Dr. Jun Kojima of the Ohio Aerospace Institute with Dr. David Fischer and Dr. Quang-Viet Nguyen of the NASA Glenn Research Center recently tested a new architecture for SRS laser spectroscopy to realize time-resolved combustion diagnostics.
The new experimental apparatus features a 200 W second-harmonic Nd:YAG pulse laser to measure Raman scattering. This new technology provides much faster gating than previously reported techniques, a wider dynamic range and higher sensitivity in combustion. The high-speed diagnostics are enabled by the utilization of an emICCD camera and the latest 10-kHz laser (Patara-HP200). This technique allows scientists and engineers to capture molecular signatures in combustion in a shorter period (e.g., 3000 shots can be accumulated in 0.3 s to record signal with higher SNR).
Cutting Edge Optronics manufactured the laser that was used as the excitation source. The laser was operated at a 10-kHz repetition rate to interrogate a flame, and the scattering light was collected by fiber-coupled lens optics and transmitted to a volume-transmissive lens spectrograph equipped with the emICCD camera. This diagnostic system reached the highest signal level ever achieved in the NASA facility.
Dr. Kojima’s assessment of the 10-kHz Laser:
For more details about the time-resolved SRS set up, click here.
Kojima, J and Shah, M. “Time-Resolved SRS Spectroscopy Facilitates Combustion Research.” Photonics Spectra. Dec. 2013. Apr. 2014.
Approved for Public Release 14-0864
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