EngD Yearbook - Conference Abstracts 2011 Programme 2010/2011, ENGINEERING DOCTORATECENTRE! PARTNERSHIPBETWEEN HERIOT1WATT,!ST ANDREWS,!STRATHCLYDE,! AND!GLASGOW UNIVERSITIES! CONFERENCEPROGRAM

ConferenceProgramme 2010/2011

ENGINEERING DOCTORATE CENTRE

PARTNERSHIP BETWEEN

HERIOT-‐WATT, ST ANDREWS, STRATHCLYDE,

AND GLASGOW

UNIVERSITIES

CONFERENCEPROGRAMME 2010/2011

Engineering Doctorate Optics & Photonics Technologies

www.engd.hw.ac.uk

Welcome

Welcome to the 2011 annual conference of the Industrial Doctorate Centre in Optics and Photonics Technologies: a collaboration between Heriot-‐Watt, Glasgow, Strathclyde and St Andrews Universities.

Optics and photonics is a cross-‐disciplinary set of sciences and technologies that enable, underpin and interact with a vast range of sciences and technologies that involve the understanding, exploitation and control of light. Recent decades have witnessed optics and photonics impacting more and more technology areas and disciplines. The increased use of photonics in computing and communications are illustrative examples; in fact the term ‘photonics’ was introduced as an indication that those functions that were previously executed using electronics are increasingly achieved using photons. Optics and photonics pervades life; from overt use in imaging, illumination and manufacturing, through its exploitation by the wider scientific community, for example, in medical assessment and treatment, environmental monitoring and metrology; to fundamental scientific research in quantum and classical optics. In fact there is barely an aspect of modern life, and the industrial community integrated with it, that is not dependent upon optical and photonic technologies.

The field of optics and photonics is diverse and interdisciplinary in nature and the universities underpinning this IDC are perhaps unique in having the strength in depth and breadth to support research across the full range of optical and photonic technologies. Research ranges from blue-‐skies, potentially transformative research; for example on Bose-‐Einstein condensates, negative refraction and nano-‐photonics; through developing technologies that have recently become appropriate for commercialisation, such as quantum communication to many examples of applied research; some based on earlier fundamental research within these institutions. It is this latter category that is particularly pertinent for Knowledge Transfer between companies and universities and is particularly well represented in the above list.

The new IDC is supported by 90 academics distributed between Heriot-‐Watt, St Andrews, Strathclyde and Glasgow Universities and more than 30 companies ranging from start-‐ups to multinationals. This diverse collaboration is united in a common goal to bring cutting edge research in optics and photonics to tomorrow’s products. Realising the potential Impacts of this collaboration is as important to academics seeking future research opportunities as it is to companies seeking to maintaining a competitive advantage through the excellence of their products.

Our Research Engineers will be making presentations today on their recent Engineering-‐Doctorate research. Research projects are directed by the company and are a close collaboration with a university research group -‐ normally whilst being embedded directly within the company. The challenge of satisfying the twin demands of academic research and commercial relevance are not inconsiderable for our Research Engineers, but they speak with pride of the rewards of making a tangible difference to their companies through the application of their cutting edge research. Since many of our Research Engineers go on to be employed by their host company it seems that their contributions and the technical and business skills they acquire are equally valued by the companies.

Professor Andy Harvey

Director of Industrial Doctorate Centre in Optics and Photonics Technologies

The support of the following sponsor companies is gratefully acknowledged:

List of companies alphabetically

BAE Systems BCF Designs British Energy Cascade Technologies Edinburgh Instruments Gooch and Housego Holoxia MCS MEMSSTAR M-‐Solv National Physical Laboratory NCR Optos plc OptoSci PowerPhotonics Renishaw Rofin-‐Sinar Roke Manor Rolls-‐Royce Rutherford Appleton Laboratory SeeByte Selex Galileo STFC ST Microelectronics Taylor Hobson Ltd TES Electronic Solutions Thales Optronics Trumpf UKATC

Sponsors benefit from research on a topic of direct relevant to their business, conducted by outstanding graduates and have access to world-‐leading academics and research facilities. If your company would consider sponsoring an EngD project, please contact the EngD Centre as per details below.

EngD Centre Optics and Photonics Technologies www.engd.hw.ac.uk

E-‐mail: [email protected]

EngD Research Engineers 2010/2011

Year 1

Name Sponsor Company

Marcus Ardron Renishaw Anthony Corcoran Optos Will Cochrane STFC Oliver Daniell Seebyte Christopher Dickson Thales UK John Molloy National Physical Laboratory Eoin Murphy BAE Systems Mathieu Rayer Taylor Hobson Ltd Joseph Thom National Physical Laboratory

Year 2


Robert Campbell Cascade Technologies Matt Currie PowerPhotonics Ben Fulford Rofin-‐ Sinar Ryan John BAE Systems Michael Leach Roke Manor Mark McCallum Edinburgh Instruments Marcus Perry British Energy Year 3


Margaret Anayaegbu TES Electronic Solutions Jochen Deile Trumpf James Downing ST Microelectronics Daniel Drysdale MEMSSTAR Catherine Fitzpatrick National Physical Laboratory Brian Flemming Selex Galileo Viktor Granson Trumpf Javid Khan Holoxia Mhairi Martin BAE Systems Lucy Williamson Hodge Rutherford Appleton Laboratory

EngD Research Engineers 2010/2011

Year 4


James Bain Rolls-‐Royce James Beedell Selex Galileo Yves Lacrotte Renishaw Thomas Legg Gooch and Housego Andrew White Selex Galileo

