Escaping radiation:

The escaping radiation then undergoes interference along with the transmitted portion of the radiation. The radiation for that the filter spacing is a multiple of a half wavelength (n (λ/2)) undergoes constructive interference while the radiation of other wavelengths undergoes destructive interference. The destructive interference of the radiation is not done in the cases whereas the half wavelengths multiples are close to, but not accurately equal to the spacing among the metal films. These also appear in the transmitted radiation and as a consequence the transmitted radiation is a band of radiant energy and not a single wavelength.

Most modern fluorimeters used in analytical laboratories commonly use diffraction grating monochromators.  Such a fluorescence spectrometer is capable of recording both excitation and emission spectra and thus makes full use of the analytical potential of the methods. While monochromators are employed, it should be possible to modify the slit width of the excitation and emission both monochromators independently.