Evaluation of adaptive algorithms for detection and classification of fluorescent aerosols in the atmosphere (original) (raw)
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Optics Express, 2010
An improved Dual-wavelength-excitation Particle Fluorescence Spectrometer (DPFS) has been reported. It measures two fluorescence spectra excited sequentially by lasers at 263 nm and 351 nm, from single atmospheric aerosol particles in the 1-10 mum diameter size range. Here we investigate the different levels of discrimination capability obtained when different numbers of excitation and fluorescence-emission wavelengths are used for analysis. We a) use the DPFS to measure fluorescence spectra of Bacillus subtilis and other aerosol particles, and a 25-hour sample of atmospheric aerosol at an urban site in Maryland, USA; b) analyze the data using six different algorithms that employ different levels of detail of the measured data; and c) show that when more of the data measured by the DPFS is used, the ability to discriminate among particle types is significantly increased.
Spectral detection of ultraviolet laser induced fluorescence from individual bio-aerosol particles
2006
We present results of a measurement system designed for detecting the fluorescence spectrum of individual aerosol particles of biological warfare agents excited with laser pulses at wavelengths around 290 or 340 nm. The biological aerosol is prepared and directed into a narrow air beam. A red laser is focused on the aerosol beam and a trigger photomultiplier tube monitor the presence of individual particles by measuring the scattered light. When a particle is present in the detection volume, a laser pulse is triggered from an ultraviolet laser and the fluorescence spectrum is acquired with a spectrometer based on a diffraction grating and a 32 channels photomultiplier tube array with single-photon sensitivity. The spectrometer measures the fluorescence spectra in the wavelength region from 300 to 800 nm. In the experiment we used different simulants of biological warfare agents. These bioaerosol particles were excited by a commercial available gas laser (337 nm), or a laser (290 nm) that we have developed based on an optical parametric oscillator with intracavity sum-frequency mixing. In the analysis of the experiments we compare the measured signals (fluorescence spectra, total fluorescence energy and the scattered energy) from the individual bioaerosol particles excited with the two different ultraviolet wavelengths.
Towards individual aerosol Particle identification using advanced laser spectroscopic techniques
2017
This thesis presents the development and use of an optical device designed for aerosol analysis in different environments. We expose and analyze the results of an organized expedition to better understand the role of marine aerosols on the global climate. This device also enabled us to carry out a campaign of real-time measurements of individual particles from urban aerosols. By integrating advanced techniques of fluorescence depletion spectroscopy (pump-probe) into a portable device, we were able to distinguish, with high selectivity, the aerosols containing amino acids compared to those containing polycyclic hydrocarbons. Finally, we tested this device under real conditions of use. In addition, a comparative test using particle impaction on a filter was performed to confirm the existence of biological material by traditional biochemical analysis. This first test in real conditions of use has allowed us to demonstrate the benefits and limitations of this type of device and builds a...