Laser radar device and wind measurement method

Abstract

The frequency of the laser irradiated in the laser radar device of the disclosed technology adopts a discrete value dispersed according to the frequency difference (F). Therefore, the TOF corresponding to the distance of the target object is presented in the unit of the frequency difference (F) at every time (T), and the Doppler frequency corresponding to the speed of the target object is presented as a subtle change compared to the frequency difference (F). In this way, the disclosed technology provides a laser radar device having a structure that can distinguish the frequency information caused by the distance of the target object and the frequency information caused by the speed of the target object in a simple way.

Description

Technical Field

[0001] The disclosed technology relates to a laser radar device and a wind measurement method using the laser radar device. Background Art

[0002] Laser radar devices, also called photo radar devices or LiDAR (Light Detection and Ranging), have long been used in the fields of geology and meteorology, and have also attracted attention in recent years in the field of, for example, autonomous driving of automobiles.

[0003] The operating principle of the laser radar device is to obtain information about the distance and speed of the target by irradiating a laser and analyzing the light that hits the target. As the name suggests, the laser radar device can be considered a radar device that uses a laser. If you want to know the distance of the target, you can measure the time from the irradiation of the laser to the reflection (Time of Flight: flight time, hereinafter referred to as "TOF") and multiply the speed of the laser by TOF to find it. In addition, if you want to know the speed of the target, you can analyze the frequency of the reflected light to find the Doppler frequency, and the speed of the target can be obtained based on the relationship between the frequency of the irradiated laser and the Doppler frequency.

[0004] When the distance and speed of an object are to be determined simultaneously, TOF and Doppler frequency are determined simultaneously as described above. When these are to be determined directly, the laser radar device requires a sensor corresponding to two states, time and frequency. In response to this, a technology for converting TOF into frequency information using Frequency Modulated Continuous Wave (hereinafter referred to as "FMCW"; frequency modulated continuous wave) is disclosed. In particular, the following technology is disclosed in non-patent document 1: by combining an up-chirped FMCW and a down-chirped FMCW, the frequency difference between the irradiated light and the received light caused by the distance of the object and the frequency difference between the irradiated light and the received light caused by the speed of the object are respectively and separately determined (non-patent document 1). Figure 1 ).

[0005] Prior art literature

[0006] Non-patent literature

[0007] Non-patent document 1: D. Pierrottet et al. "Flight test performance of a high precision navigation Doppler Lidar," Proceedings of SPIE Vol. 7323, 732311 (2009) Summary of the invention

[0008] Problems to be solved by the invention

[0009] In the technology disclosed in non-patent document 1, the frequency of the irradiated light is constantly changed, and the information of up-chirp and down-chirp is used in the analysis. Non-patent document 1 discloses the technology for the purpose of navigation of a mobile body for lunar surface exploration, and there is no problem for such an object (called a hard target) located at a fixed distance.

[0010] However, in the case of wind measurement, aerosols are usually present at multiple locations in the direction of laser irradiation, and light scattered by aerosols at multiple locations is received in an overlapping manner, so the waveform of the received light becomes complicated. In the use of laser radar devices for wind measurement, a structure is required that can distinguish frequency information caused by the distance to the target object and frequency information caused by the speed of the target object in a simpler way.

[0011] The disclosed technology aims to solve the above-mentioned problems and provides a laser radar device having a structure that can distinguish frequency information caused by the distance of a target object and frequency information caused by the speed of the target object by a simple method.

[0012] Means for solving problems

[0013] The laser radar device of the disclosed technology comprises: a reference light source that oscillates laser light by continuous oscillation or quasi-continuous oscillation; a frequency modulator that applies frequency modulation to the laser light oscillated from the reference light source; a beam splitter that separates the laser light modulated by the frequency modulator into transmission light and local oscillation light; a transceiver optical system that transmits the transmission light and receives light reflected from an object; a receiver that receives the received light received by the transceiver optical system and the local oscillation light and converts each light into an electrical signal; and a receiving circuit that processes the electrical signal converted by the receiver and calculates distance information and speed information of the object, characterized in that the frequency modulation applied by the frequency modulator is a modulation that performs a step-like change of increasing or decreasing a frequency difference (F) in at least one level according to each time width (T), and the receiving circuit divides the frequency difference between the local oscillation light and the received light by the frequency difference (F), and determines the frequency difference corresponding to the remainder or the difference as the Doppler frequency.

[0014] Effects of the Invention

[0015] Since the laser radar device of the disclosed technology has the above-mentioned structure, the frequency of the irradiated laser light becomes a discrete value dispersed according to the frequency difference F. Therefore, the TOF corresponding to the distance of the target object is presented in units of the frequency difference F at every time T, and the Doppler frequency corresponding to the speed of the target object is presented as a subtle change compared to the frequency difference F. In this way, the disclosed technology provides a laser radar device having a structure that can distinguish the frequency information caused by the distance of the target object and the frequency information caused by the speed of the target object in a simple way. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural diagram showing the structure of the laser radar device according to embodiment 1.

[0017] Figure 2 This is a structural diagram showing a structural example of the receiving circuit 210 of the laser radar device according to Embodiment 1 and Embodiment 2.

[0018] Figure 3 This is a graph showing the frequency modulation applied by the phase modulator or the frequency modulator of the laser radar device of the disclosed technology.

[0019] Figure 4 Yes Figure 3 The frequency modulation shown is represented as a graph of phase modulation.

[0020] Figure 5 This is a graph showing the local oscillation light and the received light in the laser radar device of the present technology by comparing the time changes of the frequencies.

[0021] Figure 6 This is a structural diagram showing the structure of the laser radar device of embodiment 2 and embodiment 3.

[0022] Figure 7 This is a structural diagram showing a structural example of the receiving circuit 210 of the laser radar device according to the third embodiment.

[0023] Figure 8 This is a structural diagram showing the structure of a laser radar device according to embodiment 4.

[0024] Fig. 9 This is a structural diagram showing a structural example of the receiving circuit 211 of the laser radar device according to the fourth embodiment.

[0025] Fig.10 This is a graph showing frequency modulations respectively applied by the first frequency modulator 23 and the second frequency modulator 24 of the laser radar device according to the fourth embodiment.

[0026] Fig.11 This is a structural diagram showing a variation of the structure of the laser radar device of embodiment 4.

[0027] Fig.12 This is a structural diagram showing the structure of the laser radar device of embodiment 5.

[0028] Fig.13 This is a structural diagram showing a structural example of the receiving circuit 211 of the laser radar device according to the fifth embodiment. DETAILED DESCRIPTION

[0029] Embodiments of the disclosed technology will become clear from the following description with reference to the accompanying drawings.

[0030] Implementation method 1.

[0031] Figure 1 1 is a block diagram showing the structure of the laser radar device of Embodiment 1. The laser radar device of Embodiment 1 is composed of a reference light source 10, a frequency modulator 20 or a phase modulator 20B, a first beam splitter 30, an amplifier 40, a circulator 50, a transceiver optical system 60, a second beam splitter 70, a balanced detector 80, a control signal circuit 200, and a receiving circuit 210.

