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2. Super-resolution discrete-Fourier-transform spectroscopy using precisely periodic radiation beyond time window size limitation

Author

Yasui, Takeshi, Iyonaga, Yuki, Hsieh, Yi-Da, Sakaguchi, Yoshiyuki, Hindle, Francis, Yokoyama, Shuko, Araki, Tsutomu, and Hashimoto, Mamoru

Subjects
Physics - Optics
Abstract

Fourier transform spectroscopy (FTS) has been widely used in a variety of fields in research, industry, and medicine due to its high signal-to-noise ratio, simultaneous acquisition of signals in a broad spectrum, and versatility for different radiation sources. Further improvement of the spectroscopic performance will widen its scope of applications. Here, we demonstrate improved spectral resolution by overcoming the time window limitation using discrete Fourier transform spectroscopy (dFTS) with precisely periodic pulsed terahertz (THz) radiation. Since infinitesimal resolution can be achieved at periodically discrete frequencies when the time window size is exactly matched to the repetition period T, a combination of THz-dFTS with a spectral interleaving technique achieves a spectral resolution only limited by the spectral interleaving interval. Linewidths narrower than 1/(50T) are fully resolved allowing the attribution of rotational-transition absorption lines of low-pressure molecular gases within a 1.25 MHz band. The proposed method represents a powerful tool to improve spectrometer performance and accelerate the practical use of various types of FTS., Comment: 26 pages, 5 figures

Published
2014
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3. Adaptive sampling dual terahertz comb spectroscopy using free-running dual femtosecond lasers

Author

Yasui, Takeshi, Ichikawa, Ryuji, Hsieh, Yi-Da, Hayashi, Kenta, Cahyadi, Harsono, Hindle, Francis, Sakaguchi, Yoshiyuki, Iwata, Tetsuo, Mizutani, Yasuhiro, Yamamoto, Hirotsugu, Minoshima, Kaoru, and Inaba, Hajime

Subjects
Physics - Optics
Abstract

Dual terahertz (THz) comb spectroscopy is a promising methods for high accuracy, high resolution, and broadband THz spectroscopy because the mode-resolved THz comb spectrum possesses both characteristics of broadband THz radiation and narrow-linewidth continuous-wave THz radiation and all frequency mode of THz comb can be phase-locked to a microwave frequency standard. However, requirement of stabilized dual femtosecond lasers has often hindered wide use of this method. In this article, we demonstrated the adaptive sampling, dual THz comb spectroscopy, enabling use of free-running dual femtosecond lasers. To correct the non-linearity of time and frequency scale caused by the laser timing jitter, an adaptive sampling clock is generated by dual THz-comb-referenced spectrum analysers and is used for a timing signal in a data acquisition board. The demonstrated results did not only indicate the implementation of dual THz comb spectroscopy with free-running dual lasers but also implied the superiority of its spectroscopic performance over the dual THz comb spectroscopy with stabilized dual lasers., Comment: 28 pages, 6 figures

Published
2014
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4. Gapless dual-comb spectroscopy in terahertz region

Author

Yasui, Takeshi, Hsieh, Yi-Da, Iyonaga, Yuki, Sakaguchi, Yoshiyuki, Yokoyama, Shuko, Inaba, Hajime, Minoshima, Kaoru, Hindle, Francis, and Araki, Tsutomu

Subjects
Physics - Optics
Abstract

We demonstrated combination of gapless terahertz (THz) comb with dual-comb spectroscopy, namely gapless dual-THz-comb spectroscopy, to achieve the spectral resolution equal to width of the THz comb tooth. The gapless THz comb was realized by interpolating frequency gaps between the comb teeth with sweeping of a laser mode-locked frequency. The demonstration of low-pressure gas spectroscopy with gapless dual-THz-comb spectroscopy clearly indicated that the spectral resolution was decreased down to 2.5-MHz width of the comb tooth and the spectral accuracy was enhanced to 10-6 within the spectral range of 1THz. The proposed method will be a powerful tool to simultaneously achieve high resolution, high accuracy, and broad spectral coverage in THz spectroscopy., Comment: 12 pages, 4 figures

Published
2013
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6. Epitaxial growth of NbN on an ultrathin MgO/semiconductor system.

Author

Tonouchi, Masayoshi, Sakaguchi, Yoshiyuki, and Kobayashi, Takeshi

Subjects
*EPITAXY, *NIOBIUM compounds, *SEMICONDUCTORS
Abstract

Studies the epitaxial growth of niobium nitrogen (NbN) on an ultathin manganese oxide semiconductor system. Potential applications of niobium and niobium nitrogen; Details on the experimental procedure; Discussion on the results of the study.

Published
1987
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7. Adaptive sampling dual terahertz comb spectroscopy using dual free-running femtosecond lasers

Author

Yasui, Takeshi, Ichikawa, Ryuji, Hsieh, Yi-Da, Hayashi, Kenta, Cahyadi, Harsono, Hindle, Francis, Sakaguchi, Yoshiyuki, Iwata, Tetsuo, Mizutani, Yasuhiro, Yamamoto, Hirotsugu, Minoshima, Kaoru, Inaba, Hajime, Yasui, Takeshi, Ichikawa, Ryuji, Hsieh, Yi-Da, Hayashi, Kenta, Cahyadi, Harsono, Hindle, Francis, Sakaguchi, Yoshiyuki, Iwata, Tetsuo, Mizutani, Yasuhiro, Yamamoto, Hirotsugu, Minoshima, Kaoru, and Inaba, Hajime

Abstract

Terahertz (THz) dual comb spectroscopy (DCS) is a promising method for high-accuracy, high-resolution, broadband THz spectroscopy because the mode-resolved THz comb spectrum includes both broadband THz radiation and narrow-line CW-THz radiation characteristics. In addition, all frequency modes of a THz comb can be phase-locked to a microwave frequency standard, providing excellent traceability. However, the need for stabilization of dual femtosecond lasers has often hindered its wide use. To overcome this limitation, here we have demonstrated adaptive-sampling THz-DCS, allowing the use of free-running femtosecond lasers. To correct the fluctuation of the time and frequency scales caused by the laser timing jitter, an adaptive sampling clock is generated by dual THz-comb-referenced spectrum analysers and is used for a timing clock signal in a data acquisition board. The results not only indicated the successful implementation of THz-DCS with free-running lasers but also showed that this configuration outperforms standard THz-DCS with stabilized lasers due to the slight jitter remained in the stabilized lasers.

