Practical Applications Of Femtosecond Laser Micromachining

Femtosecond laser micromachining has many potential applications due to its advantages, such as limited heat-affected zone and more precision machining. This thesis mainly focuses on the practical applications of femtosecond laser micromachining. The relationship between the characteristics of femtosecond laser parameters, machining speed and the cutting width is discussed. The diffraction-limited cutting on the gold films and silver films is obtained. The fabrication of transmission gratings into the transparent materials and the machining of energetic materials substitute are studied.The fabrication of transmission gratings with the grating constant of 2.5μm and 5μm is studied in ZK6 and LaF2 glasses at the machining speed of 400μm/s by using femtoscond laser with the peak intensity of 2.7×10¹³W/cm², and the diffraction patterns of the grating are presented with a semiconductors laser at 650 nm. At the machining speed of 2.5mm/s,the array holes are drilled in ZK6 and LaF2 glasses with the peak intensity of 2.7×10¹³W/cm².The dependence of ablation rate with laser intensity and the number of laser pulses is studied, and found that the depth of the ablation is increasing almost linearly with the laser intensity, and the ablation rate decreases with the increasing the number of the applied laser pulses while the laser ablation fluence keeps invariable. The diffraction-limited machining on the gold films and silver films is obtained with the laser peak intensity of 8.1×10¹²W/cm².The grooves with the width of 2.5μm are cut on the gold films and silver films at the machining speed of 400μm/s with the peak intensity of 8.1×10¹²W/cm².The results suggest that precise micromachining can be achieved by controlling the intensity. Preliminary cutting and drilling on energetic materials substitute is studied. At the peak power from 3.3×10⁹W to 1.3×10¹⁰W, the cutting width of 150μm is obtained at the machining speed from 0.1mm/s to 2mm/s, which lay the foundation of future research.