CN118244379A - Local area atmospheric turbulence measurement method based on laser wavefront arrival angle fluctuation - Google Patents
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Abstract
The invention provides a local area atmospheric turbulence measuring method based on fluctuation of an arrival angle of a laser wave front, which relates to the technical field of atmospheric optical measurement, and the method comprises the steps of dividing light from a single laser source into multiple paths through an optical fiber beam splitter to form laser beam arrays with different base line lengths (B); an imaging telescope with higher resolution and a high-speed CMOS acquisition camera are adopted as a receiving device to capture laser spot images after passing through atmospheric turbulence; the atmospheric turbulence can distort and undulate the wave front arrival angle of the laser, so that the center of an imaged laser spot image is offset; the profile data of the atmospheric turbulence can be obtained in real time by measuring the deviation of the laser spot centers on different base lines and calculating the covariance of the arrival angles of the laser wave fronts with different base line lengths; based on the fluctuation variance and covariance of the arrival angle of the laser wave front, the intensity and the height distribution of the atmospheric turbulence are deduced, and the atmospheric turbulence parameters can be stably measured for a long time.
Description
Technical Field
The invention relates to the technical field of atmospheric optical measurement, in particular to a local area atmospheric turbulence measurement method based on laser wavefront arrival angle fluctuation.
Background
Local regional turbulence, such as turbulence (Dome Seeing) in the dome of the telescope, turbulence (Tube Seeing) in the laboratory and telescope barrels or channels, and what we often say is specular (Mirror Seeing), can also have a significant impact on the imaging quality of the telescope. Therefore, how to perform qualitative measurement of the atmospheric optical turbulence parameters of the near-ground local area and analyze the specific turbulence profile structure are all fundamental works of importance for telescope construction and improvement of facilities, especially for large telescope based on adaptive optical technology.
Currently, the measurement means of the atmospheric optical turbulence parameters can be roughly classified into a wavefront arrival angle detection method, a scintillator method, a micro-temperature pulsation detection method, a sodar detection method, and the like. Among them, the detection of the wave front arrival angle is the most commonly used method for detecting the atmospheric optical turbulence, which calculates the atmospheric turbulence intensity through the relative fluctuation of the star image wave front arrival angle inclination, and the main representative examples are: DIMM (DIFFERENTIAL IMAGE Motion Monitor) and S-DIMM (Solar DIFFERENTIAL IMAGE Motion Monitor) are respectively the most classical night and birthweight measuring devices, and are the most important measuring devices in astronomical site selection. However, they measure the integrated effect of the entire layer of atmospheric turbulence, and cannot measure the near-ground layer, and even more cannot measure local atmospheric turbulence. The scintillation method is to measure the scintillation change of the starlight intensity to calculate the turbulence intensity of the atmosphere. The detection devices of this type are: MASS (Multi-Aperture Scintillation Sensor), SCIDAR (Scintillation Detection AND RANGING), SHABAR (Shadow Band Array), and the like. Wherein MASS and SCIDAR can obtain turbulent atmospheric refractive index structural constants at nightAnd atmospheric coherence time/>Angle of isochroneIsoparametric, SHABAR is a scintillator array, and turbulence atmosphere refractive index structural constant/>, is realized by observing large surface source targets such as sun or moonIs a measurement of (a). Their measurements reflect more of the overall turbulence atmosphere profile with altitude, lacking the detailed information required for atmospheric turbulence in local areas near the ground. Sodar detection is a new method of atmospheric turbulence structure measurement developed over the last decades and is an important means of detecting the atmospheric boundary layer. The method can be used for acquiring a plurality of important atmospheric boundary layer parameters such as wind, temperature, turbulence statistical characteristic profile and the like, is relatively suitable for regional outdoor near-ground atmospheric turbulence detection, but is not flexible and economical for measuring turbulence characteristics such as Dome seeing, tube Seeing, mirror Seeing and the like. Micro-temperature detection is another classical measurement mode of atmospheric optical parameters of turbulent flow, and the characteristic of atmospheric turbulent flow is inverted by detecting the change of local temperature, so that the method can measure the atmospheric refractive index structural constant/>The turbulent atmospheric pressure profile of the near-formation may be measured directly after being lifted off with a balloon or other means. It is the main equipment of measuring near ground local area atmospheric turbulence at present, but because it adopts the platinum silk of 10um as the detector, very easily breaks, and in addition itself is very easily polluted (like the condition that dust covers on the platinum silk) and influences its SNR, so hardly as the equipment of long-term near ground turbulence monitoring.
