Abstract
Optical transfer functions (O.T.F.'s) of a simple plane-grating monochromator were determined by both of experimental and theoretical methods in case of partially coherent image formation. Because of low degree of coherence, the light intensity was regarded to be additive as in the case of incoherent image formation. In an observed spectrogram of Hg 6P–6D lines, the faint shoulder corresponding to the weak 578.97 nm line appeared clearly when it was corrected by means of the O.T.F.'s.