A method for measuring inter-beam delay of high power laser beams

Abstract

The application discloses a high-power laser beam inter-delay measurement device, when the relative time delay is measured in a base frequency band, a signal emitted by a clock reference is connected to a first channel of a high-speed oscilloscope in an electrical signal mode, and a pulse output by a main laser system with a high repetition frequency is received by a first photoelectric tube and converted into an electrical pulse and connected to a second channel of the high-speed oscilloscope; when the relative time delay is measured in a three times frequency band, three times frequency analog light is received by a second photoelectric tube after passing through terminal optical elements and converted into an electrical pulse and connected to a third channel of the high-speed oscilloscope. The application measures the time delay by segmenting and dividing wavelengths, and finally accumulates the total delay to determine the time delay of each light beam relative to the reference at a target point. The high-precision measurement of the inter-beam delay can be realized without adding new equipment by using the existing main laser system with a high repetition frequency, three times frequency analog light source and other equipment, the principle and structure are simple, the cost is low, and the engineering implementation is easy.

Description

Technical Field

[0001] This invention belongs to the field of laser technology, and in particular to a device and method for measuring the time delay between high-power laser beams. The invention relates to the measurement and adjustment of time delay in multi-beam high-power laser systems. Background Technology

[0002] In the field of high-power laser technology, physics experiments often require multiple laser beams to reach the target simultaneously. Since the high-energy emission time interval of high-power lasers is typically several hours, and the emission cost is high, to improve the efficiency of precise adjustment of multi-laser time synchronization and save costs, high-energy laser beams are generally not used for precise measurement of inter-beam delay. The usual practice is to use other methods, such as low-energy indirect methods, to precisely measure and adjust the inter-beam delay. If necessary, a high-energy emission is then performed for confirmation and further error elimination. If the accuracy of precise measurement and adjustment of inter-beam delay using low-energy indirect methods can reach a high level and has high implementation efficiency, then high-energy emission can be eliminated while ensuring beam synchronization accuracy.

[0003] High-power laser systems typically use large-aperture neodymium glass as the amplification medium, with an output laser center wavelength generally around 1053 nm, known as the fundamental frequency. To improve beam-target coupling efficiency, a large-aperture nonlinear crystal is typically used as a harmonic conversion module to convert the fundamental frequency beam into a harmonic or third harmonic. The nonlinear crystal is optimized based on the power density characteristics of the fundamental frequency output of the high-power laser device, and the harmonic conversion efficiency is closely related to these power density characteristics. At high-energy emission, the harmonic conversion efficiency can generally exceed 60%. However, the laser power density used for debugging is typically more than three orders of magnitude lower than that at high-energy emission. The third harmonic energy generated after conversion by the nonlinear crystal is generally more than nine orders of magnitude lower. Furthermore, if the unconverted fundamental frequency beam enters the target sphere, it will create significant noise on the detection surface, exceeding the third harmonic signal by several orders of magnitude. This will severely interfere with the measurement results of the time waveforms of various beams. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the purpose of this invention is to propose a high-power laser beam delay measurement device and method, which measures the time delay by segmenting and wavelength, and finally accumulates the total delay to determine the time delay of each beam relative to a reference.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A device and method for measuring the inter-beam delay of a high-power laser is characterized in that the device includes a clock reference, a high-speed oscilloscope, a first phototube, a second phototube, a repetition rate main laser system, and a third harmonic analog light. When performing time delay measurements segmented by wavelength, the process is completed in two stages: relative time delay measurement in the fundamental frequency band and relative time delay measurement in the third harmonic band.

[0007] During the relative time delay measurement in the fundamental frequency band, the signal emitted by the clock reference is ultimately input to the first channel of the high-speed oscilloscope as an electrical signal, serving as a reference point for the fundamental frequency time delay. The output pulse of the repetition rate main laser system is received by the first phototube before reaching the harmonic conversion module after passing through the high-power laser system. The electrical pulse generated by the first phototube is input to the second channel of the high-speed oscilloscope. Either the first channel or the second channel of the oscilloscope is selected as the external trigger source for the oscilloscope, and the delay of the waveforms in the first and second channels of the oscilloscope after one trigger is recorded as Δt1.

[0008] During the relative time delay measurement at the third harmonic band, the third harmonic analog light is incident in front of the harmonic conversion module, and after passing through the terminal optical components such as the harmonic conversion module, it converges to the target point. A second photodiode is placed at the target point, and the electrical pulse generated by the second photodiode is connected to the third channel of the high-speed oscilloscope. The second or third channel of the oscilloscope is selected as the external trigger source of the oscilloscope, and the delay of the waveforms of the second and third channels of the oscilloscope after one trigger is recorded as Δt2.

