Development of spectroscopic measurement techniques for laser processing

Miyabe, Masabumi; Iwata, Yoshihiro; Terabayashi, Ryohei*; Hasegawa, Shuichi*

no journal, , 

Various laser processing techniques such as laser cutting and laser decontamination are being considered for use in decommissioning. We are developing emission and absorption spectroscopy techniques to detect contamination in the work environment during laser processing and to evaluate the decontamination efficiency of materials in a rapid and non-contact manner. Atomic species ejected from the surface of a material irradiated by an intense laser beam absorb the optical energy of the irradiating laser via inverse bremsstrahlung process and rapidly grow into laser plasma. Therefore, the characteristics of the resulting laser plasma are strongly affected by the pulse length of the ablation laser. In previous studies. However, little was known about the emission and absorption spectra of laser irradiation of about 10 ms, which is often used in laser processing. Therefore, in this study, we measured the emission spectra of various materials such as zirconia using a QCW fiber laser with a pulse length of about 10 ms. The resultant emission spectra are very similar to the characteristics previously reported for long-pulse lasers, and basic spectral characteristics were clarified, such as the greater contribution of molecular emission compared to atomic emission, and the stronger the emission intensity for elements that are more likely to undergo combustion reactions in air. This provided basic data for spectroscopic measurements for laser processing.