From the above description, although the current detection means of turbulent atmosphere optical characteristics are abundant, the measurement of atmospheric turbulence in local areas such as Local Seeing, dome Seeing, tube Seeing and Mirror Seeing near the ground is not very effective in detection means other than the micro-temperature pulser. With the development of optical, laser and optical fiber detection technologies, many researchers at home and abroad begin to measure the optical turbulence characteristics of the atmosphere by utilizing the laser wavefront detection technology. Optical fiber measurement systems with single air gap atmosphere optical turbulence characteristics based on the optical fiber Mach-Zehnder interferometry principle are proposed as Mei Haiping, rao Ruizhong professor and the like of Anhui optical machines of national academy of sciences; foreign s.cavazzani et al, university of Padova, italy, propose a measurement model for laser detection of near-surface atmospheric optical turbulence, which uses the reflected echo characteristics of the laser to make near-surface atmospheric turbulence measurements.
Therefore, based on the method for measuring the optical turbulence characteristics of the atmosphere by the laser wavefront detection, combining with the characteristics of high intensity, high monochromaticity, high coherence, high directivity and the like of the laser, the method for measuring the local turbulence characteristics of the atmosphere by utilizing the fluctuation of the wavefront arrival angles of the parallel laser beams with different baselines is provided according to the transmission characteristics of the laser under the turbulent atmosphere, so as to be suitable for measuring the local turbulence of the atmosphere in different occasions.
Disclosure of Invention
In view of this, the invention aims to propose a local area atmospheric turbulence measurement method based on laser wavefront arrival angle fluctuation, which can measure local area atmospheric turbulence characteristics by measuring the fluctuation of the laser wavefront arrival angle, and can measure local atmospheric turbulence by measuring covariance of laser wavefront arrival angles of different baselines and by measuring fluctuation of wavefront arrival angles of parallel laser beams of different baselines, wherein the receiving light spot can flash and drift (distortion caused by laser wavefront arrival angle fluctuation) after laser passes through a turbulent medium due to the influence of atmospheric turbulence. The local area atmospheric turbulence measurement technology based on the fluctuation of the arrival angle of the laser wave front can be suitable for local atmospheric turbulence measurement of different occasions, has a less complex structure, and can realize long-term stable measurement of atmospheric turbulence parameters of local areas such as astronomical domes, optical laboratories, near-stratum and the like. The invention realizes the measurement of the atmospheric turbulence parameters of the local area by utilizing the characteristics of high monochromaticity, high coherence, high directivity and the like of the laser light source, so that the invention has a series of advantages of better anti-interference and stronger adaptability and the like.
The invention is realized by adopting the following technical scheme:
in a first aspect, the present invention provides a method for measuring local area atmospheric turbulence based on laser wavefront arrival angle fluctuation, the method comprising the steps of:
Step 1, laser array setting: light from a single laser source is split into multiple paths by a fiber optic beam splitter to form an array of laser beams having different base lengths (B).
Step2, receiving and measuring device: a high-resolution imaging telescope with the caliber of 20cm-30cm and the focal ratio of more than F/8 and a high-speed CMOS acquisition camera with the reading frame rate of more than 60 frames/second are adopted as a receiving device to capture laser spot images after passing through the atmospheric turbulence.
Step 3, data processing and analysis: by measuring the deviation of the laser spot centers on different base lines and calculating the covariance of the arrival angles of the laser wave fronts with different base line lengths, profile data of the atmospheric turbulence can be obtained in real time.
Step 4, calculating turbulence characteristics: the intensity and height distribution of the atmospheric turbulence are deduced based on the fluctuation variance and covariance of the arrival angle of the laser wavefront.
As a further scheme of the invention, a single laser source generates a plurality of laser beams distributed in an optical fiber array through an optical fiber beam splitter, each laser beam is led out through an independent optical fiber and is directionally emitted to the atmosphere of a local area to be measured through an adapter, and each laser beam passes through the atmosphere and then forms a light spot at a receiving end to record fluctuation information of a wave front arrival angle.