[0009] Finally, the total delay is accumulated to determine the time delay of each main laser beam reaching the target point relative to the reference as Δ = Δt1 + Δt2 + δ, where δ is a fixed deviation that is related to the first phototube, the second phototube, and their cables connected to the oscilloscope. For multiple laser beams, the same first phototube, the second phototube, and their cables connected to the oscilloscope are used. By repeating the above steps, the time delay of each beam reaching the target point relative to the clock reference can be measured separately.

[0010] The first phototube must respond to both the fundamental frequency beam and the third harmonic beam.

[0011] The delay of the output pulse of the repetition rate master laser system relative to the clock reference does not change with time.

[0012] The third-harmonic simulated light is coaxial with the third-harmonic beam generated by the main laser.

[0013] The third harmonic analog light is generally based on a Q-switched laser that performs internal or external harmonic conversion to generate a repetitive pulse laser of several kilohertz, and usually exhibits many equally spaced small spikes.

[0014] The position and orientation of the first phototube remain unchanged when measuring the relative time delay in the fundamental frequency band and the relative time delay in the third harmonic band.

[0015] Compared with the prior art, the technical effects of the present invention are as follows:

[0016] The time delay is measured by segmenting and wavelength, and finally the total delay is accumulated to determine the time delay of each main laser beam reaching the target point relative to the reference.

[0017] By utilizing existing high-repetition-rate master laser systems, third-harmonic analog light sources, and other equipment, high-precision measurement of inter-beam delay can be achieved without the need for additional equipment. The principle and structure are simple, the cost is low, and it is easy to implement in engineering. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the high-power laser beam delay measurement device of the present invention, wherein a is a schematic diagram of relative time delay measurement in the fundamental frequency band, and b is a schematic diagram of relative time delay measurement in the third harmonic frequency band.

[0019] In the diagram: 1-Clock reference; 2-High-speed oscilloscope; 201-High-speed oscilloscope first channel; 202-High-speed oscilloscope second channel; 203-High-speed oscilloscope third channel; 3-First phototube; 4-Second phototube; 5-Frequency main laser system; 6-Third harmonic analog light; 7-Harmonic conversion module; 8-Main laser before harmonic conversion module; 9-Beam after harmonic conversion module; 10-Third harmonic analog light before harmonic conversion module; 11-Third harmonic analog light after harmonic conversion module.

[0020] Figure 2 A schematic diagram of the time delay measurement relative to the fundamental frequency band.

[0021] In the figure: 2011 - Schematic diagram of the clock reference waveform of the first channel of the high-speed oscilloscope; 2021 - Schematic diagram of the time waveform of the first phototube recorded by the second channel of the high-speed oscilloscope and the relative time delay during the fundamental frequency band time measurement.

[0022] Figure 3 A schematic diagram of the time delay measurement in the third harmonic band relative time delay.

[0023] The diagram shows: 2022 - the second channel of the high-speed oscilloscope recording the time waveform and relative time delay of the first phototube during third harmonic time measurement; 2032 - the first phototube recording the time waveform and relative time delay during third harmonic time measurement. Detailed Implementation

[0024] The present invention will be further described below with reference to embodiments and accompanying drawings, but this should not be construed as limiting the scope of protection of the present invention.

[0025] Example:

[0026] Figure 1 This is a schematic diagram of a high-power laser beam delay measurement device according to the present invention. The device includes a clock reference 1, a high-speed oscilloscope 2, a first phototube 3, a second phototube 4, a repetition rate main laser system 5, and a third harmonic analog light 6. When performing time delay measurement by segment and wavelength, it is completed in two stages: relative time delay measurement of the fundamental frequency band and relative time delay measurement of the third harmonic band.

[0027] During the relative time delay measurement in the fundamental frequency band, the signal emitted by the clock reference 1 is ultimately connected to the first channel 201 of the high-speed oscilloscope 2 as an electrical signal, serving as a reference point for the fundamental frequency time delay. The output pulse of the repetition frequency main laser system 5 is received by the first phototube 3 before reaching the harmonic conversion module 7 after passing through the high-power laser system. The electrical pulse generated by the first phototube is connected to the second channel 202 of the high-speed oscilloscope. The first channel 201 or the second channel 202 of the oscilloscope is selected as the external trigger source of the oscilloscope. The delay of the waveform 2011 of the first channel 201 and the waveform 2021 of the second channel 202 of the oscilloscope after one trigger is recorded as Δt1.

