This article is from the ECONOS part of the joint special issue on the European Conference on Nonlinear Optical Spectroscopy (ECONOS 2012) with Guest Editors Johannes Kiefer and Peter Radi and the II Italian Conference of the National Group of Raman Spectroscopy and Non-Linear Effects (GISR 2012) with Guest Editor Maria Grazia Giorgini.
Single-shot thermometry using fiber-based picosecond coherent anti-stokes Raman scattering (CARS) spectroscopy†
Article first published online: 1 MAR 2013
Copyright © 2013 John Wiley & Sons, Ltd.
Journal of Raman Spectroscopy
Special Issue: Joint special issue on the European Conference on Nonlinear Optical Spectroscopy (ECONOS 2012) and the II Italian Conference of the National Group of Raman Spectroscopy and Non-Linear Effects (GISR 2012)
Volume 44, Issue 10, pages 1330–1335, October 2013
How to Cite
Hsu, P. S., Kulatilaka, W. D., Gord, J. R. and Roy, S. (2013), Single-shot thermometry using fiber-based picosecond coherent anti-stokes Raman scattering (CARS) spectroscopy. J. Raman Spectrosc., 44: 1330–1335. doi: 10.1002/jrs.4280
- Issue published online: 22 OCT 2013
- Article first published online: 1 MAR 2013
- Manuscript Accepted: 28 JAN 2013
- Manuscript Revised: 24 JAN 2013
- Manuscript Received: 18 OCT 2012
- AFRL. Grant Number: FA9101-09-C-0031
- AFOSR. Grant Number: FA8650-10-C-2008
- picosecond coherent anti-stokes Raman scattering;
- fiber optics;
- combustion diagnostics
Coherent anti-Stokes Raman scattering (CARS)-spectroscopy-based thermometry techniques developed for laboratory flames face a stiff challenge when implemented in practical combustion environments such as engine test facilities. In addition to limited optical access, the harsh environments associated with these test facilities (i.e. uncontrolled humidity, vibration, and large thermal gradients) often restrict the operation of sensitive laser systems. To circumvent this problem, we have developed a fiber-based, picosecond (ps) CARS system employing long-length (up to 6 m), multimode silica fibers that permits the laser system to be isolated from the high heat and vibration of the test hardware. Proof-of-principle, single-laser-shot temperature measurements using a 3-m-long fiber system are demonstrated in atmospheric pressure, near-adiabatic, laboratory H2–air flames. Limitations that are imposed by long-length multimode-fiber beam delivery for CARS thermometry are identified as nonlinear effects during beam propagation along the fiber, depolarization of the laser beam, and degradation of the beam quality at the output of the fiber. These effects are investigated in detail, and potential improvements are suggested. The current study shows promise for implementation of fiber-based ps-CARS spectroscopy in harsh environments such as those encountered in combustors and afterburners in practical gas-turbine-engine test facilities. Copyright © 2013 John Wiley & Sons, Ltd.