Tomographic reconstruction using multiple laser guide stars (MLGS) will be required by the next generation of extremely large (30 m class) telescopes (ELT). Modal decomposition of wavefront phase using Zernike polynomials is a widely used technique in adaptive optics (AO) research. However, this approach breaks down with the large number of degrees of freedom required by ELTs.This research proposes the use of an alternative basis, the disk harmonic functions, to overcome the disadvantages of the Zernike basis at high spatial resolution. A method of fast, analytic, modal tomographic modeling is developed and used for fast calculation of reconstruction matrices used on-sky at the MMT telescope.The specific reconstruction techniques of ground layer adaptive optics and laser tomography adaptive optics using MLGS are presented along with the results of on-sky experiments at the MMT. In addition to developing a laser AO instrument for the MMT, these experiments provide a test bed for validating the reconstruction techniques that will be critical to the success of ELTs.An approach to using real-time wavefront sensor and deformable mirror telemetry from the MLGS system to estimate the vertical distribution of turbulence in the atmosphere is also presented.

We present the results of a survey of 45 young (<250>Myr), close (<50>pc) stars with the Simultaneous Differential Imager (SDI) implemented at the VLT and the MMT for the direct detection of extrasolar planets. Our SDI devices use a double Wollaston prism and a quad filter to take images simultaneously at three wavelengths surrounding the 1.62 um methane absorption bandhead found in the spectrum of cool brown dwarfs and extrasolar giant planets. By performing a difference of adaptive optics corrected images in these filters, speckle noise from the primary star can be significantly attenuated, resulting in photon (and flat-field) noise limited data. In our VLT data, we achieved H band contrasts > 10 mag (5 sigma) at a separation of 0.5" from the primary star on 45% of our targets and H band contrasts of > 9 mag at a separation of 0.5'' on 80% of our targets. With this degree of attenuation, we should be able to image (5 sigma detection) a 7 MJup planet 15 AU from a 70 Myr K1 star at 15 pc or a 7.8 MJup planet at 2 AU from a 12 Myr M star at 10 pc. Using the capabilities of the unique SDI device, we also discovered a methane-rich substellar companion to SCR 1845-6357 (a recently discovered (Hambly et al., 2004) M8.5 star just 3.85 pc from the Sun (Henry et al., 2006) at a separation of 4.5 AU (1.170''+-0.003'' on the sky) and fainter by 3.57$\pm$0.057 mag in the 1.575 um SDI filter.We also present high resolution (~0.1''), very high Strehl ratio (0.97+-0.03) mid-infrared (IR) adaptive optics (AO) images of the AGB star RV Boo utilizing the MMT adaptive secondary AO system. RV Boo was observed at a number of wavelengths over two epochs and appeared slightly extended at all wavelengths. With such high Strehls we can achieve super-resolutions of 0.1'' by deconvolving RV Boo with a point-spread function (PSF) derived from an unresolved star.SDI on ground based telescopes provides significant speckle attenuations down to star-planet contrasts of ~1-3x10^4. To test the classical SDI technique at contrasts of 10^6-9, we implemented a similar multiwavelength differential imaging scheme for the JPL High Contrast Imaging Testbed.

This dissertation outlines the development of static and dynamic tomographic wave-front (WF) reconstructors tailored to Multi-Object Adaptive Optics (MOAO). They are applied to Raven, the first MOAO science and technology demonstrator recently installed on an 8m telescope, with the goal of increasing the limiting magnitude in order to increase sky coverage. The results of a new minimum mean-square error (MMSE) solution based on spatio-angular (SA) correlation functions are shown, which adopts a zonal representation of the wave-front and its associated signals. This solution is outlined for the static reconstructor and then extended for the use of standalone temporal prediction. Furthermore, it is implemented as the prediction model in a pupil plane based Linear Quadratic Gaussian (LQG) algorithm. The algorithms have been fully tested in the laboratory and compared to the results from Monte- Carlo simulations of the Raven system. The simulations indicate that an increase in limiting magnitude of up to one magnitude can be expected when prediction is implemented. Two or more magnitudes of improvement may be achievable when the LQG is used. These results are confirmed by laboratory measurements. / Graduate

