This paper deals with the influences of diffrac tdegrees of coherence on the image field distribution of standard objects.Indicating the very close connections between the illuminating condition and image formation in partially coherent illumination optical systems.Based on and simplified the imagery theory of H.H.Hopkins

a FORTRAN program to simulate image of one dimensional standard objects under partially coherent illumination has been developed

thus obtaining a reliable method for selecting the optimal illuminating condition and for evaluating the optical system with partially coherent illumination.Our calculation on optical system with aberration shows that the image intensity distribution of a standard object can reflect sensitively the image qualily of the optical systems which therefore can be adopted as a quality criterion for practical optical systems with partially coherent illumination