Shock waves generated by rear- and front-side infrared(&lgr;=1.064 &mgr;m)laser irradiation of calcite were measured using time-resolved surface-plasmon resonance spectroscopy. The shock waves generated in the two cases are found to be distinctly different: Rear-side ablation gives rise to planar shock waves, while the front-side ablation is more nearly spherical. The observed differences are related to differing material-removal mechanisms at the two surfaces. ©1997 American Institute of Physics.