<title>Automatic numerical processing of interferometric transonic flow measurements</title>

Abstract

We report on the application of holographic measuring techniques to various inverse scattering and tomographic imaging applications. The common feature in these applications is that the total transmitted field, when an object is illuminated by coherent radiation, is composed of the coherent sum of the incident wave and the scattered wave, forming in essence a Gabor hologram of the scattered wave and preserving its phase and amplitude. The object can then be reconstructed from the complex scattered field if the phase and amplitude information are extracted from the hologram. We discuss several methods for image reconstruction from the measured holograms. One such method is direct backpropagation, which is useful in multiview tomographic imaging of 3D objects, such as in optical diffraction tomography. Other methods discussed involve the use of iterative and non-iterative algorithms to retrieve phase information from the hologram(s) and other a priori information. These methods are also applicable to twin-image elimination in Gabor holography and to wavefront sensing. We present computer simulation and experimental results of using holograms in tomographic imaging and inverse scattering using several of these methods.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.