAR data for each sample area in the first portion of the sample area such that the candidate LIDAR data for the sample area in the first portion of the sample area is representative of LIDAR data for the sample area in the first portion of the sample area; Also configured to provide a second result in response to application of the one or more check criteria to the comparative beating frequencies of each sample area in the second portion of the sample area, and to classify the candidate LIDAR data for each sample area in the second portion of the sample area such that the candidate LIDAR data for the sample area in the second portion of the sample area is not representative of LIDAR data for the sample area in the second portion of the sample area. The system of claim 11.

20. The system of claim 11 , wherein a rate of change of the frequency of the system output signal during the check data period is different from a rate of change of the frequency of the system output signal during the portion of the target data period.

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