Susumu Kuwamura

Hokkaido University

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Naoshi Baba

Ibaraki University

Noriaki Miura

Kitami Institute of Technology

S. Ueno

Ryukoku University

Kiyoshi Ichimoto

Kyoto University

Yuji Norimoto

National Astronomical Observatory of Japan

Yoshikazu Nakatani

Kyoto University

Yoichiro Hanaoka

National Astronomical Observatory of Japan

S. Nagata

Kyoto University

Reizaburou Kitai

Kyoto University

Hideki Takami

Nagoya University

Cooperative Institutions

Kitami Institute of Technology

National Astronomical Observatory of Japan

Kyoto University

The University of Tokyo

Japan Aerospace Exploration Agency

Hokkaido University

Astronomical Observatory

The Graduate University for Advanced Studies, SOKENDAI

Institute of Space and Astronautical Science

Subaru (Japan)

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Stellar Speckle Spectroscopy for High Spatial Resolution and its Observational Data Analysis

Susumu Kuwamura

Speckle imaging

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Citations (0)

Wavelength scanning profilometry for real-time surface shape measurement

Applied Optics (1997)

Susumu Kuwamura Ichirou Yamaguchi

Wavelength scanning profilometry suitable for real-time surface shape measurement is proposed. A phase slope of the interference signal generated by a wavelength scan is measured at an individual image pixel on-line. The parallel outputs of these on-line measurements show a map of surface height in real time. Experiments where a tunable dye laser was used were conducted to simulate the real-time measurements of step objects with specular and diffuse surfaces. The results have shown that a height map is available at any moment during the wavelength scan, and the measurement accuracy of height increases as the scanning proceeds. For a scanning width of 25 nm, the accuracy was as high as 1 mum. Analyses of the measurement accuracy are given.

10.1364/ao.36.004473

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Citations (131)

Wavelet Denoising for Tomographically Reconstructed Image

Optical Review (2006)

Susumu Kuwamura

Smoothing

10.1007/s10043-006-0129-z

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Citations (6)

Toward high-resolution imaging with a simple adaptive-optics system

Optics Letters (1996)

Naoshi Baba Susumu Kuwamura Noriaki Miura Yuji Norimoto

High-resolution imaging with reference to a widely separated star is examined. Peak tracking of the specklegram in the reference channel results in a high-resolution image in the observational channel. A binary star with angular separation of 30.5 arcsec is examined in white light, and the resultant image of the primary star obtained with reference to the secondary star is shown to have better resolution than the centroid tracking image by a factor of 3.

Centroid

Star (game theory)

Tracking (education)

Point spread function

10.1364/ol.21.000626

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Citations (4)

Stellar spectra reconstruction from speckle spectroscopic data

The Astronomical Journal (1993)

Susumu Kuwamura Naoshi Baba Noriaki Miura E. K. Hege

We describe a method to reconstruct stellar spectra from dispersed speckle data with diffraction-limited angular resolution. A shift-and-add (SAA) method is applied on many short exposure frames, each of which contains a dispersed speckle image and a corresponding nondispersed speckle image as a reference. The spectra of the binary star ADS 16836 were reconstructed in wideband and low dispersion mode from the data taken with the Hokudai speckle spectroscopic camera system using the Okayama 188 cm telescope. The result shows the well-separated spectra of the primary and the secondary stars, which are otherwise too close to be distinguishable due to atmospheric turbulence. These results also demonstrate high spatial resolution spectroscopy for a binary star and for a resolvable hypergiant using our SAA speckle method.

Speckle imaging

10.1086/116465

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Citations (12)

Experiments of GLAO using the domeless solar telescope of the Hida Observatory

Adaptive Optics Systems VI (2018)

Noriaki Miura Takahiro Suzuki Shinya Takahashi Susumu Kuwamura Naoshi Baba

We report experiments of solar ground-layer (GL) adaptive optics (AO) using the 60cm domeless solar telescope of the Hida Observatory, Japan. We developed an averaging-type GL wavefront sensor and confirmed that it properly worked in computer simulations. We set the wavefront sensor behind a conventional AO system and modified AO software so as to drive a deformable mirror using the GL sensor. We conducted solar observations with the GLAO system in September, 2017. It worked to improve observational images over wide fields.

Wavefront sensor

Solar telescope

Solar observatory

Secondary mirror

10.1117/12.2311985

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Citations (2)

Speckle decorrelation in surface profilometry by wavelength scanning interferometry

Applied Optics (1998)

Ichirou Yamaguchi Akihiro Yamamoto Susumu Kuwamura

The accuracy and the measurement range of surface profilometry by wavelength scanning interferometry applied to diffusely reflecting surfaces are investigated. The influences of surface roughness and the imaging system in the interferometer are theoretically analyzed by derivation of the autocorrelation function of interferograms arising from wavelength scanning. By using a dye laser with a tuning range of 4.2 nm to a yield resolution of 39.1 μm, we have observed interferograms and their Fourier transforms and autocorrelations to study effects of defocusing and the size ratio of speckle to the CCD pixel for a plane diffuse object positioned normal to the incident beam.

Speckle imaging

Decorrelation

10.1364/ao.37.006721

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Citations (35)

Application of solar SCIDAR technique to measuring wind velocity

Imaging and Applied Optics (2013)

Noriaki Miura Ayumu Oh-ishi Susumu Kuwamura Naoshi Baba S. Ueno

We extend our solar SCIDAR technique to measuring wind velocities on turbulent layers. We apply our technique to data observed with the 60 cm domeless solar telescope at the Hida Observatory in Japan, and confirm that notable peaks corresponding to wind flows appear on a temporal-correlation plane.

Solar observatory

Solar telescope

10.1364/aopt.2013.jtu4a.6

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Deconvolution of partially compensated solar images from additional wavefront sensing

Applied Optics (2016)

Noriaki Miura Akira Oh-ishi Susumu Kuwamura Naoshi Baba S. Ueno

A technique for restoring solar images partially compensated with adaptive optics is developed. An additional wavefront sensor is installed in an adaptive optics system to acquire residual wavefront information simultaneously to a solar image. A point spread function is derived from the wavefront information and used to deconvolve the solar image. Successful image restorations are demonstrated when the estimated point spread functions have relatively high Strehl ratios.

Strehl ratio

Point spread function

Wavefront sensor

Deformable Mirror

10.1364/ao.55.002484

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Citations (3)

Shift-and-Add Method with Optically Pre-Processed Stellar Specklegrams

Optical Review (1996)

Susumu Kuwamura Ichirou Yamaguchi

Point spread function

Kernel (algebra)