DEVELOPMENT OF PHASE STABILIZED SWEPT SOURCE OPTICAL COHERENCE TOMOGRAPHY FOR BIOMEDICAL IMAGING AND SENSING
Several life-threatening diseases could either be cured or be eased by diagnosing them during earlier stages. Currently, medical imaging is one of the most reliable methods of disease diagnostics. This dissertation describes the development of a medical imaging device that has a great potential for early diagnosis of various diseases. The developed system utilizes optical coherence tomography (OCT) and is capable of 3D imaging of tissues with near cellular resolution noninvasively. It is also capable of sensing minute changes in tissue refractive index or surface displacement via phase-sensitive measurements. The system showed an axial resolution of 8 µm, lateral resolution of 15 μm, an imaging depth of 9 mm, signal to noise ratio of 101 dB and a phase stability of 9 mrad.
After development, the system was applied to several biomedical applications such as the detection of microbubbles in mice tails in vivo and mechanical wave propagation in mice corneas in vivo. In the live mice tails, microbubbles of sizes as small as 50 μm were detected, therefore indicating the capability of the system to serve as an early diagnostic tool for diseases caused by decompression sickness or gas emboli. Apart from imaging, this dissertation also describes a method to apply OCT for elastography applications. Results demonstrate that the system is capable of measuring amplitude of mechanical waves as small as 30 nm. The high sensitivity of the system was exploited to measure wave propagation in live mice corneas as a function of age. To the best of our knowledge, this is the first time OCT has been applied to measure wave parameters in ocular tissues in vivo.