As a further scheme of the invention, the receiving device is arranged at a preset receiving position, laser spot images passing through atmospheric turbulence are continuously collected through a high-resolution imaging telescope and a high-speed CMOS camera, the phenomena of flickering and drifting of the spots are recorded, and fluctuation data of a wave front arrival angle are obtained.
As a further scheme of the invention, the receiving device also comprises a telescope with the caliber of 20cm-30cm for receiving laser spots scattered at different positions.
As a further scheme of the invention, the collected light spot images are processed by using a cross-correlation algorithm and a weighted gravity center method, and the central position of each light spot is calculated to obtain fluctuation information of the wave front arrival angle.
As a further scheme of the invention, the Kalman filtering is adopted to carry out smoothing processing on the time series data of the central position of the focal spot.
As a further scheme of the invention, the von Karman turbulence model is utilized to calculate the wave front arrival angle covariance of different base line lengths, and the wave front arrival angle covariance formula is as follows:
Is the fluctuation variance of the wave front arrival angle,/> Is the diameter of the parallel laser beam, the covariance of the angle of arrival of the wavefront with the baseline length B is:
Is a Bessel function of order,/> Is the reference angle of the X-axis direction.
As a further aspect of the invention, inWhen=0, the atmosphere model has:
In the method, in the process of the invention, Is a turbulent atmosphere intensity profile,/>Is of an outer dimension. For a fixed outer scale, assuming B > > D, the differential variance of the wavefront arrival angle can be calculated using the method of differential image motion vision-based-level-monitoring (DIMM)(Variance of relative jitter in the center position of the two laser spot images) using differential processing, the effects of vibration can be avoided and sensitivity to external dimensions can be reduced. Thus, the laser beam can be used to compose different baselines B to fit and calculate local regional atmospheric turbulence intensities using a weighted least squares method. The normalized weighting parameters are:
wherein: n is the baseline number from which the data will be derived, As a weighting coefficient for each spatial covariance. /(I)Is/>Is a variance of (c). By varying the non-fixed parameters/>, of the modelAnd/>Calculation, make/>At a minimum, the atmospheric turbulence intensity at each point can be estimated.
Compared with the prior art, the local area atmospheric turbulence measuring method based on the fluctuation of the arrival angle of the laser wave front has the following beneficial effects:
1. Measurement accuracy is improved: by utilizing the high monochromaticity, high coherence and high directivity of the laser light source, the local area atmospheric turbulence measuring method based on the fluctuation of the arrival angle of the laser wave front can provide more accurate atmospheric turbulence characteristic data than the traditional measuring technology by accurately measuring the fluctuation of the arrival angle of the laser wave front and combining a high-precision data processing algorithm. Especially, when the fluctuation variance and covariance of the wave front arrival angle are calculated, the reliability of the measured data is greatly improved by utilizing the advanced statistical analysis and filtering technology.
2. Real-time, long-lasting and dynamic measurement capabilities: the invention adopts a high-speed CMOS camera and a real-time data processing algorithm, so that the method can monitor the change of atmospheric turbulence in real time and support dynamic measurement. In addition, DIMM measurement can be simulated, the anti-interference performance of the equipment is improved, and the measurement can be carried out at any time and for a long time without depending on weather.
3. Easy operation and cost effectiveness: the method reduces the complexity and cost of the system by simple laser array and optical fiber transmission technology, and is simpler, more convenient and more economical and is easy to widely apply compared with the traditional measuring method which needs a complex optical system and high equipment.
4. Flexibility and adaptability: by adjusting the base line length of the laser beams in the laser array and the installation structure, the method can flexibly adapt to the atmospheric turbulence measurement requirements of different scales, thereby being widely applied to the local regional atmospheric turbulence measurement of domes of astronomical telescopes, optical laboratories, near-stratum and the like.
In summary, the local area atmospheric turbulence measurement method based on the fluctuation of the arrival angle of the laser wave front has technical innovation, and shows various beneficial effects in practical application, thereby having important contribution to improving the efficiency and quality of scientific research and practical application.
