PHASE-SHIFTING HOLOGRAPHIC DOUBLE-EXPOSURE INTERFEROMETRY WITH FAST PHOTOREFRACTIVE CRYSTALS

A technique for quasi real-time holographic interferometry with reflec tion type objects is presented. It is based on fast sequences of holog raphic double exposure interferograms recorded in sillenite-type photo refractive BTO crystals. The application of the phase shifting method for automatic quantitative evaluation of the obtained interferograms u nder the special constraint of short storage times in fast photorefrac tive crystals is investigated. Approaches to overcome this difficulty by applying a time dependent external electric field are discussed. Ex perimental results for dynamic analysis of reflecting type objects are presented.