Sensors 2011, 11(11), 10981-10999; doi:10.3390/s111110981
Article

Thermal Infrared Spectrometer for Earth Science Remote Sensing Applications—Instrument Modifications and Measurement Procedures

1 Department of Earth Systems Analysis, Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, Hengelosestraat 99, P.O. Box 37, Enschede 7500AA, The Netherlands 2 Earth Surface Science, Science Division, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, USA 3 GeoScience Laboratory, Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, Hengelosestraat 99, P.O. Box 37, Enschede 7500AA, The Netherlands
* Author to whom correspondence should be addressed.
Received: 18 October 2011; in revised form: 16 November 2011 / Accepted: 16 November 2011 / Published: 23 November 2011
(This article belongs to the Section Remote Sensors)
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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.
Keywords: vibrational spectroscopy; thermal infrared; Fourier transform infrared spectroscopy; directional hemispherical reflectance; earth science; remote sensing

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MDPI and ACS Style

Hecker, C.; Hook, S.; Meijde, M.; Bakker, W.; Werff, H.; Wilbrink, H.; Ruitenbeek, F.; Smeth, B.; Meer, F. Thermal Infrared Spectrometer for Earth Science Remote Sensing Applications—Instrument Modifications and Measurement Procedures. Sensors 2011, 11, 10981-10999.

AMA Style

Hecker C, Hook S, Meijde M, Bakker W, Werff H, Wilbrink H, Ruitenbeek F, Smeth B, Meer F. Thermal Infrared Spectrometer for Earth Science Remote Sensing Applications—Instrument Modifications and Measurement Procedures. Sensors. 2011; 11(11):10981-10999.

Chicago/Turabian Style

Hecker, Christoph; Hook, Simon; Meijde, Mark van der; Bakker, Wim; Werff, Harald van der; Wilbrink, Henk; Ruitenbeek, Frank van; Smeth, Boudewijn de; Meer, Freek van der. 2011. "Thermal Infrared Spectrometer for Earth Science Remote Sensing Applications—Instrument Modifications and Measurement Procedures." Sensors 11, no. 11: 10981-10999.

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