CN116997067A - Method and device for measuring plasma phase distribution - Google Patents
Method and device for measuring plasma phase distribution Download PDFInfo
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- H05H1/0006—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature
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- H05H1/0037—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature using electromagnetic or particle radiation, e.g. interferometry by spectrometry
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- H05H1/0006—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature
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Abstract
A measuring method and a measuring device for plasma phase distribution, wherein the measuring method for plasma phase distribution comprises the following steps: the pulse laser passes through the plasma to be measured so as to deflect at least part of the pulse laser; focusing the pulse laser passing through the plasma to be tested; in the focused pulse laser, the part which is not deflected is incident on any one of the strip-shaped baffle belts of the strip-shaped filter disc, and the deflected part is filtered by the strip-shaped filter disc to obtain a plurality of beams of filtered laser; imaging a plurality of beams of filtered laser to obtain a measurement image; obtaining deflection quantity distribution of a deflected part of the focused pulse laser on the strip filter according to the strip passband position of the strip filter and the boundary of a region formed by each beam of filter laser in the measurement image; and obtaining the phase distribution of the plasma to be measured in the width direction of the strip filter according to the deflection quantity distribution and the relation between the deflection quantity distribution and the phase distribution of the plasma to be measured.
Description
Technical Field
The present invention relates to the field of measurement of plasma phase distribution, and in particular, to a method and an apparatus for measuring plasma phase distribution.
Background
The material state of the plasma (including parameters such as electron density, temperature and the like) covers a wide range and has important application in fields such as astrophysics, geology, agricultural science, precision machining, inertial confinement fusion and the like. In inertial confinement fusion, laser-plasma interactions (LPI) greatly affect energy coupling efficiency, and the occurrence threshold and gain sensitivity of LPI depend on crown plasma parameters. There are various techniques for diagnosing the electron density of the plasma in the related research, one common method is to measure the phase carried by the diagnostic light after passing through the plasma, and then make a column symmetry assumption on the phase, and obtain the electron density information of the plasma after abbe transformation. However, in many cases, since the column symmetry assumption is not satisfied, the electron density of one line integral can be given by the phase only. Therefore, measuring plasma phase is particularly critical in these situations.
As a general phase measurement method, interferometry is a method for obtaining phase information of plasma by measuring movement of interference fringes, and a related method for diagnosing the phase of plasma requires spectrum analysis of an interferogram during data processing, and the phase information of plasma is obtained by movement of fringes. However, in application scenarios where electron density gradients such as crown laser plasma are large, high density gradients can cause interference fringes to become extremely tight, which places high demands on the spatial resolution of the acquisition device. While interferometry also requires that the diagnostic laser have a strong coherence. The interferometry has strong application restrictions in the selection of diagnostic light sources and acquisition devices.
In another measurement method for obtaining the plasma phase, although an interference method is not needed, a complex algorithm is adopted in the process of reconstructing the plasma phase, and the reconstruction algorithm needs to predict the information of the plasma in advance, and the plasma phase can be obtained by carrying out complex fitting on multiple parameters in the information of the plasma.
Disclosure of Invention
In view of the above, the present invention provides a method and apparatus for measuring a plasma phase distribution, so as to solve at least one of the above problems.
As a first aspect of the present invention, there is provided a method of measuring a plasma phase distribution, comprising:
the pulse laser passes through the plasma to be detected so as to deflect at least part of the pulse laser, and the pulse laser passing through the plasma to be detected carries phase distribution information of the plasma to be detected;
focusing the pulse laser passing through the plasma to be tested; in the focused pulse laser, the part which is not deflected is incident on any one of the strip-shaped baffle belts of the strip-shaped filter disc, and the deflected part is filtered by the strip-shaped filter disc to obtain a plurality of beams of filtered laser; the strip-shaped filter discs are distributed with a plurality of strip-shaped pass bands along the width direction, and the deflection amounts of pulse lasers passing through different strip-shaped pass bands are different;
imaging a plurality of beams of filtered laser to obtain a measurement image;
obtaining deflection quantity distribution of a deflected part of the focused pulse laser on the strip filter according to the strip passband position of the strip filter and the boundary of a region formed by each beam of filter laser in the measurement image;
and obtaining the phase distribution of the plasma to be measured in the width direction of the strip filter according to the deflection quantity distribution and the relation between the deflection quantity distribution and the phase distribution of the plasma to be measured.
