Pressure waves can be generated in biological tissues by pulsed lasers which deposit optical energy in absorbing structures such as blood vessels. Arrays of acoustic detectors on a tissue surface can sense the arrival of such waves. Analysis of the time-resolved signals can be used to reconstruct the 3-D distribution of the absorbing structures.
In this report, a computer simulation was developed (see code listed on slide 4) to predict the time-resolved spatial distribution of pressure in a tissue in response to a pulse laser beam. In particular, the temporal history of pressure generated in a sphere of uniform energy deposition was calculated to illustrate the calibration of the computation. The temporal histories of pressures generated by a flat-field beam and a Gaussian-profile beam are also presented. The results show that the sharp edge of the flat-field beam yields tensile pressure wave and the pressure pattern is significantly different than the pressures produced by the smoother Gaussia-profile beam.
The computer simulation is a very simple computation that is a valuable tool for predicting expected experimental results, and may be used in a reconstruction algorithm.