Ultra-short and ultra-strong laser pulse measuring device and method

Abstract

The invention provides an ultra-short and ultra-strong laser pulse measuring device and an optical time-space coupling distortion measuring and data processing method based on the device. The device comprises an ultra-short and ultra-strong pulse laser system to be measured, an attenuation module, a beam splitter, a spectral phase measurement unit, a reflector, a micro-lens array, a binary intensity coding plate, a lens, a precision displacement platform, a dispersion element, an imaging lens and a CCD (Charge Coupled Device). The device and the method can be applied to quantitative measurement of ultrashort pulse light space-time coupling distortion.

Description

Technical Field

[0001] This invention relates to the field of ultrashort and ultraintense laser pulses, and more particularly to an ultrashort and ultraintense laser pulse measurement device and method. Background Technology

[0002] Ultrashort, ultra-intense laser pulses (pulse width) or Asia The development of lasers (at the order of magnitude) has brought new research methods and tools to fields such as high-energy-density physics, strong-field physics, and nuclear science. It can also serve as a means and tool to study various transient phenomena, such as nuclear ionization processes, molecular vibrations, and electron acceleration, on ultra-short timescales. However, with the shortening of laser pulse widths, the increase in beam apertures, and the continuous improvement of peak power, effects such as radial group delay, beam dispersion, and spatial chirp are exacerbated. This causes lasers of different frequencies to exhibit different spatial characteristics during transmission and produces pulse broadening in the time domain, resulting in spatiotemporal coupling distortion. This effect is particularly pronounced in large-aperture laser systems.

[0003] Strong spatiotemporal coupling distortion will limit further improvements in peak power density. Accurate measurement of spatiotemporal coupling distortion has always been a key focus and challenge in the development of ultrashort, ultra-intense laser systems. Common methods for measuring spatiotemporal coupling distortion can be broadly categorized into scanning measurement methods and single-shot measurement methods. The scanning measurement method mainly includes: (1) the SEA TADPOLE method proposed by Pamela Bowlan et al. in 2008, which combines single-mode fiber and near-field scanning microprobe, interferes with reference light to obtain spectral phase information, and then scans the spatial position to obtain a three-dimensional light field with a time resolution of fs; (2) the HAMSTER method proposed by Cousin SL et al. in 2012, which combines an acousto-optic programmable dispersion filter (AOPDF) and a Hartmann wavefront sensor to perform frequency domain scanning and then perform three-dimensional reconstruction; (3) the TERITES method proposed by G. Pariente et al. in 2016, which splits the light to be measured into beams using a Michelson interferometer, introduces relative delay using a translation stage, and records the cross-correlation curve using a CCD to realize the self-reference measurement of the three-dimensional light field. The limitation of the scanning measurement method is that it has high requirements for the repetition rate and consistency of the output pulse.

[0004] For large laser devices with low repetition frequency (interval between adjacent shots can be as short as 1 to 2 hours) and large spatiotemporal coupling distortion, single-shot measurement methods are even more necessary. Several typical single-shot measurement methods are briefly described below: (1) The STIPED FISH method proposed by Gabolde P. et al. combines a two-dimensional optical diffraction element (DOE) with a narrowband filter, so that the test light and the reference light of different wavelengths have different spatial solid angles. The wavefront interference pattern of each spectral component is recorded by a CCD, and the wavefront phase and three-dimensional light intensity information can be recovered. The disadvantage of this method is that it requires light with known light field information as a reference, and the calibration is cumbersome. (2) The multispectral Hartmann measurement method proposed by C. Dorrer et al. adds a narrowband filter array of different wavelengths in front of the pixel array of a traditional Hartmann sensor, which can realize single-shot measurement of the wavefront of multiple wavelength components. However, due to the limitations of the filter manufacturing process, the wavelengths that can be measured are limited.

[0005] Currently, there is a lack of methods that can easily and comprehensively measure the three-dimensional optical field (one-dimensional longitudinal time domain and two-dimensional transverse spatial domain) of ultrashort and ultra-intense laser pulses. Summary of the Invention

[0006] In view of this, the present invention proposes an ultra-short, ultra-intense laser pulse measurement device and method.

