CN112834057A - A multi-window pulse measurement device and method - Google Patents

Abstract

The invention relates to a multi-window pulse measurement device and method, so as to solve the problem that the ultra-short pulse measurement resolution and measurement time window cannot be taken into account in the prior art. The device comprises a laser for generating fundamental frequency laser pulses, a beam splitter arranged on the outgoing optical path of the laser, a step delay unit arranged on the transmission optical path of the beam splitter, a frequency doubling unit arranged on the reflected optical path of the beam splitter, and a The sum-frequency crystal at the intersection of the output optical path of the step delay unit and the frequency doubling unit, the filtering and attenuation unit, the receiving and processing unit, which are sequentially arranged on the output optical path of the sum-frequency crystal. The fundamental frequency laser pulse generated by the laser is split by the beam splitter, the transmitted fundamental frequency light passes through the step delay unit to generate multiple fundamental frequency pulses with different delays, and the reflected fundamental frequency light passes through the frequency doubling unit to generate multiple second harmonics Pulses, two types of pulses are formed by sum-frequency crystals including multiple frequency tripled pulses of multiple windows to be measured, and are received and processed by the receiving and processing unit to obtain the measured pulse waveform.

Description

A multi-window pulse measurement device and method

technical field

The invention relates to the field of pulse measurement, in particular to a multi-window pulse measurement device and method.

Background technique

The pulse width of ultrashort pulses is much smaller than the response time of existing photodetectors. In order to measure the time waveform of ultrashort pulses, the time information of laser pulses is usually converted into spatial information through optical nonlinearity. Indirectly obtain the time information of the pulse. Commonly used measurement methods include intensity autocorrelation method, optical Kerr shutter, frequency resolved optical gate (FROG), spectral phase interference direct electric field reconstruction method (SPIDER) and so on.

For laser pulses with repetition rate, the contrast can be measured by point-by-point scanning. This measurement technology is relatively mature. The measured contrast can reach more than 10 ⁹ , and the measurement time window can reach the order of ns. With the continuous increase of laser energy, the pulse repetition frequency of high-power lasers becomes very low or even in a single-pulse state, which cannot be measured by scanning. Single-pulse measurement generally utilizes the cross-overlap of pulse wavefronts in nonlinear crystals to generate time delays and convert pulse time information into one-dimensional spatial information. However, the cross angle of the two beams is limited by the spatial walk-off effect, phase matching and other conditions, so that the measurement time window is limited.

Limited by the time window and resolution, currently only the time waveform information of large dynamic ultra-short pulses within 200ps can be obtained, and the noise and pre-pulse information beyond 200ps cannot be effectively evaluated; using large dynamic photocells can measure ultra-short pulses in the ns range Due to the limitation of detector resolution, the photocell measurement method will lose waveform information; using gratings, prisms, etalons, etc. to incline the pulse wavefront, the pulse wavefront can be increased without increasing the beam crossing angle. Crossover angles, providing a large time window, but at the expense of measurement resolution. When the pulse bandwidth is very wide, how to increase the measurement window of the ultrashort pulse without sacrificing the measurement resolution, and to solve the problem that the measurement resolution and the measurement time window cannot be taken into account, has important research significance and practical application value .

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the problem that ultrashort pulse measurement resolution and measurement time window cannot be taken into account in the prior art, and provide a multi-window pulse measurement device and method.

The principle of the invention is as follows: in the third-order autocorrelation measurement, the fundamental frequency laser pulse is divided into two beams of transmitted and reflected light waves by a beam splitter, and the transmitted fundamental frequency light is reflected by different stepped reflection end faces of the stepped reflection component to obtain multiple beams with different wavelengths. The delayed fundamental frequency pulse, the reflected fundamental frequency light is obtained by the first type of phase matching through the frequency-doubling crystal to obtain the frequency-doubling pulse. The triple frequency pulse includes multiple windows to be measured. The intensity-related data of the triple frequency pulse received by the CCD in different windows is spliced and synthesized to obtain a pulse waveform with high measurement resolution and large time measurement range.

