JP6822667B2 - Doppler lidar device and eddy warning system - Google Patents

Description

The present invention relates to a Doppler lidar device and an eddy warning system using the Doppler lidar device.

In recent years, a Doppler lidar device using a laser beam has been proposed as a device for detecting an air flow. This Doppler lidar device has been proposed as a ground facility, but a multi-rider system to be mounted on an aircraft has also been proposed (see Patent Document 1).

The multi-rider system of Patent Document 1 enables measurement in a wider range than the conventional rider system, and further, measures the airflow information for reducing the sway of the airframe used at the time of intrusion of turbulence in a short cycle to cause an aircraft eddy accident. It is intended to be used for prevention.

Here, when the irradiation direction of the laser beam is mechanically changed to measure the airflow information in various directions, there is a mechanical limit in the measurement cycle. There is also a problem that the weight is increased by the drive mechanism.

On the other hand, the multi-rider system of Patent Document 1 is equipped with two or more sets of Doppler lidar type optical remote airflow measuring devices using laser light in a relative position fixed relationship, and lasers of the same wavelength are provided from each device. It has a function to radiate and receive scattered light at each device. It is said that this makes it possible to expand the measurement area or shorten the measurement cycle.

However, the above-mentioned multi-rider system is simply equipped with two or more sets of optical remote airflow measuring devices to expand the measuring area. Therefore, there remains a problem that the number of required optical remote airflow measuring devices increases according to the required measurement area.

Japanese Unexamined Patent Publication No. 2012-83267

In view of the above problems, it is an object of the present invention to provide a Doppler lidar device capable of high-speed scanning and an eddy warning system.

In the present invention, a laser light source that generates laser light, a radiation unit that radiates the laser light emitted by the laser light source into the atmosphere, and the emitted laser light are scattered by measurement target particles suspended in the atmosphere. A Doppler lidar device that includes a light receiving unit that receives the scattered light and measures the moving speed of the particles to be measured based on the Doppler shift of the scattered light, and the laser light that is incident on the subsequent stage of the radiation unit. It is a Doppler lidar device provided with an optical phase changing means for changing the traveling direction of light by changing the phase of the light.

INDUSTRIAL APPLICABILITY According to the present invention, a Doppler lidar device capable of high-speed scanning and an eddy warning system can be provided.

The block diagram which shows the structure of the Doppler lidar apparatus. Explanatory drawing explaining the structure of the reflection type optical phase modulator. Explanatory drawing explaining the mechanism of optical phase modulation. Explanatory drawing explaining an example of optical phase modulation control. Explanatory drawing of an aircraft equipped with a Doppler lidar device. Screen configuration diagram of the display.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram showing the configuration of the Doppler lidar device 1.

The transmitting unit 3 that radiates (transmits) the laser light into the atmosphere, the receiving unit 4 that receives (receives) the scattered light scattered by the measurement target particles in which the emitted laser light floats in the atmosphere, and the scattered light. In the signal processing unit 5 that measures the moving speed (wind speed of the airflow) of the particles to be measured based on the Doppler shift, the display 6 that displays the measurement result of the wind speed, and the rear stage of the transmission unit 3 and the front stage of the reception unit 4. It is provided with an optical head portion 7 provided.

<Transmitter>
The transmission unit 3 includes a laser light source 2 that generates laser light. The laser light source 2 can be composed of, for example, a semiconductor laser that continuously generates near-infrared laser light having a wavelength of 1.5 μm. The output of the laser light is controlled by the laser light output control unit 21 connected to the laser light source 2.

The laser light generated by the laser light source 2 is output to the transmission unit 3 through the small-diameter optical fiber 30. Here, as the small-diameter optical fiber 30, an optical fiber having a small core diameter, for example, a core diameter of 10 μm is used.

The transmission unit 3 is provided with an optical isolator 31, an optical branch coupler 33, a pulse generator 35, an optical isolator 36, an AMP 38, and a circulator 39 in the subsequent stage of the laser light source 2, and is connected in series in this order by an optical fiber. There is. The optical fiber used is the above-mentioned small-diameter optical fiber except for connecting the AMP 38 and the circulator 39. On the other hand, as the optical fiber connecting the AMP 38 and the circulator 39, a large-diameter optical fiber having a large core diameter, for example, a core diameter of 30 μm is used.

