Thermal Infrared Profiling Spectrometer (TIPS)

The Thermal Infrared Profiling Spectrometer (TIPS) is an airborne/spaceborne sensor concept developed at DLR-Institute for Optoelectronics for scientific observations in remote sensing of the earth surface. The patented spectrometer design is based on a fast scanning Fourier spectrometer (FSM) using a rotating retroreflector to achieve the appropriate path alteration thus avoiding the usual linear movement of one of the mirrors in an conventional Michelson interferometer. The spectral band covers the 3 - 13 μm band with a spectral resolution of 5 cm-1 (50 nm at 10 μm). The measured signal is an interferogramm, derived quantities are spectral emissivity, spectral radiance and surface temperature. The optical system consists of an aperture filling plane tilting mirror to provide off-nadir observation and calibration mode. The collecting mirror focal length and the detector area yields an instantaneous field of view (ifov) of 1.2 mrad, noise equivalent temperature resolution of 0.04K (300K), and a noise equivalent change in emissivity Δεof 6 x 10-4. Calibration is performed by two aperture filling area blackbodies at two different temperatures. An extensive simulation of signal/noise performance of the TIPS has been evaluated by means of the simulation programm SENSAT9, developed by DI.R. This simulation comprises the sensor performance, typical variations of atmospheric conditions and selected spectra from ground surfaces. Results of this simulation are discussed and a description of the sensor is presented.