The Composite Infrared Spectrometer (CIRS) consists of two spectrometers (Far-Infrared and Mid-Infrared) which share a 50 cm, F/6 Telescope and Mirror Transport Mechanism. The spectral resolution is 0.5 to 20 cm-1 with range of 10 to 1400 cm-1 (1000-7 microns).
The Far-IR Spectrometer is a Polarizing Interferometer with a single focal plane, known as Focal Plane 1 (FP1). This focal plane has a spectral range of 10-600 cm-1 and consists of two thermophile detectors with field-of-view at 4.3 mrad in diameter.
The Mid-IR Spectrometer consists of two 1 x 10 HgCdTe detector arrays. The Focal Plane 3 (FP3) array has a spectral range of 600-1100 cm-1 . The Focal Plane 4 (FP4) array has a spectral range of 1100-1400 cm-1. The field-of-view per pixel for each is 0.273 mrad square.