The technical scheme adopted in the present invention is:

A multi-window pulse measurement device, its special features are:

It includes a laser for generating fundamental frequency laser pulses, a beam splitter arranged on the laser exit light path, a step delay unit arranged on the transmission light path of the beam splitter, a frequency doubling unit arranged on the reflected light path of the beam splitter, The sum-frequency crystal at the intersection of the output optical path of the delay unit and the frequency doubling unit, the filtering and attenuation unit arranged on the output optical path of the sum-frequency crystal, and the receiving and processing unit arranged on the output optical path of the filtering and attenuation unit;

The stepped delay unit includes a stepped reflection component, a first plano-concave cylindrical mirror array and a half-wave plate arranged in sequence along the optical path; the stepped reflection component includes two multi-stage stepped mirrors, the two multi-stage The reflective end surfaces of the stepped reflector correspond one-to-one and are arranged at an included angle, and the incident angles of the light paths are equal; the number of cylindrical reflective surfaces of the first plano-concave cylindrical reflector array is the same as the number of reflective end surfaces of the multi-step stepped reflector;

The frequency doubling unit includes a frequency doubling crystal, a second plano-concave cylindrical mirror array and a first filter arranged in sequence along the optical path; The number of reflecting end faces of the mirror is the same;

The filtering and attenuating unit includes a slit, an attenuator, a relay lens and a polarization beam splitting prism sequentially arranged along the optical path;

The receiving and processing unit includes a second filter, a CCD arranged in sequence along the optical path, and a computer connected to the CCD.

Further, the reflectivity of the multiple reflection end faces of the multi-stage stepped reflector is different.

Further, the sum-frequency crystal and the CCD are conjugated with respect to the relay lens.

Further, the step delay unit further includes a first reflector disposed between the beam splitter and the step reflector assembly for changing the direction of the light path;

The filtering and attenuating unit further includes a second reflector arranged between the attenuator and the relay lens for changing the direction of the light path, and a third reflector disposed between the relay lens and the polarizing beam splitter prism for changing the direction of the light path .

Further, the incident angles of the light paths of the two multi-stage stepped reflectors are both 45°.

Further, the multi-step stepped mirror includes three steps.

A multi-window pulse measurement method, using the above device, is special in that it includes the following steps:

1) The fundamental frequency laser pulse generated by the laser is split into transmitted fundamental frequency light and reflected fundamental frequency light through the beam splitter;

2) The transmitted fundamental frequency light is divided into multiple fundamental frequency pulses with different delays by the multiple reflection end faces of the stepped reflection component, and then adjusted by the first plano-concave cylindrical mirror array to adjust the polarization state through a half-wave plate At the same time, the reflected fundamental frequency light is phase-matched by a frequency doubling crystal to generate a second harmonic pulse, which is then divided and converged by the second plano-concave cylindrical mirror array, and then filtered by the first filter;

3) Multiple fundamental frequency pulses with different delays passing through the half-wave plate and multiple second harmonic pulses passing through the first filter are crossed into the sum-frequency crystal. a third-harmonic pulse whose position changes, the third-harmonic pulse includes a plurality of windows to be measured;

4) After the third harmonic pulse is filtered by the slit, the signal-to-noise ratio of the pulse is proportionally reduced by the attenuation sheet, and then filtered by the relay lens and the polarization beam splitter prism in turn;

5) After the third harmonic pulse passing through the polarizing beam splitting prism is filtered by the second filter, it is received and recorded by the CCD to obtain the pulse data of multiple windows; the intensity-related data in the pulse data of the multiple windows is spliced and synthesized by the computer. processing to obtain the measured pulse waveform.

Further, in step 5), the time interval between two adjacent described windows is T, and the window size Г is greater than T;

By adjusting the step width of the stepped mirror, the time interval T between the windows is adjusted.

Further, in step 2), the phase matching is the first type of phase matching;

In step 3), the phase matching is the first type of phase matching.

Compared with the prior art, the present invention has the following beneficial effects:

The multi-window pulse measurement device provided by the present invention is based on the third-order intensity autocorrelation technology, utilizes a stepped reflection component to generate multi-window pulses with different delays, and combines the multi-window time signal synthesis technology to achieve ultra-short pulse high resolution and large size. Time window measurement: Using the different reflectivity and attenuator of each reflection end face of the multi-stage stepped mirror to adjust the energy of the primary and secondary pulses and reduce the signal-to-noise ratio, so as to realize the measurement of high signal-to-noise ratio pulses by low dynamic range devices.