[0028] During the relative time delay measurement in the third harmonic band, the third harmonic analog light 6 is incident in front of the harmonic conversion module 7, and converges to the target point after passing through the terminal optical components such as the harmonic conversion module 7. A second phototube 4 is placed at the target point, and the electrical pulse generated by the second phototube 4 is connected to the third channel 203 of the high-speed oscilloscope. The second channel 202 or the third channel 203 of the oscilloscope is selected as the external trigger source of the oscilloscope, and the delay of the waveform 2022 of the second channel 202 and the waveform 2032 of the third channel 203 of the oscilloscope after one trigger is recorded as Δt2.

[0029] Finally, the total delay is accumulated to determine the time delay of each beam from the repetition rate main laser system 5 to the target point relative to the clock reference 1 as Δ = Δt1 + Δt2 + δ, where δ is a fixed deviation, which is related to the first phototube 3, the second phototube 4 and their cables connected to the oscilloscope. For multiple laser beams, the same first phototube 3, the second phototube 4 and their cables connected to the oscilloscope are used. By repeating the above steps, the time delay of each beam to the target point relative to the clock reference can be measured separately.

[0030] The first phototube 3 must respond to both the fundamental frequency beam and the third harmonic beam.

[0031] The delay of the output pulse of the repetition rate master laser system relative to clock reference 1 does not change with time.

[0032] The third-harmonic simulated light 6 is coaxial with the third-harmonic beam generated by the main laser.

[0033] The third harmonic analog light 6 is generally based on a Q-switched laser that performs internal or external harmonic conversion to generate a repetitive pulse laser of several kilohertz, and usually exhibits many equally spaced small spikes.

[0034] The position and orientation of the first phototube 3 remain unchanged when measuring the relative time delay in the fundamental frequency band and the relative time delay in the third harmonic band.

[0035] The device includes a clock reference, a high-speed oscilloscope, a first phototube, a second phototube, a high-repetition-rate main laser system, and third-harmonic analog light. Time delay measurements are performed in segments and wavelengths, completed in two stages: relative time delay measurement in the fundamental frequency band and relative time delay measurement in the third harmonic band.

[0036] During the relative time delay measurement in the fundamental frequency band, the signal emitted by the clock reference is ultimately input to the first channel of the high-speed oscilloscope as an electrical signal, serving as a reference point for the fundamental frequency time delay. The output pulse of the repetition rate main laser system is received by the first phototube before reaching the harmonic conversion module after passing through the high-power laser system. The electrical pulse generated by the first phototube is input to the second channel of the high-speed oscilloscope. Either the first channel or the second channel of the oscilloscope is selected as the external trigger source for the oscilloscope, and the delay of the waveforms in the first and second channels of the oscilloscope after one trigger is recorded as Δt1.

[0037] During the relative time delay measurement at the third harmonic band, the third harmonic analog light is incident in front of the harmonic conversion module, and after passing through the terminal optical components such as the harmonic conversion module, it converges to the target point. A second photodiode is placed at the target point, and the electrical pulse generated by the second photodiode is connected to the third channel of the high-speed oscilloscope. The second or third channel of the oscilloscope is selected as the external trigger source of the oscilloscope, and the delay of the waveforms of the second and third channels of the oscilloscope after one trigger is recorded as Δt2.

[0038] Finally, the total delay is accumulated to determine the time delay of each beam from the repetition rate main laser system to the target point relative to the reference, which is Δ = Δt1 + Δt2 + δ, where δ is a fixed deviation that is related to the first phototube, the second phototube, and their cables connected to the oscilloscope. For multiple laser beams, the same first phototube, the second phototube, and their cables connected to the oscilloscope are used. By repeating the above steps, the time delay of each beam to the target point relative to the clock reference can be measured separately.

[0039] The first phototube must respond to both the fundamental frequency beam and the third harmonic beam.

[0040] The delay of the output pulse of the repetition rate master laser system relative to the clock reference does not change with time.

[0041] The third-harmonic simulated light is coaxial with the third-harmonic beam generated by the main laser.

[0042] The third harmonic analog light is generally based on a Q-switched laser that performs internal or external harmonic conversion to generate a repetitive pulse laser of several kilohertz, and usually exhibits many equally spaced small spikes.

[0043] The position and orientation of the first phototube remain unchanged when measuring the relative time delay in the fundamental frequency band and the relative time delay in the third harmonic band.

[0044] In actual operation, it is often unnecessary to focus on the absolute value of the delay of a particular beam reaching the target point relative to the clock reference. It is only necessary to ensure that the arrival times of multiple beams at the target point are consistent, or to adjust the delay relative to a particular beam. In this case, the fixed deviation δ related to factors such as the first phototube, the second phototube, and their cables connected to the oscilloscope can be ignored since the delay measurement is the same for each beam; only the sum of Δt1 and Δt2 needs to be considered.

[0045] If it is necessary to focus on the absolute value of the delay of a certain beam reaching the target point relative to the clock reference, the fixed deviation δ related to factors such as the first phototube, the second phototube, and the cables connecting them to the oscilloscope cannot be ignored. In this case, the absolute deviation can be calibrated in advance and deducted when calculating the absolute delay.

