EngD Optics and Photonics Technologies Conference
Tuesday, 11th August 2009, Postgraduate Centre, Heriot-Watt University
Programme of Abstracts
Mike Poulter (Powerlase)
High Average and peak power solid-state lasers for industrial applications
The direct side-pumping of Nd:YAG rods with laser diodes has been shown to be a cost effective scheme for
scaling to simultaneous high average and high peak power operation. Careful control of the parameters that
govern the performance of a multi-spatial mode MOPA system has led to the demonstration of reliable
Q-switched average powers of up to 1600 W and peak powers in excess of 18 MW at the 1064 nm
fundamental wavelength. The techniques used to refine the properties of an infrared stable resonator in order
to optimise intra-cavity second harmonic generation are discussed. Average powers of up to 290 W and peak
powers of up to 0.45 MW at 532 nm have been demonstrated from a single cavity. By polarisation multiplexing
the outputs of two cavities emitting at 532 nm, we have achieved single-beam average and peak powers of up
to 580 W and 0.9 MW respectively and gained flexible control of pulse duration and temporal shape.
Thomas Legg (SIFAM)
High Power Fibre Laser Component and System Development
This presentation reports on the development of a long-range methane sensor based on a combination of fibre
amplifiers and near-IR tuneable diode laser spectroscopy. It also covers the development of a fibre-in beam-out
isolator focussed specifically on understanding and controlling thermal lensing; and the results of some
preliminary research into the construction of an actively q-switched fibre laser using a fibre coupled acoustooptic modulator.
Veronika Tsatourian (NPL)
Characterisation of a novel self-referencing scheme for a Ti: sapphire based femtosecond
comb
A new improved set-up for control of the carrier-envelope offset frequency (f0) in a Ti : sapphire femtosecond
laser based frequency comb has been demonstrated. Commercially-available microstructure fibre spliced to
single mode fibre is used for spectral broadening. A periodically poled KTiOPO4 crystal is used for second
harmonic generation with zero walk-off angle, which enables collinear propagation of beating beams in the selfreferencing set-up. An increase of signal-to-noise ratio by 10 dB has been achieved. Improvements in offset
frequency stability and continuous frequency measurement capability were demonstrated.
James Beedell (Selex Airborne Systems)
Multifunction Lasers
Stephan Kloss (Renishaw)
Integration Of Laser Into A Parallel Kinematic Machine For Material Processing
The overall objective of this project is to integrate fibre delivered laser light with a novel, multi-axis motion
system for application to a number of manufacturing processes. This would provide a potential low cost solution
for delivery of laser light to a 3D workpiece in comparison with existing, expensive robotic arms used for laser
welding and cutting technologies, and allow new 3D applications to be addressed.
Yves Lacrotte (Renishaw)
Micro-Patterning of Green Tape Ceramic Using Powder Blasting for LTCC Manufacturing
Gez Wong (Selex Gallileo)
Snapshot Hyperspectral Imaging with IRIS
James Bain (Rolls-Royce)
Near-Infrared Tunable Diode Laser Spectroscopy for Aeroengine Related Applications
The development of rugged and low-cost distributed feedback laser diodes has led to a rapid expansion in the
use of near-infrared absorption spectroscopy as a method of measuring gas parameters in industrial systems.
This project aims to extend novel and established methods for tunable diode laser spectroscopy (TDLS) for the
purposes of monitoring aeroengines during ground testing.
A great deal of information about aeroengine processes can be gained from monitoring the atmospheric gases
and combustion products. The absorption line-shape features that yield useful information include:
concentration from peak depth, pressure from line-width, velocity from Doppler-shift and temperature from the
linestrength ratio of multiple lines.
Initial experiments will monitor engine intake air temperature using ratio thermometry of atmospheric water
vapour lines. A laboratory prototype has been constructed in an environmental chamber to test the sensitivity of
water vapour absorption lines near 1350nm to changes in ambient temperature and further testing has been
carried out on a Rolls-Royce Viper engine. Subsequent investigations could monitor intake air mass flux,
indirect core mass flow and exhaust plume composition and temperature.
Gordon McKenzie (BCF Designs Limited)
Non-Invasive Voltage Measurement by Capacitive Coupling
Voltages on cables can readily be measured via a capacitive interface at high frequency, but at low frequency
and at DC, it is much more problematic. Vibrating variable capacitors can be used to perform this function, but
the moving parts they entail are not always desirable. This project seeks to realise the goal of non-contact
measurement of DC voltages by means of an electronic equivalent of a vibrating capacitor. The main
application is in cables and wiring, but it can also be applied elsewhere.
Suzanne Millar (MCS Limited)
Ultra Low Leak Detection Methods for MEMS Packaging
Many MEMS devices require hermetic packaging for reliable operation. This study aims to show the limitations
of currently used hermeticity test methods when applied to small cavity volumes and glass or polymer
packaged devices. The main objective of this study is to find new ways of assessing leak rates for extremely
small cavities, such as those encountered in MEMS. One method involves using Fourier Transform Infra-Red
spectrometry, FTIR, to probe packages containing an appropriate tracer gas. By comparing FTIR absorption
peaks over time, a leak rate for the package can be determined. Raman spectroscopy can be used without the
need for a tracer gas for failure analysis applications. Test structures are also being developed to allow
hermeticity of MEMS devices to be monitored electrically at any stage of the device lifetime.
Andrew White (Selex Galileo)
Developments in High Peak Power Solid State Lasers
Alan Proudfoot (BAE Systems)
WDM Commercial Fibre-Optic Technology for Aerospace and Defence Platform Applications
Fibre optic technology is already well established, with the first generation systems already deployed on the
Airbus A380 and Eurofighter Typhoon aircraft. The increased usage of composites in aircraft such as the JSF,
UAV’s and the A350, the larger number of sensor systems, higher bandwidth requirements and more complex
networks will drive this technology further in future aircraft. Affordable fibre optic hardware, higher bandwidths
and the addition of different applications onto multiplexed networks will be key issues for the next generation of
avionic networks.
IN this presentation, we will look at experimental work done in the third year of this project, then an optically
amplified CWDM link, using a Semiconductor Optical Amplifier (SOA). The results allow the optimum
positioning of the amplifier within the network to be identified by analysing the system losses.