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The performance of a deformable mirror with 188 electrodes is reported in this paper. The deformable mirrorhas been manufactured by CILAS for a new adaptive optics system at Subaru Telescope equipped with laser-guide-star. The type of deformable mirror is bimorph PZT with the blank diameter of 130 mm (beam size 90mm).Keywords: adaptive optics system, deformable mirror, bimorph 1. INTRODUCTION A project updating the adaptive optics (AO) system of Subaru Telescope 1,2 to a laser-guide-star adaptive optics(LGSAO) 3,4 is going on. One of the key components in the system is a deformable mirror (DM). The DM consistsof two PZT plates in the con“guration of bimorph and has 188 control electrodes in-between. An optical-qualityglass plate is glued on the mirror side of the DM and another glass plate on the other side (wiring side) tokeep symmetrical structure. Finite element analysis (FEA) had been performed to “nalize the speci“cation, bytaking account of trade-o between stroke and the size of each electrode, between resonance frequency and thediameter of blank (Ref.5). The DM has been manufactured by CILAS based on the speci“cation. In this paper,the performance of the DM is presented together with comparison between the test results and FEA.

We developed a high power and high beam quality 589 nm coherent light source by sum-frequency generation in order to utilize it as a laser guide star at the Subaru telescope. The sum-frequency generation is a nonlinear frequency conversion in which two mode-locked Nd:YAG lasers oscillating at 1064 and 1319 nm mix in a nonlinear crystal to generate a wave at the sum frequency. We achieved the qualities required for the laser guide star. The power of laser is reached to 4.5 W mixing 15.65 W at 1064 nm and 4.99 W at 1319 nm when the wavelength is adjusted to 589.159 nm. The wavelength is controllable in accuracy of 0.1 pm from 589.060 and 589.170 nm. The stability of the power holds within 1.3% during seven hours operation. The transverse mode of the beam is the TEM00 and M 2 of the beam is smaller than 1.2. We achieved these qualities by the following technical sources; (1) simple construction of the oscillator for high beam quality, (2) synchronization of mode-locked pulses at 1064 and 1319 nm by the control of phase di!erence between two radio frequencies fed to acousto-optic mode lockers, (3) precise tunability of wavelength and spectral band width, and (4) proper selection of nonlinear optical crystal. We report in this paper how we built up each technical source and how we combined those.

We are developing Laser Guide Star Adaptive Optics (LGSAO) system for Subaru Telescope at Hawaii, Mauna Kea. We achieved an all-solid-state 589.159 nm laser in sum-frequency generation. Output power at 589.159 nm reached 4W in quasi-continuous-wave operation. To relay the laser beam from laser location to laser launching telescope, we used an optical fiber because the optical fiber relay is more flexible and easier than mirror train. However, nonlinear scattering effect, especially stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS), will happen when the inputted laser power increases, i.e., intensity at the fiber core exceed each threshold. In order to raise the threshold levels of each nonlinear scattering, we adopt photonic crystal fiber (PCF). Because the PCF can be made larger core than usual step index fiber (SIF), one can reduce the intensity in the core. We inputted the high power laser into the PCF whose mode field diameter (MFD) is 14 μm and the SIF whose MFD is 5 μm, and measured the transmission characteristics of them. In the case of the SIF, the SRS was happen when we inputted 2 W. On the other hand, the SRS and the SBS were not induced in the PCF even for an input power of 4 W. We also investigated polarization of the laser beam transmitting through the PCF. Because of the fact that the backscattering efficiency of exciting the sodium layer with a narrowband laser is dependent on the polarization state of the incident beam, we tried to control the polarization of the laser beam transmitted the PCF. We constructed the system which can control the polarization of input laser and measure the output polarization. The PCF showed to be able to assume as a double refraction optical device, and we found that the output polarization is controllable by injecting beam with appropriate polarization through the PCF. However, the Laser Guide Star made by the beam passed through the PCF had same brightness as the state of the polarization.