[0032] The reference light source 10 uses a laser source with a narrow line width. From the perspective of eye safety, a light source in the 1.5μm band is suitable. However, there is no problem even if the reference light source 10 is a light source in a band other than this. The line width of the laser is preferably narrow, but the narrower it is, the higher the price tends to be. The line width of the laser is determined by appropriate design. The reference light source 10 is preferably a continuous oscillation type, i.e., a CW (Continuous Wave) light source, but considering situations such as intermittent operation due to safety issues, it can also be a quasi-continuous oscillation type, i.e., a QCW (Quasi CW) light source.

[0033] The frequency modulator 20 or the phase modulator 20B may be any, but frequency modulation is given to the laser light emitted by the reference light source 10. For simplicity, the description of the first embodiment is based on the frequency modulator 20. In addition, the frequency modulator 20 is controlled by the control signal circuit 200. In addition, the frequency modulator 20 and the phase modulator 20B may be any, because the relationship shown by the following formula (1) holds.

[0034] dθ / dt=2πf … (1)

[0035] Here, θ represents phase, f represents frequency, π represents pi, and t represents time.

[0036] The first beam splitter 30 separates the laser modulated by the frequency modulator 20 into the transmission light and the local oscillation light. Usually, the local oscillation light does not need such a strong power, so a beam splitter with an asymmetric branching ratio such as 9:1 is often used. However, the first beam splitter 30 can also be a 5:5 beam splitter. Usually, the beam splitter used in the laser radar device sometimes uses an optical fiber, and sometimes uses other names such as an optical fiber coupler to refer to this component.

[0037] The amplifier 40 amplifies the transmission light in the laser separated by the first beam splitter 30. The amplifier 40 can be a single-stage structure or a multi-stage structure. As for the amplifier 40, an optical fiber amplifier is often used, but an optical amplifier other than an optical fiber amplifier can also be used. In the case of a multi-stage structure, an optical fiber amplifier can also be combined with an optical amplifier other than an optical fiber amplifier. In addition, in the case of a multi-stage structure, in order to remove the amplified spontaneous emission (Amplified Spontaneous Emission, hereinafter referred to as "ASE"), a filter or an isolator for preventing return light can also be inserted between the amplifiers.

[0038] The transmission light amplified by the amplifier 40 is sent to the transceiver optical system 60 via the circulator 50. Generally, a circulator refers to a device that sends light input from an optical path A to an optical path B, but light input from B is not output from A but from another optical path C. In a narrow sense, a circulator refers to a circulator using a Faraday element, and the circulator 50 may simply be a circulator that combines a polarization beam splitter and a quarter wave plate.

[0039] The transceiver optical system 60 plays the following roles: adjusting the beam diameter of the transmitted light and emitting it into the atmosphere, and collecting the received light scattered and returned from the aerosol in the atmosphere. The transceiver optical system 60 is equipped with a telescope and a beam expander. In addition, the transceiver optical system 60 can also use a scanner in order to be able to observe multiple lines of sight.

[0040] The second beam splitter 70 interferes the received light collected by the transmitting and receiving optical system 60 with the local oscillation light, and sends the two interference lights obtained by the interference to the balanced detector 80 .

[0041] The balanced detector 80 has two light receiving parts, converts the light incident on each light receiving part into an electrical signal, and outputs the difference between the two converted electrical signals. The balanced detector 80 can be an integrated light receiving element, or can be provided with a circuit that uses two photodiodes to obtain the difference of the photocurrents obtained from the two photodiodes. The balanced detector 80 functions as a receiver, and therefore, is sometimes simply referred to as a receiver.

[0042] The purpose of the second beam splitter 70 is to find the frequency difference obtained by subtracting the frequency of the received light from the frequency of the local oscillation light. That is, this structure utilizes the following property: when two lights with close frequencies interfere, a beat frequency of the frequency difference of the two lights is generated as amplitude modulation. In addition, the balanced detector 80 is used to remove the DC component. Here, regarding the frequency difference obtained by subtracting the frequency of the received light from the frequency of the local oscillation light, there is no problem even if the frequency components are respectively obtained for the local oscillation light and the received light, and then the frequency difference is obtained. In addition, the frequency of the local oscillation light at each moment is known, so it is also possible to simply find the frequency component of the received light through a time window in which the frequency of the local oscillation light is fixed, and calculate the frequency difference.

[0043] In addition, the following paragraphs will be described on the premise that the configuration includes the second beam splitter 70 and the balanced detector 80 .

[0044] The receiving circuit 210 processes the electrical signal converted by the balance detector 80 and calculates the distance information and speed information of the target object. More specifically, the receiving circuit 210 processes the differential signal output from the balance detector 80 and calculates the wind speed information for each distance. The receiving circuit 210 is composed of an electrical filter, an amplifier, an analog-to-digital converter, a computer, and the like.

[0045] Figure 2 This is a configuration example of the receiving circuit 210. The receiving circuit 210 is composed of a prefilter 300, an amplifier 310, a frequency filter 320, receivers 331 to 333, and a computer 340. The amplifier 310 may be an electric amplifier.

[0046] The differential signal output from the balanced detector 80 has unnecessary frequencies removed by the prefilter 300, and is then amplified by the amplifier 310. The amplified signal is distributed by the frequency filter 320 according to each frequency domain, and is sent to the receivers 331 to 333 according to the frequency domain. Generally, an amplifier has a frequency band characteristic, so the amplifier 310 may also have the function of the prefilter 300. In addition, in order to limit the frequency band after the frequency filter 320, the amplifier 310 may also be configured after the frequency filter 320. In this case, the prefilter 300 and the frequency filter 320 may also be common, and the number of amplifiers is required to be the same as that of the receivers. Figure 2Three receivers are depicted in the illustrated structural example, but the number is determined by appropriate design. Specifically, receivers 331 to 333 are analog-to-digital converters. Receivers 331 to 333 send received signals to computer 340. Computer 340 performs signal processing such as Fourier transform on the signals sent from receivers 331 to 333, and calculates information related to distance and wind conditions. When performing signal processing, computer 340 receives timing signals from control signal circuit 200 as needed. Computer 340 may be a general-purpose computer such as a so-called computer, or may be a dedicated integrated circuit such as ASIC (Application Specific Integrated Circuit). In addition, computer 340 may also be a combination of multiple computers.

[0047] The operation of the laser radar device and the wind measurement method of the first embodiment are performed according to Figure 3 This will become clear from the following description.

[0048] Figure 3 : is a graph showing the frequency modulation given to the transmitted light by the frequency modulator 20. That is, the frequency modulation given by the frequency modulator 20 is a modulation that performs at least one step-like change of increasing or decreasing the frequency difference F according to each time width T. As a result, the transmitted light of the laser radar device of the disclosed technology has Figure 3 The stepped frequency characteristics are shown.

[0049] The frequency difference F in this step-like change is sufficiently larger than the Doppler frequency generated by the movement of aerosols in the air. d , let the wind speed be V, let the speed of light be c, the Doppler frequency f generated by the movement of aerosols in the air d It is given by the following formula (2).

