Modulated laser array sources for generation of narrowband and directed ultrasound

Patterned illuminating sources and appropriate time modulation may be used to enhance certain features of laser-generated acoustic waves in time or frequency as a function of direction. Steerable, narrowband, “toneburst” ultrasonic signals have been generated from a single laser pulse which was spatially modulated by transmission through a lenticular array. In addition, narrowband toneburst ultrasonic waves have been generated from a mode-locked laser pulse train providing spectral narrowing of the laser-ultrasonic signal. Both temporal and spatial modulation of the laser pulse improve the signal-to-noise ratio for laser ultrasonics.