Data resolution in LIDAR systems

Abstract

Data resolution in LIDAR systems Operating a LIDAR system includes transmitting a system output signal from the LIDAR system such that a sample area is illuminated by the system output signal. Different portions of the system output signal are transmitted during different data periods. The method also includes combining light returning from the system output signal to the LIDAR system with light from a reference signal to generate pulsating signals, each associated with one of the different data periods. A set of multiple candidate frequencies is generated for each of the data periods. Each of the candidate frequencies for a data period represents a potential pulsating frequency for the pulsating signal associated with the data period. The method further includes using the candidate frequencies for a check data period to identify which of the candidate frequencies for a target data period is the pulsating frequency for the pulsating signal associated with the target data period.

Description

Related Applications

[0001] This application is a continuation of U.S. Patent Application No. 18 / 119,274, filed March 8, 2023, entitled "Data Resolution in LIDAR Systems," and is hereby incorporated in its entirety.

[0002] The present invention relates to imaging systems. In particular, the present invention relates to data refinement in imaging systems.

[0003] The LIDAR system outputs a system output signal that is reflected by an object external to the LIDAR system. The reflected light returns to the LIDAR system as a system return signal. The LIDAR system combines light from the system return signal with a reference signal from a local oscillator to generate a pulsating signal. The LIDAR system includes electronics that use the pulsating frequency of the pulsating 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] Identifying the value of the beat frequency for a real beat signal can be difficult because there are often multiple solutions for the beat frequency. This ambiguity is often avoided by converting the beat signal from its real form to a complex form that combines an in-phase representation of the beat signal and its quadrature signal. Because the beat signal is represented by two different signals, multiple analog-to-digital converters (ADCs) are often required to process these complex signals. However, analog-to-digital converters (ADCs) are expensive and increase the complexity of LIDAR systems. Therefore, there is a need for a LIDAR system with reduced cost and complexity. Overview

[0005] Operation of a LIDAR system includes transmitting a system output signal from the LIDAR system such that a sample area is illuminated by the system output signal. Different portions of the system output signal are transmitted during different data periods. Light returning from the system output signal to the LIDAR system is combined with light from a reference signal to generate pulsating signals, each associated with a different data period. A set of multiple candidate frequencies is generated for each of the data periods. Each of the candidate frequencies for a data period represents a potential pulsating frequency for the pulsating signal associated with that data period. The candidate frequencies for a target data period are used to identify which of the candidate frequencies for the target data period is the pulsating frequency for the pulsating signal associated with the target data period.

[0006] Operation of a LIDAR system includes transmitting a system output signal from the LIDAR system such that a sample region is illuminated by the system output signal. The target portion of the system output signal is transmitted during a target data period. The check portion of the system output signal is transmitted during a check data period. The frequency of the system output signal changes at different rates during the target data period and the check data period. Light returning to the LIDAR system from the target portion of the system output signal is combined with light from a target reference signal to generate a target pulsating signal beating at the target pulsating frequency. Light returning to the LIDAR system from the check portion of the system output signal is combined with light from a check reference signal to generate a check pulsating signal beating at the check pulsating frequency. A plurality of candidate target frequencies are identified, including a target target frequency at the target pulsating frequency and a target image frequency at the additive inverse of the target pulsating frequency. A plurality of candidate check frequencies are identified, including a target check frequency at the target check beat frequency and a target check image frequency at the additive inverse of the target check beat frequency, and the candidate check frequencies are used to identify which of the candidate target frequencies is the target frequency.

[0007] The LIDAR system is configured to transmit a system output signal such that a sample region is illuminated by the system output signal. The target portion of the system output signal is transmitted during a target data period. The check portion of the system output signal is transmitted during a check data period. The frequency of the system output signal varies at different rates during the target data period and the check data period. The LIDAR system includes an optical coupler that combines light returning from the target portion of the system output signal to the LIDAR system with light from a target reference signal to generate a target pulsating signal pulsating at the target pulsating frequency. The optical coupler combines light returning from the check portion of the system output signal to the LIDAR system with light from a check reference signal to generate a check pulsating signal pulsating at the check pulsating frequency. The LIDAR system includes electronics that identify a plurality of target candidate frequencies and a plurality of check candidate frequencies. The plurality of target candidate frequencies include a target frequency at the target pulsating frequency and a target image frequency at the additive inverse of the target pulsating frequency. The plurality of candidate check frequencies includes a target check frequency at the check beat frequency and a check image frequency at the additive inverse of the check beat frequency, and the electronics is configured to use the candidate check frequencies to identify which of the candidate target frequencies is the target frequency.

[0008] The system operations include transmitting a system output signal from a LIDAR system such that a sample area is illuminated by the system output signal. A plurality of different candidate LIDAR data results are calculated for the sample area. Each of the different candidate LIDAR data results is a candidate for a radial velocity and / or a distance between the LIDAR system and an object within the sample area. Candidate LIDAR data results that represent valid LIDAR data for the sample area are identified.

[0009] Operating a LIDAR system includes transmitting a system output signal from the LIDAR system such that a sample area is illuminated by the system output signal. A first target portion of the system output signal is transmitted during a first target data period. A second target portion of the system output signal is transmitted during a second target data period. A check portion of the system output signal is transmitted during a check data period. The frequency of the system output signal varies at different rates during the first target data period and the second target data period. Light returning to the LIDAR system from the first target portion of the system output signal is combined with light from a first reference signal to generate a pulsating signal of the first target beating at the pulsating frequency of the first target. Light returning to the LIDAR system from the second portion of the system output signal is combined with light from a second reference signal to generate a pulsating signal of the second target beating at the pulsating frequency of the second target. Light returning to the LIDAR system from the check portion of the system output signal is combined with light from a check reference signal to generate a check pulsating signal pulsating at a check pulsating frequency. A plurality of first target candidate frequencies are identified. The first target candidate frequencies include a first target frequency at the first target pulsating frequency and a first image frequency at the additive inverse of the first target pulsating frequency. A plurality of second target candidate frequencies are identified. The second target candidate frequencies include a second target frequency at the second target pulsating frequency and a second image frequency at the additive inverse of the second pulsating frequency. A plurality of check candidate frequencies are identified. The check candidate frequencies include a check target frequency at the check pulsating frequency and a check image frequency at the additive inverse of the check pulsating frequency. A plurality of candidate frequency pairs are identified. Each candidate frequency pair includes one of the first target candidate frequencies and one of the second target candidate frequencies. A candidate LIDAR data result is calculated for each of the candidate frequency pairs, the candidate LIDAR data result for each candidate frequency pair being calculated from a first target frequency and a second target frequency of the candidate frequency pair.Candidate LIDAR data results for each candidate frequency pair are candidates for radial velocity and / or distance between the LIDAR system and an object within the sample volume. Candidate LIDAR data results calculated from the first target frequency and the second target frequency are identified.

[0010] The system includes a LIDAR system configured to transmit a system output signal such that a sample region is illuminated by the system output signal. A first target portion of the system output signal is transmitted during a first target data period. A second target portion of the system output signal is transmitted during a second target data period. A check portion of the system output signal is transmitted during a check data period. The frequency of the system output signal varies at different rates during the first target data period and the second target data period. An optical signal combiner combines light returning from the first target portion of the system output signal to the LIDAR system with light from the first target portion of the reference signal to generate a pulsating signal of the first target beating at the pulsating frequency of the first target. The optical signal combiner also combines light returning from the second target portion of the system output signal to the LIDAR system with light from the second target portion of the reference signal to generate a pulsating signal of the second target beating at the pulsating frequency of the second target. The optical signal combiner combines light returning to the LIDAR system from the check portion of the system output signal with light from the check portion of the reference signal to generate a check pulsating signal pulsating at a check pulsating frequency. The electronics identify a plurality of first candidate frequencies, a plurality of second candidate frequencies, and a plurality of check candidate frequencies. The first candidate frequencies include a first target frequency at a first subject's pulsating frequency and a first image frequency at an additive inverse of the first subject's pulsating frequency. The second candidate frequencies include a second target frequency at a second pulsating frequency and a second image frequency at an additive inverse of the second pulsating frequency. The third candidate frequencies include a third target frequency at a third pulsating frequency and a third image frequency at an additive inverse of the third pulsating frequency. The electronics identify a plurality of candidate frequency pairs and calculate candidate LIDAR data results from each of these candidate frequency pairs. Each candidate frequency pair includes one of the first candidate frequencies paired with one of the second candidate frequencies. The candidate LIDAR data results for each candidate frequency pair provide a candidate radial velocity and / or distance between the LIDAR system and an object within the sample volume.The electronics identify which of the candidate LIDAR data results are calculated from the first target frequency and the second target frequency, and the identified candidate LIDAR data results can serve as valid LIDAR data for the sample area. [Brief explanation of the drawings]

[0011] 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.

