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Title: Combinations of techniques for the advancement of scanning laser ophthalmology and optical coherence tomography
Author: Meadway , Alexander
Awarding Body: University of Kent
Current Institution: University of Kent
Date of Award: 2013
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In this thesis methods of eye imaging are investigated, primarily optical coherence tomography (OCT) and scanning laser ophthalmology (SLO). These are two well established technologies. This thesis investigates the combination of techniques to improve resolution, sensitivity and the amount of information that can be extracted from a device. There are three systems presented in the thesis. The first generates on-axis and off axis confocal retinal images simultaneously by way of a drilled mirror. Off-axis imaging provides greater depth penetration, but at the cost of resolution. The second system combines three technologies; SLO, time domain (TD) OCT and adaptive optics (AO). The system is able to generate simultaneous en-face SLO and OCT images, whilst the AO closed loop corrects for aberrations enhancing the intensity and resolution of the images in both modes. This system is used in several investigative directions; the effect of deformable mirror dynamics on the acquired image; the OCT channel is used to investigate the confocal profile; the performance of the deformable mirror with regards to its focus control is investigated; the focus control is used to generate 3D confocal images. Finally, the system is converted to a balanced Fourier domain (FD) OCT system. It has previously been assumed that excess photon noise (that balanced detection is used to remove) is not significant due to the limitations of the CCD camera used in an FD system's spectrometers, however, CCD cameras have since been developed, with increased depths of quantum wells and balanced detection offers other advantages, such as the removal of auto correlation terms from an image. The third system investigated is a TD-OCT system that spectrally separates the broadband source into discrete channels at detection. It can be viewed as a hybrid system, combining TD and FD OCT. A system such as this may be used to reduce the shot noise of a time domain system, or it may be used to make spectroscopic measurements. Both are investigated in this thesis, dispersion was measured as well as absorption profiles and a preliminary investigation into the noise reduction is also presented.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available