Multi-line imaging velocity interferometer and shock wave velocity measurement method based on this interferometer

Abstract

The present invention provides a multi-line imaging velocity interferometer and a shock wave velocity measurement method based on the interferometer, which solves the problem that the existing laser fusion spherical fuel compression symmetry diagnosis cannot accurately infer the space-time process of fuel compression. The interferometer includes a laser source, a probe coupling mirror, a probe beam splitter, a front-end lens, a signal beam splitter, and two heterodyne interference optical path units; the laser emitted by the laser source is focused on the surface to be measured through the probe coupling mirror, the probe beam splitter, and the front-end lens, and the signal reflected by the surface to be measured enters the signal beam splitter through the front-end lens and the probe beam splitter, is divided into two beams and enters the two heterodyne interference optical path units respectively; each heterodyne interference optical path unit includes an interferometer pre-mirror, a multi-line beam splitter group, a first heterodyne interference component, a streak camera, and N-1 second heterodyne interference components; the signal light is divided into N branches by the multi-line beam splitter group; the N branches are respectively imaged on the streak camera through the first heterodyne interference component and the N-1 second heterodyne interference components.

Description

Technical Field

[0001] The present invention belongs to the field of laser fusion, and relates to a multi-line imaging type velocity interferometer and a shock wave velocity laser Doppler heterodyne interference measurement method based on the multi-line imaging type velocity interferometer. Background Technique

[0002] With the continuous in-depth research on inertial confinement fusion (ICF), people have found that the conditions for achieving high-gain fusion are extremely harsh because the fusion fuel must reach extremely high temperatures and pressures. However, the compression of the fuel is not carried out in a high-pressure container, and no physical container can withstand extremely high temperatures and pressures; it is achieved by irradiating a spherical deuterium-tritium gas fuel (pellet) from all directions with high-energy lasers or particle beams, and using the reaction force of the irradiation to compress the internal fuel. The compression spherical symmetry is crucial for achieving fusion. If it is asymmetric, the fuel sphere will rupture in advance, unable to reach extremely high temperatures and pressures, and the fusion will fail. Therefore, the compression symmetry has become one of the important assessment contents in ICF research. At present, for the diagnosis of the compression symmetry of the laser fusion spherical fuel, the "Velocity Interferometer System for Any Reflecotor (VISAR)" based on the laser Doppler heterodyne interferometry velocity measurement technology is usually adopted. By measuring the velocity change process of the inward compression of the fuel sphere surface, the fuel compression process can be understood and the compression symmetry of the fuel can be judged. However, the "line imaging velocity interferometer" cannot obtain two-dimensional image information because the compression process of the fusion fuel is extremely fast (in the ns order of magnitude), and there is no such fast high-speed camera available to record the two-dimensional information of the fuel surface; usually, a streak camera is used to perform a high-time-resolution scan on the compression process of a line on the fuel surface. The information on a very short line on the fuel sphere surface is too little for judging the compression symmetry of the entire spherical fuel.

[0003] For this reason, researchers have proposed a two-dimensional imaging type velocity interferometer (2D VISAR). Compared with the "line imaging velocity interferometer", the "2D VISAR" uses a conventional camera and can obtain a frame of two-dimensional image of a local spherical crown of the fuel at a certain moment through time control. However, compared with a compression process, the information volume of a single frame of image is still too small, and it is still impossible to accurately infer the spatio-temporal process of fuel compression.

[0004] In addition to 2D VISAR, researchers have also proposed the concepts of "biaxial VISAR" and "multi-axial VISAR". The essence of both is to set up single-sided or multi-sided mirrors inside a fuel sphere with a diameter of several hundred micrometers, facing different directions of the sphere, and establish multiple micro-velocity measurement optical paths, in order to select a straight line from different azimuths of the fuel sphere and obtain its velocity history information. Although this method can measure "two" or "multiple" spherical cap regions simultaneously under the premise of only measuring one straight line, it is very difficult to arrange mirrors inside a fuel sphere with a diameter of several hundred micrometers, and the mirrors are located inside the gaseous fuel sphere, seriously disrupting the fuel compression process, restricting the fuel compression ratio, and unable to achieve extreme high-temperature and high-pressure fusion conditions.

[0005] From the above technical content, it can be seen that currently in the diagnosis of the compression symmetry of laser fusion spherical fuels, whether it is "uniaxial" or "multi-axial" VISAR, it can only obtain a straight line on the spherical cap region or a single-frame two-dimensional image at a certain moment for measurement. For judging the compression symmetry of the fuel sphere, the amount of information obtained is too small, so the temporal and spatial process of fuel compression cannot be accurately inferred. Summary of the Invention

[0006] In order to solve the technical problem that in the existing diagnosis of the compression symmetry of laser fusion spherical fuels, only a straight line on the spherical cap region or a single-frame two-dimensional image at a certain moment can be obtained for measurement, and the temporal and spatial process of fuel compression cannot be accurately inferred, the present invention provides a multi-line imaging type velocity interferometer and a shock wave velocity measurement method based on this interferometer.

