Remote sensor to detect alcohol impaired drivers

The paper describes a new device; laser alcohol analyzer (LAA); which eliminates the drawbacks of sobriety checking points and allows screening cars or work place for drivers and workers under the influence. The technique uses type III-V distributed feedback tunable diode laser to observe alcohol absorption in the 1.392 pm range. Ethyl alcohol or ethanol (CH₃CH₂OH) has strong absorption bands in the 2.74 μm, 3.39 μm, 7.2 μm, 8.05 μm, and 9.5 μm regions. Strong interference from other gases such as hydrocarbons, H₂O, CO, and CO₂ limit the use of these bands. Moreover, these bands are in the mid-infrared region of the spectrum which requires cooling the laser and the detector to cryogenic temperatures that hinders their applications to sobriety checking points. The LAA sensor uses wavelength modulation absorption spectroscopy to monitor alcohol concentration in moving cars at sobriety check point without slowing the traffic (screening mode), or to determine alcohol concentration from a sample of breath extracted from the driver (testing mode)