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Akihiro Fukuda

Bio: Akihiro Fukuda is an academic researcher from Osaka University. The author has contributed to research in topics: Eccrine sweat gland & Sweat gland. The author has an hindex of 2, co-authored 4 publications receiving 26 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, the authors developed a novel high-speed en face optical coherence tomography (OCT) system using a KTa1-xNbxO3 (KTN) optical beam deflector.
Abstract: We developed a novel high-speed en face optical coherence tomography (OCT) system using a KTa1–xNbxO3 (KTN) optical beam deflector. Using the imaging system, fast scanning was performed at 200 kHz by the KTN beam deflector, while slow scanning was performed at 400 Hz by the galvanometer mirror. In a preliminary experiment, we obtained en face OCT images of a human fingerprint at 400 fps. This is the highest speed reported in time-domain en face OCT imaging and is comparable to the speed of swept-source OCT. A 3D-OCT image of a sweat gland was also obtained by our imaging system.

21 citations

Journal ArticleDOI
TL;DR: In this article, a method for extraction of the specific eccrine sweat gland by means of the connected component extraction process and the adaptive threshold method, where the en face OCT images are constructed by the swept-source OCT.
Abstract: We have demonstrated dynamic analysis of the physiological function of eccrine sweat glands underneath skin surface by optical coherence tomography (OCT). In this paper, we propose a method for extraction of the specific eccrine sweat gland by means of the connected component extraction process and the adaptive threshold method, where the en face OCT images are constructed by the swept-source OCT. In the experiment, we demonstrate precise measurement of the volume of the sweat gland in response to the external stimulus.

9 citations

Journal ArticleDOI
TL;DR: In this article, a high-speed 3D optical coherence tomography (3D-OCT) system is developed, which is based on a high speed swept light source and a Mach-Zehnder interferometer with a highspeed photodetector.
Abstract: Three-dimensional (3D) optical coherence tomography (3D-OCT) has attracted attention for visualising complex structures in the biomedical field. In this reported work, a high-speed 3D-OCT system is developed, which is based on a high-speed swept light source and a Mach-Zehnder interferometer with a high-speed photodetector. The light source, incorporating a KTa1–x Nb x O3 electro-optic deflector, operates at a repetition rate of 200 kHz and enables high-speed data acquisition. As a preliminary study, images of a strawberry's surface have been obtained, two- and three-dimensionally. The 3D-OCT system has potential for the construction of a four-dimensional OCT image to dynamically display 3D-OCT images.

3 citations

Proceedings ArticleDOI
TL;DR: The dynamic analysis of the physiological function of eccrine sweat glands underneath skin surface by optical coherence tomography (OCT) and precise measurement of instantaneous volume of the sweat gland in response to the external stimulus are demonstrated.
Abstract: We have demonstrated dynamic analysis of the physiological function of eccrine sweat glands underneath skin surface by optical coherence tomography (OCT). We propose a method for extraction of the target eccrine sweat gland by use of the connected component extraction process and the adaptive threshold method, where the en-face OCT images are constructed by the SS-OCT. Furthermore, we demonstrate precise measurement of instantaneous volume of the sweat gland in response to the external stimulus. The dynamic change of instantaneous volume of eccrine sweat gland in mental sweating is performed by this method during the period of 300 sec with the frame intervals of 3.23 sec.

Cited by
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Journal Article
TL;DR: In this article, optical coherence tomography was adapted to allow high-speed visualization of tissue in a living animal with a catheter-endoscope 1 millimeter in diameter, which was used to obtain cross-sectional images of the rabbit gastrointestinal and respiratory tracts at 10-micrometer resolution.
Abstract: Current medical imaging technologies allow visualization of tissue anatomy in the human body at resolutions ranging from 100 micrometers to 1 millimeter. These technologies are generally not sensitive enough to detect early-stage tissue abnormalities associated with diseases such as cancer and atherosclerosis, which require micrometer-scale resolution. Here, optical coherence tomography was adapted to allow high-speed visualization of tissue in a living animal with a catheter-endoscope 1 millimeter in diameter. This method, referred to as "optical biopsy," was used to obtain cross-sectional images of the rabbit gastrointestinal and respiratory tracts at 10-micrometer resolution.

