Prof. Masao Saito Profile

Prof. Masao Saito

at National Astronomical Observatory of Japan

SPIE Involvement:

Author

Proceedings Article | 29 August 2022 Presentation + Paper

Seismic isolation system design and performance of TMT telescope structure

Masahiro Sugimoto, Atsushi Kato, Junji Takaki, Masaki Tabata, Tomoya Hattori, Amir Sadjadpour, Brady Espeland, Hugh Thompson, Satoru Sofuku, Yutaka Ezaki, Noboru Kawaguchi, Tomonori Usuda, Hiroshi Kusumoto, Masao Saito, Hiroshi Terada, Seiichi Tazawa, Kyle Kinoshita

Proceedings Volume 12182, 1218216 (2022) https://doi.org/10.1117/12.2631409

KEYWORDS: Telescopes, Earthquakes, Finite element methods, Observatories, Prototyping, Thirty Meter Telescope, Astronomy

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Proceedings Article | 13 December 2020 Presentation + Paper

High precision machining in TMT (Thirty Meter Telescope) structure manufacturing

Kenji Kamikawa, Akihiro Nagai, Takuya Ashida, Kazuhiko Tani, Tatsuya Nariyama, Takayuki Ishida, Junji Takaki, Noboru Kawaguchi, Makoto Endo, Yutaka Ezaki, Tomonori Usuda, Masao Saito

Proceedings Volume 11445, 114451R (2020) https://doi.org/10.1117/12.2560614

KEYWORDS: Thirty Meter Telescope, Manufacturing, Temperature metrology, Surface finishing, Large telescopes, Surface roughness, Abrasives

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Proceedings Article | 27 July 2016 Paper

Large aperture millimeter/submillimeter telescope: which is more cost-effective, aperture synthesis telescope versus large single dish telescope?

Satoru Iguchi, Masao Saito

Proceedings Volume 9906, 99062T (2016) https://doi.org/10.1117/12.2232022

KEYWORDS: Telescopes, Antennas, Synthetic apertures, Optical instrument design, Receivers, Optical correlators, Analog electronics, Spectroscopy, Cryogenics, Chemical mechanical planarization

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Proceedings Article | 19 July 2016 Paper

Development of the new multi-beam 100 GHz band SIS receiver FOREST for the Nobeyama 45-m Telescope

Tetsuhiro Minamidani, Atsushi Nishimura, Yusuke Miyamoto, Hiroyuki Kaneko, Hiroyuki Iwashita, Chieko Miyazawa, Hiroyuki Nishitani, Takuya Wada, Yasunori Fujii, Toshikazu Takahashi, Yoshizo Iizuka, Hideo Ogawa, Kimihiro Kimura, Yuto Kozuki, Yutaka Hasegawa, Mitsuhiro Matsuo, Shinji Fujita, Satoshi Ohashi, Kana Morokuma-Matsui, Jun Maekawa, Kazuyuki Muraoka, Taku Nakajima, Tomofumi Umemoto, Kazuo Sorai, Fumitaka Nakamura, Nario Kuno, Masao Saito

Proceedings Volume 9914, 99141Z (2016) https://doi.org/10.1117/12.2232137

KEYWORDS: Receivers, Telescopes, Astronomical telescopes, Observatories, Signal processing, Galactic astronomy, Astronomy, Mirrors, Space telescopes, Polarization

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Proceedings Article | 6 August 2014 Paper

ALMA observations during its first early science cycles

Lars-Åke Nyman, Pierre Cox, Stuartt Corder, Masao Saito, Andreas Lundgren, Baltasar Vila-Vilaro, Daniel Espada, Eric Villard, Emilio Barrios, Paola Andreani, John Hibbard, Ken'ichi Tatematsu

Proceedings Volume 9149, 91490J (2014) https://doi.org/10.1117/12.2057685

KEYWORDS: Calibration, Antennas, Observatories, Antimony, Data archive systems, Astronomy, Receivers, Software development, Data modeling, Data processing

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Proceedings Article | 22 July 2014 Paper

A holography receiver for the Atacama Large millimeter/submillimeter array antenna and the measured surface deformation

Hitoshi Kiuchi, Masumi Yamada, Masahiro Sugimoto, Masao Saito

Proceedings Volume 9145, 91454J (2014) https://doi.org/10.1117/12.2055377

KEYWORDS: Holography, Antennas, Receivers, Temperature metrology, Sun, Phase measurement, Analog electronics, Interferometers, Aluminum, Astronomy