[0050] f d =-2ν0V / c … (2)

[0051] In addition, regarding distance, the farther side is defined as positive with the laser radar device as the origin. In this way, regarding speed, the side farther away from the laser radar device is also considered positive. In this way, the wind speed takes a positive value when it is a tailwind and a negative value when it is a headwind. Correspondingly, the Doppler frequency f d It can also take any positive or negative value. For example, when the frequency of light is 2[THz] (≈ wavelength 1.5[μm]), the Doppler frequency f d At wind speeds around 1 [m / s], it becomes -1.33 [MHz]. Therefore, Figure 3 As shown in the figure, if the frequency difference F is 100 [MHz], it can be said that the Doppler frequency f under normal wind conditions isd It is large enough compared to the light radar. In addition, the frequency difference F is not limited to 100 [MHz], and can be a smaller frequency or a larger frequency. For example, in meteorological terms, winds exceeding 30m / s are defined as "strong winds", but winds exceeding 30m / s rarely occur on the ground, and even if they do occur, they become storms. Therefore, it is often difficult to perform light radar measurement due to the influence of raindrops or dust. Therefore, even if the frequency difference F is set to 80 [MHz], which is equivalent to distinguishing wind speeds of about +30 [m / s] and -30 [m / s], there is no problem in practical use.

[0052] exist Figure 3 In , the properties of the transmitted light of the laser radar device in the disclosed technology are expressed from the perspective of frequency, but according to equations (1) and (2), the properties of the transmitted light can also be expressed from the perspective of phase. Figure 4 Yes Figure 3 The frequency modulation shown is a graph of phase modulation. In general, infinite phase modulation cannot be applied to a phase modulator, and in most cases, it is folded back at 2π, which is not a problem. The control signal circuit 200 controls the phase modulator 20B and gives Figure 4 The phase modulation shown is essentially the same as the frequency modulation in the disclosed technique. Figure 4 The graph is composed of broken lines, and it can be seen that the phase changes continuously. Figure 3 The phase information cannot be read at the time of switching frequency, but in frequency modulation, such as Figure 4 As shown, the phase changes continuously.

[0053] The effects of the disclosed technology will become clear from the following specific examples.

[0054] have Figure 3 The transmitted light of the laser radar device with the frequency characteristics shown is scattered by the aerosol in the atmosphere and measured as received light. The received light is affected by the Doppler shift corresponding to the speed of the aerosol as the atmospheric wind condition, and is received after the TOF corresponding to the position of the scattered aerosol, that is, the time τ.

[0055] Figure 5 This is a graph showing the comparison of the time changes of the frequencies of the local oscillation light and the received light in the laser radar device of the present disclosure technology for the specific example shown below.

[0056] For example, light scattered from aerosol located 600 [m] away from the laser radar device is received after 4 [μs], which is the time it takes for the light to travel a distance of 1200 [m]. This is because the speed of light is 300,000 kilometers per second. The local oscillation light received by the balanced detector 80 and the received light have Figure 5 In this specific example, the frequency modulator 20 applies frequency modulation in which the frequency difference F is changed stepwise by 100 [MHz] every time width T of 2 [μs].

[0057] Here, light scattered from aerosol at a position of 600 [m] is received in a time-shifted form after a TOF of 4 [μs]. Since the laser radar device of the disclosed technology uses step-like frequency modulation, the TOF information is converted into information such as a frequency difference of 200 [MHz] lower than the local oscillation light. In addition, the received light is affected by the Doppler frequency shift, so the relationship between the frequency of the received light and the frequency of the local oscillation light can be expressed by the following formula (3).

[0058] (Frequency of received light) = (Frequency of local oscillation light) - 200 [MHz] - f d … (3)

[0059] The influence of Doppler shift will be described by the following specific example. The Doppler frequency f when the frequency of light is 2 [THz] (≈ wavelength 1.5 [μm]) d At a wind speed of 1 [m / s], it is -1.33 [MHz]. Therefore, it can be seen that when the frequency of the received light is 202.66 [MHz] lower than the frequency of the local oscillation light, the wind condition at a distance of 600 [m] is +2 [m / s], that is, 2 [m / s] in the direction of the wind.

[0060] As described above, the laser radar device of the disclosed technology divides the frequency difference between the local oscillation light and the received light by the frequency difference F, and determines the frequency difference corresponding to the remainder as the Doppler frequency f d In the above specific example, the disclosed technology divides the frequency difference 202.66 [MHz] between the local oscillation light and the received light by the frequency difference F = 100 [MHz], and determines the remainder 2.66 [MHz] as the Doppler frequency f d .

[0061] In addition, when the frequency difference between the received light and the local oscillation light is 197.34 [MHz], the remainder obtained by dividing by the frequency difference F = 100 [MHz] is not considered to be 97.34 [MHz]. The reference frequency is considered to be 200 [MHz] close to 197.34 [MHz], that is, it is considered to be a difference (shortage) of 2.66 [MHz], and the wind condition at a distance of 600 [m] is -2 [m / s], that is, it is considered to be 2 [m / s] against the wind.

[0062] Figure 5An example is shown in which TOF = 4 [μs] is an exact integer multiple of the time width T = 2 [μs]. When TOF is an integer multiple of the time width T, the step-shaped frequency of the local oscillation light and the step-shaped frequency of the received light change at the same timing. That is, when the received light is observed at a fixed timing with the frequency of the local oscillation light, for example, when the received light is observed in a time window of 12 [μs] to 14 [μs] when the frequency of the local oscillation light is 400 [MHz], the frequency of the received light is a fixed value of 200 [MHz] in the entire interval.

[0063] In the disclosed technology, there is no particular problem even if TOF does not become an integer multiple of the time width T. In the following specific example, a method of considering the case where TOF does not become an integer multiple of the time width T is described.

[0064] Consider the case where TOF is 3.5 [μs]. Similarly, when the received light is observed in the time window of 12 [μs] to 14 [μs] with a local oscillation light frequency of 400 [MHz], it is 200 [MHz] at 12 [μs] to 13.5 [μs] and 300 [MHz] at 13.5 [μs] to 14 [μs]. That is, the frequency difference F is 200 [MHz] at 12 [μs] to 13.5 [μs] and 100 [MHz] at 13.5 [μs] to 14 [μs].

[0065] Let's also consider the case where TOF is 4.5 [μs]. Similarly, when the received light is observed in the time window of 12 [μs] to 14 [μs] when the frequency of the local oscillation light is 400 [MHz], it is 100 [MHz] when it is 12 [μs] to 12.5 [μs], and it is 200 [MHz] when it is 12.5 [μs] to 14 [μs]. That is, the frequency difference F is 300 [MHz] when it is 12 [μs] to 12.5 [μs], and it is 200 [MHz] when it is 12.5 [μs] to 14 [μs].

[0066] As described above, the disclosed technology can observe received light in a time window where the frequency of the local oscillation light is fixed, and obtain TOF based on information on the two frequencies of the received light observed and information on the timing of the frequency switching of the received light. Information on the frequency of the received light is obtained by Fourier transformation performed by the computer 340 .

