Littrow prism

glass

Littrow Prisms are of the same design as Brewster prisms but cut in half vertically from the apex to the base. They are normally used in a laser cavity or prism spectrometer to select a particular wavelength. In general, the beam is incident on the hypotenuse and is reflected back from the rear surface. It exits from the hypotenuse dispersed into its constituent wavelength components. Tuning is accomplished by tilting. Ealing Littrow Prisms are supplied uncoated but should be coated with an antireflection coating designed for 45° for optimal performance.