[0007] To achieve the above object, the technical solution provided by the present invention is:

[0008] A multi-line imaging type velocity interferometer, characterized in that: it includes an imaging unit and two heterodyne interference optical path units;

[0009] The imaging unit includes a laser source, a probe coupling mirror, a probe beam splitter, a front-end lens, and a signal beam splitter; the probe laser emitted by the laser source is transmitted through the probe coupling mirror, reflected by the probe beam splitter, and transmitted through the front-end lens in sequence, and then focused on the object surface to be measured to form a Doppler signal. The Doppler signal reflected by the object surface to be measured is transmitted through the front-end lens and the probe beam splitter in sequence, and then enters the signal beam splitter, and is split into two beams of Doppler signal light by the signal beam splitter;

[0010] The two heterodyne interference optical path units are respectively located on the two beams of Doppler signal light emitted by the signal beam splitter;

[0011] Each beat-frequency interference optical path unit includes an interferometer pre-mirror, a multi-line beam splitter group, a first beat-frequency interference component, a second beat-frequency interference component, and a streak camera; the Doppler signal light is transmitted through the interferometer pre-mirror and then incident on the multi-line beam splitter group, and is divided into N branches by the multi-line beam splitter group, where N is an integer greater than or equal to 2; there are N - 1 second beat-frequency interference components;

[0012] One of the branches passes through the first beat-frequency interference component and is imaged on the streak camera, and the remaining branches respectively pass through N - 1 second beat-frequency interference components and are imaged on the streak camera;

[0013] The first beat-frequency interference component includes an interferometer one and a first imaging mirror in front of the streak camera arranged in sequence along the optical path;

[0014] The second beat-frequency interference component includes an interferometer two, a Dove prism, a mirror group, and a second imaging mirror in front of the streak camera arranged in sequence along the optical path. By rotating the Dove prism, the direction of the interference image imaged on the streak camera is changed, and by swinging the mirror group, the position of the interference image imaged on the streak camera is changed, so that the interference images of the first beat-frequency interference component and the second beat-frequency interference component are arranged in a "one" shape along the slit direction of the streak camera.

[0015] Further, the multi-line beam splitter group includes 1 multi-line beam splitter and 1 mirror arranged side by side;

[0016] The multi-line beam splitter is located on the outgoing optical path of the interferometer pre-mirror, and the first beat-frequency interference component is located on the transmitted optical path of the multi-line beam splitter;

[0017] The mirror is located on the reflected optical path of the multi-line beam splitter, and the second beat-frequency interference component is located on the outgoing optical path of the mirror.

[0018] Further, the multi-line beam splitter group includes m multi-line beam splitters and 1 mirror arranged side by side, where m = N - 1 and N is an integer greater than or equal to 3;

[0019] The m multi-line beam splitters are respectively the first multi-line beam splitter, the second multi-line beam splitter, ……, the m-th multi-line beam splitter;

[0020] The first multi-line beam splitter is located on the outgoing optical path of the interferometer pre-mirror, and the first beat-frequency interference component is located on the transmitted optical path of the first multi-line beam splitter;

[0021] The mirror is located on the transmitted optical path of the m-th multi-line beam splitter;

[0022] The N - 1 second beat-frequency interference components are respectively located on the reflected optical paths of the second multi-line beam splitter, ……, the m-th multi-line beam splitter and the outgoing optical path of the mirror.

[0023] Further, the probe laser emitted by the laser source is transmitted through the optical fiber and then emitted towards the probe coupling mirror.

[0024] Further, the mirror group includes two mirrors arranged in parallel along the optical path direction.

[0025] Meanwhile, the present invention also provides a method for measuring the shock wave velocity based on the above multi-line imaging type velocity interferometer, which is characterized in that it includes the following steps:

[0026] 1) Obtain the interference image

[0027] 1.1) The probe laser emitted by the laser source is shaped by the probe coupling mirror, then reflected by the probe beam splitter, and focused on the object surface to be measured by the front lens to form a Doppler signal. The Doppler signal reflected from the object surface to be measured is collected and converged by the front lens, and then divided into two beams of Doppler signal light by the signal beam splitter and respectively incident into two heterodyne interference optical path units;

[0028] 1.2) Each beam of Doppler signal light is collimated by the pre-mirror of the interferometer and then incident into the multi-line beam splitter group. The multi-line beam splitter group divides it into N branches. The N branches are respectively imaged on the streak camera through the first heterodyne interference component and N - 1 second heterodyne interference components. Each streak camera obtains N interference images;

[0029] 2) Adjust the interference image

[0030] Rotate the Dove prism of the second heterodyne interference component to rotate the interference image, and swing the mirror group of the second heterodyne interference component to translate the interference image, so that the N interference images on the streak camera are arranged in a "one" shape along the slit direction of the streak camera;

[0031] 3) Obtain the laser fusion shock wave velocity

[0032] Perform physical theoretical model calculations on the two interference images imaged by the two streak cameras through the first heterodyne interference component, and each pair of corresponding interference images imaged by the N - 1 second heterodyne interference components, to obtain N laser fusion shock wave velocity histories.

