This PDF file contains the front matter associated with SPIE Proceedings Volume 6691, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

TThe European Southern Observatory (ESO) and Durham University's Centre for Advanced Instrumentation (CfAI) have progressed the 'Standard Platform for Adaptive optics Real-Time Applications' (SPARTA) to a preliminary design which successfully passed review in July 07. SPARTA's Real-Time Control box contains a mixture of processors, Digital Signal Processors and Field Programmable Gate Arrays (FPGA). The card selected in the design to host SPARTA's FPGA based Wavefront Processing Unit (WPU) is the VMETRO dual processor, dual FPGA VPF1 board. CfAI benchmarked this card along with the VMETRO Zero Latency Switch Card to assess their suitability for the SPARTA design. The VPF1 benchmark tests summarised in this paper includes: transfering data between FPGAs, between the FPGAs and PPCs (with and without the TransComm controller), from PPC to an external host via Ethernet and finally from the FPGA optical transceiver using CfAI's Serial Front Panel Data Port (sFPDP) core. Results show that the VPF1 is suitable to use as a WPU host card as the measured 280 MB/s FGPA to PPC TransComm data rates easily cope with SPARTA's maximum requirement of 30 MB/s. Using the VPF1 as a "back-end" controller introduces a latency of 17μs, which is greater than the original requirements of 12μs but still acceptable. The conclusion of the benchmarking tests and the design review is that the VPF1 and Zero Latency Switch have been selected for use in SPARTA.

ASSIST - The Adaptive Secondary Setup and Instrument STimulator is a test setup to verify the operation of three elements of the VLT Adaptive Optics Facility, namely the Deformable Secondary Mirror (DSM) and the two AO systems using this DSM, the AO system for the visible light integral field spectrograph MUSE (GALACSI) and the AO system for the IR wide field imager HAWK-I (GRAAL). To support the testing of these elements, ASSIST will provide both an interferometry setup for testing the DSM as well as a full atmospheric turbulence simulator and star simulator to mimic the conditions at the telescope. To test the instruments using the DSM, the output beam is matched the output beam of the VLT telescope, including the correct exit-pupil and high-quality imaging and a similar hardware interface is provided. Since one of the modes to be verified is nearly diffraction limited, also the thermal and vibrational stability are very important, with strong constraints on both the mechanical as well as the optical design.

We present the design of a new high-resolution near-infrared survey camera that will take advantage of the wide corrected field afforded by the 6.5 m MMT's new multi-laser ground-layer adaptive optics (GLAO) system. GLAO technology will correct for turbulence close to the telescope aperture where typically 1/2 to 2/3 of the total atmospheric turbulence lies and is expected to deliver image widths of 0.1-0.2 arc seconds in the near-infrared across a wide range of seeing conditions. The new camera will use a 2 by 2 mosaic of JWST NIRCam detectors, 2048 x 2048 arrays sensitive from 0.6 - 2.5 μm based on Teledyne's HgCdTe HAWAII-2RG detector technology. The camera has a 4 arc minute square field, giving a plate scale of approximately 0.06 arc seconds/pixel, critically sampling the GLAO PSF. In addition, high resolution (0.25 arc seconds or better) multi-object spectroscopy can be supported with cold slit masks inside the dewar; allowing potentially hundreds of spectra to be obtained at once with resolutions of up to 10,000.

We present a method of calibrating nonlinear Shack-Hartmann wavefront sensors to enable open-loop wavefront sensing of atmospheric turbulence. Involving a two-dimensional raster scan of a point source behind a telescope's primary, this method is robust to aliasing, non-common path errors, linearity error, and truncation error. We have implemented this technique on the UCO/Lick Laboratory for Adaptive Optics Multi-Conjugate AO (MCAO) and Multi-Object AO (MOAO) testbed. This testbed has 5 laser guide stars with star-oriented Shack-Hartmann wavefront sensors that have 4x4 pixel subapertures. We show that the disagreement between these multiple wavefront sensors on a simulated 10 meter telescope is decreased from 0.80 radians to 0.30 radians RMS for a full atmosphere (0.6" seeing) with our linearity calibration. This linearity calibration enables simulation of open-loop MOAO with good Strehl (36% with a simulated science wavelength of 950 nm on-axis) on a 10 meter aperture. We present a complete error budget for this case, with all budget terms empirically verified through interferometric methods. We verify that the tomographic error (due to blind modes) as empirically measured on the testbed is consistent with that predicted by tomographic reconstructions of simulated atmospheres.

