Abstract

Optical Coherence Tomography (OCT) is a high-resolution non-invasive and non-contact imaging technology. Traditionally, multi-axis spot-focused scanning is used for transverse scanning to obtain a two or three-dimensional OCT image. This increases the time to acquire an image and imaging performance is affected by motion artifacts. Moreover, lenses are used in the state-of-the-art OCT systems that reduce the axial resolution due to chromatic aberration, and affect the imaging quality due to distorted scan field.
In order to avoid the problems mentioned above, the objective of the present thesis is to develop a reflective optics-based line-scan spectral domain OCT system for high-quality three-dimensional imaging. Cylindrical mirror used in this thesis for focusing eliminates chromatic aberration and provides a flat scan field. Line scanning reduces the requirement of scanning to one axis and thereby making the image acquisition faster. A novel reflective optics based line-scanning system with a spectrometer has been designed, and also the scanning system has been verified experimentally.
The design of the scanner includes analytical and optical modeling of the proposed scanning configuration, along with the development of experimental setup and validation. Scanning system parameters that affect the imaging quality were studied and selected in the design. In addition, optical modeling of a reflective optics spectrometer was carried out, and an analytical model was developed for spectral domain OCT signal processing. Marechal criterion of Strehl Ratio above 0.8 was used as a benchmark to evaluate the imaging quality of the proposed system.
To validate the line scanning model, an experimental setup consisting of a 53nm spectral bandwidth light source with cylindrical mirrors of 25.85mm and 51.7mm focal lengths was developed. Scanning was performed in both tangential and sagittal directions. The improvement in imaging performance by using sagittal scanning was demonstrated. It was also proved experimentally that the mirror focusing is insensitive variations in beam positions.