Measurement device, measurement method and program

Abstract

To provide a measurement device, a measurement method and a program capable of preventing measurement of a distance, using horizontal and vertical polarization, from deteriorating in precision.SOLUTION: A measurement device comprises: a transmission part which transmits a horizontal polarized light beam and a vertical polarized light beam toward an object of measurement; a reception part which receives horizontal reflected light of the horizontal polarized light beam reflected by the object of measurement and vertical reflected light of the vertical polarized light beam reflected by the object of measurement; a first measurement part which measures a first distance to the object of measurement according to reception timing of the horizontal reflected light; a second measurement part which measures a second distance to the object of measurement according to reception timing of the vertical reflected light; and a removal part which removes a vertical polarized component of the vertical reflected light in measuring the first distance and a horizontal polarized component of the horizontal reflected light in measuring the second distance.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a measurement device, a measurement method, and a program. [Background technology]

[0002] In recent years, LiDAR (Light Detection and Ranging) has been used to measure structures or monitor specific areas. LiDAR scans 3D (3-dimensional) by scanning with a laser beam. Therefore, the farther the object to be measured or monitored is, the wider the interval between the ranging points becomes, and the lower the point density of the point cloud data becomes.

[0003] Patent Document 1 discloses the configuration of a detection device that uses horizontally and vertically polarized light to increase the point density of point cloud data. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2023-509070 Summary of the Invention [Problem to be solved by the invention]

[0005] The detection device disclosed in Patent Document 1 emits horizontally and vertically polarized light and then receives the reflected light. Here, it is expected that crosstalk will occur, in which reflected light of either the horizontal or vertical polarized light is mixed with reflected light of the other polarized light. As a result of the crosstalk, there is a problem that the accuracy of distance measurements using the detection device disclosed in Patent Document 1 will deteriorate.

[0006] An object of the present disclosure is to provide a measurement device, a measurement method, and a program that can prevent deterioration in the accuracy of distance measurements using horizontally and vertically polarized light. [Means for solving the problem]

[0007] The measurement device according to the present disclosure includes a transmitting unit that transmits a horizontally polarized beam and a vertically polarized beam toward a measurement object, a receiving unit that receives horizontally reflected light of the horizontally polarized beam reflected at the measurement object and vertically reflected light of the vertically polarized beam reflected at the measurement object, a first measuring unit that measures a first distance to the measurement object in accordance with the timing of receiving the horizontally reflected light, a second measuring unit that measures a second distance to the measurement object in accordance with the timing of receiving the vertically reflected light, and a removing unit that removes the vertically polarized component of the vertically reflected light when measuring the first distance and the horizontally polarized component of the horizontally reflected light when measuring the second distance.

[0008] The measurement method according to the present disclosure transmits a horizontally polarized beam and a vertically polarized beam toward a measurement object, receives horizontally reflected light of the horizontally polarized beam reflected at the measurement object and vertically reflected light of the vertically polarized beam reflected at the measurement object, removes the vertically polarized component of the vertically reflected light when measuring a first distance to the measurement object using the horizontally polarized beam, removes the horizontally polarized component of the horizontally reflected light when measuring a second distance to the measurement object using the vertically polarized beam, measures the first distance to the measurement object according to the timing of receiving the horizontally reflected light, and measures the second distance to the measurement object according to the timing of receiving the vertically reflected light.

[0009] The program according to the present disclosure causes a computer to transmit a horizontally polarized beam and a vertically polarized beam toward a measurement target, receive horizontally reflected light of the horizontally polarized beam reflected at the measurement target and vertically reflected light of the vertically polarized beam reflected at the measurement target, remove the vertically polarized component of the vertically reflected light when measuring a first distance to the measurement target using the horizontally polarized beam, remove the horizontally polarized component of the horizontally reflected light when measuring a second distance to the measurement target using the vertically polarized beam, measure the first distance to the measurement target in accordance with the timing of receiving the horizontally reflected light, and measure the second distance to the measurement target in accordance with the timing of receiving the vertically reflected light. [Effects of the Invention]

[0010] The present disclosure can provide a measurement device, a measurement method, and a program that can prevent deterioration in the accuracy of distance measurements using horizontally and vertically polarized light. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 shows an example of the configuration of a measurement device according to the present disclosure. [Figure 2] FIG. 2 shows the flow of the measurement process executed in the measurement device according to the present disclosure. [Figure 3] FIG. 3 shows an example of the configuration of a measurement device according to the present disclosure. [Figure 4] FIG. 4 shows the optical and electrical signals used in the measurement device. [Figure 5] FIG. 5 shows a state in which the light emitted from the light beam scanning unit is scanning the surface of the measurement object. [Figure 6] FIG. 6 shows an example of the configuration of a coherent receiver. [Figure 7] FIG. 7 shows the timing of signals output by the components that make up the measuring device. [Figure 8] FIG. 8 shows a set of points on the surface of the object to be measured. [Figure 9]FIG. 9 shows the flow of the polarized beam transmission process executed in the measurement device. [Figure 10] FIG. 10 shows the flow of the polarized beam reception process executed in the measurement device. [Figure 11] FIG. 11 shows the flow of the point cloud data generation process executed in the measuring device. [Figure 12] FIG. 12 shows an example of the configuration of the compensation unit. [Figure 13] FIG. 13 is a block diagram showing an example of the configuration of the measurement device 10 and the measurement device 20. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Embodiment 1) 1 shows an example configuration of a measurement device 10 according to the present disclosure. The measurement device 10 may be a computer device operated by a processor executing a program stored in a memory. The measurement device may be a distance measuring device that measures the distance between the measurement device and an object. The distance measuring device may be, for example, a LiDAR device or a 3D scanner.

