Imaging myocardial fiber orientation using polarization sensitive optical coherence tomography.

Knowledge of myocardial fiber architecture is essential towards understanding heart functions. We demonstrated in this study a method to map cardiac muscle structure using the local optical axis obtained from polarization-sensitive optical coherence tomography (PSOCT). An algorithm was developed to extract the true local depth-resolved optical axis, retardance, and diattenuation from conventional round-trip results obtained in a Jones matrix-based PSOCT system.

Mapping local optical axis in birefringent samples using polarization-sensitive optical coherence tomography.

An algorithm was developed to obtain depth-resolved local optical axis in birefringent samples by using conventional polarization-sensitive optical coherence tomography (PSOCT) that uses a single circularly polarized incident light. The round-trip sample Jones matrices were first constructed from the cumulative PSOCT results. An iterative method was then applied to construct the depth-resolved local Jones matrix from which the local optical axis was calculated.

Full-range spectral domain Jones matrix optical coherence tomography using a single spectral camera.

Jones matrix optical coherence tomography can fully characterize depth-resolved polarization properties in tissue. In this report, we described a simple single-camera based implementation of full-range spectral domain Jones matrix optical coherence tomography. The Jones matrix reconstruction algorithm was described in detail and system calibration was demonstrated with comprehensive examples.

Mapping local retardance in birefringent samples using polarization sensitive optical coherence tomography.

We proposed a method to extract depth-resolved local retardance in birefringent samples from conventional polarization-sensitive optical coherence tomography (PSOCT) that uses one circularly polarized incident light. Despite the wide use of such PSOCT systems in characterizing birefringent samples, the measured cumulative retardance does not represent the true cumulative retardance when optical axis varies with depth. A Jones calculus based algorithm was designed to derive the local depth-resolved retardance from conventional cumulative PSOCT results.

Path-length resolved reflectance in tendon and muscle.

Optical diffuse reflectance in fibrous tissues depends on measurement angles in relation to fiber orientation. In this study, path-length resolved optical reflectance was measured in tendon and skeletal muscle samples using a low-coherence Mach-Zehnder interferometer. The results show that the angular dependency in reflectance was eliminated in tendon tissue when representing reflectance as a function of mean path-length.

Correcting optical-axis calculation in polarization-sensitive optical coherence tomography.

Polarization-sensitive optical coherence tomography (PSOCT) has found many applications in imaging birefringence tissue samples. Polarization-sensitive detection is often implemented by utilizing a circularly polarized incident light and detecting the two orthogonal horizontal- and vertical-polarized interference components. However, the obtained optical axes images were inappropriately represented as depth-dependent periodic maps in all reported studies.

Single camera spectral domain polarization-sensitive optical coherence tomography using offset B-scan modulation.

We report a simple implementation to acquire spectral domain polarization-sensitive optical coherence tomography (PSOCT) using a single camera. By combining a dual-delay assembly in the reference arm and offset B-scan in the sample arm, the orthogonal vertical- and horizontal-polarized images were acquired in parallel and spatially separated by a fixed distance in the full range image space. The two orthogonal polarization images were recombined to calculate the intensity, retardance and fast-axis images.

Spectral domain polarization sensitive optical coherence tomography achieved by single camera detection.

We present a spectral domain polarization sensitive optical coherence tomography (PSOCT) system that incorporates: 1) a spectrometer configured with a single line-scan camera for spectral interferogram detection, 2) a reference delay line assembly that provides a fixed optical pathlength delay between the lights of two orthogonal polarization states, and 3) a moving reference mirror that introduces a constant modulation frequency in the spatial spectral interferograms while the probe beam is scanned over the sample. The system utilizes the full range of complex Fourier plane for polarization sensitive imaging, where OCT images formed by the vertical and horizontal polarization beam components appear adjacent to each other. It is able to provide imaging of retardation, fast optic axis and backscattered intensity of the interrogated biological tissue.