[0033] Compared with the prior art, the advantages of the present invention are:

[0034] 1. In the present invention, the multi-line beam splitter group of each heterodyne interference optical path unit divides the Doppler signal light into multiple branches. Each branch is imaged on the streak camera through the heterodyne interference component. Through two pairs of corresponding interference images of the two streak cameras, the information of a straight line on the object surface to be measured can be obtained, that is, the information of one laser fusion shock wave velocity history can be obtained. Then, for multiple branches, the information of multiple straight lines can be obtained, that is, the information of multiple laser fusion shock wave velocity histories can be obtained, enriching the information obtained by the multi-line imaging type velocity interferometer, and being more conducive to judging the compression symmetry of the laser fusion spherical fuel.

[0035] 2. In the branch path of the heterodyne interference optical path unit of the present invention after being split by the multi-line beam splitter group, there is a rotatable Dove prism. By rotating it, the direction of the interference image can be changed, and the swinging mirror group changes the position of the interference image formed on the streak camera, so that the interference images on the streak camera are arranged in a "one" shape along the slit direction. Therefore, the images at the slit of the streak camera can be at any angle (in the same direction, perpendicular, etc.); if the two images are in the same direction, the two images can be translated so that they cover different straight lines to obtain the velocity histories of two parallel straight lines on the target surface; if the two images are perpendicular, the velocity histories of two perpendicular straight lines on the target surface can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic structural diagram of the first embodiment of the multi-line imaging velocity interferometer of the present invention;

[0037] Figure 2 is a schematic structural diagram of two interference images in the first embodiment of the multi-line imaging velocity interferometer of the present invention arranged in a "one" shape along the slit direction of the streak camera (streak camera one and streak camera two);

[0038] Among them, the reference numerals are as follows:

[0039] 01 - Laser source, 02 - Heterodyne interference component one, 03 - Heterodyne interference component two, 04 - Heterodyne interference component three, 05 - Heterodyne interference component four, 06 - Multi-line beam splitter group one, 07 - Multi-line beam splitter group two;

[0040] 1 - Optical fiber, 2 - Probe coupling mirror, 3 - Probe beam splitter, 4 - Front-end lens, 5 - Object surface to be measured, 6 - Signal beam splitter, 7 - First primary image plane, 8 - Interferometer pre-mirror one, 9 - Multi-line beam splitter one, 10 - Interferometer one, 11 - Streak camera front imaging mirror one, 12 - Streak camera one, 13 - Mirror one, 14 - Interferometer two, 15 - Dove prism one, 16 - Mirror two, 17 - Mirror three, 18 - Streak camera front imaging mirror two, 19 - Second primary image plane, 20 - Interferometer pre-mirror two, 21 - Multi-line beam splitter two, 22 - Interferometer three, 23 - Streak camera front imaging mirror three, 24 - Streak camera two, 25 - Mirror four, 26 - Interferometer four, 27 - Dove prism two, 28 - Mirror five, 29 - Mirror six, 30 - Streak camera front imaging mirror four. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The content of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0042] Embodiment 1

[0043] As Figure 1As shown in the figure, an embodiment of the present invention provides a multi-line imaging velocity interferometer, which includes an imaging unit and two heterodyne interference optical path units; the two heterodyne interference optical path units are respectively a first heterodyne interference optical path unit and a second heterodyne interference optical path unit.

[0044] The imaging unit includes a laser source 01, a probe coupling mirror 2, a probe beam splitter 3, a front-end lens 4, and a signal beam splitter 6. The signal beam splitter 6 is a dual-sensitivity beam splitter; the probe laser emitted by the laser source 01 is transmitted through the optical fiber 1 and then emitted to the probe coupling mirror 2, and successively transmitted through the probe coupling mirror 2, reflected by the probe beam splitter 3, and transmitted through the front-end lens 4, and then focused on the object surface 5 to be measured to form a Doppler signal. The Doppler signal reflected back by the object surface 5 to be measured is successively transmitted through the front-end lens 4 and the probe beam splitter 3, and then incident on the signal beam splitter 6, and is split into two beams of Doppler signal light by the signal beam splitter 6; the first heterodyne interference optical path unit and the second heterodyne interference optical path unit are respectively located on the two beams of Doppler signal light emitted by the signal beam splitter 6.