[0012] 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.

[0013] 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.

[0014] FIG. 2 is a top view of an example of a LIDAR adapter suitable for use with the LIDAR chip of FIG. 1B.

[0015] FIG. 3 is a top view of an example of a LIDAR adapter suitable for use with the LIDAR chip of FIG. 1C.

[0016] 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.

[0017] FIG. 5A illustrates an example of a processing unit suitable for use with a LIDAR system.

[0018] FIG. 5B shows a schematic of electronics suitable for use with a processing unit constructed according to FIG. 5A.

[0019] FIG. 5C is a graph of frequency versus time of the system output signal.

[0020] FIG. 5D shows a frequency spectrum with frequency peaks corresponding to +f and f.

[0021] FIG. 5E shows a frequency spectrum with corresponding pairs of frequency peaks each resulting from the presence of different objects in the sample area within the field of view of the LIDAR system.

[0022] Figure 6 shows a flow diagram of the LIDAR data refinement process.

[0023] Figure 7 shows a cross-sectional view of a portion of a LIDAR chip with a waveguide on a silicon-on-insulator platform.

[0024] The LIDAR system transmits a system output signal from the LIDAR system such that a sample area is illuminated by the system output signal. Different portions of the system output signal are transmitted during different data periods. Light returning from the system output signal to the LIDAR system is combined with light from a reference signal to generate pulsating signals, each associated with a different data period. A set of multiple candidate frequencies is calculated for each of the data periods. Each of the candidate frequencies for a data period represents a potential pulsating frequency of the pulsating signal associated with that data period. The candidate frequencies for the check data period are used to identify which of the candidate frequencies for a target data period is the correct pulsating frequency of the pulsating signal associated with the target data period. LIDAR data for the sample area is calculated from the candidate frequencies identified as the correct pulsating frequency of the pulsating signal.

[0025] The existence of multiple frequencies that are candidates for the actual beat frequency can be a result of processing the real form of the beat signal rather than the complex form. Because the real form of the beat signal does not contain the quadrature components of the beat signal, multiple analog-to-digital converters (ADCs) required to process the complex form of the beat signal can be replaced with a single ADC. As a result, the cost and complexity of the LIDAR system are reduced.

[0026] 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 other than the LIDAR chip. The LIDAR chip may include an integrated photonic circuit (PIC) or may be an integrated photonic circuit chip. The LIDAR chip includes a light source 4 that outputs a preliminary output 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).

[0027] The LIDAR chip includes a utility waveguide 12 that receives an outgoing LIDAR signal from a light source 4. The utility waveguide 12 terminates in a facet 14 to transmit 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, the facet 14 can be positioned at the end of the chip, such that 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 exit for the LIDAR output signal from the LIDAR chip is also the exit for the LIDAR output signal from the LIDAR system, then the LIDAR output signal can also be considered a system output signal.

[0028] 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 in the path of the LIDAR output signal. When the LIDAR output signal is reflected, at least a portion of the reflected light returns toward the LIDAR chip as a LIDAR input signal. In some cases, the LIDAR input signal may also be considered a system return signal. For example, if the exit for the LIDAR output signal from the LIDAR chip is also the exit for the LIDAR output signal from the LIDAR system, the LIDAR input signal may also be considered a system return signal.

[0029] The LIDAR input signal may be incident on utility waveguide 12 through facet 14. The 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, which moves 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 illustrates a directional coupler operating as splitter 16, other signal tapping devices may 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.

[0030] The utility waveguide 12 transmits the outgoing LIDAR signal to a splitter 16. The splitter 16 transfers a portion of the outgoing LIDAR signal from the utility waveguide 12 to a reference waveguide 20 as a reference signal. The reference waveguide 20 transmits the reference signal to a processing unit 22 for further processing.

[0031] The fraction of light redirected from the utility waveguide 12 by the splitter 16 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. Many splitters 16, such as directional couplers or multimode interferometers (MMIs), have the outgoing fraction 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 provide outgoing and incoming fractions that are at or about 50%. However, a multimode interferometer (MMI) may be 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) and the output / input fractions are 50% or substantially 50%. 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 in the field of view. This composite signal can then be processed to extract LIDAR data for the sample area, such as radial velocity and / or distance between the LIDAR system and an object external to the LIDAR system.

[0032] 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 moves 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 illustrates a directional coupler operating 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.

[0033] 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.

[0034] The LIDAR system can be modified so that the incoming LIDAR signal and outgoing LIDAR signal are transmitted through different waveguides. For example, FIG. 1B is a top view of the LIDAR chip of FIG. 1A modified so that the incoming LIDAR signal and outgoing LIDAR signal 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 a first LIDAR input signal. The first LIDAR input signal enters comparison waveguide 18 through facet 35 and serves as a 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 the reference signal to processing unit 22 for further processing. As will be explained in more detail below, processing unit 22 combines the comparison signal with the reference signal to generate a composite signal conveying LIDAR data for the sample area within the field of view.

[0035] The LIDAR chip can be modified to receive multiple LIDAR input signals. For example, FIG. 1C shows 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).

[0036] The outgoing LIDAR signal exits the LIDAR chip through facet 14 and serves as the LIDAR output signal. When light from the LIDAR outgoing 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.

[0037] 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 second comparison waveguide 50 through facet 52 and serves as a second comparison signal transmitted by second comparison waveguide 50. Second comparison waveguide 50 transmits the second comparison signal to second processing unit 48 for further processing.

[0038] 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 the outgoing LIDAR signal to enter utility waveguide 12 from light source 4 located off the LIDAR chip.

[0039] In some cases, a LIDAR chip constructed according to Figure 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 a field of view, such that the optical paths along which a first LIDAR input signal and / or a LIDAR output signal travel from the LIDAR chip to the field of view pass through the LIDAR adapter. The LIDAR adapter can also 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 on the same optical path between the LIDAR adapter and a reflective object in the field of view.

[0040] An example of a LIDAR adapter suitable for use with 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, such 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.

[0041] 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 such that the LIDAR output signal is traveling toward a sample area within a field of view. Thus, in some cases, the portion of the LIDAR output signal that exits the LIDAR adapter can also be considered a system output signal. For example, if the LIDAR output signal exit from the LIDAR adapter is also the exit for the LIDAR output signal from the LIDAR system, the LIDAR output signal can also be considered a system output signal.

[0042] 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.

[0043] 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. This 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.

[0044] 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 a 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.

[0045] 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 can be operated by the electronics 32, thereby allowing the electronics 32 to control the power of the LIDAR output signal.

[0046] 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 can be 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 can be 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 waveguide 18.

[0047] The LIDAR adapter may also include one or more redirecting elements, such as mirrors. Figure 2 illustrates 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.

[0048] 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.

[0049] 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.

[0050] The LIDAR system 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 returned light. Thus, the system return signal can contain light of different linear polarization states. For example, a first portion of the system return signal can contain light of a first linear polarization state, and a second portion of the system return signal can contain light of 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 the angle is 90 degrees, LIDAR data may be lost in the resulting composite signal. However, the LIDAR system can be modified to compensate for changes in the polarization state of the LIDAR output signal.

[0051] 3 illustrates the LIDAR system of FIG. 3 with a modified LIDAR adapter suitable for use with the LIDAR chip of FIG. 1C. The LIDAR adapter includes a beam splitter 120 that receives a system return signal from the circulator 100. The beam splitter 120 splits the system return signal into a first portion of the system return signal and a second portion of the system return signal. Suitable beam splitters include, but are not limited to, a Wollaston prism or a MEMS-based beam splitter.

