Depth-encoded all-fiber swept source polarization sensitive OCT

Abstract

Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of conventional OCT and can assess depth-resolved tissue birefringence in addition to intensity. Most existing PS-OCT systems are relatively complex and their clinical translation remains difficult. We present a simple and robust all-fiber PS-OCT system based on swept source technology and polarization depth-encoding. Polarization multiplexing was achieved using a polarization maintaining fiber. Polarization sensitive signals were detected using fiber based polarization beam splitters and polarization controllers were used to remove the polarization ambiguity. A simplified post-processing algorithm was proposed for speckle noise reduction relaxing the demand for phase stability. We demonstrated systems design for both ophthalmic and catheter-based PS-OCT. For ophthalmic imaging, we used an optical clock frequency doubling method to extend the imaging range of a commercially available short cavity light source to improve polarization depth-encoding. For catheter based imaging, we demonstrated 200 kHz PS-OCT imaging using a MEMS-tunable vertical cavity surface emitting laser (VCSEL) and a high speed micromotor imaging catheter. The system was demonstrated in human retina, finger and lip imaging, as well as ex vivo swine esophagus and cardiovascular imaging. The all-fiber PS-OCT is easier to implement and maintain compared to previous PS-OCT systems and can be more easily translated to clinical applications due to its robust design. Aretz, E. F. Halpern, and B. E. Bouma, "In vivo characterization of coronary atherosclerotic plaque by use of optical coherence tomography," Circulation 111(12), 1551-1555 (2005).

Estimation of Jones matrix, birefringence and entropy using Cloude-Pottier decomposition in polarization-sensitive optical coherence tomography

“…Among them, Makita et al raised one of the fundamental issues in PS-OCT that the mean of the phase retardation is significantly biased from the true value because of asymmetric distribution [10]. Various methods have been developed to apply averaging to such polarimetric parameters [11][12][13][14][15][16][17][18][19]. In another approach, an estimator of the phase retardation based on the likelihood of the distribution was also developed [20].…”

Three-dimensional multi-contrast imaging of in vivo human skin by Jones matrix optical coherence tomography

“…The limitation of cumulative phase retardation imaging can be overcome by the birefringence measurement based on localized Jones matrix measurement [23][24][25]. Although the local Jones matrix measurement suffers from a low signalto-noise ratio and inaccurate phase-retardation and birefringence, these problems were recently resolved by birefringence and phase retardation estimation techniques that include the coherent averaging of the Jones matrix and/or Jones vector [26][27][28], eigen-value-based averaging [29], Jones matrix estimation based on the Cloude-Pottier decomposition [30], Muller analysis [31,32], a specially designed phase-retardation estimation function [33], and maximum a posteriori birefringence estimators [25,34,35]. These advances enabled the birefringence imaging of in vivo skin.…”

Fiber-based polarization-sensitive OCT for birefringence imaging of the anterior eye segment

“…In order to measure these parameters without reducing the effective A-scan rate in SS-OCT, frequencyor depth-multiplexing methods have been developed [17,[29][30][31][32]. Wang et al [33] applied electric frequency doubling of the sampling clock to extend the axial measurement range of the depth-encoded PS-OCT. Although the electric frequency doubling is effective, its applicability is limited by the bandwidth of the frequency multiplier.…”