Wide-field optical imaging of surface nanostructures.

We present a new technique that increases the sensitivity of incoherent light optical microscopy to a point where it becomes possible to directly visualize ultrathin films (approximately nanometers) and isolated nano-objects. The technique is based on the use of nonreflecting substrate surfaces for cross-polarized reflected light microscopy. These surfaces generate a contrast enhancement of about 2 orders of magnitude, extending the application field of wide-field optical microscopy toward the nanoworld. The efficiency of the method is proven experimentally on well-characterized samples. Wide-field imaging of a nonlabeled lambda-DNA molecule is also presented.