[0045] The first heterodyne interference optical path unit includes an interferometer pre-mirror 8, a multi-line beam splitter group 06, a first heterodyne interference component 02, a second heterodyne interference component 03, and a first streak camera 12; the Doppler signal light is transmitted through the interferometer pre-mirror 8 and then incident on the multi-line beam splitter group 06, and is divided into N branches by the multi-line beam splitter group 06, so the number of the second heterodyne interference components 03 is N-1; one of the branches passes through the first heterodyne interference component 02 and is imaged on the first streak camera 12, and the remaining branches respectively pass through N-1 second heterodyne interference components 03 and are also imaged on the first streak camera 12; where N is an integer greater than or equal to 2. The first heterodyne interference component 02 includes an interferometer 10 and a first imaging mirror in front of the streak camera 11 arranged in sequence along the optical path. The second heterodyne interference component 03 includes an interferometer 14, a Dove prism 15, a first mirror group, and a second imaging mirror in front of the streak camera 18 arranged in sequence along the optical path. The first mirror group includes a second mirror 16 and a third mirror 17 arranged in parallel in sequence along the optical path direction; by rotating the Dove prism 15, the direction of the interference image imaged on the first streak camera 12 is changed, and by swinging the second mirror 16 and the third mirror 17, the position of the interference image imaged on the first streak camera 12 is changed, so that the interference images of the first heterodyne interference component 02 and the second heterodyne interference component 03 are arranged in a "one" shape along the slit direction of the first streak camera 12.

[0046] The second difference-frequency interference optical path unit has the same structure as the first difference-frequency interference optical path unit. The second difference-frequency interference optical path unit includes an interferometer pre-mirror two 20, a multi-line beam splitter group two 07, a difference-frequency interference component three 04, a difference-frequency interference component four 05, and a streak camera two 24. The Doppler signal light is transmitted through the interferometer pre-mirror two 20 and then incident on the multi-line beam splitter group two 07. After being split into N branches by the multi-line beam splitter group two 07, the number of difference-frequency interference components four 05 is N - 1. One of the branches passes through the difference-frequency interference component three 04 and is imaged on the streak camera two 24, and the remaining branches respectively pass through N - 1 difference-frequency interference components four 05 and are also imaged on the streak camera two 24. Here, N is an integer greater than or equal to 2. The difference-frequency interference component three 04 includes an interferometer three 22 and a pre-streak-camera imaging mirror three 23 arranged in sequence along the optical path. The difference-frequency interference component four 05 includes an interferometer four 26, a Dove prism two 27, a mirror group two, and a pre-streak-camera imaging mirror four 30 arranged in sequence along the optical path. The mirror group two includes a mirror five 28 and a mirror six 29 arranged parallel to each other along the optical path direction. By rotating the Dove prism two 27, the direction of the interference image imaged on the streak camera two 24 is changed, and by swinging the mirror five 28 and the mirror six 29, the position of the interference image imaged on the streak camera two 24 is changed, so that the interference images of the difference-frequency interference component three 04 and the difference-frequency interference component four 05 are arranged in a "one" shape along the slit direction of the streak camera two 24.

[0047] The multi-line beam splitter group one 06 and the multi-line beam splitter group two 07 have the same structure. As Figure 1 shown, in this embodiment, the multi-line beam splitter group one 06 includes 1 multi-line beam splitter one 9 and 1 mirror one 13 arranged side by side. Then the Doppler signal light is split into 2 branches by the multi-line beam splitter group one 06, and the difference-frequency interference component two 03 is 1. The multi-line beam splitter one 9 is located on the outgoing optical path of the interferometer pre-mirror one 8, and the difference-frequency interference component one 02 is located on the transmitted optical path of the multi-line beam splitter one 9. The mirror one 13 is located on the reflected optical path of the multi-line beam splitter one 9, and the difference-frequency interference component two 03 is located on the outgoing optical path of the mirror one 13.

[0048] The multi-line beam splitter group two 07 includes 1 multi-line beam splitter two 21 and 1 mirror four 25 arranged side by side. Then the Doppler signal light is split into 2 branches by the multi-line beam splitter group two 07, and the difference-frequency interference component four 05 is 1. The multi-line beam splitter two 21 is located on the outgoing optical path of the interferometer pre-mirror two 20, and the difference-frequency interference component three 04 is located on the transmitted optical path of the multi-line beam splitter two 21. The mirror four 25 is located on the reflected optical path of the multi-line beam splitter two 21, and the difference-frequency interference component four 05 is located on the outgoing optical path of the mirror four 25.

