ANALYTICAL ONE-DIMENSIONAL MODEL TO STUDY THE ULTRASONIC PRECURSOR GENERATED BY A LASER

We present an analytical one-dimensional model of the laser generation of ultrasound that takes the optical penetration effect into account. This model leads to a simple expression relating the full width at half maximum of the precursor to the product of the optical absorption coefficient by the longitudinal velocity, and establishes the conditions under which this expression is valid. The results of this model are compared to those provided by a more sophisticated semianalytical three-dimensional model and to experimental data obtained under various experimental conditions. The agreement is very good.