Year 5


Scott Colston NCR Stephan Kloss Renishaw Gordon McKenzie BCF Designs Martin Mehta Virtual Interconnect Suzanne Costello (nee Millar) MCS Ltd Alan Proudfoot BAE Systems Veronika Tsatourian NPL Gerald Wong Selex Galileo Year 6+ Name Sponsor Company

Paul Black Cascade Technologies Roger Fenske Edinburgh Instruments Patrick Harding Thales Optronics Paul Harrison Robert Ibbotson Rutherford Appleton Laboratory

Poster Abstracts

(listed alphabetically)

EngD Conference Poster/Presentation Abstract 2011

Project Title: Laser manufacture of phase grating on metal surfaces Research Engineer: Marcus Ardron Sponsor Company: Renishaw PLC Host University: Heriot Watt University Academic Supervisor: Prof Duncan Hand, Heriot Watt University Industrial Supervisor: Dr Nick Weston, Renishaw PLC E-‐mail: [email protected] Registration Date: Sept 2010 Project Abstract Diffraction gratings are used for the metrology element in many designs of linear and rotary encoders, especially mid or fine period products. These gratings can be as long as 50m in large assembly machines, and have grating period as small as 500nm for very high accuracy applications; 20μm is very common in mid-‐accuracy designs and 8µm in high accuracy offerings. As a successful producer of mid-‐accuracy linear and rotary encoders, Renishaw PLC would like to investigate economic production of fine period gratings to suit the high accuracy requirements of modern industry, especially manufacturers of electronics and flat screen displays. Experiments have shown a smooth sinusoidal surface profile can be achieved by sequentially melting regions of a polished metal surface with a frequency tripled Nd:YAG laser emitting at 355nm. UV light is reasonably well absorbed by stainless steel or nickel and 30ns pulses enable local melting of metals without reaching ablation regimes. It has been demonstrated that the phase depth of the undulating surface can be controlled well enough to realize an effective phase grating. Three mechanisms seem to contribute to the surface movement of the molten material: thermo-‐capillary motion, chemi-‐capillary motion and surface tension. All three act simultaneously to provide the force needed:-‐ primarily, it is surface tension gradient that is proportional to temperature gradient and related to the concentration of surface active elements in the melt-‐pool. By identifying and understanding the effects of material elemental concentrations, local atmosphere and laser pulse energy we are seeking a stable combination for simple, clean and dry production of long lengths of phase grating.


Project Title: Optical Coherence Tomography in the Retinal Periphery Research Engineer: Anthony Corcoran Sponsor Company: Optos Plc Host University: Heriot Watt University Academic Supervisor: Prof Andrew Harvey, Heriot Watt University Industrial Supervisor: Dr Jano Van Hemert, Optos Plc E-‐mail: [email protected] Registration Date: 10/01/2011 Project Abstract Ever since the advent of optical coherence tomography (OCT) two decades ago, the clinical demand and usefulness of OCT has exploded. Over this time, OCT has evolved into a wide range of applications, from ophthalmology to cardiac surgery and even drug effectiveness monitoring. As OCT is still a relatively young innovation-‐rich technology, Optos Plc, a Scottish company that specialises in ultra-‐wide-‐field scanning laser ophthalmology (SLO), aim to bring their unique expertise to solve some of the significant challenges of OCT. Existing commercial ophthalmic-‐OCT systems are typically limited to imaging only a 6mm2 spot and have 3D exposure times as high as 5 seconds; however, the surface area of the retina is 1094mm2; therefore, 96.7% of the retina is left unseen. This limitation means diseases like retinal detachment, AMD and diabetic retinopathy may go undetected until vision is compromised. Also, rapid eye movement deteriorates any ophthalmic image with an exposure time longer than a third of a second; therefore, OCT is currently providing images with a quality far below its potential. The objective of my thesis is to use the unique architecture of the Optos SLO engine to overcome the many problems of OCT. The problems that Optos have an advantage solving include both the limiting aperture of the pupil restricting imaging of the periphery and the variable optical path difference induced by the curvature of the pupil. More typical constraints that will be attempted to be alleviated include the speed and sensitivity of the detection camera, along with the speed and flexibility of MEMS scanning components. Work for Optos up till now includes developing a 1D spectral domain OCT system that could spatially map the interfaces of multiple glass slides pressed together.


Project Title: New Pick-‐Off Systems for Multi-‐Object Observations within Astronomical Instrumentation Research Engineer: Will Cochrane Sponsor Company: UK Astronomy Technology Centre (UK ATC) Host University: Heriot Watt University Academic Supervisor: Dr. Xichun Luo Heriot Watt University, Dr. Theodore Lim Heriot Watt University Industrial Supervisor: Dr. Hermine Schnetler, UK Astronomy Technology Centre (UK ATC) E-‐mail: [email protected]; [email protected] Registration Date: 01/07/2010 Project Abstract Current Multi Object Spectrometers (MOS) and Integral Field Units (IFUs) rely on robotic arms or mask plates for choosing objects to study. Mask plates are inflexible and can need 24 hours to be configured. Robotic arms limit the amount of objects that can be observed simultaneously. Examples being FORS that can view 19 objects, MX 32 objects and MEFOS 30 objects. It is proposed that micro autonomous robots can be used that have the advantages and none of the disadvantages of both systems. Currently the available micro autonomous robots are not capable of the positional accuracy required for astronomy.

There are also fibre fed MOS systems that allow for more objects to be observed simultaneously. However these suffer from poor transmission throughput in comparison to slit spectrometry. Due to the capabilities of plasmonics guiding light below the diffraction limit, it is proposed that the development of plasmonic lenses in combination with a fibre fed MOS could improve the quality of light that is collected during observations.

