Robert W. Schoonover

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This article maybe used for research, teaching and private study purposes. Any substantial or systematic reproduction, redistribution , reselling , loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents(More)
Correlation dependent, propagation-induced shifts in the generalized spectra of cyclostationary, random fields are predicted. This result generalizes the Wolf shift for stationary fields and is applicable to periodic trains of fast pulses such as might be generated in comb spectroscopy or other mode-locked pulsed systems. Examples illustrate these shifts(More)
Experimental observations of recently predicted correlation-dependent, propagation-induced changes in the spectrum and cross-spectra of a cyclostationary field are reported. An acoustic Young's experiment was conducted in which sources were driven by stationary signals modified by a square wave to make the process cyclostationary. The degree of correlation(More)
Diffraction and interferometry with fast pulses are analyzed for the case that the fields are partially correlated in time and in space. This generalizes a previous work [Schoonover, J. Mod. Opt.55, 1541(2008)], where only the temporal correlations of pulsed fields were considered in a Young's interferometer. The meaning of the interferograms is addressed(More)
The state of polarization of strongly focused, radially polarized electromagnetic fields is examined. It is found that several types of polarization singularities exist. Their relationship is investigated, and it is demonstrated that on smoothly varying a system parameter, such as the aperture angle of the lens, different polarization singularities can(More)
Optoacoustic tomography (OAT), also known as photoacoustic tomography, is an emerging computed biomedical imaging modality that exploits optical contrast and ultrasonic detection principles. Iterative image reconstruction algorithms that are based on discrete imaging models are actively being developed for OAT due to their ability to improve image quality(More)
A method is described which elucidates propagation of an electromagnetic field generated by a stochastic, electromagnetic source within the short wavelength limit. The results can be used to determine statistical properties of fields using ray tracing methods. A method is described which elucidates propagation of an electromagnetic field generated by a(More)
We present a detailed analysis of the structure of strongly focused, radially polarized electromagnetic fields. The existence of phase singularities of the two components of the electric field is demonstrated. Two different mechanisms to obtain creation or annihilation of these phase singularities are discussed. These are changing the aperture angle of the(More)
Photoacoustic computed tomography (PACT) is a rapidly emerging bioimaging modality that seeks to reconstruct an estimate of the absorbed optical energy density within an object. Conventional PACT image reconstruction methods assume a constant speed-of-sound (SOS), which can result in image artifacts when acoustic aberrations are significant. It has been(More)
Despite the extensive use of polycapillary x-ray optics for focusing and collimating applications, there remains a significant need for characterization of the coherence properties of the output wavefield. In this work, we present the first quantitative computational method for calculation of the spatial coherence effects of polycapillary x-ray optical(More)
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