The configuration proposed in this paper is a configuration of "quasi-intracavity sum-frequency-mixing" combined systems of intra- and extracavity frequency conversion. The configuration is an attractive method to achieve higher power SFG. Our approach in progress is to construct an intracavity system at 1319 nm and to combine 1064 nm beam from outside of the 1319 nm cavity with optics and a nonlinear optical crystal of lower losses at 1319 nm. The approach will compensate the lower power of 1319 nm compared with 1064 nm power and achieve 589 nm output power at the 4-10 W level at 589 nm in SFG.

6.3 W coherent yellow light generation at 589.159 nm was achieved by the sum frequency generation of two mode-locked lasers with wavelengths of 1064nm and 1319 nm for the laser guide star of the astronomical telescope.

We present 3 um spectroscopy of the carbon-rich proto-planetary nebulae IRAS 04296+3429 and IRAS 05341+0852 conducted with the adaptive optics system at the Subaru Telescope. We utilize the nearly diffraction-limited spectroscopy to probe the spatial extent of the hydrocarbon dust emitting zone. We find a hydrocarbon emission core extending up to 100--160 mas from the center of IRAS 04296+3429, corresponding to a physical diameter of 400--640 AU, assuming a distance of 4 kpc. On the other hand, we find that IRAS 05341+0852 is not spatially resolved with this instrumentation. The physical extent of these proto-planetary nebulae, along with the reanalyzed data of IRAS 22272+5435 published previously, suggests a correlation between the physical extent of the hydrocarbon dust emission and the spectral evolution of the aliphatic to aromatic features in these post-AGB stars. These measurements represent the first direct test of the proposed chemical synthesis route of carbonaceous dust in the circumstellar environment of evolved stars., Comment: 6 pages, 4 figures, Accepted for publication in the Astrophysical Journal

We report a high-stable and high-beam-quality 589.158 nm radiation in sum-frequency generation using LD-side-pumped Nd:YAG laser oscillators. Average ouput power reached 4.6 W and it was stable within plusmn2.2% for 8 hours.

4 W coherent yellow light generation at 589 nm was achieved by sum frequency generation of two mode-locked lasers generating at 1064 nm and 1319 nm for laser guide star of the astronomical telescope.

We proposed a novel configuration for efficient generation of coherent 589-nm light by sum-frequency generation mixing 1064 and 1319 nm emitted from two continuous-wave Nd:YAG lasers. A 5-mm-long periodically-poled KTiOPO4 was used as a nonlinear optical crystal and it was set in the 1064-nm-Nd:YAG laser. Output beam oscillated from the 1319-nm-Nd:YAG laser was superimposed on a propergation axis of 1064-nm beam stored in the 1064-nm laser using a beam combiner from outside of the laser.?Output power of sum frequency reached to 1 W and it was ten times higher than that by extracavity sum-frequency generation using the same appatatus.

Quasi-intracavity sum-frequency-generation was demonstrated. Output power at 589 nm reached to 1 W mixing 1064 and 1319 nm of cw Nd:YAG lasers. The output power was ten times higher than that by extracavity sum-frequency-generation.

The performance of the Cassegrain Adaptive Optics (AO) system of the 8.2 m Subaru Telescope is reported. The system is based on a curvature wavefront sensor with 36 photon-counting avalanche photodiode modules and a bimorph wavefront correcting deformable mirror with 36 driving electrodes. This AO system has been in service since 2002 April for two open-use instruments, an infrared camera and spectrograph (IRCS) and a coronagraph imager with adaptive optics (CIAO). The Strehl ratio in the K-band is around 0.3 when a bright guide star is available under 0".4 seeing condition. High sensitivity of the wavefront sensor allows significant improvement in the image quality, even for faint guide stars down to R=18 mag. The design of the new Nasmyth Adaptive Optics system with 188 control elements under construction is described. This new system with fivefold increase in the number of control elements will provide twice higher Strehl ratio of 0.7. To increase the sky coverage for this new system, a power laser system to produce an artificail guide star in the upper atmosphere is also under construction. The AO system with laser guide capability enables the coverage up to 80% of the entire sky and offers diffraction limited observation for almost any target in the sky. An all solid-state 4W laser to generate the sodium D line emission by summing the two YAG laser frequencies is under development. The generated laser beam is tranmitted through a photonic crystal fiber to the laser launching telescope attached at the backside of the secondary mirror. Expected performance of this laser guide Nasmyth AO system is shown.

