Spectroscopical Measurements of Ablation Plasma Generated by an Excimer Laser from Functionally Graded Materials

Functionally graded materials (FGMs) are drawing attention in the fields of industrial applications. For industrial applications, FGMs require reprocessing, such as cutting and drilling. It is generally difficult to reprocess FGMs. Therefore, excimer laser processing that enables microprocessing has been made available. When the FGM is exposed to a laser beam, ablation plasma is generated. The mechanism of generating the ablation plasma, which differs for each material, influences the accuracy of production, but this has not been investigated sufficiently. The purpose of this study is to analyze the mechanism of ablation plasma generation and to achieve precise microprocessing and surface treatment methods for FGMs by controlling the plasma generation. This paper reports on the characteristics of the electron temperature in ablation plasma. The laser used in this experiment was an ultraviolet pulse excimer laser with a wavelength of 308 nm, a maximum pulse energy of 500 mJ and a pulse duration of 30 ns. The electron temperature dependence of the ablation plasma plumes on the ceramic-metal content of FGMs is observed.