[0052] 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 connection with 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.

[0053] The beam splitter 120 may be a polarizing beam splitter. An 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 may be linearly polarized such that the LIDAR output signal has a first polarization state. Suitable beam splitters include, but are not limited to, a Wollaston prism or a MEMS-based polarizing beam splitter.

[0054] A 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 a second polarization state to a first polarization state. As a result, the second LIDAR input signal has the first polarization state but does not have, or is substantially free of, the second polarization state. Thus, the first LIDAR input signal and the second LIDAR input signal each have the same polarization state (the first polarization state in this example). 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 as a result of the use of a polarizing beam splitter. For example, the first LIDAR input signal transmits reflected light with a first polarization state, and the second LIDAR input signal transmits reflected light with a second polarization state. As a result, the first LIDAR input signal is associated with a first polarization state and the second LIDAR input signal is associated with a second polarization state.

[0055] Because the first LIDAR input signal and the second LIDAR input signal transmit light of 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.

[0056] Suitable polarization rotators include, but are not limited to, polarization-maintaining fiber rotation, Faraday rotators, half-wave plates, MEMS-based polarization rotators, integrated optic polarization rotators using asymmetric Y-junctions, Mach-Zehnder interferometers, and multimode interference couplers.

[0057] 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, second reference signal, comparison signal, and second comparison signal each have the same polarization state. In the example disclosed in the context of FIG. 3, the first comparison signal, second comparison signal, first reference signal, and second reference signal can each have light of a first polarization state.

[0058] 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 is the result of combining the first reference signal and the first comparison signal in a first polarization state, excluding or substantially excluding light in a second polarization state. Alternatively, the composite signal is the result of combining the first reference signal and the first comparison signal in a second polarization state, excluding or substantially excluding light in the first polarization state. Similarly, the second composite signal includes the second reference signal and the 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 is the result of combining the second reference signal and the second comparison signal in a first polarization state, excluding or substantially excluding light in the second polarization state. Alternatively, the second composite signal is the result of 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.

[0059] With the above configuration, LIDAR data for a single sample area within a 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 electronics combining LIDAR data from the different composite signals (i.e., a first composite signal and a 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.

[0060] In some cases, measuring LIDAR data for the sample area includes electronics identifying one or more composite signals (i.e., the composite signal and / or the second composite signal) as sources of LIDAR data that most closely represent reality (representative LIDAR data). The electronics can then 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 a signal with representative LIDAR data and use the LIDAR data from the identified signal for further processing by the LIDAR system. In some cases, the electronics can combine identifying 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 a signal with representative LIDAR data, and if two or more composite signals are identified as signals with 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 may use the LIDAR data from that composite signal as the representative LIDAR data. If none of the composite signals are identified as having representative LIDAR data, the electronics may discard the LIDAR data for the sample regions associated with those composite signals.

[0061] While Figure 3 is described in the context of components being 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 components in Figure 3 can be arranged such that the composite signal is the result of combining the reference signal and the comparison signal with the same linear polarization state, and the second composite signal is the result of combining the reference signal and the comparison signal with the same linear polarization state. For example, beamsplitter 120 can be configured such that a second portion of the system return signal has a first polarization state and a 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.

[0062] The above system configuration directs the first portion of the system return signal and the second portion of the system return signal into different composite signals, each associated with a different polarization state, such that 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.

[0063] 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 focuses or collimates 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 redirectors 124, such as a mirror or a prism. FIG. 3 illustrates a LIDAR adapter including a mirror as the redirector 124, which redirects a second portion of the system return signal from the circulator 100 to the facet 52 of the second comparison waveguide 50 and / or the third lens 126.

[0064] When the 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 on a common support 140. While the electronics 32 is shown disposed on the common support, all or a portion of the electronics can be disposed remotely from the common support. When the light source 4 is disposed remotely from the LIDAR chip, the light source can be disposed on the common support 140 or remotely from the common support 140. Suitable methods for attaching the LIDAR chip, electronics, and / or LIDAR adapter to the common support include, but are not limited to, epoxy, solder, and mechanical clamps.

[0065] The LIDAR system may include components including additional passive and / or active optical components. For example, the LIDAR system may include one or more components that receive the LIDAR output signal from the LIDAR chip or from the LIDAR adapter. A portion of the LIDAR output signal from the one or more components may function as the system output signal. For example, the LIDAR system may include one or more beam steering units that receive the LIDAR output signal from the LIDAR chip or from the LIDAR adapter and output all or a portion of the LIDAR output signal that functions as the system output signal. For example, FIG. 4 illustrates a beam steering unit 142 that receives the LIDAR output signal from the 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 components include, but are not limited to, movable mirrors, MEMS mirrors, optical phased arrays (OPAs), and actuators that move the LIDAR chip, LIDAR adapter, and / or common support.

[0066] The electronics can operate one or more beam steering units 142 to steer the stem output signal to different sample areas 144. The sample areas can extend up to a maximum distance away from the LIDAR system 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 the LIDAR system can include or consist of the space occupied by a combination of the sample areas.

[0067] 5A-5C illustrate 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 comparison waveguide 196 and a reference signal from reference waveguide 198. Comparison waveguide 18 and reference waveguide 20 shown in FIGS. 1A and 1B can function as comparison waveguide 196 and reference waveguide 198, comparison waveguide 18 and first reference waveguide 42 shown in FIG. 1C can function as comparison waveguide 196 and reference waveguide 198, or second comparison waveguide 50 and second reference waveguide 44 shown in FIG. 1C can function as comparison waveguide 196 and reference waveguide 198.

[0068] Comparison waveguide 196 transmits the comparison signal to optical signal combiner 211. Reference waveguide 198 transmits the reference signal to optical signal combiner 211. First optical signal combiner 211 combines the comparison signal with the reference signal to generate a first composite signal. Due to the frequency difference between the comparison signal and the reference signal, the first composite signal pulsates between the comparison signal and the reference signal.

[0069] The first optical signal 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 a 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 a second portion of the second composite signal into a second electrical signal. Examples of suitable optical sensors include a germanium photodiode (PD) or an avalanche photodiode (APD).

[0070] In some cases, the optical signal combiner 211 splits the first composite signal such that the portion of the comparison signal included in the first portion of the composite signal is phase-shifted 180 degrees relative to the portion of the comparison signal in the second portion of the composite signal, but the portion of the reference signal in the first portion of the composite signal is not phase-shifted relative to the portion of the reference signal in the second portion of the composite signal. Alternatively, the optical signal combiner 211 splits the composite signal such that the portion of the reference signal in the first portion of the composite signal is phase-shifted 180 degrees relative to the portion of the reference signal in the second portion of the composite signal, but the portion of the comparison signal in the first portion of the composite signal is not phase-shifted relative to the portion of the comparison signal in the second portion of the composite signal.

[0071] The first optical sensor 223 and the second optical sensor 224 can 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, and the second optical sensor 224. Although a photodiode symbol is used to represent the first optical sensor 223 and the second optical sensor 224, one or more of these sensors can 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 outside the LIDAR chip.

[0072] The electronics connects a first photosensor 223 and a second photosensor 224 as a first balanced detector 225. Specifically, the first photosensor 223 and the second photosensor 224 are connected in series. The series connection in the first balanced detector communicates with a first data line 228, which carries the output of the first balanced detector as a first data signal. The first data signal is an electrical representation of the first composite signal. Thus, the first data signal includes contributions from a first waveform and a second waveform. The first data signal pulses as a result of the pulse between the comparison signal and the reference signal. Other photodetectors can be used in place of the balanced detector. For example, a single photodiode can replace the balanced detector.

[0073] The electronics 32 includes a transform mechanism 238 configured to perform a mathematical transform on the first data signal. For example, the mathematical transform may be a real Fourier transform, with the first data signal as a real input. Because this transform operates on real signals rather than complex signals, the first data signal may be an electrical in-phase representation of the composite signal and may exclude quadrature signals.

[0074] 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, which is a digital representation of the first data signal.