[0013] The measurement device 10 has a transmitter 11, a receiver 12, a measurement unit 13, a measurement unit 14, and a removal unit 15. The transmitter 11, receiver 12, measurement unit 13, measurement unit 14, and removal unit 15 may be software or modules whose processing is performed by a processor executing a program stored in a memory. Alternatively, the transmitter 11, receiver 12, measurement unit 13, measurement unit 14, and removal unit 15 may be hardware such as a circuit or a chip.

[0014] The transmitting unit 11 may be used as a means for transmitting a signal, light, laser, beam, etc. The receiving unit 12 may be used as a means for receiving a signal, light, laser, beam, etc. The measuring units 13 and 14 may be used as a means for measuring distance, time, etc. The removing unit 15 may be used as a means for removing information or data.

[0015] The transmitter 11 transmits a horizontally polarized beam and a vertically polarized beam toward the object to be measured. The horizontally polarized beam and the vertically polarized beam may be modulated laser light. The polarization plane of the horizontally polarized beam is substantially orthogonal to the polarization plane of the vertically polarized beam. "Substantially orthogonal" includes not only a state in which the polarization planes are completely orthogonal to each other, but also a state in which the polarization planes are tilted by a predetermined angle from the orthogonal state. The modulated laser light may be, for example, an optical signal containing pulse information. "Transmitting a beam" may be another way of saying "emitting a beam." The object to be measured may be a stationary object such as a building or plant, or a moving object such as a vehicle or person.

[0016] Transmitter 11 may transmit the horizontally polarized beam and the vertically polarized beam at substantially the same timing, or may transmit them at different timings.

[0017] Receiving unit 12 receives horizontally reflected light of the horizontally polarized beam reflected by the object to be measured and vertically reflected light of the vertically polarized beam reflected by the object to be measured. Receiving reflected light may be rephrased as receiving reflected light.

[0018] Measurement unit 13 measures a first distance to the measurement target in response to the timing of receiving the horizontally reflected light. The first distance to the measurement target may be the distance from measurement device 10 to a point on the measurement target where the horizontally polarized beam is reflected. The point of reflection may be referred to as a reflection point.

[0019] Measurement unit 14 measures a second distance to the measurement target in response to the timing of receiving the vertically reflected light. The second distance to the measurement target may be the distance from measurement device 10 to the point on the measurement target where the vertically polarized beam is reflected.

[0020] Measuring the distance according to the timing of receiving the reflected light may be, for example, measuring the distance using a ToF (Time of Flight) method.

[0021] Although the measurement unit 13 and the measurement unit 14 are shown as different functional blocks in FIG. 1, they may be one functional block.

[0022] The removal unit 15 removes the vertically polarized component of the vertically reflected light when measuring the first distance, and further removes the horizontally polarized component of the horizontally reflected light when measuring the second distance.

[0023] The first distance is measured using the horizontally polarized component. Therefore, the vertically polarized component when measuring the first distance is estimated to be the effect of crosstalk caused by vertically reflected light. The second distance is measured using the vertically polarized component. Therefore, the horizontally polarized component when measuring the second distance is estimated to be the effect of crosstalk caused by horizontally reflected light. Therefore, the removal unit 15 removes the effect of crosstalk, or in other words, removes crosstalk.

[0024] 2 shows the flow of measurement processing executed by measurement device 10 according to the present disclosure. First, transmitter 11 transmits a horizontally polarized beam and a vertically polarized beam toward the measurement target (S11). Next, receiver 12 receives horizontally reflected light of the horizontally polarized beam and vertically reflected light of the vertically polarized beam (S12).

[0025] Next, removal unit 15 removes the vertically polarized component of the vertically reflected light when measuring a first distance to the measurement target using the horizontally polarized beam (S13). Next, removal unit 15 removes the horizontally polarized component of the horizontally reflected light when measuring a second distance to the measurement target using the vertically polarized beam (S14). Step S13 may be performed after step S14, or steps S13 and S14 may be performed at substantially the same timing.

[0026] Next, the measurement unit 13 measures a first distance to the measurement object in response to the timing of receiving the horizontally reflected light (S15). Next, the measurement unit 14 measures a second distance to the measurement object in response to the timing of receiving the vertically reflected light (S16). Step S15 may be performed after step S16, or steps S15 and S16 may be performed at substantially the same timing.

[0027] As described above, measurement device 10 removes the vertically polarized component in measurements using a horizontally polarized beam, and removes the horizontally polarized component in measurements using a vertically polarized beam. This allows measurement device 10 to improve the accuracy of distance measurements when using a horizontally polarized beam and when using a vertically polarized beam.

