Fiber-coupled ultraviolet planar laser-induced fluorescence for combustion diagnostics

Loccisano, Frank; Joshi, Sachin; Franka, Isaiah; Yin, Zhiyao; Lempert, Walter R.; Yalin, Azer P.

doi:10.1364/ao.51.006691

Cited by 13 publications

(4 citation statements)

References 29 publications

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“…The overall transmission efficiency is ~70%. The input NA is much less than the NA of the fiber (0.22); therefore, fewer modes are excited, providing a better output beam quality (M 2 ) . The fiber was placed in a six‐axis kinematic mount, which was attached to a linear translational stage that moved along the direction of the laser‐beam propagation.…”

Section: Methodsmentioning

confidence: 99%

“…The input NA is much less than the NA of the fiber (0.22); therefore, fewer modes are excited, providing a better output beam quality (M 2 ). [18] The fiber was placed in a six-axis kinematic mount, which was attached to a linear translational stage that moved along the direction of the laser-beam propagation. The input end of the fiber was positioned behind the focal point of the lens at a location where the beam had expanded to fill~65% of the core area; this positioning reduced the laser intensity at the input surface of the fiber, avoiding damage to the fiber surface.…”

Section: Methodsmentioning

confidence: 99%

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Single‐shot thermometry using fiber‐based picosecond coherent anti‐stokes Raman scattering (CARS) spectroscopy

Hsu

Kulatilaka

Gord

et al. 2013

J Raman Spectroscopy

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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.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Single‐shot thermometry using fiber‐based picosecond coherent anti‐stokes Raman scattering (CARS) spectroscopy

Hsu

Kulatilaka

Gord

et al. 2013

J Raman Spectroscopy

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show abstract

“…Previous studies have shown that silica-based multimode fibers are best suited for long-length delivery of high-power laser pulses because of the minimization of bending and transmission losses. 14–17 Recently, several 10 Hz and 10 kHz PLIF applications that utilize these fibers for ultraviolet (UV) laser-beam delivery have been reported for measurement of concentrations of combustion species such as OH 14–18 and NO 15 in reacting flows. For detection of such minor species with UV-PLIF, high-energy laser beams are required to generate the desirable signal-to-noise (S/N) ratio.…”

Section: Introductionmentioning

confidence: 99%

“…For laser wavelengths below ∼300 nm, solarization effects become prominent causing poor fiber transmission and, hence, introducing additional difficulties in fiber-based measurement. 14–18 Solarization results from UV absorption by fused-silica material, where the transmission loss primarily occurs due to the formation of color defect centers. Furthermore, reduction of the pulse interval between excitation pulses exacerbates the difficulties associated with high-power fiber delivery because the cumulative thermal effects generated by high-repetition-rate lasers can reduce the optical damage threshold of the fiber.…”

Section: Introductionmentioning

confidence: 99%

All Fiber-Coupled OH Planar Laser-Induced-Fluorescence (OH-PLIF)-Based Two-Dimensional Thermometry

et al. 2017

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Two-color, planar laser-induced fluorescence (PLIF)-based two-dimensional (2D) thermometry techniques for reacting flows, which are typically developed in the laboratory conditions, face a stiff challenge in their practical implementation in harsh environments such as combustion rigs. In addition to limited optical access, the critical experimental conditions (i.e., uncontrolled humidity, vibration, and large thermal gradients) often restrict sensitive laser system operation and cause difficulties maintaining beam-overlap. Thus, an all fiber-coupled, two-color OH-PLIF system has been developed, employing two long optical fibers allowing isolation of the laser and signal-collection systems. Two OH-excitation laser beams (∼283 nm and ∼286 nm) are delivered through a common 6 m long, 400 µm core, deep ultraviolet (UV)-enhanced multimode fiber. The fluorescence signal (∼310 nm) is collected by a 3 m long, UV-grade imaging fiber. Proof-of-principle temperature measurements are demonstrated in atmospheric pressure, near adiabatic, CH/O/N jet flames. The effects of the excitation pulse interval on fiber transmission are investigated. The proof-of-principle measurements show significant promise for thermometry in harsh environments such as gas turbine engine tests.

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Voxel-free neural volume reconstruction technique for volumetric flame reconstructions

Zhang

Lei

et al. 2023

Aerospace Science and Technology

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Fiber-coupled ultraviolet planar laser-induced fluorescence for combustion diagnostics

Cited by 13 publications

References 29 publications

Single‐shot thermometry using fiber‐based picosecond coherent anti‐stokes Raman scattering (CARS) spectroscopy

Single‐shot thermometry using fiber‐based picosecond coherent anti‐stokes Raman scattering (CARS) spectroscopy

All Fiber-Coupled OH Planar Laser-Induced-Fluorescence (OH-PLIF)-Based Two-Dimensional Thermometry

Voxel-free neural volume reconstruction technique for volumetric flame reconstructions

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