[0007] This invention provides a device for measuring ultrashort, ultra-intense laser pulses, which can acquire the intensity and phase of the three-dimensional optical field of ultrashort, ultra-intense laser pulses. The device includes a laser system under test, an attenuation module, a beam splitter, a spectral phase measurement unit, a mirror, a microlens array, a binary intensity encoding plate, a lens, a precision displacement platform, a dispersive element, an imaging lens, and a CCD. The laser pulse under test output by the ultrashort and ultraintense pulse laser system is attenuated by the attenuation module and then incident on the beam splitter. The laser pulse under test is split into two beams, laser I and laser II. Laser I is received by the spectral phase measurement unit, and laser II is reflected by the mirror to the surface of the microlens array. The light field obtained by the microlens array is imaged onto the binary intensity encoding board for encoding. The encoded light field is received by the relay lens and then dispersed by the dispersive element to obtain a broadened aliased image. The aliased image is then imaged onto the CCD by the imaging lens. The relay lens is set on the precision displacement platform.

[0008] Furthermore, the spectral phase measurement unit is set as a femtosecond laser pulse measuring instrument or a spectral phase interferometer to measure the spectral phase of the laser pulse under test.

[0009] Furthermore, the substrate material for the binary strength coding plate and coding template is set as a single-crystal silicon plate or a quartz glass plate, and the material used for coating is... The coating thickness reaches the point where the corresponding part of the binary strength coding plate “0” is completely light-blocking.

[0010] Furthermore, the thickness of the coating is .

[0011] Furthermore, the encoding pattern of the binary intensity encoding board is a compressed sensing measurement matrix, which adopts a random Gaussian measurement matrix, a random Bernoulli measurement matrix, a partial Hadamard measurement matrix, or a partial Fourier measurement matrix.

[0012] Furthermore, the dispersive element can be a grating, prism, or prism grid.

[0013] Furthermore, the binary intensity coding plate adopts a binary 0-1 distribution pseudo-randomness, and the sub-lens size of the microlens array is... The minimum cell size of the binary strength coding board coding template is ,in, for multiples of, and The size of a CCD pixel unit is Encoding template pixel size CCD pixel unit size Multiples of integers; the coding template is coated on the template substrate surface according to a 01 distribution, and a single pattern is a side length of... A small square.

[0014] The present invention also provides a method for measuring optical spatiotemporal coupling distortion using the above-mentioned ultrashort and ultraintense laser pulse measurement device, comprising the following steps: S1, the laser pulse to be tested output by the ultra-short ultra-intense pulse laser system is attenuated to an appropriate energy through the attenuation module, which meets the normal response range of the CCD and will not cause damage to the pixel unit of the CCD. S2, adjust the beam splitter and reflector to image laser I of the laser pulse to be measured onto the spectral phase measurement unit, and image the other laser II onto the microlens array mask, and adjust the spot size to cover the microlens area; S3, the position of the binary intensity coding plate is ensured to be parallel to the microlens array, and the distance between the two is adjusted so that the binary intensity coding plate is located on the focal plane of the microlens array. S4, adjust the precision displacement platform below the lens so that the coded focal spot passes through the dispersive element and selects dispersive elements with different dispersive capabilities to adapt to different bandwidths, and then passes through the imaging lens to finally image onto the CCD. S5, select the CCD matching working mode to ensure that a single pulse is captured.

[0015] The present invention also provides a method for processing optical spatiotemporal coupling distortion data using the above-mentioned ultrashort and ultraintense laser pulse measurement device, comprising the following steps: S1, the data acquired by the CCD is divided into several sub-regions according to the division of the microlens array, and each sub-region is processed separately; S2, based on the data from the binary intensity coding board, divide the coding matrix into blocks and diagonalize it, and generate the observation matrix according to the magnitude of the dispersion. ; S3, based on the observation matrix Generate a sparse matrix To ensure maximum sparsity of the signal, a common method is to spatially decompose the light field using a wavelet transform matrix and then frequency-domain decompose it using a discrete cosine transform matrix. Taking the Kronecker product of the two sparse matrices yields the final required sensing matrix. Alternatively, a sparse matrix can be obtained by training a dictionary, combining the sparsity of the measurement matrix and the measured signal, and employing an algorithm. Common methods include... Algorithm. Can achieve better sparsity. Observation matrix. sparse matrix Multiplication, using formula (1): (1) The perception matrix was calculated. , where the parameters g The aliased image received by the CCD, parameters For the three-dimensional light field to be measured in The projection of the corresponding sparse basis. The perceptual matrix can be calculated using formula (1). ; S4. The measurement results are divided into blocks and quantized, combined with the perception matrix. The compressed sensing algorithm is used to solve the underdetermined problem using formula 2): (2) in, Let be the objective function to be optimized. The first part of formula (2) is the weighting factor of the regularization term. The second part represents the difference between the reconstructed image and the actual measurement result. The sparsity of the signal is then measured, and an optimization algorithm is used to find the signal solution that minimizes both parts of the expression. The solution vectors are then rearranged to obtain the complete data cube. S5. Separate the obtained data cube along the spectral direction to obtain the focal spot image of the lens array with different wavelengths. Based on the obtained focal spot image, calculate the centroid distribution of the light field at different frequencies to obtain the overall phase distribution.

