Holographic grating spectrometers: Wood's anomalies, spectral response functions, and their dependence on groove density.

Presented is a study of plane holographic gratings with sinusoidal groove profiles, focusing attention on the dependence of grating efficiency on groove density. Experimental spectral response curves are given for a number of gratings with different groove densities in an additive dispersion double monochromator designed for work at visible wavelengths. The Wood's anomalies, both order passing and resonance type, are characterized in each case. Simple equations shall be derived for predicting order passing wavelengths given a fixed angle of deviation between the incident beam and the observed diffraction order. The trend in the strength of the anomalies is compared with theoretical calculations.