[0067] The laser radar device may be configured to obtain the wind condition for each distance range (hereinafter referred to as a "range"). In the first embodiment, the frequency filter 320 and the receivers 331 to 333 correspond to this.

[0068] The following is a specific example of the frequency filter 320 of the first embodiment. For example, the frequency filter 320 has three types of bandpass filters. Specifically, the frequency filter 320 is a bandpass filter of 50 to 150 [MHz], 150 to 250 [MHz], and 250 to 350 [MHz]. In addition, the frequency filter 320 is configured to send the frequency component of 50 to 150 MHz to the receiver 331, send the frequency component of 150 to 250 MHz to the receiver 332, and send the frequency component of 250 to 350 MHz to the receiver 333.

[0069] When the frequency filter 320 and the receivers 331 to 333 are provided as described above, the information of the wind condition at a distance of 300 [m] can be measured by the receiver 331, the information of the wind condition at a distance of 600 [m] can be measured by the receiver 332, and the information of the wind condition at a distance of 900 [m] can be measured by the receiver 333. The computer 340 performs Fourier transformation on the electrical signals measured by each receiver, and can calculate the wind condition in each range by finding the peak frequency.

[0070] Figure 2 The structure in which the signals are separated by the frequency filter 320 in the receiving circuit 210 and then Fourier transformed is performed on each signal is shown, but the present invention is not limited thereto. The laser radar device of the disclosed technology can also use a receiver to perform AD conversion without using the frequency filter 320, and perform Fourier transformation and range decomposition after converting the digital signal.

[0071] In addition, in the signal containing the frequency component below 50 MHz corresponding to the zero distance, there is a signal generated by the light scattered by the optical system during the period from the circulator 50 to the atmosphere through the transceiver optical system 60, and received by the balanced detector 80. Such scattered light generated inside the device is usually stronger than the scattered light generated by the aerosol in the atmosphere. In order to solve this problem, the pre-filter 300 is provided to prevent the saturation of the amplifier 310, and the scattered light generated inside the device can be removed. As a result, the SN in the receiving circuit 210 can be improved.

[0072] Since the laser radar device of the first embodiment has the above-mentioned structure, it has a structure that can distinguish the frequency information caused by the distance of the target object and the frequency information caused by the speed of the target object in a simple way.

[0073] Implementation method 2.

[0074] In Embodiment 1, a structure in which the laser light is frequency modulated and then separated into the transmission light and the local oscillation light is described, but the disclosed technology is not limited to this structure. The laser radar device of Embodiment 2 performs frequency modulation or phase modulation after separating the transmission light and the local oscillation light. The same reference numerals are used for the common structural elements with Embodiment 1, and repeated descriptions are omitted.

[0075] Figure 6 1 is a structural diagram showing the structure of the laser radar device of Embodiment 2. The laser radar device of Embodiment 2 does not have a frequency modulator 20 or a phase modulator 20B in the front stage of the first beam splitter 30. Instead, the laser radar device of Embodiment 2 has a first frequency modulator 21 and a second frequency modulator 22 in parallel in the rear stage of the first beam splitter 30.

[0076] The laser light emitted from the reference light source 10 is separated into a transmission light and a local oscillation light by the first beam splitter 30. The transmission light is sent to the first frequency modulator 21, and the local oscillation light is sent to the second frequency modulator 22, and each is given frequency modulation. As also described in Embodiment 1, a phase modulator may be used instead of a frequency modulator. That is, the transmission light may be given phase modulation by the first phase modulator 21B, and the local oscillation light may be given phase modulation by the second phase modulator 22B. Both the first frequency modulator 21 and the second frequency modulator 22 are controlled by the control signal circuit 200, and modulation is performed synchronously. In the case of using the first phase modulator 21B and the second phase modulator 22B, modulation is also performed synchronously.

[0077] The advantage of using modulators for transmitting light and local oscillating light respectively becomes clear from the following specific example. In the specific example, a first phase modulator 21B and a second phase modulator 22B are used. Let the phase modulation given by the first phase modulator 21B be θ(t), and let the phase modulation given by the second phase modulator 22B be If the same phase modulation is applied to the transmission light and the local oscillation light as in Embodiment 1, θ(t) and The following formula (4) is satisfied.

[0078]

[0079] The laser radar device of the second embodiment uses the phase modulation θ(t) of the transmitted light and the phase modulation of the local oscillation light to generate a And it gives the time-shift modulation. θ(t) and The relationship satisfies the following formula (5).

[0080]

[0081] Formula (5) means that the phase modulation θ of the transmitted light and the phase modulation θ of the local oscillation light are Compared to the time delay t1.

[0082] Here, the phase modulation θ of the transmitted light is related to Figure 3 The frequency modulation shown in FIG. 1 corresponds to the phase modulation. In addition, the phase modulation θ of the transmitted light has a time delay of t1 = 1 [μs]. Thus, when the TOF is 3 [μs], the response of the received light is Figure 5 same.

[0083] As in Embodiment 1, frequency filter 320 is a bandpass filter of 50 to 150 [MHz], 150 to 250 [MHz], and 250 to 350 [MHz]. In addition, the bandpass filter is configured to send the frequency component of 50 to 150 MHz to receiver 331, the frequency component of 150 to 250 MHz to receiver 332, and the frequency component of 250 to 350 MHz to receiver 333. As a result, the information of the wind condition near the distance of 150 [m] can be measured by receiver 331, the information of the wind condition near the distance of 450 [m] can be measured by receiver 332, and the information of the wind condition near the distance of 750 [m] can be measured by receiver 333.

[0084] As described above, since the scattered light generated inside the device makes the noise large, it is difficult to observe the range including the zero distance. However, according to the laser radar device of embodiment 2, it is also possible to measure the wind condition in the range close to the zero distance. In addition to the effects described in embodiment 1, the laser radar device of embodiment 2 also has the above-mentioned effects. In addition, the positions of the first frequency modulator 21 and the second frequency modulator 24 are not limited to Figure 6 The positions of the first frequency modulator 21 and the second frequency modulator 24 may be respectively located in the relationship shown in equation (5). For example, the first frequency modulator 21 may be located between the reference light source 10 and the first beam splitter 30 .

[0085] Implementation method 3.

[0086] The configuration of the laser radar device of the third embodiment is the same as that of the second embodiment except for the receiving circuit 210. The same reference numerals are used for the same components as those of the first embodiment or the second embodiment, and duplicate descriptions are omitted.

[0087] Figure 7: is a structural diagram showing a structural example of the receiving circuit 210 of the laser radar device of embodiment 3. The laser radar device of embodiment 3 has a receiver 330, and only measures the frequency range selected by the prefilter 300. The prefilter 300 has the following functions: removing the frequency equivalent to zero distance and allowing the frequency equivalent to a certain specific range to pass. The prefilter 300 can be composed of one filter or a combination of two or more filters. In addition, the laser radar device of embodiment 3 can also use the frequency characteristics of the amplifier 310, and the amplifier can also serve as a filter.

