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185 results on '"Hiromoto, Norihisa"'

2. The Far-Infrared Surveyor (FIS) for AKARI

Author

Kawada, Mitsunobu, Baba, Hajime, Barthel, Peter D., Clements, David, Cohen, Martin, Doi, Yasuo, Figueredo, Elysandra, Fujiwara, Mikio, Goto, Tomotsugu, Hasegawa, Sunao, Hibi, Yasunori, Hirao, Takanori, Hiromoto, Norihisa, Jeong, Woong-Seob, Kaneda, Hidehiro, Kawai, Toshihide, Kawamura, Akiko, Kester, Do, Kii, Tsuneo, Kobayashi, Hisato, Kwon, Suk Minn, Lee, Hyung Mok, Makiuti, Sin'itirou, Matsuo, Hiroshi, Matsuura, Shuji, Müller, Thomas G., Murakami, Noriko, Nagata, Hirohisa, Nakagawa, Takao, Narita, Masanao, Noda, Manabu, Oh, Sang Hoon, Okada, Yoko, Okuda, Haruyuki, Oliver, Sebastian, Ootsubo, Takafumi, Pak, Soojong, Park, Yong-Sun, Pearson, Chris P., Rowan-Robinson, Michael, Saito, Toshinobu, Salama, Alberto, Sato, Shinji, Savage, Richard S., Serjeant, Stephen, Shibai, Hiroshi, Shirahata, Mai, Sohn, Jungjoo, Suzuki, Toyoaki, Takagi, Toshinobu, Takahashi, Hidenori, Thomson, Matthew, Usui, Fumihiko, Verdugo, Eva, Watabe, Toyoki, White, Glenn J., Wang, Lingyu, Yamamura, Issei, Yamamuchi, Chisato, and Yasuda, Akiko

Subjects
Astrophysics
Abstract

The Far-Infrared Surveyor (FIS) is one of two focal plane instruments on the AKARI satellite. FIS has four photometric bands at 65, 90, 140, and 160 um, and uses two kinds of array detectors. The FIS arrays and optics are designed to sweep the sky with high spatial resolution and redundancy. The actual scan width is more than eight arcmin, and the pixel pitch is matches the diffraction limit of the telescope. Derived point spread functions (PSFs) from observations of asteroids are similar to the optical model. Significant excesses, however, are clearly seen around tails of the PSFs, whose contributions are about 30% of the total power. All FIS functions are operating well in orbit, and its performance meets the laboratory characterizations, except for the two longer wavelength bands, which are not performing as well as characterized. Furthermore, the FIS has a spectroscopic capability using a Fourier transform spectrometer (FTS). Because the FTS takes advantage of the optics and detectors of the photometer, it can simultaneously make a spectral map. This paper summarizes the in-flight technical and operational performance of the FIS., Comment: 23 pages, 10 figures, and 2 tables. Accepted for publication in the AKARI special issue of the Publications of the Astronomical Society of Japan

Published
2007
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8. Performance improvement of on-chip integrable terahertz microbolometer arrays using nanoscale meander titanium thermistor.

Author

Banerjee, Amit, Satoh, Hiroaki, Elamaran, Durgadevi, Sharma, Yash, Hiromoto, Norihisa, and Inokawa, Hiroshi

Subjects
BOLOMETERS, NANOTECHNOLOGY, TITANIUM, ANTENNAS (Electronics), MICROMACHINING, MAGNETIC coupling
Abstract

In this study, uncooled antenna-coupled microbolometer arrays were fabricated to detect terahertz waves by using nanoscale meander-shaped Ti thermistors with design widths of DW = 0.1 and 0.2 μm, respectively, on SiO2 and SiNx substrates. Each unit device with a thermistor with DW = 0.1 μm yielded double the electrical responsivity (787 V/W) of unit devices with thermistors with DW = 0.2 μm (386 V/W) at the maximum allowable bias current (Ib = 50 for DW = 0.1 μm and 100 μA for DW = 0.2 μm, respectively). However, the calculated noise-equivalent power (NEP) of unit devices with thermistors with DW = 0.1 μm was 1.85 × 10 − 10 W / Hz at Ib = 50 μA and 1.58 × 10 − 10 W / Hz at Ib = 100 μA for unit devices with thermistors with DW = 0.2 μm. Hence, the reduction in DW did not lead to an improvement in NEP. This study validates our previous investigation into the effect of width on such device parameters such as the temperature coefficient of resistance (TCR) and resistivity in the context of device miniaturization. The smaller grain size in thinner metal interconnects (thermistors) can be linked to the lower TCR and increased resistivity of the devices. Thus, the enhancement in responsivity in the design was largely due to the nanoscale meander design that, however, was detrimental to the noise response of the devices. These devices with nanoscale Ti meander thermistors deliver high responsivity in unit devices with scope for further miniaturization and have significant potential for application as on-chip integrable detector arrays. [ABSTRACT FROM AUTHOR]