The laser light emitted from the laser light source 2 is first input to the optical isolator 31.
The optical isolator 31 removes the light reflected and returned from the traveling direction side of the laser beam.

The optical isolator 31 is connected to the optical branch coupler 33 by a small-diameter optical fiber 30a. The small-diameter optical fiber 30a is provided with an optical branch coupler 32a and a photosynthetic coupler 32b on the optical isolator 31 side and the optical branch coupler 33 side, respectively.

The optical branch coupler 32a includes an optical branch output terminal and is connected to an optical input terminal of a monitor (not shown). Further, the photosynthesis coupler 32b includes a photosynthesis input terminal and is connected to an optical output terminal of a monitor (not shown).

The optical branch coupler 32a branches the laser light that has passed through the optical isolator 31, and here, 1% is output from the optical branch output terminal to the monitor, and the remaining 99% is output to the photosynthetic coupler 32b through the optical fiber 30a.

The branched laser light output to the monitor is input to the photosynthesis coupler 32b from the photosynthesis input terminal after passing through the monitor. Then, in the photosynthetic coupler 32b, the branched laser light that has passed through the monitor and input and the remaining laser light that has passed through the small-diameter optical fiber 30a merge. The laser light after merging is output to the optical branch coupler 33 through the small-diameter optical fiber 30a.

The monitor indirectly monitors the state of the laser beam passing through the small-diameter optical fiber 30a by monitoring the branched laser beam passing through the monitor. As described above, the optical branch coupler 32a and the photosynthetic coupler 32b function as an output port and an input port for the branch laser light for the monitor.

The optical branch coupler 33 branches the input laser light. Here, 1% is output to the photosynthetic coupler 44 of the receiving unit 4 through the small-diameter optical fiber 30c with 1% as reference light, and the remaining 99% is output to the pulse generator 35 through the small-diameter optical fiber 30b.

The pulse generator 35 uses, for example, an acousto-optic modulator (AOM) to generate a short pulse of laser light. The pulse width and time interval of the generated short pulse are controlled by the AOM driver 34 connected to the pulse generator 35.

The pulse generator 35 and the AMP 38 are connected by a small-diameter optical fiber 30d, and the small-diameter optical fiber 30d includes an optical isolator 36, an optical branch coupler 37a that functions as an output port and an input port for branch laser light for monitoring, and an optical branch coupler 37a. The photosynthetic coupler 37b is provided in this order.

The pulsed laser light generated by the pulse generator 35 passes through the optical isolator 36, the optical branch coupler 37a, and the photosynthetic coupler 37b via the small-diameter optical fiber 30d, and is output to the AMP 38.

The optical isolator 36 removes the light reflected and returned from the traveling direction side of the pulsed laser light. Further, the optical branch output terminal of the optical branch coupler 37a and the photosynthetic input terminal of the photosynthetic coupler 37b are connected to the optical input terminal and the optical output terminal of the monitor (not shown), respectively, and the monitor passes through the branch. By monitoring the laser beam, the state of the pulsed laser beam passing through the small-diameter optical fiber 30d is indirectly monitored.

The AMP 38 is, for example, an amplifier such as an erbium-doped fiber amplifier (EDFA), which amplifies pulsed laser light. The output control of the pulsed laser light is performed by the laser light output control unit 21 connected to the AMP 38.

The amplified pulsed laser light is output from the AMP 38 to the port P1 of the optical circulator 39 that separates the transmitted / received light through the large-diameter optical fiber 40.

The optical head portion 7 is connected to the port P2 of the optical circulator 39 via the large-diameter optical fiber 40a, and is also received via the large-diameter optical fiber 40b to the port P3 of the optical circulator 39. The unit 3 is connected.

The pulsed laser light (transmitted light) input from the port P1 to the optical circulator 39 is output from the port P2. Then, it is output to the optical head portion 7 through the large-diameter optical fiber 40a. After that, the pulsed laser light (transmitted light) is scanned by the optical head unit 7 and radiated into the atmosphere.

Further, a signal processing unit 5 is connected to the transmission unit 3 configured in this way. By the control of the signal processing unit 5, the irradiation timing of the laser beam transmitted from the transmitting unit 3 is controlled.

