Chinese Optics, Volume. 17, Issue 2, 253(2024)

Study and analysis of self-absorption-free laser-induced breakdown spectroscopy with high-repetition rate acousto-optic gating

Fei CHEN1,2, Shu-qing WANG3, Nian-kai CHENG4, Wan-fei ZHANG5, Yan ZHANG6, Jia-hui LIANG1,2, Lei ZHANG1,2、*, Gang WANG5, Xiao-fei MA5, Zhen-rong LIU5, Xue-bin LUO5, Ze-fu YE7, Zhu-jun ZHU7, Wang-bao YIN1,2、*, Lian-tuan XIAO1,2, and Suo-tang JIA1,2
Author Affiliations
  • 1State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China
  • 2Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
  • 3National Energy R & D Center of Petroleum Refining Technology (RIPP, SINOPEC), Beijing 100083, China
  • 4China Academy of Ordnance Science, Beijing 100089, China
  • 5Shanxi Xinhua Chemical Defense Equipment Research Institute Co., Ltd., Taiyuan 030041, China
  • 6School of Optoelectronic Engineering, Xi’an Technological University, Xi’an 710021, China
  • 7Shanxi Gemeng US-China Clean Energy R & D Center Co., Ltd, Taiyuan 030032, China
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    To eliminate the self-absorption effect in laser-induced breakdown spectroscopy (LIBS) and improve the accuracy of elemental quantitative analysis, the device of self-absorption free laser-induced breakdown spectroscopy (SAF-LIBS) technology needs to be miniaturized to meet the requirement of convenient elemental analysis in industry. This paper presents a novel quantitative analysis technique, the high repetition rate acousto-optic gated SAF-LIBS method. To enhance integral spectral intensity, a high repetition rate laser is used to produce quasi-continuous plasmas. In addition, an AOM (acousto-optic modulator) serves as an optical gating switch, enabling the use of a compact charge-coupled device (CCD) spectrometer and AOM instead of the intensified charge coupled device (ICCD) and medium step grating spectrometer in conventional large-scale SAF-LIBS devices. The results in a self-absorption-free system that is less bulky and less expensive. After optimizing the system parameters, the quantitative analysis and prediction of the Al element in the sample was achieved. Experimental results show that plasma characteristics are impacted by the laser repetition rate, which affects the intensity of spectral signal. The doublet intensity of Al I 394.4 nm and Al I 396.15 nm is enhanced and then diminished at a laser repetition rate ranging from 1 kHz to 50 kHz, with the optimal repetition rate identified as being 10 kHz. The doublet line intensity ratios of Al decrease with delay time under different fiber collection angles. The highest signal-to-noise ratio is achieved at an angle of 45°, while the optimal optically thin time tot is 426 ns at a certain integration time. Al is quantitatively analyzed and predicted at a laser repetition rate of 10 kHz, fiber collection angle of 45°, and delay time of 400 ns. The experimental results show that the calibration curve linearity of R2 is 0.982 and an average absolute prediction error of aluminum is reduced from 0.8% of single LIBS to 0.18%, which is equivalent to that of traditional SAF-LIBS. Additionally, the high repetition rate acousto-optic gating SAF-LIBS not only effectively eliminates continuous background radiation and broadens spectral lines in optically thick plasma, but also offers the advantages of miniaturization, low cost, convenience, and reliability. Therefore, this study plays a significant role in advancing SAF-LIBS technology from laboratory testing to industrial applications.

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    Fei CHEN, Shu-qing WANG, Nian-kai CHENG, Wan-fei ZHANG, Yan ZHANG, Jia-hui LIANG, Lei ZHANG, Gang WANG, Xiao-fei MA, Zhen-rong LIU, Xue-bin LUO, Ze-fu YE, Zhu-jun ZHU, Wang-bao YIN, Lian-tuan XIAO, Suo-tang JIA. Study and analysis of self-absorption-free laser-induced breakdown spectroscopy with high-repetition rate acousto-optic gating[J]. Chinese Optics, 2024, 17(2): 253

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    Paper Information

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    Received: Aug. 23, 2023

    Accepted: --

    Published Online: Apr. 15, 2024

    The Author Email:

    DOI:10.37188/CO.2023-0147

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