[0088] The operation of the laser radar device according to the third embodiment will be clarified by the following specific example. The second phase modulator 22B provided in the laser radar device according to the third embodiment provides the phase modulation represented by the following equation (6):

[0089]

[0090] Compared with equation (5) of embodiment 2, equation (6) has the difference in the sign of the offset time. Equation (6) means that the phase modulation θ of the transmitted light and the phase modulation θ of the local oscillation light are Compared to the time t2 is advanced.

[0091] Here, the phase modulation θ of the transmitted light is assumed to be Figure 3 The frequency modulation shown corresponds to the phase modulation. In addition, the phase modulation θ of the transmitted light has a time advance of t2 = 2 [μs]. Thus, when the TOF is 6 [μs], the response of the received light is Figure 5 same.

[0092] The pre-filter 300 of the laser radar device of the third embodiment is a bandpass filter of 50 to 150 [MHz], and a receiver 330 is provided at the subsequent stage. In this specific example, the receiver 330 can measure a range of 600 [m]. The range to be measured can be changed by changing t2. The laser radar device of the third embodiment measures one variable range in a centralized manner.

[0093] according to Figure 5 It can be seen that when the frequency modulation is selected as up-chirp, the frequency of the local oscillation light is shifted to the side higher than the frequency of the delayed received light. On the other hand, in this specific example, the response of the received light equivalent to zero distance is located on the side where the frequency of the received light becomes 100MHz higher, corresponding to the time advance of t2=2[μs].

[0094] Usually, in the interference of light, negative frequencies and positive frequencies are measured as the same frequency with phase inversion in a processing system that uses a balanced detector to measure interference fringes and processes electrical signals. Therefore, the stronger scattered light at zero distance will be mixed into the information of the range to be measured. In order to prevent this, by applying a bias to the frequency added to the local oscillation light or the received light, the mixing of information in other ranges caused by the return of negative frequencies shown above can be prevented. That is, by adding the term of the bias frequency to the left side of equation (6) to become the following equation (7), the return of negative frequencies can be prevented.

[0095]

[0096] Among them, f o is the bias frequency. Figure 5 It is nothing more than the drawing of the local oscillation light or the movement of the drawing of the received light along the longitudinal axis.

[0097] By having the above structure, the laser radar device of embodiment 3 can measure multiple ranges by using the delay time of switching the modulation frequency of one receiver. In addition, the longer the range, the higher the frequency needs to be measured, but by configuring the laser radar device of embodiment 3 in this way, the effect of reducing the measurement frequency can also be expected. Generally, the higher the frequency, the more difficult the circuit design is, but the disclosed technology can reduce the frequency and perform the same measurement, and can expect cost reduction.

[0098] Implementation method 4.

[0099] The specific examples shown in Embodiments 1 to 3 clearly illustrate the principle of detecting wind conditions at locations of 300 [m] and multiples thereof, such as 600 [m], 900 [m], etc., when the time width T = 2 [μs] is set, where 300 [m] is half the distance that light travels in the time width T = 2 [μs]. The laser radar device of Embodiment 4 has a structure that makes it easy to find not only wind conditions at locations of dispersed distances determined by the time width T, but also wind conditions at locations between the dispersed distances.

[0100] The problem solved by the laser radar device of the fourth embodiment will become clear from the following description. In the following description, the time width T is assumed to be the same as the specific example shown in the above embodiment, which is 2 [μs]. Figure 3As shown, the frequency modulation is an up-chirped signal with a frequency difference of F = 100 [MHz]. For example, light scattered from an aerosol at a distance of 450 [m] is received 3 [μs] after being irradiated from the device. Here, the period during which the frequency of the local oscillation light is fixed is used as an observation window, and information related to the frequency of the received light is observed. For example, consider the observation window when the frequency of the local oscillation light is fixed at 300 [MHz] from 4 [μs] to 6 [μs]. During the first half of the observation window, the frequency of the received light is approximately 100 [MHz], with the Doppler frequency added. During the second half of the observation window, the frequency of the received light is 200 [MHz], with the Doppler frequency added. That is, there is a mixture of time when the frequency of the received light is approximately 200 [MHz] lower than the frequency of the local oscillation light and time when it is approximately 100 [MHz] lower. In this way, when a signal whose frequency is switched midway is Fourier transformed through a wide time window of more than one cycle, a peak is generated at the intermediate frequency. Therefore, it is difficult to distinguish the position information and the speed information of the above-mentioned observation object only by the structures shown in Embodiments 1 to 3.

[0101] The laser radar device of the fourth embodiment has as its subject the systematic determination of wind conditions at a point close to the boundary between ranges.

[0102] In order to solve the above-mentioned problem, the laser radar device of embodiment 4 has two discretely modulated optical radar systems, and has a structure for respectively imparting opposite frequency modulation to the two systems. In addition, the lasers of the two systems are respectively irradiated into the atmosphere, and the received light reflected by the aerosol is mixed in the receiving circuit of the laser radar device.

[0103] Figure 8 : is a structural diagram showing the structure of the laser radar device of embodiment 4. Figure 8 As shown, the laser radar device of embodiment 4 includes a first reference light source 11, a second reference light source 12, a first frequency modulator 23, a second frequency modulator 24, a first beam splitter 31, a second beam splitter 32, an amplifier 40, a circulator 50, a transceiver optical system 60, a third beam splitter 71, a fourth beam splitter 72, a first balanced detector 81, a second balanced detector 82, a channel combiner 91, a channel splitter 92, a control signal circuit 201, and a receiving circuit 211.

[0104] In the description of the technology of the fourth embodiment, the same reference numerals are used as much as possible for the same components as those of the above-mentioned embodiments, and duplicate descriptions are omitted as appropriate.

[0105] The first reference light source 11 is the same as the reference light source 10 in the laser radar device of Embodiments 1 to 3. The second reference light source 12 is a reference light source having a wavelength different from that of the first reference light source 11. The wavelength of the second reference light source 12 is different from that of the first reference light source 11 to facilitate coupling and separation of each laser. Instead of making the wavelength different from that of the first reference light source 11, the second reference light source 12 may be made to have a different polarization to make the mode different.

[0106] The first frequency modulator 23 and the second frequency modulator 24 function in the same manner as the frequency modulator 20 of the laser radar apparatus of embodiments 1 to 3. The first frequency modulator 23 and the second frequency modulator 24 can be replaced by the first phase modulator 23B and the second phase modulator 24B, respectively. The simultaneity of the modulation added by the first frequency modulator 23 and the second frequency modulator 24 is important. Therefore, the laser radar apparatus of embodiment 4 includes a control signal circuit 201, and the first frequency modulator 23 and the second frequency modulator 24 are controlled by the control signal circuit 201.

[0107] The first beam splitter 31 and the second beam splitter 32 function in the same manner as the first beam splitter 30 of the laser radar device of Embodiments 1 to 3. The lasers output from the first reference light source 11 and the second reference light source 12 are modulated by the first frequency modulator 23 and the second frequency modulator 24, respectively, and are separated into transmission light and local oscillation light by the first beam splitter 31 and the second beam splitter 32, respectively. The branching ratios of the first beam splitter 31 and the second beam splitter 32 are determined by design.

