Analog differential-phase detection in optical coherence reflectometer.

A novel differential-phase optical coherence reflectometer (DP-OCR) was proposed using a low-coherence source, integrating it with an analog differential-phase decoding method. In the experiment, the DP-OCR performed a localized surface profile measurement of an optical grating (1200 lp/mm) and demonstrated its ability to measure the translation speed of a tilted mirror. Experimentally, the resolution of the axial displacement of proposed DP-OCR at 185 pm was demonstrated.

Polarization-sensitive optical coherence tomography for imaging human atherosclerosis.

Polarization-sensitive optical coherence tomography (PS-OCT) combines the advantages of OCT with image contrast enhancement, which is based on its ability to detect phase retardation and the fast-axis angle. Both PS-OCT images and histopathology have demonstrated similar features that allowed differentiation of atherosclerotic structures (i.e., plaques) from normal tissue. Moreover, the picrosirius polarization method was used to confirm PS-OCT assessment of collagen in the fibrous cap of atherosclerotic plaques, and high-frequency (40 MHz) ultrasound images were used to identify calcium in the vessel wall. Our preliminary ex vivo investigation of human aortic specimens indicated that PS-OCT might help to identify atherosclerotic lesions.

Development of Linearly Polarized Optical Coherence Tomography and the measurement on Porcine Tendon Birefringence.

A novel polarization-sensitive optical coherence tomography (PS-OCT) using only linearly polarized light is proposed. To compare with conventional PS-OCT which use circular polarized incident light, linear PS-OCT shows three advantages: (1) in a turbid medium with linear birefringence, the degree of polarization of backscattered light for linearly incident light dose not change significantly; (2) Phase retardation (PR) of the sample can be obtained totally from the phase-difference between the polarization heterodyne signals, thus common phase noise rejection mode is introduced inherently. These advantages lead to the immunity of background phase noise and laser frequency noise simultaneously, and also lead to the better sensitivity of PR measurements; (3) the dynamic range of PR in this system is between 0° to 180°, which is two times larger than that of conventional circular PS-OCT.