The laser guide star adaptive optics (AO) module for the Subaru Telescope will be installed at the f/13.9 IR Nasmyth focus, and provides the compensated image for the science instrument without change of the focal ratio. The optical components are mounted on an optical bench, and the flexure depending on the telescope pointing is eliminated. The transferred field of view for the science instrument is 2 arcmin diameter, but a 2.7 arcmin diameter field is available for tip-tilt sensing. The science path of the AO module contains five mirrors, including a pair of off-axis parabolic mirrors and a deformable mirror. It has also three additional mirrors for an image rotator. The AO module has a visible 188-element curvature based wavefront sensor (WFS) with photon-counting avalanche photodiode (APD) modules. It measures high-order terms of wavefront using either of a single laser (LGS) or natural guide star (NGS) within a 2 arcmin diameter field. The AO module has also a visible 2 x 2 sub-aperture Shack-Hartmann WFS with 16 APD modules. It measures tip-tilt and slow defocus terms of wavefront by using a single NGS within a 2.7 arcmin diameter field when a LGS is used for high-order wavefront sensing. The module has also an infrared 2 x 2 sub-aperture Shack-Hartmann WFS with a HgCdTe array as an option. Both high- and low-order visible WFSs have their own guide star acquisition units with two steering fold mirrors. The AO module has also a source simulator. It simulates LGS and NGS beams, simultaneously, with and without atmospheric turbulence by two turbulent layer at about 0 and 6 km altitudes, and reproduces the isoplanatism and the cone effect for the LGS beam.

We present the development status of the laser system for Subaru Laser Guide Star Adaptive Optics System. We are manufacturing the quasi-continuous-wave sum frequency laser as a prototype. The optical efficiency of sum frequency generation normalized by the mode-locked fundamental YAG (1064 nm) laser output power is achieved to be 14 % using the non-linear crystal, periodically poled potassium titanyl phosphate (PPKTP). Output power at sodium D2 line was about 260 mW. The optical relay fiber and the laser launching telescope are also described in this paper. For the optical relay fiber, we are testing an index guided photonic crystal fiber (PCF), whose core material is filled by fused silica, and whose clad has close-packed air holes in two dimension. The coupling efficiency was evaluated as about 80 % using 1mW He-Ne laser. We introduce the design of laser launching telescope (LLT), which is a copy of VLT laser launching telescope, and the interface to the Subaru Telescope.

The laser guide star adaptive optics (AO) system for Subaru Telescope is presented. The system will be installed at the IR Nasmyth platform, whereas the current AO system with 36 elements is operating at the Cassegrain focus. The new AO system has a 188 element wavefront curvature sensor with photon counting APD modules which is the largest control element curvature sensor system ever. The system will have 4-10 W solid state sum-frequency laser to generate a laser guide star. The laser launching telescope with 50 cm aperture will be installed at behind the secondary mirror. The laser unit will be installed on the third floor of the dome and the laser beam will be transferred to the laser launching telescope using single mode photonic crystal fiber cable. The field of view of the optics is 2.7 arcmin to maximize the probability to find tilt guide stars for laser guide star operation. The expected Strehl ratio as raw AO performance is 0.46 at H-band under 0.60" seeing with 12 th mag guide star, and 0.71 for 8 th mag stars. New wavefront modulation technique, dual stroke membrane mirror control, is developed to reduce the tilt error which is more dominant for curvature sensor AO system. The superb contrast imaging capability will be expected as natural guide star system. The first light as the natural guide star system is planned in March 2006, the laser first light will be expected in March 2007.

