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22 February 2013 Hyperspectral and gated ICCD imagery for laser irradiated carbon materials
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New optical diagnostics for studying laser ablation and induced combustion for carbon materials are key to monitoring the evolving, spatial distribution of the gas plume. We are developing high speed imaging FTIR and gated ICCD imagery for materials processing, manufacture process control, and high energy laser applications. The results from two projects will be discussed. First, an imaging Fourier Transform Spectrometer with a 320 x 256 InSb focal plane array frames at 1.9 kHz with a spatial resolution of 1 mm and spectral resolution of up to 0.25 cm-1. Gas phase plumes above the surface of laser-irradiated black plexiglass, fiberglass and painted thin metals have been spectrally resolved. Molecular emission from CO, CO2, H2O, and hydrocarbons is readily identified. A line-by-line radiative transfer model is used to derive movies for specie concentrations and temperatures. Second, excimer laser pulsed ablation of bulk graphite into low-pressure (0.05 - 1 Torr) argon generates highly ionized, high speed (M>40) plumes. A gated, intensified CCD camera with band pass filtering has been used to generate plume imagery with temporal resolution of 10ns. The Sedov-Taylor shock model characterizes the propagation of the shock front if the dimensionality of the plume is allowed to deviate from ideal spherical expansion. A drag model is more appropriate when the plume approaches extinction (~10 μs) and extends the characterization into the far field. Conversion of laser pulse energy to the shock is efficient.
© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Charles D. Roberts, Roberto A. Acosta, Michael A. Marciniak, and Glen P. Perram "Hyperspectral and gated ICCD imagery for laser irradiated carbon materials", Proc. SPIE 8603, High-Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications II, 86030Q (22 February 2013);

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