<title>Intracavity diagnostics of optical inhomogeneity</title>

Abstract

Direct measurements of radial optical inhomogeneity in long narrow elements (gas-discharge tubes, optical fibers, filamental crystals, etc.) entail some difficulties conditioned both by geometry and by littleness of optical properties absolute variations, especially critical in absorptive photothermospectroscopy. At the same time, in many such cases transverse optical inhomogeneity is close to lens-like type. It allows us to realize convenient and accurate procedure for measuring such inhomogeneity, disposing the inhomogeneous sample into the laser resonator and observing the inhomogeneity effect on the characteristics of generated radiation. This report presents general theoretic foundations for the proposed approach. Some variants of this procedure are analyzed and their advantages over common ones are shown. Experimental examination of the proposed method with an example of the He-Ne discharge element has shown its validity and usefulness.