Laser beams for guide star generation are a potential hazard for aircraft. At the MMT telescope located on Mt. Hopkins in Southern Arizona, a constellation of five Rayleigh guide stars is created with a total of 25 W of projected power at 532 nm wavelength. We report operational results from an automatic system deployed at the MMT that is designed to detect aircraft and shut down the lasers if a collision with the beams appears likely. The system, building on a previous prototype, uses a wide-angle CCD camera mounted with a minimally unobstructed view to the optical support structure at the top of the telescope. A computer program reads the camera once every two seconds and calculates the difference between adjacent image pairs. The anti-collision beacons required on all aircraft by the Federal Aviation Administration appear as streaks in the field. If an airplane is detected, it is located in the field relative to the laser beam and its path is projected. If aircraft are detected near or appear that they will approach the beam, the laser's safety shutter is closed and warning messages are sent to the laser operator. Failsafe operation is assured by a "heart beat" signal continuously sent from the detection system to the laser controller, and by the fact that the safety shutter must be energized to open. In the event of a power failure, the system must be manually reset by the Laser Safety Officer before the laser beam can again be propagated.

Great strides have been made in recent years toward the goal of high-contrast imaging with a sensitivity adequate to detect earth-like planets around nearby stars. It appears that the hardware − optics, coronagraph masks, deformable mirrors, illumination systems, thermal control systems − are up to the task of obtaining the required 10^-10 contrast. But in broadband light (e.g., 10% bandpass) the wavefront control algorithms have been a limiting factor. In this paper we describe a general correction methodology that works in broadband light with one or multiple deformable mirrors by conjugating the electric field in a predefined region in the image where terrestrial planets would be found. We describe the linearized approach and demonstrate its effectiveness through laboratory experiments. This paper presents results from the Jet Propulsion Laboratory High Contrast Imaging Testbed (HCIT) for both narrow-band light (2%) and broadband light (10%) correction.

An accurate and timely model of the atmospheric turbulence profile is an important input into the construction of tomographic reconstructors for laser tomography adaptive optics (LTAO) and multi-conjugate adaptive optics (MCAO) using multiple guide stars. We report on a technique for estimating the turbulence profile using the correlations between the modal reconstructions of open-loop wavefront sensor (WFS) measurements from natural or laser guide stars. Laser guide stars can provide an estimate of the turbulence profile along the line of sight to any suitable science target. Open-loop WFS measurements, acquired at the MMT telescope, have been analyzed to recover an estimate of the C²_n profile. This open-loop WFS data can be used to yield turbulence estimates in near real-time, which can be used to update the tomographic reconstructor prior to closed-loop operation. This method can also be applied in closed-loop, using telemetry data already captured by multi-guide star adaptive optics (AO) systems, by computing estimates of the wavefront modal covariances from the closed-loop WFS residual error signals and the deformable mirror (DM) actuator positions. This will be of particular value when implemented with accurate position feedback from the AO system's DMs, rather than the input actuator commands, as is possible with an adaptive secondary mirror. We plan the first tests of the technique with the MMT's adaptive secondary and five Rayleigh laser guide stars.

The detection of extra-solar terrestrial planets requires the use of space-based high-contrast imaging. Stellar photon noise as well as light thrown about by system aberrations necessitate the use of a high quality light suppression system and a method for wavefront correction. We present here a wavefront estimation scheme to be used with estimate-based correction for the shaped pupil coronagraph. In order to properly estimate the field in a reimaged pupil plane, we employ the use of the iterative Gerchberg-Saxton estimation algorithm between it and a second-focus image plane. We utilize the correction algorithm to overcome an ambiguity inherent in Gerchberg-Saxton estimation.

Adaptive Optics improves image quality in telescopes, rapidly moving space objects and laser beam distortion correction through the atmosphere. Many approaches (LGS, GLAO, LTAO) have been demonstrated to address requirements for future telescopes (TMT, ELT). This effort, using Adaptive Wavelets, will reduce complexity and costly hardware, as well as address computation challenges. Wavelet-based phase determination is applied to interferograms and adaptive wavelet echo cancellation will be used to achieve phase conjugate distortion correction.

