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

Multimode silica step-index optical fibers are examined for use in planar laser-induced fluorescence (PLIF) for combustion diagnostics using ultraviolet (UV) laser sources. The multimode step-index fibers are characterized at UV wavelengths by examining their energy damage thresholds and solarization performance. The beam quality achievable with large clad step-index multimode fibers is also studied. Emphasis is placed on simultaneously achieving high output energy and beam quality (low output M(2)). The use of multimode fibers to deliver UV pulses at 283 nm for PLIF measurements of OH radicals in a Hencken burner is demonstrated. The fiber delivery capability of UV light will benefit combustion diagnostics in hostile environments, such as augmentor and combustor rigs.