Abstract:
SD-OCT is an imaging technique that provides cross-sectional images with micrometer resolution up to a depth of a few millimeters. Image acquisition is fast as backscattered information is acquired from multiple depths encoded in a single acquisition. As a result, SD-OCT can be combined with phase resolved OCT for functional analysis. In particular, the spectral domain technique uses the principle of Doppler shift to measure velocity of moving targets. In this research, an existing SD-OCT system at The University of Auckland is developed into a Doppler OCT system through the implementations of new data processing algorithms. The principle of Doppler shift was used to acquire velocity measurement of milk ow through a 680 µm glass capillary. Velocity measurements were acquired at a range of ow rates and Doppler angle values. Based on experimental measures and the concepts of phase stability and speckle correlation, velocity between the range of 8 µm/s and 1:03 mm=s was quanti ed. Although velocity higher than 1:03 mm=s could not be quanti ed a measure of ow distribution at 3 mm=s using the technique of Doppler variance was obtained. Apart from velocity analysis, Doppler OCT was also used to determine Poisson's ratio for aluminium and copper. This was achieved by vibrating the samples at excitation frequencies of 120 Hz and 40 Hz. The ratio deviated from the theoretical at higher and lower excitation frequencies. It was concluded that the shaking system was not stable and a better design was proposed. Finally, the thesis proposes the application of the Doppler principle to SSOCT for ow analysis in micro uidic devices.