The Subaru Telescope LGSAO system is a 188 elements curvature AO system currently under construction, and scheduled to have first light in March 2006 for the Natural Guide Star mode and March 2007 for the Laser Guide Star mode. A particularity of this system will be to perform curvature wavefront sensing with several extra-pupil distances, which significantly improves the closed-loop performance. An overview of the predicted performance of the system is given for Natural Guide Star and Laser Guide Star modes.

We have measured near-infrared colors of the binary Kuiper Belt object (KBO) 1998 WW31 using the Subaru Telescope with adaptive optics. The satellite was detected near its perigee and apogee (0.18″ and 1.2″ apart from the primary). The primary and the satellite have similar H-K colors, while the satellite is redder than the primary in J-H. Combined with the R band magnitude previously published by Veillet et al., 2002, the color of the primary is consistent with that of optically red KBOs. The satellite’s R-, J-, H-colors suggest the presence of ~1μm absorption band due to rock-forming minerals. If the surface of the satellite is mainly composed by olivine, the satellite’s albedo is higher value than the canonically assumed value of 4%.

Quasi-continuous-wave generation at 589 nm in periodically poled KTP was achieved by sum-frequency mixing of synchronized mode-locked pulses emitted at 1064 and 1319 nm from two mode-locked Nd:YAG lasers. As acousto-optic mode lockers operated by the same frequency were used for mode locking, pulse trains were well synchronized with phase control of the radio frequency. The maximum output power at 589 nm was 260 mW mixing 1.9 W at 1064 nm and 0.88 W at 1319 nm. Conversion efficiency was reached to 14%, even for single-pass pumping using 5-mm-long periodically poled KTP.

Adaptive optics imaging of the bright visual T Tauri binary AS 353 with the Subaru Telescope shows that it is a hierarchical triple system. The secondary component, located 5.6" south of AS 353A, is resolved into a subarcsecond binary, AS 353Ba and Bb, separated by 0.24". Resolved spectroscopy of the two close components shows that both have nearly identical spectral types of about M1.5. Whereas AS 353A and Ba show clear evidence for an infrared excess, AS 353Bb does not. We discuss the possible role of multiplicity in launching the large Herbig-Haro flow associated with AS 353A., AASTeXv5.0, 21 pages, 5 figures, Astronomical Journal, in press

We introduce a near-infrared camera named coronagraph imager with adaptive optics (CIAO) mounted on the Subaru 8m telescope. Combined with the Subaru 36 elements adaptive optics (AO), CIAO can produce nearly diffraction limited image with approximately 0.07 arcsec FWHM at K band and high dynamic range imaging with approximately 10 mag difference at 1 arcsec separation under typical seeing conditions. We have carried out performance tests of imaging without and with coronagraph mask since its first light observation held on 2000 February. Because of limited weather conditions, the performance under best seeing conditions has not been tested yet. At a typical natural seeing condition of 0.4 - 0.8 arcsec, halo component of PSF using 0.2 - 0.8 arcsec mask can be reduced up to 70% comparing with that without mask using AO. Even after correction, residual wave front error has typically 1.2 rad2 which corresponds to the Strehl ratio of approximately 0.3 at K band. Such wave front errors degrades the image quality; this is a common problem of coronagraph on the ground-based telescope with non high-order AO. Nevertheless we emphasize that there are various advantages on our coronagraph: the clean PSF of CIAO, reduction of readout noise, and less effect of detector memory problem. Compared with coronagraphs on smaller telescopes, the PSF shape is sharper and it brings higher detectability of sources around bright objects.

We measured the Rayleigh scattered light from the laser beam launched from Keck II telescope. The illumination at the pupil of Subaru telescope was recorded using the APDs of the Subaru AO system wavefront sensor. Since the field of view of our wavefront sensor is only 5 arcsec in diameter, it was possible to follow the laser beam as it travels across the telescope pupil. The maximum surface brightness of the laser beam is estimated at 16.2 mag/arcsec2.

