A fourier transform spectrometer based on birefringent interferometer

A simple Fourier transform spectrometer design without moving parts is presented. The compact and rugged design utilizes a birefringent prism, a pair of polarizers and a linear CCD array to achieve this spectrometer design. The advantages of this design over existing FTIR systems are: 1) No moving parts. Therefore these designs are not sensitive to vibration. 2) Much more compact and portable. 3) No scanning is invovled. Instead of timely varying the optical path difference, the optical path difference is spread out spatially, which dramatically reduce the measuring time. In this paper, theoretical models and experimental results are presented. The optical performance of the model is tested using several LEDs of known wavelengths. Fringe counting technique is employed in the interferogram acquisition process to ensure accurate sampling of the interferogram at constant optical path difference intervals. The reconstructed spectra yielded detected wavelengths which deviated by less than 1 nm from the actual wavelengths.