Abstract
The measurement of relative spectral sensitivity of detectors by two-tandem-monochromator method consists of two measuring steps; The measurement of spectral transmittance of a monochromator, and the determination of spectral sensitivity by the combination of the monochromator with the known spectral transmittance and the calibrated standard radiance lamp. This report discusses the two main factors which cause systematic errors in the second step. The one is the effective pass band which is an important quantity in order to estimate the flux which passes through the monochromator. An improved method to give the accurate dispersion curve and the effective pass band is described in detail. This method can exclude the errors which may be the amount of about ±5% in measuring the relative spectral sensitivity. The second one is the corrections to the errors caused by the finite slit width. An equation for the correction and the calculated results based on the measurement of the spectral sensitivity of some detectors are given. The errors are estimated more than 1% in the wavelength region longer than 600nm in case of S-11 type and less than 0.3% in almost whole wavelength region involved in case of S-20 type.
