JP6954494B2 - Laser radar device - Google Patents

Description

The present invention relates to a laser radar device.

Conventionally, a heterodyne detection type laser radar device is known as a laser radar device that measures wind speed by irradiating a laser beam into the atmosphere (see, for example, Patent Document 1). The heterodyne detection type laser radar device irradiates the atmosphere with laser light as transmitted light, and receives reflected light reflected by aerosol (minimal suspended particles such as dust in the atmosphere) as received light. The laser radar device combines the reference light and the received light by heterodyne detection to generate interference light, and converts the interference light into an electric signal. Then, the Doppler shift amount generated by the movement of the aerosol is obtained from the frequency spectrum obtained by Fourier transforming the electric signal, and the wind speed in the laser irradiation direction is measured from the Doppler shift amount.

WO2016 / 117159

When the transmitted light is transmitted to the object instead of the atmosphere by using the laser radar device, it is conceivable to measure the velocity of the object by receiving the reflected light from the object. For example, it is conceivable to measure the moving speed of the sea surface by irradiating the sea surface with a laser beam. However, since the received light received by the laser radar device described in Patent Document 1 includes not only the reflected light from the object but also the reflected light from the aerosol, the Doppler shift amount obtained by Fourier conversion is included in the Doppler shift amount. , Not only the speed of the object, but also the influence of the speed of the aerosol is included. As a result, when the velocity of the object is calculated from the Doppler shift amount, there is a problem that the velocity of the object cannot be calculated accurately due to the influence of the aerosol.
The present invention has been made to solve the above problems, and an object of the present invention is to obtain a laser radar device capable of calculating the speed of an object with higher accuracy.

The laser radar device according to the present invention has a light source unit that generates laser light in a band in which an object can be reflected, and a first polarization component and a first polarization component based on the laser light generated by the light source unit. The transmitted light including the second polarizing component is transmitted toward the object, the transmitted light receives the reflected light reflected by the object as the received light, and the first polarized light contained in the received light is first. Based on the difference between the detector, the first electric signal, and the second electric signal, which generates the electric signal of the above and generates the second electric signal from the second polarization component contained in the received light. It is equipped with a signal processing unit that calculates the speed of an object.

According to the laser radar device according to the present invention, the transmitted light including the first polarization component and the second polarization component different from the first polarization component is directed to the object based on the laser light generated by the light source unit. The transmitted light receives the reflected light reflected by the object as the received light, generates a first electric signal from the first polarized light component included in the received light, and generates a first electric signal, and a second included in the received light. By providing a detection unit that generates a second electric signal from a polarized light component and a signal processing unit that calculates the speed of an object based on the difference between the first electric signal and the second electric signal. Since the reflection in the aerosol has no polarization dependence, the reflected component from the aerosol can be removed by taking the difference between the first electric signal and the second electric signal, and the velocity of the object is calculated more accurately. be able to.

It is a block diagram which shows the structure of the laser radar apparatus in Embodiment 1. FIG. It is a block diagram which shows the structure of the signal processing part in Embodiment 1. FIG. It is a block diagram which shows the hardware structure of the signal processing part in Embodiment 1. FIG. FIG. 5 is a flowchart showing an operation of calculating the speed of an object by the laser radar device according to the first embodiment. It is explanatory drawing which shows the operation which the low frequency signal acquisition part in Embodiment 1 acquires an envelope. It is explanatory drawing which shows the operation which the difference calculation part in Embodiment 1 calculates a difference. It is explanatory drawing which shows the operation which the extraction part in Embodiment 1 extracts the reflection component from the sea surface from the 1st electric signal. It is a block diagram which shows the structure of the laser radar apparatus in Embodiment 2. FIG. It is a block diagram which shows the structure of the signal processing part in Embodiment 2. FIG. 5 is a flowchart showing an operation of calculating the speed of an object by the laser radar device according to the second embodiment. It is a block diagram which shows the structure of the laser radar apparatus in Embodiment 3. FIG. 5 is a flowchart showing an operation of calculating the speed of an object by the laser radar device according to the third embodiment. It is a block diagram which shows the structure of the laser radar apparatus in Embodiment 4. It is a block diagram which shows the structure of the signal processing part in Embodiment 4. FIG. 5 is a flowchart showing an operation of calculating the speed of an object by the laser radar device according to the fourth embodiment. It is explanatory drawing which shows the transmitted light which contains the 1st polarization component and the 2nd polarization component. It is explanatory drawing which shows the transmitted light which contains the 1st polarization component and the 2nd polarization component.

Embodiment 1.
The laser radar device 1 according to the first embodiment is derived from a first electric signal generated from a received light having a first polarized light component and a received light having a second polarized light component different from the first polarized light component. By calculating the velocity of the object based on the difference from the generated second electric signal, the influence from the aerosol can be reduced and the velocity of the object can be calculated.

FIG. 1 is a configuration diagram showing the configuration of the laser radar device 1 according to the first embodiment, and FIG. 2 is a configuration diagram showing the configuration of the signal processing unit 4 according to the first embodiment.

The laser radar device 1 shown in FIG. 1 has a light source unit 2 that generates laser light in a band in which an object can be reflected, and a first polarization component and a first polarization component based on the laser light generated by the light source unit. A transmitted light containing a second polarization component different from that of the object is transmitted toward the object, the transmitted light receives the reflected light reflected by the object as received light, and the first polarized component included in the received light is received. The difference between the detection unit 3 that generates the first electric signal from the light and generates the second electric signal from the second polarization component contained in the received light, the first electric signal, and the second electric signal. It is provided with a signal processing unit 4 for calculating the speed of an object based on the light.
In the present specification, based on the difference between the first electric signal and the second electric signal is not only based on the direct difference between the first electric signal and the second electric signal, but also the acquisition of the envelope, etc. It also includes being based on the difference between the first electric signal and the second electric signal after performing a predetermined process. In the first embodiment, the velocity of the object is calculated based on the difference between the first envelope and the second envelope, which will be described later.
As used herein, the transmitted light does not refer to only one pulse, but includes a plurality of pulses separated by time. In the following, the transmission pulse means a pulse included in the transmission light.
Further, in the present specification, the transmitted light including the first polarized light component and the second polarized light component is the transmission pulse 1011 in the first polarized state having the first polarized light component E1 as shown in FIG. And the case where the transmission pulse 1012 in the second polarized state having the second polarized component E2 is alternately transmitted with the passage of time, and the case where the first polarized component and the second polarized component are transmitted as shown in FIG. It means both when transmitting a transmitted pulse 1013 in a polarized state having both. In the first embodiment, as the transmission light including the first polarization component and the second polarization component, the transmission pulse 1011 in the first polarization state and the transmission pulse 1012 in the second polarization state shown in FIG. 16 are used for time. A case of alternately transmitting with the lapse of time will be described.
Further, the received light having the first polarization component is the reception obtained by receiving the reflected light in which the transmission pulse in the first polarized state having the first polarization component of the received light is reflected by the object. The received light which is light and has a second polarization component is obtained by receiving the reflected light in which the transmission pulse in the second polarized state having the second polarization component of the received light is reflected by the object. It is the received light. Similarly, in the interference light, the interference light having the first polarization component corresponds to the transmission pulse in the first polarization state, and the interference light having the second polarization component is the second polarization. It corresponds to the transmission pulse of the state.
The laser radar device 1 is configured as described above, and each part will be described in detail below.

The light source unit 2 generates laser light in a band in which the object can be reflected. Here, the object to be measured by the laser radar device 1 is one in which the reflected light has polarization dependence, such as a sea surface or a vehicle. In the following, it is assumed that the object is the sea surface, and the speed at which the sea surface moves, that is, the tidal current speed is calculated.
The laser light generated by the light source unit 2 is continuous light having a single frequency in a band where the sea surface can be reflected. For example, a semiconductor laser device or a solid-state laser device is used for the light source unit 2. Further, the polarization state of the laser light output from the light source unit 2 may be any one such as elliptically polarized light and randomly polarized light, but in the following, the laser light output from the light source unit 2 is in a linearly polarized state. It shall be.

The detection unit 3 transmits and transmits the transmitted light including the first polarization component and the second polarization component different from the first polarization component to the object based on the laser light generated by the light source unit 2. The reflected light reflected by the object is received as the received light, a first electric signal is generated from the first polarized light component contained in the received light, and a second polarized light component contained in the received light is used to generate a second electric signal. It generates an electric signal of.
The detection unit 3 in the first embodiment polarizes the laser light generated by the light source unit 2 so as to include the first polarization component and the second polarization component, and refers to the transmission light and the same polarization state as the transmission light. An optical control unit 5 that outputs light and a transmission / reception unit 6 that transmits the transmitted light output from the optical control unit 5 toward an object and receives the reflected light reflected by the object as received light. And the combine light unit 7 that generates interference light by combining the received light received by the transmission / reception unit 6 and the reference light output from the optical control unit 5, and the first electricity by converting the input interference light. It has an optical detection unit 8 that generates an electric signal including a signal and a second electric signal. Further, in the first embodiment, the first electric signal is an electric signal generated by converting the interference light having the first polarization component by the photodetector 8, and the second electric signal is the photodetector. It is an electric signal generated by converting the interference light having the second polarization component.

The optical control unit 5 polarizes the laser light generated by the light source unit 2 so as to include a first polarized light component and a second polarized light component, and transmits the first polarized light component and the second polarized light component. It outputs light and reference light in the same polarized state as the transmitted light. In the first embodiment, the optical control unit 5 has a polarization unit 51 that polarizes the laser light output by the light source unit 2, and a distribution unit 52 that distributes the laser light polarized by the polarization unit 51 into transmission light and reference light. And a modulation unit 53 that modulates the transmitted light distributed by the distribution unit 52.

The polarizing unit 51 polarizes the laser light generated by the light source unit 2 to generate a laser beam containing a first polarization component and a second polarization component. Specifically, the polarizing unit 51 in the first embodiment has a first polarization state in which the laser beam output by the light source unit 2 has a first polarization component, and a second polarization state different from the first polarization component. A second polarized state having a polarized component is alternately polarized with the passage of time. In order to increase the intensity difference between the first electric signal and the second electric signal, which will be described later, in the following, the first polarization state is a linearly polarized state having only the first polarization component, and the second polarization state is A linearly polarized state having only a second polarized component is used.
As the polarizing unit 51, for example, a wave plate, an optical fiber polarizing switch, or a Pockels cell is used. Further, the light source unit 2 and the polarizing unit 51 are connected by an optical fiber cable.
Further, when the polarization state of the laser light output from the light source unit 2 matches the first polarization state, the polarization unit 51 may be configured to transmit the light in the first polarization state as it is. That is, in the above, the fact that the polarizing unit 51 polarizes the laser light to the first polarization state means that the laser light output from the polarization unit 51 may be in the first polarization state, which is different from the first polarization state. It includes not only polarization from the state to the first polarized state, but also inputting the laser light of the first polarized state and outputting the laser light of the first polarized state as it is without changing the polarized state. This also applies to the second polarized state.

The distribution unit 52 distributes the laser light polarized by the polarization unit 51 into the transmission light and the reference light. In the first embodiment, the distribution unit 52 distributes the laser light polarized by the polarization unit 51 to the modulation unit 53 and the combine unit 7 at a predetermined ratio. Here, the laser light output to the modulation unit 53 is the transmission light, and the laser light output to the combiner unit 7 is the reference light.
As the distribution unit 52, for example, a branch mirror using an optical fiber coupler, a dielectric multilayer filter, or a beam splitter is used. Further, the polarizing unit 51 and the distribution unit 52 are connected by an optical fiber cable.

The modulation unit 53 modulates the transmitted light distributed by the distribution unit 52. In the first embodiment, the modulation unit 53 performs pulse modulation for converting continuous light into a pulse and frequency shift for shifting the frequency by a frequency shift amount with respect to the transmission light from the distribution unit 52 to generate a transmission pulse. .. Further, the pulse modulation is performed with a predetermined pulse width and pulse modulation frequency. The pulse width may be configured to correspond to the distance resolution and the pulse width corresponding to the desired distance resolution may be set by the user, or may be operated with a fixed pulse width set at the time of system design. Similarly, the frequency shift may be configured by the user, or may be configured to operate with a fixed frequency shift amount set at the time of system design.
Further, the polarization unit 51 and the modulation unit 53 have a polarization switching frequency indicating the frequency of switching the polarization to the first polarization state and the polarization to the second polarization state, and a pulse modulation frequency indicating the frequency of performing pulse modulation. By synchronizing the above, transmission pulses having different polarization states are generated for each pulse.
As the modulation unit 53, for example, an optical modulator including an electro-optical crystal or an acoustic-optical crystal is used, and the modulation unit 53 and the distribution unit 52 are connected by an optical fiber cable.
If the intensity of the transmitted light output from the modulation unit 53 is weak, an optical amplifier may be added after the modulation unit 53.