These and other aspects of the invention will be more readily apparent from the following description of the embodiments. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the related art, a brief description of the drawings is provided below, which are intended to provide a further understanding of the present invention and constitute a part of the specification, together with the embodiments of the present invention, serve to explain the present invention and not to limit the present invention. In the drawings:
fig. 1 is a test flow chart of a local area atmospheric turbulence measurement method based on laser wavefront arrival angle fluctuation according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of a method for measuring local area atmospheric turbulence based on fluctuation of arrival angle of laser wavefront according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of covariance of an atmosphere model on different baselines in a local area atmosphere turbulence measurement method based on laser wavefront arrival angle fluctuation according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
In some of the flows described in the specification and claims of the present invention and in the foregoing figures, a plurality of operations occurring in a particular order are included, but it should be understood that the operations may be performed out of order or performed in parallel, with the order of operations such as 101, 102, etc., being merely used to distinguish between the various operations, the order of the operations themselves not representing any order of execution. In addition, the flows may include more or fewer operations, and the operations may be performed sequentially or in parallel. It should be noted that, the descriptions of "first" and "second" herein are used to distinguish different messages, devices, modules, etc., and do not represent a sequence, and are not limited to the "first" and the "second" being different types.
Technical solutions in exemplary embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in exemplary embodiments of the present invention, and it is apparent that the described exemplary embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.
Due to the influence of atmospheric turbulence, the receiving light spot can flash and drift (distortion caused by fluctuation of the arrival angle of the laser wave front) after laser passes through a turbulence medium, and the invention aims to provide a local area atmospheric turbulence measuring method based on the fluctuation of the arrival angle of the laser wave front, which can measure local area atmospheric turbulence characteristics by measuring the fluctuation of the arrival angle of the wave front of the laser beam, is realized by measuring covariance of the arrival angles of the laser wave front of different baselines, and is used for measuring local atmospheric turbulence by using the fluctuation of the arrival angles of the wave fronts of parallel laser beams of different baselines. The local area atmospheric turbulence measurement technology based on the fluctuation of the arrival angle of the laser wave front can be suitable for local atmospheric turbulence measurement of different occasions, has a less complex structure, and can realize long-term stable measurement of atmospheric turbulence parameters of local areas such as astronomical domes, optical laboratories, near-stratum and the like. The invention realizes the measurement of the atmospheric turbulence parameters of the local area by utilizing the characteristics of high monochromaticity, high coherence, high directivity and the like of the laser light source, so that the invention has a series of advantages of better anti-interference and stronger adaptability and the like.
The technical scheme of the invention is further described below with reference to specific embodiments:
Referring to fig. 1 and 2, fig. 1 is a test flow chart of a local area atmospheric turbulence measurement method based on laser wavefront arrival angle fluctuation, and fig. 2 is a test schematic diagram of a local area atmospheric turbulence measurement method based on laser wavefront arrival angle fluctuation. The invention provides a local area atmospheric turbulence measuring method based on laser wave front arrival angle fluctuation, which comprises the following steps of:
Step S10, setting a laser array: light from a single laser source is split into multiple paths by a fiber optic beam splitter to form an array of laser beams having different base lengths (B).
In this step, a single laser source generates a plurality of laser beams distributed in an optical fiber array through an optical fiber beam splitter, each laser beam is led out through an independent optical fiber and is directionally emitted to the atmosphere of a local area to be measured through an adapter, and each laser beam passes through the atmosphere to form a light spot at a receiving end to record fluctuation information of a wave front arrival angle.
Step S20, the receiving and measuring device: a high-resolution imaging telescope with the caliber of 20cm-30cm and the focal ratio of more than F/8 and a high-speed CMOS acquisition camera with the reading frame rate of more than 60 frames/second are adopted as a receiving device to capture laser spot images after passing through the atmospheric turbulence.
In this step, the receiving device is arranged at a predetermined receiving position, laser spot images passing through atmospheric turbulence are continuously collected by a high-resolution imaging telescope and a high-speed CMOS camera, the flickering and drifting phenomena of the spots are recorded, and fluctuation data of the wave front arrival angle are obtained. The receiving device also comprises a telescope with the caliber of 20cm-30cm and a corresponding reflecting mirror (reflecting the laser beam to the telescope surface of the receiving device) for receiving the laser spots scattered at different positions.
Step S30, data processing and analysis: by measuring the deviation of the laser spot centers on different base lines and calculating the covariance of the arrival angles of the laser wave fronts with different base line lengths, profile data of the atmospheric turbulence can be obtained in real time.
Step S40, calculating turbulence characteristics: the intensity and height distribution of the atmospheric turbulence are deduced based on the fluctuation variance and covariance of the arrival angle of the laser wavefront.
