Dr. Saku Tsuneta Profile

Dr. Saku Tsuneta

at National Astronomical Observatory of Japan

SPIE Involvement:

Conference Program Committee | Author

Publications (22)

PROCEEDINGS ARTICLE | November 21, 2017

Instrument design and on-orbit performance of the solar optical telescope aboard hinode (Solar-B)

Proc. SPIE. 10566, International Conference on Space Optics — ICSO 2008

KEYWORDS: Telescopes, Mirrors, Polarization, Wavefronts, Space telescopes, Spatial resolution, Optical telescopes, Space operations, Optical instrument design, Secondary tip-tilt mirrors

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PROCEEDINGS ARTICLE | November 17, 2017

Development of compact integral field unit for spaceborne solar spectro-polarimeter

Proc. SPIE. 10563, International Conference on Space Optics — ICSO 2014

KEYWORDS: Mirrors, Spectrographs, Metals, Surface roughness, Image quality, Micromirrors, Astronomical imaging, Optics manufacturing, Cutting equipment, Iterated function systems

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A 1.5-m class aperture Solar Ultra-violet Visible and IR telescope (SUVIT) and its instruments for the Japanese next space solar mission SOLAR-C [1] are under study to obtain critical physical parameters in the lower solar atmosphere. For the precise magnetic field measurements covering field-of-view of 3 arcmin x3 acmin, a full stokes polarimetry at three magnetic sensitive lines in wavelength range of 525 nm to 1083 nm with a four-slit spectrograph of two dinesional image scanning mechanism is proposed: one is a true slit and the other three are pseudo-slits from integral field unit (IFU). To suit this configuration, besides a fiber bundle IFU, a compact mirror slicer IFU is designed and being developed.

Integral field spectroscopy (IFS), which is realized with IFU, is a two dimensional spectroscopy, providing spectra simultaneously for each spatial direction of an extended two-dimensional field. The scientific advantages of the IFS for studies of localized and transient solar surface phenomena are obvious. There are in general three methods [2][3] to realize the IFS depending on image slicing devices such as a micro-lenslet array, an optical fiber bundle and a narrow rectangular image slicer array.

So far, there exist many applications of the IFS for ground-based astronomical observations [4]. Regarding solar instrumentations, the IFS of micro-lenslet array was done by Suematsu et al. [5], the IFS of densely packed rectangular fiber bundle with thin clads was realized [6] and being developed for 4-m aperture solar telescope DKIST by Lin [7] and being considered for space solar telescope SOLAR-C by Katsukawa et al. [8], and the IFS with mirror slicer array was presented by Ren et al. [9] and under study for up-coming large-aperture solar telescope in Europe by Calcines et al. [10]

From the view point of a high efficiency spectroscopy, a wide wavelength coverage, a precision spectropolarimetry and space application, the image slicer consisting of all reflective optics is the best option among the three. However, the image slicers are presently limited either by their risk in the case of classical glass polishing techniques (see Vivès et al. [11] for recent development) or by their optical performances when constituted by metallic mirrors. For space instruments, small sized units are much advantageous and demands that width of each slicer mirror is as narrow as an optimal slit width (< 100 micron) of spectrograph which is usually hard to manufacture with glass polishing techniques. On the other hand, Canon is developing a novel technique for such as high performance gratings which can be applicable for manufacturing high optical performance metallic mirrors of small dimensions.

For the space-borne spectrograph of SUVIT to be aboard SOLAR-C, we designed the IFS made of a micro image slicer of 45 arrayed 30-micron-thick metal mirrors and a pseudo-pupil metal mirror array re-formatting three pseudo-slits; the design is feasible for optical configuration sharing a spectrograph with a conventional real slit. According to the optical deign, Canon manufactured a prototype IFU for evaluation, demonstrating high performances of micro image slicer and pupil mirrors; enough small micro roughness for visible light spectrographs, sharp edges for efficient image slices, surface figure for high image quality, etc. In the following, we describe the optical design of IFU feasible for space-borne spectrograph, manufacturing method to attain high optical performance of metal mirrors developed by Canon, and resulted performance of prototype IFU in detail.