[0028] (Embodiment 2) Fig. 3 shows an example configuration of a measurement device 20 according to the present disclosure. The measurement device 20 corresponds to the measurement device 10 in Fig. 1. The measurement device 20 may be a computer device that operates by a processor executing a program stored in a memory.

[0029] The measuring device 20 has a light source 21, an optical modulator 22, a modulated signal generator 23, a circulator 24, an optical transmitter / receiver 25, a polarized beam splitter 26, and an optical beam scanner 27. The light source 21, the optical modulator 22, the modulated signal generator 23, the circulator 24, the optical transmitter / receiver 25, the polarized beam splitter 26, and the optical beam scanner 27 correspond to the transmitter 11 in the measuring device 10 of FIG. 1. The optical modulator 22 may be used as a means for modulating an optical signal. The modulated signal generator 23 may be used as a means for generating a modulated signal. The optical transmitter / receiver 25 may be used as a means for transmitting or receiving an optical signal. The optical beam scanner 27 may be used as a means for scanning an optical beam.

[0030] 1. Furthermore, the measurement device 20 has a coherent receiver 28. The coherent receiver 28 corresponds to the receiving unit 12 in the measurement device 10 of FIG. 1. The circulator 24 and the optical transceiver 25 also correspond to the receiving unit 12 in the measurement device 10 of FIG. 1. Furthermore, the measurement device 20 has a compensation unit 29. The compensation unit 29 corresponds to the removal unit 15 in the measurement device 10 of FIG. 1. Furthermore, the measurement device 20 has a timing extraction unit 30, a timing extraction unit 31, a distance measurement unit 32, a distance measurement unit 33, and a point cloud synthesis unit 34. The timing extraction unit 30, the timing extraction unit 31, the distance measurement unit 32, the distance measurement unit 33, and the point cloud synthesis unit 34 correspond to the measurement unit 14 in the measurement device 10 of FIG. 1.

[0031] The light source 21 generates light. For example, the light source 21 generates continuous wave (CW) light. FIG. 4 shows the light and electrical signals used in the measurement device 20. FIG. 4 shows an image of the continuous light. f0 indicates the frequency of the continuous light. The frequency of the continuous light is constant at f0, and the amplitude of the continuous light is also constant as shown in FIG. 4. The horizontal axis of FIG. 4 indicates time, and the vertical axis indicates signal intensity.

[0032] Returning to Fig. 3, the modulation signal generation unit 23 generates a modulation signal. The modulation signal may be referred to as a drive signal, for example. The drive signal is an electrical signal. As shown in Fig. 4, the drive signal is an electrical signal with a frequency f1. The drive signal may be a pulse signal that appears at a predetermined timing.

[0033] Returning to FIG. 3, the optical modulation unit 22 modulates the continuous light using a modulation signal. For example, as shown in FIG. 4, the optical modulation unit 22 may add a modulation signal having a frequency of f1 to continuous light having a frequency of f0, thereby changing the frequency of the continuous light at the point where the modulation signal is added to f0+f1. Adding a modulation signal having a frequency of f1 to continuous light having a frequency of f0 may be referred to as frequency modulation. Adding a modulation signal having a frequency of f1 may also be referred to as adding a frequency offset of f1. Furthermore, FIG. 4 shows changing the intensity at the point where the modulation signal is added. Changing the intensity may be referred to as intensity modulation or pulsing. Alternatively, the optical modulation unit 22 may add a modulation signal having a frequency of f2 to continuous light having a frequency of f0, thereby changing the frequency of the continuous light at the point where the modulation signal is added to f0+f2. Light having a modulation signal having a frequency of f0+f1 may be a vertically polarized beam, and light having a modulation signal having a frequency of f0+f2 may be a horizontally polarized beam.

[0034] As shown in Figure 4, the frequency-modulated and intensity-modulated continuous light is referred to as transmitted light. The transmitted light having a frequency of f0+f1 may be light whose spectrum is confirmed at the frequency positions of f0 and f1 at the timing when the modulated signal is added, for example, when spectrum analysis is performed. In Figure 4, the magnitude of the signal intensity of the continuous light is not shown in order to clearly show the points in the transmitted light where the modulated signal is added. The transmitted light in Figure 4 represents an optical pulse signal.

[0035] 3, the circulator 24 outputs the transmitted light to the optical transmitter / receiver 25. The circulator 24 also outputs the received light to a coherent receiver 28, which will be described later.

[0036] Optical transceiver 25 outputs the transmitted light to polarizing beam splitter 26. Polarizing beam splitter 26 splits the transmitted light into a horizontally polarized beam and a vertically polarized beam. The horizontal polarization plane of the horizontally polarized beam is substantially orthogonal to the vertical polarization plane of the vertically polarized beam. Furthermore, polarizing beam splitter 26 sets the polarization angle between the horizontally polarized beam and the vertically polarized beam to a predetermined angle. By setting the polarization angle between the horizontally polarized beam and the vertically polarized beam, the horizontally polarized beam is emitted at a different angle from the vertically polarized beam.