[0049] In this embodiment, the interferometer forms a two-channel interference optical path by splitting the interference measurement optical path of the "line imaging VISAR" in a "one-to-two" manner. Consequently, each streak camera obtains two interference images. Secondly, the interference images of the same cluster obtained by the "one-to-two" splitting are arranged in a "one"-shaped pattern along the slit direction of the streak camera. Thirdly, a Dove prism and a mirror are added to the single-channel interference optical path. Rotating the Dove prism can cause the rotation of the final interference image, and swinging the mirror can cause the translation of the interference image. According to requirements, the interference images of each channel are rotated or translated into place. Thus far, the postures (rotation angles or translation amounts) of the interference images in the "one"-shaped queue are different. Finally, the slit of the streak camera intercepts the interference images with different postures and records their velocity histories, enabling the acquisition of more and real compression history information on the surface of the fuel ball to be measured.

[0050] Based on the above shock wave velocity measurement method using a multi-line imaging velocity interferometer, it includes the following steps:

[0051] 1) Obtain interference images

[0052] 1.1) The probe laser emitted by the laser source 01 is shaped by the probe coupling mirror 2, then reflected by the probe beam splitter 3, and focused on the surface of the object to be measured 5 by the front lens 4 to form a Doppler signal. The Doppler signal reflected from the surface of the object to be measured 5 is collected and converged by the front lens 4, and then transmitted through the probe beam splitter 3 and incident on the signal beam splitter 6. The signal beam splitter 6 divides it into two beams of Doppler signal light, which are respectively incident on the first heterodyne interference optical path unit and the second heterodyne interference optical path unit;

[0053] 1.2) The Doppler signal light entering the first heterodyne interference optical path unit first converges on the first primary image plane 7, then is collimated by the interferometer pre-mirror 8 and incident on the multi-line beam splitter group 06. The multi-line beam splitter group 06 divides it into two branches. One branch passes through the heterodyne interference component 02 and images at the slit of the streak camera 12, and the other branch also images at the slit of the streak camera 12 through the heterodyne interference component 03. The streak camera 12 obtains two interference images;

[0054] The Doppler signal light entering the second heterodyne interference optical path unit first converges on the second primary image plane 19, then is collimated by the interferometer pre-mirror 20 and incident on the multi-line beam splitter group 07. The multi-line beam splitter group 07 divides it into two branches. One branch passes through the heterodyne interference component 04 and images at the slit of the streak camera 24, and the other branch also images at the slit of the streak camera 24 through the heterodyne interference component 05. The streak camera 24 obtains two interference images;

[0055] 2) Adjust the interference images

[0056] Rotate the Dove prism 15 of the heterodyne interference component two 03 to rotate the interference image, and swing the mirror two 16 and the mirror three 17 of the heterodyne interference component two 03 to translate the interference image, so that finally the two interference images on the streak camera one 12 are arranged in a "one" shape along the slit direction of the streak camera one 12, as Figure 2 shown, where a is the slit of the streak camera, and b and c are the two interference images respectively;

[0057] And, rotate the Dove prism two 27 of the heterodyne interference component four 05 to rotate the interference image, and swing the mirror five 28 and the mirror six 29 of the heterodyne interference component two 03 to translate the interference image, so that finally the two interference images on the streak camera two 24 are arranged in a "one" shape along the slit direction of the streak camera two 24, as Figure 2 shown, where a is the slit of the streak camera, and b and c are the two interference images respectively;

[0058] 3) Obtain the laser fusion shock wave velocity

[0059] Perform physical theoretical model calculations on the interference image formed by the streak camera one 12 through the heterodyne interference component one 02 and the interference image formed by the streak camera two 24 through the heterodyne interference component three 04, and the information of a straight line on the measured object surface can be obtained, that is, one laser fusion shock wave velocity history information is obtained; and perform physical theoretical model calculations on the interference image formed by the streak camera one 12 through the heterodyne interference component two 03 and the interference image formed by the streak camera two 24 through the heterodyne interference component four 05, and the information of another straight line on the measured object surface can be obtained, that is, one laser fusion shock wave velocity history information is also obtained, and a total of two laser fusion shock wave velocity history information is obtained.

[0060] It can be seen that the velocity history information of any two arbitrarily set straight lines on the fuel ball crown is obtained by using the method of this embodiment, which is more conducive to inferring the compression symmetry of the fuel ball.

