Abstract: Assuming paraxial approximation and quasi-monochromacy,the diffraction of Partially Coherent Light is investigated.It has been verified that the intensity distribution in the diffraction pattern is proportional to the convolution of the intensity distribution,due to a monochromatic point light source and a Fourier transformation of Mutual Coherence Function in the test plane.This result is valid in both diffraction cases:i,e,in the near field, as well as in the far field.Especially,the effect of the Mutual Coherence Function on the spectrum of intensity distribution of ideal diffraction is also discussed after the contrast function is introduced.

Key words: diffraetion, contrast, partial coherence