CN113984222A - On-line measuring device and method for wavefront distortion of grating compressor - Google Patents
On-line measuring device and method for wavefront distortion of grating compressor Download PDFInfo
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Abstract
The invention discloses an on-line measuring device and a measuring method for wavefront distortion of a grating compressor, which comprises a variable wavelength light source module, a sampling and wavefront measuring module and a computer processing module, wherein the variable wavelength light source module can generate narrow-band collimation wide laser beams with variable central wavelength and inject the narrow-band collimation wide laser beams into a grating compressor to be measured; the computer processing module is in communication connection with the sampling and wavefront measuring module. The invention has the advantage of realizing on-line, quick and high-precision wavefront measurement of the grating compressor to be measured.
Description
Technical Field
The invention relates to the technical field of optical precision measurement, in particular to an on-line measuring device and an on-line measuring method for wavefront distortion of a grating compressor.
Background
Since the first laser appeared in 1960, "shorter pulse width, higher energy" has been an important goal in the development of laser technology. The development of the ultra-high peak power laser technology enables people to create unprecedented extreme state conditions in a laboratory, such as ultra-high temperature black body radiation, ultra-high acceleration, ultra-strong magnetic field and the like, and brings rare development opportunities for the research fields of celestial body physics, laser nuclear fusion, plasma physics and the like.
The ultrahigh peak power laser device is a laser device with peak power reaching the magnitude of a beat watt (PW).
The most important method for obtaining the laser pulse with ultrahigh peak power is the chirped pulse amplification technology proposed in 1985, and the chirped pulse amplification system mainly comprises an oscillator, a stretcher, an amplifier and a compressor. The amplification process is as follows: the method comprises the steps of firstly introducing certain dispersion into low-energy broad-spectrum ultrashort pulse laser output by an oscillator by using a stretcher, widening the laser in time, then amplifying the laser by using an amplifier, so that the time and the space energy density of the laser after amplification can not damage optical elements, and finally introducing dispersion opposite to devices such as the stretcher by using a compressor, and pressing the laser in time to obtain ultrahigh peak power laser pulse. Therefore, the compressor is one of the key components of the chirped pulse amplification system.
The diffraction grating pair is the most commonly used compressor configuration, and generally comprises two pairs of diffraction gratings which are symmetrically arranged or a pair of gratings and a reflector, and different wavelengths of light are superposed on the first surface and the last surface of the grating, and the positions of the different wavelengths of light on the second surface and the third surface of the grating are separated due to the diffraction effect, so that dispersion compensation is realized. In 2019, Zhaoyang Li and the like are firstly proposed in a document of 'Complex spatial incident diffraction pre-compensation with double-compensation for an ultra-intense femtocell laser', because the spatial positions of diffracted lights with different wavelengths on a second surface and a third surface of a grating are inconsistent, different wavefront distortions can be added to the non-ideal diffracted wavefronts of the grating for different wavelengths, and the wavefront distortions can not be compensated by a conventional adaptive optics means, so that a space-time coupling effect is introduced to a compressed ultrahigh peak power laser beam, and the quality and the space-time characteristics of a near-field beam, a far-field spot are seriously influenced. Therefore, accurate measurement of the grating diffraction wavefront is required to compensate by other means.
The diffraction wavefront of the grating is mainly determined by the surface shape error of the grating substrate and the groove processing error, but is influenced by the factors such as the incident angle of the light beam, the diffraction order, the clamping strain and the like. Therefore, for the second and third surface grating diffraction wave fronts which cause the space-time coupling distortion effect in the compressor, the optimal mode is to perform online measurement after the compressor is installed, and the measurement result is completely consistent with the use state. The conventional method for measuring the diffracted wavefront by using an interferometer is only suitable for measuring an off-line single grating, and the influence of the error wavefront of the first surface grating of the compressor, the fourth surface grating of the compressor, other optical elements in a measuring optical path and a system on a measuring result cannot be avoided by only using the wavefront sensor for measuring on line. In addition, in the process of the conventional measurement method, the problems that the measurement wavelength is not matched with the actual use wavelength, the measurement light source is difficult to couple with the built laser system and the like are also encountered.
The present invention has been made based on such a situation.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides a device and a method for measuring the time-space coupling wavefront distortion of an ultrahigh peak power laser device grating compressor installed in a vacuum cavity, and can realize online, quick and high-precision wavefront measurement of the grating compressor to be measured.