[0108] The transmission light separated by the first beam splitter 31 and the transmission light separated by the second beam splitter 32 are combined by a channel combiner 91. In the case where the second reference light source 12 emits a laser with a wavelength different from that of the first reference light source 11, the channel combiner 91 can be formed by a wavelength filter that transmits the wavelength of the first reference light source 11 and reflects the wavelength of the second reference light source 12. Generally, a wavelength filter composed of an optical fiber is sometimes referred to as a WDM coupler. In the case where the polarization light of the second reference light source 12 is different from that of the first reference light source 11, the channel combiner 91 can also be a polarization beam splitter. In addition, a polarization beam splitter is sometimes referred to as a polarization coupler or a polarization combiner.

[0109] The transmission light combined by the channel combiner 91 is amplified by the amplifier 40. The amplifier 40 is the same as the amplifier of the laser radar device in the first to third embodiments. Figure 8In the structural example shown, two channels are combined in the front stage of the amplifier 40, and the optical path is made common after the amplifier 40, thereby simplifying the structure. The laser radar device of the disclosed technology is not limited to this, and two channels can be prepared and an amplifier 40 can be provided for each channel. The upper limit of the output of the amplifier 40 is limited by the nonlinear effect, so the amplifier with the number of channels can amplify the light intensity of each channel with high intensity. In the case where the amplifier 40 has a multi-stage structure, a channel combiner 91 can also be configured between the first-stage amplifier 40 and the second-stage amplifier 40.

[0110] The output from the amplifier 40 is sent to the transceiver optical system 60 through the circulator 50. This operation is the same as that of the laser radar apparatus of Embodiments 1 to 3. It should be noted that when lasers of different wavelengths are used in the first reference light source 11 and the second reference light source 12, the transceiver optical system 60 is an optical system with reduced chromatic aberration.

[0111] The laser beam irradiated into the atmosphere is reflected by the aerosol in the atmosphere and enters the transceiver optical system 60 as received light. The received light after the incident is separated from the transmitted light by the circulator 50 and enters the channel splitter 92. The channel splitter 92 is a structural element that plays a role opposite to that of the channel combiner 91. That is, the channel splitter 92 emits the component of the received light corresponding to the wavelength of the first reference light source 11 to the third beam splitter 71, and emits the component of the received light corresponding to the wavelength of the second reference light source 12 to the fourth beam splitter 72. In addition, there is no problem even if the wavelength of the second reference light source 12 interferes with the third beam splitter 71 and the wavelength of the first reference light source 11 interferes with the fourth beam splitter 72. The channel splitter 92 can also be composed of a beam splitter. However, when it is composed of a beam splitter, the light intensity is lost by 3 [db].

[0112] The component corresponding to the wavelength of the first reference light source 11 emitted from the channel splitter 92 and the local oscillation light separated by the first beam splitter 31 interfere in the third beam splitter 71. The two interference lights obtained by the third beam splitter 71 are emitted to the first balanced detector 81. In addition, the system from the second reference light source 12 is also the same, so the description is omitted here.

[0113] The receiving circuit 211 processes the signals obtained from the first balance detector 81 and the second balance detector 82 to calculate the wind speed information for each distance. The receiving circuit 211 includes an electric filter, an amplifier, an analog-to-digital converter, and a computer. Fig. 9 2 is a block diagram showing the structure of the receiving circuit 211. Fig. 9As shown, the receiving circuit 211 includes a first prefilter 301, a second prefilter 302, a first amplifier 311, a second amplifier 312, a first frequency filter 321, a second frequency filter 322, a first mixer 351, a second mixer 352, a third mixer 353, a receiver 330 (331, 332, 333), and a computer 340.

[0114] The processing flow of the receiving circuit 211 of the laser radar device of the fourth embodiment is the same as that of the first embodiment up to the first prefilter 301, the first amplifier 311, and the first frequency filter 321. In addition, the receiving circuit 211 also processes the signal from the second balanced detector 82, and therefore has the second prefilter 302, the second amplifier 312, and the second frequency filter 322 in parallel. The first frequency filter 321 distributes the signal output from the first amplifier 311 to the first mixer 351, the second mixer 352, and the third mixer 353 according to each frequency and outputs it. Fig. 9 Although the configuration includes three mixers, the present invention is not limited thereto and any number of mixers may be provided. Similarly, the second frequency filter 322 distributes the signal output from the second amplifier 312 to the first mixer 351 , the second mixer 352 , and the third mixer 353 for each frequency and outputs the signal.

[0115] The first mixer 351, the second mixer 352, and the third mixer 353 multiply the received signals to output the sum frequency or difference frequency signals to the receiver 330 (331, 332, 333). Usually, the phase of the two input signals determines whether the sum frequency signal or the difference frequency signal is obtained by the mixer. Therefore, the first mixer 351, the second mixer 352, and the third mixer 353 may also have a phase adjustment mechanism. The processing flow from the receiver 330 (331, 332, 333) to the computer 340 is the same as that of the first embodiment.

[0116] The operating principle of the laser radar device of embodiment 4 becomes clear through the specific example described in accordance with the following figures. Fig.10 It is a graph showing the frequency modulation respectively given by the first frequency modulator 23 and the second frequency modulator 24 of the laser radar device of embodiment 4. In addition, as described in the description of the above embodiment, the first frequency modulator 23 and the second frequency modulator 24 can be replaced by the first phase modulator 23B and the second phase modulator 24B, respectively.

[0117] The frequency modulations applied by the first frequency modulator 23 and the second frequency modulator 24 are modulations that perform at least one step-like change of increasing or decreasing the frequency difference F for each time width T. The transmission light of the laser radar device of the fourth embodiment has Fig.10The illustrated step-shaped frequency characteristics. Fig.10 The example shows a 5-step frequency modulation with a time width T = 2 [μs] and a frequency difference F = 100 [MHz]. The first frequency modulator 23 adopts an up-chirp step frequency modulation, and the second frequency modulator 24 adopts a down-chirp step frequency modulation. In the disclosed technology, the frequency difference F is a value sufficiently large compared to the Doppler shift frequency.

[0118] The laser radar device of the fourth embodiment is characterized in that two systems of transmission light are generated, one of which is set to be up-chirped and the other is set to be down-chirped. The transmission light of the two systems is emitted into the atmosphere respectively, scattered by the aerosol in the atmosphere, and measured as received light. The received light interferes with the local oscillation light and is received by the balanced detector.

[0119] The effect of the laser radar device of embodiment 4 becomes clear through the following specific example. The specific example considers the case where aerosol exists at a distance of 600 [m]. In this specific example, the received light is delayed by 4 [μs] compared with the local oscillation light. The received light corresponding to the chirped step-shaped local oscillation light has a frequency of -200 [MHz] + Doppler frequency f compared with the frequency of the local oscillation light. d On the contrary, the received light corresponding to the down-chirped step-shaped local oscillation light has a frequency of +200 [MHz] + Doppler frequency f compared to the frequency of the local oscillation light. d frequency.

