The influence of nonparaxiality on the spectral behavior in Young's experiment illuminated by partially coherent light

Starting from the Rayleigh--Sommerfeld diffraction integral, thispaper studies the spectral behavior in Young's experimentilluminated by nonparaxial partially coherent light and compareswith the paraxial case, where the influence of nonparaxiality ofpartially coherent light on the spectral shifts and spectralswitches is stressed. It is shown that there is a spectral shift inthe nonparaxial case relative to the paraxial one and the criticalposition changes, at which the spectral switch occurs. The ratio ofthe waist width to the central wavelength $w_{0}/lambda _{0}$ andrelative spatial correlation length $De$ affect the spectraldifference. The smaller $w_{0}$/$lambda _{0}$ is, the larger thedifference between the nonparaxial and paraxial results appears. Theeffect of relative spatial correlation length $De$ is relativelysmall.