[0061] The conventional "linear imaging VISAR" is that the probe laser emits and illuminates the surface to be measured. The laser scattered by the surface to be measured moving at high speed carries Doppler frequency shift information. The frequency-shifted light is split by a beam splitter and enters two difference-frequency interference optical paths respectively. The interference images of the two paths are incident on the slit surfaces of the streak cameras respectively, and the slits intercept a straight line on the image plane for time-scanning recording. Then, the measured data of the two paths are jointly used to solve the target velocity. In this embodiment, the multi-line imaging velocity interferometer divides each of its two difference-frequency interference optical paths (two Doppler signal lights) into two with a multi-line beam splitter group, and then arranges two sets of difference-frequency interference components respectively; the images of the two sets of difference-frequency interference optical paths divided from the same path are arranged in a row along the slit of the streak camera. Since there is a rotatable Dove prism in one path, the direction of the image can be changed by its rotation. Therefore, the two images at the slit of the streak camera can be at any angle (in the same direction, perpendicular, etc.); if the two images are in the same direction, the image can be translated so that they cover different straight lines to obtain the velocity histories of two parallel straight lines on the target surface; if the two images are perpendicular, as Figure 2 shown, the velocity histories of two perpendicular straight lines on the surface to be measured can be obtained. Therefore, the multi-line imaging velocity interferometer in this embodiment expands the information of a single straight line obtained by the original system to the information of any two straight lines, enriching the information obtained by VISAR and being more conducive to judging the compression symmetry of the spherical fuel in laser fusion.

[0062] Embodiment 2

[0063] The difference from Embodiment 1 is that the multi-line beam splitter group 06 includes m multi-line beam splitters Ⅰ arranged side by side and 1 mirror 13, where m is an integer greater than or equal to 2. Then the Doppler signal light is split into m + 1 branches by the multi-line beam splitter group 06, so N = m + 1, and the corresponding m difference-frequency interference components 03 are provided; the m multi-line beam splitters Ⅰ are defined as the first multi-line beam splitter Ⅰ, the second multi-line beam splitter Ⅰ,..., the m-th multi-line beam splitter Ⅰ respectively; the first multi-line beam splitter Ⅰ is located on the outgoing light path of the first pre-mirror 8 of the interferometer, and the difference-frequency interference component 02 is located on the transmitted light path of the first multi-line beam splitter Ⅰ; the mirror 13 is located on the transmitted light path of the m-th multi-line beam splitter Ⅰ, and the m difference-frequency interference components 03 are respectively located on the reflected light paths of the second multi-line beam splitter Ⅰ,..., the m-th multi-line beam splitter Ⅰ and the outgoing light path of the mirror.

[0064] The multi-line beam splitting mirror group II 07 includes m multi-line beam splitting mirrors II arranged side by side and 1 mirror IV 25. Then, the Doppler signal light is split into m + 1 branches by the multi-line beam splitting mirror group II 07, and the corresponding heterodyne interference component IV 05 is m; define the m multi-line beam splitting mirrors II as the first multi-line beam splitting mirror II, the second multi-line beam splitting mirror II, ……, the m-th multi-line beam splitting mirror II respectively; the first multi-line beam splitting mirror II is located on the outgoing light path of the interferometer pre-mirror II 20, and the heterodyne interference component III 04 is located on the transmitted light path of the first multi-line beam splitting mirror II; the mirror IV 25 is located on the transmitted light path of the m-th multi-line beam splitting mirror II, and the m heterodyne interference components IV 05 are respectively located on the reflected light paths of the second multi-line beam splitting mirror II, ……, the m-th multi-line beam splitting mirror II and the outgoing light path of the mirror IV 25.

[0065] In this embodiment, taking m = 3 as an example, the 3 multi-line beam splitting mirrors I are the first multi-line beam splitting mirror I, the second multi-line beam splitting mirror I, and the third multi-line beam splitting mirror I respectively, and the heterodyne interference component II 03 is also 3; the first multi-line beam splitting mirror I is located on the outgoing light path of the interferometer pre-mirror I 8, and the heterodyne interference component I 02 is located on the transmitted light path of the first multi-line beam splitting mirror I; the mirror I 13 is located on the transmitted light path of the third multi-line beam splitting mirror I, and the 3 heterodyne interference components II 03 are respectively located on the reflected light paths of the second multi-line beam splitting mirror I, the third multi-line beam splitting mirror I and the outgoing light path of the mirror I 13. Then, the 3 multi-line beam splitting mirrors II are the first multi-line beam splitting mirror II, the second multi-line beam splitting mirror II, and the third multi-line beam splitting mirror II respectively, and the heterodyne interference component III 04 is also 3; the first multi-line beam splitting mirror II is located on the outgoing light path of the interferometer pre-mirror II 20, and the heterodyne interference component III 04 is located on the transmitted light path of the first multi-line beam splitting mirror II; the mirror IV 25 is located on the transmitted light path of the third multi-line beam splitting mirror II, and the 3 heterodyne interference components IV 05 are respectively located on the reflected light paths of the second multi-line beam splitting mirror II, the third multi-line beam splitting mirror II and the outgoing light path of the mirror IV 25.