<Receiver>
The receiving unit 4 includes an optical conversion adapter 41, a photosynthetic coupler 44, and a photodetector 45. The optical conversion adapter 41 and the photosynthetic coupler 44 are connected by a small-diameter optical fiber 30e, and the photosynthetic coupler 44 and the photodetector 45 are connected to each other. Are connected by a small-diameter optical fiber 30f.

The optical conversion adapter 41 is connected to the port P3 of the optical circulator 39 via the large-diameter optical fiber 40b.

The pulsed laser light radiated from the optical head unit 7 into the atmosphere is scattered by the measurement target particles floating in the atmosphere and becomes scattered light. Then, after radiating the pulsed laser light, a part of the scattered light is incident on the optical head portion 7 which is on standby in that position. The scattered light incident on the optical head portion 7 is input as received light to the port P2 of the circulator 39 through the large-diameter optical fiber 40a. Then, the received light input to the port P2 is output from the port P3 and output to the optical conversion adapter 41 through the large-diameter optical fiber 40b.

The optical conversion adapter 41 is an adapter for connecting optical fibers having different core diameters, and here, the received light input through the large diameter optical fiber 40b is output to the small diameter optical fiber 30e having a small core diameter.

The small-diameter optical fiber 30e is provided with an optical isolator 42, an optical branch coupler 43a that functions as an output port and an input port for branch laser light for monitoring, and a photosynthetic coupler 43b in this order.

The received light optically converted by the optical conversion adapter 41 passes through the optical isolator 42, the optical branch coupler 43a, and the photosynthetic coupler 43b via the small-diameter optical fiber 30e, and is output to the photosynthetic coupler 44.

The optical isolator 42 removes the light reflected from the traveling direction side of the received light and returned. Further, the optical branch output terminal of the optical branch coupler 43a and the photosynthetic input terminal of the photosynthetic coupler 43b are connected to the optical input terminal and the optical output terminal of the monitor (not shown), respectively, and the monitor passes through the branch. By monitoring the laser beam, the state of the received light passing through the small-diameter optical fiber 30e is indirectly monitored.

The photosynthetic coupler 44 synthesizes the reference light input from the optical branch coupler 33 of the transmission unit 3 and the received light, and outputs the synthesized light to the photodetector 45 through the small-diameter optical fiber 30f.

The wavelength of the received light changes based on the Doppler effect according to the moving speed of the particles to be measured suspended in the atmosphere. Therefore, the photodetector 45 detects the beat signal from the combined light in which the reference light and the received light are combined by the optical heterodyne detection.

<Signal processing unit>
The signal processing unit 5 determines the intensity of the beat signal from the beat signal detected by the light detector 45, the round-trip delay time from transmitting the pulsed laser light (transmitted light) to receiving the scattered light (received light). And the Doppler frequency shift are extracted, and the amount (concentration) of the measurement target particle, the distance to the measurement target particle, and the moving speed of the measurement target particle are calculated, respectively. These calculations are performed for each radiation direction (line-of-sight direction) of the pulsed laser light (transmitted light) scanned by the optical head unit 7 and emitted into the atmosphere.

The signal processing unit 5 further changes the airflow carrying the measurement target particles from the calculated amount (concentration) of the measurement target particles, the distance to the measurement target particles, and the change amount of the movement speed of the measurement target particles. That is, the details of the turbulence are calculated.

<Display>
The display 6 displays the occurrence of eddy and its details according to the display signal received from the signal processing unit 5, and issues an alarm.

<Optical head part>
The optical head unit 7 is provided after the transmitting unit 3 and in front of the receiving unit 4.

The optical head portion 7 includes a beam expander 71, a reflective optical phase modulator 72, and a support 73 that supports them. The beam expander 71 is arranged so that the center of the reflective optical phase modulator 72 is on the center line of the beam expander 71. A signal processing unit 5 that finely controls the voltage applied to the reflective optical phase modulator 72 is connected to the reflective optical phase modulator 72. The signal processing unit 5 controls the irradiation timing of the laser light transmitted from the transmission unit 3 and the reflection direction by the reflection type optical phase modulator 72, irradiates the laser light in a desired direction, and receives the reflected light. It is realized to receive at 4.

