Development of Functional Optical Coherence Tomography

Optical coherence tomography (OCT) has the advantages of non-invasive, depth-resolved and high-speed imaging without the destruction of samples. OCT can reconstruct the two-dimensional or three-dimensional microstructures with the resolution in micrometer scale, enabling the measurable imaging depth to achieve 3 mm below the sample surface. In this proposal, we will develop a frequency-sweeping laser source for OCT systems, and functional imaging techniques including measurement of blood velocity, reconstruction of vascular pattern and evaluation of birefringence of biological tissues. Limited to the decrease of scattered intensities when the wavelength increases, a swept source in near-infrared spectral range will be demonstrated to probe the deeper structures of human skin. Furthermore, unconscious motions from samples will induce motion artifacts in OCT images. Thus, the improvement in OCT imaging speed can effectively remove motion artifacts, and the imaging speed of OCT system is determined by the scanning rate of swept source. Therefore, in the first year of the proposal, we propose a novel structure to effectively improve the scanning speed of light source, which is three times than that of best commercial light source. Moreover, with a broadband design, the light source can provide an OCT axial resolution of 5 µm and a scanning rate of 280 kHz. It also can provide two-channel output and the output powers from each output end can be more than 50 mW. In the second year, we propose a novel OCT configuration, two-reference-arm interferometer, with the swept source developed in the first year. With the two-reference configuration, the phase noise from dispersion and polarization fluctuation due to fiber can be eliminated, effectively increase the measurable range of blood velocity. In the third year, the swept source is also implemented for the development of polarization-sensitive OCT system. Every adjacent A-scans will be set to be the horizontal and vertical polarization states, respectively. Then, the polarization information from the sample can be detected by the balanced detectors, sequentially. Such structure can eliminate the phase noise due to the changes in polarization states without scarifying the imaging speed of OCT system.

Project ID:PB10308-3325
External Project ID:MOST103-2221-E182-039