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- Title
Thermal Infrared Spectrometer for Earth Science Remote Sensing Applications--Instrument Modifications and Measurement Procedures.
- Authors
Hecker, Christoph; Hook, Simon; van der Meijde, Mark; Bakker, Wim; van der Werff, Harald; Wilbrink, Henk; van Ruitenbeek, Frank; De Smeth, Boudewijn; van der Meer, Freek
- Abstract
In this article we describe a new instrumental setup at the University of Twente Faculty ITC with an optimized processing chain to measure absolute directional-hemispherical reflectance values of typical earth science samples in the 2.5 to 16 µm range. A Bruker Vertex 70 FTIR spectrometer was chosen as the base instrument. It was modified with an external integrating sphere with a 30 mm sampling port to allow measuring large, inhomogeneous samples and quantitatively compare the laboratory results to airborne and spaceborne remote sensing data. During the processing to directional-hemispherical reflectance values, a background radiation subtraction is performed, removing the effect of radiance not reflected from the sample itself on the detector. This provides more accurate reflectance values for low-reflecting samples. Repeat measurements taken over a 20 month period on a quartz sand standard show that the repeatability of the system is very high, with a standard deviation ranging between 0.001 and 0.006 reflectance units depending on wavelength. This high level of repeatability is achieved even after replacing optical components, re-aligning mirrors and placement of sample port reducers. Absolute reflectance values of measurements taken by the instrument here presented compare very favorably to measurements of other leading laboratories taken on identical sample standards.
- Subjects
REMOTE sensing in earth sciences; FOURIER transform infrared spectroscopy; REFLECTANCE; DATA analysis; ANALYSIS of variance
- Publication
Sensors (14248220), 2011, Vol 11, Issue 11, p10981
- ISSN
1424-8220
- Publication type
Article
- DOI
10.3390/s111110981