All fiber polarization insensitive detection for spectrometer based optical coherence tomography using optical switch

Polarization dependent image artifacts are common in optical coherence tomography imaging. Polarization insensitive detection scheme for swept source based optical coherence tomography systems is well established but is yet to be demonstrated for all fiber spectrometer-based Fourier domain optical coherence tomography systems. In this work, we present an all fiber polarization insensitive detection scheme for spectrometer based optical coherence tomography systems. Images from chicken breast muscle tissue were acquired to demonstrate the effectiveness of this scheme for the conventional Fourier domain optical coherence tomography system

Experimental Demonstration of Spectral Intensity Optical Coherence Tomography

We demonstrate experimentally quantum-inspired, spectral-domain intensity optical coherence tomography. We show that the technique allows for both axial resolution improvement and dispersion cancellation compared to conventional optical coherence tomography. The method does not involve scanning and it works with classical light sources and standard photodetectors. The measurements are in excellent agreement with the theoretical predictions. We also propose an approach that enables the elimination of potential artifacts arising from multiple interfaces

Polarization-resolved second-harmonic-generation optical coherence tomography in collagen

We describe a novel imaging technique, second-harmonic-generation optical coherence tomography (SHOCT). This technique combines the spatial resolution and depth penetration of optical coherence tomography (OCT) with the molecular sensitivity of second-harmonic-generation spectroscopy. As a consequence of the coherent detection required for OCT, polarization-resolved images arise naturally. We demonstrate this new technique on a skin sample from the belly of Icelandic salmon, acquiring polarization-resolved SHOCT and OCT images simultaneously

Phase-dispersion optical tomography

We report on phase-dispersion optical tomography, a new imaging technique based on phase measurements using low-coherence interferometry. The technique simultaneously probes the target with fundamental and second-harmonic light and interferometrically measures the relative phase shift of the backscattered light fields. This phase change can arise either from reflection at an interface within a sample or from bulk refraction. We show that this highly sensitive 5 phase technique can complement optical coherence tomography, which measures electric field amplitude, by revealing otherwise undetectable dispersive variations in the sample

Second harmonic optical coherence tomography

Second harmonic optical coherence tomography, which uses coherence gating of second-order nonlinear optical response of biological tissues for imaging, is described and demonstrated. Femtosecond laser pulses were used to excite second harmonic waves from collagen harvested from rat tail tendon and a reference nonlinear crystal. Second harmonic interference fringe signals were detected and used for image construction. Because of the strong dependence of second harmonic generation on molecular and tissue structures, this technique offers contrast and resolution enhancement to conventional optical coherence tomography.Comment: 3 pages, 5 figures. Submitted on November 8, 2003, this paper has recently been accepted by Optics Letter

Phase-conjugate optical coherence tomography

Quantum optical coherence tomography (Q-OCT) offers a factor-of-two improvement in axial resolution and the advantage of even-order dispersion cancellation when it is compared to conventional OCT (C-OCT). These features have been ascribed to the non-classical nature of the biphoton state employed in the former, as opposed to the classical state used in the latter. Phase-conjugate OCT (PC-OCT), introduced here, shows that non-classical light is not necessary to reap Q-OCT's advantages. PC-OCT uses classical-state signal and reference beams, which have a phase-sensitive cross-correlation, together with phase conjugation to achieve the axial resolution and even-order dispersion cancellation of Q-OCT with a signal-to-noise ratio that can be comparable to that of C-OCT.Comment: 4 pages, 3 figure

Polarization-sensitive quantum-optical coherence tomography

We set forth a polarization-sensitive quantum-optical coherence tomography (PS-QOCT) technique that provides axial optical sectioning with polarization-sensitive capabilities. The technique provides a means for determining information about the optical path length between isotropic reflecting surfaces, the relative magnitude of the reflectance from each interface, the birefringence of the interstitial material, and the orientation of the optical axis of the sample. PS-QOCT is immune to sample dispersion and therefore permits measurements to be made at depths greater than those accessible via ordinary optical coherence tomography. We also provide a general Jones matrix theory for analyzing PS-QOCT systems and outline an experimental procedure for carrying out such measurements.Comment: 15 pages, 5 figures, to appear in Physical Review

Attenuation of the Ganglion Cell Layer in a Premature Infant Revealed with Handheld Spectral Domain Optical Coherence Tomography

Purpose: To report on subclinical retinal abnormalities shown through handheld spectral domain optical coherence tomography on a premature infant. Methods: Case report. Results: The initial and follow-up exams on a premature infant revealed severely attenuated ganglion cell and nerve fiber layers. There was cystoid macular edema in both eyes at the initial visits, which resolved by the 1-year follow-up. Discussion: Optical coherence tomography can reveal significant retinal abnormalities in premature infants which are not detectable through funduscopic exam. Documenting such findings may be useful for the comprehensive management of vision problems in children with a history of premature birth

Evaluation of a cheap ultrasonic stage for light source coherence function measurement, optical coherence tomography and dynamic focusing

We evaluate the performance of a cheap ultrasonic stage in setups related to optical coherence tomography. The stage was used in several configurations: (1) optical delay line in an optical coherence tomography (OCT) setup; (2) as a delay line measuring coherence function of a low coherence source (e. g. superluminescent diode) and (3) in a dynamic focusing arrangement. The results are as follows: the stage is suitable for coherence function measurement (coherence length up to 70 mu m) of the light source and dynamic focusing. We found it unsuitable for OCT due to an unstable velocity profile. Despite this, the velocity profile has a repeatable shape (4% over 1000 A-scans) and slight modifications to the stage promise wider applications