Active Modification of Reconstructed Wavefronts in Application of Digital Comparative Holography

Comparative digital holography (CDH) is a new interferometric method for comparison of the shape or deformation of two nominal identical objects with different micro structure. Besides the digital comparison in the computer the use of a spatial light modulator (SLM) allows not only the illumination of the object under investigation with the coherent mask of the master object but also the correction of misalignments of the test object and the adaptation of the local illumination intensity. In addition it is possible to mark the part of deviation of the object with the help of the SLM. These possibilities reduce the operating expenses and make the method suitable for the use in quality assurance at different locations. In the paper we describe the basic principle of CDH and the enhanced possibilities of using the SLM for active wavefront adaptation theoretically and experimentally, respectively.