The 3-dimensional shape of the processing surface can be reconstructed for typical laser applications like cutting, welding, drilling and hardening. In this paper laser beam cutting of stainless steel was investigated. The cutting front was reconstructed with high spatial and temporal resolution, taking benefit of the polarization dependence of the thermal emission. The reconstruction made it possible to resolve and measure structures, moving downwards at the cut front. The velocity was investigated with 75 000 frames per second and the resolution of the cutting front of 61 x 155 pixel. The velocity of the moving structures found to be approximately 10 m/s.