We present three dimensional (3D) imaging of macular diseases and glaucoma with high speed, Fourier domain optical coherence tomography (FD-OCT). Our FD-OCT system allows video rate cross-sectional imaging with 98 dB sensitivity and 4.3 μm depth-resolution in tissue. This performance results in high contrast sectional images that enhance visualization of fine retinal layers including external limiting membrane and of deep structure such as the choroid and optic nerve. Volume rendering of 3D OCT data set taken for 3.5 seconds provides realistic 3D images of macular, optic disc and their pathologic changes. This manuscript will show the methods for three dimensional FD-OCT including a raster scanning protocol for volume rendering and cancellation of the motion artifact of eye balls, and the application of the high contrast three dimensional OCT imaging to macular diseases and glaucoma in clinical examination.
We propose a new technique for obtaining three-dimensional phase distribution on differential interference contrast microscope to modulate relative phase retardation between two shear beams. Using partial coherent theory we extract the phase information from two different retardation images. For the object in a weak phase region, simple formula is derived. The images of nematomorph were obtained in vivo.
KEYWORDS: Optical coherence tomography, Skin, Image segmentation, In vivo imaging, Tomography, Image processing algorithms and systems, Detection and tracking algorithms, Light sources, Signal detection, Binary data
After segmentation of the epidermis from three-dimensional coherence tomography volume, a depth-oriented algorithm provides a segmentation of the infundibulum. In this process, the epidermal thickness, the population and the occupation ratio of the infundibula are provided.
KEYWORDS: Optical coherence tomography, Cameras, In vivo imaging, 3D acquisition, Spectroscopy, 3D image processing, Tissues, Camera shutters, Tomography, Visualization
A high-speed line-field Fourier-domain optical coherence tomography system has been developed. Tomographic images consisting of 656 A-lines are obtained at 121 frames per second. It is corresponding to 79,400 A-line/s. Three-dimensional volume sets consist of 256 OCT images are measured within 2.1 seconds. The sensitivity of this system is 79.5 dB. A biological tissue measurement is demonstrated with human nail fold in vivo. The three-dimensional nail fold structure is visualized.
We demonstrate 3-D optical coherence tomography using only 1-D mechanical scanning. This system uses the principle of Fourier domain optical coherence tomography for depth resolution, 1-D imaging for lateral vertical resolution, and mechanical scanning by a galvanometer for lateral horizontal resolution. An in vivo human fingerpad is investigated in three dimensions with an image size of 480 points (vertical) × 300 points (horizontal) × 1024 points (depth), which corresponds to 2.1×1.4×1.3 mm. The acquisition time for a single cross section is 1 ms and that for a single volume is 10 s. The system sensitivity is 75.6 dB at a probe beam power of 1.1 mW.
Standard high-speed Fourier domain optical coherence tomography
(FD-OCT) and a modified version of FD-OCT; a line-field FD-OCT
(LF-FDOCT) are demonstrated.
LF-FDOCT is using the principle of FD-OCT for its depth resolution and
a one-dimensional imaging optics for its one-dimensional lateral
resolution.
A mechanical C-scan drived by a galvano scanner is introduced into the
FD-FDOCT, which shows a cross sectional OCT image without any
mechanical scanning.
The improved version of FD-OCT visualizes the three-dimensional
structure of a sample with only one-dimensional scanning.
Both standard FD-OCT and LF-FDOCT are applied to dermatological
applications and visualize the inner structure of an in vivo
human fingerpad.
High speed complex full-range Fourier domain optical coherence tomography (FD-OCT) is demonstrated. In this FD-OCT phase modulation of a reference beam (M-scan) and transversal scanning (B-scan) are performed simultaneously. Because of this simultaneous BM-scan, this FD-OCT requires only a single A-scan for each single transversal position. The Fourier transform method is applied along the direction of the B-scan to reconstruct complex spectra, and the complex spectra compose a full-range OCT image. A simple but slow version of this FD-OCT visualizes the cross-section of a plastic plate. A modified fast version of this FD-OCT investigates a sweat duct in a finger pad in vivo, and visualizes it with 100 ms acquisition time.
A conventional Fourier-domain optical coherence tomography(FD-OCT) is improved to a line-field FD-OCT. The line-field FD-OCT is a conventional FD-OCT in its vertical axis, and a one-dimensional(1-D) imaging system in its lateral axis. Hence, depth and lateral information, which provide a 2-D OCT image, are simultaneously detected without any mechanical scan. Using an additional 1-D mechanical scan, which is realized by a galvano mirror in our system, a 3-D volume can be measured. Because the dimensions of mechanical scan are decreased compared with conventional FD-OCT, this system is capable of faster measurement.
A novel optical scheme for a full range Fourier domain optical coherence tomography (FD-OCT) is presented. This method avoids a mechanical scan for phase-shifting (mechanical M-scan) which enables a full range FD-OCT. A tilting reference wavefront is used to make variable phase offset of spectral interferometric fringes. Several spectral fringes are detected by a two dimensional CCD camera simultaneously. One axis of the CCD camera is occupied with the optical spectral axis, and the other axis is employed for phase offset variation. A few spectral fringes are extracted and used for phase-shifting algorithm. The principle of this system is confirmed with a plane mirror sample.
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