[0075] The conversion mechanism 238 includes a converter 268 that receives a first data signal as an input from a first analog-to-digital converter (ADC) 264. The converter 268 can be configured to perform a mathematical transform on the first data signal to convert it from the time domain to the frequency domain. The mathematical transform can be a real transform, such as a real Fast Fourier Transform (FFT). A real transform, such as a real Fast Fourier Transform (FFT), provides an output having one or more frequency peaks. The electronics use the one or more frequency peaks output from the converter 268 to generate LIDAR data (range and / or radial velocity between the reflecting object and the LIDAR chip or LIDAR system) for further processing. The converter 268 can perform its designated function using firmware, hardware, software, or a combination thereof.

[0076] The electronics 32 includes a peak detector 270 that receives the output from the transducer 268. The peak detector 270 is configured to detect peaks from the output of the transducer 268 to identify the beating frequencies of the composite optical signal. In some cases, the peak detector is configured so that each identified peak frequency has an amplitude above a selected threshold to reduce noise and / or prevent spurious peak frequencies. In some cases, the peak detector 270 can store the peak frequencies in memory 271 for later use by a LIDAR data generator 274. The LIDAR data generator 274 uses the peak frequencies to generate LIDAR data (such as the distance and / or line-of-sight velocity between the 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.

[0077] 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 a cycle.

[0078] Figure 5C shows the 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, the frequency versus time pattern is repeated for each cycle, as shown in FIG. 5C. The illustrated cycles do not include rearrangement periods and / or no rearrangement periods are interspersed between cycles. As a result, FIG. 5C shows the results of a continuous scan.

[0079] Each cycle is associated with a period index m, andm It contains M data periods, denoted as M. Suitable values ​​for M are M > 2. In the example of Figure 5C, M=3. As a result, in each cycle, m , where m=1, 2, and 3. In some cases, the frequency versus time pattern is the same for corresponding data periods in different cycles, as shown in FIG. 5C. 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 pattern is the same in FIG. 5C. At the end of a cycle, the electronics returns the frequency to the same frequency level as at the start of the previous cycle.

[0080] Data Period DP m During this period, the electronics may operate the light source such that the frequency of the system output signal varies linearly as a function of time. For example, during a data period DP m wherein the frequency of the system output signal is varied at a constant or substantially constant rate α m The chirp rate may vary at a constant rate (chirp rate) over the entire data period. The chirp rate may continue for all or part of a data period. For example, during a data period labeled DP1, the electronics operate a light source such that the frequency of the system output signal varies at a linear rate α1; during a data period labeled DP2, the electronics operate a light source such that the frequency of the system output signal varies at a linear rate α2; and during a data period labeled DP3, the electronics operate a light source such that the frequency of the system output signal varies at a linear rate α3.

[0081] 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 can function as the target sample area, and DP3 associated with the sample area can function as the check data period. Data period m(α m) the rate of change of the frequency of the system output signal may vary for each data period of interest. In some cases, M α1 to α so that the sum is zero M are selected. For example, when M is 3, α1, α2, and α3 are selected so that 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, or α3 = 0. In some cases, the rate of change of the frequency of the system output signal during the check data period is not zero.

[0082] Different portions of the system output signal are transmitted from the LIDAR system during different data periods. For example, a first target portion of the system output signal can be transmitted during a first target data period (m=1 in the example of FIG. 5C). A second target portion of the system output signal can be transmitted during a second target data period (m=2 in the example of FIG. 5C). A check portion of the system output signal can be transmitted during a check data period (m=2 in the example of FIG. 5C). Different portions of the system output signal can be combined with different portions of the reference signal to generate a composite signal pulsating at a pulsating frequency. For example, light returning to a LIDAR system from a first target portion of the system output signal can be combined with light from a first target portion of a reference signal to generate a pulsating signal of the first target pulsating at the pulsating frequency of the first target. Light returning to a LIDAR system from a second target portion of the system output signal can be combined with light from a second target portion of a reference signal to generate a pulsating signal of the second target pulsating at the pulsating frequency of the second target. Light returning to the LIDAR system from the check portion of the system output signal can be combined with light from the check portion of the reference signal to generate a check beat signal that beats at a check beat frequency.

[0083] While Figure 5C illustrates two target data periods, a sample area can 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, or alternatively, one target data period. The rate of change of the system output signal frequency during the check data period may be different from the rate of change of the system output signal frequency for all or part of the target data period. Thus, the rate of change of the system output signal frequency during each data period associated with the same sample area may be different.

[0084] The frequency of the system output signal can be increased during one data period of interest associated with a sample region, as evident from data period DP1 in Figure 5C. The pulsation frequency of the composite signal during the data period of interest (increasing data period) during which the frequency of the system output signal is increased is f ub The rate of increase is α ub As a result, in the example of FIG. 5C, f1= f ub , and α1= α ub The frequency of the system output signal can decrease during a data period of interest associated with the same sample region, as evident from data period DP2 in FIG. 5C. The beat frequency of the composite signal during the data period in which the frequency of the system output signal decreases is f db The rate of decrease can be expressed as α db As a result, in the example of FIG. 5C, f2 = f db , and α2 = α db This becomes:

[0085] Figure 5C shows the SR associated with the sample region index k. k The sample area is labeled as SR. k From SR k+1 Each sample area is illuminated with a system output signal during the data period that FIG. 5C shows as associated with that sample area. For example, sample area SRk+1 is a cycle j+1 The system is illuminated with the system output signal during the data periods denoted as DP1, DP2, and DP3. k+1 The sample area marked with is the cycle j+1 , associated with data periods denoted DP1 to DP3. A sample area index k can be assigned with respect to time. For example, the sample areas can be illuminated in the order indicated by the index k by the system output signal. As a result, sample areas SR 10 is after sample area SR9 and SR 11 Although Figure 5C illustrates a single sample area being illuminated during one cycle, multiple different sample areas can be illuminated during one cycle.

[0086] Each object illuminated by the system output signal produces a set of frequency peaks in the frequency spectrum. For example, a real Fourier transform of a composite signal can output multiple different peak frequencies, each separated by the same amount from the DC frequency. As an example, FIG. 5D shows an example of a frequency spectrum that can be output from a mathematical transform. The frequency spectrum shows power versus frequency. The frequency spectrum illustrates a frequency peak at +f relative to the DC frequency and another corresponding frequency peak at -f relative to the DC frequency. One of these frequency peaks is at the beat frequency of the composite signal and serves as the target beat frequency. One of these frequency peaks is at the additive inverse of the beat frequency of the composite signal and serves as the image beat frequency. It is often unclear which of the beat frequencies represents the target beat frequency and which of the beat frequencies represents the image beat frequency. As described below, the beat frequency during one of the check data periods in each cycle can be used to identify which frequency peak represents the target beat frequency.

[0087] If multiple different objects are present in the sample volume, the peak detector can output a set of multiple frequency peaks, each associated with one of the different objects. As a result, the frequency spectrum can include multiple target beat frequencies and multiple image beat frequencies. Each peak frequency output from the peak detector can be a candidate for the target beat frequency. The candidate frequencies are f m,n where m represents the period index and n represents the index of the frequency peak within data period m. As an example, FIG. 5E illustrates a potential frequency spectrum. The frequency spectrum is expressed as f m,1 , f m,2、 f m,3 , and f m,4 There are four frequency peaks at f m,1 and f m,2 The frequency peaks at are the corresponding frequency peaks at f m,3 and f m,4 The frequency peaks at are the corresponding frequency peaks.

[0088] Candidate frequency (f m,nAs is evident from the period index m in data period m, if one or more objects are present within the illuminated sample region during data period m, each data period is associated with a set of candidate frequencies including at least one target beat frequency and at least one image beat frequency. For example, if the system output signal has a frequency versus time pattern according to FIG. 5C , a first-object data period (m = 1) can be associated with a plurality of first-object candidate frequencies including a first-object target frequency at the first-object beat frequency and a first-object image frequency at the additive inverse of the first-object beat frequency. A second-object data period (m = 2) can be associated with a plurality of second-object candidate frequencies including a second-object target frequency at the second-object beat frequency and a second-object image frequency at the additive inverse of the second-object beat frequency. A check data period (m = 3) can be associated with a plurality of check candidate frequencies including a check target frequency at the check beat frequency and a check image frequency at the additive inverse of the check beat frequency.

