Efficient Pocketing Simulation Model for Solid State Laser Micromachining and its Application to a Sol-gel Material

Laser ablation using diode pumped solid state lasers shows great potential for a wide range of micromachining applications. We have been using a frequency quadrupled Nd:VO4 laser (266 nm wavelength), with a pulse duration < 30 ns, to ablate a sol-gel Ormocer material. With a pulse energy of around 20 μJ, and a focal spot of the order of 10 μm diameter, single pulses were found to produce craters a few microns in depth and ~10 μm in diameter. A study of the variation of the crater profile with pulse energy and angle of incidence to the surface has enabled the development of an efficient method to simulate the ablation for a series of consecutive shots constituting a toolpath. Multiple pulses with varying degrees of overlap were simulated, and compared with experiment. Results show that the model accurately predicts the profiles of trenches and pocketed surfaces given parameters obtained from a single crater machined at normal incidence. The “self calibrating” feature of our approach significantly reduces the number of input parameters required for adequate simulations. In particular, it does not require knowledge of the beam profile or material ablation curve. The simplicity and practicality of the method make it promising for use in an industrial environment.