Interferometric spectral imaging for three-dimensional objects illuminated by a natural light source

A phase-space analysis of a rotational-shear volume interferometer is presented. It is shown that, in a fairly general condition of this interferometer and by using a Fourier transform method to retrieve spectrodirectional images, a defocus region of the source location exists near the interferometer. This indicates that the usual Fourier transform method has its focal point at an infinite distance. By focusing on finite-depth sources located in the defocus region, a new interferometric method to obtain both three-dimensional spatial information and spectral information of a stationary, quasi-homogeneous, polychromatic source distribution is developed. A key element of this method is the use of a filter function that acts on the volume interferogram of the rotational-shear volume interferometer. This filter function realizes, for a particular position of a monochromatic point source located within the defocus region, a diffraction-limited resolution of the interferometer for the spectrodirectional image.