According to an embodiment of the present invention, measuring a boundary of an area formed by each of the filtered lasers in the image according to a position of a passband of the filter strip to obtain a deflection amount distribution of a portion of the focused pulse laser, the portion being deflected on the filter strip, includes:
obtaining deflection quantity of the filter laser at each boundary according to the position of the strip passband of the strip filter and the boundary of the region formed by each beam of filter laser in the measured image;
and obtaining deflection quantity distribution of the deflected part on the strip filter in the focused pulse laser according to the deflection quantity of the filter laser at each boundary.
According to an embodiment of the present invention, obtaining a deflection amount distribution of a portion of the focused pulse laser, which is deflected, on the strip filter according to a deflection amount of the filtered laser at each boundary includes:
and carrying out interpolation fitting on the deflection quantity of the filter laser at each boundary to obtain deflection quantity distribution of the deflected part on the strip filter sheet in the focused pulse laser.
According to an embodiment of the present invention, the relationship between the deflection amount distribution and the phase distribution of the plasma to be measured includes:
wherein ,dthe deflection amount distribution is represented by the distribution of deflection amounts,f 1 represents the focal length at which the pulsed laser light passing through the plasma to be measured is focused,indicating the wavelength of the pulsed laser, +.>Indicating the phase distribution of the plasma to be measured,xthe direction of the axis is along the length of the strip filter,ythe direction of the axis is along the width direction of the strip filter.
According to an embodiment of the present invention, a method for determining a boundary of an area formed by each of filter lasers in a measurement image includes:
the area of the measurement image including the filtered laser light is assigned a first value and the area not including the filtered laser light is assigned a second value to determine the boundary of the area formed by each of the filtered laser light in the measurement image.
According to an embodiment of the invention, the spot size of the pulsed laser is larger than the size of the plasma to be measured.
According to an embodiment of the present invention, the incidence of the unbiased portion on any one of the strip-shaped barriers of the strip-shaped filter includes:
the part which is not deflected is incident to the geometric center of any one strip-shaped baffle band of the strip-shaped filter disc.
As a second aspect of the present invention, there is also provided a measuring apparatus for plasma phase distribution for realizing the above-described measuring method, the measuring apparatus comprising:
the pulse light source is suitable for emitting pulse laser, wherein the pulse laser passes through the plasma to be detected so as to deflect at least part of the pulse laser, and the pulse laser passing through the plasma to be detected carries phase distribution information of the plasma to be detected;
a first lens adapted to focus a pulse laser light to be passed through the plasma to be measured;
the strip-shaped filter disc comprises a plurality of strip-shaped baffle bands and a plurality of strip-shaped pass bands which are distributed along the width direction, wherein the strip-shaped baffle bands and the strip-shaped pass bands are alternately arranged, a part which is not deflected in the focused pulse laser is incident on any strip-shaped baffle band of the strip-shaped filter disc, and the deflected part is filtered through the strip-shaped filter disc to obtain a plurality of beams of filtered laser;
the second lens is suitable for imaging the multiple beams of filtered laser to obtain a measurement image;
the acquisition device is suitable for acquiring a measurement image formed by the second lens;
the computing equipment is suitable for obtaining the phase distribution of the plasma to be tested in the width direction of the strip filter according to the measurement image and the strip passband position of the strip filter.
According to an embodiment of the invention, a strip filter is disposed at the focal plane of the first lens.
According to the embodiment of the invention, the deflection quantity distribution of the deflected pulse laser on the strip filter sheet can be obtained according to the strip passband position of the strip filter sheet and the boundary of the area formed by each beam of filter laser in the measurement image, and the phase distribution of the plasma to be measured in the width direction can be obtained according to the relationship between the deflection quantity distribution and the phase distribution of the plasma to be measured.
According to the embodiment of the invention, the stripe density in the obtained measurement image is lower than the interference stripe density in the interference method by utilizing the strip filter, the requirement on the spatial resolution of the acquisition equipment is lower, and the measuring method of the ion bulk phase distribution provided by the embodiment of the invention has higher precision.
