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A proof of concept virtual reality system is presented that integrates ultrasonic feedback sensations to provide a demonstrative virtual reality exposure therapy environment containing multiple scenarios with virtual spiders. This system and environment were utilised to conduct a study containing 35 participants with the goal of investigating the effect the environment could have on their level of anxiety. This level of anxiety was measured in three different forms: changes in frontal asymmetry analysis of EEG data, changes in skin conductance levels and subjective units of distress. The Fear of Spiders Questionnaire was used to determine which participants in the study reported to be moderately afraid of spiders. For these participants all three measurement forms for anxiety showed statistically significant increases in a comparison between baseline and scenarios with the virtual spiders. A statistically significant correlation between scores on the Fear of Spiders Questionnaire and changes in anxiety shows the system to have had a greater effect on the anxiety levels of those who were more afraid of spiders, than those who were not. There was also a statistically significant correlation discovered between immersion and increase in anxiety, highlighting the significance of immersion in future virtual reality exposure therapy applications.

Optical fibres have played an important role in the advancement of real-time dosimetry in clinical applications in recent years. Significant work has been done to increase precision and accuracy in detecting radiation doses during treatment, to avoid the negative effect that can ensue from irradiating healthy tissue around the tumour. The drive to develop distributed measurement in optical fibres has been limited to the slow scanning speed systems from optical time domain reflectometry (OTDR), however for radiotherapy dosimetry, with often short radiation pulse durations, fibre Bragg grating (FBG) interrogation is a better alternative because of the fast-scanning speed. The work presented here includes the preliminary results in the characterisation of CYTOP FBGs on exposure to X-ray radiation emitted from a clinical linear accelerator (linac) machine. A blue shifted linear response of the Bragg wavelength with sensitivity of 6.655 pm/Gy, 6.519 pm/Gy and 7.153 pm/Gy at the three main peaks (1522 nm, 1542 and 1561 nm), was recorded for a 9 Gy of radiation at a dose rate of 1.758 Gy /min with an amplitude fluctuation within the duration of radiation. The response demonstrates the potential for its use in low dose radiation dosimetry, providing for quasi-distributed sensing in radiotherapy.

The following presents a comparison of an extrinsic Fabry–Perot interferometer (EFPI)-based temperature sensor, constructed using a novel diaphragm manufacturing technique, with a reference all-glass EFPI temperature sensor. The novel diaphragm was manufactured using polyvinyl alcohol (PVA). The novel sensor fabrication involved fusing a single-mode fibre (SMF) to a length of fused quartz capillary, which has an inner diameter of 132 μm and a 220 μm outer diameter. The capillary was subsequently polished until the distal face of the capillary extended approximately 60 μm beyond that of the single mode fibre. Upon completion of polishing, the assembly is immersed in a solution of PVA. Controlled extraction resulted in creation of a thin diaphragm while simultaneously applying a protective coating to the fusion point of the SMF and capillary. The EFPI sensor is subsequently sealed in a second fluid-filled capillary, thereby creating a novel temperature sensor structure. Both temperature sensors were placed in a thermogravimetric analyser and heated from an indicated 30 °C to 100 °C to qualitatively compare sensitivities. Initial results indicated that the novel manufacturing technique both expedited production and produces a more sensitive sensor when compared to an all-glass construction.

While ever higher resolution temperature sensing is of demand in research and industry, the cost of sensors in the sub-milli-Kelvin (mK) range can be restrictive. Furthermore, as the majority of commercial temperature sensor measurements are transmitted via electrical circuits, significant post-processing is required to obtain a high-resolution due to phenomena such as electromagnetic interference, selfheating, electrical noise, etc. Consequentially, research in recent years has focused on the development of several technologies which overcome this issue, with optical fibre sensors proving to be a viable option. Owing to this, the following chapter will aim to review the current state-of-the-art in liquid filled optical fibre temperature sensing and the underlying methods.