A new MOS system that uses a programmable slit mask is being investigated. Liquid crystal technology has shown that in a clear state ~50% of light can be transmitted. This could be improved through the altercations of current technology and possibly the addition of a liquid lens layer in combination with the liquid crystal technology.

It is the aims of this project to develop three multi object pick-‐off systems. One that utilizes micro autonomous robots with pick-‐off mirrors. A fibre fed system that incorporates plasmonics to improve the quality of light being collected and a programmable mask based on liquid crystal technology.

Currently a micro autonomous robot has been developed that is being tested and characterized. Research has also begun on the underlying principles behind plasmonics and liquid crystals.


Project Title: Automatic Target Recognition in Imaging Sonar Research Engineer: Oliver Daniell Sponsor Company: SeeByte Host University: Heriot-‐Watt Academic Supervisor: Prof. Yvan Petillot, Heriot-‐Watt Industrial Supervisor: Dr. Scott Reed, SeeByte E-‐mail: [email protected] Registration Date: September 2010 Project Abstract Autonomous Underwater Vehicles (AUVs) are employed to assist human operators in inspecting large areas of the seafloor. SeeByte currently produces software for monitoring pipelines in oilfields and detecting mines on the seafloor. These tasks increasingly require the AUV to be able to respond to its environment in real time. Situational awareness is provided in the medium (20m-‐100m) range by imaging sonar systems which create a “photographic” representation of the sea floor. Detection of objects in sonar images is complicated by the low resolution and high noise statistics of the sonar, as well as the physical differences between sensor types. The primary aim of this EngD is to reduce the sonar data to a sensor independent representation consisting of simple 3D shapes. This information will be used to train machine learning algorithms to classify objects (such as mines) and extract information about the object for use in adaptive mission planning. In addition, the sensor independent feature space has the potential to enable matching of unclassified and previously unseen objects between different sensors and viewpoints. Associating the same object using different sensors will be key to increasing the autonomy of current AUVs, allowing vehicles with different sensor payloads to share information intelligently and navigate using a feature map created by another AUV.


Project Title: Multimodal Sensor Integration for Moving Platforms Research Engineer: Christopher Dickson Sponsor Company: Thales UK Host University: Heriot Watt Academic Supervisor: Andrew Wallace (Heriot Watt) Industrial Supervisor: Barry Connor & Matthew Kitchin (Thales UK) E-‐mail: [email protected] Registration Date: Sep 2010 Project Abstract A reliable, accurate and informative situational awareness system is a key component of a successful military command vehicle. Ideally, such a system will classify the surrounding scene into its constituent parts, and efficiently detect and identify any object of interest (or suspicion) within a certain perimeter of the vehicle. However, for the system to be useful, it must be able to present findings to a user in an easily-‐accessible format which assists the user in completing the task to which the vehicle has been assigned. In this poster, a 3D visualisation tool for situational awareness is proposed, which integrates information from a sensor suite (consisting RGB camera, NIR camera, polarimetric IR camera, and GPS) in order to build 3D models of objects detected within the scene. These models, constructed slowly over time, will allow the user to interact with objects in the scene and aid identification tasks. To date, a literature review has been completed to gain a greater appreciation of computer vision algorithms and fusion methods, while also coding an interface to interact with the different data streams. An important aspect of the project will involve producing demonstration software in order to visually communicate the current state of the system.


Project Title: Tunable Terahertz Sources Research Engineer: John Molloy Sponsor Company: National Physical Laboratory Host University: Heriot-‐Watt Academic Supervisor: Prof A. K. Kar, Heriot-‐Watt Industrial Supervisor: Dr. M. Naftaly, National Physical Laboratory E-‐mail: [email protected] Registration Date: 20th June 2011 Project Abstract The aim of this project is to develop a milliwatt, multi-‐terahertz (THz), optical parametric oscillator (OPO), that is tunable over the frequency range 3-‐10 THz. A case for the development of such a THz laser is presented, outlining it’s desirability for the complete range of THz spectroscopy applications, over a wide variety of fields, including; non-‐destructive material testing, remote sensing and homeland security. Further detail is given on an application of particular interest, the analysis and identification of bio-‐molecular substances, pharmaceuticals and other organic compounds; as these materials have been found possess clear and distinctive molecular resonances within the THz regime. Currently available technologies, e.g. Periodically Poled Lithium Niobate (PPLN) OPOs are examined, specifically looking at their capabilities and weakness, as THZ generators. Finally a solution is proposed, to extend the frequency range available to optical parametrically generated THz radiation into the multi-‐terahertz regime, with improved beam qualities and increased power.


Project Title: Wavelength agnostic WDM Strategies for Avionic Telecommunications Research Engineer: Eoin Murphy Sponsor Company: BAE Systems Host University: University of Strathclyde Academic Supervisor: Dr Craig Michie and Prof Walter Johnstone , University of Strathclyde Industrial Supervisor: Henry White, BAE Systems E-‐mail: [email protected] Registration Date: October 2010 Project Abstract With the development of highly sophisticated sensors for aircraft the demand for network bandwidth is higher than ever. In addition any aircraft manufacturer is always keen to cut down on weight of the aircraft. A fibre optic network will fulfil both these criteria with both higher achievable bandwidths than copper and less weight for a given link length; as a result we are witnessing the beginnings of a move towards optical links on aircraft. This project researches the possibility of using Wavelength Division Multiplexing (WDM) to fully utilise fibre bandwidth in an avionic environment. This would normally be realised with the use of temperature stabilised lasers in order to overcome wavelength drift associated with the harsh environment typical of aircraft, but this adds to running costs with additional weight and power consumption. One possible solution could be to use Reflective Semiconductor Optical Amplifier (RSOA) components as amplifiers and modulators to implement WDM without the need for expensive temperature stabilisation. Some initial investigations have been carried out relating to the performance of the RSOA components over an extended temperature range and how any performance changes could affect performance of the network as whole.


