Technology

Laser
Dispersion
Spectroscopy

A revolution in gas sensing intelligence

Reliable measurements for challenging conditions

Combining the use of advanced mid infrared lasers with the patented Laser Dispersion Spectroscopy (LDS) technique for high-resolution chemical analysis, MIRICO’s instruments revolutionise gas sensing.

MIRICO’s instruments offer the unique combination of real time analysis with high sensitivity, accuracy and stability, a wide dynamic range and the ability to perform remote sensing in inclement conditions.

Laser Dispersion Spectroscopy

Laser Dispersion Spectroscopy (LDS) takes a completely new approach to optical gas sensing. Traditional optical sensing systems rely on measuring the optical power of transmitted light as function of wavelength to infer molecular concentrations. In contrast, with LDS the differential phase change induced by molecules in the line of sight is measured and this brings unique sensing advantages:

Optical transmission sensing systems measure small signal changes (molecular absorption) on top of a large background (total optical power arriving at the detector). Such a measurement is subject to misinterpreted transmission changes and baseline optical power variations, both of which affect the overall sensitivity and stability of concentration measurements. The exponential nature of molecular absorption also severely limits the dynamic rage of the concentration measurement.

In contrast, MIRICO’s patented LDS technology measures optical molecular dispersion via a differential phase measurement of the light. This eliminates background/baseline and most of the common noise associated to long atmospheric paths (turbulence). The linearity of the optical dispersion also enables measurement across a very wide concentration dynamic range of up to five orders of magnitudes as well as increased selectivity.

Critically, as the measured signal is mostly independent of the received optical power, LDS is highly resilient to adverse environmental conditions such as rain, fog, snow or dust, providing reliable measurements in real time.

The mid-IR advantage

The mid-IR spectral region is where most molecules possess the strongest fundamental rovibrational bands, which are not accessible using conventional near-IR spectroscopy. Probing the mid-IR bands with LDS means MIRICO's instruments achieve higher sensitivity.
The mid-IR offers two wide atmospheric spectral windows with minimal water vapour interference enabling high precision and versatile molecular sensing. The reduced scattering at longer wavelength also contributes to make the mid-IR the optimal region for demanding gas phase chemical sensing applications.
The advent of semiconductor lasers capable of emitting light in the mid-IR region has MIRICO leads in transforming the developments in mid-IR photonics into practical sensing MIRICO leads in transforming the developments in mid-IR photonics into practical sensing systems and applications and takes full advantages of recent developments.