See the LGR Advantage

the LGR advantage: the technology

Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS)

All LGR analyzers utilize a unique laser absorption technology called Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS). This LGR-patented technique offers superior performance, value and reliability compared to cavity ringdown spectroscopy (CRDS).

Cavity enhanced absorption was first developed as an ultra-sensitive detection method by LGR founder Anthony O'Keefe in 1988 (Review of Scientific Instruments (ISSN 0034-6748), vol. 59, Dec. 1988, p. 2544-2551) in the form of cavity ringdown spectroscopy (CRDS). While innovative, this first-generation technique requires sub-nanometer alignment of its internal optics, which translates directly into limitations in terms of high cost, reliability, and vulnerability to vibrations and temperature/pressure changes.

To overcome these drawbacks, scientists at LGR developed, and subsequently patented, a fourth-generation cavity enhanced laser absorption technology called OA-ICOS. This approach delivers superior performance, yet is orders-of-magnitude less sensitive to internal alignment of components and to variations in local temperature and pressure. As a result, OA-ICOS is ideal for use in commercial instruments for even the most demanding applications in remote locations.

The inherent advantages of OA-ICOS technology make LGR trace gas and stable isotope analyzers the best choice, whatever the application.

  • Parts-Per-Billion (ppb) Precision: OA-ICOS avoids the expense and vulnerability of a sub-nanometer opto-mechanical setup. This enables it to easily deliver parts-per-billion precision (or better) quickly and in an easy-to-use package.
  • Wider Dynamic Range: OA-ICOS directly measures absorption rather than only a cavity decay time. Therefore it offers a linear response over a significantly wider dynamic range than conventional CRDS (i.e. up to 100% mole fraction for some gases).
  • Best Performance: OA-ICOS analyzer performance is not dependent on hyper-critical optical alignment, whereas older cavity-based techniques (e.g., CRDS) require sub-nanometer optical component alignment. This makes these older techniques very vulnerable to degraded performance due to vibrations, small physical shocks, and changes in temperature and pressure.
  • Field Serviced: OA-ICOS performance is orders of magnitude less sensitive to internal alignment, so our rugged instruments are robust and reliable. And designed with simplicity in mind, in the rare instance that repair is necessary; LGR instruments may be easily serviced on site by anyone.
  • Lower Manufacturing Cost: OA-ICOS analyzer performance is not dependent on hyper-critical optical alignment, whereas older, conventional CRDS techniques require sub-nanometer optical component alignment. This necessitates the use of expensive electro-mechanical components and complex feedback loops as well as very time-consuming cleanroom assembly and elaborate testing.
  • Better Value: OA-ICOS analyzer performance is completely unaffected by any minor shifts in optical alignment. This enables the use of simpler, lower-cost components and fewer feedback control systems, as well as simplifying our assembly process.
  • Minimal Downtime: OA-ICOS technology does not require ultra-precise optical alignment. This means that a minimally trained user can easily remove a cavity mirror, if necessary, and then clean and replace it in only minutes, with no impact on performance or expensive returns to the factory.
Benefits Uses