Project Title: Non contact surface measurement Research Engineer: Mathieu RAYER Sponsor Company: Taylor Hobson Ltd Host University: Heriot Watt. Academic Supervisor: Ajoy Kar, Heriot Watt University Industrial Supervisor: Daniel Mansfield, Taylor Hobson Ltd E-‐mail: [email protected] Registration Date: October 2010 Project Abstract From the paper manufacturer to the defense company, today industries require sub-‐micron surface and form metrology on materials which cannot maintain their shape using contact metrology method. Hence, non contact surface metrology techniques have to be designed and implemented for all types of industries in order to maintain a constant technology growth. Using the latest progress in digital signal processing, linear image sensor and lens manufacturing capability, the chromatic confocal microscope shows great promises in the challenge of transferring non contact surface measurement from the metrology laboratory to the workshop without performances compromises. The chromatic confocal microscope is based on a classical confocal principal with each axial position associated with a unique wavelength. In order to achieve this challenge, the first step is to optimize quantitatively the design. To do so, a theoretical model of the chromatic confocal microscope has been built. For a given optical target specification (e.g. NA, Spot size) and cost, this model optimizes the design parameters. The current work effort is to apply all this theoretical work to several practical prototypes. So far, results demonstrate the possibility of significant improvement in readout frequency, dynamic range and cost.

EngD Conference 2011-‐Abstract

Project Title: Deterministic entanglement of 88Sr+ ions in a microfabricated ion trap Research Engineer: Sponsor Company: Host University: Academic Supervisor: Industrial Supervisor: E-‐mail: Registration Date:

Joseph Thom National Physical Laboratory University of Strathclyde Prof Erling Riis, University of Strathclyde Dr. Alastair Sinclair, National Physical Laboratory [email protected] September 2010

Project Abstract Ultra precise atomic clocks that use a trapped atomic ion as a reference absorber have demonstrated accuracies of approximately one second in fourteen billion years. This unprecedented metrological capability has diverse applications ranging from Global Positioning Systems (GPS) to tests of the fundamental constants. Further improvements in accuracy may be achieved through the entanglement of these ion absorbers. Entangled ion states have also been central to many of the pioneering experiments in the growing field of quantum information science. The aim of this project is to achieve deterministic entanglement of 88Sr+ ions in a microfabricated ion trap using a suitable gate operation. The subsequent step is to perform a spectroscopy experiment that demonstrates an increase in precision over the unentangled case, thereby beating the standard quantum limit and approaching the Heisenberg limit, which is the absolute limit of precision of any measurement.

Central to both of these tasks is the ability to coherently drive a narrow linewidth transition of the ion with laser light that is highly agile in phase, frequency and amplitude, and that can be switched with a fast rise time and high extinction ratio. A fibre delivery system, which incorporates Acousto-‐Optic Modulators (AOMs) and a diode laser to satisfy these requirements, is being constructed at NPL. The requisite narrow linewidth and low drift rate are inherited from an existing cavity stabilised laser in an injection lock. The AOMs are driven by an amplified signal from a Versatile Function Generator; this delivers a phase controlled and amplitude shaped signal that is directly transferred to the laser light in the modulation process, thereby providing the necessary versatility. The construction of this system is ongoing, and when complete will be an enabling apparatus for entanglement based experiments.

Presentation Abstracts

(listed alphabetically)


Project Title: Synchronisation Techniques for ECMA-‐368 Ultra-‐Wideband and DECT Wireless Systems Research Engineer: Margaret Anyaegbu Sponsor Company: TES Electronic Solutions Host University: Heriot Watt University Supervisors: Dr Cheng-‐Xiang Wang, Heriot Watt University and Mr William Berrie, TES Electronic Solutions E-‐mail: [email protected] Registration Date: September 2008 Project Abstract This presentation reports on the integration and validation of a higher layer clock synchronisation algorithm on an ECMA-‐368 Ultra-‐Wideband (UWB) FPGA platform. An existing UWB FPGA demonstration platform is enhanced by implementing a higher layer synchronisation protocol on it. The protocol includes new MLME primitives and is based on a drift-‐correcting synchronization algorithm that was developed and tested using OPNET. We observe that the drift-‐correcting algorithm performs satisfactorily and is able to achieve the desired accuracy of 100 microseconds.


Project Title: Slab thermal lens manipulation Research Engineer: James Beedell Sponsor Company: Selex Galileo Host University: Heriot Watt Univerity Academic Supervisor: Prof. Duncan Hand, Heriot Watt University Industrial Supervisor: Dr Ian Elder and Dr Sean Kudesia, Selex Galileo E-‐mail: [email protected] Registration Date: 16th June 2008 Project Abstract Selex Galileo produce targeting lasers using zig-‐zag geometry diode-‐side-‐pumped Nd:YAG slabs within a crossed-‐Porro prism resonator. The performance of the laser is limited by a time and pump power dependent thermal lens in the laser slab, which can cause both an increase in divergence and a less uniform near field beam profile. If the slab length and the pumped region were altered and if the pumping and cooling were uniform, then it has been shown that the zig-‐zag geometry would cancel out any thermal aberrations. In an attempt to reduce the thermal aberrations in the laser slab, the pump was varied. This has been shown as a successful method for improving laser performance.


