Partial coherence theory of image formation

The concept of degree of coherence is of great utility in the description of illumination conditions. Our starting point for this analysis is Abbe s theory of microscope imaging, which is applicable to optical lithographic imaging with coherent or 

Optics for photolithography, in Microlithography Science and Technology, J.R. Sheats and B.W. Smith, Eds., p. 195, Marcel Dekker, New York (1998). 

By definition, the numerical aperture of a lens is the sine of one-half its acceptance angle (0), so it follows that the minimum resolvable line width (/ipmin = p/2) should be 

It should be pointed out that Abbe used a uniform source (a lamp) and a substage condenser to form the image in the object plane. For nonuniform sources, 

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