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An adaptive optics (AO) system is developed for the 60cm domeless solar telescope of the Hida Observatory, Japan. Its performances are analyzed by the computer simulations, and improved by replacing the Zernike polynomials by Karhunen-Loeve functions. Also, a tomographic wavefront sensor is developed for a ground-layer AO system. From test data acquired at the Hida observatory, wavefront-phase maps both in the ground-layer and in an upper layer are successfully derived.

We are developing a new adaptive optics (AO) system for the 60cm domeless solar telescope of the Hida Observatory, Japan. The system has a deformable mirror with 97 piezo-actuators, a Shack-Hartmann wavefront sensor with a 10×10-microlens array and standard personal computers. We conducted solar observations in September, 2013, and confirmed that our AO system cancelled image-shifts so that the deviations were within the resolution of the telescope. We report the detailed performances of our new AO system.

We developed a polarimeter for the ground-based solar observation using a high-speed rotating waveplate (typically 12.5–25 revolutions s −1 ) and a high-speed camera (typically 200–400 frames s −1 ) with commercially available devices. Fast polarization modulation is required for the ground-based solar polarimetry to avoid producing seeing-induced false polarization signals. Modulation with a high-speed rotating waveplate realizes not only fast full-Stokes modulation but also wide coverage of the wavelength range, and therefore, a polarimeter with a highspeed rotating waveplate is most suitable for the simultaneous polarimetry observations at multi-wavelengths with a spectrograph. A comprehensive description of the instrument and some results of the solar spectropolarimetry with this polarimeter are given in this paper.

Solar adaptive optics (AO) systems are developed at the 60cm domeless solar telescope in the Hida Observatory, Japan. An AO system currently used has a deformable mirror with high-speed 97 electromagnetic actuators and a Shack- Hartmann wavefront sensor with a 10x10-microlens array and 4000fps-CMOS camera. Its control frequency is about 1100-1400 Hz, and hence the -3dB cutoff frequency of the system is theoretically above 100 Hz. In parallel to developing the system, a new full-scaled AO system is designed to be applicable to various observations, such as highdispersion spectroscopy and simultaneous wide-range spectroscopy. The new system will work as classical AO at first. The details of the current system, observational results using it, and the design of the new AO system are described. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

A solar adaptive optics system for a high-dispersion spectrograph is developed at the 60 cm domeless solar telescope of the Hida Observatory in Japan. Details of its optical setup are described for implementing a scanning slit spectroscopy with wavefront correction. A wavefront sensor used in the system is specified and a technique of reducing computational cost in wavefront sensing is also described. In solar observations, the improvement of contrast in images obtained with the adaptive optics system was demonstrated when a sunspot was used as a target of wavefront sensing.

A solar adaptive optics system for the 60 cm domeless solar telescope of the Hida Observatory in Japan is developed. A high-speed deformable mirror with 52 electromagnetic actuators is newly used in an experimental adaptive optics system. The use of the mirror resulted in the improvement of Strehl ratios in laboratory experiments. In solar observations, the system worked well when solar granulation was used as a target for wavefront sensing. An adaptive optics system being developed for a vertical spectrograph of the domeless solar telescope is described.

A solar adaptive optics system is developed for the 60 cm domeless solar telescope of the Hida Observatory in Japan. It is designed for compensating low order turbulence in G-ba nd using a 52-electromagnetic-act uator deformable mirror, a 6x6 Shack-Hartmann wavefront sensor and standard personal computers. The details of the system, particularly features of the deformable mirror are described. Laboratory experiments show that the use of adaptive optics raises the Strehl ratio by a factor of five for turbulence of under 99Hz. In solar observations, the improvement of resolution in long-exposure images with the adap tive optics system is demonstrated. Keywords: Adaptive optics, Solar observation 1. INTRODUCTION Adaptive optics (AO) is an indispensable tool that allows high resolution observation of the Sun using existing ground-based telescopes. Recently, several solar AO systems have been developed at major solar observatories 1 , and further multi-conjugate solar AO systems are being developed

