1) Optical device 
A polychromator is an optical device that is used to disperse light into different directions to isolate parts of the spectrum of the light. A prism or diffraction grating can be used to disperse the light. Unlike a monochromator, it outputs multiple beams over a range of wavelengths simultaneously. Monochromators have one exit slit and one wavele...
A device for isolating narrow portions of the spectrum by dispersing light into its component wavelengths.