Massachusetts Institute of Technology

Jonathan Ashcom

Sumanth Kaushik

Eric R Statz

Alan E DeCew, Jr

A method and apparatus used for detecting gaseous chemicals. The method and apparatus use an interferometer to filter received light by wavelength, creating an image only using light with wavelengths that are affected by the presence of a gaseous chemical. A reference image composed of light with wavelengths unaffected by the presence of a gaseous chemical is also created and used as a reference. A gaseous chemical is detected where the ratio of the intensity of the two images changes. Despite the high spectral resolution of the filter, the system can operate with a very wide field of view.

Wide field of view narrowband imaging filter technology

A gas detector includes a receiver configured to receive light from a light source through gas, the light source having a bandwidth on the order of an absorption linewidth of the gas, the receiver including at least a first etalon having a transmission bandwidth on the order of the absorption linewidth of the gas, the transmission bandwidth of the first etalon being substantially smaller than the bandwidth of the light source. The gas detector further includes a first detector for detecting light transmitted through the first etalon, a second detector for detecting light reflected from the first etalon, and a processor that determines the quantity of gas based on the detected transmitted and reflected light. The gas detector can further include a second etalon with a transmission bandwidth approximately equal and adjacent to the transmission bandwidth of the first etalon. Alternatively, the gas detector can include a beam separator that separates the light from the light source into a first beam and a second beam, with a small deflection angle between the first beam and the second beam, thereby modifying the effective thickness of a single optical element for each beam and forming the first and second etalon in the optical element.

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Cambridge, MA, United States of America

Jonathan Ashcom