A semi-empirical method to determine the undercooling-velocity relationship
for laser induced melting is presented. The technique uses measurements of
melt depth versus time to control numerical simulations, resulting in a map
of the interface temperature as a function of time, and consequently as a
function of the interface velocity. The results are independent of any model
for the velocity-undercooling relationship. Results of the technique on
simulated and experimental melt depth data are presented. Transient
conductance data on 28 nanosecond 694 nm laser irradiation of silicon
indicate an undercooling-velocity slope of 17±3 K/(m/sec) near the melting
point. Picosecond optical transmission data show a much smaller slope.