Analysis of Optical Emission towards Optimisation of Femtosecond Laser Processing

Recent research and development on the femtosecond laser has shown that it is a powerful tool for high precision micromachining. However, femtosecond laser-material interaction is fast and complex due to its ultrashort pulse duration. As the laser-induced plasma possesses useful information to understand the physical mechanism of laser processing, we investigate the optical emission during femtosecond laser material processing. Laser-induced plasma spectra of brass, silicon and tin were captured using a fibre optic spectrometer. Key parameters of the plasma such as plasma temperature and electron density were estimated based on the spectral details. These results may serve as a necessary basis of further research into the development of on-line monitoring techniques for the optimisation of the femtosecond laser processing.