Experimental Investigations of Laser Micromachining of Nickel Using Thin Film Micro Thermocouples

Laser-material interactions during laser micromachining are extremely complicated. In order to improve the fundamental understanding of the laser micromachining process, it is essential to investigate the complex phenomena and mechanisms of the physical processes within and close to the region of the interaction. Moreover, C-type micro thin film thermocouples with a junction size of $2×2μm2$ were fabricated to increase the maximum operation temperature and spatial resolution of sensors. Surface temperature distribution around the laser spot was obtained in the range from $45μmto85μm$ away from the center of laser spot. The result showed that there was a steep gradient of temperature in the radial direction and a superheated area around the laser spot. Topographical characterizations of laser micromachining with various laser energy fluences were undertaken to correlate the resulting geometry changes with surface temperature measurements. Possible changes of surface chemical composition induced by the laser micromachining process, in particular, oxide formation, were also investigated around the laser spot.