Multi-Wavelength,High-Sp eedVideoSp ectroheliographYoichiro HanaokaNationalAstronomical Observatory ofJapan,2-21-1Osawa, Mitaka, Tokyo181-8588, JapanABSTRACTA high-sp eed video sp ectroheliograph was develop ed for imaging sp ectroscopy observations in multi-wavelengthbands.Itisattachedtothefo calplaneofsp ectrograph60cmDomelessSolarTelescop eatHidaObservatory,Kyoto University.Althoughto take sp ectroheliograms needs some timeto scan the solar imageontheslit,asp ectroheliographgetssp ectralinformationco-temp orallywithoutsu eringimageblurringsbythe seeinge ect.Therefore,asp ectroheliographis suitabletoobtaindatacub e(spatial2-D +sp ectral 1-D)forquantitativesp ectralanalysessuchasvelo city eldcalculations.Inoursp ectroheliographsystem,uptothreeCCDvideocamerascanbeattached tothesp ectrograph,andwecansimultaneously observeupthree wavelength bands, for example, Ca I I K/G-band/H,with three CCD video cameras, owing to the widewavelength coerage of the sp ectrograph.Therefore, heliograms at di erentheights in the solar atmosphere canb e obtained simultaneously.Images from the cameras are digitized by a frame grabb er to 512 (4.30along theslit) pixels256 (along the disp ersion, typically 24 A wide) lines and pro cessed by a PC with a frame rate of30 frames s1.Therefore, it takes only 17 s to obtain a set of 512512 pixel heliograms, whichcover the eldof view of 4.304.3.Keywords:sp ectroheliograph, imaging sp ectroscopy,multi-wavelength-bands1. INTRODUCTIONTostudythedynamicsofsolarphotosphereandchromosphere,itisessentiallyimp ortanttoobtainadatacub e (spatiallytwo dimensions+ sp ectrallyonedimension).Generally,toobtain adata cub e withtwo-dimensional detector suchasa CCD needs multiple exp osures, but suchatyp e of data acquisition su ersimage motions b etween subsequent exp osures due to the seeing e ect.The b est wayto avoid the seeing e ect isthe `three-dimensional sp ectroscopy' technique, with which a data cub e can b e obtained with a single exp osure.However,sincethenumberofdatapoints(orpixels)obtainedwithasingleexp osureislimited,eneedtosacri cethespatialpixelnumbersand/orwavelength coerageinthreedimensionalsp ectroscopy.For instance, the Multi-channel Subtractive Double Pass sp ectrograph1(MSDP), which is a pioneering three-dimensionalsp ectroscopy instrumentinsolar physics and has b een installed in various telescop es,2can takeimages atninewavelengthscoering anabsorption linewithsingleexp osure,butits eldofviewisratherlimited.Therefore,thedataacquisitionwithmultipleexp osuresscanningaroundanabsorptionlineatunable lteristhemostwidelyusedtechniquetoobtaindatacub e.Therecentdevelopmenoflargeformat CCDs, whichcovers a wide eld of view with a high-spatial resolution, and the developmentoftunable lters, esp ecially tunable Fabry-Perot lters in addition to Lyot lters, helps such a technique.However, imageshifts b etween the subsequent exp osures due to the seeing e ect pro duce false sp ectral signals and they makequantitative sp ectral analyses di cult.Sp ectroheliographs are classic instruments to get mono chromatic images.It is necessary to scan the solar im-age to get two-dimensional images, and it takes some time even to get a single mono chromatic image.Therefore,asp ectroheliographhaslittleadvantage to ltergraphsystem forobtainingsinglemono chromatic image.However, we can get full sp ectral information for a slitp osition with a single exp osure using a sp ectrograph.Therefore we can carry out sp ectral analyses b eing free from the image motion due to the seeing e ect, whilethe seeing e ect gives somewhat distorted mono chromatic images in the case of sp ectroheliographs.Therefore,a sp ectroheliograph is a b etter alternative to get a set of mono chromatic images for quantitative analyses.Forthis reason, precise imaging sp ectrop olarimetries to make magnetograms are done with sp ectroheliographs (theFurther author information:E-mail:hanaoka@solar.mtk.nao.ac.jp