The transmission / reception unit 6 transmits the transmission light including the first polarization component and the second polarization component output from the optical control unit 5 toward the object, and receives the reflected light reflected by the object. It is received as light. In the first embodiment, the transmission / reception unit 6 has a transmission / reception separation unit 61 and a transmission / reception shared optical system 62.

The transmission / reception separation unit 61 outputs the transmission light input from the modulation unit 53 to the transmission / reception shared optical system 62, and outputs the reception light input from the transmission / reception shared optical system 62 to the combiner unit 7. For the transmission / reception separation unit 61, for example, an optical circulator in which a wave plate and a polarization beam splitter are combined is used, and the modulation unit 53 and the transmission / reception separation unit 61 are connected by an optical fiber cable.

The transmission / reception shared optical system 62 transmits the transmission light input from the transmission / reception separation unit 61 toward the object, receives the reflected light reflected by the object as the reception light, and outputs the transmission light to the transmission / reception separation unit 61. Is what you do. Here, the reflected light (received light) received by the transmission / reception shared optical system 62 includes not only the reflected component from the object but also the reflected component from the aerosol, and the reflected component from the object is the first. A reflection component in which the transmitted light having a polarization component is reflected by the object and a reflection component in which the transmission light having a second polarization component is reflected by the object are included. For the transmission / reception shared optical system 62, for example, an optical telescope or a camera lens is used. Further, the transmission / reception separation unit 61 and the transmission / reception shared optical system 62 are connected by an optical fiber cable.
In the first embodiment, since the transmitted light having the first polarization component and the transmitted light having the second polarization component are transmitted to the object using the same optical system, the optical paths of the respective transmitted lights are ambient. The time changes in the environment are consistent on a negligible scale, and the optical loss from the optical path is the same for both polarized light. This improves the accuracy when the signal processing unit 4 takes the difference between the first envelope and the second envelope.
Further, in the present invention, the transmitting optical system and the receiving optical system may be configured separately, but in the first embodiment, the transmitting optical system that transmits the transmitted light toward the object and the transmitting optical system from the object are used. Since the receiving optical system that receives the reflected light is collectively composed of one transmission / reception shared optical system, the optical axes of the transmitted light and the reflected light can be matched.

The combiner 7 generates interference light by combining the received light received by the transmitter / receiver 6 with the reference light output from the optical control unit 5. More specifically, since the received light received by the transmission / reception unit 6 includes a reflection component of the transmission light having a first polarization component and a transmission light having a second polarization component, the interference light generated by the combiner 7 is generated. Also includes interference light having a first polarization component and interference light having a second polarization component. Here, the interference light means an interference component of light generated by a combined wave. The combiner 7 in the first embodiment is configured to output two interference lights having phases 180 ° different from each other to the photodetector 8 according to the configuration of the photodetector 8.
As the combiner 7, for example, a branch mirror using a dielectric multilayer filter, a beam splitter, or an optical fiber coupler is used. Further, the distribution unit 52 and the combine unit 7 and the transmission / reception separation unit 61 and the combine unit 7 are connected by an optical fiber cable.

The photodetector 8 converts the interference light generated by the combiner 7 to generate an electric signal including a first electric signal and a second electric signal. Further, in the first embodiment, the first electric signal is an electric signal generated by the light detection unit 8 by converting the interference light having the first polarization component generated by the combiner unit 7. The electric signal is an electric signal generated by the light detection unit 8 by converting the interference light having the second polarization component generated by the combiner unit 7.

More specifically, the photodetector 8 converts the interference light generated by the combiner 7 into an analog electric signal, and the photodetector 81 and the photodetector 81 generate an analog electric signal. It has an A / D conversion unit 82 that converts a signal into a digital signal.

The photodetector 81 has a balanced receiver configuration and includes two light receiving elements made of photodiodes. Each light receiving element receives interference light having different phases output from the combiner 7, and the photodetector 81 generates an electric signal based on the difference in the output current of each light receiving element. With the above configuration, the photodetector 81 can reduce the noise caused by the light source unit 2. Further, the combiner 7 and the photodetector 81 are connected by an optical fiber cable.

The A / D converter 82 converts the electrical signal output from the photodetector 81 from an analog signal to a digital signal. In the first embodiment, the A / D conversion unit 82 outputs the electric signal converted into a digital signal to the low frequency signal acquisition unit 41 and the extraction unit 43. Further, the photodetector 81 and the A / D converter 82 are connected by an electric signal cable.

In FIG. 2, the signal processing unit 4 calculates the speed of the object based on the difference between the first electric signal and the second electric signal.

Further, the signal processing unit 4 in the first embodiment includes a low frequency signal acquisition unit 41 that acquires a low frequency signal from which a high frequency component is removed from the electric signal generated by the light detection unit 8, and a low frequency signal acquisition unit 41. The difference between the first low-frequency signal acquired from the first electric signal and the second low-frequency signal acquired by the low-frequency signal acquisition unit 41 from the second electric signal is the difference between the first electric signal and the above. The first electric signal is based on the difference calculation unit 42 calculated as the difference from the second electric signal, the difference calculated by the difference calculation unit 42, and the first electric signal generated by the light detection unit 8. It has an extraction unit 43 that generates an electric signal that extracts a reflection component from the object, and a speed calculation unit 44 that calculates the speed of the object using the electric signal extracted by the extraction unit 43.
Further, the A / D conversion unit 82 and the signal processing unit 4 are connected by an electric signal cable.

The low-frequency signal acquisition unit 41 acquires a low-frequency signal from which high-frequency components have been removed from the electric signal generated by the photodetector. The first low-frequency signal is a low-frequency signal acquired from the first electric signal, and the second low-frequency signal is a low-frequency signal acquired from the second electric signal.
In the first embodiment, the low frequency signal acquisition unit 41 acquires the envelope of the electric signal as the low frequency signal. Further, the first low frequency signal is the first envelope which is the envelope acquired from the first electric signal, and the second low frequency signal is the envelope acquired from the second electric signal. The second envelope. To get the envelope, for example, use the functions provided in each programming language.

The difference calculation unit 42 includes a first low-frequency signal acquired by the low-frequency signal acquisition unit 41 from the first electric signal and a second low-frequency signal acquired by the low-frequency signal acquisition unit 41 from the second electric signal. Is calculated as the difference between the first electric signal and the second electric signal. In the first embodiment, the difference calculation unit 42 calculates the difference between the first envelope and the second envelope. Further, the difference calculation unit in the first embodiment has a function of storing the first envelope until the second envelope is input and the difference is calculated after the first envelope is input. ..

The extraction unit 43 extracts the reflection component from the object from the first electric signal based on the difference calculated by the difference calculation unit 42 and the first electric signal generated by the light detection unit 8. Is to generate. In the first embodiment, the extraction unit 43 multiplies the difference calculated by the difference calculation unit 42 with the first electric signal generated by the photodetection unit 8 to obtain the first electric signal from the object. Extract the reflective components.
The difference calculation unit 42 and the extraction unit 43 remove the reflection component due to the aerosol from the interference light and extract the reflection component due to the sea surface according to the above configuration. This mechanism will be described in detail below.

The difference calculation unit 42 and the extraction unit 43 extract the reflection component by the sea surface from the electric signal generated by converting the interference light, whereas the reflection of the light by the sea surface has polarization dependence. It utilizes the fact that the reflection of light by the aerosol has no polarization dependence or has a small polarization dependence. For the sake of brevity, aerosol reflections are treated here as having no polarization dependence.
Since the reflection by the sea surface has polarization dependence, the received light received by the transmission / reception unit 6 and the interference light generated by the combiner 7 have different intensities due to the difference in the polarization state. That is, the received light and the interference light having the first polarization component and the reception light and the interference light having the second polarization component have an intensity difference. On the other hand, since the reflection from the aerosol has no polarization dependence, the reflected component from the aerosol is different in the polarization state between the received light received by the transmission / reception unit 6 and the interference light generated by the combiner 7. There is no difference in strength due to. That is, of the received light and the interference light having the first polarization component and the reception light and the interference light having the second polarization component, the reflection component from the aerosol has no difference in intensity. Therefore, if the difference between the first electric signal generated from the interference light having the first polarization component and the second electric signal generated from the interference light having the second polarization component is taken, the reflection from the aerosol is taken. The component is removed and only the reflected component from the sea surface remains. In the first embodiment, as a difference between the first electric signal and the second electric signal, a second envelope acquired from the first electric signal and a second electric signal acquired from the second electric signal are obtained. Use the difference from the envelope.
Specifically, as shown in FIG. 6, when the difference between the first envelope 101 and the second envelope 102 is taken, the obtained difference 103 has a zero reflection component from the aerosol and the sea surface. Only the reflection component from has a non-zero value.
Then, as shown in FIG. 7, when the obtained difference 103 is multiplied by the first electric signal 100, the difference 103 is obtained by multiplying because only the reflection component from the sea surface has a non-zero value. The electric signal 106 to be generated also has a non-zero value only in the time range corresponding to the reflected component from the sea surface. In this way, the difference calculation unit 42 and the extraction unit 43 reduce the influence of the aerosol on the electric signal obtained by the photodetection unit 8.
6 and 7 will be described in detail in the description of the operation of the laser radar device 1 described later.

The velocity calculation unit 44 calculates the velocity of the object by using the electric signal extracted by the extraction unit 43. In the first embodiment, the speed calculation unit 44 has a range bin division unit 441 that divides the electric signal extracted by the extraction unit 43 into a plurality of range bins, and a frequency spectrum for each range bin of the electric signal divided by the range bin division unit 441. It is provided with a frequency spectrum calculation unit 442 for calculating the frequency spectrum, and a Doppler speed calculation unit 443 for calculating the speed of the object from the Doppler shift amount of the frequency spectrum calculated by the frequency spectrum calculation unit 442.

The range bin dividing unit 441 divides the electric signal extracted by the extraction unit 43 into a plurality of range bins. Here, the range bin is a time range having a predetermined time width, and dividing the electric signal into the range bin means dividing the electric signal into predetermined time widths.

The frequency spectrum calculation unit 442 calculates the frequency spectrum for each range bin of the electric signal divided by the range bin division unit 441. The frequency spectrum calculation unit 442 according to the first embodiment performs FFT (Fast Fourier Transform) processing on the electric signal divided for each range bin.
Here, the frequency of the electric signal output from the light detection unit 8 is the sum of the frequency shift amount given by the modulation unit 53 and the Doppler shift amount corresponding to the speed of the object, and is calculated by the frequency spectrum calculation unit 442. The frequency spectrum has a peak value at the frequency value of the sum of the frequency shift amount and the Doppler shift amount.

The Doppler velocity calculation unit 443 calculates the velocity of the object from the Doppler shift amount of the frequency spectrum calculated by the frequency spectrum calculation unit 442. Since the frequency spectrum calculated by the frequency spectrum calculation unit 442 has a peak value at the frequency value of the sum of the frequency shift amount and the Doppler shift amount, the frequency shift amount is subtracted from the frequency value corresponding to the peak value of the frequency spectrum, and the Doppler shift amount is subtracted. By calculating the shift amount, the speed of the object can be calculated.

Each function of the signal processing unit 4 is realized by a computer. FIG. 3 is a configuration diagram showing an example of a hardware configuration of a computer that realizes the signal processing unit 4.
The hardware shown in FIG. 3 includes a processing device 1000 such as a CPU (Central Processing Unit), a storage device 1001 such as a ROM (Read Only Memory) and a hard disk, and an input interface unit 1002. Further, the processing device 1000 and the storage device 1001 are connected by an electric signal cable, and similarly, the processing device 1000 and the input interface unit 1002 are connected by an electric signal cable.

The low frequency signal acquisition unit 41, the difference calculation unit 42, the extraction unit 43, and the speed calculation unit 44 shown in FIG. 1 are realized by executing the program stored in the storage device 1001 on the processing device 1000. The input interface unit 1002 has a function of outputting an electric signal input from the outside to the processing device 1000, and particularly outputs an electric signal input from the detection unit 3 to the processing device 1000.
Further, the method of realizing each function of the signal processing unit 4 is not limited to the combination of the hardware and the program described above, and is realized by the hardware alone such as an LSI (Large Scale Integrated Circuit) in which the program is implemented in the processing device. Alternatively, some functions may be realized by dedicated hardware, and some may be realized by a combination of a processing device and a program.

