Fourier Transformation in Partially Coherent Light

Fourier transformation in partially coherent light has been theoretically studied. It is shown that the intensity distribution at the back focal plane of a lens when a transparency located at the front focal plane and illuminated by a partially space coherent light is given by the convolution of the Fourier transform of mutual intensity function and the autocorrelation function of the object. A similarity between this result and Schell's theorem has been identified.