Device and method for synchronously measuring time between beams after high-power laser beam splitting

Abstract

The invention relates to an inter-beam time synchronization measurement device and method after high-power laser beam splitting. The device comprises a triple frequency simulation light source, a first photoelectric tube, a second photoelectric tube, a high-speed oscilloscope and a data processing module. The frequency tripling simulation light source provides frequency tripling light signals of all light paths to be measured, the first photoelectric tube receives the light signals to be measured and outputs electric signals to be measured, and the second photoelectric tube receives time reference light signals and outputs time reference electric signals. The high-speed oscilloscope receives the electric signal to be measured and the time reference electric signal and outputs waveform sequence data to the data processing module, and the module calculates the time interval delta t between the waveform sequence data. According to the method, triple frequency simulation light is divided into a plurality of laser beams through a beam splitting module, and each laser beam reaches a target spot through an independent terminal transmission module. A first photoelectric tube is arranged at a target spot to measure the arrival time of each laser beam, and a second photoelectric tube is arranged in a terminal transmission module of a certain split laser beam to serve as a time reference. A light beam to be measured is selected through the shading assembly, and the time interval between each laser pulse and the time reference pulse is calculated by using a cross-correlation analysis method. According to the invention, high-precision measurement of time synchronization between high-power laser beam splitting is realized, and main laser emission or additional devices are not needed.

Description

Technical Field

[0001] The invention belongs to the field of laser technology, and in particular to a device and method for measuring time synchronization between beams after high-power laser beam splitting. The invention relates to time delay measurement of multiple laser beams in a high-power laser system. Background Art

[0002] In the field of high-power laser technology, the damage of terminal optical components under triple frequency (wavelength 351nm) laser irradiation has become a bottleneck problem that limits the improvement of system load capacity, and the threshold of optical component damage induced by the fundamental frequency light (wavelength 1053nm) of the main amplifier section is relatively high. In order to give full play to the gain capability of the fundamental frequency main amplifier system and ensure the safety of the terminal optical components, and at the same time increase the scale of triple frequency light energy output by the laser system to the target, the number of terminal lasers can be increased by the fundamental frequency beam splitting method of the main amplifier output, the fundamental frequency light is divided into multiple beams, and then nonlinear frequency conversion is performed and finally the time domain and spatial domain superposition of multiple beams of triple frequency light are completed at the target point, so as to improve the overall output capacity of the laser system. Since each beam of light after beam splitting reaches the target point through different transmission paths, in order to meet the time delay requirements for the beams to reach the target point in physical experiments, it is necessary to quickly and accurately measure the time synchronization of the beams after beam splitting at the target point.

[0003] In order to perform precise measurement of the time domain superposition of beams at the target point, a high-power laser system is usually required to emit a small-energy laser several times. The time interval between small-energy laser emission is about fifteen minutes. For large systems containing dozens or even hundreds of laser beams, the time cost of the test is relatively high. At the same time, in order to improve the beam-target coupling efficiency, the fundamental frequency light output by the main amplification system of the high-power laser system is usually converted by harmonics through a large-aperture nonlinear crystal to generate tripled frequency light. The harmonic conversion efficiency is closely related to the power density of the fundamental frequency light. When the high-power laser system emits small energy, the harmonic conversion efficiency is less than 10 -5 If a large amount of fundamental frequency light without harmonic conversion enters the target ball, it will cause serious interference to the time synchronization measurement of the triple frequency light. In addition, in the time synchronization measurement using photodetectors and oscilloscopes as the main equipment, although the reading accuracy of specific pulse time points such as pulse peak or rising / falling edge can be improved by reducing the pulse width of the single-peak pulse, the bandwidth limitation of the detection equipment and the jitter of the signal during the acquisition and transmission process limit the ability to improve the time synchronization measurement resolution by aligning short pulses at specific pulse time points.

