WO2024221628A1 - Cloud particle turbulence synchronous measurement device and method based on digital holography and particle image velocimetry - Google Patents

Abstract

A cloud particle turbulence synchronous measurement device based on digital holography and particle image velocimetry (PIV), comprising a housing (1). A laser emitting arm and a laser receiving arm are arranged on the housing (1), and a sampling area is formed between the two arms. A dual-optical-path holographic measurement unit, a PIV turbulence measurement unit and a control unit (27) are arranged inside the housing (1). The dual-optical-path holographic measurement unit is used for generating two laser beams; one laser beam is transmitted along an original optical path and is emitted by the laser emitting arm, and the other laser beam is redirected and transmitted and is emitted by the laser emitting arm; the two laser beams are incident to the laser receiving arm in a crossed manner through the sampling area and are respectively imaged on two cameras to obtain holographic images. The PIV turbulence measurement unit is used for generating a laser beam to form a sheet light source which is emitted from the laser emitting arm to irradiate a flow field between sampling areas, and acquiring a scattering image of particles. Holographic cloud particle measurement and turbulence measurement can be synchronously realized, and the measurement precision can be improved while the sampling volume is increased. The present invention further relates to a cloud particle turbulence synchronous measurement method based on digital holography and PIV.

Description

Device and method for synchronous measurement of cloud particle turbulence based on digital holography and particle image velocimetry Technical Field

The present invention relates to the technical field of cloud physics measurement, and in particular to a device and method for synchronously measuring cloud particle turbulence based on digital holography and particle image velocimetry.

Background Art

Clouds in the atmosphere cover about 70% of the Earth's surface, and have an important impact on the radiation budget of the earth-atmosphere system and the global water cycle. Many disastrous weather events are also closely related to clouds in the atmosphere. Turbulence in clouds has a huge Reynolds number, and the development and evolution of clouds are affected by turbulence of various scales. The most intuitive manifestation is the various complex microphysical processes experienced by cloud particles, such as condensation, collision, growth, freezing and riming. By synchronously measuring microscopic characteristic parameters such as cloud particle size, concentration, phase state, velocity and shape and turbulent structure parameters, it can help understand the life history of cloud particles, and then infer the interaction between cloud dynamics, thermal dynamics and microphysics, so as to obtain the law of cloud development and evolution, and then realize artificial weather modification and numerical simulation forecasts.

In the prior art, cloud particle measurement is usually carried out using cloud particle measuring instruments. Based on the measurement principle, cloud particle measuring instruments mainly include collision sampling type, optical scattering type and optical imaging type. Among them, the optical scattering type is the most widely used, but the optical scattering type measuring instrument needs to make assumptions about the shape of the particles, and cannot obtain the velocity information of the particles, and cannot directly obtain the phase information of the particles. Digital holography, as an emerging three-dimensional particle field measurement technology, can simultaneously obtain information such as particle size, quantity, speed and shape. In the prior art, holographic particle measuring instruments usually adopt a single-path holographic measurement method, that is, holographic measurement is completed by emitting a light beam. However, this type of single-path holographic measurement method has a small sampling volume, so the cloud particle features that can be collected in each measurement are relatively small, and the accuracy of single-view reconstruction is not high.

In the prior art, the measurement of turbulence in clouds is usually achieved by direct probe using sensors such as ultrasonic anemometers or hot wire anemometers. If cloud particle measurement and cloud turbulence measurement are to be achieved simultaneously, cloud particle measurement instruments and turbulence measurement sensors need to be arranged at the same time. This not only has high implementation costs, but the sensor probes are prone to interfere with flow field measurements, and particle impacts can also reduce sensor sensitivity and increase measurement errors. The method of using sensors to measure turbulence in clouds is not very accurate.

Summary of the invention

The technical problem to be solved by the present invention is as follows: In view of the above-mentioned problems in the prior art, a cloud particle turbulence synchronous measurement device and method based on digital holography and particle image velocimetry with a large sampling volume and high particle measurement accuracy are provided, which can realize cloud particle characteristic measurement with a set of devices, obtain more cloud particle characteristics in a larger sampling volume, and synchronously realize the measurement of turbulent velocity field in the sampling area.

In order to solve the above technical problems, the technical solution adopted by the present invention is:

A synchronous measurement device for cloud particle turbulence based on digital holography and particle image velocimetry comprises a shell, on which a laser emitting arm and a laser receiving arm are arranged, and a sampling area is formed between the laser emitting arm and the laser receiving arm; a dual-light path holographic measurement unit, a PIV turbulence measurement unit and a control unit for overall control are arranged inside the shell; the dual-light path holographic measurement unit is used to generate two laser light beams, one of which is transmitted along the original light path and emitted through the laser emitting arm, and the other is transmitted after being turned and emitted through the laser emitting arm, and after being emitted, the two laser light beams are cross-incident to the laser receiving arm through the sampling area, and are respectively imaged on a camera to obtain holographic images to realize cloud particle feature measurement; the PIV turbulence measurement unit is used to generate a laser light beam to form a sheet light source, which is emitted from the laser emitting arm to irradiate the flow field between the sampling areas, and synchronously realizes turbulent field measurement by collecting scattered images of particles.