Description of drawings

1 is a schematic structural diagram of an embodiment of a multi-window pulse measurement device of the present invention;

2 is a schematic structural diagram of a stepped reflection assembly in an embodiment of the multi-window pulse measuring device of the present invention;

3 is a schematic structural diagram of a first plano-concave cylindrical mirror array in an embodiment of the multi-window pulse measurement device of the present invention;

In Fig. 1 to Fig. 3, 1-laser, 2-beam splitter, 3-first reflector, 4-step reflector, 41-multi-step reflector, 411-reflection end face, 5-first plano-concave column Surface mirror array, 51-cylindrical reflection surface, 6-half-wave plate, 7-sum frequency crystal, 8-frequency doubling crystal, 9-second plano-concave cylindrical mirror array, 10-first filter, 11- Slit, 12-attenuator, 13-second mirror, 14-relay mirror, 15-third mirror, 16-polarizing beam splitter prism, 17-second filter, 18-CCD, 19-computer;

FIG. 4 is a cross-overlapping diagram of the pulse wavefront;

Fig. 5 is the schematic diagram of pulse relative delay;

6 is a schematic diagram of the pulse sequence and frequency process of the multi-window pulse measurement method of the present invention;

FIG. 7 is a schematic diagram of the multi-window splicing measurement of the multi-window pulse measurement method of the present invention.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The multi-window pulse measurement device provided by the present invention is shown in FIG. 1 , which includes a laser 1 for generating fundamental frequency laser pulses, a beam splitter 2 arranged on the outgoing optical path of the laser 1 , and a stepped extension mirror arranged on the transmission optical path of the beam splitter 2 . The time unit, the frequency doubling unit arranged on the reflected optical path of the beam splitter 2, the sum-frequency crystal 7 arranged at the intersection of the stepped delay unit and the output optical path of the frequency doubling unit, and the filter attenuation arranged on the output optical path of the sum-frequency crystal 7 unit and a receiving and processing unit arranged on the outgoing light path of the filtering and attenuating unit.

The beam splitter 2 is used to split the fundamental frequency laser pulse generated by the laser 1 into transmitted fundamental frequency light and reflected fundamental frequency light.

The stepped delay unit includes a first reflector 3 , a stepped reflector assembly 4 , a first plano-concave cylindrical reflector array 5 and a half-wave plate 6 arranged in sequence along the optical path.

The first reflection mirror 3 is used to change the direction of the optical path, so that the transmitted fundamental frequency light passing through the beam splitter 2 is incident on the stepped reflection component 4 . As shown in FIG. 2 , the stepped reflection assembly 4 includes two multi-stage stepped mirrors 41 , each stepped end face of the multi-stage stepped mirror 41 is a reflecting end face 411 , and the reflecting end faces 411 of the two multi-stage stepped mirrors 41 are one by one. Correspondingly and arranged at an included angle, the incident angles of the light paths are equal, that is, the light paths incident on the two multi-stage stepped mirrors 41 and the included angles of each reflecting end face 411 are equal, then the light path passing through the first multi-stage stepped mirror 41 Symmetric with the optical path passing through the second multi-stage stepped mirror 41 , the symmetry axis is the bisector of the angle between the extension lines of the reflection end surfaces 411 of the two multi-stage stepped mirrors 41 . After the transmitted fundamental frequency light is reflected by the different stepped reflection end faces 411 of the first multi-stage stepped mirror 41, it is divided into multiple pulses with different time delays, and spatially dislocated, and then passed through the second multi-stage stepped mirror 41. The different steps of the reflective end faces 411 reflect, and the spatial dislocation can be eliminated. In order to facilitate the construction of the optical path, the incident angle of the optical path here is 45°. In this embodiment, the multi-level stepped reflector 41 includes three steps, and the three reflecting end faces 411 of the three steps have different reflectivities, which can be realized by coating each reflecting end face 411 with films with different reflectivities, so as to adjust the divided pulses intensity, reducing the effect of the signal-to-noise ratio. The step width of the multi-step stepped mirror 41 affects the optical path, which in turn affects the delay of each divided pulse. The pulse delay can be adjusted by adjusting the step width as required. The first plano-concave cylindrical mirror array 5 is used to focus multiple fundamental frequency pulses on the sum-frequency crystal 7 respectively. As shown in FIG. 3 , a plurality of cylindrical reflecting surfaces 51 are arranged side by side, and the number is the same as that of the multi-stage stepped reflection. The number of the reflection end surfaces 411 of the mirror 41 is the same, which is also three. The half-wave plate 6 is used to adjust the pulse polarization state.