[0037] The light beam scanning unit 27 scans with the horizontally polarized beam and the vertically polarized beam. In other words, the light beam scanning unit 27 outputs or emits the horizontally polarized beam and the vertically polarized beam so as to scan the surface of the measurement object. Figure 5 shows a state in which the light emitted from the light beam scanning unit 27 is scanning the surface of the measurement object.

[0038] Of the emitted light in Figure 5, the emitted light shown by the solid line is a horizontally polarized beam, and the emitted light shown by the dashed line is a vertically polarized beam. The horizontally polarized beam and the vertically polarized beam scan the area shown as the measurement target. The horizontally polarized beam and the vertically polarized beam scan different parts of the area shown as the measurement target because the deflection angles are set in the polarizing beam splitter 26. The reflected light shown by the solid line is a horizontally polarized beam, and the reflected light shown by the dashed line is a vertically polarized beam.

[0039] 3, the optical transmitter / receiver 25 receives the light reflected by the object to be measured as the received light. The circulator 24 outputs the received light to the coherent receiver .

[0040] The coherent receiver 28 receives the received light from the optical transmitter / receiver 25 via the circulator 24. Furthermore, the coherent receiver 28 receives the continuous light from the light source 21 as reference light. The coherent receiver 28 identifies the horizontally polarized component and the vertically polarized component from the received light using a coherent detection method.

[0041] Here, an overview of the coherent detection method will be described using FIG. 6. FIG. 6 shows an example of the configuration of the coherent receiver 28. The coherent receiver 28 has a separator 41 and an identifier 42. The separator 41 and the identifier 42 may be software or modules whose processes are executed by a processor executing a program stored in a memory. Alternatively, the separator 41 and the identifier 42 may be hardware such as a circuit or a chip. The separator may be used as a means for separating polarization-multiplexed light. The identifier may be used as a means for identifying information or data.

[0042] The separator 41 performs polarization separation on the polarization-multiplexed received light. The coherent receiver 28 may perform polarization separation on the received light using, for example, a separation filter as the separator 41. The polarization separation process may be performed by digital signal processing in a processor. After performing polarization separation, the separator 41 outputs the horizontally polarized beam and the vertically polarized beam to the identification unit 42.

[0043] The determination unit 42 determines or extracts the horizontally polarized component and the vertically polarized component by causing interference between the horizontally polarized beam, the vertically polarized beam, and the reference light. The determination unit 42 outputs the vertically polarized component, which is an electrical signal, to the timing extraction unit 30, and outputs the horizontally polarized component, which is an electrical signal, to the timing extraction unit 31.

[0044] Here, the optical or electrical signals output by each component of the measurement device 20 will be described. Fig. 7 shows the timing of the signals output by each component. The horizontal axis in Fig. 7 represents time. Moving to the right on the horizontal axis indicates that more time has passed. t1 to t8 each represent a time or timing.

[0045] The optical transceiver 25 outputs polarization-multiplexed transmission light at t1. The transmission light includes a horizontally polarized beam having a frequency of f0+f1 and a vertically polarized beam having a frequency of f0+f2. The polarizing beam splitter 26 outputs the vertically polarized beam and the horizontally polarized beam after polarization separation. The timing at which the optical transceiver 25 outputs the transmission light and the timing at which the polarizing beam splitter 26 outputs the vertically polarized beam and the horizontally polarized beam are actually different. However, the difference between the timing at which the optical transceiver 25 outputs the transmission light and the timing at which the polarizing beam splitter 26 outputs the vertically polarized beam and the horizontally polarized beam are sufficiently small. Therefore, for ease of explanation, the timing at which the polarizing beam splitter 26 outputs the vertically polarized beam and the horizontally polarized beam will be described as t1.

[0046] Optical transceiver 25 receives the reflected light of the vertically polarized beam at t2 and receives the reflected light of the horizontally polarized beam at t3. The period during which the reflected light of the vertically polarized beam is received and the period during which the reflected light of the horizontally polarized beam is received overlap. The horizontally polarized beam and the vertically polarized beam output at substantially the same time at t1 are reflected at different locations on the surface of the object to be measured. Therefore, the time t2 at which optical transceiver 25 receives the reflected light of the vertically polarized beam differs from the time t3 at which the reflected light of the horizontally polarized beam is received.

[0047] Furthermore, the timing when the coherent receiver 28 outputs the vertically polarized component is set to t2, and the timing when the coherent receiver 28 outputs the horizontally polarized component is set to t3. Although the timing when the optical transceiver 25 receives the reflected light and the timing when the coherent receiver 28 outputs the vertically polarized component and the horizontally polarized component are actually different, for ease of explanation, they are described as being the same timing.

[0048] 7 shows that the vertically polarized component output by the coherent receiver 28 contains a horizontally polarized component. It also shows that the horizontally polarized component output by the coherent receiver 28 contains a vertically polarized component. In other words, the horizontally polarized component leaks into the vertically polarized component output by the coherent receiver 28, and the vertically polarized component leaks into the horizontally polarized component output by the coherent receiver 28. The horizontally polarized component included in the vertically polarized component and the vertically polarized component included in the horizontally polarized component may be referred to as crosstalk.

[0049] The time from t1 to t5 indicates the transmission pulse repetition period. In other words, t1 and t5 may be the timings at which the modulation signal generating unit 23 modulates the continuous light.

