A study of the spectral shifts of a well-known type of partially coher
ent field, namely, one formed by Gaussian model beams, propagating bey
ond an optical system reveals that there are no shifts in the geometri
c-image plane, whereas the greatest (blue) shift occurs in the back fo
cal plane. These results are relevant for spectroradiometric measureme
nts. (C) 1997 Optical Society of America.