Feature

Three Dimensional Reconstruction of Random Radiation Sources

Joseph Rosen

The degree of the spatial coherence of an electromagnetic field is a useful function mainly for two reasons. First it provides information on the spatial coherence of light sources. Second, due to the Van Cittert-Zernike theorem, knowledge of the coherence distribution induced by a source, enables one to compute its shape. Explicitly, it is manifested in this theorem that the two-point degree of coherence in the far field of a quasi-monochromatic, spatially incoherent light source is proportional to the Fourier transform of the source's planar intensity distribution. Therefore, by measuring the two-point degree of coherence in the far field, one can image the source distribution. This imaging technique is, among others, the theoretical basis of the very long base-line interferometers used in astronomy. However, this technique has been limited to imaging of planar two-dimensional objects.