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Proceedings Paper

Mid-infrared microspectroscopic imaging with a quantum cascade laser
Author(s): Kevin Yeh; Matthew Schulmerich; Rohit Bhargava
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Paper Abstract

Conventional mid-infrared (mid-IR) Fourier transform infrared (FT-IR) spectroscopic imaging systems employ an incoherent globar source and achieve spectral contrast through interferometry. While this approach is suitable for many general applications, recent advancements in broadly tunable external cavity Quantum Cascade Lasers (QCL) offer new approaches to and new possibilities for mid-IR micro-spectroscopic imaging. While QCL-based devices have yet to achieve the wide spectral range generally employed by spectroscopists for molecular analyses, they are starting to be used for microscopy at discrete frequencies. Here, we present a discrete frequency IR (DFIR) microscope based on a QCL source and explore its utility for mid-IR imaging. In our prototype instrument, spectral contrast is achieved by tuning the QCL to bands in a narrow spectral region of interest. We demonstrate wide-field imaging employing a 128x128 pixel liquid nitrogen cooled mercury cadmium telluride (MCT) focal plane array (FPA) detector. The resulting images demonstrate successful imaging as well as several unique features due to coherence effects from the laser source. Here we discuss the effects of this coherence and compare our instrument to conventional mid-IR imaging instrumentation.

Paper Details

Date Published: 29 May 2013
PDF: 7 pages
Proc. SPIE 8726, Next-Generation Spectroscopic Technologies VI, 87260E (29 May 2013); doi: 10.1117/12.2015984
Show Author Affiliations
Kevin Yeh, Univ. of Illinois at Urbana-Champaign (United States)
Matthew Schulmerich, Univ. of Illinois at Urbana-Champaign (United States)
Rohit Bhargava, Univ. of Illinois at Urbana-Champaign (United States)


Published in SPIE Proceedings Vol. 8726:
Next-Generation Spectroscopic Technologies VI
Mark A. Druy; Richard A. Crocombe, Editor(s)

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