Published
2019
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14. Terahertz-wave antireflection coating on Ge and GaAs with fused quartz

Author

Kawase, Kodo and Hiromoto, Norihisa

Subjects
Optical coatings -- Production processes, Plastic films -- Production processes, Astronomy, Physics
Abstract

In the terahertz-wave region, fabrication of an antireflection (AR) coating is difficult because it must be as thick as several tens of micrometers, which is far thicker than that used in the optical region. We discuss a lapping method for fabricating an AR layer with a desired thickness for terahertz-wave optical devices. To demonstrate this method, we glued a thin fused-quartz plate to a surface of an undoped Ge or GaAs wafer and polished it tea thickness of one-quarter wavelength. This reduced the reflectivity of the AR surface to 1/720 of the reflection of an uncoated surface, as expected from optical theory.

Published
1998

15. Asbestos real-time monitor in an atmospheric environment

Author

Hiromoto, Norihisa, Hashiguchi, Kosei, Ito, Shigeo, and Itabe, Toshikazu

Subjects
Asbestos fibers -- Research, Light scattering -- Research, Polarization (Light) -- Research, Aerosols -- Research, Astronomy, Physics
Abstract

The concentration of asbestos fiber aerosols can be monitored by measuring the polarization of laser light scattered by asbestos fibers. The principle of discriminating asbestos fibers is based on the theoretically expected difference in polarization at a scattering angle of 170 deg between cylindrical and spherical airborne particles; polarization at this scattering angle should be positive for cylindrical particles such as asbestos fibers but should be negative or close to zero for spherical mineral particles. We constructed an experimental asbestos real-time monitor that uses a strong electric field to align the airborne particles, that uses lasers having linear polarization with an equal amplitude in parallel and perpendicular components to the aligned long axis of particles, and that simultaneously detects the two components of the linear polarization of light scattered at 170 deg, i.e., close to the backscatter. Experiments that were performed to detect the light scattered from airborne standard asbestos fibers showed that the measured polarization fits theoretical prediction. The concentrations of airborne asbestos fibers obtained by the asbestos real-time monitor were consistent with those estimated by the standard phase contrast microscope method. Key words: Asbestos fibers, light scattering, polarization, cylindrical particles, aerosols.

Published
1997

31. Evaluation of Cryogenic Readout Circuits with GaAs JFETs for Far-Infrared Detectors

Author

OKUMURA, Kenichi and HIROMOTO, Norihisa

Abstract

The characteristics of gallium arsenide junction field-effect transistors (GaAs JFETs)and the performance of cryogenic readout circuits using GaAs JFETs for two-dimensional far-infrared arrays are evaluated at cryogenic temperature. We fabricated the GaAs JFETs withvarious gate sizes ranging from W/L = 5μm/0.5μm to 200μm/200μm to systematically measuretheir static characteristics and low-frequency noise spectra. We found that the low-frequency noisevoltage depends on the device size in the saturation region of GaAs JFETs at 4.2 K, and the powerdensity of the noise voltage is inversely proportional to the gate area. These findings allowed usto determine the Hooge parameter of the GaAs JFET at 4.2 K to be 4×10-5, assuming that thecarrier mobility is 1.5×10+3 cm2/Vs. On the other hand, we did not find the obvious correlationbetween the low-frequency noise and gate size in the ohmic region of GaAs JFETs. Based on thesemeasurements for GaAs JFETs, we fabricated and tested a dual GaAs JFET, a source-follower-per-detector (SFD) circuit, and a 20×3 channel SFD circuit array. The Common-Mode-Rejection-Ratio(CMRR) of the dual GaAs JFET with W/L = 50μm/20μm at 4.2 K was determined to be 40-60dB under small power dissipation. The performance of SFD circuits and the 20×3 channel SFDarrays for two-dimensional far-infrared Ge:Ga detector readouts are currently being evaluated., 資料番号: SA4618377000

Published
2000

32. Compact Two-Dimensional Array of Stressed GE:GA Detectors

Author

Doi, Yasuo, Makiuti, Shin'ichiro, Okuda, Haruyuki, Nakagawa, Takao, Shibai, Hiroshi, Kawada, Mitsunobu, Hiromoto, Norihisa, Fujiwara, Mikio, and Okumura, Kenichi

Abstract

Accepted: 1999-02-08, 資料番号: SA1001842000

Published
2000

33. FIS: far-infrared surveyor onboard ASTRO-F (IRIS)

Author

Takahashi, Hidenori, Shibai, Hiroshi, Kawada, Mitsunobu, Hirao, Takanori, Watabe, Toyoki, Tsuduku, Yasushi, Nagata, Hirohisa, Utsuno, Hiroshi, Hibi, Yasushi, Hirooka, Shinya, Nakagawa, Takao, Kaneda, Hidehiro, Matsuura, Shuji, Kii, Tsuneo, Makiuti, Shin'ichiro, Okamura, Yoshihiko, Doi, Yasuo, Matsuo, Hiroshi, Hiromoto, Norihisa, Fujiwara, Mikio, and Noda, Manabu

