Peter A. DeBarber

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An imaging technique based on Raman scattering induced by a KrF excimer laser has been developed for quantitative simultaneous multiple-point measurements of absolute multispecies concentrations (O(2), N(2), H(2), and H(2)O) and temperature in turbulent flames. These multiparameter measurements along the laser line have a temporal resolution of 17 ns, a(More)
We report on the detection and analysis of signals generated from gas-phase laser-induced gratings over a large range of static pressure (0.04-100 atm). We employed the experimental technique of laser-induced thermal acoustics and performed measurements on mixtures of NO(2) in air and CO(2) as a function of pressure. Accurate analysis of the acquired data(More)
A temporally resolved approach for measurement of two-dimensional temperature fields in reacting flows is experimentally investigated. The method, based on planar laser-induced fluorescence of the hydroxyl (OH) radical, is applicable in many combustion environments, including variable density flow fields. As a means of examining the accuracy of the(More)
Ozone tagging velocimetry is developed for unseeded velocity measurement of air flows. An ozone line is photochemically created by an ArF excimer laser. After a fixed time delay the ozone line is imaged with a KrF excimer laser sheet (248 nm) that photodissociates the ozone and produces vibrationally excited O(2). The O(2) is excited by the same 248-nm(More)
We analyze the random process of fluorescence reabsorption and trapping in solid-state optical materials in general and its influence on the efficiency of optical cooling of solids by anti-Stokes fluorescence in particular. Using the absorption and fluorescence spectra of Yb3+:ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) as input data, we employ a random-walk model to(More)
Two complementary unseeded molecular flow tagging techniques for gas-flow velocity field measurement at low and high temperature are demonstrated. Ozone tagging velocimetry (OTV) is applicable to low-temperature air flows whereas hydroxyl tagging velocimetry (HTV) is amenable to use in high-temperature reacting flows containing water vapour. In OTV, a grid(More)
The photorefractive semiconductor ZnTe:V:Mn is investigated for use in real-time resonant holographic interferometry applications. Experimental results of two-wave and four-wave mixing with pulsed dye and cw diode lasers are presented; in addition holographic image transfer, as well as two-wavelength resonant holographic interferometry, are demonstrated.(More)
We demonstrate real-time, two-dimensional measurement of species concentration in a turbulent flow field. The dynamics of pulsed holographic recording and decay are characterized for a 46-microm polymer film containing bacteriorhodopsin. We produced species-specific holographic interferograms of sodium vapor by simultaneously recording two holograms at(More)
Foodborne illness presents a public health challenge in USA. There is an urgent need for the federal government and food industries to expand efforts to prevent any food contamination that potentially could be harmful to human health. The Food Safety Laboratory (FSL), ARS, USDA, is one of the leading laboratories for the development of optoelec-tronic(More)
We have made simultaneous temperature measurements by degenerate four-wave mixing (DFWM) and absorption spectroscopy of OH in a CH(4)-air, lifted-diffusion flame. After we corrected the DFWM data for laser beam absorption of as much as 60%, the DFWM-based temperatures were in good agreement with temperatures derived strictly from the absorption data, as(More)