Mr. William Miller Profile

William Miller

at LedNorth Ltd

SPIE Involvement:

Author

Publications (7)

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 | 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

Stand-off spectroscopy for the detection of chemical warfare agents

Rhea Clewes, Chris Howle, David J. Stothard, Malcolm Dunn, Gordon Robertson, William Miller, Graeme Malcolm, Gareth Maker, Rick Cox, Brad Williams, Matt Russell

Proceedings Volume 8546, 85460X (2012) https://doi.org/10.1117/12.974574

KEYWORDS: Raman spectroscopy, Photons, Imaging systems, Sensors, Spectroscopy, Liquids, Blistering agents, Optical parametric oscillators, Crystals

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The most desirable configuration for detection of toxic chemicals utilises the maximum distance between detector and hazard. This approach minimises the contamination of equipment or personnel. Where the target chemical is an involatile liquid, indirect detection of the liquid contamination is made difficult by inherently low vapour pressure. In this instance, direct detection of the chemical hazard is the best approach. Recent technology developments have allowed spectroscopic systems to provide multiple options for the stand-off detection of involatile chemical warfare agents (CWAs). Two different stand-off spectroscopic systems, based upon IR absorption and Raman spectroscopic techniques are described here. The Negative Contrast Imager (NCI) is based upon an optical parametric oscillator (OPO) source comprising a Q-switched intracavity MgO:PPLN crystal. This crystal has a fanned grating design and wavelength tuning is achieved by translating the PPLN crystal within the 1064 nm pump beam. This approach enables the production of shortwave and midwave IR radiation (1.5 – 1.8 μm and 2.6 – 3.8 μm, respectively), which is scanned across the scene of interest. Target materials that have an absorption feature commensurate with the wavelength of incoming radiation reduce the intensity of returned signal, resulting in dark pixels in the acquired image. This method enables location and classification of the target material. Stand-off Raman spectroscopy allows target chemicals to be identified at range through comparison of the acquired signature relative to a spectral database. In this work, we used a Raman system based upon a 1047 nm Nd:YLF laser source and a proprietary InGaAsP camera system. Utilisation of a longer excitation wavelength than most conventional stand-off detection systems (e.g. 532 or 785 nm) enables reduction of fluorescence from both the surface and the deposited chemicals, thereby revealing the Raman spectrum. NCI and Raman spectroscopy are able to detect CWAs on surfaces at distances of 2 – 10 metres and have potential to detect over longer ranges. We report the successful identification of at least 60 μl of nitrogen mustard at a distance of a 2 m and 10 m using NCI and Raman spectroscopy.

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 | 6 October 2011 Paper

Hazardous liquid detection by active hyperspectral imaging

Chris Howle, Alexander Frisby, Alastair J. McIntosh, David J. Stothard, Malcolm Dunn, Gordon Robertson, William Miller, Graeme Malcolm, Gareth Maker

Proceedings Volume 8189, 81890H (2011) https://doi.org/10.1117/12.898516

KEYWORDS: Mid-IR, Optical parametric oscillators, Mirrors, Crystals, Absorption, Liquids, Hyperspectral imaging, Short wave infrared radiation, Laser crystals, Sensors

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