It is preferable to use a material for the support 73, which has a very small dimensional change (thermal deformation) due to a temperature change. In this example, "LEX-ZERO" (registered trademark), which has a coefficient of thermal expansion of 0 ± 0.19 ppm / K (20 to 25 degrees) and hardly deforms near room temperature, is used.

The beam expander 71 is connected to the port P2 of the circulator 39 of the transmission unit 3 via the large-diameter optical fiber 40a, and the pulsed laser light (transmitted light) output from the port P2 of the optical circulator 39 is large. It is input to the beam expander 71 via the diameter optical fiber 40a.

The beam expander 71 is a lens system for expanding the input pulsed laser light (transmitted light) to a constant magnification while keeping the collimated light (parallel light bundle). Here, the beam expander 71 has a large diameter of 30 μm. The pulsed laser light input via the optical fiber 40a is expanded to collimated light having a beam diameter of about 3 cm.

Then, the collimated light whose diameter is expanded by the beam expander 71 is irradiated toward the reflection type optical phase modulator 72.

≪Reflective optical phase modulator≫
2A and 2B are explanatory views of the reflective optical phase modulator 72, FIG. 2A is a sectional view showing a cross-sectional structure of the reflective optical phase modulator 72, and FIG. 2B is a reflective optical phase. It is a front view which shows the appearance of a modulator 72. FIG. 3 is an explanatory view of the arrangement of the elements 72a of the reflective optical phase modulator 72, and FIG. 3 (A) is a perspective view illustrating the arrangement of the elements 72a of the reflective optical phase modulator 72. FIG. 3B is a vertical sectional view illustrating the orientation of the liquid crystal molecule 72b of the reflective optical phase modulator 72.

The reflection type optical phase modulator 72 is formed to have an overall size of about 3 cm in diameter, has a structure in which a liquid crystal layer 75a is arranged on a Silicon substrate 74a, and includes an address portion 74 and an optical modulation portion 75. There is.

More specifically, in the address portion 74, a CMOS matrix circuit 74b is formed on a silicon substrate 74a, and a plurality of element electrodes 74c are arranged in a plane at equal intervals on the uppermost layer thereof. The arrangement of the element electrodes 74c is, for example, a matrix shape in which the element electrodes 74c are regularly arranged in a grid pattern in the vertical and horizontal directions, or a honeycomb shape in which regular hexagons are arranged without gaps. The interval between the element electrodes 74c is shorter than the wavelength of the laser beam, and more preferably 1/2 or less of the wavelength of the laser beam. As the material of the element electrode 74c, aluminum or the like that reflects laser light with high efficiency is used.

The optical modulation section 75 is arranged above the silicon substrate 74a of the address section 74, and has a liquid crystal layer 75a whose upper and lower sides are sandwiched between liquid crystal alignment films 75d and 75e and whose periphery is surrounded by a sealing material 75g containing a spacer 75f. It is laminated with a glass substrate (transparent substrate) 75c arranged above the layer 75a and having a transparent electrode 75b formed on the lower surface. The liquid crystal alignment films 75d and 75e are for aligning the liquid crystal molecules 72b (see FIG. 3B) in the liquid crystal layer 75a in parallel with the substrates (glass substrate 75c and silicon substrate 74a). Further, the spacer 75f is for making the width of the liquid crystal layer 75a in the vertical direction constant. Further, in the liquid crystal layer 75a, the region corresponding to each element electrode 74c (the upper region of the element electrode 74c) constitutes the element 72a, respectively. That is, the liquid crystal existing in the liquid crystal layer 75a is driven by the element 72a for each element electrode 74c.

A Peltier cooler 76 using a Peltier element is provided below the silicon substrate 74a to control the temperature of the entire reflective optical phase modulator 72.