Despite promising results, Curvature wavefront sensing is usually not considered as an option for future AO systems such as AO systems for Extremely Large Telescopes (ELTs) or high order systems for the current generation of 8 to 10m telescopes. CWFS is generally thought to be useful only for low order systems, both for technical reasons (detector and DM technology) and fundamental reasons (noise propagation for high order curvature systems). I show in this paper that these worries are unjustified, and that, thanks to newly developed techniques and algorithms, CWFS is in fact much superior to more traditional Shack-Hartman wavefront sensing: (1) CWFS can be made extremely efficient, even for a high order system, thanks to a new "multi-stroke" curvature wavefront sensing mode (2) CWFS-based systems can efficiently utilize both piezo-stack type deformable mirrors and square pixel detector array, and there is therefore no reason to think that technological considerations limit CWFS-based systems to low-order correction (3) non-linear Fourier-based CWFS control algorithms can dramatically increase the performance of existing and future CWFS-based systems.

A few years ago the Air Force Research Laboratory developed a Self-Referencing Interferometer (SRI) wavefront sensor (WFS) that is able to accurately detect the magnitude and phase of propagating electromagnetic waves in a strong scintillation environment. This proved to be very useful in applications of adaptive optics when detecting light or transmitting laser beams through moderate to high turbulence. The SRI operates by interfering a beacon beam, which has been aberrated by atmospheric turbulence, with a reference beam having a known phase and detecting the intensity of the interference pattern. The phase of the beacon is then determined from those interference patterns. At least three different phases of a reference beam are needed to accurately determine the phase on the beacon beam, but four are preferable. These phases shift the reference beam by 0, π/2, π, and 3π/2. In this paper we examine the effects of phase shift errors. Our method can be extrapolated to any WFS utilizing the Carré algorithm with π/2 phase steps. These results show that the SRI is amazingly tolerable to phase shifting errors, specifically that an adaptive optic loop still closes even with a phase error 'epsilon' of nearly ±π/2. Even more unexpected, it is possible to increase Strehl over the nominally aligned system by as much as 11% in closed loop operation when phase errors are purposefully induced.

Adaptive optics is widely used in astronomy. Recently, most of newly built telescopes have adaptive optical systems. In order to apply adaptive optics into astronomical telescope, high-speed wavefront sensing is required. In high-speed operation, exposure time per frame of a sensor is quite short. In this case, optical intensity of one-frame image is pretty low. Thus signal-to-noise ratio of the wavefront sensor is also low. Therefore, in this case, noises such as readout noise and photon noise greatly influence the accuracy of wavefront sensing. The center of mass method is widely used due to its low computational cost. However it is very weak to noise. The correlation method is robust to noise. But the computational cost is expensive. In this paper, Multi-Resolution Correlation method is proposed. This method, by employing multi-resolution images, considerably reduces the computation time when compared to the FFT correlation method. Also the accuracy of Shack-Hartmann wavefront sensor using the proposed algorithm is proved to be almost same as that of the conventional correlation method. The verification is done through the simulation.

The large telescopes nowadays under development will have the adaptive optics systems fully integrated from the beginning of the project. These optics are in fact an essential component that is necessary for the full exploitation of the performances obtainable from the large optics foreseen in these instruments. Due to the large reflecting areas of these telescopes their adaptive optics systems will use probably thin segmented mirrors, assembled to create a single surface, placed along the optical train. Today, a number of telescopes (MMT, LBT, etc) have the monolithic secondary mirror of the instrument used as a component of the adaptive optic system. The technique used for the production of these single pieces thin mirror shells, typically having convex shape, is not well suited for the manufacturing of the large number of segments necessaries for the future telescopes. Infact, the procedure foresees the thinning of conventional thick mirrors, a technique expensive and time consuming. It is hence necessary to find a better approach able to produce thin optical segments in a cost effective way and with short delivery time. In this study, financed in the frame of OPTICON-FP6, the Astronomical Observatory of Brera (INAF-OAB) is investigating a technique for the manufacturing of these optical components that has the potential to fulfill these requirements. The curved optical segments that are under development will have a thickness of few mm and will be made in Borofloat^TM glass. The technique foresees the thermal slumping of thin glass segments using a high quality ceramic mold as a master to impart a precise shape to the glass. The initially flat glass segment is placed onto the mold and then, by means of a suitable thermal cycle, the material is softened so to copy the master shape. If necessary, at the end of the slumping is foreseen the correction of the eventual remaining errors using the Ion Beam Figuring technique. This paper describes the process of production of the optical segments and the status of the investigation.

