monochromator

[ mon-uh-kroh-mey-ter ]
/ ˌmɒn əˈkroʊ meɪ tər /

noun Optics.

a spectroscope with a slit that can be moved across the spectrum for viewing individual spectral bands.
Also called monochromatic illuminator.

Origin of monochromator

First recorded in 1905–10; monochromat(ic) + (illuminat)or

British Dictionary definitions for monochromator

monochromator
/ (ˌmɒnəʊˈkrəʊmeɪtə) /

noun

physics a device that isolates a single wavelength of radiation