[0089] The number of candidate frequencies occurring in data period m (i.e., f in Figure 5E) m,1 , f m,2 , f m,3 , and f m,4 ) is the number of objects that can exist in the sample area (N in Figure 5E). o = 2). Candidate frequencies from different data periods of interest can be grouped into candidate frequency pairs. o )) 2 There may be N candidate frequency pairs, where N o represents the number of objects likely to be within the sample region as indicated by the output of the peak detector. Each candidate frequency pair includes candidate frequencies from two different data periods of interest. For example, for data period of interest m=1, the candidate frequencies are f 1,1 , f 1,2 , f 1,3 , and f 1,4 If so, then in the target data period m=2, the candidate frequency is f 2,1 , f 2,2, f 2,3 , and f 2,4 Become;N o = 2, and (f 1,1 , f 2,1 ), (f 1,1 , f 2,2 ), (f 1,1 , f 2,3 ), (f 1,1 , f 2,4 ), (f 1,2 , f 2,1 ), (f 1,2 , f 2,2 ), (f 1,2 , f 2,3 ), (f 1,2 , f 2,4 ), (f 1,3 , f 2,1 ), (f 1,3 , f 2,2 ), (f 1,3 , f 2,3 ), (f 1,3 , f 2,4 ), (f 1,4 , f 2,1 ), (f 1,4 , f 2,2 ), (f 1,4 , f 2,3 ), and (f 1,4 , f 2,4 ) there are 16 candidate frequency pairs. Each of the candidate frequency pairs can be associated with a pair index i′. For example, each of the candidate frequency pairs can be associated with a pair index i′. i’ where i' ranges from 1 to (2(N o )) 2 As an example, the candidate frequency pair above has values ​​P1=(f 1,1 , f 2,1 ) to P I’ = (f 1,1, f 2,1 ), where I' = (2(N o )) 2Each candidate frequency pair can be a pair of the correct beat frequency generated by an object during data period m=1 and the correct beat frequency generated by the same object during data period m=2. Therefore, there are N valid candidate frequency pairs, each of which can serve as a valid frequency pair. o There are pieces.

[0090] Beat frequencies from two or more different data periods associated with the same sample area can be combined to generate LIDAR data for that sample area. For example, sample area SR k The pulsation frequency measured from DP1 during irradiation of the sample area SR k Combined with the beating frequency 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 beat frequency in is given by Equation 1: f m = 2α m It can be expressed as R / c-2υ / λ, where m represents the period 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.

[0091] The above formula 1:(f m = 2α m In the equation (R / c-2v / λ), the values ​​of v 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 v and R for that sample area. 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 )) and 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 fdb ) / (2(α ub -α db is obtained.

[0092] 5B, the electronics include a LIDAR data generator 274 that receives the beat frequencies from memory 271 and / or peak detector 270. LIDAR data generator 274 can calculate LIDAR data for each candidate frequency pair using Equations 2 and 3. For example, if the system output signal has a frequency versus time pattern according to FIG. 5C, then f 1,n The value of (m=1) is f in Equation 2 and / or Equation 3. ub and f 2,n The value of (m=1) is f in Equation 2 and / or Equation 3. db As a result, the LIDAR data generator 274 can calculate a candidate range and / or a candidate radial velocity (R and / or υ) for each candidate frequency pair. As a result, for each candidate frequency pair (P i’ ) is the candidate distance (R i’ ) and / or candidate radial velocity (υ i’ ) associated with the candidate distance and / or candidate radial velocity (R i’ and / or υ i’ ) can represent candidate LIDAR data for a sample area. The candidate LIDAR data can potentially be represented by f ub , f db , and f chk The LIDAR data generator 274 may use firmware, hardware, software, or a combination thereof to perform its specified functions.

[0093] The electronics may include a LIDAR data verifier 276 that receives the candidate LIDAR data from a LIDAR data generator 274. The LIDAR data verifier 276 may select a period peak frequency (f) for checking from memory 271 and / or peak detector 270.chk,n ) can also be received. If the system output signal has a frequency versus time pattern according to FIG. 5C, the data period denoted as DP3 can serve as a check data period. As a result, 3,n The values ​​of (m=3) are the periodic pulsation frequency (f chk,n ) can function as a two-object sample area (N o =2), the period peak frequency (f chk,1 , f chk,2 , f chk,3 , f chk,4 ) exists.

[0094] The LIDAR data validator 276 can use the checking data periods associated with a sample region to identify which of the candidate LIDAR data values ​​associated with that sample region are correct. For example, the LIDAR data validator 276 can check the candidate frequency pair P i’ From the candidate LIDAR data associated with chk,i’ ) can be calculated. chk ) is the frequency change rate α during the check data period chk Substituting into Equation 1, we get Equation 4:cf chk = 2α chk R / c-2v / λ. If the system output signal has a frequency versus time pattern according to FIG. 5C, the data period denoted as DP3 can serve as a check data period. As a result, the value of α3 is α chk The LIDAR data validator 276 can function as a candidate frequency pair P i’ The period beat frequency for comparison check is given by Equation 5: cf chk,i’ = 2α chk R i’ / c-2υ i’ / λ, where R i’ is the candidate frequency pair P i’represents the candidate distance for i’ is the candidate frequency pair P i’ represents the candidate radial velocity for

[0095] The LIDAR data validator 276 determines the candidate frequency pairs (cf chk,i’ ) for comparison check period beat frequency, N o valid candidate frequency pairs (valid frequency pairs) can be identified, and LIDAR data for one or more valid frequency pairs can be identified accordingly. For example, the LIDAR data validator 276 may apply one or more check criteria to each candidate frequency pair P i’ As an example, the LIDAR data validator 276 may apply 2N LIDAR images from the same sample area. o Check the period for the pulsation frequency (f chk,n ) and the period pulsation frequency (cf chk,i’ ) can be compared to identify matching values. As a more specific example, in some cases, the period beat frequency (f) calculated for each check for the sample region can be compared to identify matching values. chk,n ) is calculated for the sample area and the period beating frequency (cf chk,i' ) for each comparison check period beat frequency (cf chk,i' For example, the LIDAR data verifier 276 may use a period beat frequency (cf chk,i’ ) from each of the data periods (f chk,n ) can be subtracted to generate a match index. The number of match indexes is 2N o *(2(N o )) 2 The LIDAR data validator 276 may be configured to find the LIDAR data validator 276 that has the smallest absolute value, N o In one example, the LIDAR data validator 276 may identify match indices for i′ ranging from 1 to (2(N o )) 2All values ​​up to and including n from 1 to 2N o For all values ​​up to i’,n = |cf chk,i’ -f chk,n The LIDAR data validator 276 can calculate the value of |. o X's i’,n The results of the above can be identified as matching values. The matching values ​​are calculated based on the estimated beat frequency (cf) for the data period being checked from the data for the candidate pair. chk,i’ ) and the actual measured pulsation frequency (f chk,n ) matches. N o Each value of i' for the identified match indices is a candidate frequency pair P associated with one of the objects in the sample region. i’ For example, the LIDAR data verifier 276 may use the match index X 5,3 and X 9,1 , the candidate frequency pair associated with i'=5 and i'=9 is identified as a valid frequency pair for sample region m, i.e., P5= (f m,n , f m,n ) and P9 = (f m,n , f m,n ) Therefore, the identified candidate pair P i’ The peak frequencies in each of the candidate frequency pairs P5 = (f 1,1 , f 2,4 ) is identified, the peak frequency f 1,1 and f 2,4is identified as occurring during data periods m=1 and m=2 of interest and representing actual beat frequencies resulting from reflections of the system output signal by the same object within the sample region. Similarly, candidate LIDAR data associated with the identified i' value is also assigned and serves as the LIDAR data for sample region m. For example, the sample region may be treated as including an object at range R5 with a radial velocity of υ5 and an object at range R9 with a radial velocity of υ9. The LIDAR data verifier 276 may discard frequency pairs having pair indexes (i') associated with match indices not identified by the LIDAR data verifier 276. Similarly, the LIDAR data verifier 276 may discard LIDAR data (R i’ and / or υ i’ ) may be discarded. The LIDAR data verifier 276 may perform its specified functions using firmware, hardware, software, or a combination thereof.