[0004] Therefore, it is necessary not only to solve the problem of measuring the time synchronization of the light beam after splitting, but also to overcome challenges such as low harmonic conversion efficiency in small energy emission mode and bandwidth limitations of detection equipment, so as to achieve more efficient and precise time-domain superposition control of the light beam. Summary of the invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to propose a device and method for measuring the time synchronization between beams after high-power laser splitting, which uses tripled frequency analog light to perform synchronous measurement between split laser beams, extracts the time interval between each beam of simulated light to the target and the time reference pulse by setting a fixed time reference and adopting a cross-correlation analysis method, and compares the time interval between each beam of laser to the target and the time reference to achieve time synchronization measurement between laser beams.

[0006] To achieve the above objectives, the technical solutions of the present invention are as follows:

[0007] A device for measuring time synchronization between beams after high-power laser beam splitting, characterized in that it comprises:

[0008] A triple frequency simulation light source (101) is used to provide a triple frequency light signal required by each optical path to be measured, and the light source is coaxial with the triple frequency light beam generated by the main laser;

[0009] A first photoelectric tube (2) is arranged at the target point (8) and is used to receive the input optical signal to be measured and convert it into an electrical signal to be measured;

[0010] A second photoelectric tube (3) is arranged in a terminal transmission module (70N) of a split beam laser (60N), and is used to receive an input time reference optical signal and convert it into a time reference electrical signal;

[0011] The high-speed oscilloscope (4) has at least two channels, which are respectively used to receive the electrical signal to be measured and the time reference electrical signal, and output corresponding waveform sequence data.

[0012] The data processing module (10) is used to receive the waveform sequence data to be measured and the time reference waveform sequence data output by the high-speed oscilloscope, and calculate the time interval Δt between the waveform sequence data by means of a cross-correlation analysis method.

[0013] Furthermore, it also includes:

[0014] A beam splitting module (5): used for splitting the triple frequency simulation light into N beam split lasers (601 to 60N);

[0015] N terminal transmission modules (7): each module corresponds to a split laser beam, and is used to transmit the laser to the target point;

[0016] N shading components (7011 to 70N1): respectively arranged in each terminal transmission module, used to select the light beam to be measured that reaches the target, ensuring that only one split laser beam reaches the target and the other split laser beams are blocked.

[0017] Furthermore, the first photoelectric tube and the second photoelectric tube both respond to the triple frequency light beam.

[0018] Furthermore, the triple frequency analog light source (101) is based on a Q-switched laser that performs intracavity or extracavity harmonic conversion to generate a repetition rate pulse laser of several kilohertz and has a plurality of equally spaced small peaks.

[0019] The present invention also provides a method for measuring time synchronization between optical beams using the above-mentioned device for measuring time synchronization between beams after high-power laser beam splitting, which is characterized in that it includes the following steps:

[0020] The triple frequency analog light source in the main amplification system is moved in and used. The triple frequency analog light is divided into multiple beams by the beam splitting module. Each laser beam finally reaches the target through an independent terminal transmission module.

[0021] A first photoelectric tube is arranged at the target point, and the first photoelectric tube measures the time when each beam of simulated light reaches the target point;

[0022] A second photoelectric tube is arranged in a terminal transmission module of a split-beam laser, and the second photoelectric tube receives laser light in a local area within the beam aperture in the optical path as a fixed time reference;

[0023] Adjust the shading components in the terminal transmission module corresponding to each laser beam to select the light beam to be measured to the target, so that only one beam of light reaches the target point, and the remaining beams are blocked by the shading components and do not reach the target;

[0024] The time when the light beam to be measured reaches the target point is measured by using the first photoelectric tube at the target point, and the electric pulse generated by the first photoelectric tube after receiving the light signal is connected to the first channel of the high-speed oscilloscope;

[0025] The electric pulse generated by the second photoelectric tube after receiving the local analog light signal is connected to the second channel of the high-speed oscilloscope. The local sampling beam is used as the time reference signal of the same light source as the waveform measured at the target point. The position and posture of the second photoelectric tube remain unchanged during the measurement process;

[0026] The time interval between each laser pulse at the target and the time reference pulse is calculated based on the cross-correlation analysis method; the first channel or the second channel of the high-speed oscilloscope is selected as the external trigger source of the high-speed oscilloscope. After the high-speed oscilloscope is triggered once, the waveform sequence data of the two channels is recorded and transmitted to the data processing module. The data processing module makes any of the two waveforms traverse the time offset based on the cross-correlation algorithm and calculates the waveform correlation corresponding to each time offset. The target waveform to be measured and the time reference waveform of the same source only have time interval and amplitude differences, and the waveform change law is consistent. At a specific time offset, they should be completely matched to obtain the maximum correlation. The time offset corresponding to the maximum correlation value represents the delay of the beam to be measured relative to the time reference, which is recorded as Δt.

