SPECTROSCOPY OF PARTIALLY COHERENT FIELDS AT GEOMETRICAL-IMAGE PLANE AND FOURIER-TRANSFORM PLANE OF A LENS

An experimental study of the spectra of a partially coherent field, pr opagating beyond an optical system (a lens), reveals that no spectral shift takes place on the geometrical-image plane, while large blue shi ft occurs at the back focal plane of the optical system for on-axis po ints of observation. Different light sources taken for the study are ( i) partially coherent fields produced by a multimode laser and (ii) a quasi-homogeneous source with different degrees of spatial coherence. These results are consistent with the theory and might find applicatio ns in metrology. (C) 1998 Elsevier Science B.V.