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Abstract

On-board ILS ethyl alcohol sensors based on intracavity laser spectroscopy (ILS) are provided for detecting the presence of ethyl alcohol vapors in a vehicle. The sensor comprises: (a) a laser comprising a gain medium having two opposed facets within a laser resonator and functioning as an intracavity spectroscopic device having a first end and a second end, the first end operatively associated with a partially reflecting (i.e., partially transmitting) surface; (b) a reflective or dispersive optical element (e.g., a mirror or a diffraction grating) operatively associated with the second end to define a broadband wavelength laser resonator between the optical element and the first end and to thereby define an external cavity region between at least one facet of the gain medium and either the first end or the second end or both ends; (c) the external cavity region being exposed to air in the cabin of the vehicle to enable any ethyl alcohol molecules to enter thereinto; (d) a detector spaced from the first end; (e) appropriate electronics for measuring and analyzing the detector signal; (f) a housing for containing at least the laser, the partially reflecting surface, and the optical element, the housing being configured to prevent escape of stray radiation into the cab and to permit air from the cab to continuously circulate through the external cavity region for analysis; and (g) means for driving the laser (e.g., electrical or optical). A method is provided for measuring concentration of ethyl alcohol vapors in a vehicle employing the on-board sensor. The method comprises: (1) sensing any ethyl alcohol vapors in the cab by the on-board sensor; and (2) providing a signal indicative of presence of any alcohol vapors.

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