An improved optical resonator for measuring time-dependent electron densities

The performance of an optical resonator used for measuring time-dependent electron densities in the collapse phase of a Z pinch has been improved by the introduction of a simulated concentric mirror system, which reduces problems due to gradients in the refractive index inherent in the nonconcentric configuration, and by the introduction of a rotating quartz block, which modulates the resonator length, increasing the temporal resolution by a method analogous to the fractional-fringe techniques of conventional interferometry.