New progress in industrial online testing research of Shenyang Institute of Automation, Chinese Academy of Sciences

[ Instrument Network Instrument Development ] Recently, the research team of Shenyang Institute of Automation, Chinese Academy of Sciences proposed a laser-induced breakdown spectroscopy spectral line intensity correction method based on image feedback, which realized the suppression and compensation of spectral signal fluctuations, and applied it. In the field of industrial online inspection, the online measurement stability is significantly improved. The research-related series of results were published in top journals in the field of spectroscopy and analytical chemistry, and were widely discussed at the 3rd Asian Laser-induced Breakdown Spectroscopy Workshop (ASLIBS2019).

Structure and calibration results

Laser-induced breakdown spectroscopy (LIBS) technology has become an important technology for on-site inspection of process industry because of its advantages of in-situ, on-line and simultaneous analysis of various elemental compositions. However, the problem that the stability of the LIBS spectrum is difficult to guarantee is a key issue that restricts the application of the technology. In the laboratory environment, LIBS spectral stability can be improved by sample pretreatment, physical constraints, and experimental condition control. However, in complex and harsh industrial on-site testing environments, due to fluctuations in experimental conditions, the inability of samples to be pretreated, and the limitations of physical constraints, the resulting LIBS spectra fluctuate greatly, seriously affecting the measurement. accuracy.

Laser-induced plasma is the source of the LIBS spectrum, and its change in morphology and intensity is the direct cause of spectral fluctuations in LIBS. The research team introduced the laser-induced plasma image into the LIBS spectral stability correction modeling. By synchronously acquiring the LIBS spectrum and the corresponding plasma image, the difference of the plasma image features was used as the feedback signal to the corresponding characteristic line intensity. Compensation and correction, the corrected LIBS characteristic line stability is greatly improved, providing more reliable spectral data for LIBS online detection applications.

In recent years, the LIBS team of Shenyang Institute of Automation has systematically studied plasma image feedback correction LIBS spectroscopy, and the results obtained are published in international journals such as Analytical Chemistry and Journal of Analytical Atomic Spectrometry. At present, the corresponding subsystem has been added to the LIBS online component analyzer in the national key research and development plan - the development and application of industrial process online analytical detectors. The specific method has been applied in the online analysis of key elements of phosphate rock slurry.