Laser Isotope Ratiometer

Laser Isotope Ratiometer2019-01-10T11:32:31+00:00
Technology Overview

The Laser Isotope Ratiometer (LIR) delivers a novel approach to the measurement of stable isotope ratios of a given molecule. The instrument is designed to offer high precision, real-time measurements in a compact and robust package. Furthermore, the system is equipped with an on-board calibration system for autonomous operation and enhanced stability and accuracy in a simple package. The LIR brings simplicity to stable isotope analysis, whether in the field or in a laboratory environment. The instrument’s design originated as part of a European Space Agency programme to demonstrate the LIR, and the design offers compactness, robustness and precision without the need for a skilled operator or consumables.

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Our Approach in Brief

  • Continuous calibration of measured sample to known reference standard
  • High accuracy and reliability of data
  • Low drift system with permanent calibration cell
  • Lasers chosen to target specific isotopologues that exhibit equal temperature dependance
  • System sample immune to temperature variations that would otherwise have very significant effects on accuracy and precision
  • Designed with field deployment in mind to maintain precision outdoors

Molecules exhibit the strongest fundamental ro-vibration bands, and the region exhibits wide spectral windows, which enables:

  • High sensitivity achieved without the need for complex cavity enhancements
  • Operating in the atmospheric window with minimal interference from water vapour
  • Enhanced accuracy, stability and precision

How it Works

Two lasers of wavelength λ1 (blue) and λ2, (red) probe 13CO2 and 12CO2. The wavelengths are selected for optimum measurements of the isotopes and equal temperature dependence. Lasers probe the gas sample, at the same time a reference mixture. A fast optical switch flicks the beam between the gas sample probe and reference chamber probe at a rate greater than 16 KHz. Detectors measure the beams, λ1 and λ2 measuring the reference channel and sample channel simultaneously. Signal processing then calculates concentration profiles and the stable isotope ratio is derived.

The Mid-IR

 MIRICO’s Laser Isotope Ratiometer approach takes full advantage of such lasers. Carefully selected wavelengths of the dual laser system are chosen in the mid-IR spectral region, where most molecules exhibit their strongest fundamental ro-vibrational bands. This enables MIRICO to achieve very high sensitivity without the need for complex cavity enhancement required in other approaches. In addition, the mid-IR offers two wide spectral windows, enabling molecular sensing with minimal spectral interference (primarily from water vapour). This allows the LIR to offer high performance without complexity, making it ideal for taking measurements to the field.

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