[0096] Period beat frequency (cf) for comparison check chk,i’ ) are the check period pulsation frequency (f chk,n ) but is not a function of the value of the beat frequency during the check period, but is a function of the beat frequencies from the data periods of multiple different subjects. The comparison beat frequency for each candidate frequency pair represents a value that the beat frequency associated with the check data period may have if, in the candidate frequency pair, the beat frequency of the first subject is equal to the candidate frequency from the data period of the first subject, and the beat frequency of the second subject is equal to the candidate frequency from the data period of the second subject. The comparison check period beat frequency (cf chk,i’ ) are calculated from the beat frequencies during the data periods of multiple different subjects. For example, in the above example, the beat frequencies (cf chk,i’ ) is calculated from the beating frequency during the data period of the increasing target and the data period of the decreasing target. As a result, the period beating frequency (cf chk,i’) is a function of the distance (R) and the line of sight velocity (υ) during the data period other than the check data period. On the other hand, the pulsation frequency (f chk,n ) is a function of the distance (R) and the line of sight velocity (υ) values ​​during the check data period. Therefore, if the distance (R) and line of sight velocity (υ) values ​​match in both the check data period and the associated target data period, the pulsation frequency (f chk,n ) is the periodic pulsation frequency (cf chk,i’ For example, if the distance (R) and the line of sight velocity (υ) are constant or substantially constant during a check data period, an associated increase data period, and an associated decrease data period, the pulsation frequency (f chk,n ) is the period pulsation frequency (cf chk,i’ ) value. chk,i’ ) and associated candidate LIDAR data are discarded.

[0097] 6 is a flow diagram of a LIDAR data refinement process that can be used to identify valid LIDAR data. At process block 310, a sample region of interest (SR k ) is received. For example, the LIDAR data generator 274 can receive the beat frequencies from the memory 271 and / or the peak detector 270. As described above, the received beat frequencies include beat frequencies from two or more target data periods and at least one check data period. For example, if the system output signal has a frequency vs. time pattern according to FIG. 5C , the received beat frequencies are k The data periods DP1, DP2, and DP3 may include the beat frequencies obtained from the system output signal during the data periods DP1, DP2, and DP3. In some cases, DP1 and DP2 may serve as the data periods of interest, and DP3 may serve as the check data period. As another example, DP1 and DP3 may serve as the data periods of interest, and DP2 may serve as the check data period.

[0098] In process block 312, the LIDAR data generator selects candidate frequencies (f m,n ) can be identified. m,n ) set of sample regions SR k For example, if the system output signal has the frequency versus time pattern shown in FIG. 5C , a set of first candidate frequencies can be identified that includes one or more first target frequencies, each at the first subject's beat frequency, and one or more first image frequencies, each at an additive inverse of the first subject's beat frequency; a set of second candidate frequencies can be identified that includes one or more second target frequencies, each at the second subject's beat frequency, and one or more second image frequencies, each at an additive inverse of the second subject's beat frequency; and a set of check candidate frequencies can be identified that includes one or more check target frequencies, each at the check beat frequency, and one or more check image frequencies, each at an additive inverse of the check beat frequency.

[0099] Candidate frequency (f m,n To find the set of N, the peak detector 270 can search the entire frequency spectrum for frequency peaks. Alternatively, the peak detector 270 can search on the positive side of the frequency spectrum (>DC) or the negative side of the frequency spectrum. If the peak detector 270 searches on the positive side of the frequency spectrum (>DC) or the negative side of the frequency spectrum, the peak detector o As a result, the LIDAR data generator 274 generates a sample region SR k Candidate frequencies for (f m,n ) can be received. k Candidate frequencies for (f m,n ), the LIDAR data generator 274 receives only a portion of the candidate frequencies (fm,n ) and add the frequency corresponding to the sample area SR k Complete candidate frequencies (f m,n ) can be identified. When the peak detector 270 searches for frequency peaks throughout the frequency spectrum, the set of received candidate frequencies (f m,n ) is the sample area SR k Complete candidate frequencies (f m,n ) can function as a set of

[0100] In process block 314 , the LIDAR data generator 274 may identify candidate frequency pairs from the candidate frequencies identified in process block 312 .

[0101] In processing block 316, the LIDAR data generator 274 may calculate a period beat frequency for a comparison check for each of the candidate frequency pairs. In some cases, the LIDAR data generator 274 also calculates candidate LIDAR data for each of the candidate frequency pairs. For example, the LIDAR data generator 274 may use Equation 2 and / or Equation 3 to calculate the candidate distance (R i’ ) and / or candidate radial velocity (υ i’ ) can be calculated. i’ and / or υ i’ ) is the candidate frequency pair P i’ The LIDAR data generator 274 calculates the frequency for each candidate frequency pair P i’ Regarding the candidate distance and / or candidate radial velocity (R i’ and / or υ i’ ) for each candidate frequency pair P i’ (cf chk,i’ ) can be calculated for comparison checks. i’ Regarding the candidate distance and / or candidate radial velocity (R i’ and / or υ i’ ) is not calculated, f can be calculated by substituting Equation 2 and Equation 3 into Equation 5.ub and f db directly from the value of each candidate frequency pair P i’ (cf chk,i’ ) can be calculated for comparison checks.

[0102] In processing block 318, the LIDAR data validator 276 identifies valid frequency pairs and / or valid LIDAR data for the sample region. For example, the LIDAR data validator 276 may check one or more check criteria against each candidate frequency pair P i’ to identify valid frequency pairs and / or valid LIDAR data. In one example, the LIDAR data validator 276 may apply o )) 2 and n values ​​from 1 to 2N o For all values ​​up to i’,n = |cf chk,i’ -f chk,n The LIDAR data validator 276 calculates the value of X i’,n Among the results of o Identify the matched values. N of i' for the identified matched index o The value is the valid candidate frequency pair P i’ (valid frequency pair). In some cases, the LIDAR data validator 276 identifies valid LIDAR data in processing block 318. For example, the candidate LIDAR data associated with the identified i' value is identified as valid LIDAR data for sample region m. For example, the sample region is determined based on the distance R i and / or radial velocity υ i Thus, if the LIDAR data generator 274 calculates candidate LIDAR data for each of the candidate frequency pairs P in processing block 316, the candidate LIDAR data associated with the identified i' value can serve as valid LIDAR data for the sample area. For example, if the LIDAR data generator 274 calculates candidate LIDAR data for each of the candidate frequency pairs P in processing block 316,i’ For each of the candidate distances and / or candidate radial velocities (R i’ and / or υ i’ ) is calculated, the candidate distance (R i’ ) and / or the candidate radial velocity (υ i’ ) values ​​are used to calculate the effective range (Ri') values ​​and / or effective radial velocity (υ) values ​​for one or more objects within the sample volume. i’ ) value. If the sample region contains multiple objects, the effective distances (R i’ ) and the effective radial velocity (υ i’ ) are for the same object. As a result, LIDAR data for each different object within the sample region can be identified. Because valid LIDAR data is associated with the identified i' value, identifying valid LIDAR data also identifies valid frequency pairs by identifying which candidate LIDAR data results are calculated from candidate frequency pairs including first and second target frequencies associated with the same object.

[0103] If the LIDAR data generator 274 did not calculate candidate LIDAR data for each of the candidate frequency pairs in process block 316, the LIDAR data verifier 276 can calculate valid LIDAR data for the sample area using the identified i' values. For example, the LIDAR data verifier 276 can use Equation 2 and / or Equation 3 to calculate valid range and / or valid radial velocity (R i’ and / or υ i’ If the sample region contains multiple objects, the effective distance (R i’ ) and effective radial velocity (υ i’ ) values ​​correspond to the same object. As a result, it is possible to distinguish between LIDAR data for different objects within the sample region.