The invention can be realized by the following technical scheme:
an on-line measuring device for the wavefront distortion of a grating compressor comprises a variable wavelength light source module, a sampling and wavefront measuring module and a computer processing module, wherein the variable wavelength light source module can generate narrow-band collimation wide laser beams with variable central wavelengths and transmits the narrow-band collimation wide laser beams into a grating compressor to be measured; the computer processing module is in communication connection with the sampling and wavefront measuring module.
The device for online measuring the wavefront distortion of the grating compressor comprises a sampling reflector group, a beam shrinking lens group and a wavefront sensor, wherein the sampling reflector group is used for reflecting a light beam to be measured emitted by the grating compressor to be measured so as to lead the light beam to be measured out; the beam shrinking lens group shrinks the aperture of the light beam to be measured to be consistent with the aperture measured by the wavefront sensor and eliminates chromatic aberration.
The device for online measuring the wavefront distortion of the grating compressor comprises an image acquisition and processing unit and an analysis and processing unit, wherein the image acquisition and processing unit is used for acquiring and processing a wavefront measurement signal diagram of the wavefront sensor, the analysis and processing unit is used for analyzing wavefront information of a plurality of light beams to be measured with different wavelengths so as to obtain the space-time coupling distortion wavefront data of the grating compressor to be measured, and the image acquisition and processing unit is in communication connection with the wavefront sensor.
The device for online measuring wavefront distortion of the grating compressor comprises an oscillator, a stretcher, an amplifier and a spatial filter, wherein the spatial filter comprises an inverted telescope capable of expanding and collimating light beams, and a slit structure capable of moving positions to realize wavelength selection is arranged on a convex mirror of the stretcher.
The invention can also be realized by the following technical scheme:
the method for measuring the wavefront distortion of the grating compressor on line uses the measuring device and comprises the following steps:
adjusting the variable wavelength light source module, and generating a central wavelength λ by using the variable wavelength light source module0The laser beam is incident to the grating compressor to be detected, and the grating compressor to be detected emits the beam to be detected;
b, using a sampling and wavefront measurement module to perform wavefront measurement on the light beam to be measured emitted by the grating compressor to be measured in the step A, wherein the measurement result is W0(x, y), wherein; x and y represent two directions constituting a two-dimensional coordinate system;
c, adjusting the variable wavelength light source module, using the variable wavelength light source module to generate the central wavelengthλ1The laser beam is incident to the grating compressor to be detected, and the grating compressor to be detected emits the beam to be detected; wherein the central wavelength is λ1Of the laser beam with respect to the central wavelength is lambda0The change amount of the wavelength of the laser beam satisfies: the transverse translation amount of the laser beams of the two gratings is equal to the minimum resolution pixel of the wavefront sensor in the sampling and wavefront measuring module after being reduced by the beam reducing lens group when the laser beams are transmitted between the second surface grating and the third surface grating;
d, performing wavefront measurement on the light beam to be measured emitted by the grating compressor to be measured in the step C by using a sampling and wavefront measurement module, wherein the measurement result is W1(x，y)；
E, using a computer processing module to collect and analyze the wavefront data measured in the step C and the step D to obtain an accumulated value W (x, y) of the difference between the two measurement results, wherein
And W (x, y) is the space-time coupling distortion wavefront of the grating compressor to be detected.
The method for measuring the wavefront distortion of the grating compressor on line comprises the following specific steps of: and finally, splicing the calculation results of different spatial positions obtained in the step E in each measurement to obtain the full-aperture wavefront distortion of the large-scale grating compressor to be measured.
In the above method for online measurement of wavefront distortion of a grating compressor, the step a and the step B of adjusting the variable wavelength light source module specifically include the following steps: moving the position of the slit structure causes the wavelength of the variable wavelength light source module to change.
Compared with the prior art, the invention has the following advantages:
the invention can realize the online measurement of the space-time coupling distortion wavefront (namely the variation component of the diffraction wavefronts of the second surface grating and the third surface grating of the grating compressor to be measured in the light beam diffraction direction) of the grating compressor to be measured after being installed and debugged, the arrangement mode of the grating compressor to be measured in the measurement is completely consistent with that in the actual use, and the influence caused by the inconsistency of the incident angle, the element holding mode, the diffraction order and the like in the measurement and the actual use is avoided; in the measuring process, a simple diagnosis system is required to be added, the light source part can be supported by an oscillator and a stretcher of the laser device with ultrahigh peak power, the light path does not need to be adjusted, and the measuring process is simple and convenient. In addition, the measurement mode of subtracting measurement results with different wavelengths is used, the measurement results are insensitive to the system error of an optical system and the inherent error of the wavefront sensor, and extremely high measurement precision and measurement sensitivity can be guaranteed.
