Naoto Kobayashi

The University of Tokyo

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Chikako Yasui

National Astronomical Observatory of Japan

100

A. T. Tokunaga

University of Hawaii–West Oahu

Hiroshi Terada

National Astronomical Observatory of Japan

Yuji Ikeda

Kyoto Sangyo University

Sohei Kondo

The University of Tokyo

Noriyuki Matsunaga

The University of Tokyo

Masanori Iye

National Astronomical Observatory of Japan

Hideyo Kawakita

Kyoto Sangyo University

Miwa Goto

University of Yamanashi

Satoshi Hamano

National Astronomical Observatory of Japan

Cooperative Institutions

The University of Tokyo

531

National Astronomical Observatory of Japan

Kyoto University

Osaka University

Tohoku University

Centre National de la Recherche Scientifique

176

Nagoya University

170

Hokkaido University

156

University of the Basque Country

150

Tokyo University of Science

140

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Fabrication and current optical performance of a large diamond-machined ZnSe immersion grating

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2010)

Yuji Ikeda Naoto Kobayashi Paul J. Kuzmenko Steve L. Little Chikako Yasui

ZnSe immersion gratings provide the possibility of high resolution spectroscopy in the wide infrared wavelength region from the NIR (Near Infrared) to the MIR (Mid Infrared), because ZnSe has a high refractive index (n ~ 2.45) and a low internal extinction in these wavelength regions. We are developing ZnSe immersion grating for a ground-based NIR high-resolution spectrograph and a space MIR high-resolution spectrograph. We already have produced fine grooves on the ZnSe flat substrate with a small pitch (~ 30 μm) using nano precision flycutting technique at the Lawrence Livermore National Laboratory,1 which satisfies our requirements even for the short NIR application.² Our next step is to fabricate a large prism-shaped ZnSe immersion grating with this technology. The triangle prism has the entrance surface 50mm × 23mm and the apex angle of 70 deg. Untile now, we tried three R&D cutting runs. We examined the optical performances of the immersion grating sample from the second cutting run, which showed the best performances. Although a lot of chipping are seen at the edge of the blaze by the microscopic observation, we found that the groove shape is quite good with the surface irregularity of 0.74λ (pv) and the random pitch error of 5.2 nm (rms), which closely meet with our requirements. In the HeNe laser spectra taken under both grism and immersion configurations, strong ghosts were observed at the intermedium of the diffracted orders. These interorder ghosts may originate from the differences of the pitch and/or shape between odd and even grooves due to the cutting procedures. In addition, we also investigated a suitable reflectivecoating for the diffraction surface. As a result, we concluded that aluminum or cupper by suppering process is the best materials in the wavelength region of WINERED. Finally, we discuss the pssible improvement points and prospect for the next trial in this summer.

Immersion

10.1117/12.856631

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Citations (14)

Potentially Modulated GaAs/GaNAs/InGaAs Quantum Wells for Solar Cell Applications

MRS Proceedings (2005)

Naoto Kobayashi Naoyuki Sasaki Yoshitaka Okada

10.1557/proc-0891-ee10-33

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Citations (1)

Chronological changes in prosaposin in the developing rat brain

Neuroscience Research (2011)

Bing Xue Jie Chen Huiling Gao Shouichiro Saito Naoto Kobayashi

10.1016/j.neures.2011.06.001

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Citations (7)

Mid-infrared camera and spectrometer on board SPICA

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2012)

Hirokazu Kataza Takehiko Wada Itsuki Sakon Naoto Kobayashi Yuki Sarugaku

SPICA (Space Infrared Telescope for Cosmology and Astrophysics) is an astronomical mission optimized for mid- and far-infrared astronomy, envisioned for launch in early 2020s. The core wavelength coverage of this mission is 5 to 200 micron. Mid-infrared Camera and Spectrometer (MCS) will provide imaging and spectroscopic observing capabilities in the mid-infrared region with 4 modules. WFC (Wide Field Camera) has two 5 arcminutes square field of view and covers the wavelength range from 5 to 38 micron. MRS (Mid Resolution Spectrometer) has integral field units by image slicer and covers the wavelength range from 12.2 to 37.5 micron simultaneously using dichroic filter and two sets of spectrometers. HRS (High Resolution Spectrometer) covers the wavelength range from 12 to 18 micron with resolving power 20000 to 30000, and it has optional short wavelength channel which covers from 4 to 8 micron with resolving power 30000. LRS (Low Resolution Spectrometer) adopts prism disperser and covers the wavelength range from 5 to 38 micron with resolving power 50 to 100. Here, we present detailed specifications of MCS, optical design, and estimated performance on orbit.

