Evaporographic and pyroelectric image recording for two-dimensional plasma interferometry in the far infrared

We report interferometric experiments which show that evaporography together with cw far infrared (FIR) sources in the 10-mW-power level is suited for two-dimensional FIR interferometry of stationary plasmas, while pyroelectric image recording in principle allows pulsed two-dimensional FIR interferometry with FIR pulse energies in the millijoule range. As an example, the electron density distribution in a carbon arc is determined interferometrically with a cw HCN laser (lambda = 337 μm). In addition, some specific problems of two-dimensional interferometry in the FIR are discussed