[0120] The laser radar device of the fourth embodiment includes a first frequency filter 321 and a second frequency filter 322, so that two systems of processing can be performed. The first frequency filter 321 and the second frequency filter 322 output frequency components of 50 [MHz] to 150 [MHz] to the first mixer 351, output frequency components of 150 [MHz] to 250 [MHz] to the second mixer 352, and output frequency components of 250 [MHz] to 350 [MHz] to the third mixer 353. As a result, in the laser radar device of the fourth embodiment, it is intended that the receiver 331 measures information on wind conditions at a distance of 300 [m], the receiver 332 measures information on wind conditions at a distance of 600 [m], and the receiver 333 measures information on wind conditions at a distance of 900 [m].

[0121] The purpose of the mixer 350 (351, 352, 353) is to obtain a sum frequency by multiplying the two input signals. In the specific example of an aerosol at a distance of 600 [m], "-200 [MHz] + Doppler frequency f d "Signal and "200[MHz]+Doppler frequency f dThe signal " is input to the second mixer 352. The second mixer 352 converts the signal having the Doppler frequency f d The signal of the sum frequency with twice the frequency is output to the receiver 333.

[0122] Next, let us consider a specific example of an aerosol at a distance of 450 [m], which is the subject of the laser radar device of Embodiment 4. The received light of the up-chirped system is observed as "-200 [MHz] + Doppler frequency f d ", in the second half of the observation window it is observed as "-100[MHz]+Doppler frequency f d The corresponding down-chirped system received light is observed as “+200[MHz]+ Doppler frequency f” in the first half of the observation window. d ", in the second half of the observation window it is observed as "+100[MHz]+Doppler frequency f d In this specific example, mixer 350 (351, 352, 353) also outputs a signal having a Doppler frequency f d A signal with a frequency that is twice the sum frequency of the signal.

[0123] Fig.11 1 is a structural diagram showing a variation of the structure of the laser radar device according to the fourth embodiment. Fig.11 As shown, a local oscillation light frequency modulator 25 may be inserted into any of the two systems. The following specific example makes the effect of inserting the local oscillation light frequency modulator 25 clear. For example, the local oscillation light frequency modulator 25 reduces the frequency of the first local oscillation light by 100 [MHz]. Light scattered from an aerosol at a distance of 450 [m] is received 3 [μs] after being irradiated from the device. The received signal of the first system becomes "-300 [MHz] + Doppler frequency f in the first half of the observation window. d ", in the second half of the observation window it becomes "-200MHz+f d On the other hand, the received signal of the second system becomes "+200[MHz]+Doppler frequency f" in the first half of the observation window. d ", in the second half of the observation window it becomes "+100MHz+f d frequency".

[0124] In this case, the mixer 350 (351, 352, 353) outputs -100 MHz plus twice the Doppler frequency f d In this way, Fig.11The structure of the modified example shown can prevent the Doppler signal from coming near the DC component with large noise, and it can be expected that the SN will be improved. Here, the local oscillation light frequency modulator 25 can also be replaced by the local oscillation light phase modulator 25B. In addition, the local oscillation light frequency modulator 25 can also be a structure that uses an acousto-optic modulator (Acousto-Optic Modulator: AOM) as a frequency shifter. In addition, the local oscillation light frequency modulator 25 can be inserted into the second local oscillation light side, or can be inserted between the first beam splitter 31 and the channel combiner 91 to shift the frequency of the first signal light. Alternatively, the local oscillation light frequency modulator 25 can also be a structure that shifts the frequency of the second signal light.

[0125] In other words, the laser radar device of embodiment 4 comprises: a first balanced detector 81, which receives the received light and the first local oscillation light and converts each light into a first electric signal; a second balanced detector 82, which receives the received light and the second local oscillation light and converts each light into a second electric signal; and a receiving circuit, which processes the first electric signal and the second electric signal converted by the first balanced detector 81 and the second balanced detector 82 to calculate the distance information and speed information of the target object, characterized in that the frequency modulation assigned by the first frequency modulator 23 is a modulation that performs a step-like change of increasing or decreasing the frequency difference F according to each time width T for at least one level, and the frequency modulation assigned by the second frequency modulator 24 is a modulation opposite to the first frequency modulator 23 that reduces or increases the frequency difference F according to each time width T, and the Doppler frequency f is obtained by mixing the frequencies of the received light for the first transmitted light and the received light for the second transmitted light. d .

[0126] By having the above structure, the laser radar device of embodiment 4 not only has the effects of the laser radar device of the above-mentioned embodiment, but also can measure the wind conditions at any position with high accuracy regardless of the range acquisition method.

[0127] Implementation method 5.

[0128] The laser radar device of the fifth embodiment is obtained by adding a new structure to the structure of the laser radar device of the fourth embodiment. The laser radar device of the fifth embodiment uses the first reference light source 11 by matching the first reference light source 11 with the absorption line of the gas. Here, the gas refers to the gas in the atmosphere, the exhaust gas of the factory, or the gas leaked from the piping. The description of the technology of the fifth embodiment uses the same reference numerals as much as possible for the structural elements common to the above-mentioned embodiments, and the repeated description is appropriately omitted.

[0129] Fig.12 : is a structural diagram showing the structure of the laser radar device of embodiment 5. Fig.12 As shown, the laser radar device of embodiment 5 includes a control device 220 for controlling the first reference light source 11. The control device 220 locks the first reference light source 11 to the absorption line of the gas. The laser radar device of embodiment 5 can measure the concentration distribution of the gas in the atmosphere by setting the wavelength of the second reference light source 12 to a wavelength with less absorption by the above-mentioned gas. In the case where the first reference light source 11 is a laser diode, the wavelength can be fine-tuned using temperature or current value. Usually, the absorption line of the gas is narrow, so the control performed by the control device 220 considers feedback control using the gas chamber. In the case where the absorption line of the gas is relatively thick, the control device 220 can control the temperature or current value of the first reference light source 11 through an open loop to lock the wavelength of the first reference light source 11 to the absorption line of the gas.

[0130] Fig.13 2 is a structural diagram showing a structural example of the receiving circuit 211 of the laser radar device according to the fifth embodiment. Fig.13 As shown in FIG. 1 , the receiving circuit 211 includes a first frequency filter 321 and a second frequency filter 322. The signals distributed by the first frequency filter 321 and the second frequency filter 322 for each frequency are divided into two systems by the first signal separator 361 and the second signal separator 362, respectively. Fig.13 Only the first signal separator 361 and the second signal separator 362 are shown, but the number of signal separators 360 required for the distance range needs to be set. The signals separated by the signal separator 360 (361, 362) are measured by the first gas concentration measurement receiver 371 and the second gas concentration measurement receiver 372, respectively. The signal intensity measured by the first gas concentration measurement receiver 371 is weaker than the signal intensity measured by the second gas concentration measurement receiver 372 due to gas absorption. The laser radar device of embodiment 5 measures the concentration distribution of the gas based on the signal intensity ratio.