Furthermore, the dual-path holographic measurement unit includes a first measurement optical path arranged on the laser emitting arm side and a second measurement optical path arranged on the laser receiving arm side. The first measurement optical path includes a pulse laser, a spatial filter, a collimator, a beam expander, a first color splitter, a beam splitter and two output transmission branches arranged in sequence. The pulse laser emits a laser beam, which passes through the spatial filter and the collimator in sequence and is then expanded by the beam expander. The expanded laser pulse passes through the first color splitter and is divided into two beams of light at the position of the beam splitter. The two output transmission branches respectively transmit the two beams to different output ports of the laser emitting arm for output. The second measurement optical path includes two incident measurement branches, which are used to image the light beams incident through different input ports on a camera respectively.

Furthermore, one of the output transmission branches includes a first reflector, a second color separation mirror, and a first rotating prism arranged in sequence, another of the output transmission branches includes a second reflector and a third reflector arranged in sequence, one of the incident measurement branches includes a fourth reflector, a first lens, and a first camera arranged in sequence, and another of the incident measurement branches includes a second rotating prism, a second lens, and a second camera arranged in sequence; the light beam transmitted along the original optical path passes through the second color separation mirror, turns at the first rotating prism, exits from the first exit port of the laser emitting arm, enters from the first entrance port of the laser receiving arm after passing through the sampling area, and is redirected again by the fourth reflector, and is imaged on the first camera through the first lens; another light beam turned 90° at the beam splitter exits from the second exit port of the laser emitting arm through the first reflector and the third reflector, enters from the second entrance port of the laser receiving arm after passing through the sampling area, and is imaged on the second camera after passing through the second rotating prism and the second lens.

Furthermore, the dual-path holographic measurement unit also includes a timing controller for controlling the working timing of the first camera and the second camera according to a set exposure time sequence when a trigger signal is received, and the trigger signal is generated when the pulse laser emits a laser beam; the dual-path holographic measurement unit also includes a data acquisition and storage unit for acquiring and storing the holographic images recorded by the first camera and the second camera.

Furthermore, the laser emitting arm and the laser receiving arm are symmetrically arranged along the central axis and form a wedge shape with a sharp top. The laser emitting arm and the laser receiving arm are respectively provided with more than two light holes to serve as an exit port and an entrance port, wherein the laser emitting arm is provided with at least three exit ports to respectively emit the two light beams generated by the dual-path holographic measurement unit. The laser receiving arm is provided with at least two incident ends for respectively corresponding to the two light beams generated by the dual-path holographic measurement unit, and a high-reflection material coating is provided on the laser receiving arm opposite to the third exit port (14) on the laser emitting arm for emitting the light sheet generated by the PIV turbulence measurement unit, so that the light sheet generated by the PIV turbulence measurement unit can illuminate the flow field of the sampling area.

Furthermore, the PIV turbulence measurement unit includes a continuous laser, a cylindrical mirror and a third camera. The continuous laser emits a laser beam, which is deflected 90° after passing through a first dichroic mirror, and is transmitted coaxially with the pulsed laser beam emitted by the pulsed laser. After being deflected at the position of the second dichroic mirror by a beam splitter, a light sheet is formed through a cylindrical mirror, and emitted from a corresponding outlet on the laser emitting arm to irradiate the flow field in the sampling area. A high-reflection material coating is provided on the laser receiving arm on the side opposite to the third outlet on the laser emitting arm for emitting the light sheet generated by the PIV turbulence measurement unit, and the scattering image of the particles in the sampling area is recorded by the third camera.

Furthermore, a heat insulation board, a heating unit and a temperature and humidity monitoring unit connected to the control unit are also provided in the shell, and the interior of the shell is divided into multiple areas by the heat insulation board, and multiple temperature and humidity sensors are respectively provided in each divided area; the temperature and humidity monitoring unit monitors the temperature and/or humidity status of each divided area through each of the temperature and humidity sensors, and generates a control signal to the control unit according to the monitored temperature and/or humidity status, wherein when the temperature or humidity is higher than a preset threshold value, a first control signal is generated to the control unit to control the cutting off of the power supply; when the temperature is lower than the preset threshold value, a second control signal is generated to the control unit to control the turning on of the heating unit for heating.

Furthermore, it also includes a balancing tail wing arranged at the tail of the shell and used for overall auxiliary balance during ball-borne measurement. The balancing tail wing includes a connecting rod, an auxiliary tail wing, and a main tail wing which are arranged in sequence. The main tail wing is connected to the shell through a connecting rod and faces the middle position between the laser emitting arm and the laser receiving arm. The auxiliary tail wing is symmetrically arranged on both sides of the main tail wing.

