Multiple-Beam Interferometry

An optical interferometer is described in which spatial and temporal resolution of the plasma density are achieved simultaneously, thus circumventing a limitation of conventional interferometers. The instrument consists of a Twyman-Green interferometer illuminated by a CW He-Ne laser. The technique has proven to be particularly applicable to plasma events that lack reproducibility. An additional advantage is that the interferometer is easily adapted to real-time displays of the plasma density profile utilizing an automated process.