Non-destructive testing using electronic speckle pattern interferometry

At the Centre for Industrial and Engineering Optics a new Electronic Speckl e Pattern Interferometry (ESPI) system has been developed for non-destructi ve testing and strain measurements. The system uses a liquid crystal electr o-optical switch to change between the illumination geometries for sensitiv ity in two orthogonal directions. Two more liquid crystal devices provide p hase-shifting for automated analysis and the system is controlled by advanc ed software. There are no moving parts, which is an advantage in any ESPI s ystem, where mechanical stability is vital.