As described above, the laser radar device 1 according to the first embodiment is configured.
Further, a polarization-retaining optical fiber cable is used for the optical fiber cable connecting each part of the light source unit 2 and the detection unit 3. When a polarization-retaining optical fiber cable is used to connect each part, the polarization state is maintained by matching the Fast axis and Slow axis of the polarization-retaining optical fiber cable with the direction of the first polarization component and the direction of the second polarization component, respectively. Light can be propagated as it is.

Next, the operation of the laser radar device 1 in the present embodiment will be described.
FIG. 4 is a flowchart showing an operation of calculating the speed of an object by the laser radar device 1 in the present embodiment.

When the laser radar device 1 starts the operation of calculating the speed of the object, the light source unit 2 outputs the laser beam in step S1. As described above, the object in the first embodiment is the sea surface, and the velocity of the sea surface is calculated. Further, the laser beam is continuous light having a single frequency in a band where the sea surface can be reflected.

Next, in step S2, the polarizing unit 51 polarizes the laser light output by the light source unit 2 in step S1 to the first polarized state. In the following, the first polarized light component will be referred to as an S polarized light component with respect to the sea surface, and the second polarized light component will be referred to as a P polarized light component with respect to the sea surface. Thereby, the intensity difference between the reflected light having the first polarization component and the reflected light having the second polarization component, and by extension, the intensity difference between the first electric signal and the second electric signal can be maximized.

Next, in step S3, the distribution unit 52 distributes the laser light polarized in the first polarized state by the polarization unit 51 to the transmission light and the reference light. The distribution unit 52 outputs the transmitted light to the modulation unit 53 and outputs the reference light to the combine unit 7.

Next, in step S4, the modulation unit 53 performs pulse modulation and frequency shift on the transmitted light distributed by the distribution unit 52 in step S3. The modulation unit 53 outputs the modulated transmission light to the transmission / reception separation unit 61.

Next, in step S5, the transmission / reception shared optical system 62 transmits the transmission light input via the transmission / reception separation unit 61 toward the sea surface.

Next, in step S6, the transmission / reception shared optical system 62 receives the transmission light reflected on the sea surface as reception light. The transmission / reception shared optical system 62 outputs the received received light to the transmission / reception separation unit 61.

Next, in step S7, the combiner 7 combines the received light input to the combiner 7 via the transmission / reception separation unit 61 with the reference light distributed by the distributor 52 to generate interference light. Generate. The combiner 7 outputs the generated interference light to the photodetector 81.

Next, in step S8, the photodetector 81 converts the interference light generated by the combiner 7 in step S7 to generate an analog electric signal. Further, the electric signal generated by the optical detector 81 is converted from an analog signal to a digital signal by the A / D conversion unit 82, and then output to the low frequency signal acquisition unit 41 and the extraction unit 43.
The electrical signal obtained in this step is the first electrical signal.

Next, in step S9, the low frequency signal acquisition unit 41 acquires a low frequency signal from the input electric signal. The low frequency signal obtained in this step is the first low frequency signal, i.e. the first envelope.
FIG. 5 is an explanatory diagram showing an operation in which the low frequency signal acquisition unit 41 acquires an envelope. In FIG. 5, the first electrical signal 100 is illustrated by a thin solid line, and the first envelope 101 is illustrated by a thick solid line. In FIG. 5, the low frequency signal acquisition unit 41 acquires the first envelope 101 from the first electric signal 100 input from the A / D conversion unit 82. Then, the low frequency signal acquisition unit 41 outputs the acquired first envelope 101 to the difference calculation unit 42. The difference calculation unit 42 stores the input first envelope 101 until the second envelope is input in a later step and the difference is calculated.

Next, in step S10, the polarizing unit 51 polarizes the laser light output by the light source unit 2 into the second polarized state. Here, the time interval from step S1 to step S10 is determined by a preset polarization switching frequency.

Subsequent operations from step S11 to step S17 are the same as the operations from step S3 to step S9, except that the polarization state of the light to be processed is different.

In step S11, the distribution unit 52 distributes the laser light polarized in the second polarization state by the polarization unit 51 to the transmission light and the reference light. The distribution unit 52 outputs the transmitted light to the modulation unit 53 and outputs the reference light to the combine unit 7.

Next, in step S12, the modulation unit 53 performs pulse modulation and frequency shift on the transmitted light distributed by the distribution unit 52 in step S3. The modulation unit 53 outputs the modulated transmission light to the transmission / reception separation unit 61.

Next, in step S13, the transmission / reception shared optical system 62 transmits the transmission light input via the transmission / reception separation unit 61 toward the sea surface.

Next, in step S14, the transmission / reception shared optical system 62 receives the transmission light reflected on the sea surface as reception light.

Next, in step S15, the combiner 7 combines the received light input to the combiner 7 via the transmission / reception separation unit 61 with the reference light distributed by the distributor 52 to generate interference light. do. The combiner 7 outputs the generated interference light to the photodetector 81.

Next, in step S16, the photodetector 81 converts the interference light generated by the combiner 7 in step S7 to generate an analog electric signal. Further, the electric signal generated by the photodetector 81 is converted from an analog signal to a digital signal by the A / D conversion unit 82, and then output to the signal processing unit 4.
The electrical signal obtained in this step is the second electrical signal.

Next, in step S17, the low frequency signal acquisition unit 41 acquires a low frequency signal from the input electric signal. The low frequency signal obtained in this step is the second low frequency signal, i.e. the second envelope.

Next, in step S18, the difference calculation unit 42 calculates the difference between the first envelope acquired in step S9 and the second envelope acquired in step S17.
FIG. 6 is an explanatory diagram showing an operation in which the difference calculation unit 42 calculates the difference. In FIG. 6, the first envelope 101 is shown by a solid line, the second envelope 102 is shown by a dotted line, and the difference 103 is shown by a alternate long and short dash line. When the second envelope 102 is input from the low frequency signal acquisition unit 41, the difference calculation unit 42 calculates the difference 103 from the first envelope 101 stored in advance. Since the reflection component from the aerosol is common to the first envelope 101 and the second envelope 102, the signal voltage becomes zero in the time range 104 in which the reflection component from the aerosol is received when the difference is taken. , Only the signal voltage in the time range 105 that received the reflected component from the sea surface takes a non-zero value. Then, the difference calculation unit 42 outputs the calculated difference 103 to the extraction unit 43.

Next, in step S19, the extraction unit 43 multiplies the difference calculated by the difference calculation unit 42 with the first electric signal input from the A / D conversion unit 82 to obtain the first electric signal from the sea surface. Extract the reflection component of.
FIG. 7 is an explanatory diagram showing an operation in which the extraction unit 43 extracts a reflected component from the sea surface from the first electric signal 100. In FIG. 7, the first electric signal 100 and the electric signal 106 from which only the reflection component from the sea surface is extracted are shown by a thin solid line, and the difference 103 is shown by a thick solid line.
The extraction unit 43 multiplies the first electric signal 100 input from the A / D conversion unit and the difference 103 calculated by the difference calculation unit 42 to acquire the electric signal 106 from which only the reflection component from the sea surface is extracted. The extraction unit 43 outputs the electric signal 106 extracted only from the reflected component from the sea surface to the range bin division unit 441.

Next, in step S20, the range bin dividing unit 441 divides the electric signal extracted by the extraction unit 43 in step S19 into a plurality of range bins.

Next, in step S21, the frequency spectrum calculation unit 442 performs FFT processing on the electric signal divided by the range bin division unit 441 in step S20, and calculates the frequency spectrum of the electric signal for each range bin.

Next, in step S22, the Doppler velocity calculation unit 443 calculates the velocity of the object from the Doppler shift amount of the frequency spectrum calculated by the frequency spectrum calculation unit 442 in step S21.

By the operation of the laser radar device 1 as described above, the reflected component from the aerosol can be removed by taking the difference between the first electric signal and the second electric signal, and the velocity of the object can be calculated more accurately. can do.

Further, the laser radar device 1 of the first embodiment transmits a transmission pulse in a first polarized state having a first polarized component and a transmission pulse in a second polarized state having a second polarized component. Therefore, one light detector can generate a first electric signal and a second electric signal. Further, since the transmission pulse in the first polarized state and the transmission pulse in the second polarized state are alternately transmitted with the passage of time, the transmission pulse in the first polarized state and the transmission pulse in the second polarized state are transmitted. The change in the surrounding environment when the pulse is transmitted is smaller than when the polarization state is switched for each of a plurality of transmission pulses, and the difference in optical loss between the two polarizations can be reduced.

Further, since the low frequency signal acquisition unit 41 is provided and the difference between the first low frequency signal from which the high frequency component has been removed and the second low frequency signal is calculated, the first electric signal and the second electric signal can be calculated. Even when the phases of the electric signals are not aligned, the difference in signal voltage can be obtained without being affected by fine time fluctuation components (high frequency components), and the reflected component from the aerosol can be removed.
Further, in the first embodiment, since the envelope is acquired as the low frequency signal, the low frequency is not set as in the case of acquiring the low frequency signal with a low-pass filter or the like. The signal can be acquired.

Hereinafter, a modified example of the laser radar device 1 according to the first embodiment will be described.

In the embodiment of the above operation, the configuration is such that the switching to the second polarization state is performed after the completion up to step S9, but if the interference light having the first polarization component is generated, the first In parallel with the operation related to the interference light having a polarized light component, the operation related to the light having a second polarized light component may be performed, and the first electric signal and the first envelope are acquired in steps S8 and S9. The operation of step S10 may be started in parallel with the operation to be performed.

The low-frequency signal acquisition unit 41 is configured to acquire the envelope as a low-frequency signal, but the envelope is acquired in order to remove the high-frequency component from the electric signal. For example, a low-pass filter may be provided or a moving average may be obtained to remove high-frequency components. Alternatively, as in the fourth embodiment described later, a configuration using a photodetector having a slow response may be used.

The difference calculation unit 42 is configured to calculate the difference between the first envelope and the second envelope, but by calculating the difference, the reflected component from the aerosol is ignored with respect to the reflected component from the object. Other configurations may be used as long as the value can be made as small as possible. For example, if the time variation of the first electric signal and the second electric signal can be made uniform by calibration in the time direction, the first after calibration is used. The difference between the electric signal of 1 and the electric signal of the second may be calculated.

The extraction unit 43 is configured to extract the reflection component from the object by multiplying the difference calculated by the difference calculation unit 42 with the first electric signal input from the A / D conversion unit 82. Other configurations may be used as long as the reflective component from the object can be extracted. For example, for the first electric signal, a conversion is performed in which the time range in which the difference value is greater than or equal to a predetermined threshold value remains the original value, and the value in the time range in which the difference value is less than the threshold value is set to zero. Therefore, the reflection component from the object may be extracted.
Further, the electric signal to be multiplied by the difference is not limited to the first electric signal, and may be a second electric signal. Alternatively, the extraction unit 43 extracts the reflected component of the object from both the first electric signal and the second electric signal, and the velocity calculation unit 44 averages the velocities calculated from the respective extracted electric signals. The speed as the final calculation result may be calculated.

In the transmission / reception unit 6, the transmission optical system for transmitting the transmission light and the reception optical system for receiving the reception light are configured by one transmission / reception shared optical system 62, but the transmission optical system and the reception optical system are included. It may be composed of separate optical systems. In this case, it is not necessary to provide the transmission / reception separation unit 61 in front of the optical system.
Further, the transmission / reception shared optical system 62 may have a scanning mechanism for controlling the transmission direction of the transmission light. Alternatively, by providing a plurality of transmission / reception shared optical systems 62, transmission light may be transmitted in a plurality of directions at one time. With the above configuration, the moving direction of the object can be estimated more easily.

The difference calculation unit 42 calculates the difference between the first envelope obtained from the first electric signal and the second envelope obtained from the second electric signal, and the light detection unit 8 generates electricity. Since it is expected that the signal has an intensity difference due to the polarization dependence of the laser radar device 1 itself, calibration is performed so that the intensity difference in the time range excluding the reflection component from the object becomes zero. You may.

In the merging operation in the merging unit 7, when the polarizations of the reference light and the received light do not match, the generation efficiency of the interference light decreases, but in the first embodiment, the reference light is also transmitted by the polarizing unit 51. Since the light is polarized in the same polarization state as the above, the polarizations of the reference light and the received light are almost the same, and the interference light can be obtained with high generation efficiency. Further, when the polarizations of the reference light and the received light do not match, the generation efficiency of the interference light decreases, but the non-interference light, that is, the non-interference component of the combined wave light is used during the balanced detection in the photodetector 8. Since it is canceled, there is no problem in performing the operation of calculating the speed of the object.