We present an overview of Subaru Cassegrain adaptive optics system and its performance verified at the engineering run. The system is based on a curvature wavefront sensor with 36-element sub-apertures and a bimorph deformable mirror with identical number of elements. We had the first light in Dec. 2000. The AO system has been in service for two instruments, IRCS; infrared camera and spectrograph, and CIAO; coronagraph imager with adaptive optics. The Strehl ratio at the K band is around 0.30 under 0.4- 0.5 arcsec K-band seeing condition for bright guide stars. The sensitivity of the wavefront sensor is so high that we have significant improvement of image quality even for a faint guide star down to R=18 th magnitude. The measurement of stars in a globular cluster suggests an isoplanatic angle, about 40 arcsec, wider than that expected from the equivalent turbulence layer assumed at the height of 6.5 km. The system has been offered for common use since Apr. 2002. Some scientific results using this AO system are shown in this paper.

Subaru AO a 36 element Curvature Sensor was developed for the 8.2m Subaru Telescope operated by the National Astronomical Observatory of Japan. The system is already over one year on sky and now offered for open use observation. During the time from first light to open use we did major changes in software to operate the instrument more easy and efficient and also improved the performance by tuning the control loop. We will discuss the software model and show what we learned and how we managed the crucial points of this implementation. After this we will have a look at how we can improve the system further.

A 36-elements curvature adaptive optics (AO) system has been operating on the Subaru telescope for about one and a half year. We achieved a Strehl ratio of 0.3 in the K-band, which is a rather smaller value than we expected. While we are investigating the discrepancy between the obtained performance and the simulated performance of the current AO system and we are also improving the current AO system in terms of the Strehl performance and the observing efficiency. Meanwhile we have started to plan a next generation of Subaru AO system. Two major upgrades are proposed in this paper. One is to increase the number of subapertures as much as possible. Practically, the number of subapertures lies between 100 and 200. The size of subaperture becomes half to one-third of that of the current system and we expected that the K-band Strehl ratio will improve to more than 0.6. The first light of the higher order curvature AO system is scheduled for 2004. Another upgrade plan is to use a laser guide star (LGS). A single LGS is projected at the sodium layer with an output power of 4 W. Conceptual designs for the laser system, beam relay system, laser launching telescope and control system have begun. The first test of launching laser from Subaru telescope will be in 2005.

We present a note on low to medium resolution spectroscopy using adaptive optics (AO) system. A special focus is put on the problem of spectral slope variations. In principle a stellar image compensated by AO has a varying point spread function (PSF) strongly dependent on the observing wavelength. Even when the AO is working perfectly, the fraction of the energy in a finite size slit will change with the wavelength. The performance of AO correction is very sensitive to the observing conditions. Spectral slope variations directly connected to the wavelength dependency of the enclosed energy in the slit. Those features common and relatively harmless in conventional spectroscopy such as temporal variation in the seeing, brightness of the targets, imperfect slit peaking, atmospheric differential refraction, and fixed aperture size at spectral extraction, all introduce artificial continuum slopes. The degree of uncertainty in the spectral slope could be serious enough to interfere the observing goals in AO spectroscopy. A case for a spectroscopic observation for low mass stars is presented to demonstrate the problem. We found a steep continuum slope that is unrealistic for a low mass star. We undertook laboratory experiments with a calibration source in the AO system to test if the unrealistic continuum slope could be accounted for by the varying AO performance. In the experiments the "bluing" of the continuum slopes have been confirmed when the light source is dropping off of the slit or the wavefront reference source is faint. The effects are also qualitatively reproduced with calculations done by an AO simulation code.