The SPHERE is an exo-solar planet imager, which goal is to detect giant exo-solar planets in the vicinity of bright stars and to characterize them through spectroscopic and polarimetric observations. It is a complete system with a core made of an extreme-Adaptive Optics (AO) turbulence correction, pupil tracker and interferential coronagraphs. At its back end, an Infra-Red Dual-beam Imaging and Spectroscopy science module and an integral field spectrograph work in the Near Infrared (NIR) Y, J, H and Ks bands (0.95 - 2.32μm) and a high resolution polarization camera covers the visible (0.6 - 0.9 μm) region. We describe briefly the science goals of the instrument and deduce the top-level requirements. This paper presents the system architecture, and reviews each of the main sub-systems. The results of the latest end-to-end simulations are shown and an update of the expected performance is given. The project has been officially kicked-off in March 2006, it is presently undergoing Preliminary Design Review and is scheduled for 1st light in early 2011. This paper reviews the present design of SPHERE but focuses on the changes implemented since this project was presented the last time to this audience.

The laser guidestar system at the MMT Observatory has produced its first closed loop results and should be producing ground-layer corrected closed loop images within a few months. The LGS system at the MMT is one of few in the world that uses atmospheric Rayleigh scattering from reliable, low-cost lasers, and is unique in its use of a dynamic refocus technique to increase the telescope depth of field for increased return flux. The resulting 10 km depth of field introduces additional constraints on the minimum spot size for the beam projector design. The short exposure spot size as measured at the telescope cassegrain focus is 0.65 arcseconds in 0.59 arcsecond seeing in the visible. Additionally, a method to correct for image motion due to telescope vibrations using accelerometer data has been successfully implemented.

Over the past several years, experiments in adaptive optics involving multiple natural and Rayleigh laser guide stars have been carried out by our group at the 1.5 m Kuiper telescope and the 6.5 m MMT telescope. From open-loop data we have calculated the performance gains anticipated from ground-layer adaptive optics (GLAO) and laser tomography adaptive optics corrections. In July 2007, the GLAO control loop was closed around the focus signal from all five laser guide stars at the MMT, leading to a reduction in the measured focus mode on the laser wavefront sensor by 60%. For the first time, we expect to close the full high order GLAO control loop around the five laser beacons and a tilt star at the MMT in October 2007, where we predict image quality of < 0.2 arc seconds FWHM in K band (λ = 2.2 μm) over a 2 arc minute field. We intend to explore the image quality, stability and sensitivity of GLAO correction as a function of waveband with the science instrument PISCES. PISCES is a 1-2.5 µm imager with a field of view of 110 arc seconds, at a scale of 0.11 arc seconds per pixel. This is well matched to the expected FWHM performance of the GLAO corrected field and will be able to examine PSF non-uniformity and temporal stability across a wide field. FGD.

We describe the conceptual design of an advanced laser guide star facility (LGSF) for the Large Binocular Telescope (LBT), to be built in collaboration with the LBT's international partners. The highest priority goal for the facility is the correction of ground-layer turbulence, providing partial seeing compensation in the near IR bands over a 4' field. In the H band, GLAO is projected to improve the median seeing from 0.55" to 0.2". The new facility will build on the LBT's natural guide star AO system, integrated into the telescope with correction by adaptive secondary mirrors, and will draw on Arizona's experience in the construction of the first multi-laser adaptive optics (AO) system at the 6.5 m MMT. The LGSF will use four Rayleigh beacons at 532 nm, projected to an altitude of 25 km, on each of the two 8.4 m component telescopes. Initial use of the system for ground layer correction will deliver image quality well matched to the LBT's two LUCIFER near IR instruments. They will be used for direct imaging over a 4'×4' field and will offer a unique capability in high resolution multi-object spectroscopy. The LGSF is designed to include long-term upgrade paths. Coherent imaging at the combined focus of the two apertures will be exploited by the LBT Interferometer in the thermal IR. Using the same launch optics, an axial sodium or Rayleigh beacon can be added to each constellation, for tomographic wavefront reconstruction and diffraction limited imaging over the usual isoplanatic patch. In the longer term, a second DM conjugated to high altitude is foreseen for the LBT's LINC-NIRVANA instrument, which would extend the coherent diffraction-limited field to an arcminute in diameter with multi-conjugate AO.

