Dr. Keith Ruxton Profile

Dr. Keith Ruxton

at M Squared Lasers Ltd

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Publications (8)

Proceedings Article | 10 May 2018 Paper

Detection and identification of chemical warfare agents using mid wave infrared active hyperspectral imaging

Keith Ruxton, C. Robin Head, Rhea Clewes, Sarah Marchant, Nils Hempler, Graeme P. Malcolm, Gareth Maker

Proceedings Volume 10629, 1062904 (2018) https://doi.org/10.1117/12.2302519

KEYWORDS: Mid-IR, Chemical weapons, Absorption, Contamination, Optical parametric oscillators, Spatial resolution, Absorption spectroscopy, Hyperspectral sensing, Chemical detection, Hazard analysis

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Proceedings Article | 10 June 2014 Paper

Hyperspectral imaging using novel LWIR OPO for hazardous material detection and identification

Keith Ruxton, Gordon Robertson, Bill Miller, Graeme P. Malcolm, Gareth Maker

Proceedings Volume 9073, 90730L (2014) https://doi.org/10.1117/12.2050560

KEYWORDS: Optical parametric oscillators, Long wavelength infrared, Absorption, Hyperspectral imaging, Mirrors, Mid-IR, Infrared spectroscopy, Infrared imaging, Beam splitters, Absorption spectroscopy

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Proceedings Article | 29 May 2013 Paper

Mid-wave infrared hyperspectral imaging of unknown chemical warfare agents

Rhea Clewes, Chris Howle, Jason Guicheteau, Darren Emge, Keith Ruxton, Gordon Robertson, William Miller, Graeme Malcolm, Gareth Maker

Proceedings Volume 8710, 871002 (2013) https://doi.org/10.1117/12.2017868

KEYWORDS: Mid-IR, Sensors, Short wave infrared radiation, Liquids, Metals, Absorption, Infrared spectroscopy, Mirrors, Optical parametric oscillators

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Proceedings Article | 29 May 2013 Paper

Hazardous material analysis using mid-wave infrared hyperspectral imaging techniques

K. Ruxton, G. Robertson, B. Miller, G. P. Malcolm, G. Maker

Proceedings Volume 8710, 87100L (2013) https://doi.org/10.1117/12.2017865

KEYWORDS: Optical parametric oscillators, Absorption, Infrared imaging, Mid-IR, Mirrors, Hyperspectral imaging, Infrared spectroscopy, Short wave infrared radiation, Electronics, Imaging systems

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Proceedings Article | 8 November 2012 Paper

Concentration measurements of complex mixtures of broadband absorbers by widely tunable optical parametric oscillator laser spectroscopy

K. Ruxton, N. Macleod, D. Weidmann, G. P. Malcolm, G. Maker

Proceedings Volume 8537, 85370I (2012) https://doi.org/10.1117/12.971184

KEYWORDS: Absorption, Optical parametric oscillators, Mid-IR, Bioalcohols, Sensors, Calibration, Algorithm development, Mirrors, Laser spectroscopy, Infrared spectroscopy

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The ability to obtain accurate vapour parameter information from a compound’s absorption spectrum is an essential data processing application in order to quantify the presence of an absorber. Concentration measurements can be required for a variety of applications including environmental monitoring, pipeline leak detection, surface contamination and breath analysis. This work demonstrates sensitive concentration measurements of complex mixtures of volatile organic compounds (VOCs) using broadly tunable mid wave infrared (MWIR) laser spectroscopy. Due to the high absorption cross-sections, the MWIR spectral region is ideal to carry out sensitive concentration measurements of VOCs by tunable laser absorption spectroscopy (TLAS) methods. Absorption spectra of mixtures of VOCs were recorded using a MWIR optical parametric oscillator (OPO), with a tuning range covering 2.5 μm to 3.7 μm. The output of the MWIR OPO was coupled to a multi-pass astigmatic Herriott gas cell, maintained at atmospheric pressure that can provide up to 210 m of absorption path length, with the transmission output from the cell being monitored by a detector. The resulting spectra were processed by a concentration retrieval algorithm derived from the optimum estimation method, taking into account both multiple broadband absorbers and interfering molecules that exhibit narrow multi-line absorption features. In order to demonstrate the feasibility of the concentration measurements and assess the capability of the spectral processor, experiments were conducted on calibrated VOCs vapour mixtures flowing through the spectroscopic cell with concentrations ranging from parts per billion (ppb) to parts per million (ppm). This work represents as a first step in an effort to develop and apply a similar concentration fitting algorithm to hyperspectral images in order to provide concentration maps of the spatial distribution of multi-species vapours. The reported functionality of the novel fitting algorithm makes it a valuable addition to the existing data processing tools for parameter information recovery from recorded absorption data.