Drawings
Fig. 1 shows a flowchart of a method for measuring a plasma phase distribution according to an embodiment of the present invention;
fig. 2 shows a schematic diagram of a measurement device for phase distribution of a plasma to be measured according to an embodiment of the present invention;
FIG. 3 shows a phase distribution of a plasma to be measured provided in accordance with an embodiment of the present invention;
FIG. 4 illustrates a front view of a strip filter provided in accordance with a specific embodiment of the present invention;
FIG. 5 illustrates a binarized image provided in accordance with certain embodiments of the present invention;
fig. 6 shows the data at x=0 in fig. 6;
FIG. 7 shows the result of assigning the values of FIG. 6;
FIG. 8 shows the results after fitting to FIG. 7;
FIG. 9A illustrates a phase distribution of a plasma calculated according to a method in a particular embodiment;
FIG. 9B illustrates absolute errors of a phase distribution of a plasma calculated according to a method in a particular embodiment;
FIG. 10A shows a background interferogram obtained by interferometry according to an embodiment of the present invention;
fig. 10B shows a plasma interference pattern provided in accordance with an embodiment of the present invention.
Description of the reference numerals
1 pulse light source
2 first lens
3 strip filter disc
4 second lens
5 acquisition equipment
6 plasma to be measured
Detailed Description
The present invention will be further described in detail below with reference to specific embodiments and with reference to the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent.
Fig. 1 shows a flowchart of a method for measuring a plasma phase distribution according to an embodiment of the present invention.
As shown in FIG. 1, the method for measuring the plasma phase distribution includes operations S1 to S5.
In operation S1, the pulse laser passes through the plasma to be measured, so that at least part of the pulse laser deflects, and the pulse laser passing through the plasma to be measured carries the phase distribution information of the plasma to be measured.
Focusing the pulse laser passing through the plasma to be measured in operation S2; in the focused pulse laser, the part which is not deflected is incident on any one of the strip-shaped baffle belts of the strip-shaped filter disc, and the deflected part is filtered by the strip-shaped filter disc to obtain a plurality of beams of filtered laser; the strip-shaped filter discs are distributed with a plurality of strip-shaped pass bands along the width direction, and the deflection amounts of pulse lasers passing through different strip-shaped pass bands are different.
In operation S3, a plurality of filtered lasers are imaged to obtain a measurement image.
In operation S4, the deflection amount distribution of the deflected portion of the focused pulse laser on the strip filter is obtained from the position of the strip pass band of the strip filter and the boundary of the region formed by each of the filtered lasers in the measurement image.
In operation S5, a phase distribution of the plasma to be measured in the width direction of the strip filter is obtained according to the deviation amount distribution, the relationship between the deviation amount distribution and the phase distribution of the plasma to be measured.
According to the embodiment of the invention, the deflection quantity distribution of the deflected pulse laser on the strip filter sheet can be obtained according to the strip passband position of the strip filter sheet and the boundary of the area formed by each beam of filter laser in the measurement image, and the phase distribution of the plasma to be measured in the width direction can be obtained according to the relationship between the deflection quantity distribution and the phase distribution of the plasma to be measured.
According to the embodiment of the invention, the stripe density in the obtained measurement image is larger than the interval of interference stripes in the interference method by utilizing the strip filter, the stripe density in the obtained measurement image is lower than the density of the interference stripes in the interference method by utilizing the strip filter, the requirement on the spatial resolution of the acquisition equipment is lower, and the measuring method of the ion phase distribution provided by the embodiment of the invention has higher precision.
According to an embodiment of the present invention, in the pulse laser passing through the plasma to be measured, a portion incident to the plasma to be measured is deflected and a portion not incident to the plasma to be measured is not deflected in operation S1.
According to an embodiment of the present invention, in operation S4, obtaining a deflection amount distribution of a portion of the focused pulse laser, which is deflected, on the strip filter according to a position of a strip pass band of the strip filter and a boundary of a region formed by each of the filtered lasers in the measurement image, includes: obtaining deflection quantity of the filter laser at each boundary according to the position of the strip passband of the strip filter and the boundary of the region formed by each beam of filter laser in the measured image; and obtaining deflection quantity distribution of the deflected part on the strip filter in the focused pulse laser according to the deflection quantity of the filter laser at each boundary.
According to an embodiment of the present invention, obtaining a deflection amount distribution of a portion of the focused pulse laser, which is deflected, on the strip filter according to a deflection amount of the filtered laser at each boundary includes: and performing difference fitting on the deflection quantity of the filtered laser at each boundary to obtain deflection quantity distribution of the deflected part on the strip filter sheet in the focused pulse laser.
