The effects of cooling, laser irradiation, and laser irradiation with cooling on blood vessels were investigated with Color Doppler Optical Coherence Tomography (CDOCT). CDOCT may contribute to an understanding of the dynamics of laser-blood vessel interactions and aid in better optimization of laser parameters to be used. In this study, hamster dorsal skin flap window vessels were irradiated with a KTP laser operating at 532 nm. Irradiation sites were imaged with CDOCT prior to, during, immediately after, and several days after irradiation. KTP laser parameters were: radiant exposures in the range of 7-14 J/cm2, 3 mm spot size, and 10 ms pulse duration. Magnitude and color Doppler images provided information such as vessel size, depth, and changes in blood flow velocity. Vessel constriction, temporary occlusion, and changes in flow were frequent results of laser irradiation visualized with CDOCT. In addition, the effects of cooling alone were imaged with CDOCT and its effects on blood vessel flow and morphology were investigated before and after laser irradiation.

We present an all-fiber, compact device for optical frequency-domain reflectometry (OFDR). The device combines a Michelson interferometer with a fiber Fabry-Perot tunable filter for rapid wavelength scanning. The free spectral range of the filter is 32 nm and scans may be completed in less than 2.5 ms. Images of the surface geometry of the material under study can be reconstructed at scan rates up to 400 Hz with an axial resolution of 20 μm.

Polarization sensitive optical coherence tomography (PS-OCT) was used to determine the depth resolved Stokes parameters of light backscattered from highly scattering biological samples. Through simultaneous detection of the amplitude and relative phase of signal fringes in orthogonal polarization states formed by interference of light backscattered from turbid media and a mirror in the reference arm of a Michelson interferometer, changes in the Stokes parameters due to the optical phase delay between light propagating along the fast and slow axes of birefringent media were measured. Inasmuch as fibrous structures in many biological tissues influence the polarization state of light backscattered. PS-OCT is a potentially useful technique to image the structural properties of turbid biological materials. The method can also be applied to the investigation of birefringent properties in highly scattering materials such as ceramics and crystals.

We demonstrate a high-speed and wide-tuning-range swept laser for optical coherence tomography (OCT) imaging. The repetition rate of the laser is twice the speed of the polygon filter and is achieved by using two delay fibers in a Fox-Smith cavity. The performance of the laser is the following: a scanning range of 110nm centered at 1310nm, and the output power of 10mw at a 102.2 kHz sweeping rate. © 2011 Copyright SPIE - The International Society for Optical Engineering.

In this paper, we analyzed the retinal and choroidal blood vasculature in the posterior segment of the human eye with optimized color Doppler and Doppler variance optical coherence tomography. Depth-resolved structure, color Doppler and Doppler variance images were compared. Blood vessels down to capillary level were able to be obtained with the optimized optical coherence color Doppler and Doppler variance method. For in-vivo imaging of human eyes, bulkmotion induced bulk phase must be identified and removed before using color Doppler method. It was found that the Doppler variance method is not sensitive to bulk motion and the method can be used without removing the bulk phase. A novel, simple and fast segmentation algorithm to indentify retinal pigment epithelium (RPE) was proposed and used to segment the retinal and choroidal layer. The algorithm was based on the detected OCT signal intensity difference between different layers. A spectrometer-based Fourier domain OCT system with a central wavelength of 890 nm and bandwidth of 150nm was used in this study. The 3-dimensional imaging volume contained 120 sequential two dimensional images with 2048 A-lines per image. The total imaging time was 12 seconds and the imaging area was 5x5 mm2. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

A polarization maintaining buffered Fourier domain mode-locked (FDML) swept source at center wavelength of 1310 nm for multiplying the scanning rate of FDML swept source was demonstrated. The scanning rate of the buffered FDML swept source was doubled without sacrificing the output power of the swept source by combining two orthogonally polarized outputs with a polarization beam combiner (PBC). The stability of the swept source was improved significantly because the polarization state of the laser beam inside the cavity is maintained without any polarization controllers. With the linear polarization states of the output laser beam, the buffered FDML swept source is also ready to be used in a PSOCT system. The swept source is capable of a tuning range of more than 150 nm at a 102 kHz sweeping rate. An FDOCT system was developed with the built swept source. © 2012 SPIE.

Adaptive optics - optical coherence tomography (AO-OCT) has the potential to improve lateral resolution for OCT retinal imaging. Several reports have already described the successful combination of AO with a scanning confocal Fourier-domain OCT instrument to permit real-time three-dimensional (3D) imaging with high resolution (in all three dimensions). One of the key components that sets the performance limit of AO is the wavefront corrector. Several different wavefront correctors have been used in AO-OCT systems so far. In this paper we compare two commercially available wavefront correctors: an AOptix Bimorph deformable mirror (DM) and a Boston Micromachines Micro-Electro Mechanical System (MEMS) DM (used for the first time in an AO-OCT system). To simplify the analysis, we tested their performance for the correction of low-amplitude high-order aberrations (with minimal defocus and astigmatism). Results were obtained with an AO-OCT instrument constructed at UC Davis that combines state-of-the-art Fourier-domain OCT and an AO design to allow simultaneous testing of both mirrors without the need to modify the optical system.

We evaluated several, previously published, complex conjugate artifact removal methods and algorithms that have been proposed for Fourier domain optical coherence tomography (Fd-OCT). To ensure comparable conditions, only one OCT system was used, but with modified data acquisition schemes, depending on the requirements of each method/algorithm. This limited our evaluation to single spectrometer based Fd-OCT approaches. The suppression ratio of complex conjugate artifact images using a paperboard is assessed for all tested methods. Several other metrics are also used for comparison, including a list of additional hardware requirements (beyond standard Fd-OCT components) and data acquisition schemes. Finally, in vivo human finger pad and nail images are presented for comparison to the standard Fd- OCT images and full-range images. © 2010 Copyright SPIE - The International Society for Optical Engineering.