[0016] S6, combined with the data measured by the spectral phase measurement unit 4, the spectral phase of the light field to be measured is obtained. Spatial phase obtained by combining focal spot images and spectral phase To obtain the complete three-dimensional phase The measured focal spot light intensity is interpolated and then subjected to a three-dimensional Fourier transform to obtain the time-domain light field of the pulse under test. .

[0017] Beneficial Effects: This invention proposes a global three-dimensional phase retrieval technique based on lens arrays and compressed sensing. It can be applied to the quantitative measurement of spatiotemporal coupling distortion in ultrashort pulse light. This invention can characterize the spatiotemporal coupling effect of femtosecond laser pulses in a single measurement. Under the premise of measuring broadband short pulse lasers of various wavelengths, this method can be used to characterize spatiotemporal coupling distortion at microscale. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the ultrashort, ultra-intense laser pulse measurement device of the present invention; Figure 2 This is a schematic diagram of the encoding template of the binary strength encoding plate of the present invention; In the figure, 1. The ultrashort and ultraintense pulse laser system under test, 2. Attenuation module, 3. Beam splitter, 4. Spectral phase measurement unit, 5. Mirror, 6. Microlens array, 7. Binary intensity encoding plate, 8. Lens, 9. Precision displacement platform, 10. Dispersion element, 11. Imaging lens, 12. CCD. Detailed Implementation

[0019] This invention provides a device for measuring ultrashort, ultra-intense laser pulses, which can acquire the intensity and phase of the three-dimensional optical field of ultrashort, ultra-intense laser pulses. The device includes: 1. an ultrashort, ultra-intense laser pulse system under test; 2. an attenuation module; 3. a beam splitter; 4. a spectral phase measurement unit; 5. a reflector; 6. a microlens array; 7. a binary intensity encoding plate; 8. a lens; 9. a precision displacement platform; 10. a dispersive element; 11. an imaging lens; and 12. a CCD. The laser pulse under test output by the ultra-short and ultra-intense pulse laser system 1 is attenuated by the attenuation module 2 and then incident on the beam splitter 3. The laser pulse under test is split into two beams, laser I and laser II. Laser I is received by the spectral phase measurement unit 4, and laser II is reflected by the reflector 5 to the surface of the microlens array 6. The light field obtained by the microlens array 6 is imaged onto the binary intensity encoding plate 7 for encoding. The encoded light field is received by the relay lens 8 and then dispersed by the dispersive element 10 to obtain a broadened aliased image. The aliased image is then imaged onto the CCD 12 by the imaging lens 11. The relay lens 8 is set on the precision displacement platform 9.

[0020] Furthermore, the spectral phase measurement unit 4 is configured as a femtosecond laser pulse measuring instrument or a spectral phase interferometer to measure the spectral phase of the laser pulse under test.

[0021] Furthermore, the substrate material of the binary strength coding plate 7 coding template is set as a single-crystal silicon plate or a quartz glass plate, and the material used for coating is... The coating thickness reaches the point where the corresponding part of the binary strength coding plate 7"0 is completely light-blocking.

[0022] Furthermore, the thickness of the coating is .

[0023] Furthermore, the encoding pattern of the binary intensity encoding board 7 is a compressed sensing measurement matrix, which adopts a random Gaussian measurement matrix, a random Bernoulli measurement matrix, a partial Hadamard measurement matrix, or a partial Fourier measurement matrix.

[0024] Furthermore, the dispersive element 10 employs a grating, prism, or prism.

[0025] Furthermore, the binary intensity coding plate 7 adopts a binary 01 distribution pseudo-randomness, and the sub-lens size of the microlens array 6 is... The minimum cell size of the binary strength coding board 7 coding template is ,in, for multiples of, and The size of a CCD pixel unit is Encoding template pixel size CCD pixel unit size Multiples of integers; the coding template is coated on the template substrate surface according to a 01 distribution, and a single pattern is a side length of... A small square.

