The aim of this work was to explore and evaluate the technologies available, and projected to be developed, targeting at achieving a step change in performance, size, cost, and applications and to evaluate the potential capabilities of next generation optical sensors.
Novel/advanced designs of NIRLD spectrometers targeted at portability and high sensitivity have been explored. Miniaturisation of all major components, optical, mechanical and electronic has been studied, and a completely new miniature design using current DFB lasers has been completed. Assessment of current technologies for realisation of miniature electronics has confirmed that a miniature version of a TDL instrument can be manufactured at a significantly lower cost without sacrificing performance.
Studies into low volume cell designs have been undertaken.
In the area of high sensitivity, cavity-enhanced approaches have been developed and instruments. These approaches enable detection limits in the low ppb and ppt range and have been demonstrated for NO2 and CO2 isotope detection. New lasers and new laser designs have been considered and selectively acquired. These include long wavelength DFBs, new VCSELs. Quantum cascade lasers have also been investigated.
An example application for this high sensitivity technology is the analysis of trace compounds on human breath. With particular reference to ease of use, detection level capability, accuracy and precision of result. Portability and high sensitivity were established as key technical areas for advancement. A laboratory feasibility assessment instrument has been developed which can measure 13CO2/12CO2 ratios in human breath. This is especially valuable for the metabolism of isotopically labelled drugs.