A measurement method using the above-mentioned cloud particle turbulence synchronous measurement device based on digital holography and particle image velocimetry comprises the following steps:

When measuring cloud particle characteristics, a laser beam is emitted by a pulsed laser, passes through the spatial filter and the collimator in sequence, and is then expanded by a beam expander. The expanded laser pulse passes through a first dichroic mirror and is divided into two beams of light at the position of the beam splitter. The light beam transmitted along the original optical path passes through a second dichroic mirror and is turned at a first rotating prism, emitted from a first emission port of a laser emitting arm, and incident from a first incidence port of a laser receiving arm after passing through a sampling area, and is redirected again by a fourth reflector, and is imaged on a first camera through a first lens to obtain a holographic image. Another light beam turned 90° at the beam splitter is emitted from a second emission port of the laser emitting arm through a first reflector and a third reflector, and incident from a second incidence port of the laser receiving arm after passing through a sampling area, and is imaged on a second camera through a second rotating prism and a second lens to obtain a holographic image.

When performing turbulence measurement, a laser beam is emitted by a continuous laser, which is deflected 90° after passing through the first dichroic mirror and transmitted coaxially with the pulsed laser beam emitted by the pulsed laser. After being deflected by the beam splitter at the position of the second dichroic mirror, it is emitted from the corresponding outlet on the laser emitting arm to illuminate the flow field in the sampling area, and the scattering image of the particles is recorded by the third camera.

Furthermore, the cloud particle characteristic measurement also includes a step of fusing the holograms obtained by the dual light paths, and the specific steps include:

Establish a coordinate system, in which the coordinate system corresponding to the optical path of the continuous laser in the sampling area is recorded as (x, y, z), and the coordinate systems of the two optical paths generated by the pulsed laser are recorded as (x ₁ , y ₁ , z ₁ ) and (x ₂ , y ₂ , z ₂ );

After obtaining the particle information based on the holographic images recorded by the two optical paths, the particle information is uniformly converted to the coordinate system corresponding to the continuous laser according to the following formula to obtain the final three-dimensional particle field characteristics:

Wherein, θ is the angle between the two coordinate systems, and C _x , _Cy and C _z are the coordinate translation coefficients related to the angle θ.

Compared with the prior art, the advantages of the present invention mainly include: the present invention forms a sampling area by arranging a laser emitting arm and a laser receiving arm on a shell, and arranging a dual-path holographic measurement unit inside the shell. The dual-path holographic measurement unit adopts a dual-path measurement structure to realize dual-path digital coaxial holographic measurement, which can quickly and accurately collect cloud particle holographic images, thereby realizing synchronous measurement of characteristics such as size, quantity, shape, phase and velocity of cloud particles in the sampling area, and based on the dual-path structure, the sampling volume can be effectively increased, thereby effectively increasing the collected cloud particle characteristics; at the same time, a PIV turbulence measurement unit is also arranged in the shell, and synchronous measurement of the flow field in the sampling area between the two arms can avoid measurement interference and improve measurement accuracy, and a set of devices can be used to synchronously realize cloud particle characteristic measurement and sampling area flow field measurement, which can ensure measurement accuracy while reducing implementation costs and improving measurement flexibility, so that accurate cloud particle microphysical processes under the influence of turbulence can be conveniently obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of a cloud particle turbulence synchronous measurement device based on digital holography and particle image velocimetry in an embodiment of the present invention.

FIG. 2 is a schematic diagram of cross-sampling region data fusion coordinates in an embodiment of the present invention.

FIG3 is a flow chart of a cross-sampling region data fusion method according to an embodiment of the present invention.

Legend:
1. Shell; 2. Pulse laser; 3. Spatial filter; 4. Collimator; 5. Beam expander; 6. First dichroic mirror; 7.
first reflector; 8, beam splitter; 9, second reflector; 10, third camera; 11, reflector; 12, second exit port; 13, second dichroic mirror; 14, third exit port; 15, second exit port; 16, first rotating prism; 17, second rotating prism; 18, second entrance port; 19, first lens; 20, second camera; 21, first entrance port; 22, fourth reflector; 23, second lens; 24, first camera; 25, continuous laser; 26, timing controller; 27, control unit; 28, digital Data acquisition card; 29. Solid-state hard disk; 30. Signal transmission card; 31. Temperature and humidity monitoring unit; 32. Power supply unit; 33. Navigation and positioning unit; 34. Connecting rod; 35. Aileron; 36. Main empennage; 37. Heat insulation board.