Project Title: Next Generation Gas Sensing Technology: Based Upon Mid-‐Infrared Quantum Cascade Lasers Research Engineer: Robert Campbell Sponsor Company: Cascade Technologies Ltd Host University: University of Strathclyde Academic Supervisors: Dr Nigel Langford, Professor Geoffrey Duxbury Industrial Supervisor: Dr Paul Miller E-‐mail: [email protected] , r.campbell@cascade-‐technologies.com, [email protected] Registration Date: 21st September 2009 Project Abstract Laser absorption spectroscopy for gas detection and analysis has many applications. These include pollution control, process optimization, leak detection, atmospheric monitoring, breath diagnostics and homeland security. The mid-‐infrared (ca. 400-‐4000cm-‐1) is known as the ‘molecular fingerprint’ region where many molecules have large absorption coefficients and display narrow and unambiguous vibration-‐rotation absorption lines. In recent years, the Pb-‐Salt diode lasers covering this spectral region have been largely replaced by inter-‐subband pulsed-‐Quantum Cascade Lasers (pulsed-‐QCLs). These offer room temperature operation, higher powers, greater tunability, better beam quality and narrower linewidths. Continuous Wave-‐Quantum Cascade Lasers (cw-‐QCLs) are now available at room temperature. These offer the prospect of higher resolution spectroscopy – via the bandwidth theorem tempered by many instrumental effects -‐ and higher sensitivity spectroscopy -‐ via the easier application of sensitivity-‐enhancing techniques. One relatively straightforward sensitivity-‐enhancing technique is Wavelength Modulation Spectroscopy (WMS). This can allow absorption features to be seen which would otherwise be buried in noise. Here a slow current ramp applied to the laser injection current (ca. 10Hz) scans the laser frequency across the gas’s absorption profile, while a superimposed higher frequency modulation (ca. 10kHz) allows a lock-‐in amplifier to shift the signal to a region of lower noise and filter out noise at other frequencies. A spectrometer has been built and characterized which is capable of comparing the performance of pulsed and continuous wave QCLs. Initial direct and wavelength modulated spectra have been taken of various gases and the results are encouraging.


Project Title: Advanced Design, Fabrication and Test Technologies for Silica-‐based Micro-‐optics

Research Engineer: Matthew Currie Sponsor Company: PowerPhotonic Host University: Heriot-‐Watt University Supervisors: Howard Baker, Heriot-‐Watt University and Jozef Wendland, PowerPhotonic E-‐mail: [email protected] Registration Date: August 2009

Project Abstract Powerphotonic creates custom designed fused silica micro-‐optics and micro-‐optical structures using raster scanned CO2 laser cutting and smoothing. By applying wavefront sensing techniques to customer laser systems, significant increases in efficiency can be achieved when the resulting micro-‐optics are incorporated into the existing system. Results covering the design, fabrication and test of a new class of comparatively high slope and depth micro-‐optics is presented. Design was completed in both ZEMAX and MATLAB and contrasts are shown between the final optic and a more standard cylindrical optic. Succesful fabrication required altogether new methods, for both cutting and smoothing, to enable the manufacture of a usable product. Finally, unique test processes were required that allowed for examination despite the high surface slope of the optic.


Project Title: Power Scaling of High Brightness Multi-‐kilowatt Coaxial CO2 Lasers Research Engineer: Jochen Deile Sponsor Company: TRUMPF Inc. Host University: Heriot-‐Watt University Academic Supervisor: Prof. D. R. Hall, Heriot-‐Watt University Industrial Supervisor: Dr. F. Villarreal, TRUMPF, Inc. E-‐mail: [email protected] Registration Date: December 2008 Project Abstract In the previous year, different modeling tools for optical resonators were discussed. This year, a model based on the diffraction method is used to investigate different properties of a stable-‐unstable-‐hybrid resonator for a coaxial configuration with the goal to improve general performance of the optical resonator and expand the understanding of the optical resonator in regards to power scaling. Additional features, like thermal lensing, are added to the model and the influence of the resonator mirrors shape on thermal loading of the mirror, far field characteristics, polarization and extraction efficiency are investigated.


Project Title: Reduced focal length imaging for mobile devices Research Engineer: James Downing Sponsor Company: ST Microelectronics Host University: Heriot-‐Watt University Academic Supervisor: Prof. Andrew R. Harvey, Heriot-‐Watt University Industrial Supervisor: Ewan Findlay, ST Microelectronics E-‐mail: [email protected], [email protected] Registration Date: 11/11/08 Project Abstract As mobile handsets become more computationally powerful while continuing to reduce in dimensions, it is now more than ever an environment to be reducing the size of individual components that make up today’s mobile device. The primary consideration with regards to the size of a camera module in such a handset is the height of the module along the optical axis. The design of a system with a reduced height that yields an image with a useable pixel population equivalent to that of a conventional camera is an aim of this project. Significant investigations into geometries that reduce the focal length of a camera system have been undertaken over the last decade and of these, the use of multiple apertures represents a good tradeoff between system field of view, image resolution and overall system height. We explore the problem of parallax when imaging with multiple apertures and its effects on sampling frequency and image error in a final reconstructed image. Following this we present a novel imaging geometry for a system that suppresses these effects and explain methods used for the reconstruction of a single high resolution image from multiple small or low resolution images, including image registration and superresolution techniques.


