Deliverables
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.
The aim of this task was to establish a concept demonstrator optical sensor unit and integrate this into environmental monitoring to allow full characterisation and demonstration of operational capability and quantification of commercial potential.
The overall technical objective was to develop technologies relevant to rapid measurement of gas concentrations in open paths. Examples of where this might be applied, and exploited, were proposed in remote vehicle emission monitoring, and certain types of open path environmental monitoring such as at boundary fences.
At the end of the project the following have been achieved
- Software/optical and electronic technologies have been developed to allow and enhance fast measurements.
- The range of gases which can be monitored has been explored and expanded. Limitations and scope of measurement defined.
- A laboratory research spectrometer system has been developed.
- The multispecies laboratory spectrometer has been tested on a vehicle engine test bed to demonstrate the feasibility for on-board exhaust emission measurements using NIR laser technology and also to provide background knowledge as to emission levels characteristic of specific engine operating conditions.
- Cross-road test measurements have been performed on multispecies (CO and CO2) and have demonstrated successfully the rapid response of the system with measurements taken of vehicles travelling at high speed.
The market for commercial exploitation will be driven by legislation and discussions are ongoing at European and International levels. Despite limitations due to the difficulty of measuring nitric oxide and total hydrocarbons using NIR diode laser technology we are engaged in discussions with companies in the UK and US regarding combining NIR diode laser technology with other approaches.
Dissemination has currently been through conference presentations and peer-reviewed scientific journals.
Original research objectives:
To select the most promising application for a NIR-DLS gas sensor to be used for in-line monitoring and control of processes in the consumer products industry. A laboratory feasibility demonstrator has been built to experimentally verify the potential of the selected application.
Deliverables:
- Developed lab-scale equipment (multi-pass cell, dedicated NIR-DLS spectrometer, test set-up) to investigate the feasibility of non-destructive measurement of gas phase compositions at the ppm level inside glass enclosures.
- A task report discussing the aforementioned feasibility and containing specifications.
Outcome:
- Multi-pass optics adapted to monitor the gas atmosphere inside glass enclosures have been designed within the consortium and built by an external company.
- A NIR-DLS spectrometer to measure the chosen gases has been designed and built. Required rework on the spectrometer has been successfully completed.
- A set-up to test instrument performance has been built: variables include Pressure range and Concentration range. A series evaluation experiments have been performed.
Conclusions:
The approach has been shown feasible in principle. Detailed studies of performance and process insight are in progress.
In this area it was proposed to undertake assessment of the underpinning science, and (in collaboration with partners) the scope and potential of NIRLD technology for monitoring and enhancement of process control of CVD processes.
Up to mid term the feasibility of in -situ process monitoring with NIRLD spectrometry has been successfully assessed and demonstrated.
Post Mid term the work was extended to full end user feasibility demonstration, incorporating advanced designs and capabilities in the trials (e.g. multi species and multi-point monitoring).
Demonstration of "additional process insight" will be a key milestone in assessing added value to potential customers and commercial potential
The new techniques and equipment developed are to be promoted externally.
A follow on project (Framwork 6) extending this work further in the Photovolatic area, has been approved.
Design and construction of a laboratory demonstration spectrometer based on free space optical design with the goal to achieve a significant performance enhancement in a multi-component, modular configuration has been successfully made. The spectrometer, even though designed for measurement of traces of contaminating gases in the ultra pure gas feed lines to semiconductor fabrication, will have a number of additional applications in production processes where measurements and subsequent control of very low concentrations of specific gases will improve production yield and reduce contamination. Typical gases are O2, H2O and H2S.
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