[0046] High-power laser devices typically require precise control over the arrival time of each beam when multiple beams need to reach the target simultaneously. High-power laser systems generally employ precise timing systems distributed to various functional modules, enabling the entire system to work collaboratively. This invention, without requiring additional components or emitting high-energy lasers, achieves precise measurement of the delay between the arrival time of each laser beam and a reference clock reference through the aforementioned process.

Claims

1. A high power laser beam inter-pulse delay measurement apparatus, characterized by, The clock reference, the high-speed oscilloscope, the first photoelectric tube, the second photoelectric tube, the main laser system with high repetition frequency and the triple-frequency analog light are included. In the relative time delay measurement in the fundamental frequency band, the signal emitted by the clock reference is connected to the first channel of the high-speed oscilloscope in the form of an electrical signal, and the pulse output by the main laser system with high repetition frequency is received by the first photoelectric tube and converted into an electrical pulse, which is connected to the second channel of the high-speed oscilloscope. In the relative time delay measurement in the triple-frequency band, the triple-frequency analog light is received by the second photoelectric tube after passing through the terminal optical element and is converted into an electrical pulse, which is connected to the third channel of the high-speed oscilloscope. By selecting different channels of the high-speed oscilloscope as the trigger source, the waveform delay amounts Δt1 and Δt2 in the fundamental frequency band and the triple-frequency band are recorded respectively, and the total delay Δ is determined, wherein Δ = Δt1 + Δt2 + δ, and δ is a fixed deviation.

2. The high power laser beam inter-delay measurement apparatus of claim 1, wherein, The first photoelectric tube is responsive to both the fundamental frequency light beam and the triple-frequency light, and the position and posture of the first photoelectric tube remain unchanged during the relative time delay measurement in the fundamental frequency band and the relative time delay measurement in the triple-frequency band.

3. The high power laser beam inter-delay measurement apparatus of claim 1, wherein, The triple-frequency analog light is coaxial with the triple-frequency light beam generated by the main laser.

4. The high power laser beam inter-delay measurement apparatus of claim 1, wherein, The triple-frequency analog light is a high-repetition-frequency pulsed laser generated by harmonic conversion based on a Q-switched laser, and has equally spaced small peaks.

5. The high power laser beam inter-delay measurement apparatus of any of claims 1-4, wherein, The position and posture of the first photoelectric tube remain unchanged during the relative time delay measurement in the fundamental frequency band and the relative time delay measurement in the triple-frequency band.

6. A method of measuring inter-beam delay of a high power laser beam, the method comprising: The method includes two stages, i.e., the relative time delay measurement in the fundamental frequency band and the relative delay measurement in the triple-frequency band. In the relative time delay measurement in the fundamental frequency band: The signal emitted by the clock reference is connected to the first channel of the high-speed oscilloscope in the form of an electrical signal, serving as the reference point of the time delay in the fundamental frequency band. The main laser output by the main laser system with high repetition frequency is received by the first photoelectric tube, and the electrical pulse generated by the first photoelectric tube is connected to the second channel of the high-speed oscilloscope. The first channel or the second channel of the high-speed oscilloscope is selected as the external trigger source, and the delay amount of the waveform in the first channel and the waveform in the second channel after triggering once is recorded as Δt1. In the relative delay measurement in the triple-frequency band: The triple-frequency analog light output by the triple-frequency analog light is converged to the target point after passing through the harmonic conversion module, and is received by the second photoelectric tube located at the target point, and the electrical pulse generated by the second photoelectric tube is connected to the third channel of the high-speed oscilloscope. The second channel or the third channel of the high-speed oscilloscope is selected as the external trigger source, and the delay amount of the waveform in the second channel and the waveform in the third channel after triggering once is recorded as Δt2. The time delay Δ of the moment when the main laser reaches the target point relative to the time of the clock reference is calculated, and the formula is as follows: Δ = Δt1 + Δt2 + δ In the formula, δ is a fixed deviation, which is related to the first photoelectric tube, the second photoelectric tube and the cable connected to the high-speed oscilloscope.

7. The high power laser beam time delay measurement method of claim 6, wherein, For multi-beam laser, repeat the above steps, respectively measure each light beam to the target point of the time relative to the clock reference delay amount.

8. The high power laser beam time delay measurement method of claim 6, wherein, The delay amount of the pulse output by the repetition frequency main laser system relative to the clock reference (1) does not change with time.

9. The high power laser beam time delay measurement method of claim 6, wherein, During measurement, the third harmonic analog light (6) is coaxial with the third harmonic light beam generated by the main laser.

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