Further, although the polarizing unit 51 is provided in the front stage of the distribution unit 52, it may be provided in another position as long as the transmitted light and the reference light can be polarized. For example, in the rear stage of the distribution unit 52 and the modulation unit 53. A total of two polarizing portions may be provided in the front stage, in the rear stage of the transmission / reception separation unit 61 and in the front stage of the transmission / reception shared optical system 62, and in the rear stage of the distribution unit 52 and in the front stage of the combiner unit 7. When the polarizing unit is provided in the rear stage of the transmission / reception separation unit 61 and in the front stage of the transmission / reception shared optical system 62, the received light is also polarized in the same polarization state as the transmission light, so that an excess polarization component can be removed.

The polarization section 51 and the modulation section 53 are configured to synchronize the polarization switching and the pulse modulation by making the polarization switching frequency and the pulse modulation frequency equal to each other, but the polarization section 51 and the modulation section 53 operate in synchronization with each other. If possible, the present invention is not limited to this configuration. For example, when the polarization unit 51 switches the polarization, a signal indicating that the polarization has been switched is transmitted to the modulation unit 53, and the modulation unit 53 operates based on this signal. The polarization unit 51 and the modulation unit 53 may be configured to operate in synchronization with each other. Further, the laser radar device 1 may further include a control unit that performs various controls, and the polarizing unit 51 and the modulation unit 53 may operate in synchronization with each other based on the control signal output by the control unit.

Further, although the optical control unit 5 switches the polarization state for each pulse, the polarization state may be switched for each plurality of pulses by setting the pulse modulation frequency to an integral multiple of the polarization switching frequency.

Further, although the Doppler speed calculation unit 443 is configured to calculate the speed of the object for each pulse, it is also possible to perform incoherent integration of a plurality of pulses to improve the signal-to-noise ratio and then calculate the speed. good.

Further, each part of the signal processing unit 4 may be mounted by an analog circuit. For example, the extraction unit 43 may be mounted by an analog circuit. In this case, the A / D conversion unit 82 is provided after the extraction unit 43 and before the speed calculation unit 44.

Further, although each of the light source unit 2 and the detection unit 3 is connected by an optical fiber cable, it may be connected by using a space propagation type transmission line.

Embodiment 2.
Next, Embodiment 2 of the present invention will be described.

FIG. 8 is a configuration diagram showing the configuration of the laser radar device 1 according to the second embodiment.
Further, FIG. 9 is a configuration diagram showing the configuration of the signal processing unit 40 according to the second embodiment.

In the first embodiment, the polarizing unit 51 provided in the laser radar device 1 has a first polarization state having a first polarization component for the laser light output by the light source unit 2, and the first polarization component. The second polarized state having a different second polarized component was alternately polarized with the passage of time.
On the other hand, the polarization unit 501 in the second embodiment polarizes the laser light output by the light source unit 2 into a polarized state having both a first polarization component and a second polarization component.
That is, in the first embodiment, the detection unit 3 alternately transmits the transmission pulse in the first polarized state and the transmission pulse in the second polarized state with the passage of time. In the second embodiment, the detection unit 3 transmits a transmission pulse having both a first polarization component and a second polarization component.
Therefore, the main difference from the first embodiment is the polarization section 501 and the polarization separation section 9.
As the polarizing unit 501, for example, a wave plate, an optical fiber polarizing switch, and a Pockels cell are used as in the first embodiment.

Further, the laser radar device 1 according to the second embodiment separates the input light into light in a first polarized state having a first polarized light component and light in a second polarized state having a second polarized light component. A polarization separating unit 9 is provided. Here, the polarization separation unit 9 in the second embodiment is provided in the rear stage of the combine unit 7 and in the front stage of the light detection unit 8, and the interference light generated by the combine unit 7 is used as the interference light in the first polarized state. And the second polarized light are separated into the interference light.
Similar to the first embodiment, the first polarized light state is a linearly polarized light state having only the first polarized light component, and the second polarized light state is a linearly polarized light state having only the second polarized light component.
For the polarization separating unit 9, for example, a polarization beam splitter or a fiber polarization coupler is used.

Further, the light detection unit 80 in the second embodiment converts the interference light having the first polarization component separated by the polarization separation unit 9 to generate a first electric signal, and the first polarization light detection unit 810. And a second polarization light detection unit 820 that converts interference light having a second polarization component separated by the polarization separation unit 9 to generate a second electric signal.

The first polarization light detection unit 810 includes a first polarization light detector 811 that converts interference light having a first polarization component to generate an analog first electric signal, and a first polarization light detector. It has a first polarization A / D conversion unit 812 that converts the first electric signal generated by 811 from an analog signal to a digital signal. Further, the first polarization photodetector 811 has a balanced receiver configuration including two light receiving elements, similarly to the photodetector 81 in the first embodiment.
The second polarization light detection unit 820 is a second polarization light detector 821 that converts interference light having a second polarization component to generate an analog second electric signal, and a second polarization light detector. It has a second polarization A / D conversion unit 822 that converts a second electric signal generated by 821 from an analog signal to a digital signal. Further, the second polarization photodetector 821 has a balanced receiver configuration including two light receiving elements, similarly to the first polarization photodetector 811.

Further, the signal processing unit 40 according to the second embodiment includes a low frequency signal acquisition unit 401 that acquires a low frequency signal from which a high frequency component is removed from the electric signal generated by the light detection unit 80, and a low frequency signal acquisition unit 401. The difference between the first low-frequency signal acquired from the first electric signal and the second low-frequency signal acquired by the low-frequency signal acquisition unit from the second electric signal is the difference between the first electric signal and the second electric signal. From the first electric signal, the target is based on the difference calculation unit 402 calculated as the difference from the electric signal, the difference calculated by the difference calculation unit 402, and the first electric signal generated by the light detection unit 80. It has an extraction unit 403 that generates an electric signal that extracts a reflection component from an object, and a speed calculation unit 44 that calculates the speed of an object using the electric signal extracted by the extraction unit 403.

Similar to the first embodiment, the low frequency signal acquisition unit 401 removes high frequency components from the electric signal generated by the photodetector 80 to acquire the low frequency signal. In the first embodiment, the input destination of the electric signal is the A / D conversion unit 82, whereas in the second embodiment, the input destination of the electric signal is the first polarization A / D conversion unit 812. It is an A / D conversion unit 822 for the second polarization, which is different at first glance, but this is a configuration in which the photodetector 8 has only the photodetector 81, whereas the photodetector 80 detects the light for the first polarization. It is a formal difference due to the provision of two photodetectors, the photodetector 811 and the photodetector 821 for the second polarization, and the input electric signal and the operation performed on the input electric signal are the same as those in the first embodiment. be.
Further, similarly to the first embodiment, the low frequency signal acquisition unit 401 in the second embodiment also acquires the envelope as a low frequency signal.

Similar to the first embodiment, the difference calculation unit 402 uses the first low-frequency signal acquired by the low-frequency signal acquisition unit 401 from the first electric signal and the low-frequency signal acquisition unit 401 from the second electric signal. The difference from the acquired second low frequency signal is calculated as the difference between the first electric signal and the second electric signal.
In the first embodiment, since the first envelope is input to the difference calculation unit 42 and then the second envelope is input, the difference calculation unit 42 is the first input first. The configuration was such that the envelope was stored until the difference was calculated, but in the second embodiment, since the first envelope and the second envelope are input to the difference calculation unit 402 almost at the same time, the difference calculation unit 42 does not have to memorize the first envelope for a long time. In the second embodiment, the difference calculation unit 402 inputs the envelope that was previously input to the difference calculation unit 402 among the first envelope and the second envelope, and the other envelope is input. The configuration is such that the difference is temporarily stored until it is calculated.

Similar to the first embodiment, the extraction unit 403 extracts the object from the first electric signal based on the difference calculated by the difference calculation unit 402 and the first electric signal generated by the light detection unit 80. It generates an electric signal by extracting the reflected component from. The extraction unit 403 in the second embodiment uses the first electric signal input from the first polarization A / D conversion unit 812, but is different from the first embodiment as in the low frequency signal acquisition unit 401. Is only the difference in the input destination, and the input electric signal and the operation performed on the input electric signal are the same as those in the first embodiment.

Other configurations are the same as those in the first embodiment.

Next, the operation of the laser radar device 1 according to the second embodiment will be described.
FIG. 9 is a flowchart showing an operation of calculating the speed of an object by the laser radar device 1 according to the second embodiment.

When the laser radar device 1 starts the operation of calculating the speed of the object, the light source unit 2 outputs the laser beam in step S201. Here, it is assumed that the object in the second embodiment is also the sea surface as in the first embodiment, and the laser radar device 1 calculates the speed of the sea surface.

Next, in step S202, the polarization unit 501 polarizes the laser light output by the light source unit 2 into a polarized state having both a first polarization component and a second polarization component. Also in the second embodiment, as in the first embodiment, the first polarized light component is an S polarized light component with respect to the sea surface, and the second polarized light component is a P polarized light component with respect to the sea surface.
Further, the polarized state having both the first polarized component and the second polarized component described above is a linearly polarized state in which the amplitudes of the S polarized component and the P polarized component are equal and the phases of the S polarized component and the P polarized component are synchronized. Suppose that As a result, it is possible to increase the intensity difference of the reflected component from the object in the first electric signal and the second electric signal while reducing the influence of the reflected component from the aerosol.

Further, as in the first embodiment, a polarization-retaining optical fiber cable is used as the optical fiber cable connecting each of the light source unit 2 and the detection unit 3. In this case, since the effective refractive index differs between the Fast axis and the Slow axis, the relative phases of the first polarization component and the second polarization component fluctuate, and the polarization state of the transmitted light emitted from the transmission / reception shared optical system 62 changes. It can change from linearly polarized light to circularly polarized light or elliptically polarized light. However, since the amplitudes of the first polarized light component and the second polarized light component do not fluctuate, there is no problem in the operation of calculating the velocity of the object.

The operation from step S203 to step S207 is the same as the operation from step S3 to step S7 in the first embodiment.
In step S203, the distribution unit 52 distributes the laser light polarized by the polarization unit 501 to the transmission light and the reference light. The distribution unit 52 outputs the transmitted light to the modulation unit 53 and outputs the reference light to the combine unit 7.

Next, in step S204, the modulation unit 53 performs pulse modulation and frequency shift on the transmitted light distributed by the distribution unit 52 in step S203. The modulation unit 53 outputs the modulated transmission light to the transmission / reception separation unit 61.

Next, in step S205, the transmission / reception shared optical system 62 transmits the transmission light input via the transmission / reception separation unit 61 toward the sea surface.

Next, in step S206, the transmission / reception shared optical system 62 receives the transmission light reflected on the sea surface as reception light. The transmission / reception shared optical system 62 outputs the received received light to the transmission / reception separation unit 61.

Next, in step S207, the combiner 7 combines the received light input to the combiner 7 via the transmission / reception separation unit 61 with the reference light distributed by the distributor 52 to generate interference light. do. The combiner 7 outputs the generated interference light to the polarization separation section 9.

Next, in step S208, the polarization separating unit 9 separates the interference light generated by the combining unit 7 into the interference light in the first polarization state and the interference light in the second polarization state. The polarization separation unit 9 outputs the interference light in the first polarization state to the first polarization photodetector 811 and outputs the interference light in the second polarization state to the second polarization photodetector 821.

Next, in step S209, the first polarization photodetector 811 converts the interference light in the first polarization state separated by the polarization separation unit 9 in step S208, and generates an analog first electric signal. The first polarization A / D conversion unit 812 converts the first electric signal generated by the first polarization photodetector 811 from an analog signal to a digital signal, and outputs the first electric signal to the low frequency signal acquisition unit 401 and the extraction unit 403. do.

Further, in parallel with the operation of step S209, in step S210, the second polarization photodetector 821 converts the interference light in the second polarization state separated by the polarization separation unit 9 in step S208, and the analog second Generates an electrical signal. Further, the second polarization A / D conversion unit 822 converts the second electric signal generated by the second polarization photodetector 821 from an analog signal to a digital signal, and outputs the second electric signal to the low frequency signal acquisition unit 401.

In step S211 the low frequency signal acquisition unit 401 acquires the first envelope from the first electric signal generated in step S209, and acquires the second envelope from the second electric signal. The 1st envelope and the 2nd envelope are output to the difference calculation unit 402.

The operation from step S212 to step S216 in the second embodiment is the same as the operation from step S18 to step S22 in the first embodiment.

Next, in step S212, the difference calculation unit 402 calculates the difference between the first envelope and the second envelope acquired in step S211. The difference calculation unit 402 outputs the acquired difference to the extraction unit 403.

In step S213, the extraction unit 403 multiplies the difference calculated by the difference calculation unit 402 with the first electric signal input from the first polarization A / D conversion unit 812 to obtain the first electric signal. Extract the reflected component from the sea surface.