Drawings
The following detailed description of embodiments of the invention is provided in conjunction with the appended drawings, in which:
FIG. 1 is a schematic view of the structure of an on-line measuring device of the present invention (the computer processing module is not shown);
FIG. 2 is a simulation measurement result of the on-line measurement method of the time-space coupling distortion wavefront of the grating compressor of the present invention;
FIG. 3 is the experimental measurement result of the on-line measurement method of the time-space coupling distortion wavefront of the grating compressor of the present invention.
Detailed Description
In order to make the technical solutions of the present invention better understood by those skilled in the art, the present invention will be further described in detail with reference to the accompanying drawings and the detailed description.
The device for online measuring the wavefront distortion of the grating compressor comprises a variable wavelength light source module 2 which can generate narrow-band collimation wide laser beams with variable central wavelength and is incident into a grating compressor 1 to be measured, a sampling and wavefront measuring module 3 which can lead out the beams to be measured which are emitted by the grating compressor 1 to be measured and carry out full-aperture beam wavefront measurement on the beams to be measured, and a computer processing module which can obtain information which is acquired by the sampling and wavefront measuring module 3 and obtain the time-space coupling wavefront distortion of the grating compressor 1 to be measured through calculation and analysis, wherein the narrow-band collimation wide laser beams with variable central wavelength are incident into the grating compressor 1 to be measured; the computer processing module is in communication connection with the sampling and wavefront measuring module 3.
As shown in fig. 1, the grating compressor 1 to be tested generally includes four gratings (a first grating 11, a second grating 12, a third grating 13, and a fourth grating 14). Of course, there is a grating compressor using only two gratings (the first grating 11 and the second grating 12), which adds a mirror behind the first grating 11 and the second grating 12 to make the light return to pass through the first grating 11 and the second grating 12 again.
In the invention, a variable wavelength light source module 2 generates a narrow-band collimation wide light beam with variable central wavelength as measuring light, and the measuring light is incident to a grating compressor 1 to be measured; the measuring light is diffracted on the first surface grating 11 of the grating compressor 1 to be measured, the 1 st order diffracted light enters the second surface grating 12, after the diffraction is carried out again, the propagation direction of the 1 st order diffracted light beam is parallel to the direction of the measuring light entering 11, and the 1 st order diffracted light beam is propagated to the third surface grating 13 and the fourth surface grating 14 which are symmetrical to 11 and 12 and then exits the compressor. Except for different positions of the second surface grating 12 and the third surface grating 13, the measuring light with different wavelengths is shared in other positions of the whole measuring light path. The emergent measuring light is sampled by the sampling and wavefront measuring module 3, then wavefront measurement is carried out, and data processing is finished by the computer processing module, so that the space-time coupling distortion wavefront to be measured is obtained.
More specifically, the sampling and wavefront measuring module 3 includes a sampling mirror group 31 for reflecting the light beam to be measured emitted from the grating compressor 1 to be measured, so as to lead out the light beam to be measured, a beam shrinking lens group 32 for shrinking the light beam to be measured is disposed behind the sampling mirror group 31, and a wavefront sensor 33 for measuring the wavefront of the light beam to be measured is disposed behind the beam shrinking lens group 32; the beam shrinking lens group 32 shrinks the aperture of the light beam to be measured to be consistent with the aperture measured by the wavefront sensor 33, and chromatic aberration is eliminated. The light beam to be measured exits the grating compressor 1 to be measured and then enters the sampling and wavefront measuring module 3, and the light beam to be measured is reflected by the sampling mirror 311 and the turning mirror 312, and then passes through the beam contracting lens group 32. The beam reducing lens group 32 reduces the aperture of the light beam to be measured to match the size of the light beam detected by the wavefront sensor 33, i.e. the full aperture of the light beam to be measured falls into the measuring port of the wavefront sensor 33, and the wavefront sensor 33 can perform wavefront measurement. The beam-shrinking lens group 32 is composed of a long-focus achromatic lens 321 and a positive-focus single lens 322, and can image the wavefront position to be measured to a sensor image surface.