The frequency doubling unit includes a frequency doubling crystal 8 , a second plano-concave cylindrical mirror array 9 and a first filter 10 arranged in sequence along the optical path.

The frequency doubling crystal 8 is used to perform phase matching on the reflected fundamental frequency light passing through the beam splitter 2 to generate a second harmonic pulse. The second plano-concave cylindrical mirror array 9 is used to divide the second harmonic pulse into multiple beams and focus them on the sum-frequency crystal 7 respectively, so as to improve the nonlinear efficiency. The structure is the same, and the plurality of cylindrical reflection surfaces of the second plano-concave cylindrical mirror array 9 are arranged side by side, and the number is the same as the number of the reflection end surfaces 411 of the multi-stage stepped mirror 41 , which is also three. The first filter 10 is used to filter the passing pulses.

The sum-frequency crystal 7 is used to perform phase matching on multiple beams of fundamental frequency pulses and multiple beams of second harmonic pulses to generate third harmonic pulses.

The filtering and attenuating unit includes a slit 11, an attenuation plate 12, a second mirror 13, a relay mirror 14, a third mirror 15, and a polarizing beam splitting prism 16, which are arranged in sequence along the optical path, and are used to filter and attenuate the third harmonic pulse. .

The receiving and processing unit includes a second filter 17 , a CCD 18 arranged in sequence along the optical path, and a computer 19 connected to the CCD 18 for receiving and processing the third harmonic pulse to realize pulse measurement. The sum-frequency crystal 7 and the CCD 18 are conjugated with respect to the relay lens 14 .

The method for pulse measurement using the above device comprises the following steps:

Step 1: The fundamental frequency laser pulse generated by the laser 1 is split by the beam splitter 2 into transmitted fundamental frequency light and reflected fundamental frequency light.

Step 2: The transmitted fundamental frequency light enters the stepped reflection component 4 through the first reflecting mirror 3, and the transmitted fundamental frequency light is divided into three fundamental frequency pulses with different time delays by the reflection end faces 411 of the two multi-stage stepped reflecting mirrors 41. After the first plano-concave cylindrical mirror array 5 is converged and adjusted, the polarization state is adjusted by the half-wave plate 6; wherein, the transmitted fundamental frequency light is obliquely incident on the first multi-stage stepped mirror 41, which will cause spatial dislocation, and then Oblique incidence to the second multi-step mirror 41, and the spatial misalignment is compensated for.

At the same time, the reflected fundamental frequency light passes through the frequency doubling crystal 8 to generate the second harmonic pulse (frequency doubled pulse) by the first type of phase matching, and then the second harmonic pulse is divided into three parts by the second plano-concave cylindrical mirror array 9 The beam is pulsed and filtered by a first filter 10 .

Step 3: The three fundamental frequency pulses with different delays that pass through the half-wave plate 6 and the three second harmonic pulses that pass through the first filter 10 are focused on the sum-frequency crystal 7 at a certain cross angle, and the One type of phase matching produces third harmonic pulses whose delay varies with spatial position. Among them, the intersection angle between the fundamental frequency pulse and the second harmonic pulse can be obtained according to the phase matching condition, and the optimal angle can be obtained, and the angle is related to many factors such as crystal type, phase matching type, fundamental frequency wavelength, etc.

The three fundamental frequency pulses with different delays and the three second harmonic pulses are matched in phase on the sum-frequency crystal 7 in one-to-one correspondence, forming three windows to be measured. The different optical paths generated by the step widths of the multi-step stepped mirror 41 make the time interval T between the three windows to be measured, and the time interval T of the three windows to be measured can be adjusted by changing the width of the steps.

Step 4: After the third harmonic pulse is filtered by the slit 11, the signal-to-noise ratio of the pulse is reduced proportionally through the attenuation plate 12, and then incident on the relay mirror 14 through the second mirror 13, and incident on the polarization beam splitting through the third mirror 15 Prism 16 performs filtering.

Step 5: After the third harmonic pulse passing through the polarization beam splitting prism 16 is filtered by the second filter 17, it is received and recorded by the CCD 18 to obtain pulse data of multiple windows; Perform splicing, synthesis and processing to obtain the measured pulse waveform. In order to achieve splicing, the window size Г needs to be larger than the time interval T between each window, that is, the partial overlap between two adjacent windows.