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Proceedings Article | 22 July 2014 Paper

Development of high-accuracy pointing verification for ALMA antenna

Ayumu Matsuzawa, Masao Saito, Satoru Iguchi, Kouichiro Nakanishi, Hiro Saito

Proceedings Volume 9145, 91451Z (2014) https://doi.org/10.1117/12.2055771

KEYWORDS: Antennas, Velocity measurements, Integrated optics, Error analysis, Wind measurement, Stars, Reliability, Astronomy, Ocean optics, Radio optics

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Pointing performance of a radio telescope antenna is important in radio astronomical observations to obtain accurate intensity of a target source. The pointing errors of the ALMA ACA antenna are required to be better than 0.6 arcsec rss, which corresponds to 1/10 and 1/20 of the field of view of the ALMA ACA 12-m and 7-m antenna at 950 GHz, respectively. The pointing verification measurements of the ACA antenna were performed using an Optical pointing telescope (OPT) mounted on the antenna backup structure at the ALMA Operations Site Facility at 2900m above the sea level. Pointing errors of these OPT measurements contain three different origins; originated from antenna, originated of atmosphere (optical seeing), and originated of OPT itself. In order to estimate pointing errors of the antenna origin, we need to subtract the components of optical seeing and OPT itself accurately, while we need to add components that cannot be measured in the OPT measurements. The ACA antenna verification test report demonstrated that all the ACA 7-m antenna meets pointing specification of ALMA. However, about one-third of datasets, values of estimated optical seeing is larger than measured pointing errors. We re-examined a procedure to estimate optical seeing, by investigating the property of optical seeing from the high-sampling OPT pointing measurements of long tracking a bright star for 15 minutes. Particularly, we examined the relation between optical seeing and sampling rate derived from Kolmogorov PSD. Our analysis indicated that the optical seeing at ALMA site may have been overestimated in the verification test. We present a new relation between optical seeing and sampling rate proportional to average wind velocity during measurement. We used this new relation to derive the optical seeing and as a result the number of datasets becomes half in which the optical seeing is larger than measured pointing errors. As a result, we successfully develop a new verification method of optical seeing that has high reliability.

Proceedings Article | 27 September 2012 Paper

Photonic local oscillator technics for large-scale interferometers

H. Kiuchi, M. Saito, S. Iguchi

Proceedings Volume 8444, 84442O (2012) https://doi.org/10.1117/12.925907

KEYWORDS: Phase measurement, Signal generators, Signal detection, Phase shift keying, Signal processing, Digital filtering, Polarization, Sensors, Oscillators, Fiber Bragg gratings

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Proceedings Article | 17 September 2012 Paper

Atacama compact array antennas

M. Saito, J. Inatani, K. Nakanishi, H. Saito, S. Iguchi

Proceedings Volume 8444, 84443H (2012) https://doi.org/10.1117/12.926987

KEYWORDS: Antennas, Holography, Received signal strength, Reflectors, Error analysis, Electroluminescence, Telescopes, Stars, Fast packet switching, Metrology

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Proceedings Article | 17 September 2012 Paper

Very large millimeter/submillimeter array toward search for 2nd Earth

Satoru Iguchi, Masao Saito

Proceedings Volume 8444, 84443I (2012) https://doi.org/10.1117/12.927119

KEYWORDS: Planets, Antennas, Receivers, Spatial resolution, Stars, Astronomy, Telescopes, Radio telescopes, Atmospheric modeling, Optical instrument design

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Proceedings Article | 28 July 2010 Paper

Wind-induced pointing errors and surface deformation of a 10-m submillimeter antenna

Nobuharu Ukita, Hajime Ezawa, Sachiko Onodera, Masao Saito

Proceedings Volume 7733, 77331D (2010) https://doi.org/10.1117/12.857279

KEYWORDS: Antennas, Reflectors, Computer programming, Telescopes, Servomechanisms, Turbulence, Sensors, Motion measurement, Wind measurement, Reflector telescopes

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Proceedings Article | 27 June 2006 Paper

Elevation angle dependence of the SMA antenna focus position

Satoki Matsushita, Masao Saito, Kazushi Sakamoto, Todd Hunter, Nimesh Patel, Tirupati Sridharan, Robert Wilson