The voltage of the element electrode 74c can be independently controlled for each element 72a corresponding to the element electrode 74c, whereby the voltage between the element electrode 74c and the transparent electrode 75b can be controlled for each element 72a. Here, when a voltage is gradually applied to the element electrode 74c, the liquid crystal molecule 72b (FIG. 3) directly above the element electrode 74c in the liquid crystal layer 75a, as shown in FIG. 3B, with a certain threshold voltage as a boundary. (See (B)) gradually starts to rise from the horizontal state shown on the right side of FIG. 3 (B) with respect to the substrates 75c and 74a. Then, when a further voltage is applied, the liquid crystal molecules 72b finally become perpendicular to the substrates 75c and 74a as shown on the left side of FIG. 3B. There is a difference in the refractive index of the liquid crystal layer 75a between the state in which the liquid crystal molecules 72b are parallel to the substrates 75c and 74a and the state in which the liquid crystal molecules 72b are perpendicular to the substrates 75c and 74a. Therefore, the laser beam passing through the liquid crystal layer 75a changes the optical path length and causes a phase difference. In other words, when the liquid crystal molecules 72b are parallel to and perpendicular to the substrates 75c and 74a, the passing distance through which the laser beam passes through the liquid crystal molecules 72b changes and a phase difference occurs. That is, the element 72a can modulate the phase of the incident laser light by controlling the voltage applied to the corresponding element electrode 74c. The voltage applied to the element electrode 74c is controlled by a control IC (not shown) by FPGA or the like via a matrix circuit 74b connected to the element electrode 74c. Further, the matrix circuit 74b is provided with a Pad 74d.

The element electrode 74c uses a reflecting member that reflects laser light, and also functions as a reflecting layer for laser light. Therefore, the laser beam incident from the glass substrate 75c side passes through the liquid crystal layer 75a, is reflected by the element electrode 74c arranged on the back surface side of the liquid crystal layer 75a, passes through the liquid crystal layer 75a again in the opposite direction, and then passes through the liquid crystal layer 75a. , Exit from the glass substrate 75c side. In this way, the laser beam incident on the element 72a is reflected by the element electrode 74c and reciprocates through the liquid crystal layer 75a, so that phase modulation is performed twice (about twice).

As shown in FIG. 2B, the reflection type optical phase modulator 72 is composed of a plurality of elements 72a, and the elements 72a are arranged in a plane at equal intervals corresponding to the element electrodes 74c. Since the distance between the element electrodes 74c is shorter than the wavelength of the laser beam, the distance between the elements 72a is also shorter than the wavelength of the laser light.

The collimated light (parallel ray bundle) incident on the reflection type optical phase modulator 72 is phase-modulated and reflected by a plurality of elements 72a arranged at equal intervals in a plane. More specifically, each parallel ray of collimated light (parallel ray bundle) is phase-modulated and reflected by each element 72a on which it is incident. Here, under the control of the signal processing unit 5 (see FIG. 1), the voltage applied to each element electrode 74c of the adjacent element 72a is systematically changed (continuously changed) in the arrangement direction of the element electrode 74c. ) (For example, the voltage is gradually increased or decreased little by little), and the phase of each parallel light beam emitted after reflection by each adjacent element 72a is systematically changed (continuously changed) little by little. That is, the phase of each parallel ray is two-dimensionally modulated by the element 72a arranged in a plane. Then, each parallel ray after reflection whose phase is changed systematically little by little becomes a bundle of parallel rays as a whole according to the Huygens principle, and is different from the normal reflection direction (direction reflected by the mirror) of each parallel ray. It is radiated as a whole in the direction of. That is, parallel rays having slightly different phases interfere with each other, and the entire parallel ray bundle is radiated in a direction in which the phase is advanced (or delayed) from the normal straight direction. Further, by changing the systematic change amount of the applied voltage, the direction of the parallel ray bundle can be changed with respect to the normal reflection direction. The range of this change is an appropriate range, such as setting the angle of the parallel ray bundle around the normal reflection direction to about 15 ° to -15 ° and setting the normal reflection direction as the axis to the entire circumference. be able to.

As shown in FIG. 4A, for example, when the voltage applied to the element electrode 74c of each element 72a of the reflection type optical phase modulator 72 is lowered from right to left, it is incident on the reflection type optical phase modulator 72 and reflected. The radiation direction of the radiation parallel ray bundle emitted later is directed to the left. On the contrary, when the voltage applied to each element electrode 74c is lowered from left to right, the radiation direction of the radiation parallel ray bundle is directed to the right (see FIG. 4B). Similarly, when the voltage applied to each element electrode 74c is lowered from top to bottom, the radiation direction of the radiation parallel light bundle is directed downward (see FIG. 4C), and the voltage applied to each element electrode 74c is changed. When lowered from the bottom to the top, the radiation direction of the radiation parallel ray bundle is directed upward (see FIG. 4 (D)).

