Abstract: A highly luminous device for interferential spectrometry, comprises a birefringent beam-splitting interferometer combined with an optical system supplying localized fringes. As the beam-splitter element, it has at least one birefringent prism mounted along the optical axis of the device and producing an angular splitting, such as a Wollaston prism, of materials suitable for the construction of such prisms and selected as a function of birefringence and transparent over a wide range of wave lengths. The beam-splitter is placed between a polarizer and an analyzer of variable orientation to obtain flux modulation.