Project Title: Development and Characterisation of Vapour Phase Sacrificial Etching

Research Engineer: Daniel Drysdale Sponsor Company: memsstar® Host University: Heriot-‐Watt University Academic Supervisor: Changhai Wang, Heriot-‐Watt University Industrial Supervisor: Tony O’Hara, memsstar® E-‐mail: [email protected], [email protected] Registration Date: October 2008 Project Abstract This presentation discusses the continuing developments made in the characterisation of vapour phase sacrificial etching for MEMS fabrication process technologies.

There are two common methods for catalysing the reaction of anhydrous HF vapour and silicon dioxide. The first tools developed for this used alcohol as the process catalyst while more recently, a shift has been seen whereby some are looking at the use of water as the process catalyst. While both are acceptable methods, there has never been a direct comparison of the two catalysts on a single hardware configuration which is the focus of the most recent work in this research.

The comparison of etch rates and selectivities for thin films of silicon dioxide and silicon nitride with respect to water and alcohol based (ethanol in this case) catalysts in a vapour phase HF etching process is discussed. Observation of etch rates for both PECVD Oxide and Nitride films are used to describe the behaviour of silicon dioxide etching. These behaviour characteristics can also be used to develop selectivity behaviours between the two films based on each of the catalysts. A number of factors are considered in the vapour phase etching process: the total gas flow for the etching process, process temperature and the etching pressure. The paper discusses the differences between both water and ethanol as process catalysts for the improvement of silicon dioxide etching selectivity with respect to silicon nitride. Results show that using water as a catalyst, a selectivity of up to 40:1 can be achieved while with a direct comparison of the same etch process with ethanol, the highest achievable selectivity is 15:1. On the other hand, with comparable etch rates to that of the water catalyst process, the highest selectivity achieved was 10:1.

EngD Conference Presentation Abstract 2011

Project Title: Quantum optics experiments with single-‐photon sources and detectors Research Engineer: Sponsor Company: Host University: Academic Supervisor: Industrial Supervisor: E-‐mail: Registration Date:

Cat Fitzpatrick National Physical Laboratory Heriot-‐Watt University Dr. Robert Hadfield, Heriot-‐Watt University Dr. Alastair Sinclair, National Physical Laboratory [email protected] September 2008

Presentation Abstract Single photons are a key component in applications such as quantum cryptography and linear optical quantum computing. It is therefore important to be able to reliably determine the performance of single-‐photon sources and detectors. The goal of this project is to develop and extend an existing suite of experiments for characterising single-‐photon sources. To this end, a superconducting nanowire single-‐photon detector (SNSPD) system has been constructed, which extends the available range to telecom wavelengths. However, this year has been focused on completing a set of experiments on quantum dot single-‐photon sources that emit at λ = 900 nm. The reliability with which a source exclusively emits single photons can be determined using a Hanbury Brown and Twiss interferometer. This is important to quantum cryptography, where multi-‐photon pulses could be subjected to a ‘photon-‐splitting’ eavesdropping attack. In order to entangle successive photons from a source, they must exhibit a high degree of similarity (or indistinguishability). This can be determined by measuring the transform limit ratio of the photons, and can also be demonstrated by performing the Hong Ou Mandel experiment. This talk will introduce quantum dot single-‐photon sources, explain the main experiments mentioned above and present preliminary results achieved this year.


Project Title: A Systems Investigation of the Laser Directed-‐Energy Battlespace Project Subtitle: A Statistical Analysis of Laser Energy Distribution in the Transient Regime Research Engineer: Brian K Flemming Sponsor Company: SELEX Galileo Host University: Heriot-‐Watt University Academic Supervisor: Prof G J Gibson, Dr W N MacPherson, Heriot-‐Watt University Industrial Supervisor: Dr S J Harding, Dr S K Kudesia, SELEX Galileo E-‐mail: [email protected] Registration Date: 1st December 2008 Project Abstract The transient regime may be defined as the period of operation between laser switch-‐on and the point when the laser energy output attains a steady-‐state distribution over the beam cross-‐section. During this period, the transverse energy distribution is likely to fluctuate continuously due to factors such as thermal gradients. A statistical analysis is being developed to help characterise this period of laser operation. Of interest is the extent to which the beam energy distribution may be explained by a transverse modal structure as the transient regime evolves towards steady state operation. The outcome of this modelling work is expected to provide a means of evaluating transient regime propagation through a turbulent atmosphere.


Project Title: High Power Industrial Solid-‐State Lasers for Precision Processing Research Engineer: Ben Fulford Sponsor Company: Rofin-‐Sinar UK Ltd. Host University: Heriot-‐Watt University Academic Supervisor: Prof. Denis Hall, Heriot-‐Watt University Industrial Supervisor: Dr. Jason Lee, Rofin-‐Sinar UK Ltd. E-‐mail: [email protected] Registration Date: October 2009 Project Abstract Over the last few years, ultrashort pulse lasers have become more widely used in industry for high quality, precision processing of materials due to their increasing average powers and affordability. Before designing a laser for this market, several parameters need to be considered in order to develop a specification. For this market sector, ultrashort refers to the pulse duration with respect to the material being processed. If the laser pulse is short enough such that the thermal diffusion depth is less than the optical penetration depth, the pulse is considered ultrashort. Therefore, the required pulse durations are typically in the range 0.5 – 100 picoseconds due to differing materials properties. Some of the detrimental physical effects associated with ultrashort pulse machining that limit processing speeds will also be discussed. The repetition rate is important as it can be very high (100’s kHz -‐ MHz). Plasma shielding can therefore occur thus reducing the material removal rate. Heat accumulation can also be a problem at high repetition rates and negates the benefits afforded by ultrashort pulse machining. The pulse energy cannot be increased indefinitely either as there is a point where again, heat accumulation becomes significant. The onset of these effects is material dependant and occurs at different points under different conditions.


