  A coherent phase-contrast optical system has been designed and tested for
tomographic imaging of pressure fields from experimental transient acoustic
signals. The system is similar to the pulsed, central-order schlieren method,
but uses a Fourier filtering technique that images the actual acoustic pressure
field, where the former technique reconstructs only the absolute value of the
field. Simulations of the system are performed using a single-cycle sine-wave
acoustic pulse. Experimental images resulting from a broad-band Gaussian pulse
input to an underwater piezoceramic transducer array are presented. Relative
pressure field s are reconstructed in space over a series of times after the
source excitation. Theory and limitations of the phase contrast system are
discussed.
