Refractive-index mismatch in conventional confocal microscopy produces severe degradation on axial resolution of
sectioning image because the spherical aberration is generated in specimen. In this study, we propose a polarized
photon-pairs confocal laser scanning microscope (PCLSM) in which a two-frequency linear polarized photon-pairs
(LPPPs) laser beam is produced. The common-path propagation of LPPPs integrated with optical heterodyne technique
not only can reduce the spherical aberration but also decreases scattering effect in specimen at same time. Therefore, the
better axial and lateral resolutions of the sectioning image are produced simultaneously. In the experiment, a verification
and comparison between PCLSM and conventional confocal laser scanning microscope (CLSM) on the ability of
cancellation of spherical aberration induced by cover glass are demonstrated experimentally. Finally, the ability of
PCLSM which can decrease the spherical aberration based on the common-path propagation of LPPPs associated with
polarization gating, spatial coherence gating and spatial filtering gating is discussed.
We developed a novel differential-phase optical coherence reflectometer (DP-OCR) by using a low-coherence light
source and integrated with differential phase detection technique on surface profile measurement. In this setup, 2Å on
detection of axial displacement was demonstrated. Thus, a localized surface profile was measured precisely by
scanning an optical grating surface in this measurement. Moreover, the requirement on equal amplitude of the reference
and signal beams of this novel reflectometer is discussed.
Atherosclerosis is unquestionably the leading cause of morbidity and mortality in developed countries. In the mean time, the worldwide importance of acute vascular syndromes is increasing. Because collagen fiber is a critical component of atherosclerotic lesions; it constitutes up to 60% of the total atherosclerotic plaque protein. The uncontrolled collagen accumulation leads to arterial stenosis, whereas excessive collagen breakdown weakens plaques thereby making them prone to rupture finally. Thus, in this study, we present the first application, to our knowledge, of using polarization-sensitive optical coherence tomography (PS-OCT) in human atherosclerosis. We demonstrate this technique for imaging of intensity, birefringence, and fast-axis orientation simultaneously in atherosclerotic plaques. This in vitro study suggests that the birefringence change in plaque is due to the prominent deposition of collagen according to the correlation of PS-OCT images with histological counterpart. Moreover, we can acquire quantitative criteria based on the change of polarization of incident beam to estimate whether the collagen synthesized is "too much" or "not enough". Thus by combining of high resolution intensity imaging and birefringence detection makes PS-OCT could be a potentially powerful tool for early assessment of atherosclerosis appearance and the prediction of plaque rupture in clinic.