With the above configuration, the voltage applied to the element electrode 74c of the element 72a can be systematically controlled by the signal processing unit 5, and the radiation direction of the radiation parallel ray bundle that is incident on the reflection type optical phase modulator 72 and emitted after reflection is Control is possible. The radiation direction of this radiation parallel ray bundle can be changed continuously and arbitrarily. Further, since the radiation direction of the radiation parallel ray bundle is controlled by electrical control, it is possible to change the radiation direction at a higher speed (high-speed scan) than to change the irradiation direction mechanically. For example, it is possible to change the radiation direction about 1000 times per second. Furthermore, since there is no mechanical mechanism, there is little risk of failure, and even when mounted on an aircraft, it is possible to prevent the accuracy from being disturbed by vibration. It should be noted that the radiation direction of the radiation parallel ray bundle can be controlled within 15 degrees of the angle formed by the reflection direction of each parallel ray whose phase is not controlled.

The reflective optical phase modulator 72 is also used to receive the scattered light scattered by the measurement target particles floating in the atmosphere. After radiating the radiation parallel light beam bundle, the reflection type optical phase modulator 72 holds the state for a while (while facing the radiation direction (line-of-sight direction)), and waits for the scattered light to return. After that, when the reflective optical phase modulator 72 receives the scattered light, the received scattered light follows the above-mentioned light path in the reverse direction and is sent to the beam expander 71 (FIGS. 1 to 4). reference). Therefore, the movement of the measurement target particles floating in the atmosphere can be quickly detected.

A Peltier cooler that uses a material for the support 73 of the optical head portion 7 that has a very small dimensional change (thermal deformation) due to a temperature change, and uses a Peltier element to control the temperature of the entire reflective optical phase modulator 72. Since the 76 is used, even if the optical head portion 7 is installed in an environment such as an aircraft where the temperature changes drastically, its performance is not easily impaired.

<Aircraft-mounted Doppler lidar device>
Next, an aircraft-mounted Doppler lidar device and an aircraft equipped with the device will be described.
FIG. 5A is a configuration diagram for explaining the arrangement of the optical head portion of the explanatory view of the aircraft 10 equipped with the Doppler lidar device 1, and FIG. 5B is an explanatory diagram for explaining the airspeed correction. is there.

≪Multi optical head part≫
As shown in FIG. 5A, the Doppler lidar device 1 (see FIG. 1) mounted on the aircraft includes a beam expander 71, a reflective optical phase modulator 72, and a support 73 that supports them. Two sets of the provided optical head portions 7 are installed in the radome 11 at the tip of the aircraft 10.

These two sets of optical head portions 7 are arranged symmetrically, and each reflective optical phase modulator 72 of these optical head portions 7 faces forward or diagonally forward. The directions of the reflective optical phase modulator 72 with respect to the beam expander 71 do not match in these two sets of optical head portions 7. Therefore, the radiation parallel ray bundles emitted by these two sets of optical head portions 7 are emitted in different directions.

Here, the radiation parallel ray bundle that is incident on the reflection type optical phase modulator 72 from the beam expander 71 and is emitted after the reflection is emitted behind the beam expander 71 with the beam expander 71 as an obstacle. Can't. Therefore, in the optical head portion 7, there is an unobservable region 87 behind the beam expander 71 in which eddy is generated and detailed observation cannot be performed.

However, with the above configuration, the unobservable region 87 existing in each optical head 7 can be observed by the optical head 7 on the other side. As a result, in addition to the traveling direction observation range 85 of the aircraft 10, eddy can be observed in a wide range 86 on the traveling direction side.

The two sets of optical heads 7 may be arranged vertically symmetrically, or three or more sets of optical heads 7 may be installed.