Spica

Imaging spectrometer

Prism

Field of view

Spectral resolution

10.1117/12.926082

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Citations (16)

Astrophysical calibration of the oscillator strengths of YJ-band absorption lines in classical Cepheids

arXiv (Cornell University) (2023)

S. S. Elgueta Noriyuki Matsunaga Mingjie Jian Daisuke Taniguchi Naoto Kobayashi

Newly-developed spectrographs with increased resolving powers, particularly those covering the near-IR range, allow the characterization of more and more absorption lines in stellar spectra. This includes the identification and confirmation of absorption lines and the calibration of oscillator strengths. In this study, we provide empirical values of loggf based on abundances of classical Cepheids obtained with optical spectra in Luck (2018), in order to establish the consistency between optical and infrared abundance results. Using time-series spectra of classical Cepheids obtained with WINERED spectrograph (0.97-1.35 $\mu$ m, R ~28000, we demonstrate that we can determine the stellar parameters of the observed Cepheids, including effective temperature (Teff), surface gravity (logg), microturbulence, and metallicity. With the newly calibrated relations of line-depth ratios (LDRs), we can achieve accuracy and precision comparable to optical studies (Luck 2018), with uncertainties of 90K and 0.108 dex for Teff, and log g, respectively. Finally, we created a new atlas of absorption lines, featuring precise abundance measurements of various elements found in the atmosphere of Cepheids (including neutron-capture elements), with loggf values that have been astrophysically calibrated.

Surface gravity

Microturbulence

Effective temperature

10.48550/arxiv.2307.00158

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Citations (0)

Classical Cepheids and RR Lyrae stars: similar, but not too much.

Memorie della Societa Astronomica Italiana (2016)

G. Bono V. F. Braga A. Pietrinferni Davide Magurno M. Dall’Ora

RR Lyrae variable

Instability strip

Variable star

Source

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Synthesis of superparamagnetic Co–Pt nanoparticle in Pyrococcus furiosus virus-like particle crystal

Journal of Physics and Chemistry of Solids (2022)

Makoto Taniguchi Akifumi Higashiura Naoto Kobayashi Daisuke Kanda Kakeru Tagata

Superparamagnetism

Pyrococcus furiosus

Crystal (programming language)

10.1016/j.jpcs.2022.110840

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Citations (2)

Walsh Function Based Position Sensorless Control for Interior Permanent Magnet Motor Drives using Ripple-Current of High-Frequency Triangular-Wave-Carried PWM Inverter

IEEJ Transactions on Industry Applications (2002)

Krit Choeisai Naoto Kobayashi Seiji Kondo

This paper proposes the Walsh function based position sensorless drive method of a PM motor by using high-frequency 20[kHz] triangular-wave-carrier PWM inverter ripple-current. The proposed method uses the Walsh harmonic of PWM inverter ripple-current to estimate the motor rotor position. By using the high frequency switching ripple-current, the period of the rotor position estimation has been decreased and improves the step response of PM motor. The Walsh function makes it possible to use a definite-integrator as the Walsh harmonic detector that can separate the small ripple-current signal from the motor drive-current signal. The Walsh harmonic detector circuit consists of less parts than that of the Fourier harmonic detector circuit. The validity of the proposed method was clarified by several experimental results.

Harmonic

Torque ripple

10.1541/ieejias.122.830

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Citations (1)

Formation of research strategy and synthetic research evaluation based on the strategy

Synthesiology (2011)

Naoto Kobayashi Osamu Nakamura Kenta Ooi

この論文では研究戦略の形成とそれに基づく構成的な研究評価について考察した。特に研究遂行にあたっては、戦略形成の一環として研究プログラムの目標とそれを達成するためのシナリオの設定が大切であることを強調し、その研究戦略に沿った研究評価を行うことの重要性を指摘した。また研究評価にあたっては、研究の進展（progress）、深さ（depth）、位相（phase）の3側面から評価を行うとともに、それらを研究戦略と対比しつつ演繹・帰納・仮説形成（アブダクション）用語1による推論を組みあわせて構成することの重要性や、最終的に総合的な評価を形成する際にも構成的な評価法が重要なことを述べた。さらに産総研における研究ユニット評価および長崎県における公的研究機関の研究プログラム形成と評価の実情を紹介して、構成的な評価法との対比を試みた。構成的な評価法は、研究の価値を引き出し、次の進化に向けるために必要な創造的営みの一つとして捉えることができる。

10.5571/synth.4.11

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Citations (1)

A Survey of Near-infrared Diffuse Interstellar Bands

Bulletin de la Société Royale des Sciences de Liège (2018)

Satoshi Hamano Naoto Kobayashi Hideyo Kawakita Yuji Ikeda Sohei Kondo

We propose a study of interstellar molecules with near-infrared (NIR) high-resolution spectroscopy as a science case for the 3.6-m Devasthal Optical Telescope (DOT). In particular, we present the results obtained on-going survey of diffuse interstellar bands (DIBs) in NIR with the newly developed NIR high-resolution spectrograph WINERED, which offers a high sensitivity in the wavelength range of 0.91-1.36 µm. Using the WINERED spectrograph attached to the 1.3-m Araki telescope in Japan, we obtained high-quality spectra of a number of early-type stars in various environments, such as diffuse interstellar clouds, dark clouds and star-forming regions, to investigate the properties of NIR DIBs and constrain their carriers. As a result, we successfully identified about 50 new NIR DIBs, where only five fairly strong DIBs had been identified previously. Also, some properties of DIBs in the NIR are discussed to constrain the carriers of DIBs.

Spectral resolution

10.25518/0037-9565.7702

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Citations (1)