Project Title: Impact of thermal lensing effects on the resonator parameters of a high power RF excited CO2 laser

Research Engineer: Viktor Granson Sponsor Company: TRUMPF Inc. Host University: Heriot-‐Watt University Academic Supervisor: Prof. D. R. Hall, Heriot-‐Watt University Industrial Supervisor: Dr. F. Villarreal, TRUMPF, Inc. E-‐mail: [email protected] Registration Date: December 2008 Project Abstract A gradient of the refractive index which is perpendicular to the beam direction is formed in a diffusion cooled CO2 laser by a lateral gas temperature profile. The beam deflection due the refractive index gradient is termed as the thermal lensing effect. In the first section the procedure to calculate the thermal lensing effect is presented. The boundary conditions of the particular laser configuration such as the gas mixture, gas pressure and lateral heat load of the radio-‐frequency excited discharge are taken into account to obtain the focal length of the thermal lensing medium as a function of the lateral position in the inter-‐electrode gap. The impact of the thermal lens on the design of the resonator is investigated in the second section. The optical resonator in the stable direction is modeled using the ABCD matrix formalism where the thermal lensing element is represented by an analytical function. The theoretical results are compared with measured data in the concluding part of the presentation.


Project Title: The Exploitation of Fibre-‐Optic Sensor Technology in Aerospace & Defence Research Engineer: Ryan John Sponsor Company: BAE Systems Host University: Heriot-‐Watt Academic Supervisor: Dr William MacPherson, Heriot-‐Watt University Industrial Supervisor: Dr Ian Read, BAE Systems E-‐mail: [email protected] Registration Date: Oct 2009 Project Abstract The aim of the project is to develop fibre-‐optic sensor systems to improve structural health monitoring capabilities in the aerospace and defence markets. The first major area of interest is the detection and characterisation of impacts including location, energy and damage severity. Piezoelectric sensors were used to investigate damage characterisation through sensor signal analysis and also to investigate location techniques such as triangulation via time-‐of-‐flight and neural network implementations. Following this work, a fibre-‐optic system has been developed using an arrayed waveguide grating as a passive demultiplexer for fibre Bragg grating sensors. This system has been calibrated to allow measurement of both the wavelength shift of the grating to sub-‐picometer resolution and also the strain that this represents to sub-‐microstrain resolution. The ability to simultaneously monitor the low frequency strain in a structure while detecting a dynamic impact event has been demonstrated.


Project Title: Holographic Volumetric 3D displays Research Engineer: Javid Khan Sponsor Company: Holoxica Ltd Host University: Heriot Watt University Academic Supervisor: Alan Greenaway, Heriot Watt University Industrial Supervisor: Ian Underwood, Edinburgh University E-‐mail: [email protected] Registration Date: October 2008 Project Abstract The market for 3D displays has been growing rapidly over the past year in areas like cinema, TV and gaming. Current 3D technology is stereoscopic, based on the illusion of presenting a pair of slightly different images to either eye. This has too many limitations, resulting in a poor 3D experience, leading to a demand for displays capable of delivering a true 3D experience. Holographic technology is one approach that could solve many of the problems with existing 3D displays, however, this has proven to be a difficult technical challenge. The technical approach taken in this project is a bottom-‐up one where we start with the simplest holographic display and work our way up towards more complex ones. This involves simplifying and constraining the display to a fixed number of frames. The display system comprises a proprietary holographic screen, a controller and an illumination subsystem. The holographic screen embeds a number of pre-‐configured interference patterns that are sampled and interleaved across its surface. Any of the stored holograms can be reconstructed simply by shining a pattern of light on to the holographic screen, and changing the pattern changes the reconstructed image. This can be done in any sequence or combination to make simple 3D animations. The holographic screen can be manufactured using conventional techniques with some adaptations including classical analogue holography, digital holoprinters and embossing. A proof-‐of-‐concept laboratory demo was reported in 2010, using a transmission-‐mode holoscreen and a laser projector for illumination and image selection. Up to nine images are stored in the holoscreen where the reconstructed images are large and highly visible under ambient lighting conditions. The next generation prototype is based on reflection holograms with the image selection provided by an optical shutter. This project aims to explore the limits of the technology and to make commercially viable displays.


Project Title: Detection of Suspicious Behaviours Research Engineer: Michael Leach Sponsor Company: Roke Manor Research Host University: Heriot Watt University Academic Supervisor: Neil Robertson, Heriot Watt University Industrial Supervisor: Ed Sparks, Roke Manor Research E-‐mail: [email protected]; [email protected] Registration Date: July -‐ 2009 Project Abstract: As a society we have the need to monitor public and private space in order to prevent criminal behaviour and identify security threats. The scale at which surveillance is undertaken and the density of information in video results in a huge amount of data -‐ the real-‐time analysis of which is at times prohibitively expensive. The objective of this research is to develop algorithms enabling an automated and accurate identification of abnormal human behaviour in an unconstrained surveillance scene. Such a system would provide faster feedback of security relevant information and mitigate the burden on security staff with alarm generation in real-‐time. We do not address low level feature extraction but instead address how features are used for accurate behaviour recognition and anomaly detection. To develop a system capable of meeting our objectives we must identify abnormal behaviours (e.g. loitering, fighting, and chasing). To identify these unusual behaviours we will need to explain the majority of observations as common behaviours such as waiting, meeting, and following. In a typical surveillance scene the abnormality of an activity can often be context specific: the distinction between ‘loitering’ and ‘waiting for a bus’ for example. However the interpretation of contextual information is nontrivial. To enable context dependant anomaly detection we automatically learn scene information which enables conditions of normality to be independently learnt for meaningful sub-‐regions of the scene. Using the scene context model we are able to analyse the probability of observing particular behavioural events given the scene region the observation was taken from. We demonstrate that segmenting the scene into meaningful sub-‐regions enables the detection of behaviour anomalies which have a high statistical representation in the scene however are abnormal in the context of the sub-‐region.