DETAILED DESCRIPTION

The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

As shown in Figures 1 to 3, the cloud particle turbulence synchronous measurement device based on digital holography and particle image velocimetry in this embodiment includes a shell 1, on which a laser emitting arm and a laser receiving arm are arranged, and a sampling area is formed between the laser emitting arm and the laser receiving arm; a dual-light path holographic measurement unit, a PIV turbulence measurement unit and a control unit 27 for overall control are arranged inside the shell 1; the dual-light path holographic measurement unit is used to generate two laser light beams, one of which is transmitted along the original light path and emitted through the laser emitting arm, and the other is transmitted after being turned and emitted through the laser emitting arm, and after the two laser light beams are emitted, they are cross-incident to the laser receiving arm through the sampling area, and are imaged on a camera respectively to obtain holographic images to realize cloud particle feature measurement; the PIV (particle image velocimetry) turbulence measurement unit is used to generate a laser beam to form a light source, which is emitted from the laser emitting arm to illuminate the flow field between the sampling areas, and synchronously realizes turbulent field measurement by collecting scattered images of particles.

In this embodiment, a sampling area is formed by arranging a laser emitting arm and a laser receiving arm on a shell 1, and a dual-path holographic measurement unit is arranged inside the shell 1. The dual-path holographic measurement unit adopts a dual-path measurement structure to realize dual-path digital coaxial holographic measurement, which can quickly and accurately collect cloud particle holographic images, thereby realizing synchronous measurement of characteristics such as size, quantity, shape, phase and velocity of cloud particles in the sampling area, and based on the dual-path structure, the sampling volume can be effectively increased, thereby effectively increasing the collected cloud particle characteristics; at the same time, a PIV turbulence measurement unit is also arranged in the shell 1, and synchronous measurement of the flow field in the sampling area between the two arms can avoid measurement interference and improve measurement accuracy. Moreover, a set of devices can be used to synchronously realize cloud particle characteristic measurement and sampling area flow field measurement, which can ensure measurement accuracy while reducing implementation costs and improving measurement flexibility, so that accurate cloud particle microphysical processes under the influence of turbulence can be conveniently obtained.

In this embodiment, the dual-path holographic measurement unit specifically includes a first measurement optical path arranged on the laser emitting arm side and a second measurement optical path arranged on the laser receiving arm side. The first measurement optical path includes a pulse laser 2, a spatial filter 3, a collimator 4, a beam expander 5, a first color splitter 6, a beam splitter 8 and two output transmission branches arranged in sequence. The pulse laser 2 emits a laser beam, which passes through the spatial filter 3 and the collimator 4 in sequence and is then expanded by the beam expander 5. The expanded laser pulse passes through the first color splitter 6 and is divided into two beams of light at the position of the beam splitter 8. The two output transmission branches transmit the two beams to different output ports of the laser emitting arm for output respectively. The second measurement optical path includes two incident measurement branches, which are used to image the light beams incident through different input ports on a camera respectively.

Preferably, the pulse laser 2 can specifically be a 355nm pulse laser.

Preferably, when beam splitting is performed at the position of the beam splitter 8, the intensity ratio of the two laser beams is 1:1, that is, the two beams are split into two beams with the same intensity, so as to ensure that the two holographic measurement sampling beams have the same sampling capacity.

In this embodiment, of the two outgoing transmission branches of the dual-path holographic measurement unit, one outgoing transmission branch includes a first reflector 9, a second dichroic mirror 13, and a first rotating prism 16 arranged in sequence, and the other outgoing transmission branch includes a second reflector 7 and a third reflector 11 arranged in sequence, one incident measurement branch includes a fourth reflector 22, a first lens 23, and a first camera 24 arranged in sequence, and the other incident measurement branch includes a second rotating prism 17, a second lens 19, and a second camera 20 arranged in sequence; the light beam transmitted along the original light path passes through the second dichroic mirror 13. After that, it turns at the first rotating prism 16, emerges from the first exit port 15 of the laser emitting arm, enters the first entrance port 21 of the laser receiving arm after passing through the sampling area, and is changed in direction by the fourth reflecting mirror 22 again, and is imaged on the first camera 24 through the first lens 23; another light beam turns 90° at the beam splitter 8, emerges from the second exit port 12 of the laser emitting arm through the first reflecting mirror 7 and the third reflecting mirror 11, enters the second entrance port 18 of the laser receiving arm after passing through the sampling area, and is imaged on the second camera 20 after passing through the second rotating prism 17 and the second lens 19.

Preferably, the first camera 24 and the second camera 20 can be CCD cameras. The first lens 23 and the second lens 19 can be telecentric lenses.

In this embodiment, the dual-path holographic measurement unit also includes a sequence controller 26, which is used to control the working timing of the first camera 24 and the second camera 20 according to the set exposure time sequence when a trigger signal is received. The trigger signal is generated when the pulse laser 2 emits a laser beam, that is, the pulse laser 2 emits a laser beam and outputs a trigger signal to the timing controller 26, which controls the first camera 20 and the second camera 24 to work according to the set exposure time sequence.