Next, in step S214, the range bin dividing unit 441 divides the electric signal extracted by the extraction unit 403 in step S213 into a plurality of range bins.

Next, in step S215, the frequency spectrum calculation unit 442 performs FFT processing on the electric signal divided by the range bin division unit 441 in step S214, and calculates the frequency spectrum of the electric signal for each range bin.

Next, in step S216, the Doppler velocity calculation unit 443 calculates the velocity of the object from the Doppler shift amount of the frequency spectrum calculated by the frequency spectrum calculation unit 442 in step S215.

By operating the laser radar device 1 as described above, the reflected component from the aerosol can be removed by taking the difference between the first electric signal and the second electric signal, and the velocity of the object can be calculated more accurately. can do.

In the second embodiment, since the transmitted light having the first polarized light component and the transmitted light having the second polarized light component are overlapped and simultaneously transmitted as one transmitted light, the light of both polarized light passes through the same optical path. However, the optical loss can be matched with the bipolarized light as compared with the laser radar device 1 in the first embodiment.

Further, according to the laser radar device 1 in the second embodiment, since the first electric signal and the second electric signal can be acquired at the same time, the speed of the object can be determined from the laser radar device 1 in the first embodiment. It can be calculated quickly.

Hereinafter, a modified example of the laser radar device 1 according to the second embodiment will be described.

The polarization separation unit 9 is provided after the combiner 7 and in front of the light detection unit 80, and is configured to separate the interference light into the interference light in the first polarization state and the interference light in the second polarization state. A total of two polarization separation units are provided in the rear stage of the distribution unit 52 and the front stage of the combine unit 7 and in the rear stage of the transmission / reception separation unit 61 and the front stage of the combine unit 7, and the reference light and the received light are each first. The reference light in the polarized state and the reference light in the second polarized state, and the received light in the first polarized state and the received light in the second polarized state may be separated.

Similar to the first embodiment, the low frequency signal acquisition unit 401 may have another configuration as long as the high frequency component can be removed from the input electric signal, for example, by providing a low-pass filter or obtaining a moving average. , The configuration may be such that the high frequency component is removed.

Similar to the first embodiment, the difference calculation unit 402 is configured to calculate the difference between the first envelope and the second envelope, but the reflection component from the aerosol is an object by calculating the difference. Other configurations may be used as long as the value can be made negligibly small with respect to the reflection component from, for example, when the time variation of the first electric signal and the second electric signal can be made uniform by calibration in the time direction. May be configured to calculate the difference between the first electrical signal and the second electrical signal after calibration.

Similar to the first embodiment, in the transmission / reception unit 6, the transmission optical system for transmitting the transmission light and the reception optical system for receiving the reception light are configured by one transmission / reception shared optical system 62, but for transmission. The optical system and the receiving optical system may be configured as separate optical systems. In this case, it is not necessary to provide the transmission / reception separation unit 61 in front of the optical system.
Further, the transmission / reception shared optical system 62 may have a scanning mechanism for controlling the transmission direction of the transmission light. Alternatively, by providing a plurality of transmission / reception shared optical systems 62, transmission light may be transmitted in a plurality of directions at one time. With the above configuration, the moving direction of the object can be estimated more easily.

Similar to the first embodiment, the difference calculation unit 402 may have a function of performing calibration so that the intensity difference in the time range excluding the reflection component from the object becomes zero.

Similar to the first embodiment, the polarizing unit 501 may be provided at another position as long as the transmitted light can be polarized, for example, the rear stage of the distribution unit 52 and the front stage of the modulation unit 53, or the transmission / reception separation unit 61. A total of two polarizing units may be provided, one in the rear stage and in the front stage of the transmission / reception shared optical system, and one in the rear stage of the distribution unit 52 and in the front stage of the combiner unit 7. Further, when the polarizing unit 501 is provided in the subsequent stage of the transmission / reception separation unit 61 and in the front stage of the transmission / reception shared optical system 62, the received light is also polarized in the same polarization state as the transmission light to remove the excess polarization component. Can be done.

Similar to the first embodiment, the Doppler velocity calculation unit 443 does not calculate the velocity of the object for each pulse, but incoherently integrates a plurality of pulses to improve the signal-to-noise ratio and then increase the velocity. It may be a configuration to be calculated.

Similar to the first embodiment, each part of the signal processing unit 40 may be mounted by an analog circuit. For example, up to the extraction unit 403 may be mounted by an analog circuit. In this case, each A / D conversion unit is provided after the extraction unit 403 and before the speed calculation unit 44.

Similar to the first embodiment, each part of the light source unit 2 and the detection unit 3 is connected by an optical fiber cable, but may be connected by using a space propagation type transmission line.

Similar to the first embodiment, the extraction unit 403 multiplies the difference calculated by the difference calculation unit 402 with the first electric signal input from the first polarization A / D conversion unit 812 to obtain the object from the object. Although the configuration is such that the reflection component of the above is extracted, another configuration may be used as long as the reflection component from the object can be extracted. For example, for the first electric signal, a conversion is performed in which the time range in which the difference value is greater than or equal to a predetermined threshold value remains the original value, and the value in the time range in which the difference value is less than the threshold value is set to zero. Therefore, the reflection component from the object may be extracted.
Further, the electric signal to be multiplied by the difference is not limited to the first electric signal, and may be a second electric signal. Alternatively, the extraction unit 403 extracts the reflected component of the object from both the first electric signal and the second electric signal, and the velocity calculation unit 44 averages the velocities calculated from the respective extracted electric signals. The speed as the final calculation result may be calculated.

Embodiment 3.
Next, Embodiment 3 of the present invention will be described.

FIG. 11 is a configuration diagram showing the configuration of the laser radar device 1 according to the third embodiment.
In the first embodiment and the second embodiment, the transmitted light in the first polarized state and the transmitted light in the second polarized state are transmitted and received using the same transmission / reception shared optical system.
On the other hand, the laser radar device 1 in the third embodiment transmits and receives the transmitted light in the first polarized state and the transmitted light in the second polarized state by using different transmission / reception shared optical systems.
Therefore, the main difference from the first and second embodiments is the optical control unit 500 and the transmission / reception unit 60.
The above configuration will be described in detail below.

The detection unit 3 in the third embodiment polarizes the laser light generated by the light source unit 2 so as to include the first polarization component and the second polarization component, and applies the transmission light and the same polarization as the transmission light. Transmission / reception in which the optical control unit 500 that outputs the reference light and the transmitted light output from the optical control unit 500 are transmitted toward the object, and the transmitted light receives the reflected light reflected by the object as the received light. The first unit 60 converts the received light received by the transmission / reception unit 60 and the reference light output from the optical control unit 500 to generate interference light, and the input interference light is converted into the first unit. It has an optical detection unit 80 that generates an electric signal including the electric signal of the above and a second electric signal.

Similar to the first and second embodiments, the optical control unit 500 polarizes the laser light generated by the light source unit 2 so as to include the first polarized light component and the second polarized light component, and obtains the first polarized light component. It outputs the transmitted light including the second polarized light component and the reference light having the same polarization state as the transmitted light.
Further, in the third embodiment, the optical control unit 500 distributes the first distribution unit 5001 that distributes the laser light output by the light source unit 2 to the reference light and the transmission light, and the transmission light distributed by the first distribution unit 5001. The modulation unit 5002 to be modulated, the second distribution unit 5003 that distributes the transmission light modulated by the modulation unit 5002 to the first transmission light and the second transmission light, and the first distribution unit 5003 distributed by the second distribution unit 5003. The first polarizing unit 5004 for transmission light that polarizes the transmitted light to the first polarization state having the first polarization component, and the second transmission light distributed by the second distribution unit 5003 have the second polarization component. A second polarizing unit 5005 for transmission light that is polarized to a second polarization state, and a third distribution unit 5006 that distributes the reference light distributed by the first distribution unit 5001 to the first reference light and the second reference light. , The first polarizing unit 5007 for reference light that polarizes the first reference light distributed by the third distribution unit 5006 to the first polarization state, and the second reference light distributed by the third distribution unit 5006. It includes a second polarization section 50008 for reference light that is polarized to the polarization state of 2.

The first distribution unit 5001 distributes the laser light output by the light source unit 2 to the reference light and the transmission light, and like the distribution unit 52 in the first embodiment, for example, an optical fiber coupler or a dielectric multilayer film. A branch mirror using a filter and a beam splitter are used.

The modulation unit 5002 modulates the transmission light distributed by the first distribution unit 5001, and similarly to the modulation unit 53 in the first embodiment, the transmission light is pulse-modulated and frequency-shifted. Similar to the modulation unit 53 in the first embodiment, as the modulation unit 5002, for example, an optical modulator including an electro-optical crystal or an acoustic optical crystal is used.

The second distribution unit 5003 distributes the transmission light modulated by the modulation unit 5002 to the first transmission light and the second transmission light, and like the first distribution unit 5001, for example, an optical fiber coupler or the like. A branch mirror and a beam splitter using a dielectric multilayer filter are used.

The first polarization unit 5004 for transmission light polarizes the first transmission light distributed by the second distribution unit 5003 into a first polarization state having a first polarization component, and is polarized in the first embodiment. Similar to the part 51, for example, a wave plate, an optical fiber polarizing switch, and a Pockels cell are used. The first transmitted light includes a plurality of transmitted pulses in a first polarized state having a first polarized component.

The second polarization unit 5005 for transmission light polarizes the second transmission light distributed by the second distribution unit 5003 into a second polarization state having a second polarization component, and is the first polarization for transmission light. Similar to the part 5004, for example, a wave plate, an optical fiber polarizing switch, and a Pockels cell are used. The second transmitted light includes a plurality of transmitted pulses in a second polarized state having a second polarized component.

Similar to the first and second embodiments, in the following, the first polarization state to be polarized by the first polarization unit 5004 for transmission light is a linearly polarized state having only the first polarization component, and the second polarization for transmission light. The second polarized state to be polarized by the unit 5005 is a linearly polarized state having only the second polarized component.

The third distribution unit 5006 distributes the reference light distributed by the first distribution unit 5001 to the first reference light and the second reference light, and is the same as the first distribution unit 5001 and the second distribution unit 5003. For example, a branch mirror or a beam splitter using an optical fiber coupler or a dielectric multilayer film filter is used.

The first polarization unit 5007 for reference light polarizes the first reference light distributed by the third distribution unit 5006 into the first polarization state, and is similar to the first polarization unit 5004 for transmission light, for example. , Wave plates, optical fiber polarizing switches, and Pockels cells are used.

The second polarization unit 5008 for reference light polarizes the second reference light distributed by the third distribution unit 5006 into the second polarization state, and is similar to the first polarization unit 5004 for transmission light, for example. , Wave plates, optical fiber polarizing switches, and Pockels cells are used.

The transmission / reception unit 60 transmits the transmission light including the first polarization component and the second polarization component output from the light control unit 500 toward the object, and the transmitted light reflects the reflected light by the object. It is received as received light.
In the third embodiment, the transmission / reception unit 60 transmits the first transmission light polarized by the first polarization unit 5004 for transmission light toward the object, and the first transmission light is reflected by the object. The first transmission / reception unit 610 that receives the reflected light of 1 as the first reception light and the second transmission light polarized by the second polarization unit 5005 for transmission light are transmitted toward the object, and the second transmission is performed. Includes a second transmitter / receiver 620 that receives the second reflected light reflected by the object as the second received light.

The first transmission / reception unit 610 transmits the first transmission light input from the first polarization unit 5004 for transmission light toward the object, and the first reflected light reflected by the object is the first reception light. It has a first transmission / reception separation unit 611 and a first transmission / reception shared optical system 612. That is, the first transmission / reception unit 610 has a function as a first transmission unit that transmits the first transmission light toward the object and a function as a first reception unit that receives the first reception light.
The first transmission / reception separation unit 611 outputs the first transmission light input from the first polarization unit 5004 for transmission light to the first transmission / reception shared optical system, and the first transmission / reception separation unit 611 is input from the first transmission / reception shared optical system 612. The received light is output to the first confluence unit 701, and similarly to the transmission / reception separation unit 61 in the first embodiment, for example, an optical circulator in which a wave plate and a polarizing beam splitter are combined is used.
The first transmission / reception shared optical system 612 transmits the first transmission light input from the first transmission / reception separation unit 611 toward the object, and the first reflected light reflected by the object is the first reception light. The first received light is output to the first transmission / reception separation unit 611. As in the transmission / reception shared optical system 62 in the first embodiment, for example, an optical telescope or a camera lens is used.

