A Portable Electronic Speckle Pattern Interferometer with Integrated Topometric Surface Analysis

Electronic Speckle Pattern Interferometry (ESPI) is a well-proven tool for detection of sub-micrometer surface movements to indicate and localize material defects and elasticity properties. A portable ESPI measuring system for non-destructive testing is presented which has been optimized for mobile operation in the field of cultural heritage protection. By splitting the ESPI set-up into two separate units for illumination and monitoring linked by an optical fiber a very flexible usage of the set-up in different environments and for various applications is achieved. The image processing component is based on a digital camera interface standard and allows the unit to be controlled by a notebook computer. Various camera types can be used without the need to adapt hardware and software components. Furthermore, an additional camera can be integrated to perform photogrammetric calculations of 3D surface coordinates of the object under investigations which opens up the possibility to take into account a spatially varying sensitivity vector of the interferometric measurement. Results of characterisation measurements as well as applications in the analysis of artworks are presented.