LASER BEAM PROPAGATION THROUGH THREE-DIMENSIONAL HIGH-ASPECT-RATIO MICROHOLES

The drilling of high-aspect-ratio microholes has very important applications in automotive, aerospace, electronics and other areas. However, this is difficult to realize with conventional mechanical machining or electrical discharge machining approaches. Laser ablation can potentially provide a good solution to this, but it also involves many technical difficulties. One of these is that the hole structure may act like a wave guide and affect the laser beam propagation. However, previous investigations on this important issue are very limited. In this paper, laser beam propagation through high-aspect-ratio microholes has been studied by solving the three-dimensional transient Maxwell's wave equation, and the important discoveries from the calculations are discussed.