The second transmission / reception unit 620 transmits the second transmission light input from the second polarization unit 5005 for transmission light toward the object, and the second reflected light reflected by the object is the second reception light. It has a second transmission / reception separation unit 621 and a second transmission / reception shared optical system 622. That is, the second transmission / reception unit 620 has a function as a second transmission unit that transmits the second transmission light toward the object and a function as a second reception unit that receives the second reception light.
The second transmission / reception separation unit 621 outputs the second transmission light input from the second polarization unit 5005 for transmission light to the second transmission / reception shared optical system, and the second transmission / reception separation unit 621 is input from the second transmission / reception shared optical system 622. The received light is output to the second confluence unit 702, and like the first transmission / reception separation unit 611, for example, an optical circulator in which a wave plate and a polarizing beam splitter are combined is used.
The second transmission / reception shared optical system 622 transmits the second transmission light input from the second transmission / reception separation unit 621 toward the object, and the second reflected light reflected by the object is the second reception light. The second received light is output to the second transmission / reception separation unit 621. Similar to the first transmission / reception shared optical system 612, for example, an optical telescope or a camera lens is used.

The combined wave unit 70 generates interference light by combining the received light received by the transmitting / receiving unit 60 with the reference light output from the optical control unit 500.
In the third embodiment, the combiner 70 combines the first received light received by the first transmitter / receiver 610 and the first reference light distributed by the third distributor 5006 to form the first interference light. The first interference unit 701 that generates the light, the second reception light received by the second transmission / reception unit 620, and the second reference light distributed by the third distribution unit 5006 are combined to generate the second interference light. Includes a second confluence section 702 to be generated.

The first combiner unit 701 generates the first interference light by combining the first received light received by the first transmission / reception unit 610 and the first reference light distributed by the third distribution unit 5006. A branch mirror, a beam splitter, and an optical fiber coupler using a dielectric multilayer film filter are used, as in the case of the combine 7 in the first embodiment.

The second combing unit 702 combines the second received light received by the second transmitting / receiving unit 620 with the second reference light distributed by the third splitting unit 5006 to generate the second interference light. A branch mirror, a beam splitter, and an optical fiber coupler using a dielectric multilayer film filter are used, as in the case of the combine 7 in the first embodiment.

The photodetector 80 converts the first interference light to generate a first electric signal, and also converts the second interference light to generate a second electric signal, and inputs the interference light. It is the same as the photodetector 80 in the second embodiment except that the tip is different.
The first polarization light detection unit 810 inputs the first interference light from the first confluence unit and generates the first electric signal. Further, the second polarization light detection unit 820 inputs the second interference light from the second confluence unit and generates a second electric signal.

Other configurations are the same as those of the first and second embodiments. In particular, the signal processing unit 40 is the same as the signal processing unit 40 in the second embodiment.

Next, the operation of the laser radar device 1 according to the third embodiment will be described.
FIG. 12 is a flowchart showing the operation of the laser radar device 1 in the third embodiment to calculate the speed of the object.

When the laser radar device 1 starts the operation of calculating the speed of the object, the light source unit 2 outputs the laser beam in step S301. Here, the object in the third embodiment is also the sea surface as in the first and second embodiments, and the laser radar device 1 calculates the velocity of the sea surface. Further, also in the third embodiment, as in the first and second embodiments, the first polarized light component is an S polarized light component with respect to the sea surface, and the second polarized light component is a P polarized light component with respect to the sea surface.

Next, in step S302, the first distribution unit 5001 distributes the laser light output by the light source unit 2 to the transmission light and the reference light. The first distribution unit 5001 outputs the transmitted light to the modulation unit 5002 and outputs the reference light to the third distribution unit 5006.

Next, in step S303, the reference light distributed in step S302 is distributed to the first reference light and the second reference light by the third distribution unit 5006. The third distribution unit 5006 outputs the first reference light to the first polarization unit 5007 for reference light, and outputs the second reference light to the second polarization unit 5008 for reference light.

Next, in step S304, the first polarization unit 5007 for reference light polarizes the first reference light distributed in step S302 into the first polarized state, and the polarized first reference light is the first combined wave. Output to unit 701.

Further, in parallel with step S304, in step S305, the second polarization unit 5008 for reference light polarized the second reference light distributed in step S303 into the second polarized state and polarized the second reference. The light is output to the second combined wave section 702.

The following operations from step S306 to step S310 are performed in parallel with the above operations from step S303 to step S304, and the following operations from step S306 to step S316 are from the above steps S303 to S305. It is done in parallel with the operation. Further, the following operations from step S308 to step S313 are performed in parallel with the following operations from step S314 to step S319.

In step S306, the modulation unit 5002 performs pulse modulation and frequency shift on the transmitted light distributed by the first distribution unit 5001 in step S302. The modulation unit 5002 outputs the modulated transmission light to the second distribution unit 5003.

Next, in step S307, the second distribution unit 5003 distributes the transmitted light modulated in step S306 to the first transmitted light and the second transmitted light. The second distribution unit 5003 outputs the first transmitted light to the first polarization unit 5004 for transmission light, and outputs the second transmission light to the second polarization unit 5005 for transmission light.

Next, in step S308, the first polarization unit 5004 for transmission light polarizes the first transmission light distributed in step S304 into the first polarization state, and the polarized first transmission light is separated by the first transmission / reception. Output to unit 611.

Next, in step S309, the first transmission / reception shared optical system 612 transmits the first transmission light input via the first transmission / reception separation unit 611 toward the sea surface.

Next, in step S310, the first transmission / reception shared optical system 612 receives the first reflected light reflected on the sea surface as the first reception light. The first transmission / reception shared optical system 612 outputs the received first reception light to the first transmission / reception separation unit 611.

Next, in step S311, the first merging unit 701 combines the first received light input via the first transmission / reception separating unit 611 with the first reference light polarized in step S304, and the first Generates 1 interference light.

Next, in step S312, the first polarization photodetector 811 converts the first interference light generated by the first confluence unit 701 in step S311 to generate an analog first electric signal. The first polarization A / D conversion unit 812 converts the first electric signal generated by the first polarization photodetector 811 from an analog signal to a digital signal and outputs it to the signal processing unit 40.

Next, in step S313, the low frequency signal acquisition unit 401 acquires the first envelope from the first electric signal acquired in step S312. The low frequency signal acquisition unit 401 outputs the acquired first envelope to the difference calculation unit 402.

The operation from step S314 to step S319 is the same as the operation from step S308 to step S313 except that the polarization state of the light to be handled is different. Further, as described above, the operations from step S314 to step S319 are performed in parallel with the operations from step S308 to step S319.

In step S314, the second polarization unit 5005 for transmission light polarized the second transmission light distributed in step S304 into the second polarized state, and the polarized second transmission light was transferred to the second transmission / reception separation unit 621. Output to.

Next, in step S315, the second transmission / reception shared optical system 622 transmits the second transmission light input via the second transmission / reception separation unit 621 toward the sea surface.

Next, in step S316, the second transmission / reception shared optical system 622 receives the second reflected light reflected on the sea surface as the second reception light. The second transmission / reception shared optical system 622 outputs the received second reception light to the second transmission / reception separation unit 621.

Next, in step S317, the second interference unit 702 combines the second received light input via the second transmission / reception separation unit 621 with the second reference light polarized in step S305, and the second wave is combined. Generates 2 interference lights.

Next, in step S318, the second polarization photodetector 821 converts the second interference light generated by the second wave unit 702 in step S317 to generate an analog second electric signal. The second polarization A / D conversion unit 822 converts the second electric signal generated by the second polarization photodetector 821 from an analog signal to a digital signal and outputs the second electric signal to the signal processing unit 40.

Next, in step S319, the low frequency signal acquisition unit 401 acquires a second envelope from the second electric signal acquired in step S318. The low frequency signal acquisition unit 401 outputs the acquired second envelope to the difference calculation unit 402.

The operation from the next step S320 to step S324 is the same as the operation from step S212 to step S216 of the second embodiment.

Next, in step S320, the difference calculation unit 402 calculates the difference between the first envelope acquired in step S313 and the second envelope acquired in step S319. The difference calculation unit 402 outputs the acquired difference to the extraction unit 403.

In step S321, the extraction unit 403 multiplies the difference calculated by the difference calculation unit 402 with the first electric signal input from the A / D conversion unit, so that the reflection component from the sea surface from the first electric signal is multiplied. Is extracted.

Next, in step S322, the range bin dividing unit 441 divides the electric signal extracted by the extraction unit 43 in step S321 into a plurality of range bins.

Next, in step S323, the frequency spectrum calculation unit 442 performs FFT processing on the electric signal divided by the range bin division unit 441 in step S322, and calculates the frequency spectrum of the electric signal for each range bin.

Next, in step S324, the Doppler velocity calculation unit 443 calculates the velocity of the object from the Doppler shift amount of the frequency spectrum calculated by the frequency spectrum calculation unit 442 in step S323.

By the operation of the laser radar device 1 as described above, the reflected component from the aerosol can be removed by taking the difference between the first electric signal and the second electric signal, and the velocity of the object can be calculated more accurately. can do.

Further, according to the laser radar device 1 in the third embodiment, as in the second embodiment, the first electric signal and the second electric signal can be acquired at the same time, so that the speed of the object can be adjusted. It can be calculated faster than the laser radar device 1 in the first embodiment.

Further, in the third embodiment, a transmission unit for transmitting a transmission pulse in a first polarized state having a first polarized component and a transmission unit for transmitting a transmission pulse in a second polarized state having a second polarized component are transmitted. Since the unit is provided separately, it is possible to propagate the transmitted light while maintaining the linearly polarized state when propagating the polarization-retaining optical fiber cable.

Hereinafter, a modified example of the laser radar device 1 according to the third embodiment will be described.

The optical control unit 500 has a first polarization unit 5004 for transmission light and a second polarization unit 5005 for transmission light after the second distribution unit 5003, and has a first polarization unit 5007 for reference light and a second polarization for reference light. Although the unit 5008 is provided after the third distribution unit 5006, the position where each polarization unit is provided is not limited to this as long as the transmission light and the reference light can be polarized, for example, the first polarization unit for transmission light. The 5004 and the first polarizing unit 5007 for reference light may be collectively provided as the first light source unit in the rear stage of the light source unit 2 and in the front stage of the first distribution unit 5001.

The first transmission / reception unit 610 and the second transmission / reception unit 620 are configured such that the transmission optical system for transmitting the transmission light and the reception optical system for receiving the reception light are each composed of one transmission / reception shared optical system. The optical system and the receiving optical system may be configured as separate optical systems. In this case, it is not necessary to provide a transmission / reception separation unit in front of the optical system.
Further, the first transmission / reception shared optical system 612 and the second transmission / reception shared optical system 622 may have a scanning mechanism for controlling the transmission direction of the transmitted light. Alternatively, by providing a plurality of transmission / reception shared optical systems, the transmission light may be transmitted in a plurality of directions at one time. With the above configuration, the moving direction of the object can be estimated more easily.

Similar to the first and second embodiments, the low-frequency signal acquisition unit 401 may have another configuration as long as the high-frequency component can be removed from the input electric signal. For example, a low-pass filter is provided or a moving average is obtained. As a result, the configuration may be such that the high frequency component is removed.

Similar to the first and second embodiments, the difference calculation unit 402 is configured to calculate the difference between the first envelope and the second envelope, but the reflection component from the aerosol is calculated by calculating the difference. Other configurations may be used as long as the value can be made negligibly small with respect to the reflected component from the object. For example, the time variation of the first electric signal and the second electric signal can be made uniform by calibration in the time direction. If possible, the difference between the first electrical signal and the second electrical signal after calibration may be calculated.

Similar to the first and second embodiments, the extraction unit 403 may have another configuration as long as the reflective component from the object can be extracted. For example, for the first electric signal, a time range in which the difference is greater than or equal to a predetermined threshold value is left as the original value, and a value in the time range in which the difference is less than the threshold value is converted to zero. It may be configured to extract the reflection component from.

Similar to the first and second embodiments, the difference calculation unit 402 may have a function of performing calibration so that the intensity difference in the time range excluding the reflection component from the object becomes zero.

Similar to the first and second embodiments, the Doppler speed calculation unit 443 does not calculate the speed of the object for each pulse, but incoherently integrates a plurality of pulses to improve the signal-to-noise ratio. It may be configured to calculate the speed.

Similar to the first and second embodiments, each part of the signal processing unit 40 may be mounted by an analog circuit. For example, the extraction unit 403 may be mounted by an analog circuit. In this case, the A / D conversion unit is provided after the extraction unit 403 and before the speed calculation unit 44.

Similar to the first and second embodiments, the light source unit 2 and the detection unit 3 are connected by an optical fiber cable, but may be connected by using a space propagation type transmission line.