1,285 citations

Journal Article
TL;DR: In this article, the first in vivo measurements of human retinal structure with optical coherence tomography were presented, which represent the highest depth resolution in vivo retinal images to date.
Abstract: We describe what are to our knowledge the first in vivo measurements of human retinal structure with optical coherence tomography. These images represent the highest depth resolution in vivo retinal images to date. The tomographic system, image-processing techniques, and examples of high-resolution tomographs and their clinical relevance are discussed.

94 citations

Journal ArticleDOI
TL;DR: This study developed high-resolution OCM by using a high-power supercontinuum source in the 1700-nm spectral band, and compared the attenuation of signal-to-noise ratio between the 1800-nm and 1300-nm OCM imaging of a mouse brain under the condition of the same sensitivity.
Abstract: Optical coherence microscopy (OCM) is a label-free, high-resolution, three-dimensional (3D) imaging technique based on optical coherence tomography (OCT) and confocal microscopy. Here, we report that the 1700-nm spectral band has the great potential to improve the imaging depth in high-resolution OCM imaging of animal tissues. Recent studies to improve the imaging depth in OCT revealed that the 1700-nm spectral band is a promising choice for imaging turbid scattering tissues due to the low attenuation of light in the wavelength region. In this study, we developed high-resolution OCM by using a high-power supercontinuum source in the 1700-nm spectral band, and compared the attenuation of signal-to-noise ratio between the 1700-nm and 1300-nm OCM imaging of a mouse brain under the condition of the same sensitivity. The comparison clearly showed that the 1700-nm OCM provides larger imaging depth than the 1300-nm OCM. In this 1700-nm OCM, the lateral resolution of 1.3 μm and the axial resolution of 2.8 μm, when a refractive index was assumed to be 1.38, was achieved.

47 citations

Journal ArticleDOI
TL;DR: A three orders-of-magnitude increase in the speed of a space-charge-controlled KTN beam deflector achieved by eliminating the electric field-induced phase transition (EFIPT) in a nanodisordered KTN crystal is reported.
Abstract: In this paper, we report a three orders-of-magnitude increase in the speed of a space-charge-controlled KTN beam deflector achieved by eliminating the electric field-induced phase transition (EFIPT) in a nanodisordered KTN crystal. Previously, to maximize the electro-optic effect, a KTN beam deflector was operated at a temperature slightly above the Curie temperature. The electric field could cause the KTN to undergo a phase transition from the paraelectric phase to the ferroelectric phase at this temperature, which causes the deflector to operate in the linear electro-optic regime. Since the deflection angle of the deflector is proportional to the space charge distribution but not the magnitude of the applied electric field, the scanning speed of the beam deflector is limited by the electron mobility within the KTN crystal. To overcome this speed limitation caused by the EFIPT, we propose to operate the deflector at a temperature above the critical end point. This results in a significant increase in the scanning speed from the microsecond to nanosecond regime, which represents a major technological advance in the field of fast speed beam scanners. This can be highly beneficial for many applications including high-speed imaging, broadband optical communications, and ultrafast laser display and printing.

34 citations

Journal ArticleDOI
TL;DR: This work provides an effective way for realizing multi-dimensional high-speed non-mechanical beam deflection, which can be very useful for a variety of applications, including high- speed 3D laser printing, high resolution high speed scanning imaging, and free space reconfigurable laser communications.
Abstract: In this paper, a high-speed non-mechanical two-dimensional KTN beam deflector is reported. The scanning mechanism is based on the combination of space charge controlled beam deflection and temperature gradient enabled beam deflection in a nanodisordered KTN crystal. Both theoretical analyses and experimental investigations are provided, which agree relatively well with each other. This work provides an effective way for realizing multi-dimensional high-speed non-mechanical beam deflection, which can be very useful for a variety of applications, including high-speed 3D laser printing, high resolution high speed scanning imaging, and free space reconfigurable laser communications.

20 citations