Abstract
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- μ m wavelengths, the alcohol vapors inside a car can be successfully detected, even in cars with different windowpanes.
Highlights
Stand-off detection of alcohol in moving cars is a particular case of stand-off detection of vapors and gases described in papers.[1,2,3]
We present the idea of using cascade lasers for stand-off detection of alcohol vapors in moving cars as well as the results of the investigations of the experimental setup built to verify the idea
Very important issue is the detection of alcohol in the exhaled air when the concentration is 0.1 mg in 1 dm[3], which is the legal limit of alcohol vapor concentration in many countries.[14,15]
Summary
Stand-off detection of alcohol in moving cars is a particular case of stand-off detection of vapors and gases described in papers.[1,2,3] A device based on this technology can be potentially used to monitor the interior of a vehicle and contribute to eradication of the drunken drivers. As a result of such useful application, this technology enjoys popularity with many scientists and scientific institutions, which is shown in many patents.[4,5,6,7] Much of the effort of the investigators were put into the measurement of the precise value of the alcohol concentration.[6,7] Such approach does not seem to be appropriate for the reason that there are many phenomena disturbing precise measurement that cannot be foreseen and eliminated These are, among others, car cooling system, open windows, window washing liquid (antifreeze), perfumes, or drunken passengers. The ideal situation would be if the absorption coefficients were the same and the ratio of the transmissions was equal to 1 To overcome this obstacle, the solution based on two 1.3- and 1.5-μm laser beams was proposed.[8,10] This approach enabled the measuring of the thickness and inclination of the car windowpanes, which eliminated their impact on the results of the measurements. We present the idea of using cascade lasers for stand-off detection of alcohol vapors in moving cars as well as the results of the investigations of the experimental setup built to verify the idea
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