Spectrometers
type: Concept

FIRSC
type: Concept
definition: A Far Infrared Sensor for Cirrus (FIRSC) is a a Fourier transform spectrometer (FTS) configured as a Martin-Puplett polarizing interferometer. In a Martin-Puplett configuration, dihedral (roof-top) mirrors replace the usual flat mirrors of a Michelson interferometer and a linear polarizing grid is the beamsplitter. The instrument can operate in intensity or polarization measuring mode. The Martin-Puplett configuration provides two separate input and output ports defined by reflection/transmission from input and output polarizer elements. The measured spectrum is the difference of two input ports consisting of the nadir scene and a controlled temperature blackbody source. The two output ports provide the two spectral channels. Additional information available at "http://nit.colorado.edu/~evans/mwcirrus/FIRSC/" [Summary provided by the University of Colorado]
in scheme: instruments