We present the first spectroimagery of extended molecular atmosphere of Mira spatially resolved by adaptive optics system. We found the molecular atmosphere of H2O, CO and CO2 is extended to about 40 mas. The presence of extended molecular layer has been revealed by recent infrared spectroscopic studies with space borne telescope ISO. The physical extent in our observation is consistent with their studies. The new technique that resolves objects in wavelength and in space simultaneously is proved to be very sensitive to the extended component respect to the continuum photosphere, because the time variable seeing effect is mostly canceled by relative measurement of the image size

We present high angular resolution spectra taken along the jets from L1551 IRS 5 and DG Tau obtained with the Subaru Telescope. The position-velocity diagrams of the [Fe II] λ 1.644 μm emission line revealed remarkably similar characteristics for the two sources, showing two distinct velocity components separated from each other in both velocity and space with the entire emission range blueshifted with respect to the stellar velocity. The high velocity component (HVC) has a velocity of -200 -300 km s-1 with a narrow line width, while the low velocity component (LVC) is around -100 km s-1 exhibitinig a broad line width. The HVC is located farther away from the origin and is more extended than the LVC. Our results suggest that the HVC is a well-collimated jet originating from the region close to the star, while the LVC is a widely-opened wind accelerated in the region near the inner edge of the accretion disk.

We made aperture masking optical interferometry experiments using up to 30 apertures and with a tip-tilt correction of wavefront error. We examined the performance of minimum redundant configurations of 11–30 sub-apertures on the pupil plane mask. These configurations have two advantages; the redundancy noise is as small as realized in non-redundant masking method, and the uv-coverage is as high as in speckle interferometry enabling to get reconstructed images without mask exchange. We also examined the effect of tip-tilt wavefront correction within a telescope pupil in front of the aperture masking optics. The light coherency between sub-apertures was shown to increase by the correction.

An adaptive optics system was developed for the 8.2-m Subaru Telescope operated by the National Astronomical Observatory of Japan on the summit of Mauna Kea in Hawaii. The system saw first light on 2 December 2000 and achieved diffraction limited imaging in the K- and L- band. The system is located at the Cassegrain focus of Subaru and can feed either IRCS, an infrared camera and spectrograph (used for first light) or CIAO, an infrared coronagraphic imager. The system features a 36-elements curvature sensor using avalanche photo diodes and a 36-electrodes bimorph deformable mirror. The curvature sensor and deformable mirror were custom designed for an optimum match. Wavefront sensing is performed in the visible range while AO-corrected observations are made in the infrared. In this paper the first AO observations are described and the system performances are compared with the design values. A comparison is also made with other existing AO systems. First scientific demonstrations are shown.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

著者人数: 58名, Accepted: 2014-01-16, 資料番号: SA1004554000

Prototype laser guide star system for Subaru telescope has been developed at Communications Research Laboratory (CRL). The laser system comprises two commercially available lasers: a modified continuous wave (CW) dye laser and a 10 W all-solid CW laser of 532 nm wavelength for pumping the dye laser. The natural guide star adaptive optics system for Subaru telescope on Cassegrain focus will be upgraded to a laser guide star adaptive optics system using this laser system. The experiment of transmitting laser beam to the sodium layer is performed at CRL using a 1.5 m telescope. The laser beam is emitted from a 20 cm telescope mounted next to the 1.5 m telescope. A laser guide star is observed by a cooled CCD camera, which is equipped on the Nasmyth platform. We report the preliminary results of the experiment of observing a sodium laser guide star.

The introduction of the 'hybrid electrode' has proven to successfully simplify both the electrode design and the requirements on the electrical driver of liquid crystal optical devices. In this paper, we present the design and summarize some experimental results with respect to liquid crystal lenses and lens arrays employing the hybrid electrode structure. We further introduce the design of the circular hybrid electrode structure that brought forth, to our knowledge, the first single-layer liquid crystal spherical lens array with quadratic lens apertures.

We have been studying a high-bit-rate satellite laser communications system between a ground station and a geostationary satellite, named high-speed optical feeder- link system. An adaptive optics (AO) is the best solution to compensate the degradation of the laser beam quality due to atmospheric turbulence and to realize such a high-bit-rate laser communication system.

