The spectral slit width of a monochromator is defined as the half-intensity band width of frequencies passed by the exit slit. This paper discusses its measurement using methods similar to those used to measure the frequency transmission of electrical networks. A Fabry-Pérot interferometer, used as a sinusoidal signal generator, produces interference fringes constantly spaced in wave numbers at a known amplitude input to the monochromator. It can be shown that the attenuation of the fringe pattern as the spacing is changed is a function of the exit-slit output-intensity distribution function. From this information the spectral slit width in any spectral region can be measured and the exit-slit function indicated.
The sensitivity of measurement is limited by the fringe amplitude obtainable from the interferometer, which is a function of the reflectivity of the interferometer plates and their adjustment. Rays passing through the interferometer at other than normal incidence tend also to damp the fringe pattern.
© 1955 Optical Society of AmericaFull Article | PDF Article
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