Study on Femtosecond Laser Stealth Cutting Technology of Quartz

In order to obtain high quality quartz section, a femtosecond laser system with wavelength of 1030nm, repetition frequency of 200KHz and pulse width of 290fs was used to study the stealth-cutting technology of fixed-focus scanning and variable-focus scanning for quartz wafer. The effects of single pulse energy, scanning times, defocusing amount and each downshifting distance of focus on the section of quartz wafer were investigated. Experimental results show that crack surface roughness can reach 46.35nm when the repetition rate is 20KHz, scanning speed is 2mm/s, single pulse energy is 50µJ and defocusing quantity is 0. In the variable focus scanning, the proportion of ablation zone gradually smaller with the increase of the downward shift of the focus. When the repetition frequency is 200KHz, the scanning speed is 4mm/s, the single pulse energy is 50µJ, and the focus is moved down by 5µm each time, the surface roughness of the fracture surface can reach 39.653 nm.