According to an embodiment of the present invention, the relationship between the deflection amount distribution of the pulse laser and the phase distribution of the plasma to be measured includes:
wherein ,dthe deflection amount distribution of the pulse laser is shown,f 1 represents the focal length at which the pulsed laser light passing through the plasma to be measured is focused,indicating the wavelength of the pulsed laser, +.>Indicating the phase distribution of the plasma to be measured,xthe direction of the axis is along the length of the strip filter,ythe direction of the axis is along the width direction of the strip filter.
According to an embodiment of the present invention, a method for determining a boundary of an area formed by each of filter lasers in a measurement image includes: the method includes assigning a first value to a region in the measurement image that includes the filtered laser light and a second value to a region in the measurement image that does not include the filtered laser light to determine a boundary of a region formed by each of the filtered laser light in the measurement image to determine a boundary of a region formed by each of the filtered laser light in the plurality of filtered laser light images. For example, by using the binarization method, the area having the filtered laser light is assigned 1, and the area having no filtered laser light is assigned 0.
According to the embodiment of the invention, the spot size of the laser beam is larger than the size of the plasma to be detected, so that the information of the complete phase distribution of the plasma to be detected is obtained.
According to an embodiment of the present invention, the incidence of the unbiased portion on any one of the strip-shaped barriers of the strip-shaped filter includes: the part which is not deflected is incident to the geometric center of any one strip-shaped baffle band of the strip-shaped filter disc.
Fig. 2 shows a schematic diagram of a measurement device for phase distribution of a plasma to be measured according to an embodiment of the present invention.
As shown in fig. 2, the measuring apparatus includes: a pulsed light source 1, a first lens 2, a strip filter 3, a second lens 4, an acquisition device 5 and a computing device (not shown in the figures).
The pulse light source 1 is adapted to emit a pulse laser, the pulse laser passes through the plasma 6 to be measured, so that at least part of the pulse laser deflects, and the pulse laser passing through the plasma 6 to be measured carries phase distribution information of the plasma 6 to be measured. The first lens 2 is adapted to focus the pulsed laser light passing through the plasma to be measured. The strip filter 3 includes a plurality of strip-shaped blocking bands and a plurality of strip-shaped pass bands distributed in the width direction, wherein the strip-shaped blocking bands and the strip-shaped pass bands are alternately arranged. In the focused pulse laser, the part which is not deflected is incident on any one of the strip-shaped baffle belts of the strip-shaped filter disc 3, and the deflected part is filtered by the strip-shaped filter disc 3 to obtain a plurality of filtered lasers. The strip filter 3 distributes a plurality of strip pass bands along the width direction, and the deflection amounts of pulse lasers passing through different strip pass bands are different.
The second lens 4 is adapted to image the plurality of filtered lasers to obtain a measurement image. The acquisition device 5 is adapted to acquire a measurement image of the second lens. The computing device is suitable for obtaining the phase distribution of the plasma to be measured in the width direction of the strip filter 3 according to the measured image.
According to an embodiment of the invention, a strip filter 3 is arranged at the focal plane of the first lens 2.
A detailed description of how to perform plasma phase distribution measurements using the measuring apparatus of the present invention is provided below with reference to fig. 2 by way of an exemplary embodiment.
A pulse laser beam generated by the pulse light source 1 passes through the plasma 6 to be measured, and the phase distribution of the plasma 6 to be measured is shown in fig. 3, in the pulse laser beam, the part of the pulse laser beam which is incident to the plasma 6 to be measured deflects, and the part which is not incident to the plasma 6 to be measured propagates along a straight line, so that the deflection does not occur. The pulse light source 1 is connected with a plasma 6 to be measured in a light path. The laser wavelength generated by the pulsed light source 1 may be 263nm, for example.
The first lens 2, the strip filter 3 and the second lens 4 form a strip filter unit, the focal length of the first lens 2 and the second lens 4 is 50cm, the strip filter unit has two functions, the first function is to image the plasma 6 to be detected to the acquisition equipment 5, and the second function is to filter pulse laser carrying plasma information and passing through the plasma to be detected based on the strip filter 3. Specifically, the first lens 2 is used for focusing the pulse laser passing through the plasma 6 to be measured, the strip filter 3 is placed at the fourier plane of the first lens 2 and used for filtering the part of the focused pulse laser, which is not deflected, and the second lens 4 is used for receiving the filtered pulse laser and imaging the filtered pulse laser at the acquisition device 5. The plasma 6 to be measured, the first lens 2, the strip filter 3 and the second lens 4 are sequentially connected with the acquisition equipment 5 in an optical path.
