  Simulation involves predicting responses of a physical system. In this
article, we simulate opto-acoustic signals generated in a three-dimensional
volume due to absorption of an optical pulse. A separable computational model
is developed that permits an order-of-magnitude improvement in computational
efficiency over a non-separable model. The simulated signals represent acoustic
waves, measured by a probe with a linear transducer array, in a rotated and
translated coordinate frame. Light is delivered by an optical source that moves
with the probe's frame. A spatio-temporal impulse response for rectangular
element transducer geometry is derived using a Green's function solution to the
acoustic wave equation. The approach permits fast and accurate simulation for a
probe with arbitrary trajectory. For a 3D volume of $n^3$ voxels, computation
is accelerated by a factor of $n$. This may potentially have application for
opto-acoustic imaging, where clinicians visualize structural and functional
features of biological tissue for assessment of cancer and other diseases.