In this embodiment, the collected light spot images are processed by using a cross-correlation algorithm and a weighted gravity center method, and the central position of each light spot is calculated to obtain the fluctuation information of the wave front arrival angle. And smoothing the time series data of the central position of the light spot by adopting Kalman filtering.
In this embodiment, due to the influence of the atmospheric turbulence, the receiving spot may flash and drift (distortion caused by fluctuation of the arrival angle of the laser wavefront) after the laser passes through the turbulent medium, and the local area atmospheric turbulence characteristics may be measured by measuring fluctuation of the arrival angle of the wavefront of the laser beam. The invention is realized by measuring covariance of arrival angles of laser wave fronts of different baselines. Calculating wave front arrival angle covariance of different base line lengths by utilizing von Karman turbulence model, wherein the wave front arrival angle covariance formula is as follows:
Is the fluctuation variance of the wave front arrival angle,/> Is the diameter of the parallel laser beam, the covariance of the angle of arrival of the wavefront with the baseline length B is:
Is a Bessel function of order,/> Is the reference angle of the X-axis direction.
Wherein, inWhen=0, the atmosphere model has:
In the method, in the process of the invention, Is a turbulent atmosphere intensity profile,/>Is of an outer dimension. For a fixed outer scale, assuming B > > D, the differential variance of the wavefront arrival angle can be calculated using the method of differential image motion vision-based-level-monitoring (DIMM)(Variance of relative jitter in the center position of the two laser spot images) using differential processing, the effects of vibration can be avoided and sensitivity to external dimensions can be reduced. Thus, the laser beam can be used to compose different baselines B to fit and calculate local regional atmospheric turbulence intensities using a weighted least squares method. The normalized weighting parameters are:
wherein: n is the baseline number from which the data will be derived, As a weighting coefficient for each spatial covariance. /(I)Is/>Is a variance of (c). By varying the non-fixed parameters/>, of the modelAnd/>Calculation, make/>At a minimum, the atmospheric turbulence intensity at each point can be estimated.
Referring to fig. 3, the covariance of the angle of arrival of the wavefront is mainly established under von Karman turbulence model (Kolmogorov spectrum based), but the covariance calculation on different baselines is also different for different atmosphere models. In the invention, in order to avoid the recontamination of laser beams at the detection end, a laser array is formed by adopting a laser source in an optical fiber conduction mode, the array is divided into 4 different baselines, and a telescope with the caliber of 20cm-30cm is also adopted by a receiver.
The alignment method of the baselines will directly affect the maximum height and vertical resolution of the resulting local atmospheric turbulence profile. After the base line is selected, a cross-correlation algorithm can be used to obtain the offset of the image spots of different base lines. The center of the laser image spot is calculated by using a weighted gravity center method, and in order to obtain real-time turbulence profile data, a Kalman filter or other filtering method is adopted to carry out weighted average on the observed image spot offset. The averaged results are substituted into the fluctuation variance of the wave front arrival angle under von Karman model to solve the turbulence profile.
According to the method for measuring the atmospheric turbulence in the local area based on the fluctuation of the arrival angle of the laser wave front, which is disclosed by the invention, by accurately measuring the fluctuation of the arrival angle of the laser wave front and combining a high-precision data processing algorithm, more accurate atmospheric turbulence characteristic data can be provided compared with the traditional measuring technology. Especially, when the fluctuation variance and covariance of the wave front arrival angle are calculated, the reliability of the measured data is greatly improved by utilizing the advanced statistical analysis and filtering technology.
The invention adopts a high-speed CMOS camera and a real-time data processing algorithm, so that the method can monitor the change of atmospheric turbulence in real time and support dynamic measurement. This is of great value for studying the transient nature of atmospheric turbulence and its effect on light transmission. The method reduces the complexity and cost of the system by simple laser array and optical fiber transmission technology, and is simpler, more convenient and more economical and is easy to widely apply compared with the traditional measuring method which needs a complex optical system and high equipment.
The method can flexibly adapt to the atmospheric turbulence measurement requirements of different scales by adjusting the base line length of the laser beams in the laser array, so that the method can be widely applied to the measurement of local regional atmospheric turbulence from local microscopic atmospheric turbulence research to the measurement of local regional atmospheric turbulence of wide area such as dome of astronomical telescope, optical laboratory, near stratum and the like. The local area atmospheric turbulence measuring method based on the fluctuation of the arrival angle of the laser wave front not only has technical innovation, but also shows various beneficial effects in practical application, and has important contribution to improving the efficiency and quality of scientific research and practical application.