[0104] In processing block 320, the LIDAR data validator 276 can retain the valid LIDAR data for the sample area and / or make it available to an application for further processing. For example, the valid LIDAR data for the sample area can be saved to a storage device such as a memory and / or further processed. In some cases, the further processing includes error checking the valid LIDAR data. After further processing, the verified LIDAR data for the sample area can be saved to a storage device such as a memory and / or further processed. An application can access the valid LIDAR data and / or the verified LIDAR data for the sample area from the storage device or directly from the electronics 32. In processing block 322, the LIDAR data validator 276 can optionally discard and / or flag candidate frequency pairs and / or candidate LIDAR data for the sample area as invalid. As a result, the candidate frequency pair and / or the first portion of the candidate LIDAR data is classified as valid, while the candidate frequency pair and / or the second portion of the candidate LIDAR data is classified as invalid.

[0105] Although the LIDAR system is disclosed as having a system output signal with a frequency versus time pattern including two data periods of interest per sample region, the system output signal can also have a frequency versus time pattern including one data period of interest. For example, for a stationary field of view, the radial velocity of each sample region is zero. As a result, the range (R) is solved for one data period of interest. In these cases, candidate frequencies for the data period of interest can serve as candidate frequency pairs, f db or f ub can be set to zero depending on the frequency versus time pattern, and υ i’ The value of can be set to zero.

[0106] The LIDAR system is described as generating composite signals having multiple different beating frequencies when multiple objects are present within the sample volume and / or illuminated by the system output signal. However, composite signals having multiple different beating frequencies may also be generated from different surfaces of the same physical entity. As a result, multiple objects present within the sample volume and / or illuminated by the system output signal may also include multiple surfaces of the same physical entity.

[0107] Suitable electronics 32 include, but are not limited to, a controller including or consisting of analog electrical circuitry, digital electrical circuitry, a processor, a microprocessor, a digital signal processor (DSP), a field programmable gate array (FPGA), a computer, a microcomputer, or any combination suitable for performing the above-described operational, monitoring, and control functions. In some cases, the controller accesses a memory containing instructions executed by the controller in performing the above-described operational, control, and monitoring functions. In some cases, the functions of the LIDAR data generator and peak detector can be performed by a field programmable gate array (FPGA), a digital signal processor (DSP), an application-specific integrated circuit, firmware, software, hardware, and combinations thereof. While the electronics are illustrated as a single component in a single location, they can also include multiple distinct components located independently and / or in different locations. Also, as noted above, all or a portion of the disclosed electronics can be included on a chip, including integrated electronics on the chip.

[0108] Suitable platforms for LIDAR chips include, but are not limited to, silica, indium phosphide, and silicon-on-insulator wafers. Figure 7 shows a cross-sectional view of a portion of a chip constructed from a silicon-on-insulator wafer. A silicon-on-insulator (SOI) 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.

[0109] The portion of the chip illustrated in Figure 7 includes a waveguide structure suitable for use in a LIDAR chip constructed from a silicon-on-insulator wafer. A ridge 416 of an 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 the ridge 416 and a buried oxide layer 410.

[0110] The dimensions of the ridge waveguide are labeled in FIG. 7. For example, the width of the ridge is labeled w, and its height is labeled h. The thickness of the slab region is labeled T. These dimensions may be more critical for LIDAR applications than for other applications because they require the use of higher levels of optical power. The ridge width (labeled w) is greater than 1 μm and less than 4 μm, the ridge height (labeled 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. Thus, 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 slab thickness of 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 the slab region, with a thickness of at least 0.0 μm but less than 0.5 μm. While the above dimensions generally result in a single-mode structure in the straight or substantially straight portions of the waveguide, they can also result in multimode tapered and / or curved portions. Coupling between multimode and single-mode shapes can be achieved using tapers 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 propagating through a waveguide portion with multimode dimensions. The waveguide structure disclosed in connection with FIG. 7 is suitable for all or a portion of the waveguides on LIDAR chips constructed according to FIGS. 1A-1C.

[0111] The optical sensor that interfaces with the waveguide on the LIDAR chip can be attached to 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) manufactured by Hamamatsu Corporation, 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 attached to the edge of the chip on the facet to receive 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.

[0112] 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 interfaced 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 first auxiliary optical sensor 218, second auxiliary optical sensor 220, first optical sensor 223, and second optical sensor 224.

[0113] The light source 4 interfaced with the utility waveguide 12 can be a laser chip separate from the LIDAR chip and 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 functions as a reflector for an external cavity laser. In these cases, the light source 4 can be separate from the LIDAR chip and include a gain element 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, both of which are incorporated herein in their entireties. 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 level of current applied through the gain element or laser cavity.

[0114] The LIDAR system described above includes 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. The passive optical components can be solid-state components without active components. Suitable passive optical components include, but are not limited to, lenses, mirrors, optical gratings, reflective surfaces, splitters, demultiplexers, multiplexers, polarizers, polarization splitters, and polarization rotators. In some cases, the LIDAR system includes, 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, and tunable multiplexers.

[0115] Other embodiments, combinations, and modifications of the present invention will occur to those skilled in the art in view 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, different portions of the system output signal being transmitted during different data periods; combining light returning to the LIDAR system from the system output signal with light from a reference signal to generate pulsatile signals, each associated with one of the different data periods; generating a plurality of candidate frequencies for each data period, each candidate frequency for a data period representing a potential beat frequency for a beat signal associated with the data period; and Using the candidate frequencies for the check data period, identifying which of the candidate frequencies for the target data period are at the pulsatile frequency for the pulsatile signal associated with the target data period. A method comprising:

2. 10. The method of claim 1, further comprising calculating LIDAR data for objects within the sample volume from target frequencies of identified subjects, the LIDAR data indicating radial velocity and / or distance between the LIDAR system and the objects.

3. The method of claim 2 , wherein the LIDAR data for the object is not a function of any of the candidate frequencies during data periods of a subject that is not identified as being at a pulsatile frequency for the pulsatile signal.

4. 10. The method of claim 1, further comprising identifying a plurality of candidate frequency pairs, each candidate frequency pair including one candidate frequency from a target data period and a second candidate frequency from a second target data period; and Here, using the candidate frequencies from the check data period to identify which of the candidate frequencies associated with the target data period are at a beat frequency for a beat signal associated with the target data period includes identifying which of the candidate frequency pairs include a beat frequency for a beat signal associated with the target data period that is paired with a beat frequency for a beat signal associated with a second target data period.

5. 5. The method of claim 4, further comprising calculating a comparison beat frequency for each of the candidate frequency pairs, wherein the comparison beat frequency for each candidate frequency pair is calculated from a candidate frequency from a data period of a subject in the candidate frequency pair and from a candidate frequency from a data period of a second subject in the candidate frequency pair; A method in which the comparison beat frequency for each of the candidate frequency pairs represents a value that the beat frequency associated with the check data period may have if the beat frequency associated with the target data period is equal to the candidate frequency from the target data period in the candidate frequency pair and if the beat frequency associated with a second target data period is equal to the candidate frequency from the second target data period in the candidate frequency pair.

6. The method of claim 5, wherein identifying which of the candidate frequency pairs includes a beat frequency for a beat signal associated with a data period of the subject paired with a beat frequency for a beat signal associated with a data period of the second subject includes comparing the candidate frequency for the check data period with a comparison beat frequency for each of the candidate frequency pairs.

7. the target portion of the system output signal is transmitted during the target data period and the check portion of the system output signal is transmitted during the check data period; the frequency of the system output signal varies at different rates during the target data period and the check data period; wherein combining light returning to the LIDAR system from the system output signal with light from a reference signal comprises: combining light returning to the LIDAR system from a target portion of the system output signal with light from a target reference signal to generate a target pulsation signal beating at a target pulsation frequency; and combining light returning to the LIDAR system from a check portion of the system output signal with light from a check reference signal to generate a check pulsation signal pulsating at a check pulsation frequency; Including; generating candidate frequencies for each of the data periods; generating a target frequency at the target pulse frequency and a target image frequency at the additive inverse of the target pulse frequency; and generating a check candidate frequency at the check pulse frequency and a check image frequency at the additive inverse of the check pulse frequency. and The method of claim 1 , wherein using the candidate frequencies includes using the check candidate frequencies to identify which of the candidate frequencies of interest is a target frequency of interest.

8. The method of claim 1 , wherein each of the candidate frequencies is a frequency peak in a spectrum output from a real Fast Fourier Transform (FFT).

