Scanning differential phase contrast optical microscope: application to surface studies

The characteristics and theory of operation of a new scanning differential phase contrast optical microscope are described, and a number of results are presented. High-contrast micrographs of a polished stainless steel sample are included, showing clearly the grain boundaries as well as some fine structure within the grains. Micrographs are also presented of natural diamonds both in polished and unpolished forms. In the former many polishing lines are visible, and in the latter one can clearly see a large number of stacking faults. Results on the study of monolayers of Langmuir-Blodgett films are also presented. The micrographs clearly show the boundaries as well as nonuniformities within the films. The ability of our system to image objects showing refractive-index variation is demonstrated by producing micrographs of an exposed but undeveloped photoresist film and a partially doped Si sample. In each case a qualitative comparison is made with the differential interference (Nomarski) micrograph of the same field of view.