The calculation method of the invention is similar to widely used star wavefront arrival angle calculation, and the measured wavefront arrival angle generates distortion and fluctuation to indirectly measure the parameters; however, the invention can conveniently set up the measurement of the atmospheric turbulence in local areas such as astronomical telescope in different places such as dome of optical laboratory by utilizing the characteristics of high coherence and high directivity of laser light source, and the like, and does not depend on weather, and in addition, the invention can obtain parameters such as the atmospheric turbulence distribution and the turbulence intensity in different local areas by different baseline array combinations.
It should be understood that although described in a certain order, the steps are not necessarily performed sequentially in the order described. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, some steps of the present embodiment may include a plurality of steps or stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of the steps or stages is not necessarily sequential, but may be performed alternately or alternately with at least a part of the steps or stages in other steps or other steps.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (8)
1. A method for measuring local area atmospheric turbulence based on laser wavefront arrival angle fluctuation, which is characterized by comprising the following steps:
Laser array setting: dividing light from a single laser source into multiple paths through a fiber optic beam splitter to form an array of laser beams having different base line lengths;
Receiving and measuring device: an imaging telescope and a CMOS acquisition camera are adopted as receiving devices to capture laser spot images after passing through atmospheric turbulence;
Data processing and analysis: the profile data of the atmospheric turbulence can be obtained in real time by measuring the deviation of the laser spot centers on different base lines and calculating the covariance of the arrival angles of the laser wave fronts with different base line lengths;
Turbulence characteristics calculation: the intensity and height distribution of the atmospheric turbulence are deduced based on the fluctuation variance and covariance of the arrival angle of the laser wavefront.
2. The method for measuring the atmospheric turbulence in the local area based on the fluctuation of the arrival angle of the laser wave front according to claim 1, wherein a single laser source is used for generating a plurality of laser beams distributed in an optical fiber array through an optical fiber beam splitter, each laser beam is led out through an independent optical fiber and is directionally emitted into the atmosphere of the local area to be measured through an adapter, and each laser beam passes through the atmosphere to form a light spot at a receiving end to record the fluctuation information of the arrival angle of the wave front.
3. The method for measuring the local area atmospheric turbulence based on the fluctuation of the arrival angle of the laser wave front according to claim 2, wherein the receiving device is arranged at a preset receiving position, laser spot images passing through the atmospheric turbulence are continuously acquired through a high-resolution imaging telescope and a high-speed CMOS camera, the flickering and drifting phenomenon of the spots is recorded, and fluctuation data of the arrival angle of the wave front is obtained.
4. A method of measuring local area atmospheric turbulence based on fluctuations in the angle of arrival of a laser wavefront as claimed in claim 3 further comprising using a telescope of 20cm-30cm caliber in the receiving means to receive the laser spots spread at different locations.
5. The method for measuring the atmospheric turbulence in the local area based on the fluctuation of the arrival angle of the laser wave front according to claim 4, wherein the method utilizes a cross-correlation algorithm and a weighted gravity center method to process the collected light spot images, calculates the central position of each light spot and obtains the fluctuation information of the arrival angle of the wave front.
6. The method for measuring the atmospheric turbulence in the local area based on the fluctuation of the arrival angle of the laser wavefront according to claim 5, wherein the time series data of the central position of the spot is smoothed by using a kalman filter.
7. The method for measuring local area atmospheric turbulence based on laser wavefront arrival angle fluctuation according to claim 6, wherein the calculation of the wavefront arrival angle covariance of different base line lengths is performed by using von Karman turbulence model, and the wavefront arrival angle covariance formula is:
Is the fluctuation variance of the wave front arrival angle,/> Is the diameter of the parallel laser beam, the covariance of the angle of arrival of the wavefront with the baseline length B is:
Is a Bessel function of order,/> Is the reference angle of the X-axis direction.
8. The method for measuring the atmospheric turbulence in the local area based on the fluctuation of the arrival angle of the laser wavefront according to claim 7, wherein, in the followingWhen=0, the atmosphere model has:
In the/> Is a turbulent atmosphere intensity profile,/>Is of an outer dimension.
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