9. 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; calculating a plurality of different candidate LIDAR data results for the sample area, each of the different candidate LIDAR data results being a candidate for radial velocity and / or distance between the LIDAR system and an object within the sample area; and identifying which of the candidate LIDAR data results represent valid LIDAR data for the sample area; A method comprising:

10. 10. The method of claim 9, wherein a first target portion of the system output signal is transmitted during a first target data period, a second target portion of the system output signal is transmitted during a second target data period, and a check portion of the system output signal is transmitted during a check data period; the frequency of the system output signal varies at different rates during the first data period and the second data period; and The method comprises: combining light returning to the LIDAR system from the first subject portion of the system output signal with light from the first subject portion of a reference signal to generate a pulsation signal of the first subject beating at the pulsation frequency of the first subject; combining light returning to the LIDAR system from the second subject portion of the system output signal with light from the second subject portion of the reference signal to generate a pulsation signal of a second subject beating at a pulsation frequency of the second subject; combining light returning to the LIDAR system from a check portion of the system output signal with light from a check reference signal to generate a check pulsation signal pulsating at a check pulsation frequency; identifying a plurality of candidate frequencies of the first subject, the first candidate frequencies including a first target frequency at the beat frequency of the first subject and a first image frequency at the additive inverse of the beat frequency of the first subject; identifying a plurality of second candidate frequencies, the second candidate frequencies including a second target frequency at the second subject's beat frequency and a second image frequency at the additive inverse of the second subject's beat frequency; identifying a plurality of candidate check frequencies, the candidate check frequencies including a target check frequency at the check beat frequency and an image check frequency at the additive inverse of the check beat frequency; identifying a plurality of candidate frequency pairs, each candidate frequency pair including one of the first candidate frequencies and one of the second candidate frequencies; further comprising wherein calculating a plurality of different candidate LIDAR data results for the sample region includes calculating the candidate LIDAR data results from each of the candidate frequency pairs; and wherein identifying which of the candidate LIDAR data results represent valid LIDAR data for the sample area includes identifying which of the candidate LIDAR data results are calculated from the first target frequency and the second target frequency. method.

11. 11. The method of claim 10, wherein the candidate frequency pairs are identified such that there is one candidate frequency pair for each possible combination of one of the first candidate frequencies and one of the second candidate frequencies.

12. The method of claim 10 , wherein the LIDAR data results for each of the candidate frequency pairs are candidates for radial velocity and distance between the LIDAR system and an object within the sample region.

13. 11. The method of claim 10, further comprising calculating a comparative beat frequency for each of the candidate frequency pairs, wherein the comparative beat frequency for each candidate frequency pair is calculated from a first candidate frequency and a second candidate frequency in the candidate frequency pair; The method, wherein the comparison beat frequency for each of the candidate frequency pairs is an approximation of a value that a third target frequency would have if the first target frequency were equal to the first candidate frequency in the candidate frequency pair and the second target frequency were equal to the second candidate frequency in the candidate frequency pair.

14. 14. The method of claim 13, wherein identifying which of the candidate LIDAR data results are calculated from a candidate frequency pair including the first target frequency and the second target frequency includes comparing the third target frequency to the comparison beat frequency for each of the candidate frequency pairs.

15. 15. The method of claim 14, further comprising calculating coincidence indices, each of which is an absolute value of a difference between one of the comparison beat frequencies and one of the third target frequencies, one of the coincidence indices is calculated for each possible combination of one of the comparison beat frequencies and one of the third target frequencies; The method wherein the candidate LIDAR data result calculated from the candidate frequency pair associated with the lowest match index is identified as the candidate LIDAR data result calculated from the first target frequency and the second target frequency.

16. a LIDAR system configured to transmit a system output signal from the LIDAR system such that a sample area is illuminated by the system output signal, different portions of the system output signal being transmitted during different data periods; an optical signal combiner configured to combine light returning from the system output signal to the LIDAR system with light from a reference signal to generate pulsatile signals, each associated with a different data period; and and electronic equipment configured to generate a plurality of candidate frequencies for each of said data periods. A system comprising: Each of the candidate frequencies for a data period represents a potential beat frequency for the beat signal associated with that data period, and The system, wherein the electronics uses the candidate frequencies for the check data period to identify which of the candidate frequencies for the target data period are at the beat frequency for the beat signal associated with the target data period.

17. the electronics calculate LIDAR data for objects within the sample volume from the identified target frequencies of interest, the LIDAR data indicating a radial velocity and / or a distance between the LIDAR system and the objects; and 17. The system of claim 16, wherein the LIDAR data for the object is not a function of any of the candidate frequencies during data periods of a subject that is not identified as being at a pulsatile frequency for the pulsatile signal.

18. 17. The system of claim 16, the target portion of the system output signal is transmitted during the target data period and the check portion of the system output signal is transmitted during the check data period; the frequency of the system output signal varies at different rates during the target data period and the check data period; The optical signal combiner is configured to combine light returning from the system output signal to the LIDAR system with light from a reference signal, thereby: light returning to the LIDAR system from the target portion of the system output signal is combined with light from the target portion of the reference signal to generate a pulsation signal of a subject beating at a pulsation frequency of the subject; and light returning to the LIDAR system from the check portion of the system output signal is combined with light from the check portion of the reference signal to generate a check beat signal pulsating at a check beat frequency; the candidate frequencies include a target candidate frequency and a check candidate frequency; the candidate frequencies of interest include a target frequency of interest at the pulse frequency of the interest and an image frequency of interest at the additive inverse of the pulse frequency of the interest; and the candidate check frequencies include a check target frequency at a check beat frequency and a check image frequency at an additive inverse of the check beat frequency; and The system includes an electronic device using the candidate frequencies that uses the check candidate frequencies to identify which of the candidate frequencies of interest is a target frequency of interest.

19. a LIDAR system configured to transmit a system output signal such that a sample area is illuminated by the system output signal; and an electronic device for computing a plurality of different candidate LIDAR data results for the sample region; A system comprising: each of the different candidate LIDAR data results being a candidate for a radial velocity and / or a distance between the LIDAR system and an object within the sample volume; The electronics identify which of the candidate LIDAR data results represent valid LIDAR data for the sample area.

20. 20. The system of claim 19, a target portion of the system output signal is transmitted during a first target data period, a second target portion of the system output signal is transmitted during a second target data period, and a check portion of the system output signal is transmitted during a check data period; the frequency of the system output signal varies at different rates during the first data period and the second data period; and the system further comprises an optical signal combiner that combines light returning to the LIDAR system from a first subject portion of the system output signal with light from a first subject portion of a reference signal to generate a first subject pulsation signal pulsating at a first subject pulsation frequency; the optical signal combiner combines light returning to the LIDAR system from a second subject portion of the system output signal with light from a second subject portion of the reference signal to generate a pulsation signal of a second subject beating at a pulsation frequency of the second subject; the optical signal combiner combines light returning to the LIDAR system from the check portion of the system output signal with light from the check portion of the reference signal to generate a check beat signal pulsating at a check beat frequency; identifying which of the candidate LIDAR data results represent valid LIDAR data for the sample region includes identifying a plurality of first candidate frequencies, a plurality of second candidate frequencies, and a plurality of check candidate frequencies; the first candidate frequencies include a first target frequency at a beat frequency of a first object and a first image frequency at an additive inverse of the beat frequency of the first object; The second candidate frequencies include a second target frequency at a second beat frequency and a second image frequency at an additive inverse of the second beat frequency; and the third candidate frequency includes a third target frequency at a third beat frequency and a third image frequency at an additive inverse of the third beat frequency; Identifying which of the candidate LIDAR data results represent valid LIDAR data for the sample area includes identifying a plurality of candidate frequency pairs; each candidate frequency pair includes one of the first candidate frequencies and one of the second candidate frequencies; Computing a plurality of different candidate LIDAR data results for the sample area includes computing candidate LIDAR data results from each of the candidate frequency pairs; and The system, wherein identifying which of the candidate LIDAR data results represent valid LIDAR data for the sample area includes identifying which of the candidate LIDAR data results were calculated from the first target frequency and the second target frequency.

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