Abstract: A gas cell is provided for detection of trace gases via intracavity laser spectroscopy. The gas cell comprises a gas cell body having a long body axis, an interior hollow portion along the long body axis, and two end portions, each end portion having two opposed surfaces, one surface of each the end portion cut to an angle with respect to the long body axis and including a laser-transparent window on each face defining ends of the interior hollow portion. The angle is dependent on operating wavelength of the spectrometer and refractive index of the window material at the operating wavelength. Each end portion is provided with a gas line connection in the proximity of the opposed surface, one gas line for introducing a sample gas into the interior hollow portion and the other gas line for exhausting the sample gas from the interior portion. Further, a gas cell holder is provided for supporting and positioning the gas cell.

Abstract: In accordance with the present invention, a high-resolution, compact spectrometer is provided for dispersing wavelengths .lambda. of an incoming beam for detection by a detector. The spectrometer comprises: (a) an entrance slit through which the incoming beam passes; (b) a first mirror for collimating the beam from the entrance slit; (c) a first reflectance grating for dispersing the collimated beam to form a beam having a spectral intensity distribution, the first reflectance grating having a number of grooves N.sub.1 ; (d) a second reflectance grating for further dispersing the collimated beam, the second reflectance grating having a number of grooves N.sub.2 ; and (e) a second mirror for focusing the collimated and dispersed beam, wherein the spectrometer has a substantially symmetrical construction. The symmetrical construction of the spectrometer doubles the resolution and dispersion of the gratings.

Abstract: On-board ILS sensors for detecting illegal drugs and based on intracavity laser spectroscopy (ILS) are provided for detecting the presence of drugs and their metabolized by-product vapors in an enclosed space, such as 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.