[0050] At t6, optical transceiver 25 receives the reflected light of the horizontally polarized beam, and coherent receiver 28 outputs the horizontally polarized component. Furthermore, at t7, optical transceiver 25 receives the reflected light of the vertically polarized beam, and coherent receiver 28 outputs the vertically polarized component. t6 and t8 indicate that the period for receiving the reflected light of the vertically polarized beam and the period for receiving the reflected light of the horizontally polarized beam do not overlap. Also, it is shown that the reflected light of the horizontally polarized beam received by optical transceiver 25 at t6 contains a vertically polarized component, and that the reflected light of the vertically polarized beam received by optical transceiver 25 at t7 contains a horizontally polarized component.

[0051] Returning to FIG. 3, compensation unit 29 removes crosstalk. Removing crosstalk can be said to reduce the effects of crosstalk. For example, a case will be described in which the period for receiving reflected light of a vertically polarized beam and the period for receiving reflected light of a horizontally polarized beam overlap, as in t2 and t3. In such a case, compensation unit 29 may operate, for example, as a bandpass filter that passes only signals in a specific frequency band.

[0052] For example, compensating unit 29 may pass only signals of frequency f1 for reflected vertically polarized beams. "Passing" may be synonymous with "transmitting." Furthermore, compensating unit 29 may pass only signals of frequency f2 for reflected horizontally polarized beams. As a result, compensating unit 29 removes the horizontally polarized component of frequency f2 contained in the reflected vertically polarized beams, and removes the vertically polarized component of frequency f1 contained in the reflected horizontally polarized beams.

[0053] In addition, compensation unit 29 may also operate as a bandpass filter that passes only signals in a specific frequency band, even when the reception period of the reflected light of the vertically polarized beam and the reception period of the reflected light of the horizontally polarized beam do not overlap, such as t6 and t7.

[0054] Alternatively, compensation unit 29 may remove signals with an intensity lower than a predetermined threshold when the reception period of the reflected light of the vertically polarized beam and the reception period of the reflected light of the horizontally polarized beam do not overlap, as in t6 and t7. At t6 in FIG. 7, the horizontally polarized component leaks into the vertically polarized component when the reflected light of the horizontally polarized beam is received. The horizontally polarized component leaking into the vertically polarized component has an intensity sufficiently lower than that of the horizontally polarized component output to timing extraction unit 31. Furthermore, the vertically polarized component leaking into the horizontally polarized component also has an intensity sufficiently lower than that of the vertically polarized component output to timing extraction unit 30. Therefore, compensation unit 29 can remove signals with an intensity lower than a predetermined threshold to eliminate crosstalk.

[0055] Returning to FIG. 3, timing extraction section 30 uses the vertically polarized component to identify the time from when optical transceiver 25 transmits the vertically polarized beam until when it receives the reflected light of the vertically polarized beam.

[0056] Timing extraction unit 31 uses the horizontally polarized component to identify the time from when optical transceiver 25 transmits the horizontally polarized beam until when it receives the reflected light of the horizontally polarized beam.

[0057] Distance measurement unit 32 determines the distance to the reflection point of the vertically polarized beam on the measurement target by executing the ToF method using the time determined by timing extraction unit 30. Furthermore, distance measurement unit 33 determines the distance to the reflection point of the horizontally polarized beam on the measurement target by executing the ToF method using the time determined by timing extraction unit 31. Distance D1 to the reflection point of the vertically polarized beam is calculated as D1 = speed of light × (t2 - t1) / 2, where " / " indicates division. "t2 - t1" indicates the time determined by timing extraction unit 30. Distance D2 to the reflection point of the horizontally polarized beam is calculated as D2 = speed of light × (t3 - t1) / 2, where "t3 - t1" indicates the time determined by timing extraction unit 31.

[0058] The point cloud synthesis unit 34 synthesizes the reflection points whose distances are determined by the distance measurement unit 33 to generate point cloud data. The point cloud data may be a collection of points, for example, as shown in FIG. 8. FIG. 8 shows a collection of points on the surface of the object to be measured. For example, the black circles may be reflection points of the vertically polarized beam, and the white circles may be reflection points of the horizontally polarized beam. FIG. 8 shows that the reflection points of the horizontally polarized beam are arranged horizontally between the reflection points of the vertically polarized beam and the reflection points of the vertically polarized beam that are arranged horizontally, but this is not limited to this. For example, the left half of the object may be scanned with a vertically polarized beam, and the right half of the object may be scanned with a vertically polarized beam. In this case, the point cloud representing the left half of the object represents the reflection points of the vertically polarized beam, and the point cloud representing the right half of the object represents the reflection points of the vertically polarized beam. Alternatively, the vertically polarized beam may scan the upper half of the object, and the vertically polarized beam may scan the lower half of the object. In this case, the point cloud representing the upper half of the object represents the reflection points of the vertically polarized beam, and the point cloud representing the lower half of the object represents the reflection points of the vertically polarized beam.

[0059] 9 shows the flow of the polarized beam transmission process executed in the measurement device 20.