[0026] The present invention also provides a method for measuring optical spatiotemporal coupling distortion using the above-mentioned ultrashort and ultraintense laser pulse measurement device, comprising the following steps: S1, the laser pulse to be tested output by the ultra-short ultra-intense pulse laser system 1 is attenuated to an appropriate energy by the attenuation module 2, which meets the normal response range of CCD12 and will not cause damage to the pixel unit of CCD12. S2, adjust the beam splitter 3 and the reflector 5 to image the laser I of the laser pulse to be measured onto the spectral phase measurement unit 4, and the other laser II to image onto the microlens array 6 mask, and adjust the spot size to cover the microlens area; S3, the position of the binary intensity encoding plate 7 is ensured to be parallel to the microlens array 6, and the distance between the two is adjusted so that the binary intensity encoding plate 7 is located on the focal plane of the microlens array 6. S4, adjust the precision displacement platform 9 below the lens 8 so that the coded focal spot passes through the dispersive element 10 and selects dispersive elements with different dispersive capabilities to adapt to different bandwidths, and then passes through the imaging lens 11 to finally image onto the CCD 12. S5, select the CCD12 matching working mode to ensure that a single pulse is captured.

[0027] The present invention also provides a method for processing optical spatiotemporal coupling distortion data using the above-mentioned ultrashort and ultraintense laser pulse measurement device, comprising the following steps: S1, the data acquired by CCD 12 is divided into several sub-regions according to the division of microlens array 6, and each sub-region is processed separately; S2, based on the data from the binary intensity coding board 7, divide the coding matrix into blocks and diagonalize it, and generate the observation matrix according to the magnitude of the dispersion. ; S3, based on the observation matrix Generate a sparse matrix To ensure maximum sparsity of the signal, a common method is to spatially decompose the light field using a wavelet transform matrix and then frequency-domain decompose it using a discrete cosine transform matrix. Taking the Kronecker product of the two sparse matrices yields the final required sensing matrix. Alternatively, a sparse matrix can be obtained by training a dictionary, combining the sparsity of the measurement matrix and the measured signal, and employing an algorithm. Common methods include... Algorithm. Can achieve better sparsity. Observation matrix. sparse matrix Multiply, and obtain using the formula In the formula, parameter g represents the aliased image received on the CCD, and parameter... For the signal to be measured (i.e., the three-dimensional light field) in The projection of the corresponding sparse basis. The perceptual matrix can be calculated using the formula. ; S4. The measurement results are divided into blocks and quantized, combined with the perception matrix. Compressed sensing algorithm is used to solve underdetermined problems: ,in, Let be the objective function to be optimized. The first part of the expression is the weight factor for the regularization term. The second term represents the difference between the reconstructed image and the actual measurement result. The sparsity of the signal is then measured, and an optimization algorithm is used to find the signal solution that minimizes both parts of the expression. The solution vectors are then rearranged to obtain the complete data cube. S5. Separate the obtained data cube along the spectral direction to obtain the focal spot image of the lens array with different wavelengths. Based on the obtained focal spot, calculate the centroid distribution of the light field at different frequencies to obtain the overall phase distribution.

[0028] S6, combined with the data measured by the spectral phase measurement unit 4, the spectral phase of the light field to be measured is obtained. Spatial phase derived from focal spots and spectral phase To obtain the complete three-dimensional phase The measured focal spot light intensity is interpolated and then subjected to a three-dimensional Fourier transform to obtain the time-domain light field of the pulse under test. .

[0029] Example 1 Specific parameters: Measurement bandwidth 16nm, pulse width on the order of 100fs, single pulse containing spatiotemporal coupling distortion; the selected dispersive element is a grating constant. The grating was selected, and a femtosecond laser pulse measurement instrument (FROG) was chosen as the phase measurement unit.

[0030] Select lens array specifications as The size of the sub-lens is The size of the encoding template unit is The pixel unit size of CCD 12 is After the coded template is dispersed by the grating 10, it is imaged on the CCD 12 by the lens 11. The focal length of the lens 11 is selected as [missing information]. The image is realized on the detector's detection surface. Block-based encoding. That is, one template unit is received by 16 CCD pixels. The encoding method for template 7 is a binary pseudo-random code, obtained by chrome-plating quartz glass, with a coating thickness of [missing information]. The mask size is .