Abstract

著者人数：21名, 資料番号: SA1001812000

Published
2000

35. The IRTS (Infrared Telescope in Space) Mission

Author

Ganga, Ken, Guo, Hongfeng, Murakami, Hiroshi, Freund, Minoru M., Hirao, Takanori, Hiromoto, Norihisa, Kawada, Mitsunobu, Lange, Andrew E., Makiuti, Sin'itirou, Matsuhara, Hideo, Matsumoto, Toshio, Matsuura, Shuji, Murakami, Masahide, Nakagawa, Takao, Narita, Masanao, Noda, Manabu, Okuda, Haruyuki, Okumura, Ken'ichi, Onaka, Takashi, Roellig, Thomas L., Sato, Shinji, Shibai, Hiroshi, Smith, Beverly J., Tanabe, Toshihiko, Tanaka, Masahiro, Watabe, Toyoki, Yamamura, Issei, and Yuen, Lunming

Subjects
Physics, Infrared astronomy, Zodiacal light, Spacecraft, Infrared, Liquid helium, business.industry, media_common.quotation_subject, Infrared telescope, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, law.invention, Telescope, Space and Planetary Science, law, Sky, Astrophysics::Earth and Planetary Astrophysics, business, Astrophysics::Galaxy Astrophysics, media_common
Abstract

著者人数：28名, Accepted: 1996-09-02, 資料番号: SA1001322000

Published
1996

40. [CII] 158μm and [OI] 63μm Observations of the Galactic Center Region

Author

Low, Frank J., Mizutani, Kohei, Maihara, Toshinori, Matsuhara, Hideo, Nakagawa, Takao, Shibai, Hiroshi, Okuda, Haruyuki, Kobayashi, Yukiyasu, Hiromoto, Norihisa, and Nishimura, Tetsuo

Abstract

Note: Submitted to Part 1 of the Astrophysical Journal on April 7, 1991, 資料番号: SA8000408000

Published
1991

41. Large-Scale [CII] 158 Micron Emission of the Galaxy

Author

Low, Frank J., Shibai, Hiroshi, Okuda, Haruyuki, Nakagawa, Takao, Matsuhara, Hideo, Maihara, Toshinori, Mizutani, Kohei, Kobayashi, Yukiyasu, Hiromoto, Norihisa, and Nishimura, Tetsuo

Abstract

Note: Accepted for publication in Part 1 of the Astrophysical Journal on December 7, 1990, 資料番号: SA8000429000

Published
1990

42. Far-Infrared Spectroscopic Observations of Photodissociation Regions

Author

NAKAGAWA, Takao, OKUDA, Haruyuki, SHIBAI, Hiroshi, MATSUHARA, Hideo, MAIHARA, Toshinori, MIZUTANI, Kohei, Low, F. J., NISHIMURA, Tetsuo, KOBAYASHI, Yukiyasu, and HIROMOTO, Norihisa

Abstract

遠紫外線(波長912A∿2000A)が支配的な加熱源であり, そのために物理・化学状態が遠紫外線量によって決定されている星間領域を, 光解離領域と呼ぶ。この領域は, 電離領域から分子雲にかけてのエネルギーの流れを司どるとともに, 分子雲の化学状態に大きな影響を与えている。しかし, このように重要な領域でありながら, 広範囲な観測は従来はなされていなかった。我々は, 口径50cmの気球搭載赤外線望遠鏡および超流動液体ヘリウム冷却ファブリ・ペロー分光器を用いて, 銀河系内の様々な光解離領域について, 遠赤外スペクトル線分光観測を行った。目的のスペクトル線は, 光解離領域で最も明るい二本の微細構造線 : [CII](波長158μm)および[OI](波長63μm)である。特に[CII]スペクトル線については, 従来の空間チョッピング方式に加えて, 周波数スイッチング方式を採用し, 空間的に広がった[CII]スペクトル線を, 世界で初めて直接的に観測することに成功した。主な観測対象は, M17・NGC6334等の活発な星生成領域, 我々の銀河の中心領域, そして銀河面の広範囲のマッピング観測など, 広範囲にわたる。この観測により, 光解離領域の物理・化学状態の理解が進んだ。特に, 光解離領域が空間的に大きく広がり, かつ星間ガスの中の大きな質量を占めていることが明らかになった。, Interstellar far-ultraviolet radiation (FUV : 912-^2P_. 158μm) and [OI] (^3P_1-^3P_2,63μm), both of which are the most important coolants in photodissociation regions. We have observed many kinds of photodissociation regions, including active star-forming regions (M17 and NGC6334), central regions of our Galaxy, and wide regions along the Galactic plane. Our observations showed that (1) photodissociation regions are very clumpy and that FUV penetrates deep into clouds, (2) photodissociation regions are ubiquitous, and (3) photodissociation regions are not minor interstellar components but their total mass in our Galaxy amounts to 40% of that of molecular gas., 資料番号: SA0166942000

Published
1990

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