Kin Pui Chan

Ultrahigh-resolution imaging of human donor cornea using full-field optical coherence tomography

A feasibility study of ultrahigh-resolution full-field optical coherence tomography (FF-OCT) for a subcellular-level imaging of human donor corneas is presented. The FF-OCT system employed in this experiment is based on a white light interference microscope, where the sample is illuminated by a thermal light source and a horizontal cross-sectional (en face) image is detected using a charge coupled device (CCD) camera. A conventional four-frame phase-shift detection technique is employed to extract the interferometric image from the CCD output. A 95-nm-broadband full-field illumination yields an axial resolution of 2.0 microm, and the system covers an area of 850 microm x 850 microm with a transverse resolution of 2.4 microm using a 0.3-NA microscope objective and a CCD camera with 512 x 512 pixels. Starting a measurement from the epithelial to the endothelial side, a series of en face images was obtained. From detected en face images, the epithelial cells, Bowmans layer, stromal keratocyte, nerve fiber, Descemets membrane, and endothelial cell were clearly observed. Keratocyte cytoplasm, its nuclei, and its processes were also separately detected. Two-dimensional interconnectivity of the keratocytes is visualized, and the keratocytes existing between collagen lamellaes are separately extracted by exploiting a high axial resolution ability of FF-OCT.

Real-Time, Micrometer Depth-Resolved Imaging by Low-Coherence Reflectometry and a Two-Dimensional Heterodyne Detection Technique

A novel two-dimensional heterodyne detection technique is demonstrated for real-time, cross-sectional imaging using optical coherence domain reflectometry without lateral scanning. The present technique, which is based on a frequency synchronous detection scheme, enables parallel heterodyne detection with an imager such as a charge coupled device camera. Full-field, micrometer-scale, depth-resolved images acquired at a rate of 10 frame/s are presented.

En-face optical coherence imaging for three-dimensional microscopy

En-face optical coherence tomography (OCT) employing parallel heterodyne detection technique is demonstrated for three-dimensional microscopy. To enable the use of commercially available CCD cameras as two-dimensional heterodyne detector arrays in OCT imaging, a frequency synchronous detection method is employed. Depth-resolved, full-field images are acquired at 30 Hz video-rate without lateral scanning.

Real-time optical coherence-domain reflectometry with an angular dispersion imaging scheme

Summary form only given. Optical coherence-domain reflectometry (OCDR) based on optical broadband interferometry is a powerful tool for micrometer-scale imaging in objects including miniature devices and recently biological tissues. In conventional OCDR, the image acquisition speed is limited by the scanning speed of the translating mirror. In this paper we demonstrate a non-scanning OCDR technique for real-time imaging.

Three-dimensional optical coherence tomography for biomedical diagnosis

We present three-dimensional optical coherence tomography with an imaging system capable of acquiring en-face images at a rate of 100 frames/s. In-vivo and in-vitro biological measurements are performed.

Spectroscopic measurement in turbid media by spectroscopic optical coherence tomography

We describe a parallel heterodyne detection method for real-time spectroscopic optical coherence tomography. Spectroscopic measurements using an ultrabroadband femtosecond Ti:sapphire laser has been carried out, demonstrating the feasibility of the present method.

Video-rate, full-field OCT imaging using a dual-channel parallel heterodyne detection technique

Full-field optical coherence tomography (OCT) is demonstrated using a parallel heterodyne detection technique with a pair of CCD cameras. A series of depth-resolved horizontal cross-sectional OCT images are acquired at 100 frames/s in a single longitudinal scan.

Non-Scanning Optical Coherence Tomography by an Angular Dispersion Imaging Method

Non-scanning optical coherence tomography based on off-axis interferometry has been developed for real-time depth-resolved imaging. By incorporating an angular-dispersion imaging scheme with a phase-shift detection technique, we show that amplitude of the interferogram corresponding to the reflectance of the sample can be detected directly with a CCD camera. Longitudinal cross-sectional images acquired at the rate of 5 Hz are presented.