title: Variable-cavity-length mode-locked Nd:YAG laser for noncontact generation and spectral control of narrow-band ultrasound.
abstract: A passively mode-locked, flash-lamp-pumped long-cavity Nd:YAG laser was developed with a cavity length that was variable in discrete increments from approximately 11 to 60 m, permitting adjustment of the mode-locked pulse repetition frequency over a range from 13 to 2.5 MHz. Multiple-pulse acoustic signals were generated with this laser in an aluminum sample and remotely detected by a path-stabilized Michelson interferometer. The energy in the multiple-pulse acoustic signal was confined to a considerably reduced spectral range compared with that in a single pulse. Successful laser generation of spectrally selective narrow-band ultrasound presents new opportunities to integrate advanced signal-processing strategies with interferometric detection to enhance the sensitivity of laser ultrasonics for industrial applications.
authors.forename: J B
authors.initials: JB
authors.lastname: Deaton
authors.forename: J W
authors.initials: JW
authors.lastname: Wagner