Preferably, the wavefront sensor may be any form of high precision wavefront sensor such as a Shark-Hartmann wavefront sensor, shearing interferometer, or the like.
More specifically, the computer processing module includes an image acquisition processing unit for acquiring and processing a wavefront measurement signal diagram of the wavefront sensor 33, and an analysis processing unit for analyzing wavefront information of a plurality of light beams to be detected with different wavelengths to obtain spatiotemporal coupling distortion wavefront data of the grating compressor 1 to be detected, and the image acquisition processing unit is in communication connection with the wavefront sensor 33. That is, the image acquisition processing unit is connected to the wavefront sensor 33 and configured to acquire and process a wavefront measurement signal pattern to obtain wavefront information of incident light with a certain wavelength, and the data analysis and processing unit may analyze wavefront information with multiple wavelengths to obtain a time-space coupling distortion wavefront of the compressor (i.e., wavefront change components of diffracted wavefronts of the second surface grating 12 and the third surface grating 13 of the grating compressor 1 to be measured in the light beam diffraction direction).
More specifically, the variable wavelength light source module 2 includes an oscillator, a stretcher, an amplifier, and a spatial filter, where the spatial filter includes an inverted telescope capable of expanding and collimating the light beam, and a slit structure capable of moving the position to realize wavelength selection is arranged on a convex mirror of the stretcher. Narrow-band light sampling is realized by installing a slit structure in the stretcher, and the adjustment of the central wavelength of the laser beam is realized by moving the position of the slit.
Preferably, the optical components in the variable wavelength light source module 2, the beam shrinking lens group 32 in the sampling and wavefront measuring module 3, and the wavefront sensor 33 all need to be designed achromatically, so as to avoid affecting the measurement result.
The method for measuring the wavefront distortion of the grating compressor on line uses the measuring device and comprises the following steps:
a, adjusting the variable wavelength light source module 2, using the variable wavelength light source module 2 to generate the light with the center wavelength of lambda0The laser beam is incident to the grating compressor 1 to be tested, and the grating compressor 1 to be tested emits the beam to be tested;
b, using a sampling and wavefront measurement module 3 to perform wavefront measurement on the light beam to be measured emitted by the grating compressor 1 to be measured in the step A, wherein the measurement result is W0(x, y), wherein; x and y represent two directions constituting a two-dimensional coordinate system (i.e., the diffraction direction of each wavelength is the x direction, and the vertical diffraction direction of each corresponding grating is the y direction);
c, adjusting the variable wavelength light source module 2, and using the variable wavelength light source module 2 to generate the light with the center wavelength of lambda1The laser beam is incident to the grating compressor 1 to be tested, and the grating compressor 1 to be tested emits the beam to be tested; wherein the central wavelength is λ1Of the laser beam with respect to the central wavelength is lambda0The change amount of the wavelength of the laser beam satisfies: the horizontal translation amount of the laser beams of the two laser beams when the laser beams are transmitted between the second surface grating 12 and the third surface grating 13 is equal to the minimum resolution pixel of the wavefront sensor 33 in the sampling and wavefront measuring module 3 after being shrunk by the beam shrinking lens group 32;
d, using a sampling and wavefront measurement module 3 to perform wavefront measurement on the light beam to be measured emitted by the grating compressor 1 to be measured in the step C, wherein the measurement result is W1(x，y)；
E, using a computer processing module to collect and analyze the wavefront data measured in the step C and the step D to obtain an accumulated value W (x, y) of the difference between the two measurement results, wherein
And W (x, y) is the space-time coupling distortion wavefront of the grating compressor 1 to be detected.
