Optical fiber sensing measurement method of laser plasma shock wave mechanical effect

Abstract

The invention relates to an optical fiber sensing measurement method of a laser plasma shock wave mechanical effect. According to the measurement method, a high-power density and short pulse femtosecond laser is used for irradiating a target to generate a high-pressure plasma stock wave, and an optical fiber sensing signal demodulation system for on-line monitoring of a femtosecond laser plasma is set up by using an optical fiber F-P (Fabry-Perot) acoustic emission sensing probe. A time history of the shock wave is obtained by measuring acoustic frequency and intensity information of the laser plasma shock wave in the same position at different times, the spatial distribution of the shock wave is obtained by measuring the intensity information of a microplasma shock wave at the same time in different positions, and the temperature compensation is conducted by using an FBG (Fiber Bragg Grating) sensing technology and a differential structure to study the macromechanical effect of the femtosecond laser plasma shock wave. The method for measuring the laser plasma shock wave mechanical effect is high in spatial resolution, response speed and sensitivity, and the measurement accuracy can be improved.

Description

technical field [0001] The invention relates to the technical field of optical fiber sensing, in particular to an optical fiber sensing measurement method for the mechanical effect of laser plasma shock waves, which is mainly used for the measurement, analysis and processing of the mechanical effects of plasma shock waves generated by the interaction between laser and materials. Background technique [0002] When the laser irradiates the surface of the material, due to the absorption of the laser on the surface of the material, the surface temperature of the material continues to rise. When the surface temperature of the material reaches the vaporization temperature, vaporization will occur. If the ablation steam particles continue to absorb laser energy, the steam absorbs through inverse bremsstrahlung, causing a large amount of laser energy to be deposited, and the temperature of the steam continues to rise, which will eventually lead to ionization of steam molecules, formi...

AI Technical Summary

Problems solved by technology

On the one hand, in terms of the ablation mechanism of the target, such as the dual-temperature model and the modified dual-temperature model, there is a lack of a theoretical model that truly describes the dynamics of the femtosecond laser plasma shock wave; on the other hand, the technology for analyzing laser plasma In terms of means, such as ultra-fast spectroscopy technology, optical multi-channel analyzer and other technical means, however, these technical means are mainly based on molecular spectroscopy, which cannot comprehensively monitor the dynamic characteristics and mechanical effects of plasma shock waves; on the other hand, In the analysis of the mechanism of the mechanical effect of the laser plasma shock wave and related detection methods, such as the use of piezoelectric sensing, suspension pendulum and optical interference and other technical methods, the combination of the suspension pendulum method and the photoelectric velocimetry method, a method based on light deflection However, the above-mentioned measurement method still has technical limitations, such as the optical path of the optical interferometer is complicated, the preparation is difficult, the measurement is easily disturbed by external factors, the stability is poor, the energy fluctuation of the light source, transmission and coupling loss and other problems , the measurement accuracy is limited, etc., there are difficulties in the measurement of femtosecond laser micro-plasma shock waves

[0004] In short, the above technical means have certain limitations in the study of the mechanical effects of laser plasma shock waves, and it is necessary to explore a new technology means and method with high spatial resolution, response rate and sensitivity

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