30° – 60° – 90° Littrow Dispersion Prisms

TECHSPEC® 30° – 60° – 90° Littrow Dispersion Prisms can be used for a variety of applications. Uncoated littrow dipersion prisms are used to disperse light into its component spectrum. Coated littrow dipersion prisms are used to deviate the line of sight by 60°.

Littrow prisms feature 30°, 60°, and 90° angles, and depending on whether the B-C surface is uncoated or coated, are commonly used as dispersion or beam deviation prisms.

Dispersion Prisms (Uncoated)

Collimated white light enters into the A-C surface of the prism, is reflected at the hypotenuse surface, and then dispersed into its component spectrum at the B-C surface. Although Littrow prisms produce narrower dispersion than equilateral prisms, Littrow prisms are typically less expensive.

Beam Deviation Prisms (Coated)

Incident light enters into the aluminum coated B-C surface of the prism at the nominal angle and returns back using the same path. In spectrum dispersion applications utilizing white light, the resolution performance of Littrow prisms is equal to equilateral prisms since the optical path length through the glass substrate is the same distance round-trip. Additionally, light entered into the A-C surface will reflect twice inside the glass substrate before being emitted through the hypotenuse surface at 60°.