Newton's rings in near-field optics

We show how Newton's rings manifest themselves in near-field scanning optic al microscopy and discuss how this effect can be used with topographic imag ing to measure correlated roughness of thin films. In conventional optics, transmission through a thin nonabsorbing film depends on film thickness whe n multiple reflections from the film boundaries are coherent. Measurements and modeling of the transmission through thin films illuminated by a near-f ield probe show that these oscillations are present despite the large distr ibution of transverse wave vectors needed to describe light from the probe. (C) 2001 American Institute of Physics.