Proceedings Article | 30 October 2012 Paper

Infrared hyperspectral imaging for chemical vapour detection

K. Ruxton, G. Robertson, W. Miller, G.P. Malcolm, G. Maker, C. Howle

Proceedings Volume 8546, 85460K (2012) https://doi.org/10.1117/12.975057

KEYWORDS: Absorption, Mid-IR, Optical parametric oscillators, Infrared imaging, Hyperspectral imaging, Mirrors, Short wave infrared radiation, Infrared spectroscopy, Image processing

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Proceedings Article | 30 October 2012 Paper

Mid-infrared hyperspectral imaging for the detection of explosive compounds

K. Ruxton, G. Robertson, W. Miller, G.P. Malcolm, G. Maker

Proceedings Volume 8546, 85460V (2012) https://doi.org/10.1117/12.971185

KEYWORDS: Mid-IR, Optical parametric oscillators, Explosives, Absorption, Hyperspectral imaging, Explosives detection, Mirrors, Infrared spectroscopy, Electronics, Prototyping

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Active hyperspectral imaging is a valuable tool in a wide range of applications. A developing market is the detection and identification of energetic compounds through analysis of the resulting absorption spectrum. This work presents a selection of results from a prototype mid-infrared (MWIR) hyperspectral imaging instrument that has successfully been used for compound detection at a range of standoff distances. Active hyperspectral imaging utilises a broadly tunable laser source to illuminate the scene with light over a range of wavelengths. While there are a number of illumination methods, this work illuminates the scene by raster scanning the laser beam using a pair of galvanometric mirrors. The resulting backscattered light from the scene is collected by the same mirrors and directed and focussed onto a suitable single-point detector, where the image is constructed pixel by pixel. The imaging instrument that was developed in this work is based around a MWIR optical parametric oscillator (OPO) source with broad tunability, operating at 2.6 μm to 3.7 μm. Due to material handling procedures associated with explosive compounds, experimental work was undertaken initially using simulant compounds. A second set of compounds that was tested alongside the simulant compounds is a range of confusion compounds. By having the broad wavelength tunability of the OPO, extended absorption spectra of the compounds could be obtained to aid in compound identification. The prototype imager instrument has successfully been used to record the absorption spectra for a range of compounds from the simulant and confusion sets and current work is now investigating actual explosive compounds. The authors see a very promising outlook for the MWIR hyperspectral imager. From an applications point of view this format of imaging instrument could be used for a range of standoff, improvised explosive device (IED) detection applications and potential incident scene forensic investigation.

Proceedings Article | 5 October 2009 Paper

Recent advance in tunable diode laser spectroscopy with background RAM nulling for industrial applications

Keith Ruxton, Arup Lal Chakraborty, Andrew McGettrick, Kevin Duffin, Walter Johnstone, George Stewart

Proceedings Volume 7503, 750313 (2009) https://doi.org/10.1117/12.833000

KEYWORDS: Absorption, Modulation, Spectroscopy, Nulling interferometry, Lenses, Tunable diode lasers, Laser spectroscopy, Near infrared, Resonators, Phase shift keying

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Showing 5 of 8 publications

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