Namely in the step A-the step B,center wavelength of λ0The measuring light enters the grating compressor 1 to be measured, and the sampling and wavefront measuring module 3 performs wavefront measurement to obtain a measuring result W containing system errors and diffraction wavefronts of the first surface grating 11 to the fourth surface grating 14 of the grating compressor 1 to be measured0(x, y), the results are preferably averaged over 10 measurements to eliminate the effect of random errors. Namely, it is
W0(x，y)＝W11&14(x，y)+W12&13(x，y)+Wsystemerror(x，y)
Wherein, W11&14(x, y) is the sum of the diffraction wave fronts of the first surface grating 11 and the fourth surface grating 14, the light spots of the measuring light with different wavelengths are completely overlapped on the two gratings, the introduced wave front distortion is consistent to all the wavelengths, the compensation can be performed by means of adaptive optics and the like, and the space-time coupling distortion is not generated. W12&13(x, y) is the sum of the diffracted wave fronts of the second surface grating 12 and the third surface grating 13, the light spots are separated when different wavelengths of light are diffracted on the surface of the surface grating, different wavelengths of light can generate different wave fronts of the surface grating when the surface of the surface grating 12 and the surface of the surface grating 13 of the surface grating, the surface of the grating, the surface of the surfacesystemerror(x, y) is the cumulative wavefront error introduced by the measured light through all of the optical elements.
In steps C to D, the central wavelength of the measuring light is changed to lambda1And the amount of change in wavelength (wavelength λ)1Of the light beam with respect to the wavelength λ0Wavelength change of the light beam) of the two measuring light beams (wavelength λ)0Of light beam and wavelength lambda1The light beams) travel in the second facet grating 12 and the third facet grating 13 by exactly the same distance in the lateral direction of diffraction as the smallest resolution unit of the wavefront sensor 33 after beam reduction, i.e. the wavelengths of the light beams of the two measurements are guaranteed to be adjacent. The measurement result at this time can be represented as W1(x, y) the wavelength λ1Preferably 10 measurements are averaged to eliminate the effect of random errors. Then
W1(x，y)＝W11&14(x，y)+W12&13(x+1，y)+Wsystemerror(x，y)
The positions of the measuring lights with different wavelengths except the second surface grating 12 and the third surface grating 13 are overlapped, so that the system error in the two measurements and the diffraction wave fronts of the first surface grating 11 and the fourth surface grating 14 are completely consistent.
In step E, subtracting the two measurement results, so as to remove the influence of the system error and the diffracted wavefronts of the first surface grating 11 and the fourth surface grating 14, and obtain the gradient distribution of the diffracted wavefronts of the light beam on the second surface grating 12 and the third surface grating 13 with the transverse direction as the displacement direction (here, the x direction), that is:
W1(x，y)-W0(x，y)＝W12&13(x+1，y)-W12&13(x，y)
accumulating the gradient values line by line to recover the space-time coupling distortion wavefront to be detected, namely:
more specifically, the measurement of the large-scale grating compressor 1 to be measured, in which the aperture of the emergent light beam after being reduced by the reduction lens group 32 exceeds the maximum aperture of the light beam that can be measured by the wavefront sensor 33, includes the following specific steps: and measuring the large-scale grating compressor 1 to be measured for a plurality of times, wherein each measuring step comprises the steps A to E, the central wavelengths of the laser beams used in the step A in each measurement are different, and finally, the calculation results of different spatial positions obtained in the step E in each measurement are spliced to obtain the full-aperture wavefront distortion of the large-scale grating compressor 1 to be measured. For full-aperture space-time coupling distortion wavefront measurement of a large grating compressor, the central wavelength of a measurement light source can be adjusted, the position of the measurement light irradiated on a grating is changed, multiple measurements are carried out to obtain the gradient distribution of the wavefront at different positions of the grating compressor, and finally full-aperture wavefront distortion is obtained through splicing.
More specifically, the step a and the step B of adjusting the variable wavelength light source module 2 specifically include the following steps: moving the position of the slit structure causes the wavelength of the variable wavelength light source module 2 to change. The invention can realize the online measurement of the space-time coupling distortion wavefront (namely the variation component of the diffraction wavefronts of the second surface grating 12 and the third surface grating 13 of the grating compressor to be measured in the light beam diffraction direction) of the grating compressor 1 to be measured after being installed and debugged, the arrangement mode of the grating compressor 1 to be measured in the measurement is completely consistent with that in the actual use, and the influence caused by the inconsistency of the incident angle, the element holding mode, the diffraction order and the like in the measurement and the actual use is avoided; in the measuring process, a simple diagnosis system is required to be added, the light source part can be supported by an oscillator and a stretcher of the laser device with ultrahigh peak power, the light path does not need to be adjusted, and the measuring process is simple and convenient. In addition, the measurement mode of subtracting measurement results with different wavelengths is used, the measurement results are insensitive to the system error of an optical system and the inherent error of the wavefront sensor, and extremely high measurement precision and measurement sensitivity can be guaranteed.
