Improved system and method for detecting composition of material by LIBS (Laser Induced Breakdown Spectroscopy) with high signal and noise ratio and low detection limit

Abstract

The invention discloses an improved system and an improved method for detecting the composition of a material by LIBS (Laser Induced Breakdown Spectroscopy) with high signal and noise ratio and low detection limit. The improved system combines femtosecond pre-ablation double-pulse LIBS and polarized resolution LIBS and comprises a femtosecond-pulse laser with a fixed wavelength, a super-continuum spectrum femtosecond-pulse laser, a light filter, a reflecting mirror placed by 45 degrees, a beam combining mirror, a beam expanding mirror, a telescope, a beam splitting mirror placed by 45 degrees, a polarization mirror with an adjustable polarization angle, an optical-fiber coupling mirror, an optical-fiber interface, an ICCD (Intensified Charge Coupled Device) spectrograph and a computer. The system disclosed by the invention has the advantages that double pulses are used for exciting the LIBS and light signals received are transmitted into the spectrograph by the polarization mirror, so that the detection limit of elements can be effectively reduced, the signal and noise ratio can be increased, the accuracy and the stability of detection can be improved, molecular spectrum and the atomic spectrum also can be detected simultaneously and more accurate information of the composition of the material can be provided.

Description

technical field [0001] The present invention relates to a laser spectrum detection system, in particular to a combination of femtosecond Pre-Ablative Double-Pulse Laser-Induced Breakdown Spectroscopy (Femtosecond Pre-Ablative Double-Pulse Laser-Induced Breakdown Spectroscopy, fs-PA-DP-LIBS for short) and A detection system and method for Polarization Resolved Laser-Induced Breakdown Spectroscopy (PR-LIBS for short). Background technique [0002] Laser-induced breakdown spectroscopy (LIBS) detection technology uses high-energy short-pulse-width pulsed lasers to irradiate the surface of the object to be measured through focusing, and obtains laser pulses with extremely high energy density at the focus, so that the surface of the irradiated target is ablated and evaporated. , ionization, forming a plasma spark with high temperature, high pressure, and high electron density, which radiates a spectrum including characteristic atoms and ion lines, which can be used to detect the c...

AI Technical Summary

Problems solved by technology

[0006] In the published patent document (application number: 201210246338) of laser-induced breakdown spectroscopy measurement technology based on double-pulse and polarization resolution, reheating double-pulse LIBS is adopted, which can be used to improve detection accuracy, but reheating double-pulse LIBS The influence of impurities on the surface of the measured substance on the LIBS spectral signal cannot be removed, and it is difficult to further improve the measurement accuracy. At the same time, the traditional LIBS cannot further measure the molecular composition of the substance. In order to further improve the detection accuracy of LIBS, this patent proposes a combination Material composition detection system and detection method of femtosecond pre-ablation double-pulse LIBS and polarization-resolved LIBS, this method combines femtosecond pre-ablation double-pulse LIBS and polarization-resolved LIBS, and adjusts the time interval and polarization of double pulses through computer control The polarization angle of the plate, by changing the passband range of a specific wavelength bandpass filter, changing the wavelength of one of the laser beams, achieves the purpose of reducing the detection limit, improving detection accuracy, improving signal-to-noise ratio, and improving stability. With the application of femtosecond laser pulses, the molecular spectrum and atomic spectrum can be detected simultaneously, and more accurate material composition information can be obtained

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