The present invention is directed to a monochromator device which uses single grating volume holograms. The holograms collect light of varying wavelengths such as polychromatic light, and separate one particular wavelength of interest. A wide wavelength spectrum can be targeted, either by angularly tuning the holograms, or by using an array of holograms each of which is tuned to a different center wavelength. The large aperture and high angular dispersion of the volume holograms provides a higher light throughput than that of prior art monochromators. The present invention can be used anywhere that efficient separation of polychromatic light into its narrowband components is required. The monochromator may be placed immediately before a light source, or before other optical or signal processing devices to provide the filtered wavelength of light input to such devices.