This study concerns remote detection of alcohol vapors in cabins of moving vehicles. By means of a simplified description of propagation of two combined laser beams differently absorbed in alcohol vapors and in vehicle windowpanes, difficulties in detecting alcohol vapors in vehicle cabins using classical differential absorption method are demonstrated. Unreported in the literature, this method of remote detection of alcohol vapors in the air exhaled by a driver or a passenger in moving vehicles is proposed. The method uses two combined laser beams that illuminate different zones in the car cabin through the same windowpane. Based on the correlation between the spread of the transmission of these zones and the alcohol concentration in the air exhaled by a drunken person, it is possible to determine if the alcohol exists in the exhaled air. The effectiveness of the presented method is confirmed experimentally.
The paper describes the results of experimental research on the mobile verification of travellers based on fingerprints. Three-day tests were carried out at the border crossing in Terespol, Poland. The developed system automatically acquires personal and biometric data (fingerprints) from the Polish biometric passport, determines their quality and compares with the live data collected from the traveller. In addition, the system measures the time of individual stages of the process and determines total transaction time. For total number of correctly scanned travellers equal to 128, false acceptance rate equals to 0, while rejection rate is less than 1%. The average transition time of border check was 37 seconds.
The phenomenon of laser light scattering provides the technology for visualization and testing the inner structure and homogeneity of materials. Some of them excited by the laser light in the tomographic process can emit light the wavelength of which is different than that of excitation laser. Such photoluminescence can be a source of additional information of the material’s structure. Combining the Laser Scattering Tomography (LST) and Spectrometry techniques has enabled us to develop a new type of an LST technique. The system is useful for investigations of various materials like semiconductors (Si, GaAs) ceramics, crystals for passive absorbers for high power pulse lasers, and laser crystals.
On the basis of thermally bonded Er,Yb:glass/Co:MALO microchip a laser head pumped by fiber coupled laser diode was designed. The performance of the laser head were investigated and the main output parameters were determined. The energy over 40 μJ in 3.8 ns pulse with repetition rate of 0.735 kHz was achieved. The laser head characterized by such parameters can successfully be used in tele-detection applications.
In the paper we describe a new construction and preliminary laboratory tests of airborne particle flow detector. The device is designed for continuous monitoring of biological particles in ambient air. The scattering and fluorescence signals from each particle are detected simultaneously. The device uses 375 nm laser for fluorescence excitation. The luminescence is measured with three broad bands. Principal Component Analysis was applied for data analysis. It has been demonstrated proper classification between various biological aerosols.
In this article we present the research on optoelectronic system for stand-off detection of alcohol vapours in moving cars. The idea of using commercially available cascade lasers was presented. Special attention was paid to the optical characteristics of the car windowpanes. It was shown that using 3.45 μm and 3.59 μm wavelengths the alcohol vapours inside a car can be successfully detected even for cars with different windows
The idea of using commercially available cascade lasers for stand-off detection of alcohol vapors in moving cars is presented. Special attention is paid to the optical characteristics of the car windowpanes for the monitoring as well as for the reference laser beams. A special experimental setup was built to investigate the idea. It is shown that using interband cascade lasers operating at 3.45- and 3.59-μm wavelengths, the alcohol vapors inside a car can be successfully detected, even in cars with different windowpanes.
The results of experiments concerning detection of alcohol vapors in car cabins using a laboratory device, which was developed and built at the Institute of Optoelectronics at the Military University of Technology, are described. The work is a continuation of the investigations presented in an earlier paper. On the basis of those results, the whole device was designed and built. Then it was investigated using a car with special system simulating a driver under the influence of alcohol. To simulate the appropriate concentration of alcohol in human blood, a special method of generation of alcohol vapor was developed.
Some aspects of stand-off detection of alcohol in simulated car cabins are described. The proposed method is the well-known “difference absorption” method applied to the differential absorption lidar system, modified by taking advantage of a third laser beam. The modification was motivated by the familiar physical phenomena such as dispersion and different absorption coefficients in window panes for applied laser wavelengths. The mathematical expressions for the method were derived and confirmed by experiments. The presented investigations indicate that the method can be successfully applied to stand-off detection of ethyl alcohol in moving cars.
Fluorescence analysis of dry samples of biological origin like pollens, fungi, flours and proteins was presented. In the laboratory study presentenced here two fluorescence methods using semiconductor light sources were applied. Firstly, laser induced fluorescence emission (LIF) spectra of the samples were recorded under 266 and 375 nm excitation. The second technique covered fluorescence decay (FD) at 280 and 340 nm excitation. Hierarchical Cluster Analysis (HCA) of acquired spectra and decays was performed. Both LIF and FD showed that single wavelength excitation 266 and 280 nm, respectively allow distinguishing of pollens from other samples. Combining data of both excitation wavelengths, for LIF and FD, respectively, resulted in substantial improvement of data classification for groups according to the samples origin.
