Background

Tunable Absorption Spectroscopy is a common technique for measuring the concentration of certain species in a gaseous mixture. It simply provides the chemical fingerprint of components by the absorption of the light at the wavelengths which resonate with e molecules inducing vibrations and rotations. Most of these systems are large bench top instruments. There exists a need for an all-optical, wireless-compatible gas cell with extremely small footprint for the sensitive detection of multiple gases in small, inaccessible volumes, or under extreme, impervious conditions.

Description

This technology is an extremely small and robust cell in which a very small volume of gas is sampled, while maintaining high sensitivity and specificity, by combining it with:

  • Highly tunable and commercially available semiconductor lasers, such as edge emitting lasers and vertical cavity surface emitting lasers (to provide various absorption lines of one specie and to capture varies elements at once), and
  • Wavelength modulation spectroscopy (to extract high harmonics which are not affected by the 1/f noise).

Furthermore, the source and detector are both fiber-coupled allowing remote detection of gases down to ppm (and potentially to ppb) in hazardous and unfavorable conditions and enabling multiplexing of different sources for the analysis of gas mixtures absorbing in different wavelength ranges.

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Advantages
  • Optical sensors: no EMI allows safe operation (e.g. when energetic material are present)
  • Fiber based capability enables remote detection in hazardous and unfavorable conditions
  • Robust and rugged cell amenable to harsh environment, portability and field deployment
  • Miniaturized gas cell supports multiplexed and multipoint detection of gases mixtures
  • Packaged system enables embedded continuous monitoring implying lower operating cost
Potential Applications
  • Continuous, monitoring and detection of gases and mixtures thereof (e.g. headspace atmospheric balances and aging of closed systems)
  • Environmental and pollution monitoring (e.g. certify exhaust compliances, control toxic industrial gases production)
  • Forensic analysis in either chemical global threats (e.g. nerve agents), homeland security (e.g. by-products of explosives or radiological exposure) or local law enforcements in drug/alcohol screenings (e.g. breath analyzer)
  • Agronomic/rural developments (e.g. crop surveillance) and ecosystems by monitoring greenhouse gases
  • Biomedical: markers for diseases
  • Mitigation and remediation of local and global accidents (e.g. monitor CO2/O2 breath analysis)
  • Low cost replacement of house smoke detectors
Development Status

A number of prototypes have accurately detected a few common gases. Planned experiments will test for a wider range of gases. Patent applications have been filed covering this technology.

Reference Number
27313
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