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  Tamer Y. Cosgun
Project Title: Fibre Sensors for Inaccessible Locations
3rd Year
AWE/Heriot-Watt University
Supervisors: William N. MacPherson and Matthew Kingston
The Project
Structural health monitoring identifies damage or structural degradation and informs remediation decisions. Using Fabry- Perot interferometry, the long-term variation of the distance between component parts is measured and can be used to inform decisions regarding to the structure’s overall condition. Care is needed to ensure that the sensor installation does not compromise the existing structure and small-scale sensors, such as optical fibre sensors, are one means to achieve this. The challenges associated with embedding in certain geometries is addressed
by incorporating micromachined turning mirrors on the fibre end face - light exits perpendicular to the fibre axis and therefore is capable of being positioned into confined regions otherwise inaccessible for monitoring.
Two fabrication methods are investigated: Focused ion beam (FIB) milling, and ultrafast laser
assisted etching (ULAE) of the cleaved fibre end. FIB milling consists of removing material via
a gallium ion beam, and ULAE consists of ultrafast last inscription to modify the substrate material which is then chemically etched and removed. These approaches have resulted in sensor repeatabilities
of + or -5 nm and accuracies
of + or - 40 nm, over a range of approximately 10 mm and 6 mm, respectively. The benefit of the FIB milling process is superior sensor range, however ULAE carries more potential for batch production.
These nanometre resolution Fabry-Perot fibre sensors could
be effective tools for structural health monitoring applications, whether it be to measure fatigue or the effects of outgassing. Beyond its primary objective of structural health monitoring, there may also be applications in imaging and component alignment regarding laser fabrication processes or photolithography.
The CDT Programme
The programme has been challenging yet rewarding. Coming from a mechanical engineering background, it has allowed me to see my skillset expand beyond what I thought myself capable of and has enabled versatility to be one of my strongest traits when it comes to problem solving challenges.
The programme has been challenging yet rewarding
The support I have received from both the CDTAP and my cohort have been a highlight throughout the duration of the programme, and I look forward to seeing how it can continue to improve in the future.
Liam Henwood-Moroney
Project Title: Novel components for biomedical imaging
3rd Year
Gooch & Housego/University of Strathclyde
Supervisor: Gordon Flockhart
The Project
Novel fabrication methods and design of optical components to enhance certain properties, such was wavelength dependence, these then enable higher/improved resolutions in low-coherence interferometry and therefore optical coherence tomography, which is used in medical diagnosis.
The project has had good results on a component level, +50% improvement on the market offerings. Also, very good result on system level, very high resolution imaging obtained of the retina of a human volunteer.
The impact of the research enables specialist equipment for improved diagnosis of eye diseases such as glaucoma.
The CDT Programme
My overall experience of the programme is of great support from the staff and good opportunities
to gain experience in all aspects of engineering.
24 | Centre for Doctoral Training in Applied Photonics

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