Project Title: Mid-‐IR Frequency Conversion Devices Research Engineer: Mhairi Martin Sponsor Company: BAE Systems Host University: Heriot Watt University Academic Supervisor: Duncan Hand & Malcolm Dunn, Heriot Watt & St Andrews University Industrial Supervisor: Malcolm Watson, BAE Systems E-‐mail: [email protected] Registration Date: October 2008 Project Abstract: From October 2010, a series of placements commenced at the University of St Andrews building on the achievements of Stothard et al in developing a smoothly tunable, stable single frequency source based on the intracavity OPO within a VECSEL (Vertical, external cavity surface emitting lasers) for applications in high resolution spectroscopy. In addition to this, and to address a different application niche, an investigation is being carried out into the limits of simultaneous output coupling the pump and signal waves of the intracavity OPO both theoretically and experimentally. To complement the work in St Andrews, time has been spent at the Institute of Photonics (University of Strathclyde), looking more closely at VECSELs (specifically at 2um) and their use as an OPO pump sources.


Project Title: Fluorescence techniques for identifying cataract presence within human and pig eye lenses

Research Engineer: Mark McCallum Sponsor Company: Edinburgh Instruments Ltd. Host University: Heriot-‐Watt University Academic Supervisor: Prof. Andy Harvey, Heriot-‐Watt University Industrial Supervisor: Prof. S.D. Smith E-‐mail: [email protected] Registration Date: April 2010 Project Abstract The near-‐UV / blue fluorescence of human eye lenses were characterised in an attempt to correlate the changes in fluorescence signature with the level of nuclear cataract damage within the lens. The human lenses were sourced from donors of varying age and a study of the steady state and decay kinetics of thesce lenses was conducted. An attempt was made to correlate the changes in fluorescence characteristics to age and common cataract assessment techniques. The transmission and fluorescence of a number of human corneas were also measured in order to assess how these techniques could be applied to a diagnostic instrument.

In addition, a large number of pig eye lenses were studied and an attempt made to photo-‐induce cataract damage within the lenses and measure the fluorescence changes as a direct result of this irradiation.


Project Title: Photonic Sensors for Measuring Prestress Loss in Nuclear Power Plants Research Engineer: Marcus Perry Sponsor Company: EDF Energy Host University: University of Strathclyde Academic Supervisor: Pawel Niewczas, University of Strathclyde Industrial Supervisor: Michael Johnson, EDF Energy E-‐mail: [email protected] Registration Date: Oct 2009 Project Abstract Structural health monitoring of nuclear safety-‐related structures is considered a crucial aspect of ensuring the safe operation of existing nuclear power plants. To improve and maintain structural integrity, the concrete containments surrounding reactors are compressed (prestressed) using steel tendons. This project aims to instrument tendons with optical fiber Bragg grating (FBG) sensors capable of continuously and automatically monitoring levels of prestress loss. This will not only ensure continued safe operation of existing plants, but will also reduce the economic-‐ and safety-‐ related costs associated with performing conventional lift-‐off measurements. Any successfully developed technology could also potentially be applied to the next generation of nuclear power plants. In the last year, a procedure for plating FBGs in nickel has been developed. This will allow us to braze FBGs to a thin “strain plate”, forming a sensor package suitable for attachment to steel tendons. Other practical progress in this project has included the design and manufacture of the strain plate, a brazing rig and a tendon stressing rig for testing and calibration. An extensive literature survey on the effects of radiation on optical fiber sensors has allowed us to modify our sensor package accordingly. We have also made steps towards designing a sensor interrogation system capable of measuring the minute ~10 newton monthly force changes in prestress induced by concrete creep and shrinkage.


Project Title: Micro-‐mechanical sensors for medical diagnostic applications Research Engineer: Lucy A. Williamson Hodge Sponsor Company: STFC Host University: Heriot Watt Academic Supervisor: Prof. A. Kar, Heriot Watt Industrial Supervisor: Prof E Huq, STFC E-‐mail: lucy.williamson-‐[email protected] Registration Date: October 2008 Abstract: There is significant research interest in label free biosensors for medical diagnostics, but as yet relatively little commercial output. Most biosensors transduce surface bound antibody-‐antigen binding reactions into a signal via optical, electrochemical or mechanical means. The associated problems of non-‐specific binding, bio-‐fouling, cost and lifetime of the antibodies, are barriers to the exploitation of the underlying technology. A micro-‐mechanical sensor for medical diagnostics is presented. Measurements are based on physical properties of the fluid analytes, therefore surface functionalisation is not required. In addition, the device boasts integrated electrical sensing for reduced footprint, and disposable components that are suitable for a clinical setting. Preliminary results in monitoring biological processes and identification of disease stages are presented with discussion of possible correlation between the biological system and physical measurement.

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EngD Yearbook - Conference Abstracts 2011 Programme 2010/2011, ENGINEERING DOCTORATECENTRE! PARTNERSHIPBETWEEN HERIOT1WATT,!ST ANDREWS,!STRATHCLYDE,! AND!GLASGOW UNIVERSITIES! CONFERENCEPROGRAM