Spectral domain optical coherence tomography using multi-line single camera spectrometer

Abstract

Optical coherence tomography (OCT) was demonstrated as a promising imaging embodiment that enables high-resolution, cross-sectional noninvasive tomographic image. This technique is analogous to ultrasound imaging, except that it measures the reflected intensity of near-infrared (NIR) light, rather than sound waves. In optical coherence tomography based on the principle of the Michelson interferometer, the backscattered or back-reflected lights from different depths of the specimen are interfered with known delay light from the reference mirror. And functional imaging techniques in optical coherence tomography are based on the characteristics of the light such as polarization, Doppler Effect and absorption, which can give crucial information in some applications including the pathology and material analysis. Spectral domain optical coherence tomography (SD-OCT) is usually composed of broadband light source, sample arm, reference arm and spectrometer for detection. It can achieve cross-sectional image of the internal micro-structures by Fourier-transforming the spectral interference pattern measured by the spectrometer. The polarization-sensitive spectral domain optical coherence tomography (PS SD-OCT) usually needs two detection channels in the spectrometer to detect two orthogonally polarized interference beams. This two-camera system has a high cost, a complex configuration, alignment errors and difficulties in synchronized triggering of two-camera spectrometer. Thus, the detection schemes based on single camera spectrometer have researched a lot. In this thesis, polarization-sensitive spectral domain optical coherence tomography using multi-line single camera spectrometer is proposed. The novel spectrometer was based on the customized multiplexed grating and a three-line single camera. The incidence angles of two collimators are horizontally about an angle of $\plusmm 60$ degrees with regard to the multiplexed custom grating. After two polarized interfer...