Fig. 4 illustrates a front view of a filter strip provided in accordance with a specific embodiment of the present invention.
As shown in fig. 4, the strip filter 3 is composed of a series of strip-shaped blocking bands and strip-shaped pass bands, wherein one strip-shaped pass band is arranged between two strip-shaped blocking bands, and one strip-shaped blocking band is arranged between any two strip-shaped pass bands. The strip filter 3 is disposed in the vertical direction. The strip-shaped blocking band is a 0-level strip-shaped blocking band, a 1-level strip-shaped passband, a 1-level strip-shaped blocking band and a 2-level strip-shaped passband … from bottom to top. The filtering process is as follows: in the focused pulse laser, the strip-shaped blocking band shields the pulse laser beam with corresponding deflection, and the strip-shaped passband allows the pulse laser beam with corresponding deflection to pass through. In the focused pulse laser, the part which is not deflected is incident to the geometric center of the 0-level baffle band of the strip filter. The amounts of deflection of the pulse laser light passing through the different strip pass bands of the strip filter 3 are different. The lengthwise direction of the strip filter 3 is along the x-axis direction, and the widthwise direction of the strip filter 3 is along the y-axis direction. In this embodiment, the width of the zero-order strip of the strip filter 3 is 0.5mm, and the width of the remaining strip pass band and strip stop is 0.3mm. The width of the strip-shaped passband and the strip-shaped passband have no fixed value, and the lengths of the strip-shaped passband and the strip-shaped passband should generally be set to be consistent with the optical element used, for example, for a 2 inch lens, the lengths of the strip-shaped passband and the strip-shaped passband should be 2 inches, i.e., about 5cm.
The second lens 4 images the plurality of filtered lasers passing through the strip filter 3 to obtain a measurement image, and the acquisition device 5 acquires the measurement image formed by the second lens 4.
The computing equipment is suitable for obtaining the phase distribution of the plasma to be measured in the width direction of the strip-shaped filter disc according to the measured image and the strip-shaped passband position of the strip-shaped filter disc, and particularly, the computing equipment is used for sequentially carrying out binarization processing on the measured image, carrying out region assignment on the image after the binarization processing by combining the strip-shaped passband position of the strip-shaped filter disc, and carrying out data fitting and phase reconstruction. For ease of understanding, the detailed procedures of binarization processing, region assignment, data fitting and phase reconstruction are described below using steps a-D.
Step A: the binarization process is specifically performed as follows.
The area with the filtered laser light in the measurement image is assigned 1, and the area without the filtered laser light is assigned 0. The binarized image is shown in fig. 5.
And (B) step (B): the specific procedure of region assignment is as follows.
The region is assigned to the binarized image, and the two images are different on the same boundaryxThe deflection amounts of the pulse lasers corresponding to the values are the same, and for convenience of explanation, the embodiment selects the images after binarizationxThe corresponding plasma phase at=0 was measured. For a pair ofxThe corresponding plasma phase at=0 is measured first for fig. 5xData at=0 were extracted.
Fig. 6 shows the data at x=0 in fig. 5.
As shown in fig. 6, the plurality of bands are included in fig. 6, each band corresponds to one of the bar pass bands, and the bar located at the far right side in fig. 6 corresponds to the level 1 pass band, that is, the bar with the largest y-axis coordinate in fig. 6 corresponds to the level 1 pass band. The bars in fig. 6 correspond to the pass bands of level 1, level 2, and level 3 … in this order from right to left, and the minimum and maximum values of the coordinates on the y-axis represent two boundaries (horizontal boundaries) extending in the horizontal direction for the corresponding bar pass band, respectively, for each of the bars in fig. 6. Taking the rightmost band in fig. 6 as an example (corresponding to the level 1 passband), the minimum of the y-axis coordinates corresponds to the upper boundary in the level 1 passband and the maximum of the y-axis coordinates corresponds to the lower boundary in the level 1 passband. The positions of the strip pass bands of the strip filter 3 are shown in FIG. 5, i.e. the distance between the two boundaries of each strip pass band extending in the horizontal direction and the center of the 0-class strip stop bandThe band is assigned, and the assigned value of each boundary is the deflection of the pulse laser at the boundary. Since, for example, the boundary of the level 1 bar-shaped passband is 0.25mm and 0.55mm from the center of the level 0 bar-shaped passband, the two boundaries from bottom to top in fig. 5 are assigned 0.25mm and 0.55mm, respectively, since the boundaries are different on the same boundaryxThe deflection amounts of the corresponding pulse lasers at the values are the same, so that the pulse lasers are different on the same boundaryxThe assigned values are the same at the values. It can be seen that the value assigned to the minimum value of the y-axis coordinate is 0.55, the value assigned to the maximum value of the y-axis coordinate is 0.25, and so on in the rightmost band in fig. 6.
