New optical techniques for crystal growth from fluids

Electronic speckle interferometry (ESPI) is a non-contact optical technique commonly devoted to the observation of microscopic deformation of material s due to stress or applied loads in real time with an accuracy of the order of a wavelength of light. This interferometric technique may also be appli ed to the observation of physical phenomena in transparent fluids, such as density and concentration gradients during crystal growth in aqueous soluti on or in gel. Differently from other more common interferometric techniques , e.g. holography, ESPI can operate under ordinary room light conditions an d may be arranged in a highly compact set-up. KDP crystal growth from solution has been studied with ESPI technique and d ata have been analysed in order to get information on solution dynamics and , furthermore, to prove the validity of this technique for crystal growth. The first results of this experience are described. (C) 2000 Elsevier Scien ce S.A. All rights reserved.