[0027] The same first phototube, second phototube and signal transmission cable connected to a high-speed oscilloscope are used for all split laser beams. The switching of the light beam to the target to be measured is achieved through the shading components in the light paths of each beam. The delay of each laser beam reaching the target point relative to the time reference can be measured respectively. By comparing the delay of each laser beam, time synchronization measurement between high-power laser beams can be achieved.

[0028] The beam splitting module has a comparable splitting ratio for fundamental frequency light and triple frequency simulation light.

[0029] The position and posture of the second photoelectric tube remain unchanged, and the aperture of the second photoelectric tube is smaller than the aperture of the simulated light beam at its position. The second photoelectric tube only receives light from a partial area of ​​the simulated light at this position, and the light beams in other areas can be transmitted to the target point to measure the time delay of the light beam at the target point.

[0030] The technical effects of the present invention are as follows:

[0031] 1) Using triple frequency analog light source for time synchronization measurement, there is no need to occupy the main laser, which has high time efficiency and avoids the interference of other wavelength lasers generated in the harmonic conversion process.

[0032] 2) The cross-correlation analysis method is used to match a large number of time feature points between repetitive pulse waveforms. Compared with the analysis method of aligning specific time points between single-peak pulse waveforms, it has higher measurement accuracy and stability.

[0033] 3) The device has a simple structure, low cost, makes full use of existing equipment of high-power laser systems, is easy to apply in engineering, and can achieve high-precision time synchronization measurement between laser beams without making major changes to the existing system.

[0034] 4) The device and method make full use of the existing tripled frequency analog light source of the high-power laser system without occupying the main laser emission. The cross-correlation analysis quickly matches a large number of pulse time point characteristics and accurately obtains the time interval between pulse signals. It can achieve high-precision measurement of the time delay between beams after laser beam splitting. The principle and structure are simple, the cost is low, and it is easy to implement in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of a time synchronization measurement device for high-power laser beam splitting. Figure 1-main amplification system; 101-tripled frequency analog light source; 2-first phototube; 3-second phototube; 4-high-speed oscilloscope; 401-first channel of high-speed oscilloscope; 402-second channel of high-speed oscilloscope; 5-beam splitting module; 6-beam splitting laser; 601-first beam splitting laser; 602-second beam splitting laser; 60N-Nth beam splitting laser; 7-terminal transmission module; 701-first beam splitting terminal transmission module; 702-second beam splitting terminal transmission module; 70N-Nth beam splitting terminal transmission module; 7011-first beam splitting shading component; 7021-second beam splitting shading component; 70N1-Nth beam splitting shading component; 8-target; 9-signal transmission cable; 10-data processing module.

[0036] Figure 2 This is a flow chart of the time synchronization measurement method between beams after high-power laser beam splitting

[0037] Figure 3 This is a schematic diagram of the waveform measured by an oscilloscope using a triple frequency analog light source.

[0038] 4011-the first channel of the high-speed oscilloscope records the time waveform of the first phototube; 4021-the second channel of the high-speed oscilloscope records the time waveform of the second phototube.

[0039] Figure 4 This is a schematic diagram of the cross-correlation calculation method between repetition frequency pulse waveforms.

[0040] 11- The correlation curve between the repetition rate pulse waveforms and the relative time delay between the waveforms corresponding to the maximum correlation are shown. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with embodiments and drawings, but the protection scope of the present invention shall not be limited thereto.