LIDAR system for real-time standoff detection of bio-agents is presented and preliminary experimental results are
discussed. The detection approach is based on two independent physical phenomena:
(1) laser induced fluorescence (LIF),
(2) depolarization resulting from elastic scattering on non-spherical particles.
The device includes three laser sources, two receiving telescopes, depolarization component and spectral signature
analyzing spectrograph. It was designed to provide the stand-off detection capability at ranges from 200 m up to several
kilometers. The system as a whole forms a mobile platform for vehicle or building installation. Additionally, it's
combined with a scanning mechanics and advanced software, which enable to conduct the semi-automatic monitoring of
a specified space sector.
For fluorescence excitation, 3-rd (355 nm) and 4-th (266 nm) harmonics of Nd:YAG pulsed lasers are used. They emit
short (~6 ns) pulses with the repetition rate of 20 Hz. Collecting optics for fluorescence echo detection and spectral
content analysis includes 25 mm diameter f/4 Newton telescope, Czerny Turner spectrograph and 32-channel PMT.
Depending on the grating applied, the spectral resolution from 20 nm up to 3 nm per channel can be achieved.
The system is also equipped with an eye-safe (1.5 μm) Nd:YAG OPO laser for elastic backscattering/depolarization
detection. The optical echo signal is collected by Cassegrain telescope with aperture diameter of 12.5 mm.
Depolarization detection component based on polarizing beam-splitter serves as the stand-off particle-shape analyzer,
which is very valuable in case of non-spherical bio-aerosols sensing.
Laser Induced Fluorescence (LIF) could permit fast early warning systems either for point or stand-off detection if a reliable classification of warfare biological agents versus biological or non-biological fluorescing background can be achieved. In order to improve LIF discrimination capability, a new system is described in which the fluorescence pattern is enriched by the use of multiple wavelength delayed excitation while usual spectral fluorescence analysis is extended to time domain to use both aspects as criteria for classification. General considerations and guidelines for the system design are given as well as results showing good discrimination between background and simulants.
The results of spectroscopic and generation investigations of the concentrated Yb-Er laser glasses with different
concentrations of dopants are presented. Absorption coefficient was calculated on the basis of measured transmission
spectra of the laser glasses. Two regimes of the laser generation were investigated: cw and quasi-cw. Up to 180mW of
output power with slop efficiency 18,5% for cw generation and up to 340 mW of peak power with slop efficiency 22 %
for quasi-cw generation and duty-cycle 50% was achieved. The dependence of the output power on the temperature of
the pumping diode and the active media were examined.
The paper describes the results of spectroscopic and generation investigations of SELG glasses with different
concentrations of dopants for high-average power diode-pumped eye-safe microchip lasers. Transmission spectra of the
laser glasses was measured and absorption coefficient calculated. The generation was carried out in two regimes: cw and
quasi-cw. Up to 150mW of output power with slop efficiency 16% was achieved for cw generation and up to 300 mW of
peak power with slop efficiency 19,4% for quasi-cw generation and duty-cycle 50%.
The paper presents investigation results of 1064 nm and 532 nm microchip lasers used for microinterferometer systems.
Due to the developed designs, the output power of 10 mW and 8 mW of CW radiation at 1064 nm and 532 nm was
obtained at the outputs of single-mode fibers, of core diameters of 6 &mgr;m and 3 &mgr;m, respectively. Spectral characteristics
were examined and measurements of transverse distributions of laser beam were carried out. Using Michelson
interferometer, optical beam quality was investigated as well as temporal and spatial coherences were determined. Mode
structure of 1064 nm and 532 nm microchip lasers radiation were examined with Fabry-Perot interferometer. The
obtained results proved wide range of possibilities of application of the designed microchip lasers in optoelectronic
systems of measuring devices.
EX-EM fluorescence matrices from suspensions of 11 vegetative bacteria, 5 spores, and 14 interferents (fungi, pollens)
were measured and cross-sections of the selected bacteria were calculated. The changes of fluorescence characteristics of
vegetative cells during their sporulation and starvation to death as well as spores during germination are shown.
Influence of culture media on emission spectra and rate of spores formation under starving conditions was examined.
Analysis of the measured fluorescence characteristics shows that double- or multi-wavelenghts excitation can make it
possible to distinguish between particular groups of biological material, i.e., spores, vegetative cells, proteins, and
interferents.
Most of the work on passively Q-switched microchip lasers emitting at 1064 nm has been done with neodymium-doped YAG crystals as gain material and Cr4+:YAG as saturable absorber. The bulk Cr4+:GGG Czochralski grown passive Q-switches were also investigated. We have used a technique of liquid phase epitaxy (LPE) to grow Cr4+:YAG, Cr4+:GGG and Co2+:YAG thin films of saturable absorber. X-ray diffraction analysis, optical transmission spectra measurements and passive Q-switching experiments were performed to characterize the obtained layers. Absorption saturation measurements of Cr4+:YAG, Cr4+:GGG and Co2+:YAG layers were carried out at 1.06 μm and 1.54 μm, respectively.
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