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PROCEEDINGS ARTICLE | July 28, 2014

Development of micro image slicer of integral field unit for spaceborne solar spectrograph

Proc. SPIE. 9151, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation

KEYWORDS: Mirrors, Spectrographs, Optical design, Metals, Surface roughness, Image quality, Micromirrors, Optics manufacturing, Prototyping, Iterated function systems

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PROCEEDINGS ARTICLE | September 21, 2012

WISH for deep and wide NIR surveys

Proc. SPIE. 8442, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave

KEYWORDS: Near infrared, Telescopes, Optical filters, Mirrors, Astronomy, Stars, Satellites, Ultraviolet radiation, Space telescopes, Galactic astronomy

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PROCEEDINGS ARTICLE | September 17, 2012

Chromospheric Lyman-alpha spectro-polarimeter (CLASP)

Proc. SPIE. 8443, Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray

KEYWORDS: Mirrors, Spectrographs, Visible radiation, Polarization, Scattering, Cameras, Coating, Magnetism, Wave plates, Solar processes

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PROCEEDINGS ARTICLE | September 17, 2012

The x-ray/EUV telescope for the Solar-C mission: science and development activities

Proc. SPIE. 8443, Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray

KEYWORDS: Telescopes, Mirrors, X-rays, Magnetism, Coronagraphy, Space telescopes, Spatial resolution, X-ray imaging, X-ray telescopes, Plasma

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PROCEEDINGS ARTICLE | November 10, 2011

Modeling and verification of the diffraction-limited visible light telescope aboard the solar observing satellite HINODE

Proc. SPIE. 8336, Integrated Modeling of Complex Optomechanical Systems

KEYWORDS: Thermography, Telescopes, Mirrors, Visible radiation, Space telescopes, Optical telescopes, Space operations, Performance modeling, Thermal modeling, Temperature metrology

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PROCEEDINGS ARTICLE | October 7, 2011

Ly-alpha polarimeter design for CLASP rocket experiment

Proc. SPIE. 8148, Solar Physics and Space Weather Instrumentation IV

KEYWORDS: Refractive index, Beam splitters, Magnesium fluoride, Modulation, Polarization, Ultraviolet radiation, Wave plates, Polarimetry, Transmittance, Prototyping

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A sounding-rocket program called the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is proposed to be launched in the summer of 2014. CLASP will observe the solar chromosphere in Ly-alpha (121.567 nm), aiming to detect the linear polarization signal produced by scattering processes and the Hanle effect for the first time. The polarimeter of CLASP consists of a rotating half-waveplate, a beam splitter, and a polarization analyzer. Magnesium Fluoride (MgF2) is used for these optical components, because MgF2 exhibits birefringent property and high transparency at ultraviolet wavelength. The development and comprehensive testing program of the optical components of the polarimeter is underway using the synchrotron beamline at the Ultraviolet Synchrotron Orbital Radiation Facility (UVSOR). The first objective is deriving the optical constants of MgF2 by the measurement of the reflectance and transmittance against oblique incident angles for the s-polarized and the p-polarized light. The ordinary refractive index and extinction coefficient along the ordinary and extraordinary axes are derived with a least-square fitting in such a way that the reflectance and transmittance satisfy the Kramers-Krönig relation. The reflection at the Brewster's Angle of MgF2 plate is confirmed to become a good polarization analyzer at Ly-alpha. The second objective is the retardation measurement of a zeroth-order waveplate made of MgF2. The retardation of a waveplate is determined by observing the modulation amplitude that comes out of a waveplate and a polarization analyzer. We tested a waveplate with the thickness difference of 14.57 um. The 14.57 um waveplate worked as a half-waveplate at 121.74 nm. We derived that a waveplate with the thickness difference of 15.71 um will work as a half-waveplate at Ly-alpha wavelength. We developed a prototype of CLASP polarimeter using the MgF2 half-waveplate and polarization analyzers, and succeeded in obtaining the modulation patterns that are consistent with the theoretical prediction. We confirm that the performance of the prototype is optimized for measuring linear polarization signal with the least effect of the crosstalk from the circular polarization.

PROCEEDINGS ARTICLE | October 6, 2011

The SOLAR-C mission: current status

Proc. SPIE. 8148, Solar Physics and Space Weather Instrumentation IV

KEYWORDS: Telescopes, Solar energy, Sun, Spectroscopy, Magnetism, Coronagraphy, Space telescopes, Wind energy, Extreme ultraviolet, Solar processes

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PROCEEDINGS ARTICLE | October 6, 2011

Photon-counting soft x-ray telescope for the Solar-C mission

Proc. SPIE. 8148, Solar Physics and Space Weather Instrumentation IV

KEYWORDS: Telescopes, Mirrors, Sensors, Photons, X-rays, Plasmas, Magnetism, Coronagraphy, Space telescopes, X-ray telescopes

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PROCEEDINGS ARTICLE | October 6, 2011

Overview of Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP)

Proc. SPIE. 8148, Solar Physics and Space Weather Instrumentation IV

KEYWORDS: Telescopes, Mirrors, Spectrographs, Rockets, Magnesium fluoride, Polarization, Scattering, Magnetism, Wave plates, Solar processes