The first embodiment is as follows:
the apparatus and method of the present invention is now used to perform simulation measurements of the spatiotemporal coupling aberrated wavefront of a grating compressor. The designed center wavelength of the grating compressor to be measured is 800nm, the grating line logarithm is 1740 lines/mm, the incidence angle of the compressor is 53 degrees, and the chirp rate is 40 ps/nm. The measurement uses a 0.15mm Shark-Hartmann wavefront sensor lenslet size, a 32X 32 resolution, and a 4.8mm X4.8 mm total detection area. The magnification of the beam-shrinking system is 20 times, so the measuring aperture is 96mm multiplied by 96mm, the wavefront transverse resolution in the measurement is 3mm, and the corresponding wavefront change amount is 1.15nm near the central wavelength. The diffracted wavefronts of the second surface grating 12 and the third surface grating 13 causing the space-time coupling distortion to be measured are shown in fig. 2(a), the accumulated diffracted wavefronts of the first surface grating 11 and the fourth surface grating 14 are shown in fig. 2(b), the measuring light with the wavelength of 800nm and the wavelength of 798.85nm respectively passes through the grating compressor during the measurement, the transverse displacement occurs in the X direction, and finally, the measurement results obtained on the Shark-Hartmann wavefront sensor are shown in fig. 2(c) and (d), and the spectral width of the measuring light is 1 nm. The wavefront results of 2 measurements were differenced to obtain a gradient distribution result, as shown in fig. 2 (e). The gradient distribution results are then accumulated row by row along the X direction, and the measurement result is obtained as shown in fig. 2 (f). Since the initial value of X is 0, the measurement result will have uniform deviation for each row, which is an overall error distribution along the Y direction, as shown in fig. 2 (g). However, the overall distribution does not bring a space-time coupling effect, because the influence on different wavelengths is the same, the compensation can be realized through adaptive optics such as a deformable mirror, under the condition of neglecting non-space-time coupling distorted wavefront, the measured error distribution is as shown in fig. 2(h), the RMS value of the measured error is only 6.8nm, and the RMS value is converted into a wavelength unit smaller than lambda/100, so that the high-precision measurement of the space-time coupling distorted wavefront can be realized. On the other hand, because the measurement error is mainly concentrated on the high-frequency component, and the high-frequency component has little influence on the focusing effect of the ultrahigh peak power laser, the high-precision low-frequency component is obtained for measurement, and the focusing quality of the ultrahigh peak power laser can be further improved.
Example two:
the device and the method of the invention are used for carrying out experimental measurement on the space-time coupling distortion wavefront of a grating compressor, and the parameters of the compressor to be measured and the measuring device are completely consistent with the simulation measurement. In the experiment, the laser light generated by the variable wavelength light source module 1 was monitored using a fiber optic spectrometer, the spectral width was controlled to 1.25nm, and the measurement was performed at two wavelengths of 804.6nm and 805.75nm spaced apart by 1.15nm, and the measurement results are shown in fig. 3(a) and 3 (b). The wavefront results of 2 measurements were subtracted to obtain the gradient distribution results shown in fig. 3 (c). The gradient distribution results are then accumulated row by row along the X direction to obtain the measurement result as shown in fig. 3 (d). The space-time coupling distortion wavefront caused by the second surface grating 12 and the third surface grating 13 is successfully recovered in the measurement result, obvious grating splicing seams can be seen on the right side from the gradient distribution and accumulation results, and the used gratings are double-spliced gratings, so that the correctness of the experimental result is verified.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (7)
1. The utility model provides a grating compressor wave front distortion on-line measuring device which characterized in that: the device comprises a variable wavelength light source module (2) which can generate narrow-band collimation wide laser beams with variable central wavelength and is incident into a grating compressor (1) to be measured, a sampling and wavefront measuring module (3) which can lead out the beams to be measured which are emitted by the grating compressor (1) to be measured and carry out full-aperture beam wavefront measurement on the beams to be measured, and a computer processing module which can obtain information which is acquired by the sampling and wavefront measuring module (3) and obtain the time-space coupling wavefront distortion of the grating compressor (1) to be measured through calculation and analysis; the computer processing module is in communication connection with the sampling and wavefront measuring module (3).