FIG. 4 is a cross-overlapping diagram of the pulse wavefronts, wherein the fundamental frequency pulse I ₁ and the second harmonic pulse I ₂ are incident on a nonlinear crystal with a thickness of Lc at a certain cross angle. Since the wavefronts of the two beams are perpendicular to the beam propagation direction, the corresponding pulse wavefronts overlap each other at the same crossing angle as the beams in the crystal. In the x-direction, the wavefronts of the two pulses are gradually separated, resulting in a time delay. At the center of the rhombus, the fundamental frequency pulse I ₁ arrives at the same time as the second harmonic pulse I ₂ without delay. Above the center position, the second harmonic pulse I ₂ is ahead of the fundamental frequency pulse I ₁ , resulting in a negative delay, and the further away from the center position, the greater the delay. Below the center position, the second harmonic pulse I ₂ lags the fundamental frequency pulse I ₁ , resulting in a positive delay.

The corresponding relationship between the pulse time delay τ and the displacement information in the x direction is:

τ=2nx sin(γ/2)/c

where n is the refractive index of the crystal, γ is the cross angle of the beam in the crystal, and c is the speed of light.

It can be seen from the above formula that the time resolution Δτ, that is, the minimum delay amount that can be resolved, is determined by the minimum unit size ds of the detector and the crossing angle γ of the pulse wavefront in the crystal, that is,

Δτ=2nd _s sin(γ/2)/c

Through the above method, the time intensity related signal can be converted into the spatial intensity related signal, and the intensity related signal on the detector is:

G(αx)=C∫I ₁ (αx)[I ₁ (t-αx)] ² dt

in,

α=2n sin(γ/2)/c

C is a constant, I ₁ (αx) is the expression of the fundamental frequency pulse I ₁ , t is the time, and α is the conversion coefficient between the time coordinate and the spatial distribution coordinate.

The time window size Г, that is, the maximum delay amount generated by the wavefront crossing, is determined by the beam diameter D and the cross angle γ in the crystal.

Γ=2nD tan(γ/2)/c

It can be seen that if the beam diameter D and the detector size are fixed, the only way to improve the measurement resolution is to reduce the pulse wavefront crossing angle, but on the other hand, the measurement time window will be reduced accordingly.

Figure 5 shows a schematic diagram of the relative delay of pulses. When one of the beams such as _I1 is adjusted to have a certain delay T relative to _I2 , at this time, the intensity-related signal on the detector produces a corresponding displacement x.

Fig. 6 is a schematic diagram of the sum-frequency process of the pulse sequence of the present invention, wherein, three beams of fundamental frequency pulse sequence and three beams of frequency-doubling pulse sequence are overlapped on the sum-frequency crystal 7 at a certain cross angle to generate three beams of intensity-related signals, respectively. Corresponding to the window to be measured 1 to the window to be measured 3, through the delay adjustment, the fundamental frequency signal of the window to be measured 1 lags behind the frequency multiplier signal by 2T, and the fundamental frequency signal of the window to be measured 2 lags the frequency multiplier signal by a time T, The fundamental frequency signal of the window to be tested 3 is synchronized with the multiplied frequency signal.

Fig. 7 is a schematic diagram showing the splicing measurement of multiple windows in the present invention. A plurality of windows to be measured are formed by the stepped reflection component 4, and the intensity-related data of each window received by the CCD is synthesized and processed to obtain a large time measurement range; The measurement window where each pulse is located is greatly attenuated to reduce the signal-to-noise ratio of related signals, so as to realize the measurement of high-signal-to-noise ratio pulses by low dynamic range devices; in order to achieve splicing, the window size Г needs to be larger than the time interval T between each window .

Claims (9)

1. A kind of multi-window pulse measuring device, characterized by that:

the device comprises a laser (1) for generating fundamental frequency laser pulse, a beam splitter (2) arranged on an emergent light path of the laser (1), a step delay unit arranged on a transmission light path of the beam splitter (2), a frequency doubling unit arranged on a reflection light path of the beam splitter (2), a sum frequency crystal (7) arranged at the intersection of the emergent light paths of the step delay unit and the frequency doubling unit, a filter attenuation unit arranged on the emergent light path of the sum frequency crystal (7) and a receiving and processing unit arranged on the emergent light path of the filter attenuation unit;

