1. A common path, interferometric imaging system for forming a resolution-enhanced image of a sample, comprising: an illumination source that sequentially illuminates the sample from different directions to form for each illumination a plurality of substantially unscattered light components and substantially scattered light components that have a relative phase; an optical imaging system that has a pupil and that, collects and images the substantially scattered light components and the substantially unscattered light components for each illumination, wherein the substantially scattered light components, and the substantially unscattered light components pass through a portion of the pupil; a variable phase shifting system located substantially at the pupil and that varies said relative phase by at least three different amounts for each illumination; a detector having an array of pixels that sense for each illumination an intensity of combined portions of the substantially scattered light component and the substantially unscattered light component after the relative phase is adjusted and after they have interfered with one another, and that generates in response thereto at least three raw images; and processing means operably connected to the detector for receiving and processing the at least three raw images for each illumination and forming therefrom a complex amplitude of an optical field for each detector pixel, and Fourier-processing the complex amplitudes for each illumination to form the resolution-enhanced image of the sample.