Quantitative evaluation of two-dimensional dynamic deformations using digital holography

An optical system for the parallel evaluation of in- and out-of-plane dynamical deformations will be described. A double pulse laser with pulse separation in the microsecond range is used for the investigations. Two separate interferograms of an object under test, in its undeformed and deformed state, are recorded in a few microseconds. The object is illuminated from two different directions and imaged onto a CCD sensor. This produces two sensitivity vectors. The reference beams have different directions in order to produce two directional spatial carriers. The Fourier method is used for quantitative evaluation, and the measurements along different sensitivity vectors are separated in the Fourier domain. The phases of the two interferograms are obtained from the complex amplitudes and the two dimensional deformation is calculated from the phases. Experimental results are presented.     

Computer-generated holograms from 3D-objects written on twisted-nematic liquid crystal displays

In order to optimize computer-generated holograms (CGHs) for three-dimensional objects, an extension of the well known Gerchberg-Saxton algorithm is used. Optical reconstructions using an electrically addressed twisted-nematic liquid crystal display are presented. For arbitrary CGHs, reconstructing 3D-objects, we will discuss the problems and solutions associated with periodic replication of holograms.