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Proceedings Paper

Mid infrared upconversion spectroscopy using diffuse reflectance
Author(s): Nicolai Sanders; Louis Kehlet; Jeppe Seidelin Dam; Peter Tidemand-Lichtenberg; Pablo Beato; Christian Pedersen
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Paper Abstract

We present a novel approach for mid infrared (mid-IR) spectral analysis using upconversion technology applied in a diffuse reflectance setup. We demonstrate experimentally that mid-IR spectral features in the 2.6-4 μm range using different test samples (e.g. zeolites) can be obtained. The results are in good agreement with published data. We believe that the benefit of low noise upconversion methods combined with spectral analysis will provide an alternative approach to e.g. mid-IR Fourier Transform microscopy. We discuss in detail the experimental aspects of the proposed method. The upconversion unit consists of a PP:LN crystal situated as an intracavity component in a Nd:YVO4 laser. Mixing incoming spectrally and spatially incoherent light from the test sample with the high power intracavity beam of the Nd:YVO4 laser results in enhanced conversion efficiency. The upconverted light is spectrally located in the near infrared (NIR) wavelength region easily accessible for low noise Silicon CCD camera technology. Thus the room temperature upconversion unit and the Silicon CCD camera replaces noisy mid infrared detectors used in existing Fourier Transform Infrared Spectroscopy. We demonstrate specifically that upconversion methods can be deployed using a diffuse reflectance setup where the test sample is irradiated by a thermal light source, i.e. a globar. The diffuse reflectance geometry is particularly well suited when a transmission setup cannot be used. This situation may happen for highly scattering or absorbing samples.

Paper Details

Date Published: 20 February 2014
PDF: 7 pages
Proc. SPIE 8964, Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications XIII, 89641K (20 February 2014); doi: 10.1117/12.2039539
Show Author Affiliations
Nicolai Sanders, Technical Univ. of Denmark (Denmark)
Louis Kehlet, Technical Univ. of Denmark (Denmark)
Jeppe Seidelin Dam, Technical Univ. of Denmark (Denmark)
Peter Tidemand-Lichtenberg, Technical Univ. of Denmark (Denmark)
Pablo Beato, Haldor Topsøe A/S (Denmark)
Christian Pedersen, Technical Univ. of Denmark (Denmark)

Published in SPIE Proceedings Vol. 8964:
Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications XIII
Konstantin L. Vodopyanov, Editor(s)

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