LARGE FIELD-OF-VIEW INTERFEROMETERS FOR ENVIRONMENTAL SENSING

The interferometer-spectrometer is a powerful instrument for remotely sensing optical emission spectra associated with the environment. However, when a conventional Michelson interferometer is operated at high spectral resolution, a very narrow viewing field results. For the sensing of emissions which have a significant spatial distribution, which is often the case for environmental species, optical compensation can be employed to open up the field of view. The resulting reduction in observation time for the compensated relative to the uncompensated interferometer is R**2 theta **4/4. For a practical instrument using prism-type compensator elements, the viewing field can be extended to more than ten degrees full angle. Consequently, the observation time required to obtain a spectrum is reduced by more than two orders of magnitude.