Dispersing prisms have three 60° angles therefore they are also referred to as equilateral prisms. It provides advantage over diffraction gratings where higher orders diffraction effect is unwanted. Typical applications is wavelength angular separation, where the prism is placed in a beam path to refract the beam twice. Common scheme is to use the prism in minimal deviation angle, which is achieved by aligning the wavelength of interest to travel in parallel to the prism base. This ensures, that angles of incident and refracted beams are equal in respect to corresponding surfaces. This alignment provides benefit of maximum clear aperture and least overall reflection loss for p-polarization.