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PROCEEDINGS ARTICLE | August 6, 2010

WISH: wide-field imaging surveyor at high redshift

Proc. SPIE. 7731, Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave

KEYWORDS: Staring arrays, Near infrared, Telescopes, Optical filters, Mirrors, Sensors, Ultraviolet radiation, Space telescopes, Galactic astronomy, James Webb Space Telescope

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PROCEEDINGS ARTICLE | October 12, 2004

Focal plane CCD camera for the X-Ray Telescope (XRT) aboard SOLAR-B

Proc. SPIE. 5487, Optical, Infrared, and Millimeter Space Telescopes

KEYWORDS: Telescopes, Electronics, Cameras, X-rays, Quantum efficiency, Plasmas, Magnetism, CCD cameras, Charge-coupled devices, X-ray telescopes

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PROCEEDINGS ARTICLE | October 12, 2004

Development of ultra-light-weight mirror with carbon/carbon composites for optical-IR astronomy

Proc. SPIE. 5487, Optical, Infrared, and Millimeter Space Telescopes

KEYWORDS: Carbon, Mirrors, Astronomy, Polishing, Composites, Photography, Plating, Spherical lenses, Electroless plating, Surface finishing

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PROCEEDINGS ARTICLE | October 12, 2004

The Solar Optical Telescope onboard the Solar-B

Proc. SPIE. 5487, Optical, Infrared, and Millimeter Space Telescopes

KEYWORDS: Optical components, Telescopes, Mirrors, Polarization, Coating, Wavefronts, Space telescopes, Optical telescopes, Space operations, Temperature metrology

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PROCEEDINGS ARTICLE | October 12, 2004

Image stabilization system on SOLAR-B Solar Optical Telescope

Proc. SPIE. 5487, Optical, Infrared, and Millimeter Space Telescopes

KEYWORDS: Telescopes, Mirrors, Electronics, Ferroelectric materials, Sun, Control systems, CCD cameras, Space telescopes, Servomechanisms, Optical telescopes

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PROCEEDINGS ARTICLE | March 11, 2003

Balloon-borne hard x-ray spectrometer for flare observations

Proc. SPIE. 4851, X-Ray and Gamma-Ray Telescopes and Instruments for Astronomy

KEYWORDS: Electronics, Solar energy, Sun, Sensors, Spectroscopy, Signal processing, X-ray telescopes, Hard x-rays, Solar processes, Lead

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PROCEEDINGS ARTICLE | August 28, 1998

Development of the tip-tilt mirror system for the solar XUV telescope

Proc. SPIE. 3356, Space Telescopes and Instruments V

KEYWORDS: Actuators, Telescopes, Mirrors, Rockets, Sun, Control systems, Space telescopes, Extreme ultraviolet, Control systems design, Content addressable memory

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PROCEEDINGS ARTICLE | July 11, 1997

Development of multilayer mirrors for the XUV Doppler telescope

Proc. SPIE. 3113, Grazing Incidence and Multilayer X-Ray Optical Systems

KEYWORDS: Telescopes, Mirrors, Multilayers, Doppler effect, Silicon, Reflectivity, Space telescopes, Photomasks, Extreme ultraviolet, Plasma

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PROCEEDINGS ARTICLE | July 11, 1997

XUV Doppler telescope with multilayer optics

Proc. SPIE. 3113, Grazing Incidence and Multilayer X-Ray Optical Systems

KEYWORDS: Telescopes, Mirrors, Rockets, Iron, Doppler effect, Reflectivity, Space telescopes, Extreme ultraviolet, Charge-coupled devices, X-ray telescopes

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PROCEEDINGS ARTICLE | November 25, 1996

Japanese sounding rocket experiment with the solar XUV Doppler telescope

Proc. SPIE. 2804, Missions to the Sun

KEYWORDS: Telescopes, Mirrors, Rockets, Multilayers, Doppler effect, Coronagraphy, Space telescopes, Extreme ultraviolet, Charge-coupled devices, Solar processes

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PROCEEDINGS ARTICLE | November 25, 1996

New high-thermal-conductivity composite material for high-precision space optics

Proc. SPIE. 2804, Missions to the Sun

KEYWORDS: Optical fibers, Mirrors, Curium, Glasses, Composites, Astronomical imaging, Optical telescopes, Thermal modeling, Temperature metrology, Absorption

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Showing 5 of 22 publications

Conference Committee Involvement (1)

Optical, Infrared, and Millimeter Space Telescopes

21 June 2004 | Glasgow, United Kingdom

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