Near-field phase measurement by Fourier analysis of the fringe pattern

Abstract
As for any electromagnetic field the optical near field in the vicinity of an object is fully described by its amplitude and its phase. However, despite the interest in extracting the information contained in the phase variations, until now mainly the intensity has been investigated. In this paper it will be shown that the phase information can be extracted and measured from the detected intensity, by using in the near-field regime techniques developed in conventional far-field interferometry. It will be shown from experimental and theoretical data that the near-field phase can carry information different from the amplitude.