Method for observing phase objects without halos or directional shadows.

ABSTRACT

A new microscopy method for observing phase objects without halos or directional shadows is proposed. The method is based on transformation of the surface profile of phase objects into a light intensity pattern. The key optical element is an annular aperture at the front focal plane of a condenser. The light flux passing through the annular aperture is changed by the specimen's surface profile and then passes through an objective and contributes to image formation. Theory and experimental results are presented. Phase images of induced pluripotent stem (iPS) cells with clear outlines were obtained with this method.