Probing of ultrasonic pulses by multidirectional light

An acousto-optical reconstruction method for acoustic signals using multidirectional light diffraction by finite amplitude ultrasonic pulses is presented. When crossing the ultrasonic field, the far field diffracted laser light intensity of an incident convergent lightbeam becomes modulated in time. It is found that for special conditions, concerning direction of observation, ultrasonic frequency, power level and interaction length, the modulated light intensity is almost an exact copy of the diffracting acoustic pulse. Reconstruction can be completed by applying a fast Fourier transform (FFT) routine. Examples are provided and applications of this optical probing technique are suggested.