A simplified cavity analysis for estimating energy coupling during laser ablation and drilling of solids – theory

A radiative cavity analysis is developed to estimate the change in laser energy coupling with a solid opaque target as a function of the cavity shape and size, and the heat transfer in a target. The approach of the analysis is to examine the departure in the net energy absorbed by a target due to the formation of a cavity, from that absorbed by a flat surface. The development of a general departure function, f, is presented, complete with the assumptions made and their implications on the resulting analysis. A specific f for a typical laser ablation process and common cavity geometry is also given in algebraic form. The meaning of the terms contained within f are discussed with respect to laser energy coupling in solids, and the range of validity of the theory is examined. q1998 Elsevier Science B.V.