Similar to the first and second embodiments, the extraction unit 403 multiplies the difference calculated by the difference calculation unit 402 with the first electric signal input from the first polarization A / D conversion unit 812. Although the configuration is such that the reflection component from the object is extracted, another configuration may be used as long as the reflection component from the object can be extracted. For example, for the first electric signal, a conversion is performed in which the time range in which the difference value is greater than or equal to a predetermined threshold value remains the original value, and the value in the time range in which the difference value is less than the threshold value is set to zero. Therefore, the reflection component from the object may be extracted.
Further, the electric signal to be multiplied by the difference is not limited to the first electric signal, and may be a second electric signal. Alternatively, the extraction unit 403 extracts the reflected component of the object from both the first electric signal and the second electric signal, and the velocity calculation unit 44 averages the velocities calculated from the respective extracted electric signals. The speed as the final calculation result may be calculated.

Embodiment 4.
Next, Embodiment 4 of the present invention will be described.

FIG. 13 is a configuration diagram showing the configuration of the laser radar device 1 according to the fourth embodiment.
Further, FIG. 14 is a configuration diagram showing the configuration of the signal processing unit 400 according to the fourth embodiment.
In the first to third embodiments, the first electric signal is an electric signal generated by converting the interference light having the first polarization component, and the second electric signal is the interference light having the second polarization component. It was an electric signal generated by converting. On the other hand, in the fourth embodiment, the first electric signal is an electric signal generated by converting the received light having the first unwavering polarized light component, and the second electric signal is , Is an electrical signal generated by converting received light having a second polarization component that is not combined.
Therefore, the main difference from the first to third embodiments is the received light distribution unit 10 and the light detection unit 800.
The above configuration will be described in detail below.

The detection unit 3 in the fourth embodiment polarizes the laser light generated by the light source unit 2 so as to include the first polarization component and the second polarization component, and obtains the first polarization component and the second polarization component. The optical control unit 5 that outputs the transmitted light including the A transmission / reception unit 6 that receives the reflected reflected light as reception light, a reception light distribution unit 10 that distributes the reception light received by the transmission / reception unit 6 to a first reception light and a second reception light, and an optical control unit 5. The reference light output from the light source and the first received light distributed by the reception light distribution unit 10 are combined to generate interference light, and the interference light generated by the wave combination unit 700 is converted. The interference light detection unit 8010 that generates an electric signal and the second received light distributed by the received light distribution unit 10 are converted to generate an electric signal including the first electric signal and the second electric signal. It has a light detection unit 800 including a reception light detection unit 8020.

The optical control unit 5 and the transmission / reception unit 6 in the fourth embodiment are the same as the optical control unit 5 and the transmission / reception unit 6 in the first embodiment. Further, the combiner 700 in the fourth embodiment is the same as the combiner 700 in the first embodiment except that the input destination of the received light is different.
The combiner 700 in the fourth embodiment combines the reference light output from the optical control unit 5 and the first received light distributed by the received light distribution unit 10 to generate interference light.

The reception light distribution unit 10 distributes the reception light received by the transmission / reception unit 6 to the interference reception light and the difference reception light. In the fourth embodiment, the received light distribution unit 10 distributes the received light received by the transmission / reception unit 6 to the combiner 700 and the received light detection unit 8020 at a predetermined ratio. Here, the received light output to the combiner 700 is the interference received light, and is for performing heterodyne detection. Further, the received light output to the received light detection unit 8020 is the difference receiving light, which is for acquiring the difference between the first electric signal and the second electric signal and reducing the influence from the aerosol.
As the receiving light distribution unit 10, for example, a branch mirror or a beam splitter using an optical fiber coupler or a dielectric multilayer filter is used as in the distribution unit 52 in the first embodiment.

The photodetector 800 converts the interference light detection unit 8010 that converts the interference light generated by the combiner 700 to generate an electric signal and the difference reception light distributed by the reception light distribution unit 10 to generate electricity. It includes a received light detection unit 8020 that generates a signal.
Here, the interference light detection unit 8010 converts the interference light generated by the combiner 700 into an analog electric signal, and the interference light detector 8011 and the electric signal generated by the interference light detector 8011 are analog. It has an A / D conversion unit 8012 for interference light that converts a signal into a digital signal.
Further, the received photodetector 8020 includes a received photodetector 8021 that converts the interference received light distributed by the received light distribution unit 10 to generate an analog electric signal, and an electric signal generated by the received photodetector 8021. 8022 for receiving light, which converts an analog signal into a digital signal. Here, as the received photodetector 8021, a detector having a slow response in detecting light is used. As a result, the electric signal generated by the received photodetector 8021 has the high frequency component removed, and a low frequency signal can be obtained. That is, the received light detection unit 8020 in the fourth embodiment has the same function as the low frequency signal acquisition unit in the first to third embodiments.
In the following, for the sake of distinction, the electric signal generated by converting the interference light by the interference light detection unit 8010 is called a beat signal, and the electric signal generated by converting the reception light by the reception light detection unit 8020 is low. Called a frequency signal. Further, the beat signal generated by converting the interference light having the first polarization component is called the first beat signal, and the beat signal generated by converting the interference light having the second polarization component is called the second beat signal. It is called the beat signal of.
Similarly, the low frequency signal generated by converting the received light having the first polarization component is called the first low frequency signal, and the low frequency generated by converting the received light having the second polarization component is called the first low frequency signal. The signal is called a second low frequency signal.

The difference calculation unit 4002 included in the signal processing unit 400 in the fourth embodiment calculates the difference using the electric signal output by the received light A / D conversion unit 8022. That is, the difference calculation unit 4002 calculates the difference between the first low frequency signal and the second low frequency signal as the difference between the first electric signal and the second electric signal. Further, the difference calculation unit 4002 is the first input until the difference is calculated, in the same manner that the difference calculation unit 42 in the first embodiment stores the first envelope until the difference is calculated. Memorize low frequency signals.

Further, the extraction unit 4003 in the fourth embodiment multiplies the first beat signal input from the interference light A / D conversion unit 8012 and the difference input from the difference calculation unit 4002 to obtain the first beat. It extracts the reflected component from the sea surface from the signal, and has the same function as the extraction unit of the first to third embodiments.

Other configurations are the same as those in the first embodiment.
Next, the operation of the laser radar device 1 according to the fourth embodiment will be described.
FIG. 15 is a flowchart showing the operation of the laser radar device 1 in the fourth embodiment to calculate the speed of the object.

The operation from step S401 to step S406 is the same as the operation from step S1 to step S6 of the laser radar device 1 in the first embodiment.

When the laser radar device 1 starts the operation of calculating the speed of the object, the light source unit 2 outputs the laser beam in step S401. Here, the object in the fourth embodiment is also the sea surface as in the first to the third embodiments, and the velocity of the sea surface is calculated.

Next, in step S402, the polarizing unit 51 polarizes the laser beam output by the light source unit 2 in step S401 into a first polarized state having a first polarization component. Also in the fourth embodiment, as in the first to third embodiments, the first polarized light component is an S polarized light component with respect to the sea surface, and the second polarized light component is a P polarized light component with respect to the sea surface.

Next, in step S403, the distribution unit 52 distributes the laser light polarized by the polarization unit 51 to the transmission light and the reference light. The distribution unit 52 outputs the transmitted light to the modulation unit 53 and outputs the reference light to the combine unit 700.

Next, in step S404, the modulation unit 53 performs pulse modulation and frequency shift on the transmitted light distributed by the distribution unit 52 in step S403. The modulation unit 53 outputs the modulated transmission light to the transmission / reception separation unit 61.

Next, in step S405, the transmission / reception shared optical system 62 transmits the transmission light input via the transmission / reception separation unit 61 toward the sea surface.

Next, in step S406, the transmission / reception shared optical system 62 receives the transmission light reflected on the sea surface as reception light. The transmission / reception shared optical system 62 outputs the received received light to the transmission / reception separation unit 61.

Next, in step S407, the reception light distribution unit 10 distributes the reception light input via the transmission / reception separation unit 61 into the interference reception light and the difference reception light. That is, the reception light distribution unit 10 outputs the interference reception light to the combiner 700 and outputs the difference reception light to the reception light detection unit 8020.

Next, in step S408, the combiner 700 combines the reference light distributed by the distribution unit 52 in step S403 with the interference received light distributed by the reception light distribution unit 10 in step S407 to generate interference light. Generate.

Next, in step S409, the interference light detector 8011 converts the interference light generated by the combiner 700 in step S408 to generate an analog beat signal. Further, the beat signal generated by the interference light detector 8011 is converted from an analog signal to a digital signal by the interference light A / D conversion unit 8012, and then output to the extraction unit 4003.

In parallel with step S408 and step S409, in step S410, the received photodetector 8021 converts the differential received light distributed in step S407 to generate an analog low frequency signal. Further, the low frequency signal generated by the received photodetector 8021 is converted from an analog signal to a digital signal by the received light A / D conversion unit 8022, and then output to the difference calculation unit 4002.

Next, in step S411, the polarization unit 51 polarizes the laser light output by the light source unit 2 into a second polarization state having a second polarization component. Similar to the first embodiment, the time interval from step S402 to step S411 is determined by a preset polarization switching frequency.

The operation from step S412 to step S418 is the same as the operation from step S403 to step S409 except that the polarization state of the light to be processed is different. Further, the operations from step S412 to step S419 are the same as the operations from step S403 to step S410, except that the polarization state of the light to be processed is different.

Next, in step S412, the distribution unit 52 distributes the laser light polarized by the polarization unit 51 to the transmission light and the reference light. The distribution unit 52 outputs the transmitted light to the modulation unit 53 and outputs the reference light to the combine unit 700.

Next, in step S413, the modulation unit 53 performs pulse modulation and frequency shift on the transmitted light distributed by the distribution unit 52 in step S3. The modulation unit 53 outputs the modulated transmission light to the transmission / reception separation unit 61.

Next, in step S414, the transmission / reception shared optical system 62 transmits the transmission light input via the transmission / reception separation unit 61 toward the sea surface.

Next, in step S415, the transmission / reception shared optical system 62 receives the transmission light reflected on the sea surface as reception light. The transmission / reception shared optical system 62 outputs the received received light to the transmission / reception separation unit 61.

Next, in step S416, the received light distribution unit 10 distributes the received light received in step S406 into the interference received light and the difference received light. That is, the reception light distribution unit 10 outputs the interference reception light to the combiner 700 and outputs the difference reception light to the reception light detection unit 8020.

Next, in step S417, the combiner 700 combines the reference light distributed by the distribution unit 52 in step S412 with the difference reception light distributed by the reception light distribution unit 10 in step S416 to generate interference light. Generate.

Next, in step S418, the interference light detector 8011 converts the interference light generated by the combiner 700 in step S417 to generate an analog beat signal. Further, the beat signal generated by the interference light detector 8011 is converted from an analog signal to a digital signal by the interference light A / D conversion unit 8012, and then output to the extraction unit 4003.

In parallel with step S417 and step S418, in step S419, the received photodetector 8021 converts the differential received light distributed in step S416 to generate an analog low frequency signal. Further, the low frequency signal generated by the received photodetector 8021 is converted from an analog signal to a digital signal by the received light A / D conversion unit 8022, and then output to the difference calculation unit 4002.

The operation from the next step S420 to step S424 is the same as the operation from step S18 to step S22 in the first embodiment.

Next, in step S420, the difference calculation unit 4002 calculates the difference between the first low-frequency signal acquired in step S410 and the second low-frequency signal acquired in step S419. Then, the difference calculation unit 4002 outputs the calculated difference to the extraction unit 4003.

Next, in step S421, the extraction unit 4003 multiplies the difference calculated by the difference calculation unit 4002 in step S420 by the first beat signal input from the interference light A / D conversion unit 8012. The reflected component from the sea surface is extracted from the beat signal of 1. The extraction unit 4003 outputs a beat signal extracted only from the sea surface component to the range bin division unit.

Next, in step S422, the range bin dividing unit 441 divides the beat signal extracted by the extraction unit 43 in step S421 into a plurality of range bins.

Next, in step S423, the frequency spectrum calculation unit 442 performs FFT processing on the electric signal divided by the range bin division unit 441 in step S422, and calculates the frequency spectrum of the electric signal for each range bin.

Next, in step S424, the Doppler velocity calculation unit 443 calculates the velocity of the object from the Doppler shift amount of the frequency spectrum calculated by the frequency spectrum calculation unit 442 in step S423.

By the operation of the laser radar device 1 as described above, the reflected component from the aerosol can be removed by taking the difference between the first electric signal and the second electric signal, and the velocity of the object can be calculated more accurately. can do.

Further, according to the laser radar device 1 in the fourth embodiment, a low frequency signal can be acquired in parallel with the acquisition of the beat signal.

