Hydroxyl radical planar laser-induced fluorescence imaging in flames using frequency-tripled femtosecond laser pulses. | Academic Article individual record
abstract

Ultra-short optical pulses in the ultraviolet (UV) region are of significant interest for combustion and reacting flow diagnostics, as most important chemical species have electronic resonance transitions in the UV region. Optical parametric amplifiers are typically used for frequency conversion of femtosecond (fs) pulses from near-IR to UV; however, their implementation for practical imaging applications is limited because of the low conversion efficiency and extreme sensitivity to ambient conditions. In this work, we report the implementation of direct-frequency-tripled, fs laser pulses from a tunable amplified laser system for high-resolution imaging of hydroxyl (OH) radical in flames. The fundamental laser output near 850 nm is frequency tripled to obtain approximately 283.3-nm UV radiation. OH planar laser-induced fluorescence (PLIF) imaging at 1 kHz is demonstrated in turbulent flames with image sheet heights in excess of 45 mm and a signal-to-noise ratio better than 25. These results represent over 3 increase in the imaging dimensionality compared to traditional OPA-based systems. Additionally, the third-harmonic generation apparatus is compact, robust, and easy to operate while providing near-Gaussian beam profiles. Simple power scaling suggests another factor of 3 or more increase in sheet height can be achieved for kilohertz-rate practical combustion diagnostics applications.

publication outlet

Opt Lett

author list (cited authors)
Jain, A., Parajuli, P., Wang, Y., & Kulatilaka, W. D.
publication date
2020
publisher
keywords
  • 0299 Other Physical Sciences
  • 0205 Optical Physics
citation count

1

PubMed ID
32870833
identifier
485318SE
Digital Object Identifier (DOI)
start page
4690
end page
4693
volume
45
issue
17