[0042] Example:

[0043] Figure 1 The present invention is a schematic diagram of a device for measuring time synchronization between beams after high-power laser beam splitting, which includes a triple frequency analog light source 101, a first phototube 2, a second phototube 3, and a high-speed oscilloscope 4. The triple frequency analog light source 101 is used to provide a triple frequency optical signal of each optical path to be measured; the first phototube 2 is used to receive an input optical signal to be measured and output an electrical signal to be measured; the second phototube 3 is used to receive an input time reference optical signal and output a time reference electrical signal; the high-speed oscilloscope 4 is used to receive an input electrical signal to be measured and a time reference electrical signal and output waveform sequence data of the electrical signal to be measured and the time reference electrical signal; the data processing module 10 is used to receive an input waveform sequence data to be measured and a time reference waveform sequence data and output the time interval Δt between the waveform sequence data.

[0044] The first photoelectric tube 2 and the second photoelectric tube 3 must respond to the triple frequency light beam.

[0045] The triple frequency simulation light source 101 is coaxial with the triple frequency light beam generated by the main laser.

[0046] The triple frequency analog light source 101 is generally based on a Q-switched laser for intracavity or extracavity harmonic conversion to generate a repetition rate pulse laser of several thousand Hz, and generally many small peaks at equal intervals will appear.

[0047] Figure 2 The present invention is a flow chart of a method for measuring time synchronization between beams after high-power laser beam splitting, the method comprises the following steps: when measuring time synchronization between laser beam splitting, the triple frequency analog light source 101 in the main amplification system 1 is moved in for use, the triple frequency analog light source 101 is divided into multiple beam splitting lasers 6 by the beam splitting module 5, each laser finally reaches the target point 8 through an independent terminal transmission module 7. A first photoelectric tube 2 is arranged at the target point 8, and the first photoelectric tube 2 measures the time when each beam splitting laser 601 to 60N reaches the target point 8; a second photoelectric tube 3 is arranged in the terminal transmission module (70N) of a certain beam splitting laser (such as 60N), and the second photoelectric tube 3 receives the laser in the local area within the beam aperture of the beam splitting laser (60N) in the optical path as a fixed time reference.

[0048] The light shielding components 7011 to 70N1 in the terminal transmission modules corresponding to the split laser beams 601 to 60N are adjusted to select the light beam to be measured at the target, so that only one split laser beam (such as 601) reaches the target point, and the remaining split laser beams (602 to 60N) are blocked by the corresponding light shielding components (7021 to 70N1) and do not reach the target. The time for the light beam to be measured (601) to reach the target point 8 is measured by the first photoelectric tube 2 at the target point 8, and the electric pulse generated by the first photoelectric tube 2 after receiving the optical signal is connected to the first channel 401 of the high-speed oscilloscope.

[0049] The electric pulse generated by the second photoelectric tube 3 after receiving the local analog light signal of the split laser (60N) is connected to the second channel 402 of the high-speed oscilloscope. The local sampling beam is used as the time reference signal of the same light source as the target point measurement waveform. The position and posture of the second photoelectric tube 3 remain unchanged during the measurement process.

[0050] Finally, the time interval between each laser pulse 601 to 60N at the target 8 and the time reference pulse is calculated based on the cross-correlation analysis method. The first channel 401 of the high-speed oscilloscope or the second channel 402 of the high-speed oscilloscope is selected as the external trigger source of the high-speed oscilloscope 4. After being triggered once, the high-speed oscilloscope 4 records the waveform sequence data of the two channels and transmits it to the data processing module 10. The data processing module 10 makes any waveform of the first channel waveform 4011 of the high-speed oscilloscope and the second channel waveform 4021 of the high-speed oscilloscope traverse the time offset based on the cross-correlation algorithm and calculates the waveform correlation corresponding to each time offset, and finally obtains the correlation curve 11. The target waveform 4011 and the time reference waveform 4021 of the same source only have time interval and amplitude differences, and the waveform change law is consistent. At a specific time offset, they should be completely matched to obtain the maximum correlation. The time offset corresponding to the maximum correlation value represents the delay of the target waveform 4011 to be measured relative to the time reference waveform 4021, which is recorded as Δt.

[0051] For all split lasers 601 to 60N, the same first phototube 2, second phototube 3 and signal transmission cable 9 connected to a high-speed oscilloscope are used. The switching of the target light beam to be measured is achieved through the shading components 7011 to 70N1 in the transmission modules of each split laser terminal. The delay of each split laser 601 to 60N reaching the target point relative to the time reference can be measured respectively. By comparing the delay of each split laser 601 to 60N, time synchronization measurement between high-power laser beams can be achieved.

