The SESAME FPI (Satellite Experiments Simultaneous with Antarctic MEasurements Fabry-Perot Interferometer) measured Doppler shifts by imaging the wavelengths of oxygen emissions with high resolution and precision. The instrument comprised of five optical components: a scanning mirror that viewed in the 4 cardinal directions at 30 deg elevation; an etalon that consisted of a pair of quartz plates; a 1-m focal length Cassegrain telescope; a 1-nm filter wheel and an imaging photon detector. The experiment contributed to the understanding of airglow and auroral processes in the thermosphere.