[0066] Based on the above shock wave velocity measurement method of the multi-line imaging type velocity interferometer, it includes the following steps:

[0067] 1) Obtain the interference image

[0068] 1.1) The probe laser emitted by the laser source 01 is shaped by the probe coupling mirror 2, then reflected by the probe beam splitting mirror 3, and focused on the object surface to be measured 5 by the front-end lens 4 to form a Doppler signal. The Doppler signal reflected from the object surface to be measured 5 is collected and converged by the front-end lens 4, and then transmitted through the probe beam splitting mirror 3 and incident on the signal beam splitting mirror 6. The signal beam splitting mirror 6 splits it into two beams of Doppler signal light, which are respectively incident on the first heterodyne interference optical path unit and the second heterodyne interference optical path unit;

[0069] 1.2) The Doppler signal light entering the first heterodyne interference optical path unit first converges on the primary image plane 7, and then is collimated by the interferometer pre-mirror 8 and incident on the multi-line beam splitter group 06. After passing through the multi-line beam splitter group 06, it is divided into 4 branches (since m = 3, then N = m + 1 = 4). One of the branches passes through the heterodyne interference component 02 and is imaged at the slit of the streak camera 12, and the other 3 branches respectively pass through 3 heterodyne interference components 03 and are also imaged at the slit of the streak camera 12. The streak camera 12 obtains 4 interference images;

[0070] The Doppler signal light entering the second heterodyne interference optical path unit first converges on the primary image plane 19, and then is collimated by the interferometer pre-mirror 20 and incident on the multi-line beam splitter group 07. After passing through the multi-line beam splitter group 07, it is divided into 4 branches. One of the branches passes through the heterodyne interference component 04 and is imaged at the slit of the streak camera 24, and the other 3 branches respectively pass through 3 heterodyne interference components 05 and are also imaged at the slit of the streak camera 24. The streak camera 24 obtains 4 interference images;

[0071] 2) Adjust the interference images

[0072] Rotate the Dove prism 15 of each heterodyne interference component 03 to rotate the interference image, and swing the mirror 16 and mirror 17 of the heterodyne interference component 03 to translate the interference image. Finally, the 4 interference images on the streak camera 12 are arranged in a "one" shape along the slit direction of the streak camera 12;

[0073] Also, rotate the Dove prism 27 of each heterodyne interference component 05 to rotate the interference image, and swing the mirror 28 and mirror 29 of the heterodyne interference component 03 to translate the interference image. Finally, the 4 interference images on the streak camera 24 are arranged in a "one" shape along the slit direction of the streak camera 24;

[0074] 3) Obtain the laser fusion shock wave velocity

[0075] Define the interference image formed by the first multi-line beam splitter I and the heterodyne interference component 02 as the first interference image A, the interference image formed by the second multi-line beam splitter I and the heterodyne interference component 03 as the second interference image A, the interference image formed by the third multi-line beam splitter I and the heterodyne interference component 03 as the third interference image A, and the interference image formed by the mirror 13 and the heterodyne interference component 03 as the fourth interference image A;

[0076] Moreover, the interference image formed by the first multi-line beam splitter II and the difference-frequency interference component III 04 is the first interference image B, the interference image formed by the second multi-line beam splitter II and the difference-frequency interference component IV 05 is the second interference image B, the interference image formed by the third multi-line beam splitter II and the difference-frequency interference component IV 05 is the third interference image B, and the interference image formed by the mirror IV 25 and the difference-frequency interference component IV 05 is the fourth interference image B;

[0077] The physical theoretical model calculations are respectively performed on the first interference image A and the first interference image B, the second interference image A and the second interference image B, the third interference image A and the third interference image B, and the fourth interference image A and the fourth interference image B to obtain the information of 4 straight lines on the measured object surface, that is, to obtain the information of the velocity histories of 4 laser fusion shock waves.

[0078] In this embodiment, the multi-line imaging type velocity interferometer divides the difference-frequency interference optical paths of its two branches into 4 by the multi-line beam splitter group I 06 and then arranges 4 sets of difference-frequency interference components respectively; the images of the 4 sets of difference-frequency interference optical paths divided from the same branch are arranged in a row along the slit of the streak camera. Since there is a rotatable Dove prism in the branch, the direction of the image can be changed by its rotation. Therefore, the 4 images at the slit of the streak camera can be at any angle (in the same direction, perpendicular, etc.); if the images are in the same direction, the images can be translated so that the two cover different straight lines to obtain the velocity histories of the parallel straight lines on the target surface. Therefore, the multi-line imaging type velocity interferometer in this embodiment expands the information of one straight line obtained by the original system to the information of any number of straight lines, enriches the information volume obtained by the VISAR, and is more conducive to judging the compression symmetry of the laser fusion spherical fuel.

[0079] The above is only a description of the preferred embodiments of the present invention and does not limit the technical solutions of the present invention thereto. Any deformation made by those skilled in the art on the basis of the main technical concept of the present invention belongs to the technical scope to be protected by the present invention.

