Real-time characterization of acoustic modes of polyimide thin-film coatings using impulsive stimulated thermal scattering

Abstract

A method for real-time optical characterization of thin-film acoustic modes is demonstrated. Pseudo-Rayleigh acoustic waves of thin (∼1 μm) polyimide films attached to silicon substrates are optically excited and monitored in real time as they propagate. The results can be used to determine mechanical properties (elastic moduli) and to guide thin-film fabrication and curing procedures.