In this embodiment, the dual-path holographic measurement unit further includes a data acquisition and storage unit for acquiring and storing the holographic images recorded by the first camera 24 and the second camera 20. The data acquisition and storage unit specifically includes a data acquisition card 28, a signal transmission card 30 and a solid state hard disk 29. The holograms recorded by the first camera 24 and the second camera 20 are transmitted to the data acquisition card 28, and after image conversion and compression, they are stored in the solid state hard disk 29. According to the recorded holographic images, characteristic information such as particle size, shape, and speed can be obtained.

In this embodiment, a fixing plate is also provided inside the housing 1 for fixing the components, and the housing 1 and the internal fixing plate can form an effective protective structure. The tip of the housing 1 can be further formed into a wedge shape with a sharp top, the housing 1 and the measuring arms are integrally cast and divided into upper and lower halves, the fixing plate is fixed to the lower half of the device housing 1 by a threaded nut, and the fixing plate has engineering threaded holes for fixing other accessories of the device.

Preferably, the laser emitting arm and the laser receiving arm are symmetrically arranged along the central axis, and the laser emitting arm and the laser receiving arm are respectively provided with more than two light holes (optical windows) to serve as the exit and the entrance, respectively, wherein the laser emitting arm is provided with at least three exit ports to respectively emit the two light beams generated by the dual-path holographic measurement unit and the light sheet generated by the PIV turbulence measurement unit, the first exit port 15 and the second exit port 12 correspond to the two light beams generated by the dual-path holographic measurement unit, the third exit port 14 corresponds to the light sheet generated by the PIV turbulence measurement unit, and the laser receiving arm is provided with at least two incident ends (the first incident end 21 and the second incident end 18) to respectively correspond to the two light beams generated by the incident dual-path holographic measurement unit. A high-reflection material coating is provided on the laser receiving arm on the side opposite to the third outlet 14 on the laser emitting arm, so that the light sheet generated by the PIV turbulence measurement unit illuminates the flow field in the sampling area.

Preferably, all optical windows on the laser transmitting arm and the laser receiving arm are sealed with sapphire to reduce the influence of stray light and reduce water vapor condensation. Furthermore, some or all of the optical windows are also provided with heating resistance wires. During the measurement process, the resistance wires around the optical windows are turned on at specified intervals to heat the optical windows for a specified period of time to prevent condensation of water vapor or frost.

In this embodiment, the PIV turbulence measurement unit specifically includes a continuous laser 25, a cylindrical mirror and a third camera 10. The continuous laser 25 emits a laser beam, which is deflected 90° after passing through the first dichroic mirror 6, and is coaxially transmitted with the pulsed laser beam emitted by the pulsed laser 2. After being deflected at the position of the second dichroic mirror 13 by the beam splitter 8, a sheet light source is formed through the cylindrical mirror, and then emitted from the corresponding exit port on the laser emitting arm. The high-reflection material coating provided on the laser receiving arm is used to make the formed sheet light source illuminate the flow field of the sampling area, and the third camera 10 records the scattering image of the particles.

Preferably, in this embodiment, the continuous laser 25 is a 532 nm continuous laser, and the third camera 10 can be a high-speed camera.

Optionally, in addition to the above-mentioned structure of coaxial transmission of holographic measurement and turbulence measurement, other methods of holographic measurement and turbulence measurement can also be adopted. For example, the pulse laser 2 used in the holographic measurement is a 532nm pulse laser, and the holographic measurement optical path and the PIV turbulence measurement optical path are not coaxially transmitted, but staggered at a certain height difference, with the holographic 532nm laser beam transmission path at the bottom and the PIV turbulence 532nm laser beam at the top.

In this embodiment, a heat insulation board 37, a heating unit, and a temperature and humidity monitoring unit connected to the control unit 27 are also provided in the housing 1. The interior of the housing 1 is divided into multiple areas by the heat insulation board 37, and multiple temperature and humidity sensors are respectively provided in each divided area; the temperature and humidity monitoring unit 31 monitors the temperature and/or humidity state of each divided area through each temperature and humidity sensor, and generates a control signal to the control unit 27 according to the monitored temperature and/or humidity state, wherein when the temperature or humidity is higher than a preset first threshold value, a first control signal is generated to the control unit 27 to control the power supply to be cut off; when the temperature is lower than a second preset threshold value, a second control signal is generated to the microcomputer control unit 27 to control the heating unit to be turned on for heating. The temperature and humidity monitoring unit 31 can specifically adopt a temperature control chip. The above-mentioned heating unit can specifically adopt a thermal resistance wire, etc.

