Reflection interference contrast microscopy of arbitrary convex surfaces.

Current accurate applications of reflection interference contrast microscopy (RICM) are limited to known geometries; when the geometry of the object is unknown, an approximated fringe spacing analysis is usually performed. To complete an accurate RICM analysis in more general situations, we review and improve the formulation for intensity calculation based on nonplanar interface image formation theory and develop a method for its practical implementation in wedges and convex surfaces. In addition, a suitable RICM model for an arbitrary convex surface, with or without a uniform layer such as a membrane or ultrathin coating, is presented. Experimental work with polymer vesicles shows that the coupling of the improved RICM image formation theory, the calculation method, and the surface model allow an accurate reconstruction of the convex bottom shape of an object close to the substrate by fitting its experimental intensity pattern.