Fig. 7 shows the result after assignment to fig. 6.
As shown in fig. 7, the result of the assignment is the amount of deflection of the beam of the pulsed laser at the horizontal boundaries of the respective bar pass bands. For example, in the rightmost stripe in fig. 6, the assigned value at the minimum value of the y-axis coordinate is 0.55, the assigned value at the maximum value of the y-axis coordinate is 0.25, that is, the deflection amount of the pulse laser at the lower boundary is 0.25, and the deflection amount of the pulse laser at the upper boundary is 0.55, corresponding to the level 1 passband.
Step C: the data fitting procedure is as follows.
Interpolation fitting is performed on the results of fig. 7 to obtain fig. 8.
Fig. 8 shows the results after fitting to fig. 7.
As shown in fig. 8, the data obtained after fitting is actually the deflection amount distribution d of the beam of the pulse laser on the strip filter.
Step D: the phase reconstruction process is as follows.
Obtaining the phase distribution of the plasma according to the relationship between the deflection quantity distribution of the pulse laser and the phase distribution of the plasma to be measuredφ(x，y)。
Fig. 9A shows a phase distribution of plasma calculated according to a method in a particular embodiment.
Fig. 9B shows the absolute error of the phase distribution of the plasma calculated according to the method in the specific embodiment.
As shown in fig. 9A-9B, the method for measuring the phase distribution of the plasma (the method for reconstructing the quantitative schlieren of the phase of the plasma) provided by the embodiment of the invention has small error in a high-density region, the absolute error is about 0.8 radian (the unit of the phase of the plasma is radian), the relative error is about 1%, and the error meets the requirement for measuring the phase distribution of the plasma and also meets the diagnostic requirement for the electron density of the plasma.
In the method for acquiring the plasma phase distribution in the embodiment of the invention, the strip filter 3 is adopted, so that the fringe spacing of the image formed by the obtained multiple beams of filtered laser is wider (see fig. 5), and compared with the method for processing interference fringes with narrower spacing in an interferometry, the method reduces the requirement on the spatial resolution of the acquisition equipment 5. The advantages of the measurement method provided by the embodiment of the present invention will be described herein with specific data. First, the interference fringes produced by the interferometry are simulated. For the same plasma phase distribution as in the specific embodiment of the present invention, the laser wavelength in the interferometry is 263nm, the interference angle is 0.2 degrees, the simulated background interference pattern is shown in fig. 10A, the plasma interference is shown in fig. 10B, and it can be seen that although the interference angle is smaller in the interferometry and the fringe spacing in the background interference pattern is wider, after the plasma is introduced, interference fringes in the plasma area are crowded and the fringe density becomes larger. This is due to the high density fringes created by the large plasma phase gradient. Comparing fig. 3 with fig. 10A and fig. 10B, it can be seen that the fringe density in the embodiment of the present invention is lower than that in the interferometry, and the phase measurement method proposed in the embodiment of the present invention has lower requirements on the spatial resolution of the acquisition device 5.
According to the embodiment of the invention, compared with the current system applied to plasma phase measurement, the information of the plasma needs to be predicted in advance, and the phase of the plasma can be acquired by performing complex fitting on multiple parameters. According to the measuring method provided by the embodiment of the invention, an equation is not required to be used for representing the electron density of the plasma, the reconstruction of the plasma phase can be realized by using only the parameters of the light path, and a new method is provided for the phase measurement of the plasma.
While the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be understood that the invention is not limited to the details of construction and the embodiments described, but is capable of modification in various other respects, all without departing from the spirit and principles of the present invention.