[0060] First, optical modulator 22 modulates continuous light using a modulation signal (S21). Next, polarizing beam splitter 26 splits the transmitted light into a horizontally polarized beam and a vertically polarized beam (S22). Next, optical beam scanner 27 scans the horizontally polarized beam and the vertically polarized beam over the object to be measured (S23).

[0061] 10 shows the flow of the polarized beam reception process executed in the measurement device 20.

[0062] First, optical modulation unit 22 receives reflected light of the horizontally polarized beam and vertically polarized beam transmitted from optical beam scanning unit 27 (S31). Next, coherent receiver 28 depolarizes the polarization-multiplexed reflected light (S32).

[0063] Next, the coherent receiver 28 causes each of the polarization-separated reflected lights to interfere with the reference light (S33). Next, the compensation unit 29 removes crosstalk in the vertically polarized component and the horizontally polarized component (S34). The compensation unit 29 may pass light of a specific frequency and remove light other than the specific frequency. Alternatively, the compensation unit 29 may remove light with an intensity lower than a predetermined threshold.

[0064] Next, the process for generating point cloud data will be described. Fig. 11 shows the flow of the process for generating point cloud data executed in the measuring device 20.

[0065] First, timing extraction unit 30 determines the time from transmitting a vertically polarized beam to receiving reflected light of the vertically polarized beam (S41). Next, timing extraction unit 31 determines the time from transmitting a horizontally polarized beam to receiving reflected light of the horizontally polarized beam (S42). The order of steps S41 and S42 may be reversed. Alternatively, step S41 may be executed independently of step S42. Executing independently may mean executing them in parallel. Therefore, steps S41 and S42 may be executed at substantially the same timing, or the timing of the processing may overlap.

[0066] Next, distance measurement unit 32 determines the distance to the reflection point of the vertically polarized beam on the measurement target based on the time determined by timing extraction unit 30 (S43). Determining may be rephrased as measuring. Next, distance measurement unit 33 determines the distance to the reflection point of the horizontally polarized beam on the measurement target based on the time determined by timing extraction unit 31 (S44). The order of steps S43 and S44 may be reversed. Alternatively, step S43 may be performed independently of step S44.

[0067] Next, the point cloud synthesis unit 34 synthesizes the reflection points whose distances have been specified by the distance measurement unit 33 to generate point cloud data (S45).

[0068] As described above, measurement apparatus 20 removes crosstalk in compensation unit 29. If crosstalk is not removed, for example, timing extraction unit 31 will measure distance D2 to the reflection point of the horizontally polarized beam using t2, which is the timing at which the vertically polarized component leaking into the horizontally polarized component is received. Because a time error occurs between t3, which should be used, and t2, the measurement accuracy of distance D2 to the reflection point of the horizontally polarized beam will also deteriorate. On the other hand, by removing crosstalk using compensation unit 29, timing extraction unit 31 measures distance D2 to the reflection point of the horizontally polarized beam using t3. As a result, the measurement accuracy of distance D2 to the reflection point of the horizontally polarized beam improves.

[0069] (Embodiment 3) Next, a description will be given of a process for removing crosstalk performed by compensation unit 29 that is different from that in the second embodiment. Fig. 12 shows an example configuration of compensation unit 29. Coefficient assigning units 51 and 52 assign coefficients to the vertical polarization component. Assigning a coefficient may mean multiplying the vertical polarization component by the coefficient. Coefficient assigning units 53 and 54 assign coefficients to the vertical polarization component.

[0070] Adder 55 adds the vertical polarization component multiplied by the coefficient in coefficient assigner 51 and the horizontal polarization component multiplied by the coefficient in coefficient assigner 53. Adder 56 adds the vertical polarization component multiplied by the coefficient in coefficient assigner 52 and the horizontal polarization component multiplied by the coefficient in coefficient assigner 54.

[0071] Coefficient calculation unit 57 updates the coefficients in coefficient assignment units 51-54 so that only the vertical polarization component of frequency f1 is output from the signal output from adder 55 and only the horizontal polarization component of frequency f2 is output from the signal output from adder 56. The coefficients used in coefficient assignment units 51-54 may each have a different value. After updating the coefficients in coefficient assignment units 51-54, coefficient calculation unit 57 sets the updated coefficients in coefficient assignment units 51-54.

[0072] As described above, the coefficient calculation unit 57 analyzes the signals output from the addition unit 55 and the addition unit 56. The coefficient calculation unit 57 eliminates or minimizes the influence of crosstalk by feeding back the analysis result to the coefficient assignment units 51 to 54. As a result, the accuracy of the point cloud data generated in the point cloud synthesis unit 34 is improved.

[0073] FIG. 13 is a block diagram showing an example configuration of the measuring device 10 and the measuring device 20 (hereinafter referred to as the measuring device 10, etc.). Referring to FIG. 13, the measuring device 10, etc. includes a network interface 1201, a processor 1202, and a memory 1203. The network interface 1201 may be used to communicate with a network node. The network interface 1201 may include, for example, a network interface card (NIC) that complies with the IEEE 802.3 series. IEEE stands for Institute of Electrical and Electronics Engineers.

[0074] The processor 1202 reads and executes software (computer programs) from the memory 1203 to perform the processes of the measuring device 10 and the like described using the flowcharts. The processor 1202 may be, for example, a microprocessor, an MPU, or a CPU. The processor 1202 may include multiple processors.

