| Optical coherence tomography(OCT) is a rapidly developing biomedical imaging technique which allows for noninvasive, noncontact, cross-sectional imaging of weakly scattering biological tissue in real time with high sensitivity. It has been widely applied in clinical for diagnosis of retinal diseases.Swept-Source OCT is one kind of Fourier-Domain OCT, which avoids mechanical axial scan in the reference arm and acquires the depth information of samples by Fourier transform spectrum signal. Thus it offers significant advantages in imaging speed, signal noise radio and detection sensitivity. In this study, we built a SS-OCT system, with seven modules, such as swept laser source, reference arm, sample arm, balance detector, sample scanning, data acquisition, data processing and visualization. We set up and build each module above respectively. A set of imaging software based on LabVIEW for SS-OCT system is developed, which can image many different kinds of samples in real-time. In our system the axial resolution is 7.4 um, the imaging depth is 3.7 mm in air.OCT is based on low coherence interferometer and consequently suffers from speckle noise inherently, which can degrade image quality and obscure micro-structures. In this study, we proposed a depth-encoded angular compounding method to reduce speckle noise of OCT image. Two different angular light paths are created on the sample arm using two beam splitters and a pair of mirrors. The epi-detection scheme creates three different combinations of the two angular light paths above, which produce three images in single B-scan. Speckle noise can be reduced by average three images. Compared to those reported angular compounding methods, our method showed an advantage of faster imaging speed. This method was evaluated on an artificial eye model. The results demonstrated a 1.46-fold improvement in speckle contrast. |
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