the step delay unit comprises a step reflection component (4), a first plano-concave cylindrical reflector array (5) and a half-wave plate (6) which are sequentially arranged along a light path; the step reflection assembly (4) comprises two multi-step reflecting mirrors (41), the reflecting end surfaces (411) of the two multi-step reflecting mirrors (41) are in one-to-one correspondence and arranged in an included angle mode, and the light path incident angles are equal; the number of the columnar reflecting surfaces (51) of the first plano-concave columnar reflecting mirror array (5) is consistent with that of the reflecting end surfaces (411) of the multistage stepped reflecting mirror (41);

the frequency doubling unit comprises a frequency doubling crystal (8), a second plano-concave cylindrical reflector array (9) and a first filter (10) which are sequentially arranged along a light path; the number of the columnar reflecting surfaces of the second plano-concave columnar reflecting mirror array (9) is consistent with that of the reflecting end surfaces (411) of the multistage step reflecting mirrors (41);

the filtering attenuation unit comprises a slit (11), an attenuation sheet (12), a relay lens (14) and a polarization beam splitter prism (16) which are sequentially arranged along a light path;

the receiving and processing unit comprises a second filter (17), a CCD (18) and a computer (19) connected with the CCD (18), wherein the second filter (17) and the CCD (18) are sequentially arranged along a light path.

2. The multi-window pulse measuring device of claim 1, wherein:

the multi-step reflecting mirror (41) has a plurality of reflecting end surfaces (411) having different reflectivities.

3. The multi-window pulse measuring device of claim 2, wherein:

the sum frequency crystal (7) is conjugated with a CCD (18) with respect to a relay mirror (14).

4. A multi-window pulse measuring device according to any one of claims 1 to 3, wherein:

the step delay unit also comprises a first reflecting mirror (3) which is arranged between the beam splitter (2) and the step reflecting component (4) and is used for changing the direction of the light path;

the filtering attenuation unit further comprises a second reflecting mirror (13) arranged between the attenuation sheet (12) and the relay mirror (14) and used for changing the direction of the optical path, and a third reflecting mirror (15) arranged between the relay mirror (14) and the polarization splitting prism (16) and used for changing the direction of the optical path.

5. The multi-window pulse measuring device of claim 4, wherein:

the light path incidence angles of the two multi-stage step reflectors (41) are both 45 degrees.

6. The multi-window pulse measuring device of claim 5, wherein:

the multi-step reflecting mirror (41) includes three steps.

7. A multi-window pulse measurement method using the apparatus of claim 1, comprising the steps of:

1) the fundamental frequency laser pulse generated by the laser (1) is split into transmission fundamental frequency light and reflection fundamental frequency light by the beam splitter (2);

2) the transmission fundamental frequency light is divided into a plurality of fundamental frequency pulses with different delays through a plurality of reflecting end faces (411) of a step reflecting assembly (4), and the polarization state of the transmission fundamental frequency light is adjusted through a half-wave plate (6) after the transmission fundamental frequency light is converged and adjusted through a first plano-concave cylindrical surface reflecting mirror array (5); meanwhile, reflected fundamental frequency light is subjected to phase matching through a frequency doubling crystal (8) to generate second harmonic pulses, and then is divided and converged through a second plano-concave cylindrical reflector array (9), and then is filtered through a first filter (10);

3) a plurality of fundamental frequency pulses with different delays passing through a half-wave plate (6) and a plurality of second harmonic pulses passing through a first filter plate (10) are incident into a sum frequency crystal (7) in a crossed manner, and third harmonic pulses with delays changing along with spatial positions are generated through phase matching of the sum frequency crystal (7), wherein the third harmonic pulses comprise a plurality of windows to be tested;

4) after the third harmonic pulse is filtered by the slit (11), the signal-to-noise ratio of the pulse is proportionally reduced by the attenuation sheet (12), and then the third harmonic pulse is filtered by the relay lens (14) and the polarization beam splitter prism (16) in sequence;

5) the third harmonic pulse passing through the polarization beam splitter (16) is filtered by a second filter (17), and then received and recorded by a CCD (18) to obtain pulse data of a plurality of windows; and splicing, synthesizing and processing the intensity related data in the pulse data of the windows through a computer (19) to obtain the measured pulse waveform.

8. The multi-window pulse measurement method of claim 7, wherein:

in the step 5), the time interval between two adjacent windows is T, and the window size T is larger than T;

the time interval T between the windows is adjusted by adjusting the step width of the step mirror (41).

9. The multi-window pulse measuring method according to claim 7 or 8, characterized in that:

in the step 2), the phase matching is first-class phase matching;

in the step 3), the phase matching is the first type phase matching.

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