≪Airspeed correction≫
As shown in FIG. 5B, the aircraft 10 includes an airspeed acquisition means (speedometer) 83 for acquiring a calibrated airspeed, a calculation means (signal processing unit 5 (see FIG. 1)), and a measurement means. (Signal processing unit 5 (see FIG. 1)) is provided.
The airspeed, which is the relative velocity between the aircraft and the atmosphere, can be obtained from the pressure of the Pitot tube and the static pressure hole mounted on the aircraft. Assuming that the total pressure measured by the Pitot tube is Pt, the static pressure measured from the static pressure hole is Ps, the air density is ρ, and the airspeed is V, V can be obtained by the following [Equation 1].

[Number 1]
V = (2 (Pt-Ps) / ρ) ^1/2
The airspeed acquisition means 83 corrects the mounting position error and the measurement error of the Pitot tube with respect to the above value of V, and acquires the calibrated airspeed.

The signal processing unit 5, which functions as a calculation means, acquires the calibration airspeed in the traveling direction of the aircraft acquired by the airspeed acquisition means 83 of the aircraft 10. Then, as shown in FIG. 5 (B), the radiation direction (line-of-sight direction) 81 (81a to 81d) of the radiation parallel ray bundle emitted from the reflection type optical phase modulator 72 and the traveling direction 82 of the aircraft 10 are formed. Based on the angle θ, the line-of-sight component of the calibrated air velocity is derived.

The signal processing unit 5, which functions as a measuring means, calculates the details of the eddy by the above-mentioned calculation, and based on the Doppler shift of the scattered light from the line-of-sight direction, the line-of-sight direction of the moving speed of the particles to be measured moving on the wind. Measure the components.

The signal processing unit 5 that functions as a calculation means corrects the line-of-sight component of the moving speed of the measurement target particle that moves on the wind by subtracting the line-of-sight component of the calibration airspeed, and wind speed in the wind line-of-sight direction. Is derived.

The output of the laser light source 2 (see FIG. 1) used in the Doppler lidar device 1 mounted on the aircraft is limited. For this reason, the observation range (range) in which scattered light from the particles to be measured can be measured is limited to a certain range, and the wind speed in the direction of the line of sight of the wind is also related to the wind existing in this observation range (range). Limited (see FIG. 5 (B)). Therefore, the Doppler lidar device 1 mounted on the aircraft repeatedly performs measurement at regular intervals while updating the observation range (range) along the traveling direction of the aircraft.

With the above configuration, the Doppler lidar device 1 mounted on the aircraft can acquire the wind speed in the line-of-sight direction of the wind with the airspeed of the aircraft corrected while updating the observation range (range).

≪Eddy warning≫
The Doppler lidar device 1 mounted on the aircraft has a detection means (signal processing unit 5 (see FIG. 1)) that detects the occurrence of eddy based on wind speeds in a plurality of different line-of-sight directions, and the direction in which the detected eddy is generated. , A calculation means (signal processing unit 5 (see FIG. 1)) for calculating the details of the eddy including the distance to the eddy, the scale and strength of the eddy, and a display installed in the cockpit of the aircraft for the details of the eddy. It is provided with an output means (signal processing unit 5 (see FIG. 1)) for outputting to display in 6 (see FIG. 1).

When the detecting means detects the occurrence of eddy, the display 6 displays an alarm notifying the occurrence of eddy. After that, the details of the eddy flow calculated by the calculation means are displayed on the display 6 continuously.

FIG. 6 is a screen configuration diagram showing a screen 90 displayed on the display device 6. Various displays necessary for maneuvering the aircraft 10 are displayed on the screen 90. Among them, the eddy region image 92 showing the region where the turbulence exists is displayed in the front display region 91 that displays the front of the aircraft. The eddy region image 92 has a semi-transparent or opaque filled display so that it is possible to visually recognize whether or not the eddy is rushed into the eddy when flying in the same direction, or how far away from the eddy. Further, the warning display image 93 is displayed in the warning display area at the lower right. In addition to the warning text, the warning display image 93 displays the distance and angle to the position where the eddy is present, the danger level of the eddy, and the like. In this way, the presence of eddy and the condition of eddy are clearly notified to the pilot of the aircraft 10.

With the above configuration, the pilot in the cockpit of the aircraft can know the occurrence of eddy and its details through the indicator 6, and can immediately start the avoidance action, which leads to accident prevention.

