We discuss a ray and a van Cittert–Zernike characterization of spatial coherence in condensers for projection systems. We present a rule of thumb with which to estimate the modulus of the coherence function at a given point of the illuminated object and a ray-tracing methodology with which to determine this modulus. For uniform illumination of the pupil we relate the modulus of the coherence function and the pupil-filling factor. We suggest that the rms of the angular ray spread at a given object point is an appropriate metric with which to characterize local coherence properties.
© 2001 Optical Society of America
José M. Sasián, Scott A. Lerner, Tony Y. Lin, and Lenny Laughlin, "Ray and van Cittert-Zernike Characterization of Spatial Coherence," Appl. Opt. 40, 1037-1043 (2001)