Holographic interferometry and moire deflectometry for visualization and analysis of low-gravity experiments on laser materials processing

The use of two optical diagnostic techniques for the visualization of low-gravity experiments is described. The analysis of requirements relevant to the low-gravity environment led to the choice of real-time holographic interferometry and moire deflectometry as suitable optical visualization techniques. An optical setup designed to operate in the KC-135 aircraft is described. An interactive fringe analysis system is also presented. Fringe center lines are extracted using a special onedimensional algorithm. The reconstruction of physical parameters from axisymmetrical objects is achieved using direct and inverse Abel transforms on moire and interferometric fringe fields. The applicability of the optical diagnostic techniques to the visualization of laser processing with liquids and solids in a low-gravity environment is demonstrated and experimental results on laser beam interaction with plastic, quartz, and water are presented.