[0052] The beam splitting module 5 has a comparable splitting ratio for the fundamental frequency light and the triple frequency simulation light.

[0053] The position and posture of the second phototube 3 remain unchanged, and the aperture of the second phototube 3 is smaller than the aperture of the simulated light beam at its position. The second phototube 3 only receives light from a partial area of ​​the simulated light at this position, and the light beams in other areas can be transmitted to the target point 8 to measure the time delay of the light beam at the target point 8.

[0054] The working principle of this device is described as follows.

[0055] High-power laser devices require high-precision measurement and strict control of the time synchronization of multiple laser beams arriving at the target. The present invention provides a device and method for measuring the time synchronization between beams after high-power laser beam splitting. Without the need for main laser firing or adding additional devices, the device and method can achieve high-precision measurement of the delay of each split laser beam arriving at the target relative to the same source time reference by operating according to the following method and steps.

[0056] The device comprises a triple frequency analog light source, a first photoelectric tube, a second photoelectric tube, a high-speed oscilloscope and a data processing module. The triple frequency analog light source is used to provide triple frequency optical signals of each optical path to be measured; the first photoelectric tube is used to receive the input optical signal to be measured and output the electrical signal to be measured; the second photoelectric tube is used to receive the input time reference optical signal and output the time reference electrical signal; the high-speed oscilloscope is used to receive the input electrical signal to be measured and the time reference electrical signal and output the waveform sequence data of the electrical signal to be measured and the time reference electrical signal; the data processing module is used to receive the input waveform sequence data to be measured and the time reference waveform sequence data and output the time interval Δt between the waveform sequence data.

[0057] The first phototube and the second phototube must respond to the triple frequency light beam.

[0058] The tripled frequency simulation light is coaxial with the tripled frequency light beam generated by the main laser.

[0059] The triple frequency simulation light is generally based on a Q-switched laser for intracavity or extracavity harmonic conversion to generate a repetition rate pulse laser of several thousand Hz, and generally there will be many small peaks at equal intervals.

[0060] A method for measuring time synchronization between beams after high-power laser beam splitting includes the following steps: when measuring time synchronization between laser beam splitting, the triple frequency analog light source in the main amplification system is moved in for use, the triple frequency analog light is divided into multiple beams by the beam splitting module, and each laser beam finally reaches the target through an independent terminal transmission module. A first photoelectric tube is set at the target point, and the first photoelectric tube measures the time when each beam of analog light reaches the target point; a second photoelectric tube is set in the terminal transmission module of a certain split laser, and the second photoelectric tube receives the laser in a local area within the beam aperture in the optical path as a fixed time reference.

[0061] The shading components in the terminal transmission module corresponding to each laser beam are adjusted to select the light beam to be measured to the target, so that only one beam of light reaches the target point, and the other beams are blocked by the shading components and do not reach the target. The time when the light beam to be measured reaches the target point is measured by the first photoelectric tube at the target point, and the electrical pulse generated by the first photoelectric tube after receiving the light signal is connected to the first channel of the high-speed oscilloscope.

[0062] The electric pulse generated by the second photoelectric tube after receiving the local analog light signal is connected to the second channel of the high-speed oscilloscope. The local sampling beam is used as the time reference signal of the same light source as the target point measurement waveform. The position and posture of the second photoelectric tube remain unchanged during the measurement process.

[0063] Finally, the time interval between each laser pulse at the target and the time reference pulse is calculated based on the cross-correlation analysis method. The first channel or the second channel of the high-speed oscilloscope is selected as the external trigger source of the high-speed oscilloscope. After the high-speed oscilloscope is triggered once, the waveform sequence data of the two channels is recorded and transmitted to the data processing module. The data processing module makes any of the two waveforms traverse the time offset based on the cross-correlation algorithm and calculates the waveform correlation corresponding to each time offset. The target waveform to be measured and the time reference waveform of the same source only differ in time interval and amplitude, while the waveform change law is consistent. At a specific time offset, they should be completely matched to obtain the maximum correlation. The time offset corresponding to the maximum correlation value represents the delay of the beam to be measured relative to the time reference, which is recorded as Δt.