Further, when the aircraft 10 lands, it is possible to grasp in real time whether or not the wake turbulence (Wake) caused by the aircraft 10 that landed earlier remains on the landing route. Therefore, it is possible to proceed to the landing route while confirming the existence of the wake turbulence, and if it is likely to reach the wake turbulence before the wake turbulence caused by the aircraft 10 in front is sufficiently weakened, it is possible to temporarily climb and suspend the landing. As a result, it is possible to prevent unintended gas swaying just before landing due to the wake turbulence generated by the preceding aircraft 10, and it is possible to more steadily prevent an accident at the time of landing.

Further, since the pilot can directly confirm the presence or absence of wake turbulence caused by the front aircraft 10 in this way, it is possible to land immediately if wake turbulence does not occur, so that wake turbulence generally disappears. The landing interval caused by guiding the landing of the next aircraft from the controller after a sufficient time can be shortened, and the number of takeoffs and landings of the aircraft 10 on one runway can be increased.

The present invention is not limited to the present embodiment and may be various other embodiments.

The present invention can be applied to industries related to Doppler lidar equipment.

1 ... Doppler lidar device 2 ... Laser light source 3 ... Transmitter 4 ... Receiver 5 ... Signal processing unit 6 ... Display 7 ... Optical head 71 ... Beam expander 72 ... Reflective optical phase modulator

Claims (6)

A laser light source that generates laser light, a radiation unit that radiates the laser light emitted by the laser light source into the atmosphere, and scattered light that is scattered by measurement target particles in which the emitted laser light is suspended in the atmosphere. Equipped with a light receiving part that receives light
A Doppler lidar device that measures the moving speed of the particles to be measured based on the Doppler shift of the scattered light.
A light phase changing means for changing the phase of the incident laser light to change the traveling direction of the light is provided in the subsequent stage of the radiation unit .
The optical phase changing means
It is composed of multiple elements that change the phase of light.
The plurality of elements are arranged in the light plane direction of the incident laser beam.
The optical phase changing means
A liquid crystal layer in which liquid crystals are arranged two-dimensionally,
It is provided with an electrode layer in which a plurality of electrodes are arranged in a matrix.
An applied voltage control means for controlling the voltage applied to the electrodes so as to gradually differ in the arrangement direction of the electrodes is provided.
The liquid crystal in the region corresponding to each electrode is used as the element.
The molecular orientation of each liquid crystal in the liquid crystal layer is gradually changed by a voltage gradually different for each electrode, and the refractive index with respect to the incident laser light is gradually changed for each element by this molecular orientation, and this refractive index is changed. The phase of the laser light is gradually changed for each element depending on the difference in the phase, and the adjacent laser light is interfered with each other due to the difference in the phase to change the overall traveling direction of the laser light.
Doppler lidar device. The optical phase changing means is laminated on the back surface side of the liquid crystal layer, and includes a reflective layer that reflects light incident on the liquid crystal layer.
The Doppler lidar device according to claim 1 . It is provided with two or more optical phase changing means.
The at least one optical phase changing means is configured to radiate the laser beam toward at least a part of the laser beam other than the radiable range of the laser beam by the other optical phase changing means.
The Doppler lidar device according to claim 2 . The elements are arranged at intervals less than the wavelength of the laser beam.
The Doppler lidar device according to any one of claims 1 to 3 . Mounted on an aircraft equipped with airspeed acquisition means to obtain calibrated airspeed,
A measuring means that measures the line-of-sight component of the moving speed of the measurement target particle that moves on the wind based on the Doppler shift of scattered light from the line-of-sight direction.
Further provided with a calculation means for deriving the wind speed in the line-of-sight direction of the wind by subtracting the line-of-sight component of the calibration airspeed from the line-of-sight component of the moving speed.
The Doppler lidar device according to any one of claims 1 to 4 . A detection means for detecting the occurrence of eddy based on the wind speeds in a plurality of different line-of-sight directions,
A calculation means for calculating the details of the eddy including the direction in which the detected eddy occurred, the distance to the eddy, and the scale and strength of the eddy.
Further provided with an output means for outputting the details of the eddy so that it can be displayed on a display in the cockpit of the aircraft.
The Doppler lidar device according to claim 5 .

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