Published
2015

8. Adaptive sampling dual terahertz comb spectroscopy using dual free-running femtosecond lasers

Author

Yasui, Takeshi, primary, Ichikawa, Ryuji, additional, Hsieh, Yi-Da, additional, Hayashi, Kenta, additional, Cahyadi, Harsono, additional, Hindle, Francis, additional, Sakaguchi, Yoshiyuki, additional, Iwata, Tetsuo, additional, Mizutani, Yasuhiro, additional, Yamamoto, Hirotsugu, additional, Minoshima, Kaoru, additional, and Inaba, Hajime, additional

Published
2015
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14. Terahertz Comb Spectroscopy Traceable to Microwave Frequency Standard

Author

Hsieh, Yi-Da, primary, Iyonaga, Yuki, additional, Sakaguchi, Yoshiyuki, additional, Yokoyama, Shuko, additional, Inaba, Hajime, additional, Minoshima, Kaoru, additional, Hindle, Francis, additional, Takahashi, Yoshinori, additional, Yoshimura, Masashi, additional, Mori, Yusuke, additional, Araki, Tsutomu, additional, and Yasui, Takeshi, additional

Published
2013
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15. Gapless THz Comb Spectroscopy

Author

Yasui, Takeshi, primary, Hsieh, Yi-Da, additional, Iyonaga, Yuki, additional, Sakaguchi, Yoshiyuki, additional, Yokoyama, Shuko, additional, Inaba, Hajime, additional, Minoshima, Kaoru, additional, and Araki, Tsutomu, additional

Published
2013
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16. 布の力学特性を用いた衣服形状の動的計算方法

Author

Sakaguchi, Yoshiyuki, 池田, 克夫, 石田, 亨, and 美濃, 導彦

Abstract

本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものである

Published
1997

23. Lace curtain

Author

Uno, Hitoshi, primary, Mizushima, Yoshiki, additional, Nagata, Noriko, additional, and Sakaguchi, Yoshiyuki, additional

Published
2008
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25. Leather texture generation

Author

Miyata, Kazunori, primary, Sakaguchi, Yoshiyuki, additional, Imao, Koji, additional, Hatada, Yoshitake, additional, Fujita, Atsushi, additional, and Suzaki, Ryotaro, additional

Published
2006
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43. A New Apparatus for the Study of Fabric Drape.

Author

Mitzutani, Chiyomi, Amano, Toshihiko, and Sakaguchi, Yoshiyuki

Subjects
TEXTILE industry, MANUFACTURING processes, TESTING equipment, MACHINERY, INDUSTRIAL equipment
Abstract

A new drape elevator is developed to analyze the drape generation mechanism. The drape elevator can measure drape shape, including node generation at various stages during drape formation. The drape elevator method indicates better reproducibility of the drape coefficient of the fabrics than the conventional method. The drape formation process is experimentally found to consist of three stages, seeds generation, their development, and the final stabilizing stages. A new parameter R, evaluating the shape of the drape, is defined in terms of the drape projection. Both the R parameter and the drape coefficient are expected to be useful parameters for the quantitative analysis of fabric drape formation. [ABSTRACT FROM AUTHOR]

Published
2005
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49. A New Apparatus for the Study of Fabric Drape.

Author

Mizutani, Chiyomi, Amano, Toshihiko, and Sakaguchi, Yoshiyuki

Abstract

A new drape elevator is developed to analyze the drape generation mechanism. The drape elevator can measure drape shape, including node generation at various stages during drape formation. The drape elevator method indicates better reproducibility of the drape coefficient of the fabrics than the conventional method. The drape formation process is experimentally found to consist of three stages, seeds generation, their development, and the final stabilizing stages. A new parameter R, evaluating the shape of the drape is defined in terms of the drape projection. Both the R parameter and the drape coefficient are expected to be useful parameters for the quantitative analysis of fabric drape formation. [ABSTRACT FROM AUTHOR]

Published
2005

50. Heteroepitaxial Growth of SrBi4Ti4O15/Bi2Sr2CuO6+yStructure by ArF Excimer Laser Ablation

Author

Tachiki, Minoru, Matsutani, Masahiro, Fujii, Tatsuhiko, Sakaguchi, Yoshiyuki, and Takeshi Kobayashi, Takeshi Kobayashi

Abstract

Heteroepitaxial SrBi4Ti4O15/Bi2Sr2CuO6+ythin films were grown on (100)MgO substrates by the excimer laser ablation method. X-ray, reflection high-energy electron and low-energy electron diffraction (XRD, RHEED and LEED) revealed the epitaxial ordering of deposited film crystal oriented normal to the substrate surface, though the streak patterns were slightly dim. The permittivity of SrBi4Ti4O15film was obtained as 120 ?0from C-Vmeasurement for Al/SrBi4Ti4O15/Bi2Sr2CuO6+yparallel plate capacitor.

Published
1995
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