Time-of-flight measurements of single-layer tissue with a chip-based optical frequency comb
N. Li (TU Delft - Mechanical Engineering)
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Abstract
Cerebral oxygen saturation is an important indicator that reflects the oxygen metabolism of the brain tissues in such patients. The utilization of near-infrared spectroscopy (NIRS) enables the identification of the oxygen saturation levels in nearby tissues by analyzing the distinct oxygenation states of hemoglobin-oxyhemoglobin (HbO2) and the distinctive molecular spectrum of deoxygenated hemoglobin (Hb). It is helpful to realize the objective of noninvasive continuous detection on cerebral oxygen saturation because near-infrared radiation can directly penetrate the skull to obtain the characteristics of the average oxygen saturation of the brain tissues. This also allows a noninvasive way to monitor blood flow in the brain. A frequency comb is a pulsed laser in the time domain and a sequence of discrete, uniformly spaced frequency lines in the frequency domain. Applying the frequency comb to NIRS has the potential to develop a high-speed and fs-level time-of-flight resolution blood flow measurement system. The objective of this thesis is to utilize a chip-based optical frequency comb as an illuminating source in order to conduct time-of-flight measurements of a single target, employing a Michelson interference experiment. The establishment of the time of flight in the single-layer case and the investigation of the non-ambiguity range form the fundamental basis for future experiments multi-layer.