Optical surface diffraction and improved lateral resolution

Optical lateral and longitudinal standing waves can be recorded using an optical scanning probe in collection mode. We describe both analytical and numerical methods to determine the image height and the location of a single point scatterer from the recorded surface diffraction image. We find that the phase of the lateral optical standing wave is minimal along the direction of the reflected beam and that the lateral standing waves are centered around the reflected beam direction. We find that the second derivative of the extracted phase peaks at the position of the point scatterer. We have estimated the image height by fitting the envelop function to the recorded intensity profile along the symmetry axis. In the intermediate distance range (several wavelengths off the surface) we can record objects of sizes smaller than the distance between the object and the image plane.