A European Laser Guide Star (LGS) test facility is proposed for the 4.2m William Herschel Telescope (WHT) on La Palma. It will test the next-generation Adaptive Optics (AO) LGS technologies to aid risk mitigation of Extremely Large Telescope (ELT) LGS AO systems. In particular, critical scaling of current LGS AO technologies to ELT dimensions will be tested. For example, experiments addressing increased spot elongation, cone effect and the order of correction required. A pan-European consortium proposes to construct test facility infrastructure on the WHT for a number of risk mitigating experiments. The infrastructure includes the construction of a Nasmyth platform based controlled environment 'Ground-based Adaptive optics Innovative Laboratory' (GRAIL), an experimental test environment 'Testbed integration facility' (TIF) and some common-experiment equipment such as the Common Re-Imaging AO System. Experiments that are proposed for this facility cover the areas of laser technologies, spot elongation, LGS wavefront sensing, parallel launch concepts, Multi-Object AO, atmospheric characterisation, co-phasing and real-time control system risk mitigation.

The Polychromatic Laser Guide Star aims at providing for the tilt measurement from a LGS without any natural guide star. Thus it allows adaptive optics to provide us with a full sky coverage. This is critical in particular to extend adaptive optics to the visible range, where isoplanatism is so small that the probability is negligible to find a natural star to measure the tilt. We report new results obtained within the framework of the Polychromatic LGS programme ELP-OA. Natural stars have been used to mimic the PLGS, in order to check the feasibility of using the difference in the tilt at two wavelengths to derive the tilt itself. We report results from the ATTILA experiment obtained at the 1.52 m telescope at Observatoire de Haute-Provence. Tilts derived from the differential tilts are compared with direct tilt measurements. The accuracy of the measurements is currently ≈ 1.5 Airy disk rms at 550 nm. These results prove the feasibility of the Polychromatic Laser Guide Star programme ELP-OA. New algorithms based on inverse problems under development within our programme would lead to smaller error bars by 1 magnitude, as soon as they will run fast enough. We describe the ELP-OA demonstrator which we are setting up at the same telescope, with a special emphasis on the optimization of the excitation process, which definitely has to rely on the two-photon excitation of sodium atoms in the mesosphere. We will describe the implementation at the telescope, including the projector device, the focal instrumentation and the NdYAG pumped dye lasers.

The Shack-Hartmann wavefront sensor is composed of a lenslet array generating the spot images from which local slope is calculated and overall wavefront is measured. Generally the principle of wavefront reconstruction is that the spot centroid of each lenslet array is calculated from pixel intensity values in its subaperture and then overall wavefront is reconstructed by local slope of wavefront obtained by deviations from reference positions. Hence the spot image of each lenslet array has to remain in its subaperture for exact measurement of wavefront. However the spot of each lenslet array deviates from its subaperture area when wavefront with large local slopes enters the Shack-Hartmann sensor. In this research, we propose the spot image searching method that finds area of each measured spot image flexibly and determine the centroid of each spot in its area. Also the algorithms that match these centroids to their reference points unequivocally even if some of them are situated off the allocated subaperture are proposed. Finally we verify the proposed algorithm with the test of a defocus measurement through experimental setup for the Shack-Hartmann wavefront sensor. It has been shown that the proposed algorithm can expand the dynamic range without additional devices.

This paper deals with evaluation and processing of astronomical image data, which are obtained by WFC (Wide-Field Camera) or UWFC (Ultra Wide-Field Camera) systems. Precision of astronomical image data post-processing and analyzing is very important. Large amount of different kinds of optical aberrations and distortions is included in these systems. The amplitude of wavefront aberration error increases towards margins of the FOV (Field of View). Relation between amount of high order optical aberrations and astrometry measurement precision is discussed in this paper. There are descriptions of the transfer characteristics of astronomical optical systems presented in this paper. Spatially variant (SV) optical aberrations negatively affect the transfer characteristics of all system and make it spatially variant as well. SV model of optical system is presented in this paper. Partially invariant model of optical systems allows using Fourier methods for deconvolution. Some deconvolution results are shown in this paper.

We report on the current status of production of the thin shells for the LBT adaptive secondary mirrors. These shells are made of Zerodur and have a front (optical) surface highly aspherical whereas the other (rear) surface is spherical. They have a 910mm diameter and an average thickness of 1.6mm. The manufacturing of these shells starts with a thick blank of Zerodur and follows the steps of: 1) optical surface figuring, 2) blank thinning, 3) rear surface grinding and polishing, 4) edges machining and 5) rear surface aluminizing. Of the three (two plus a spare) shells planned for LBT the first shell was completed and shipped to Italy for integration with magnets and the second is in advanced state of production. The third shell (spare) is planned to start production soon. In the paper we report details of production of these shells as well as the 'as built' characteristics. Details concerning the operations that follow the production, i.e. surface aluminum coating as well as handling and shipping fixtures are also reported.