This paper reports the application of an adaptive optics (AO) system to our ground-to-satellite laser communication system. We believe that the AO system is one of the best solutions to compensate the degradation of the laser beam due to an atmospheric turbulence and to realize a high bit-rate laser communication system. In the first stage of developing and designing the AO system, we have measured an atmospheric turbulence at Communications Research Laboratory (CRL), located in the west suburb of Tokyo. It shows that Fried's coherence length is about 5 cm in winter and 9 cm in summer at 0.8 µm observing wavelength. We also simulated the AO performance of the laser communication system using our results of the atmospheric measurement.

We propose a satellite laser communication system between a ground station and a geostationary satellite, named high- speed optical feeder link system. It is based on the application of (a) high-speed optical devices, which have been developed for ground-based high-speed fiber-optic communications, and (b) the adaptive optics which compensates wavefront distortions due to atmospheric turbulences using a real time feedback control. A link budget study shows that a system with 10-Gbps bit-rate are available assuming the state-of-the-art device performance of the Er-doped fiber amplifier. We further discuss preliminary measurement results of the atmospheric turbulence at the telescope site in Tokyo, and present current study on the design of the key components for the feeder-link laser transceiver.

Liquid crystal waveplates are known as efficient phase or wavefront modulators for applications requiring the active control of laser beams such as beam steering, focusing or diffraction. In developing such devices researchers have used so far two types of electrode structures: (1) the discrete structure where the liquid crystal is modulated by means of a large number of independent narrow stripe-shaped low-resistive electrodes, and (2) the continuous structure where broad electrodes with areas of different resistivities modulate the liquid crystal via a linear or nonlinear voltage gradient generated in the electrode plane. The former approach has the advantage of high transmission efficiency and unproblematic fabrication of the electrodes. The huge number of electrodes requires however a high expenditure in fabricating the complex LC driver. The latter approach keeps down the complexity of the LC driver, however, a high optical throughput has not yet been reported. In this paper, we present an electrode design that aims at combining the advantages found in both approaches. The usefulness of the novel electrode design was verified for the first time in an experiment demonstrating the nearly diffraction limited performance of an adaptive LC microlens array.

Debris disks around young main-sequence stars often have gaps and cavities which for a long time have been interpreted as possibly being caused by planets. In recent years, several giant planet discoveries have been made in systems hosting disks of precisely this nature, further implying that interactions with planets could be a common cause of such disk structures. As part of the SEEDS high-contrast imaging survey, we are surveying a population of debris disk-hosting stars with gaps and cavities implied by their spectral energy distributions, in order to attempt to spatially resolve the disk as well as to detect any planets that may be responsible for the disk structure. Here we report on intermediate results from this survey. Five debris disks have been spatially resolved, and a number of faint point sources have been discovered, most of which have been tested for common proper motion, which in each case has excluded physical companionship with the target stars. From the detection limits of the 50 targets that have been observed, we find that beta Pic b-like planets (~10 Mjup planets around G--A-type stars) near the gap edges are less frequent than 15--30%, implying that if giant planets are the dominant cause of these wide (27 AU on average) gaps, they are generally less massive than beta Pic b., 17 pages, 9 figures, accepted for publication in ApJ

We present a spatially resolved imaging analysis of a three-component gravitationally lensed quasar at z = 3.91, APM 08279+5255, in the L0and M 0-bands, and a narrow band centered at 3.05 m using the 188-element adaptive optics system on the Subaru Telescope. The third, faintest quasar image, component C, has been clearly resolved in all of these bands for the first time. All of the three components are point sources in all three bands. No new component, neither a fourth quasar image nor a lens galaxy, was discovered. The observed bands correspond to the long-wavelength end of the optical power-law continuum of the source quasar in its rest frame, and are little contaminated by strong emission lines like H . The measured flux ratio of components C to B is shown to be constant in all of the observed bands, and its achromatic nature agrees well with preceding work done at short nearinfrared wavelengths one decade ago. On the other hand, the flux ratio of components A to B shows an increase from that of past measurements. This could be ascribed to a microlensing event.