Hereinafter, a modified example of the laser radar device 1 according to the fourth embodiment will be described.

The received light detector 8020 is configured to generate a low frequency signal by having a received photodetector 8021 which is a slow response photodetector, but instead of the received light detector 8021, light having a normal response speed is used. A detector may be used and a low-pass filter may be provided after the photodetector.

Further, although the received light detection unit 8020 is used as a low frequency signal acquisition unit for acquiring a low frequency signal, a digital circuit is installed after the A / D conversion unit 8022 for received light as in the first to third embodiments. A low frequency signal acquisition unit may be provided in the above.

The polarizing unit 51 included in the optical control unit 5 is the same as the polarizing unit 51 of the first embodiment, but the same as the polarizing unit 501 of the second embodiment may be provided. In this case, each of the interference light detection unit 8010 and the reception light detection unit 8020 detects the light having the first light detection unit and the light having the second polarization component for detecting the light having the first polarization component. The configuration includes a second light detection unit for this purpose.

Similar to the first to third embodiments, the extraction unit 4003 multiplies the difference calculated by the difference calculation unit 4002 with the first beat signal input from the interference light A / D conversion unit 8012 to obtain an object. Although the configuration is such that the reflection component from the object is extracted, another configuration may be used as long as the reflection component from the object can be extracted. For example, for the first beat signal, the object is converted by performing a conversion in which the time range in which the difference is greater than or equal to a predetermined threshold value remains the original value and the value in the time range in which the difference is less than the threshold value is set to zero. It may be configured to extract the reflection component from.

Similar to the first to third embodiments, in the transmission / reception unit 6, the transmission optical system for transmitting the transmission light and the reception optical system for receiving the reception light are configured by one transmission / reception shared optical system 62. The transmitting optical system and the receiving optical system may be configured as separate optical systems. In this case, it is not necessary to provide the transmission / reception separation unit 61 in front of the optical system.
Further, the transmission / reception shared optical system 62 may have a scanning mechanism for controlling the transmission direction of the transmission light. Alternatively, by providing a plurality of transmission / reception shared optical systems 62, transmission light may be transmitted in a plurality of directions at one time. With the above configuration, the moving direction of the object can be estimated more easily.

Similar to the first to third embodiments, the difference calculation unit 4002 is configured to calculate the difference between the first envelope and the second envelope, but the reflection component from the aerosol is calculated by calculating the difference. Other configurations may be used as long as the value can be made negligibly small with respect to the reflected component from the object. For example, the time variation of the first electric signal and the second electric signal can be made uniform by calibration in the time direction. If possible, the difference between the first electrical signal and the second electrical signal after calibration may be calculated.

Similar to the first to third embodiments, the difference calculation unit 4002 calculates the difference between the first low frequency signal and the second low frequency signal, but the electric signal generated by the photodetection unit 800 is a laser. Since it is expected that there is an intensity difference due to the polarization dependence of the radar device 1 itself, calibration may be performed so that the intensity difference in the time domain not including the object becomes zero.

Further, as in the first and second embodiments, the polarizing unit 51 is provided in front of the distribution unit 52, but other positions may be provided as long as the transmitted light and the reference light can be polarized, for example. A total of two polarized light, one in the rear stage of the distribution unit 52 and the front stage of the modulation unit 53, one in the rear stage of the transmission / reception separation unit 61 and the front stage of the transmission / reception shared optical system, and one in the rear stage of the distribution unit 52 and the front stage of the combiner 700. A configuration may be provided in which a portion is provided. When the polarizing unit 51 is provided in the rear stage of the transmission / reception separation unit 61 and in the front stage of the transmission / reception shared optical system 62, the received light is also polarized in the same polarization state as the transmission light, so that an excess polarization component can be removed. ..

Further, as in the first embodiment, the polarization unit 51 and the modulation unit 53 are configured to synchronize the polarization and the pulse modulation by making the polarization switching frequency and the pulse modulation frequency equal to each other. However, the polarization unit 51 and the modulation unit are configured. Other configurations may be used as long as the 53 can operate in synchronization. For example, when the polarizing unit 51 switches the polarization, a signal indicating that the polarization has been switched is transmitted to the modulation unit 53, and this configuration is used. A configuration may be configured in which the polarizing unit 51 and the modulation unit 53 operate in synchronization with each other by the modulation unit 53 operating based on the signal. Further, the laser radar device 1 may further include a control unit that performs various controls, and the polarizing unit 51 and the modulation unit 53 may operate in synchronization with each other based on the control signal output by the control unit.

Further, as in the first to third embodiments, the optical control unit 5 switches the polarization state for each pulse, but by setting the pulse modulation frequency to an integral multiple of the polarization switching frequency, the polarized light is polarized for each of a plurality of pulses. It may be configured to switch the state.

Further, similarly to the first to third embodiments, the Doppler speed calculation unit 443 is configured to calculate the speed of the object for each pulse, but a plurality of pulses are incoherently integrated to improve the signal-to-noise ratio. Then, the speed may be calculated.

Further, as in the first to third embodiments, each part of the signal processing unit 400 may be mounted by an analog circuit. For example, the extraction unit 4003 may be mounted by an analog circuit. In this case, the A / D conversion unit is provided after the extraction unit 4003 and before the speed calculation unit 44.

Further, as in the first to third embodiments, the light source unit 2 and the detection unit 3 are connected by an optical fiber cable, but may be connected by using a space propagation type transmission line.

Similar to the first to third embodiments, the extraction unit 4003 multiplies the difference calculated by the difference calculation unit 4002 with the first beat signal input from the interference light A / D conversion unit 8012 to obtain an object. Although the configuration is such that the reflection component from the object is extracted, another configuration may be used as long as the reflection component from the object can be extracted. For example, for the first beat signal, a conversion is performed in which the time range in which the difference value is greater than or equal to a predetermined threshold value remains the original value, and the value in the time range in which the difference value is less than the threshold value is set to zero. Therefore, the reflection component from the object may be extracted.
Further, the electric signal to be multiplied by the difference is not limited to the first beat signal, and may be a second beat signal. Alternatively, the extraction unit 4003 extracts the reflection component of the object from both the first beat signal and the second beat signal, and the velocity calculation unit 44 averages the velocity calculated from each extracted beat signal. The speed as the final calculation result may be calculated.

In the first to fourth embodiments, the object of the laser radar device 1 is the sea surface, but other substances may be used as long as the reflected light is a substance having polarization dependence, for example, an artificial object such as a vehicle or an airplane. It can also be used for.

The laser radar device according to the present invention is suitable for use in a radar system that measures information on an object such as speed.

1 Laser radar device, 2 Light source unit, 3 Detection unit, 4,40,400 Signal processing unit, 41,401 Low frequency signal acquisition unit, 42,402,4002 Difference calculation unit, 43,403,4003 Extraction unit, 44 Speed Calculation unit, 441 range bin division unit, 442 frequency spectrum calculation unit, 443 Doppler speed calculation unit, 5,50,500 optical control unit, 51,501 polarization unit, 52 distribution unit, 53,5002 modulation unit, 5001 first distribution unit , 5003 2nd distribution unit, 5004 1st polarization unit for transmission light, 5005 2nd polarization unit for transmission light, 5006 3rd distribution unit, 5007 1st polarization unit for reference light, 5008 2nd polarization unit for reference light, 6 , 60 Transmission / reception unit, 61 Transmission / reception separation unit, 62 Transmission / reception shared optical system, 610 1st transmission / reception unit, 620 2nd transmission / reception unit, 611 1st transmission / reception separation unit, 612 1st transmission / reception shared optical system, 621 2nd transmission / reception separation unit, 622 2nd transmission / reception shared optical system, 7,70 confluence unit, 701 1st confluence unit, 702 2nd confluence unit, 8,80,800 optical detector unit, 81 optical detector, 82 A / D converter, 810 1st polarization light detection unit, 811 1st polarization light detector, 812 1st polarization A / D conversion unit, 820 2nd polarization light detection unit, 821 2nd polarization light detector, 822 2nd A / D conversion unit for polarization, 8010 interference light detector, 8011 interference light detector, 8012 A / D conversion unit for interference light, 8020 reception light detector, 8021 reception light detector, 8022 A / D conversion for reception light Unit, 9 Polarization separator, 10 Received light distributor, 100 1st electrical signal, 101 1st optic line, 102 2nd optic line, 103 Difference, 104 Time range in which the reflection component from the aerosol was received. , 105 Time range in which the reflected component from the sea surface was received, 106 Electrical signal extracted only from the reflected component from the sea surface, 1000 processing device, 1001 storage device, 1002 input interface unit, 1011, 1012, 1013 transmission pulse.

Claims (10)

A light source unit that generates laser light in the band where the object can be reflected,
Based on the laser beam generated by the light source unit, transmitted light containing a first polarized light component and a second polarized light component different from the first polarized light component is transmitted toward the object, and the transmitted light is transmitted. Receives the reflected light reflected by the object as received light, generates a first electric signal from the first polarized light component contained in the received light, and generates a first electric signal from the second polarized light component contained in the received light. A detector that generates a second electrical signal,
A signal processing unit that calculates the speed of the object based on the difference between the first electric signal and the second electric signal.
Laser radar device equipped with. The transmitted light transmitted by the detection unit includes a transmission pulse in a first polarized state having the first polarized component and a transmission pulse in a second polarized state having the second polarized component. The laser radar device according to claim 1. The detection unit transmits a first transmitting unit that transmits a transmission pulse in a first polarized state having the first polarized component, and a second transmitting unit that transmits a transmission pulse in a second polarized state having the second polarized component. The laser radar apparatus according to claim 1 or 2, further comprising two transmitters. The laser radar apparatus according to claim 2, wherein the detection unit alternately transmits the transmission pulse in the first polarized state and the transmission pulse in the second polarized state with the passage of time. .. The laser radar apparatus according to claim 1, wherein the transmitted light transmitted by the detection unit includes a transmission pulse having both the first polarized light component and the second polarized light component. The detection unit
The laser light generated by the light source unit is polarized so as to include the first polarized light component and the second polarized light component, and the transmitted light and the reference light having the same polarization state as the transmitted light are output. Optical control unit and
A transmission / reception unit that transmits the transmitted light output from the optical control unit toward the object and receives the reflected light reflected by the object as the received light.
A wave combination unit that generates interference light by combining the received light received by the transmission / reception unit with the reference light output from the optical control unit.
It has an optical detection unit that converts the input interference light to generate an electric signal including the first electric signal and the second electric signal.
The first electric signal is the electric signal generated by converting the interference light having the first polarization component by the photodetector.
Any one of claims 1 to 5, wherein the second electric signal is the electric signal generated by converting the interference light having the second polarization component by the photodetector. The laser radar device according to the section. The signal processing unit
A low-frequency signal acquisition unit that acquires a low-frequency signal from which high-frequency components have been removed from the electrical signal generated by the photodetector unit, and a low-frequency signal acquisition unit.
The difference between the first low-frequency signal acquired by the low-frequency signal acquisition unit from the first electric signal and the second low-frequency signal acquired by the low-frequency signal acquisition unit from the second electric signal. , A difference calculation unit that calculates the difference between the first electric signal and the second electric signal,
An electric signal obtained by extracting a reflection component from the object from the first electric signal based on the difference calculated by the difference calculation unit and the first electric signal generated by the light detection unit. And the extraction part that generates
The laser radar apparatus according to claim 6, further comprising a speed calculation unit that calculates the speed of the object using an electric signal extracted by the extraction unit. The low-frequency signal acquired by the low-frequency signal acquisition unit is an envelope acquired from the electric signal generated by the light detection unit, and the first low-frequency signal is from the first electric signal. The laser radar apparatus according to claim 7, wherein the first envelope is acquired, and the second low-frequency signal is the second envelope acquired from the second electric signal. .. The speed calculation unit
A range bin dividing unit that divides the electric signal extracted by the extraction unit into a plurality of range bins, and a range bin dividing unit.
A frequency spectrum calculation unit that calculates the frequency spectrum of the electric signal divided by the range bin division unit for each range bin, and a frequency spectrum calculation unit.
A Doppler velocity calculation unit that calculates the velocity of the object from the Doppler shift amount of the frequency spectrum calculated by the frequency spectrum calculation unit, and a Doppler velocity calculation unit.
7. The laser radar apparatus according to claim 7 or 8. The optical control unit
A polarizing unit that polarizes the laser light generated by the light source unit and generates the laser light including the first polarization component and the second polarization component.
A distribution unit that distributes the laser light generated by the polarizing unit to the transmission light and the reference light, and a distribution unit.
The laser radar apparatus according to any one of claims 6 to 9, wherein the laser radar apparatus comprises.

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