[0075] The memory 1203 is configured by a combination of volatile memory and non-volatile memory. The memory 1203 may include storage located remotely from the processor 1202. In this case, the processor 1202 may access the memory 1203 via an I / O (Input / Output) interface (not shown).

[0076] 13, memory 1203 is used to store software modules. Processor 1202 can perform processing of measurement device 10, etc. by reading and executing these software modules from memory 1203.

[0077] As described with reference to FIG. 13, each of the processors included in the measurement device 10 etc. executes one or more programs including a group of instructions for causing a computer to perform the algorithm described with reference to the drawings.

[0078] In the above examples, the program includes instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The program may be stored on a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable medium or tangible storage medium includes random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disc (DVD), Blu-ray® disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device. The program may also be transmitted on a transitory computer-readable medium or communication medium. By way of example and not limitation, transitory computer-readable medium or communication medium includes electrical, optical, acoustic, or other forms of propagated signals.

[0079] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0080] Each drawing is merely an example for describing one or more embodiments. Each drawing may relate not only to one particular embodiment, but also to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0081] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes. (Appendix 1) a transmitter that transmits a horizontally polarized beam and a vertically polarized beam toward a measurement target; a receiving unit that receives horizontally reflected light of the horizontally polarized beam reflected by the object to be measured and vertically reflected light of the vertically polarized beam reflected by the object to be measured; a first measurement unit that measures a first distance to the measurement object in accordance with a timing of receiving the horizontally reflected light; a second measurement unit that measures a second distance to the measurement object in accordance with a timing at which the vertically reflected light is received; a removal unit that removes the vertical polarization component of the vertically reflected light when measuring the first distance and the horizontal polarization component of the horizontally reflected light when measuring the second distance. (Appendix 2) The removal unit 2. The measurement device of claim 1, wherein the vertically polarized component having an intensity less than a first threshold and the horizontally polarized component having an intensity less than a second threshold are removed. (Appendix 3) The transmission unit transmitting the horizontally polarized beam to which a first frequency offset has been added and the vertically polarized beam to which a second frequency offset has been added toward the measurement target; The removal unit 2. The measurement apparatus of claim 1, wherein, when measuring the first distance, the vertical polarization component having a frequency offset different from the first frequency offset is removed, and when measuring the second distance, the horizontal polarization component having a frequency offset different from the second frequency offset is removed. (Appendix 4) The removal unit 4. The measurement device of claim 3, further comprising a first filter that transmits a horizontally polarized component having the first frequency and a second filter that transmits a vertically polarized component having the second frequency. (Appendix 5) The removal unit when measuring the first distance, generating an updated horizontal polarization component by adding together the horizontal polarization component multiplied by a first coefficient and the vertical polarization component multiplied by a second coefficient, and when measuring the second distance, generating an updated vertical polarization component by adding together the horizontal polarization component multiplied by a third coefficient and the vertical polarization component multiplied by a fourth coefficient; The measurement device described in Appendix 1, further comprising a coefficient determination unit that determines the first to fourth coefficients so as to reduce the vertical polarization component included in the updated horizontal polarization component and reduce the horizontal polarization component included in the updated vertical polarization component. (Appendix 6) The receiving unit a separation unit that separates received light including a horizontally polarized component and a vertically polarized component into the horizontally reflected light having the horizontally polarized component and the vertically reflected light having the vertically polarized component; 6. The measurement device according to claim 1, further comprising: an identifying unit that removes light components from the horizontally reflected light and the vertically reflected light and identifies the horizontally polarized component and the vertically polarized component. (Appendix 7) The identification unit 7. The measurement device of claim 6, wherein the horizontally polarized component and the vertically polarized component are identified using a coherent detection method. (Appendix 8) 8. The measurement device according to claim 1, further comprising a generating unit that generates point cloud data by combining the first distance and the second distance. (Appendix 9) Transmitting a horizontally polarized beam and a vertically polarized beam toward a measurement target; receiving horizontally reflected light of the horizontally polarized beam reflected by the object to be measured and vertically reflected light of the vertically polarized beam reflected by the object to be measured; removing a vertically polarized component of the vertically reflected light when measuring a first distance to the measurement object using the horizontally polarized beam; removing a horizontally polarized component of the horizontally reflected light when measuring a second distance to the measurement object using the vertically polarized beam; measuring a first distance to the measurement target in accordance with a timing of receiving the horizontally reflected light; A measurement method in which a second distance to the measurement object is measured in accordance with the timing of receiving the vertically reflected light. (Appendix 10) Transmitting a horizontally polarized beam and a vertically polarized beam toward a measurement target; receiving horizontally reflected light of the horizontally polarized beam reflected by the object to be measured and vertically reflected light of the vertically polarized beam reflected by the object to be measured; removing a vertically polarized component of the vertically reflected light when measuring a first distance to the measurement object using the horizontally polarized beam; removing a horizontally polarized component of the horizontally reflected light when measuring a second distance to the measurement object using the vertically polarized beam; measuring a first distance to the measurement target in accordance with a timing of receiving the horizontally reflected light; A program that causes a computer to measure a second distance to the measurement object in accordance with the timing of receiving the vertically reflected light.

