Acoustic chaos and sonic infrared imaging

We describe a quasichaotic mechanism for the generation of complex vibrations from the application of a 450 ms, 40 kHz excitation coupled nonlinearly to a sample under inspection by means of sonic infrared (SIR) imaging. Monitoring the sample vibration by means of a laser vibrometer, we find that the vibration switches from the fundamental and harmonics to several series of frequencies that are rational fractions of the fundamental driving frequency. The transition to this quasichaotic behavior is important in obtaining high-quality SIR images. (C) 2002 American Institute of Physics.