[0031] Specific steps: (1) Attenuate the pulse to be tested from the ultra-short and ultra-intense pulse laser system 1 through the attenuation module 2 to the normal response range of CCD 12 without damaging the pixel units of CCD 12. (2) Adjust the beam splitter 3 and the reflector 5 to image one of the pulses to be tested onto the femtosecond laser pulse measuring instrument (FROG) 4 to measure the spectral phase. Image the other beam onto the microlens array mask 6 and adjust the spot size to basically cover the microlens area. (3) Adjust the position of the encoding template 7 to ensure that it is strictly parallel to the microlens array 6, and adjust the distance between the two so that the encoding template 7 is located on the focal plane of the lens array 6 in order to encode the focal spot to be tested. (4) Adjust the precision displacement platform 9 below the lens 8 so that the coded focal spot is dispersed by the grating 10 and then finally imaged onto CCD 12 by the imaging lens 11. (5) Select an appropriate working mode for CCD 12 to ensure that a single pulse is captured.

[0032] Example 2 Specific parameters: Measurement bandwidth 40nm, pulse width on the order of 30fs, single pulse containing spatiotemporal coupling distortion; the selected dispersive element is the minimum deflection angle. A prism with a refractive index of 1.78 and an Abbe number of 24.76 was used. A femtosecond laser pulse measurement instrument (FROG) was selected as the phase measurement device. The optical path is shown in the figure. Select lens array specifications as The size of the sub-lens is The size of the encoding template unit is The pixel unit size of CCD 12 is After the coded template is dispersed by prism 10, it is imaged at the same size on CCD 12 by lens 11. The focal length of lens 11 is selected as [missing information]. The image is realized on the detector's detection surface. Block-based encoding. That is, one template unit is received by 16 CCD pixels. The encoding method for template 7 is a binary pseudo-random code, obtained by chrome-plating quartz glass, with a coating thickness of [missing information]. The mask size is .

[0033] Specific steps: (1) Attenuate the pulse to be tested from the ultra-short and ultra-intense pulse laser system 1 through the attenuation module 2 to the normal response range of CCD 12 without damaging the pixel units of CCD 12. (2) Adjust the beam splitter 3 and the reflector 5 to image one of the pulses to be tested onto the femtosecond laser pulse measuring instrument (FROG) 4 to measure the spectral phase. Image the other beam onto the microlens array mask 6 and adjust the spot size to basically cover the microlens area. (3) Adjust the position of the encoding template 7 to ensure that it is strictly parallel to the microlens array 6, and adjust the distance between the two so that the encoding template 7 is located on the focal plane of the lens array 6 so as to encode the focal spot to be tested. (4) Adjust the precision displacement platform 9 below the lens 8 so that the focal spot after encoding is dispersed by the prism 10 and then finally imaged onto CCD 12 by the imaging lens 11. (5) Select an appropriate working mode for CCD 12, set the status to video trigger, and select the integration time to 100ms to ensure that a single pulse is captured.

Claims

1. A device for measuring ultrashort, ultra-intense laser pulses, characterized in that, The device includes a short and intense pulsed laser system under test (1), an attenuation module (2), a beam splitter (3), a spectral phase measurement unit (4), a mirror (5), a microlens array (6), a binary intensity encoding plate (7), a lens (8), a precision displacement platform (9), a dispersive element (10), an imaging lens (11), and a CCD (12). The laser pulse to be tested output by the ultra-short and ultra-intense pulse laser system (1) is attenuated by the attenuation module (2) and then incident on the beam splitter (3). The laser pulse to be tested is divided into two beams, laser I and laser II. Laser I is received by the spectral phase measurement unit (4) and laser II is reflected by the mirror (5) to the surface of the microlens array (6). The light field obtained by the microlens array (6) is imaged onto the binary intensity encoding plate (7) for encoding. The encoded light field is received by the relay lens (8) and then dispersed by the dispersive element (10) to obtain a broadened aliased image. The aliased image is then imaged onto the CCD (12) by the imaging lens (11). The relay lens (8) is set on the precision displacement platform (9).

2. The ultra-short, ultra-intense laser pulse measuring device according to claim 1, characterized in that, The spectral phase measurement unit (4) is set to a femtosecond laser pulse measuring instrument or a spectral phase interferometer to measure the spectral phase of the laser pulse to be measured.

3. The ultra-short, ultra-intense laser pulse measuring device according to claim 1, characterized in that, The binary strength coding plate (7) uses a single-crystal silicon plate or quartz glass plate as the base material for the coding template, and the coating material is... The thickness of the coating reaches the point where the corresponding part of the binary strength coding plate (7) "0" is completely light-blocked.