[0082] Some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 2 to 8 that are dependent on Supplementary Note 1 may also be dependent on Supplementary Notes 9 and 10 in the same dependency relationship as Supplementary Notes 2 to 8. Some or all of the elements described in any Supplementary Note may be applied to various hardware, software, recording means for recording software, systems, and methods. [Explanation of symbols]

[0083] 10. Measuring equipment 11 Transmitter 12 Receiving unit 13 Measuring part 14 Measuring part 15 Removal part 20 Measuring Equipment 21 Light source 22 Optical modulation section 23 Modulation signal generator 24 Circulator 25 Optical transmitter / receiver 26 Polarizing Beam Splitter 27 Light beam scanning unit 28 Coherent Receiver 29 Compensation Department 30 Timing extraction unit 31 Timing extraction unit 32 Distance measurement unit 33 Distance measurement unit 34 Point group synthesis section 41 Separation section 42 Specific part 51 Coefficient assignment section 52 Coefficient assignment section 53 Coefficient assignment section 54 Coefficient assignment section 55 Addition section 56 Addition section 57 Coefficient calculation section

Claims

1. a transmitter that transmits a horizontally polarized beam and a vertically polarized beam toward a measurement target; a receiving unit that receives horizontally reflected light of the horizontally polarized beam reflected by the object to be measured and vertically reflected light of the vertically polarized beam reflected by the object to be measured; a first measurement unit that measures a first distance to the measurement object in accordance with a timing at which the horizontally reflected light is received; a second measurement unit that measures a second distance to the measurement target in accordance with a timing at which the vertically reflected light is received; a removal unit that removes the vertical polarization component of the vertically reflected light when measuring the first distance and the horizontal polarization component of the horizontally reflected light when measuring the second distance.

2. The removal unit 2. The measurement device of claim 1, wherein the vertically polarized components having an intensity less than a first threshold and the horizontally polarized components having an intensity less than a second threshold are removed.

3. The transmission unit transmitting the horizontally polarized beam to which a first frequency offset has been added and the vertically polarized beam to which a second frequency offset has been added toward the measurement target; The removal unit 2. The measurement device of claim 1, wherein the vertical polarization component having a frequency offset different from the first frequency offset is removed when measuring the first distance, and the horizontal polarization component having a frequency offset different from the second frequency offset is removed when measuring the second distance.

4. The removal unit 4. The measurement apparatus of claim 3, further comprising a first filter that transmits the horizontally polarized component having the first frequency offset, and a second filter that transmits the vertically polarized component having the second frequency offset.

5. The removal unit when measuring the first distance, generating an updated horizontal polarization component by adding together the horizontal polarization component multiplied by a first coefficient and the vertical polarization component multiplied by a second coefficient, and when measuring the second distance, generating an updated vertical polarization component by adding together the horizontal polarization component multiplied by a third coefficient and the vertical polarization component multiplied by a fourth coefficient; 2. The measurement device according to claim 1, further comprising a coefficient determination unit that determines the first to fourth coefficients so as to reduce the vertical polarization component included in the updated horizontal polarization component and reduce the horizontal polarization component included in the updated vertical polarization component.

6. The receiving unit a separation unit that separates the horizontally reflected light having the horizontal polarization component and the vertically reflected light having the vertical polarization component from received light including the horizontal polarization component and the vertical polarization component; The measurement device according to claim 1 , further comprising: an identifying unit that removes light components from the horizontally reflected light and the vertically reflected light and identifies the horizontally polarized component and the vertically polarized component.

7. The identification unit The measurement device according to claim 6 , wherein the horizontally polarized component and the vertically polarized component are identified using a coherent detection method.

8. The measurement device according to claim 1 , further comprising a generating unit that generates point cloud data by combining the first distance and the second distance.

9. Transmitting a horizontally polarized beam and a vertically polarized beam toward a measurement target; receiving horizontally reflected light of the horizontally polarized beam reflected by the object to be measured and vertically reflected light of the vertically polarized beam reflected by the object to be measured; removing a vertically polarized component of the vertically reflected light when measuring a first distance to the measurement object using the horizontally polarized beam; removing a horizontally polarized component of the horizontally reflected light when measuring a second distance to the measurement object using the vertically polarized beam; measuring a first distance to the measurement target in accordance with a timing at which the horizontally reflected light is received; A measurement method in which a second distance to the measurement object is measured in accordance with a timing at which the perpendicularly reflected light is received.

10. Transmitting a horizontally polarized beam and a vertically polarized beam toward a measurement target; receiving horizontally reflected light of the horizontally polarized beam reflected by the object to be measured and vertically reflected light of the vertically polarized beam reflected by the object to be measured; removing a vertically polarized component of the vertically reflected light when measuring a first distance to the measurement object using the horizontally polarized beam; removing a horizontally polarized component of the horizontally reflected light when measuring a second distance to the measurement object using the vertically polarized beam; measuring a first distance to the measurement target in accordance with a timing at which the horizontally reflected light is received; a program that causes a computer to measure a second distance to the measurement object in accordance with a timing at which the vertically reflected light is received;

Images