Claims

1. A multi-line imaging velocity interferometer, characterized in that: It includes an imaging unit and two heterodyne interference optical path units; The imaging unit includes a laser source, a probe coupling mirror, a probe beam splitter, a front-end lens, and a signal beam splitter; the probe laser emitted by the laser source is transmitted through the probe coupling mirror, reflected by the probe beam splitter, and transmitted through the front-end lens in sequence, and then focused on the surface of the object to be measured to form a Doppler signal. The Doppler signal reflected from the surface of the object to be measured is transmitted through the front-end lens, transmitted through the probe beam splitter in sequence, and then incident on the signal beam splitter, and is split into two beams of Doppler signal light by the signal beam splitter; The two heterodyne interference optical path units are respectively located on the two beams of Doppler signal light emitted by the signal beam splitter; Each heterodyne interference optical path unit includes an interferometer pre-mirror, a multi-line beam splitter group, a first heterodyne interference component, a second heterodyne interference component, and a streak camera; the Doppler signal light is transmitted through the interferometer pre-mirror and then incident on the multi-line beam splitter group, and is divided into N branches by the multi-line beam splitter group, where N is an integer greater than or equal to 2; the second heterodyne interference component is N-1; One of the branches passes through the first heterodyne interference component and is imaged on the streak camera, and the remaining branches respectively pass through N-1 second heterodyne interference components and are imaged on the streak camera; The multi-line beam splitter group includes m multi-line beam splitters arranged side by side and 1 reflector, where m = N-1; When N = 2, the multi-line beam splitter is located on the outgoing light path of the interferometer pre-mirror, and the first heterodyne interference component is located on the transmitted light path of the multi-line beam splitter; The reflector is located on the reflected light path of the multi-line beam splitter, and the second heterodyne interference component is located on the outgoing light path of the reflector; When N≥3, the m multi-line beam splitters are respectively the first multi-line beam splitter, the second multi-line beam splitter,..., the m-th multi-line beam splitter; the first multi-line beam splitter is located on the outgoing light path of the interferometer pre-mirror, and the first heterodyne interference component is located on the transmitted light path of the first multi-line beam splitter; the reflector is located on the transmitted light path of the m-th multi-line beam splitter; N-1 second heterodyne interference components are respectively located on the reflected light paths of the second multi-line beam splitter,..., the m-th multi-line beam splitter and the outgoing light path of the reflector; The first heterodyne interference component includes an interferometer one and a first imaging mirror in front of the streak camera arranged in sequence along the optical path; The second heterodyne interference component includes an interferometer two, a Dove prism, a reflector group, and a second imaging mirror in front of the streak camera arranged in sequence along the optical path. By rotating the Dove prism, the direction of the interference image imaged on the streak camera is changed, and by swinging the reflector group, the position of the interference image imaged on the streak camera is changed, so that the interference images of the first heterodyne interference component and the second heterodyne interference component are arranged in a "one" shape along the slit direction of the streak camera.

2. The multi-line imaging velocity interferometer according to claim 1, wherein: The probe laser emitted by the laser source is transmitted through an optical fiber and then emitted to the probe coupling mirror.

3. The multi-line imaging velocity interferometer according to claim 2, characterized in that: The reflector group includes 2 reflectors arranged parallel to each other along the optical path direction.

4. A method for measuring the shock wave velocity based on the multi-line imaging velocity interferometer according to claim 1, characterized in that, It includes the following steps: 1) Obtain an interference image 1.1) The probe laser emitted by the laser source is shaped by the probe coupling mirror, then reflected by the probe beam splitter, and focused on the surface of the object to be measured by the front-end lens to form a Doppler signal. The Doppler signal reflected from the surface of the object to be measured is collected and converged by the front-end lens, and then divided into two beams of Doppler signal light by the signal beam splitter, and are respectively incident on the two heterodyne interference optical path units; 1.2) After each beam of Doppler signal light is collimated by the pre-mirror of the interferometer, it is incident on the multi-line beam splitter group. The multi-line beam splitter group divides it into N branches. The N branches are respectively imaged on the streak camera through the first difference-frequency interference component and N-1 second difference-frequency interference components. Each streak camera obtains N interference images; 2) Adjust the interference images Rotate the Dove prism of the second difference-frequency interference component to rotate the interference images, and swing the mirror group of the second difference-frequency interference component to translate the interference images, so that the N interference images on the streak camera are arranged in a "one" shape along the slit direction of the streak camera; 3) Obtain the laser fusion shock wave velocity Perform physical theoretical model calculations on the two interference images imaged by the first difference-frequency interference component of the two streak cameras and each pair of corresponding interference images imaged by the N-1 second difference-frequency interference components respectively to obtain N laser fusion shock wave velocity histories.

Images