Specifically, the pulse laser 2, the second camera 24 and the image recording and acquisition device 10 are divided into separate areas by the heat insulation plate 37, and temperature and humidity sensors are arranged inside each area; when the pulse laser 2 and the continuous laser 25 are working, the temperature and humidity monitoring unit 31 is controlled according to the values displayed by the temperature and humidity sensors inside the device, wherein when the internal temperature is higher than the first preset threshold, the temperature and humidity monitoring unit 31 outputs a signal to the control unit 27, the control unit 27 cuts off the power supply, and the pulse laser 2, the continuous laser 25, the first camera 24 and the second camera 20 stop working; when the internal temperature is lower than the second preset threshold, the temperature and humidity monitoring unit 31 outputs a signal to the control unit 27, and the control unit 27 turns on the resistance wire to heat the inside of the device. When the internal humidity is greater than the third preset threshold, it indicates that there may be a water vapor leak, and the temperature and humidity monitoring unit 31 outputs a signal. The signal is sent to the control unit 27, the control unit 27 cuts off the power supply, the pulse laser 2, the continuous laser 25, the first camera 24 and the second camera 20 stop working, and the control unit 27 controls the signal transmitter card 30 to send a warning signal to the ground to protect the internal optical device. Preferably, the first preset threshold can be set to 40°, the second preset threshold can be set to 10°, and the third preset threshold can be set to 75%, which can be configured according to actual needs.

In this embodiment, a balancing tail wing is also included, which is arranged at the tail of the housing 1 and is used for overall auxiliary balance during ball-borne measurement. The balancing tail wing includes a connecting rod 34, an auxiliary tail wing 35, and a main tail wing 36, which are arranged in sequence. The main tail wing 36 is connected to the housing 1 through the connecting rod 34 and faces the middle position between the laser transmitting arm and the laser receiving arm. The auxiliary tail wing 35 is symmetrically arranged on both sides of the main tail wing 36. By setting up a tail wing balancing mechanism, stable measurement of the instrument during ball-borne aerial detection can be assisted.

Furthermore, in this embodiment, a lithium battery as a power supply unit 32 for supplying power to all devices of the device is provided inside the housing 1, as well as a navigation and positioning unit 33 for navigation and positioning of the device.

The present invention utilizes the above-mentioned cloud particle turbulence synchronous measurement method based on digital holography and particle image velocimetry, comprising the following steps:

When measuring the characteristics of cloud particles, a laser beam is emitted by a pulsed laser 2, and after passing through a spatial filter 3 and a collimator 4 in sequence, it is expanded by a beam expander 5. After the expanded laser pulse passes through a first dichroic mirror 6, it is divided into two beams of light at the position of a beam splitter 8; the light beam transmitted along the original optical path passes through a second dichroic mirror 13, and is turned at a first rotating prism 16, and is emitted from a first emission port of a laser emitting arm, and is incident from a first incident port of a laser receiving arm after passing through a sampling area, and is redirected again by a fourth reflector 22, and is imaged on a first camera 24 through a first lens 23 to obtain a holographic image; another light beam that is turned 90° at the beam splitter 8 is emitted from a second emission port of the laser emitting arm through a first reflector 7 and a third reflector 11, and is incident from a second incident port of the laser receiving arm after passing through a sampling area, and is imaged on a second camera 20 through a second rotating prism 17 and a second lens 19 to obtain a holographic image;

When performing turbulence measurement, a laser beam is emitted by a continuous laser 25, which is deflected 90° after passing through the first dichroic mirror 6, and is transmitted coaxially with the pulsed laser beam emitted by the pulsed laser 2. After being deflected by the beam splitter 8 at the position of the second dichroic mirror 13, it is emitted from the corresponding outlet on the laser emitting arm to irradiate the flow field in the sampling area, and the scattering image of the particles is recorded by the third camera 10.

As shown in FIGS. 2 and 3 , the cloud particle feature measurement in this embodiment further includes a step of fusing the holograms obtained by the dual light paths, and the specific steps include:

A coordinate system is established, as shown in FIG3 , in which the coordinate system corresponding to the optical path of the continuous laser 25 in the sampling area is recorded as (x, y, z), and the coordinate systems of the two optical paths generated by the pulsed laser 2 are recorded as (x ₁ , y ₁ , z ₁ ) and (x ₂ , y ₂ , z ₂ );

After obtaining the particle information according to the holographic images recorded by the two optical paths, the particle information is uniformly converted to the coordinate system corresponding to the continuous laser 25 according to the following formula to obtain the final three-dimensional particle field characteristics:

Among them, θ is the angle between the two coordinate systems, and _Cx , _Cy and _Cz are the coordinate translation coefficients related to the angle θ. When the optical path is fixed, _Cx , _Cy , _Cz and θ are all constants and can be obtained through experimental measurement.

In this embodiment, particle information is first obtained according to the first optical path holographic image and the second optical path holographic image, and the particle information obtained from the first optical path holographic image and the second optical path holographic image is subjected to coordinate conversion according to formula (1) and then particle matching is performed with the particle information of the first optical path holographic image. Alternatively, the second optical path holographic image can be subjected to coordinate conversion to be consistent with the first optical path holographic image and then particle matching is performed (as shown in FIG. 2 ), and finally a three-dimensional particle field feature is obtained. Using the measurement results of the double optical path intersection area, the measurement accuracy of the particle feature can be further improved by a data fusion method.

