Radiation-Induced Sound.

Radiation-induced-sound experiments were conducted with one to four 10.6 micrometer CO2 laser pulses. These experiments were conducted to demonstrate the ability to control the acoustic energy spectral density. The acoustic signatures were Fourier analyzed to obtain the energy spectral density. The results show that the ratio of the width of a peak in the spectrum to the fundamental frequency scales approximately as the inverse of the number of pulses. This scaling does not hold if the pulses are not evenly spaced or not even in amplitude. Theoretical modeling formulated scaling laws relating laser parameters to acoustic parameters of the generated signatures. Theoretical predictions were also made of the change in amplitude and shape of the broadband signals due to frequency-dependent absorption as a function of propagation distance. Author