[0131] In the laser radar device of embodiment 5, in other words, the first reference light source 11 radiates a first laser whose wavelength is controlled to match the absorption line of the gas component to be measured, and the second reference light source 12 radiates a second laser of a wavelength different from that of the first reference light source 11. It also has a first gas concentration measurement receiver 371 for receiving the component in the received light corresponding to the first laser, and a second gas concentration measurement receiver 372 for receiving the component in the received light corresponding to the second laser, and can decompose and measure the concentration of the gas components in the atmosphere according to each distance.

[0132] The laser radar device of embodiment 5 can measure wind conditions by combining with the method shown in embodiment 4. Regarding the measurement of wind conditions, the signal separated by the first signal separator 361 and the second signal separator 362 is input to the first mixer 351. The first mixer 351 can output the sum frequency to the receiver 331 and calculate the Doppler frequency f d .

[0133] Since the laser radar device of embodiment 5 has the above-mentioned structure, it is possible to simultaneously measure the distribution of gas in the atmosphere and the wind conditions.

[0134] Industrial Applicability

[0135] The laser radar device of the disclosed technology can be used as a device for measuring wind conditions and gas distribution in the atmosphere.

[0136] Description of Reference Numerals

[0137] Reference light source 10, first reference light source 11, second reference light source 12, frequency modulator 20, phase modulator 20B, first frequency modulator 21, 23, first phase modulator 21B, 23B, second frequency modulator 22, 24, second phase modulator 22B, 24B, local oscillation light frequency modulator 25, local oscillation light phase modulator 25B, first beam splitter 30, 31, second beam splitter 32, amplifier 40, circulator 50, transceiver optical system 60, second beam splitter 70, third beam splitter 71, fourth beam splitter 72, balanced detector 80, first balanced detector 81, second balanced detector 82, channel combiner 91, channel splitter 92, control signal Circuits 200, 201, receiving circuits 210, 211, control device 220, prefilter 300, first prefilter 301, second prefilter 302, amplifier 310, first amplifier 311, second amplifier 312, frequency filter 320, first frequency filter 321, second frequency filter 322, receivers 330, 331, 332, 333, computer 340, mixer 350, first mixer 351, second mixer 352, third mixer 353, signal separator 360, first signal separator 361, second signal separator 362, first gas concentration measuring receiver 371, second gas concentration measuring receiver 372.

Claims

1. A laser radar device, comprising: a reference light source that oscillates laser light in a continuous oscillation mode or a quasi-continuous oscillation mode; a frequency modulator that applies frequency modulation to the laser light oscillated from the reference light source; A beam splitter that separates the laser light modulated by the frequency modulator into a transmission light and a local oscillation light; a transceiver optical system for transmitting the transmission light and receiving the light reflected from the target object; a receiver that receives the received light received by the transceiver optical system and the local oscillation light and converts each light into an electrical signal; as well as a receiving circuit, which processes the electrical signal converted by the receiver and calculates the distance information and speed information of the target object, It is characterized in that The frequency modulation imparted by the frequency modulator is a modulation that performs at least one step-like change of increasing or decreasing the frequency difference (F) for each time width (T), The receiving circuit divides the frequency difference between the local oscillation light and the received light by the frequency difference (F), and determines the frequency difference corresponding to the remainder or the difference as the Doppler frequency (f d ), wherein the time of flight (TOF) corresponding to the distance to the target object is presented in units of the frequency difference (F) every the time width (T), and the Doppler frequency corresponding to the speed of the target object is presented as a slight change compared to the frequency difference (F).

2. The laser radar device according to claim 1, characterized in that: The frequency difference (F) is greater than twice the Doppler frequency corresponding to a wind speed of 30 [m / s].

3. The laser radar device according to claim 1, characterized in that: It is possible to impart modulation in which time shift is performed to the transmission light and the local oscillation light.

4. The laser radar device according to claim 1, characterized in that: A bias can be applied to the frequency added to the local oscillation light or the received light.

5. A laser radar device comprising: A first reference light source that oscillates laser light by continuous oscillation or quasi-continuous oscillation; a second reference light source that oscillates laser light by continuous oscillation or quasi-continuous oscillation; a first frequency modulator for applying frequency modulation to the laser light oscillated from the first reference light source; a second frequency modulator for applying frequency modulation to the laser light oscillated from the second reference light source; a first beam splitter for separating the laser light modulated by the first frequency modulator into a first transmission light and a first local oscillation light; a second beam splitter for separating the laser light modulated by the second frequency modulator into a second transmission light and a second local oscillation light; an amplifier that amplifies the first transmitted light and the second transmitted light; a transceiver optical system that transmits the amplified first transmission light and the second transmission light, and receives light reflected from the target object as received light; a first balanced detector that receives the received light and the first local oscillation light and converts each light into a first electrical signal; a second balanced detector that receives the received light and the second local oscillation light and converts each light into a second electric signal; and a receiving circuit that processes the first electrical signal and the second electrical signal converted by the first balanced detector and the second balanced detector to calculate distance information and speed information of the target object, It is characterized in that The frequency modulation provided by the first frequency modulator is a modulation that performs at least one step-like change of increasing or decreasing the frequency difference (F) according to each time width (T), The frequency modulation provided by the second frequency modulator is a modulation opposite to that of the first frequency modulator, which reduces or increases the frequency difference (F) according to each time width (T). The Doppler frequency (f d ), wherein the time of flight (TOF) corresponding to the distance to the target object is presented in units of the frequency difference (F) every the time width (T), and the Doppler frequency corresponding to the speed of the target object is presented as a slight change compared to the frequency difference (F).

6. The laser radar device according to claim 5, characterized in that: The first reference light source radiates a first laser beam, the wavelength of which is controlled to match an absorption line of a gas component to be measured. The second reference light source radiates a second laser beam, the wavelength of which is different from that of the first reference light source. The laser radar device also includes: a first gas concentration measurement receiver that receives a component corresponding to the first laser light in the received light; and The second gas concentration measurement receiver receives a component corresponding to the second laser light in the received light, and decomposes and measures the concentration of the gas component for each distance.

7. A wind measurement method, wherein: By oscillating the laser in a continuous oscillation mode or a quasi-continuous oscillation mode, frequency modulation is imparted to the laser, The modulated laser light is separated into the transmission light and the local oscillation light. amplifying the transmitted light, sending the amplified transmission light, receiving the light reflected from the target object as the reception light, further receiving the received light and the local oscillation light, converting each light into an electrical signal, The converted electrical signal is processed to calculate the distance information and speed information of the target object. It is characterized in that Frequency modulation is performed as follows: at least one level of step-like change is performed to increase or decrease the frequency difference (F) according to each time width (T), The frequency difference between the local oscillation light and the received light is divided by the frequency difference (F), and the frequency difference corresponding to the remainder or the difference is determined as the Doppler frequency (f d ), wherein the time of flight (TOF) corresponding to the distance to the target object is presented in units of the frequency difference (F) every the time width (T), and the Doppler frequency corresponding to the speed of the target object is presented as a slight change compared to the frequency difference (F).

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