The position of wavelength in a grating spectrometer depends mainly on the line frequency and the working angle of the grating, as calculated by Eqs. (2.1), (2.4), and (2.5), and derivations. A prism spectrometer will output a certain wavelength as a function of the prism dispersion, which depends on the RI of the prism at the wavelength of interest, the angle of the prism, and the illumination angle, as calculated by Eq. (3.3). However, there are more parameters that affect the actual wavelength output: the internal angles of the spectrometer, which are part of the above equations, and the actual temperature, which can change the wavelength, as described by Eq. (2.31). Furthermore the output position of a wavelength can change with the illumination of the entrance and after the instrument experiences vibrations or shock. It should be noted that any modification of the beam travel inside the spectrometer can affect the calibration. It follows that the energy axis (wavelength, wavenumber, photon energy) needs to be checked frequently and calibrated sometimes.
Online access to SPIE eBooks is limited to subscribing institutions.