新潟大学Niigata University博士（工学）Optical coherence tomography (OCT) is a non-invasive, non-contact optical imaging modality for assessing internal microstructure of samples. Over three decades, OCT, has combined with a variety of other approaches to continuously stimulated research and development within this field. Especially, the swept source OCT (SS-OCT) employing a swept source has attracted great attention due to its large imaging depth and high imaging speed. Since the characteristics of swept sources affect performances of OCT systems, it is necessary to develop an advanced swept source, including broad spectral bandwidth, narrow instantaneous linewidth, and high scanning speed, etc. The linear-wavenumber swept source is a specifically important characteristic because it ensures that the optical interference fringe is in linearized wavenumber space before the fast Fourier transformation in an SS-OCT system. However, most swept sources follow a linearized wavelength scale. When using such a wavelength-swept source, an additional procedure of resampling and interpolating the optical interference fringe evenly in wavenumber space becomes necessary; otherwise, reconstruction errors and resolution degradation is inevitable in OCT imaging. To address this problem, this thesis developed a linear-wavenumber swept source for the OCT system. The linear-wavenumber swept source shows strong linearity in the 1.3 μm region, justified by a high goodness of fit R2 value of 0.9998. Additionally, its scanning range, output power, and linewidth are 120 nm, more than 43 mW, and approximately 0.6 nm, respectively. The sweep rate is 350 Hz after the linear wavenumber compensation of the experimental equipment. We proved the effectiveness of the linear-wavenumber swept source by applying it to measure a sample distribution without wavenumber-domain resampling before the Fourier transform. This successful implementation indicates that the linear-wavenumber swept source has practical potential for application in SS-OCT systems.新大院博(工)第553号doctoral thesi