4. The ultrashort, ultra-intense laser pulse measuring device according to claim 3, characterized in that, The thickness of the coating is .

5. The ultra-short, ultra-intense laser pulse measuring device according to claim 1, characterized in that, The encoding pattern of the binary intensity encoding board (7) is a compressed sensing measurement matrix. The measurement matrix adopts a random Gaussian measurement matrix, a random Bernoulli measurement matrix, a partial Hadamard measurement matrix, or a partial Fourier measurement matrix.

6. The ultrashort, ultra-intense laser pulse measuring device according to claim 1, characterized in that, The dispersive element (10) is a grating, prism or prism.

7. The ultra-short, ultra-intense laser pulse measuring device according to claim 1, characterized in that, The binary intensity coding plate (7) adopts a binary 01 distribution pseudo-randomness, and the sub-lens size of the microlens array (6) is... The minimum cell size of the binary strength coding board (7) coding template is ,in, for multiples of, and The size of a CCD pixel unit is Encoding template pixel size CCD pixel unit size Multiples of integers; the coding template is coated on the template substrate surface according to a 01 distribution, and a single pattern is a side length of... A small square.

8. A method for measuring optical spatiotemporal coupling distortion using an ultrashort, ultra-intense laser pulse measurement device as described in any one of claims 1-7, characterized in that, Includes the following steps: S1, the laser pulse to be tested output by the ultra-short ultra-intense pulse laser system (1) is attenuated to an appropriate energy by the attenuation module (2) to meet the normal response range of the CCD (12) and not to damage the pixel unit of the CCD (12); S2, adjust the beam splitter (3) and the reflector (5) to image the laser I of the laser pulse to be measured onto the spectral phase measurement unit (4), and image the other laser II onto the microlens array (6) mask, and adjust the spot size to cover the microlens area; S3, the position of the binary intensity coding plate (7) is ensured to be parallel to the microlens array (6), and the distance between the two is adjusted so that the binary intensity coding plate (7) is located on the focal plane of the microlens array (6); S4, adjust the precision displacement platform (9) below the lens (8) so that the coded focal spot passes through the dispersive element (10), selects dispersive elements with different dispersive capabilities to adapt to different bandwidths, and then passes through the imaging lens (11) to finally image onto the CCD (12). S5, select the CCD (12) matching working mode to ensure that a single pulse is captured.

9. A method for processing optical spatiotemporal coupling distortion data using an ultrashort, ultra-intense laser pulse measurement device as described in any one of claims 1-7, characterized in that, Includes the following steps: S1, the data collected by CCD (12) is divided into several sub-regions according to the division of the microlens array (6), and each sub-region is processed separately; S2, based on the data from the binary intensity coding board (7), divide the coding matrix into blocks and diagonalize it, and generate the observation matrix according to the magnitude of the dispersion. ; S3, based on the observation matrix Generate a sparse matrix To ensure the signal has maximum sparsity, the observation matrix is... sparse matrix Multiplication, using formula (1): （1） The perception matrix was calculated. , where the parameters g The aliased image received by the CCD, parameters For the three-dimensional light field to be measured in The projection of the corresponding sparse substrate; S4. The measurement results are divided into blocks and quantized, combined with the perception matrix. The compressed sensing algorithm is used to solve the underdetermined problem using formula 2): （2） in, Let be the objective function to be optimized. The first part of formula (2) is the weighting factor of the regularization term. The second part represents the difference between the reconstructed image and the actual measurement result. The sparsity of the signal is measured by optimizing the algorithm to find the signal solution that minimizes both parts of formula (2). The solution vectors are then rearranged to obtain the complete data cube. S5. Separate the obtained data cube along the spectral direction to obtain the focal spot image of the lens array of different wavelengths. Calculate the centroid distribution of the light field at different frequencies based on the focal spot image to obtain the overall phase distribution. S6, combined with the data measured by the spectral phase measurement unit (4), the spectral phase of the light field to be measured is obtained. In the formula This refers to the spatial phase obtained by combining the selected position of the spectral phase measurement device with the focal spot image to determine the optical field under test. and spectral phase To obtain the complete three-dimensional phase The measured focal spot light intensity is interpolated and then subjected to a three-dimensional Fourier transform to obtain the time-domain light field of the pulse under test. .

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