Abstract: In one embodiment, an improved multi-pass cell for a long path-length spectrometer is designed to include a perturbing mirror that causes a base pattern of reflections to be repeated multiple times, where each subsequent base pattern of reflections is rotated about the axis at an angle from a prior base pattern, to circulate the base patters about the cell. The base pattern may be a Herriott cell pattern. The improved multi-pass cell may be constructed with a concave front mirror centered along an axis of the cell, and a concave back mirror centered along the axis and facing the front mirror. The perturbing mirror may be centered along the axis, facing the front mirror and located at a perturbing mirror spacing in front of the back mirror or behind the back mirror, depending on the implementation.

Abstract: A cross-road motor vehicle exhaust gas analyzer uses tunable infrared laser differential absorption spectroscopy incorporating photon infrared detection to determine the absolute fractional absorption of a laser by the gaseous medium. Spectroscopic constants of the gaseous species of interest are applied to the absolute fractional absorption to calculate the pertinent absolute column densities. In addition to a laser that sweeps across one or more absorption line of an component of interest, the system of the invention includes a laser source tunable over an absorption line of a reference species; the calculated column density of the reference species is used to normalize the concentration of the component of interest to the fuel consumption rate of the motor vehicle.

Abstract: A device that provides reconfigurable optical interconnections of multiple ata channels that have applications in highly parallel computers. The device utilizes an array of optical switches which direct a set of optical beams toward any one of a selection of holograms and each hologram when selected deflects the input beams toward a detector.