During the mid During the mid 1990s, the Geophysical Institute developed an imaging Fabry-Perot spectrometer capable of mapping wind an temperature fields in Earth's thermosphere by means of ground-based optical remote sensing. This instrument, located at Poker Flat, originally used a photon-counting detector that was later replaced with an intensified CCD camera. I have recently returned from working at LaTrobe University in Australia, during which time we developed a "next generation" version of the imaging spectrometer and deployed it at Mawson Station in Antarctica. The Mawson instrument features an electron multiplying CCD camera, better fringe-imaging optics, more self-calibration capabilities and improved operating software that provides more flexible observing modes. We are now in the process of upgrading the Poker instrument to incorporate these same capabilities, as well as starting construction of a whole new one for the US Air Force. In this talk I will present the principle of operation of these instruments, the salient features of the new design and some initial results from Mawson.