[0064] The same first phototube, second phototube and signal transmission cable connected to a high-speed oscilloscope are used for all split laser beams. The switching of the light beam to the target to be measured is achieved through the shading components in the light paths of each beam. The delay of each laser beam reaching the target point relative to the time reference can be measured respectively. By comparing the delay of each laser beam, time synchronization measurement between high-power laser beams can be achieved.

[0065] The beam splitting module has a comparable splitting ratio for fundamental frequency light and triple frequency simulation light.

[0066] The position and posture of the second photoelectric tube remain unchanged, and the aperture of the second photoelectric tube is smaller than the aperture of the simulated light beam at its position. The second photoelectric tube only receives light from a partial area of ​​the simulated light at this position, and the light beams in other areas can be transmitted to the target point to measure the time delay of the light beam at the target point.

Claims

1. A device for measuring time synchronization between beams after high-power laser beam splitting, characterized in that: include: A triple frequency simulation light source (101) is used to provide a triple frequency light signal required by each optical path to be measured, and the light source is coaxial with the triple frequency light beam generated by the main laser; A first photoelectric tube (2) is arranged at the target point (8) and is used to receive the input optical signal to be measured and convert it into an electrical signal to be measured; A second photoelectric tube (3) is arranged in a terminal transmission module (70N) of a split beam laser (60N), and is used to receive an input time reference optical signal and convert it into a time reference electrical signal; The high-speed oscilloscope (4) has at least two channels, which are respectively used to receive the electrical signal to be measured and the time reference electrical signal, and output corresponding waveform sequence data. The data processing module (10) is used to receive the waveform sequence data to be measured and the time reference waveform sequence data output by the high-speed oscilloscope, and calculate the time interval Δt between the waveform sequence data by means of a cross-correlation analysis method.

2. The device for measuring time synchronization between beams after high-power laser beam splitting according to claim 1, characterized in that: Also includes: A beam splitting module (5): used for splitting the triple frequency simulation light into N beam split lasers (601 to 60N); N terminal transmission modules (7): each module corresponds to a split laser beam, and is used to transmit the laser to the target point; N shading components (7011 to 70N1): respectively arranged in each terminal transmission module, used to select the light beam to be measured that reaches the target, ensuring that only one split laser beam reaches the target and the other split laser beams are blocked.

3. The device for measuring time synchronization between beams after high-power laser beam splitting according to claim 1 or 2, characterized in that: The first photoelectric tube and the second photoelectric tube are both responsive to the triple frequency light beam.

4. The device for measuring time synchronization between beams after high-power laser beam splitting according to claim 1 or 2, characterized in that: The triple frequency simulation light source (101) is based on a Q-switched laser that performs intracavity or extracavity harmonic conversion to generate a repetition frequency pulse laser of several kilohertz and has a plurality of equally spaced small peaks.

5. A method for measuring time synchronization between optical beams using the device for measuring time synchronization between beams after high-power laser beam splitting according to any one of claims 1 to 4, characterized in that: The following steps are involved: The triple frequency analog light source is moved in for use and divided into multiple split laser beams by a beam splitting module; A first photoelectric tube is arranged at the target point to measure the time when each split laser beam reaches the target point; A second photoelectric tube is arranged in a terminal transmission module of a split-beam laser as a fixed time reference optical signal; By adjusting the shading components in each terminal transmission module, the light beam to be measured is selected to ensure that only one split laser beam reaches the target point; The light beam to be measured is received by the first photoelectric tube and converted into an electrical pulse, and the electrical pulse is then input into the first channel of the high-speed oscilloscope to record and measure the time when the light beam to be measured reaches the target point; At the same time, a second photoelectric tube is used to receive a local analog optical signal in the optical path where the light beam to be measured is located, and the signal is converted into an electrical pulse and input into the second channel of the high-speed oscilloscope to record and measure the time reference optical signal; The data processing module and the cross-correlation analysis method are used to calculate the time interval between each laser pulse and the time reference pulse, thereby realizing the time synchronization measurement between high-power laser beams.

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