著者

Takashi Ida

出版者

American Institute of Physics

雑誌

REVIEW OF SCIENTIFIC INSTRUMENTS (ISSN:00346748)

巻号頁・発行日

vol.69, no.11, pp.3837-3839, 1998-11

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An efficient method for evaluating asymmetric diffraction peak profile functions based on the convolution of the Lorentzian or Gaussian function with any asymmetric window function is proposed. When this method is applied to approximate the convolution with the Howard’s window function [J. Appl. Crystallogr. 15, 615 (1982)], only a few terms of numerical integration give satisfactory results, even if the asymmetry is very strong.

著者

Nozokido T. Ishino M. Kudo H. Bae J.

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.84, no.3, pp.036103, 2013-03

被引用文献数

7

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Imaging of thermal radiation with a spatial resolution below the diffraction limit is demonstrated with a passive millimeter-wave microscope. This technique utilizes a sensitive radiometric receiver in combination with a scanning near-field microscope. Experiments were performed at 50 GHz (λ = 6 mm) with sample temperatures ranging from room temperature down to 160 K, and the performance was shown to be superior to that achieved with passive imaging systems in the infrared region. The images are affected by non-uniformities in the transmission of thermal radiation from the sample to the receiver via the near-field probe and the reflection of thermal radiation back to the receiver from the probe. The effects of these non-uniformities were successfully removed using a sample image acquired by active measurements using a vector network analyzer.

著者

Yoshikawa M. Yasuhara R. Morimoto M. Shima Y. Kohagura J. Sakamoto M. Nakashima Y. Imai T. Yamada I. Kawahata K. Funaba H. Minami T.

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.83, no.10, pp.10E333, 2012-10

被引用文献数

17 6

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In the GAMMA 10 tandem mirror, the typical electron density is comparable to that of the peripheral plasma of torus-type fusion devices. Therefore, an effective method to increase Thomson scattering (TS) signals is required in order to improve signal quality. In GAMMA 10, the yttrium-aluminum-garnet (YAG)-TS system comprises a laser, incident optics, light collection optics, signal detection electronics, and a data recording system. We have been developing a multi-pass TS method for a polarization-based system based on the GAMMA 10 YAG TS. To evaluate the effectiveness of the polarization-based configuration, the multi-pass system was installed in the GAMMA 10 YAG-TS system, which is capable of double-pass scattering. We carried out a Rayleigh scattering experiment and applied this double-pass scattering system to the GAMMA 10 plasma. The integrated scattering signal was made about twice as large by the double-pass system.

著者

Hojo H. Mase A.

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.77, no.10, pp.10F329, 2006-10

被引用文献数

1 1

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A new method for determining the electron density of a thin plasma by means of Fabry-Pérot interferometry is proposed. The interferometer consists of two plasma layers and dielectric material surrounded by two plasma layers. The transmittance of electromagnetic waves across the interferometer is calculated, and Fabry-Pérot resonances are demonstrated. It is shown that the electron density can be determined from the measurement of the Fabry-Pérot resonance frequencies. This method can also be applied to the measurement of conduction electron density in semiconductor films.

著者

Handa Shinya Domalain Thierry Kose Katsumi

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.78, no.8, pp.084705, 2007-08

被引用文献数

17 14

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An MRI pulse programmer has been developed using a single-chip microcontroller (ADμC7026). The microcontroller includes all the components required for the MRI pulse programmer: a 32-bit RISC CPU core, 62 Kbytes of flash memory, 8 Kbytes of SRAM, two 32-bit timers, four 12-bit DA converters, and 40 bits of general purpose I/O. An evaluation board for the microcontroller was connected to a host PC, an MRI transceiver, and a gradient driver using interface circuitry. Target (embedded) and host PC programs were developed to enable MRI pulse sequence generation by the microcontroller. The pulse programmer achieved a (nominal) time resolution of approximately 100 ns and a minimum time delay between successive events of approximately 9 μs. Imaging experiments using the pulse programmer demonstrated the effectiveness of our approach.

著者

Seki Yusuke Kandori Akihiko Kumagai Yukio Ohnuma Mitsuru Ishiyama Akihiko Ishii Tetsuko Nakamura Yoshiyuki Horigome Hitoshi Chiba Toshio

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.79, no.3, pp.036106, 2008-03

被引用文献数

11 14

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We developed a fetal magnetocardiography (fMCG) system that uses a pair of two-dimensional gradiometers to achieve high signal-to-noise ratio. The gradiometer, which is based on a low-Tc superconducting quantum interference device, detects the gradient of a magnetic field in two orthogonal directions. Gradiometer position is easy to adjust by operating the gantry to drive the cryostat in both the swinging and axial directions. As a result, a fMCG waveform for 25 weeks' gestation was measured under an unshielded environment in real time. Moreover, the P and T waves for 25 and 34 weeks' gestation, respectively, were obtained by averaging. These results indicate that this two-dimensional gradiometer is one of the most promising techniques for measuring fetal heart rate and diagnosing fetal arrhythmia.

著者

Handa Shinya Haishi Tomoyuki Kose Katsumi

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.79, no.11, pp.113706, 2008-11

被引用文献数

10 6

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A local radio frequency (rf) shielding consisting of a Cu plate and an LC balun circuit has been developed for a compact magnetic resonance imaging (MRI) system with a 0.3 T permanent magnet. Performance of the local rf shielding was evaluated using an artificial external noise source irradiating a human subject whose hand was inserted into the rf coil of the MRI system. Power spectra of the rf signal detected through the rf coil demonstrated that the local rf shield achieved 30.1 dB external noise suppression. With the local rf shielding, a MRI of the subject's hand was performed using a three-dimensional gradient-echo sequence. Anatomical structures of the subject's hand were clearly visualized. It was concluded that the local rf shielding could be used for the compact MRI system instead of a rf shielded room.

著者

Kimura Takeshi Geya Yuto Terada Yasuhiko Kose Katsumi Haishi Tomoyuki Gemma Hiroshi Sekozawa Yoshihiko

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.82, no.5, pp.053704, 2011-05

被引用文献数

48 12

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By combining a 0.3 T permanent magnet with flexible rotation and translation mechanism, a probe with a local electromagnetic shielding, several electrical units, a mobile lift, and an electric wagon, a mobile magnetic resonance imaging (MRI) system was developed for outdoor tree measurements. 2D cross-sectional images of normal and diseased branches of a pear tree were acquired for measurements of T1, T2, proton density, and apparent diffusion constant (ADC). The ADC map clearly differentiated diseased from normal branches. A whole-day measurement of the ADC map demonstrated that microscopic water flow in the normal branch changed proportionally with solar radiation. Therefore, we have concluded that our mobile MRI system is a powerful tool for studies of plants in outdoor environments.

著者

Sakakibara Jun Kita Junichiro Osato Naoyuki

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.83, no.3, pp.036103, 2012-03

被引用文献数

15

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We developed a video recording system with the capability of tracking moving objects and used it to track the flight of an insect. The system consists of two galvano mirrors, which redirect the light coming from the object in two orthogonal directions toward a high-speed camera to capture the image. An additional high-speed camera, which views the same object through a beam splitter placed between one of the galvano mirrors and the observation camera, detects the position of the object. The mirror angle is controlled to maintain the position of the object at the center of the view, allowing the object to be tracked. In order to validate this system, images of a live fly in flight were recorded along a flight path that was much longer than the field of view of the stationary camera. A high-resolution video image of a rapidly moving live fly was successfully captured.