Gouki Aoki

Simultaneous B-M-mode scanning method for real-time full-range Fourier domain optical coherence tomography.

High-speed complex full-range Fourier domain optical coherence tomography (FD-OCT) is demonstrated. In this FD-OCT, the phase modulation of a reference beam (M scan) and transversal scanning (B scan) are simultaneously performed. The Fourier transform method is applied along the direction of the B scan to reconstruct complex spectra, and the complex spectra comprise a full-range OCT image. Because of this simultaneous B-M-mode scan, the FD-OCT requires only a single A scan for each single transversal position to obtain a full-range FD-OCT image. A simple but slow version of the 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 an acquisition time of 27 ms.

One-shot-phase-shifting Fourier domain optical coherence tomography by reference wavefront tilting

A novel optical scheme for a phase shifting method of Fourier domain optical coherence tomography is presented. With this method we avoid a mechanical scan for phase shifting (mechanical M-scan) by using a reference beam with tilted wavefront. The principle of this system is confirmed with a simple mirror object. This method is applied on a biological sample and used to investigate a porcine anterior eye chamber.

Three-dimensional line-field Fourier domain optical coherence tomography for in vivo dermatological investigation

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) x 300 points (horizontal) x 1024 points (depth), which corresponds to 2.1 x 1.4 x 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.

Clinical application of high-contrast three-dimensional imaging of the retina, choroid, and optic nerve with three-dimensional Fourier domain optical coherence tomography

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.

High-speed full-range Fourier domain optical coherence tomography by simultaneous B-M-mode scanning

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.

Three-dimensional measurement of microorganism by retardation modulated differential interference contrast microscope

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.

Three-dimensional evaluation of in vivo human skin by spectral domain and swept source optical coherence tomography

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.

Standard and Line-Field Fourier Domain Optical Coherence Tomography

Standard Fourier domain optical coherence tomography (FD-OCT) and line-field Fourier domain optical coherence tomography (LF-FDOCT) are described. The standard FD-OCT has the measurement speed of 36 frames/sec and one frame consisting 500 A-scans. The LF-FDOCT is an improved version of FD-OCT and determines a cross section of a sample without any mechanical scanning. The LF-FDOCT has the measurement speed of 30 frames/sec, which is corresponding to 480 KH/ A-scan. A galvano-meter is introduced into the LF-FDOCT and it enables three-dimensional OCT measurement with only one-dimensional mechanical scanning

In vivo human retinal imaging using high-speed Doppler Fourier-domain optical coherence tomography

We develop high-speed Fourier-domain optical coherence tomography. A-scan rate is 18700 Hz and system sensitivity is 90.3 dB with –50.3 dB reflector. In vivo human retinal structure and blood flow imaging are demonstrated.

Dermatological Investigation by Three-Dimensional Line-Field Fourier Domain Optical Coherence Tomography

Three-dimensional optical coherence tomography using only one-dimensional mechanical scanning is demonstrated. This system uses the principle of Fourier domain optical coherence tomography for depth resolution, one-dimensional imaging for lateral vertical resolution, and mechanical scanning by a galvanometer for lateral horizontal resolution. An in vivo human fingerpad is investigated three-dimensionally. The acquisition time for a single cross section is 1 ms and that for a single volume is 10 s, and the system sensitivity is 75.6 dB.