Aerodyne Research, Inc.

US Government As Represented by the Secretary of the Army

J Barry McManus

H John Caulfield

David D Nelson, Jr

Charles E Kolb

Mark Stuart Zahniser

Roger S Putnam

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.

Optical multi-pass cell for long path-length spectroscopy

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.

Laser system for cross-road measurement of motor vehicle exhaust gases

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.

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Arlington, MA, United States of America

J Barry McManus