A new Fourier transform spectrometer is presented. The novelty of this work comes from the interferometer designed with two identical Wollaston prisms. Thus, the interferogram, formed at infinity in the spatial domain, is independent of the size of the source and of its position. In order to know the characteristics of the apparatus and especially its resolution, we propose the complete calculation of the optical path difference introduced by such an interferometer. Then, by associating the birefringent interferometer with a lens and a linear CCD sensor, we realize a spectrometer with a theoretical resolution about 230 cm−1. Finally, an experimental result is presented, proving the feasibility of the system. © 1999 Society of Photo-Optical Instrumentation Engineers.