Analysis of deviations in wavelength measurements with a diffraction grating monochromator with respect to a certified reference spectral lamp

Abstract

This paper shows the analysis of the deviations in the wavelength measurements made with a DK-480 monochromator of diffraction grating respect to the values reported for a certified calibration spectral lamp. The radiation emitted by the calibration lamp was dispersed using diffraction gratings of 300, 1200 and 2400 grooves/mm provided in the monochromator. The emitted spectrum contains neutral Mercury and neutral Argon lines, which was registered with a photomultiplier tube coupled to an amplifier circuit. In this study it was applied the method of least squares to the results of the spectral measurements, and it was obtained for each diffraction grating, the linear model or linear fitting of the comparison with respect to the values of the wavelengths of the reference lamp. With the general model of the propagation of the uncertainty, the uncertainty function was obtained for each diffraction grating, in order to estimate the uncertainty of wavelengths interpolated in each spectral range, which are useful for measuring wavelengths of any other spectral source.