Interferometrische Untersuchung der Deformation von Laserstäben während des Pumpvorganges

Abstract

The elongation of neodymium-glass laser-rods (LG 52 and LG 55 of Schott u. Gen., Mainz), the curvature and the tilting of their end surfaces have been measured by means of a MICHELSON-interferometer, a rotating-drum-camera and a laser illuminating the interferometer with short, isolated “spikes” during the pumping pulse of the rod. The pumping arrangements used for the tested rods are an elliptical cylinder and a rotational ellipsoid. A linear dependence of the observed deformation from the absorbed pumping energy is observed for this four-level material, so that the elongation of the rod and the curvature and the tilting angle of the surfaces can be expressed in terms of the pumping energy. The deformation measured in the elliptical cylinder pumping arrangement is compared with the calculated density of the absorbed energy within a laser rod illuminated by such an elliptical mirror. The main features of the observations are represented by this calculation.