The above are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims (10)

A cloud particle turbulence synchronous measurement device based on digital holography and particle image velocimetry, characterized in that it comprises a shell (1), wherein a laser emitting arm and a laser receiving arm are arranged on the shell (1), and a sampling area is formed between the laser emitting arm and the laser receiving arm; a dual-light path holographic measurement unit, a PIV turbulence measurement unit and a control unit (27) for overall control are arranged inside the shell (1); the dual-light path holographic measurement unit is used to generate two laser light beams, one of which is transmitted along the original light path and emitted through the laser emitting arm, and the other is transmitted after being diverted and emitted through the laser emitting arm, and after being emitted, the two laser light beams are cross-incident to the laser receiving arm through the sampling area, and are respectively imaged on a camera to obtain a holographic image to realize cloud particle feature measurement; the PIV turbulence measurement unit is used to generate a laser light beam to form a sheet light source, which is emitted from the laser emitting arm and irradiates the flow field between the sampling areas, and synchronously realizes turbulence field measurement by collecting scattered images of particles. The cloud particle turbulence synchronous measurement device based on digital holography and particle image velocimetry according to claim 1 is characterized in that the dual-optical path holographic measurement unit comprises a first measurement optical path arranged on the laser emitting arm side and a second measurement optical path arranged on the laser receiving arm side, the first measurement optical path comprises a pulse laser (2), a spatial filter (3), a collimator (4), a beam expander (5), a first colorimetric mirror (6), a beam splitter (8) and two outgoing transmission branches arranged in sequence, the pulse laser (2) emits a laser beam, which is sequentially expanded by the beam expander (5) after passing through the spatial filter (3) and the collimator (4), the laser pulse after the beam expansion passes through the first colorimetric mirror (6) and is divided into two beams at the position of the beam splitter (8), and the two outgoing transmission branches respectively transmit the two beams to different exit ports of the laser emitting arm for exit, and the second measurement optical path comprises two incident measurement branches for imaging the beams incident through different entrance ports on a camera respectively. According to claim 2, the synchronous measurement device for cloud particle turbulence based on digital holography and particle image velocimetry is characterized in that one of the outgoing transmission branches includes a first reflector (9), a second dichroic mirror (13), and a first rotating prism (16) arranged in sequence, another of the outgoing transmission branches includes a second reflector (7) and a third reflector (11) arranged in sequence, one of the incident measurement branches includes a fourth reflector (22), a first lens (23), and a first camera (24) arranged in sequence, and another of the incident measurement branches includes a second rotating prism (17), a second lens (19), and a second camera (20) arranged in sequence; the light beam transmitted along the original optical path passes through the second dichroic mirror (1 3), turns at the first rotating prism (16), is emitted from the first emission port (15) of the laser emitting arm, enters the first incidence port (21) of the laser receiving arm after passing through the sampling area, and is again changed in direction by the fourth reflecting mirror (22), and is imaged on the first camera (24) through the first lens (23); another beam of light turns 90° at the beam splitter (8), is emitted from the second emission port (12) of the laser emitting arm through the first reflecting mirror (7) and the third reflecting mirror (11), enters the second incidence port (18) of the laser receiving arm after passing through the sampling area, and is imaged on the second camera (20) after passing through the second rotating prism (17) and the second lens (19). According to the cloud particle turbulence synchronous measurement device based on digital holography and particle image velocimetry according to claim 2, The dual-light path holographic measurement unit is characterized in that the dual-light path holographic measurement unit further includes a timing controller (26) for controlling the working timing of the first camera (24) and the second camera (20) according to a set exposure time sequence when a trigger signal is received, and the trigger signal is generated when the pulse laser (2) emits a laser beam; the dual-light path holographic measurement unit further includes a data acquisition storage unit for acquiring and storing the holographic images recorded by the first camera (24) and the second camera (20). According to claim 1, the synchronous measurement device for cloud particle turbulence based on digital holography and particle image velocimetry is characterized in that the laser emitting arm and the laser receiving arm are symmetrically arranged along the central axis and form a wedge shape with a sharp top, and the laser emitting arm and the laser receiving arm are respectively provided with more than two light holes to serve as an exit port and an entrance port, wherein the laser emitting arm is provided with at least three exit ports to respectively emit the two light beams generated by the dual-path holographic measurement unit and the light sheet generated by the PIV turbulence measurement unit, and the laser receiving arm is provided with at least two incident ends to respectively correspond to the two light beams generated by the dual-path holographic measurement unit, and a high-reflection material coating is provided on the laser receiving arm on the side opposite to the third exit port (14) on the laser emitting arm for emitting the light sheet generated by the PIV turbulence measurement unit, so that the light sheet generated by the PIV turbulence measurement