Proceedings Volume 6275, 62751W (2006) https://doi.org/10.1117/12.670642

KEYWORDS: Antennas, Shape memory alloys, Jupiter, Reflectors, Astronomy, Radio optics, Telescopes, Planets, Oscillators, Temperature metrology

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Proceedings Article | 23 June 2006 Paper

Vortex shedding from a 12-m antenna

Nobuharu Ukita, Masao Saito, Bungo Ikenoue, Jeffrey Mangum, Nicholas Emerson, Angel Otarola, Stefano Stangellini

Proceedings Volume 6267, 62673P (2006) https://doi.org/10.1117/12.670755

KEYWORDS: Antennas, Motion measurement, Turbulence, Computer programming, Reflectors, Wind measurement, Prototyping, Velocity measurements, Ultrasonics, Telescopes

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Proceedings Article | 29 September 2004 Paper

Holographic surface setting of the Sub-millimeter Array antennas

Tirupati Sridharan, Masao Saito, Nimesh Patel, Robert Christensen

Proceedings Volume 5495, (2004) https://doi.org/10.1117/12.550939

KEYWORDS: Antennas, Holography, Shape memory alloys, Near field, Astronomy, Spatial resolution, Telescopes, Receivers, Efficient operations, Optical testing

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Proceedings Article | 28 September 2004 Paper

Design and performance of the ALMA-J prototype antenna

Nobuharu Ukita, Masao Saito, Hajime Ezawa, Bungo Ikenoue, Hideharu Ishizaki, Hiroyuki Iwashita, Nobuyuki Yamaguchi, Takahiro Hayakawa

Proceedings Volume 5489, (2004) https://doi.org/10.1117/12.551523

KEYWORDS: Antennas, Computer programming, Reflectors, Holography, Observatories, Prototyping, Stars, Servomechanisms, Metrology, Telescopes

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The National Astronomical Observatory of Japan has constructed a prototype 12-m antenna of the Atacama Compact Array to evaluate its performance at the ALMA Test Facility in the NRAO VLA observatory in New Mexico, the United States. The antenna has a CFRP tube backup structure (BUS) with CFRP boards to support 205 machined Aluminum surface panels. Their accuracies were measured to be 5.9 m rms on average. A chemical treatment technique of the surface panels has successfully applied to scatter the solar radiation, which resulted in a subreflector temperature increase of about 25 degrees relative to ambient temperature during direct solar observations. Holography measurements and panel adjustments led to a final surface accuracy of 20 m rms, (weighted by 12dB edge taper), after three rounds of the panel adjustments. Based on a long term temperature monitoring of the BUS and thermal deformation FEM calculation, the BUS thermal deformation was estimated to be less than 3.1 m rms. We have employed gear drive mechanism both for a fast position switching capability and for smooth drive at low velocities. Servo errors measured with angle encoders were found to be less than 0.1 arcseconds rms at rotational velocities below 0.1 degrees s-1 and to increase to 0.7 arcseconds rms at the maximum speed of the 'on-the-fly' scan as a single dish, 0.5 deg s-1 induced by the irregularity of individual gear tooth profiles. Simultaneous measurements of the antenna motion with the angle encoders and seismic accelerometers mounted at the primary reflector mirror edges and at the subreflector showed the same amplitude and phase of oscillation, indicating that they are rigid, suggesting that it is possible to estimate where the antenna is actually pointing from the encoder readout. Continuous tracking measurements of Polaris during day and night have revealed a large pointing drift due to thermal distortion of the yoke structure. We have applied retrospective thermal corrections to tracking data for two hours, with a preliminary thermal deformation model of the yoke, and have found the tracking accuracy improved to be 0.1 - 0.3 arcseconds rms for a 15-munites period. The whole sky absolute pointing error under no wind and during night was measured to be 1.17 arcseconds rms. We need to make both an elaborated modeling of thermal deformation of the structure and systematic searches for significant correlation among pointing errors and metrology sensor outputs to achieve the stable tracking performance requested by ALMA.

Showing 5 of 15 publications

Conference Committee Involvement (2)

Modeling, Systems Engineering, and Project Management for Astronomy IX

14 December 2020 | Online Only, California, United States

Modeling, Systems Engineering, and Project Management for Astronomy VIII

10 June 2018 | Austin, Texas, United States

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