Claims (9)
1. A method for measuring a plasma phase distribution, comprising:
the pulse laser passes through the plasma to be detected so as to deflect at least part of the pulse laser, and the pulse laser passing through the plasma to be detected carries phase distribution information of the plasma to be detected;
focusing the pulse laser passing through the plasma to be detected; in the focused pulse laser, the part which is not deflected is incident on any one of the strip-shaped baffle belts of the strip-shaped filter disc, and the deflected part is filtered by the strip-shaped filter disc to obtain a plurality of beams of filtered laser; the strip-shaped filter discs are distributed with a plurality of strip-shaped pass bands along the width direction, and the deflection amounts of pulse lasers passing through different strip-shaped pass bands are different;
imaging the multiple beams of filtered laser to obtain a measurement image;
obtaining deflection quantity distribution of a deflected part on the strip filter in the focused pulse laser according to the strip passband position of the strip filter and the boundary of the area formed by each beam of filter laser in the measurement image;
and obtaining the phase distribution of the plasma to be measured in the width direction of the strip filter according to the deflection quantity distribution and the relation between the deflection quantity distribution and the phase distribution of the plasma to be measured.
2. The measurement method according to claim 1, wherein obtaining a deflection amount distribution of a portion of the focused pulse laser light, on which deflection occurs, on the strip filter based on a strip pass band position of the strip filter, a boundary of a region formed by each of the filter lasers in the measurement image, comprises:
obtaining deflection quantity of the filter laser at each boundary according to the position of the strip passband of the strip filter and the boundary of the region formed by each beam of filter laser in the measurement image;
and obtaining deflection quantity distribution of the deflected part on the strip-shaped filter disc in the focused pulse laser according to the deflection quantity of the filter laser at each boundary.
3. The measurement method according to claim 2, wherein obtaining a deflection amount distribution of the deflected portion of the focused pulse laser light on the strip filter from the deflection amount of the filtered laser light at each boundary comprises:
and carrying out interpolation fitting on the deflection quantity of the filter laser at each boundary to obtain deflection quantity distribution of the deflected part on the strip filter sheet in the focused pulse laser.
4. The method of claim 1, wherein the relationship between the deflection amount distribution and the phase distribution of the plasma to be measured comprises:
；
wherein ,drepresenting the deflection amount distribution in question,f 1 represents the focal length at which the pulsed laser light passing through the plasma to be measured is focused,representing the wavelength of said pulsed laser, +.>Representing the phase distribution of the plasma to be measured,xthe direction of the axis is along the length of the strip filter,ythe direction of the shaft is along the width direction of the strip filter sheet。
5. The method of measuring according to claim 2, wherein the method of determining the boundary of each of the areas formed by the filtered laser light in the measurement image includes:
and assigning a first value to a region including the filtered laser in the measurement image and a second value to a region not including the filtered laser, so as to determine the boundary of the region formed by each beam of the filtered laser in the measurement image.
6. The method of claim 1, wherein the pulsed laser has a spot size that is larger than the size of the plasma to be measured.
7. The method of measuring of claim 1, wherein the portion of the strip that is not deflected is incident on any one of the strip-shaped barriers of the strip-shaped filter sheet comprising:
the part which is not deflected is incident to the geometric center of any one strip-shaped baffle band of the strip-shaped filter disc.
8. A measurement device for plasma phase distribution for implementing the measurement method of any one of claims 1-7, the measurement device comprising:
the pulse light source is suitable for emitting pulse laser, wherein the pulse laser passes through the plasma to be detected so as to deflect at least part of the pulse laser, and the pulse laser passing through the plasma to be detected carries phase distribution information of the plasma to be detected;
the first lens is suitable for focusing the pulse laser passing through the plasma to be detected;
the strip-shaped filter disc comprises a plurality of strip-shaped baffle bands and a plurality of strip-shaped pass bands which are distributed along the width direction, wherein the strip-shaped baffle bands and the strip-shaped pass bands are alternately arranged, and in the focused pulse laser, a part which is not deflected is incident on any strip-shaped baffle band of the strip-shaped filter disc, and the deflected part is filtered through the strip-shaped filter disc to obtain a plurality of beams of filtered laser;
the second lens is suitable for imaging the plurality of filtered lasers to obtain a measurement image;
the acquisition equipment is suitable for acquiring a measurement image formed by the second lens;
and the computing equipment is suitable for obtaining the phase distribution of the plasma to be detected in the width direction of the strip filter according to the measurement image and the strip passband position of the strip filter.
9. The measurement device of claim 8, wherein the strip filter is disposed at a focal plane of the first lens.
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