Spectral changes produced in Young’s interference experiment

Abstract

As was first predicted theoretically by Zernike in a classic paper1 and later verified experimentally by Thompson and Wolf,2 the fringes formed in Young's interference experiment reveal some of the spatial coherence properties of the light incident on the two pinholes. More recently, it was found that Young's interference experiment also provides information about its spectral-coherence properties.3-5 Conversely, the degree of spectral coherence of the incident light affects the spectrum of the light in the fringe pattern. However, a detailed study of the changes in the spectrum produced on super-posing two partially coherent beams does not appear to have been carried out. Our paper is concerned with this problem. We find that although only small changes take place with narrow-band light, drastic modifications in the spectrum can take place when the bandwidth of the incident light is sufficiently broad. Our analysis clearly distinguishes between the contribution due to diffraction and the contribution due to the state of coherence of the light incident on the pinholes.