Język
en
Treść
Single Beam phase reconstruction techniques are well established approaches for wavefront reconstructions in lens-less optical configurations. These approaches use a series of intensities captured at various defocus distances and rely on successful algorithms that use these data for the wave-field reconstruction. The usefulness of these methods has been demonstrated in the x-ray regime and the optical domain, i.e. in the area of life-sciences and the micro-optical metrology. However, the recovery of volume speckle fields has been made with varying degree of success, because conventional methods with equidistant measurement planes recover either only slowly varying (in case of deterministic paraxial methods) or fast varying wave-fields (in case of iterative wave-propagation based methods). A further critical aspect is the choice of the measurement planes, because specific sets of spatial frequencies may not be visible at the captured defocus planes. Usually this ill-posed problem is combated using regularization techniques giving increased computational effort with limited accuracy. This work reports an optimal single beam wave-field reconstruction with application to speckle field recovery for a wide range of spatial frequencies including both lower and higher spatial frequencies. The principle of this technique is based on cascading iterative and deterministic phase retrieval techniques as well as employing a plane selection strategy that ensures the support for all spatial frequencies for the given set of measurement planes. Reconstructions with this hybrid approach are fast, accurate, and unlike conventional methods do not require the use of regularization techniques. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
