A HIGH-RESOLUTION REAL-TIME TEMPORAL HETERODYNE INTERFEROMETER FOR REFRACTIVE-INDEX TOPOGRAPHY

A Mach-Zehnder interferometer for two-dimensional refractive index top ography is presented which utilizes the temporal heterodyne technique. High scanning rates and excellent phase resolutions are obtained usin g an image dissector camera and a lock-in amplifier. The setup is appl ied for investigation of the photorefractive effect. A macroscopic lig ht pattern is recorded and thermally fixed in iron-doped LiNbO3. The e volution of the refractive index pattern during development by homogen eous illumination is observed with the interferometer. The measured re fractive index profiles are in good agreement with the results of comp uter simulations. (C) 1997 Elsevier Science B.V.