Application of multidirectional holographic interferometer (MHOI) to study crystal growth in solution and gel

Abstract

ABSTRACTMultidirectional HOlographic Interferometer (IvIHOl), a non-invasive diagnostic tool to monitor three-dimensional concentration fields during crystal growth from solution, is applied to study the diffusion fields near the monocrystals ofpotassium dihydrogen phosphate growing in gel and solution. In contrast with other existing holographic interferometers,MHOI uses optical fibers in six optical circuits, realising for the first time the hardware of an optical tomograph. Thesystem allows us to obtain the data required to get real 3D reconstruction of diffusion fields.Keywords: Holographic interferometry, crystal growth, solution growth, gel growth, KDP, optical tomography 1. INTRODUCTION The crystal growing in solution modifies the concentration of the solution around its faces. The so-called diffusion layer appears. Thickness of this layer in the presence of convection is about few hundreds of micrometers. In the case of convectionless conditions (gel, microgravity) the diffusion field extends few centimetres far from the crystal face. Theproperties of the diffusion layer are very important for understanding transport processes but they can also deliver, whencombined with surface examination methods, valuable information about the surface kinetics.1'2 Optical methods likeinterferometry and holographic interferometry 6-9