Etude de l'influence d'un monochromateur sur la cohérence de la lumière

Abstract

The effect of a single- and a double-grating monochromator on the coherence properties of light fields is studied in detail experimentally by measuring the degree of coherence of the field at the entrance and exit slits of a monochromator. It is found that the state of spatial (spectral) coherence of the light field incident at the entrance slit of a monochromator is modified considerably at the exit slits of a single and a double monochromator. The spectral degree of coherence (SDC) at the exit slit of a double monochromator is found to be more than the SDC at the exit slit of a single monochromator. It is therefore necessary that, while synthesizing a secondary source at the exit slit of a monochromator, the coherence properties of the secondary source must be carefully studied to analyse the far-field spectrum of such a source.