2. The on-line measuring device for wavefront distortion of a grating compressor as recited in claim 1, wherein: the sampling and wavefront measuring module (3) comprises a sampling reflector group (31) for reflecting a light beam to be measured emitted by the grating compressor (1) to be measured so as to lead the light beam to be measured out, a beam shrinking lens group (32) for shrinking the light beam to be measured is arranged behind the sampling reflector group (31), and a wavefront sensor (33) for measuring the wavefront of the light beam to be measured is arranged behind the beam shrinking lens group (32); the beam shrinking lens group (32) shrinks the caliber of the light beam to be measured to be consistent with the caliber measured by the wavefront sensor (33) and eliminates chromatic aberration.
3. The on-line measuring device for wavefront distortion of a grating compressor as claimed in claim 2, wherein: the computer processing module comprises an image acquisition processing unit and an analysis processing unit, wherein the image acquisition processing unit is used for acquiring and processing a wavefront measurement signal diagram of the wavefront sensor (33), the analysis processing unit is used for analyzing wavefront information of a plurality of light beams to be detected with different wavelengths so as to obtain space-time coupling distortion wavefront data of the grating compressor (1) to be detected, and the image acquisition processing unit is in communication connection with the wavefront sensor (33).
4. The on-line measurement device for wavefront distortion of a grating compressor as claimed in any one of claims 1 to 3, wherein: the variable wavelength light source module (2) comprises an oscillator, a stretcher, an amplifier and a spatial filter, wherein the spatial filter comprises an inverted telescope capable of expanding and collimating light beams, and a slit structure capable of moving positions to realize wavelength selection is arranged on a convex mirror of the stretcher.
5. An on-line measurement method of wavefront distortion of a grating compressor, which uses the measurement device of claim 4, comprising the steps of:
a, adjusting the variable wavelength light source module (2), and using the variable wavelength light source module (2) to generate the light with the center wavelength of lambda0The laser beam is incident into the grating compressor (1) to be tested, and the grating compressor (1) to be tested emits the beam to be tested;
b, using a sampling and wavefront measurement module (3) to perform wavefront measurement on the light beam to be measured emitted by the grating compressor (1) to be measured in the step A, wherein the measurement result is W0(x, y), wherein; x and y represent two directions constituting a two-dimensional coordinate system;
c, adjusting the variable wavelength light source module (2), and using the variable wavelength light source module (2) to generate the light with the center wavelength of lambda1The laser beam is incident into the grating compressor (1) to be tested, and the grating compressor (1) to be tested emits the beam to be tested; wherein the central wavelength is λ1Of the laser beam with respect to the central wavelength is lambda0The change amount of the wavelength of the laser beam satisfies: the transverse translation amount of the laser beams of the two gratings is equal to the minimum resolution pixel of a wavefront sensor (33) in the sampling and wavefront measuring module (3) after being condensed by a condensing lens group (32) when the laser beams are transmitted between the second surface grating (12) and the third surface grating (13);
d, performing wavefront measurement on the light beam to be measured emitted by the grating compressor (1) to be measured in the step C by using a sampling and wavefront measurement module (3), wherein the measurement result is W1(x,y)；
E, using a computer processing module to collect and analyze the wavefront data measured in the step C and the step D to obtain an accumulated value W (x, y) of the difference between the two measurement results, wherein
And W (x, y) is the space-time coupling distortion wavefront of the grating compressor (1) to be detected.
6. The method for on-line measuring the wavefront distortion of the grating compressor as claimed in claim 5, wherein the measurement of the large-scale grating compressor (1) to be measured, the caliber of which after the emergent light beam is reduced by the reducing lens group (32) exceeds the maximum caliber of the light beam which can be measured by the wavefront sensor (33), comprises the following specific steps: and measuring the large-scale grating compressor (1) to be measured for a plurality of times, wherein each measuring step comprises the steps A to E, the central wavelengths of the laser beams used in the step A in each measurement are different, and finally, the calculation results of different spatial positions obtained in the step E in each measurement are spliced to obtain the full-aperture wavefront distortion of the large-scale grating compressor (1) to be measured.
7. The method for on-line measurement of wavefront distortion of a grating compressor as claimed in claim 5, wherein the step A and the step B of adjusting the variable wavelength light source module (2) specifically comprises the following steps: the position of the slit structure is moved so that the wavelength of the variable wavelength light source module (2) is changed.
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