ORVIS: optically recording velocity interferometer system. Theory of operation and data-reduction techniques

An optically recording velocity interferometer system (ORVIS) has been developed to measure particle velocity histories in shock wave experiments on condensed matter. The interferometer fringe motion is recorded with a high speed electronic streak camera, rather than with photomultiplier tubes and oscilloscopes as in previous interferometry systems. With this approach, the particle velocity of a witness foil in a detonation wave experiment was measured with 300-ps time resolution. We believe that 20-ps time resolution can be achieved with this technique which would represent an improvement of two orders of magnitude over previous measurement techniques. The optical design is described along with techniques for operation. The data reduction system is described including a computer program for digitizing and analyzing the recorded images.