We review different methods for giving phase contrast in optical microscopy. Microscopes based on scattering by the sample are usually partially coherent. We discuss how image formation in the partially coherent microscope can be analyzed using the Wigner distribution function. The Wigner function of the object transmission function is found to be physically related to the phase gradient of the object.

 

Colin Sheppard is Senior Scientist at the Italian Institute of Technology, in Genova, Italy. For 9 years he was Head of the Bioengineering Department in the National University of Singapore, and for 14 years Professor of Physics at the University of Sydney. He started researching on confocal microscopy in Oxford University, back in 1974, and launched the first commercial confocal instrument in 1982.

He has been the recipient of several awards, including Fellow International, Japan Society of Applied Physics (2013), Visiting Professor, Warsaw University of Technology, Poland (2013), Fellow, Optical Society of America (2012), Carl Zeiss Visiting Professor, Germany (2011-12), Erasmus Mundus Visiting Scholar, France (2011), Visiting Professor, EPFL, Switzerland (2008), Institute of Physics UK, Optics and Photonics Division Prize (2006), Bonhöffer Medal, Max Planck Society, Germany (2006), Fellow, Institute of Physics (2004), and Humboldt Research Award, Germany (2003).

His research interests include microscopy, including confocal and multiphoton microscopy, phase imaging, image reconstruction, diffraction, scattering, and beam & pulse propagation.