unit illuminates the flow field of the sampling area. According to any one of claims 1 to 5, the cloud particle turbulence synchronous measurement device based on digital holography and particle image velocimetry is characterized in that the PIV turbulence measurement unit comprises a continuous laser (25), a cylindrical mirror and a third camera (10), the continuous laser (25) emits a laser beam, which is deflected 90° after passing through a first dichroic mirror (6), and is coaxially transmitted with the pulsed laser beam emitted by the pulsed laser (2), and is deflected at the position of the second dichroic mirror (13) through a beam splitter (8) and then formed into a light sheet through a cylindrical mirror, and is emitted from the corresponding exit port on the laser emitting arm to illuminate the flow field of the sampling area, wherein a high-reflection material coating is provided on the laser receiving arm on the side opposite to the third exit port (14) on the laser emitting arm for emitting the light sheet generated by the PIV turbulence measurement unit, and the scattered image of the particles in the sampling area is recorded by the third camera (10). According to any one of claims 1 to 5, the synchronous measurement device for cloud particle turbulence based on digital holography and particle image velocimetry is characterized in that a heat insulation board (37), a heating unit and a temperature and humidity monitoring unit (31) connected to the control unit (27) are also arranged in the shell (1), and the interior of the shell (1) is divided into multiple areas by the heat insulation board (37), and multiple temperature and humidity sensors are respectively arranged in each divided area; the temperature and humidity monitoring unit (31) monitors the temperature and/or humidity state of each divided area through each of the temperature and humidity sensors, and generates a control signal to the control unit (27) according to the monitored temperature and/or humidity state, wherein when the temperature or humidity is higher than a preset threshold value, a first control signal is generated to the control unit (27) to control the power supply to be cut off; when the temperature is lower than the preset threshold value, a second control signal is generated to the control unit (27) to control the heating unit to be turned on for heating. The cloud particle turbulence synchronous measurement device based on digital holography and particle image velocimetry according to any one of claims 1 to 5 is characterized in that it also includes a balancing tail wing arranged at the tail of the shell (1) for overall auxiliary balance during ball-borne measurement, and the balancing tail wing includes a connecting rod (34), an auxiliary tail wing (35), and a main tail wing (36) arranged in sequence, The main tail wing (36) is connected to the housing (1) via a connecting rod (34) and faces the middle position between the laser emitting arm and the laser receiving arm, and the auxiliary tail wing (35) is symmetrically arranged on both sides of the main tail wing (36). A measurement method using the cloud particle turbulence synchronous measurement device based on digital holography and particle image velocimetry according to any one of claims 1 to 8, characterized in that it comprises the following steps: When measuring cloud particle characteristics, a laser beam is emitted by a pulsed laser (2), passes through the spatial filter (3) and the collimator (4) in sequence, and is then expanded by a beam expander (5). The expanded laser pulse passes through a first dichroic mirror (6) and is then split into two beams at the position of a beam splitter (8); the light beam transmitted along the original optical path passes through a second dichroic mirror (13), is deflected at a first rotating prism (16), and is emitted from a first emission port of a laser emitting arm, passes through a sampling area, and is then emitted from a first inlet port of a laser receiving arm. The light beam is incident from the laser beam outlet and redirected by the fourth reflector (22) again, and is imaged on the first camera (24) through the first lens (23) to obtain a holographic image; another light beam is turned 90 degrees at the beam splitter (8), and is emitted from the second emission outlet of the laser emitting arm through the first reflector (7) and the third reflector (11), and is incident from the second incidence outlet of the laser receiving arm after passing through the sampling area, and is imaged on the second camera (20) after passing through the second rotating prism (17) and the second lens (19) to obtain a holographic image; When turbulence measurement is performed, a laser beam is emitted by a continuous laser (25), deflected by 90° after passing through a first dichroic mirror (6), and transmitted coaxially with a pulsed laser beam emitted by a pulsed laser (2). After being deflected at the position of a second dichroic mirror (13) by a beam splitter (8), the laser beam is emitted from a corresponding emission port on a laser emission arm to illuminate a flow field in a sampling area, and a scattering image of particles is recorded by a third camera (10). The measurement method according to claim 9 is characterized in that the cloud particle characteristic measurement further includes a step of fusing the holograms obtained by the dual light paths, and the specific steps include: A coordinate system is established, wherein the coordinate system corresponding to the optical path of the continuous laser (25) in the sampling area is recorded as (x, y, z), and the coordinate systems of the two optical paths generated by the pulsed laser (2) are recorded as (x ₁ , y ₁ , z ₁ ) and (x ₂ , y ₂ , z ₂ ); After obtaining the particle information based on the holographic images recorded by the two optical paths, the particle information is uniformly converted to the coordinate system corresponding to the continuous laser (25) according to the following formula to obtain the final three-dimensional particle field characteristics:
Wherein, θ is the angle between the two coordinate systems, and C _x , _Cy and C _z are the coordinate translation coefficients related to the angle θ.