Seven-channel fabry-perot spectrum analyzer used in laser scattering measurements.

A high resolution seven-channel Fabry-Perot interferometer spectrum analyzer is described that was used in laser scattering experiments on a theta-pinch plasma where the spectral width to be measured was of the order of 1 A. The resolution of the system was 0.2 A and covered a wavelength interval of 1.4 A. The interferometer was of the pressure tuned type, using dry nitrogen gas, to center the laser radiation on any given channel for wavelength calibration of the system. The Fabry-Perot plates had to be antireflection coated for proper performance of the system. A complete profile of the Doppler broadened scattered light is obtained in a single discharge, and a typical spectral profile is shown.