Fresnel's bi-prism


Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.

bi-prism, Fresnel's 

Optical device consisting of two prisms of very small refracting power, set base to base and which forms two images of a single source. It is often used to produce interference fringes. It may also be used to measure cyclophoria. Syn. double prism; Fresnel's double prism; Maddox bi-prism; Maddox double prism. See interference fringes; Wollaston prism; double prism test.