We present Subaru/HiCIAO H-band high-contrast images of the debris disk around HIP 79977, whose pres- ence was recently inferred from an infrared excess. Our images resolve the disk for the first time, allowing characterization of its shape, size, and dust grain properties. We use angular differential imaging (ADI) to reveal the disk geometry in unpolarized light out to a radius of ~2", as well as polarized differential imaging (PDI) to measure the degree of scattering polarization out to ~1.5". In order to strike a favorable balance between suppression of the stellar halo and conservation of disk flux, we explore the application of principal component analysis (PCA) to both ADI and reference star subtraction. This allows accurate forward modeling of the effects of data reduction on simulated disk images, and thus direct comparison with the imaged disk. The resulting best-fit values and well-fitting intervals for the model parameters are a surface brightness power-law slope of S_out = -3.2 [-3.6,-2.9], an inclination of i = 84{\deg} [81{\deg},86{\deg}], a high Henyey-Greenstein forward-scattering parameter of g = 0.45 [0.35, 0.60], and a non-significant disk-star offset of u = 3.0 [-1.5, 7.5] AU = 24 [-13, 61] mas along the line of nodes. Furthermore, the tangential linear polarization along the disk rises from ~10% at 0.5" to ~45% at 1.5". These measurements paint a consistent picture of a disk of dust grains produced by collisional cascades and blown out to larger radii by stellar radiation pressure., Comment: 6 pages, 4 figures, 1 table. Accepted for publication in ApJ Letters

We describe Algorithms for Calibration, Optimized Registration, and Nulling the Star in Angular Differential Imaging (ACORNS-ADI), a new, parallelized software package to reduce high-contrast imaging data, and its application to data from the SEEDS survey. We implement several new algorithms, including a method to register saturated images, a trimmed mean for combining an image sequence that reduces noise by up to ~20%, and a robust and computationally fast method to compute the sensitivity of a high-contrast observation everywhere on the field-of-view without introducing artificial sources. We also include a description of image processing steps to remove electronic artifacts specific to Hawaii2-RG detectors like the one used for SEEDS, and a detailed analysis of the Locally Optimized Combination of Images (LOCI) algorithm commonly used to reduce high-contrast imaging data. ACORNS-ADI is written in python. It is efficient and open-source, and includes several optional features which may improve performance on data from other instruments. ACORNS-ADI requires minimal modification to reduce data from instruments other than HiCIAO. It is freely available for download at www.github.com/t-brandt/acorns-adi under a BSD license., Comment: 15 pages, 9 figures, accepted to ApJ. Replaced with accepted version; mostly minor changes. Software updated

We present the near-infrared images and spectra of four silhouette disks in the Orion Nebula Cluster (ONC; M42) and M43 using the Subaru Adaptive Optics system. While d053-717 and d141-1952 show no water ice feature at 3.1 micron, a moderately deep (tau~0.7) water ice absorption is detected toward d132-1832 and d216-0939. Taking into account the water ice so far detected in the silhouette disks, the critical inclination angle to produce a water ice absorption feature is confirmed to be 65-75deg. As for d216-0939, the crystallized water ice profile is exactly the same as in the previous observations taken 3.63 years ago. If the water ice material is located at 30AU, then the observations suggest it is uniform at a scale of about 3.5AU., 28 pages, 11 figures, Accepted for publication in AJ

SUBARU telescope with 8.2 m diameter is being constructed atop Mauna Kea in the Hawaii island. It employs the thin-meniscus primary mirror that is supported by 260 actuators, providing the almost perfect surface figure for near infrared imaging. The atmospheric turbulence is now the dominant origin of image degradation. Therefore, the adaptive optics (hereafter AO) system is essential equipment for large ground telescopes.