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.
© 1994 Optical Society of America
Original Manuscript: February 4, 1993
Published: February 20, 1994
John B. Deaton and James W. Wagner, "Variable-cavity-length mode-locked Nd:YAG laser for noncontact generation and spectral control of narrow-band ultrasound," Appl. Opt. 33, 1051-1058 (1994)