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In this dissertation I present the results from five papers (including one in preparation) on giant planets, brown dwarfs, and their environments, as well as on the commissioning and optimization of the Adaptive Optics system for the Large Binocular Telescope Interferometer. The first three Chapters cover direct imaging results on several distantly-orbiting planets and brown dwarf companions. The boundary between giant planets and brown dwarf companions in wide orbits is a blurry one. In Chapter 2, I use 3–5 μm imaging of several brown dwarf companions, combined with mid-infrared photometry for each system to constrain the circum-substellar disks around the brown dwarfs. I then use this information to discuss limits on scattering events versus in situ formation. In Chapters 3 and 4, I present results from an adaptive optics imaging survey for giant planets, where the target stars were selected based on the properties of their circumstellar debris disks. Specifically, we targeted systems with debris disks whose SEDs indicated gaps, clearings, or truncations; these features may possibly be sculpted by planets. I discuss in detail one planet-mass companion discovered as part of this survey, HD 106906 b. At a projected separation of 650 AU and weighing in at 11 Jupiter masses, a companion such as this is not a common outcome of any planet or binary star formation model. In the remaining three Chapters, I discuss pre-commissioning, on-sky results, and planned work on the Large Binocular Telescope Interferometer Adaptive Optics system. Before construction of the LBT AO system was complete, I tested a prototype of LBTI's pyramid wavefront sensor unit at the MMT with synthetically-generated calibration files. I present the methodology and MMT on-sky tests in Chapter 5. In Chapter 6, I present the commissioned performance of LBTIAO. Optical imperfections within LBTI limited the quality of the science images, and I describe a simple method to use the adaptive optics system to correct for the science camera's optical aberrations. Finally, in Chapter 7, I discuss the status of a more sophisticated method for correcting these optical aberrations in LBTI.

Adaptive optics holds a fundamental role in the era of thirty meter class telescopes; this technology has gained such import that is incorporated into all first light instruments of both the upcoming E-ELT and TMT telescopes. Moreover, each of these telescopes are planning to use advanced forms of adaptive optics to exploit unprecedented scientific niches, such as Multi-Conjugate Adaptive Optics and Multi-Object Adaptive Optics. The complexity of these systems requires careful preliminary considerations, such as demonstration of the technology on existing telescopes and effective calibration procedures. In this thesis I address these two considerations through two different approaches. First, I demonstrate the use of the Multi-Object Adaptive Op- tics demonstrator RAVEN to gather high-resolution spectroscopy for the first time with this technology, and I identify some of the most metal-poor stars in the Galactic bulge to date. Secondly, I develop two focal plane wavefront sensing techniques to calibrate the internal aberrations of RAVEN and explore their applications to other adaptive optics systems.  I analyze spectra of individual stars in two Globular Clusters to establish infrared techniques that can be used with the RAVEN instrument. Detailed chemical abundances for five stars in NGC 5466 and NGC 5024, are presented from high-resolution optical (from the Hobby-Eberley Telescope) and infrared spectra (from the SDSS- III APOGEE survey). I find [Fe/H] = -1.97 ± 0.13 dex for NGC 5466, and [Fe/H] = -2.06 ± 0.13 dex for NGC 5024, and the typical abundance pattern for globular clusters for the remaining elements, e.g. both show evidence for mixing in their light element abundance ratios (C, N), and asymptotic giant branch contributions in their heavy element abundances (Y, Ba, and Eu). These clusters were selected to examine chemical trends that may correlate them with the Sgr dwarf galaxy remnant, but at these low metallicities no obvious differences from the Galactic abundance pattern are found. Regardless, I compare my results from the optical and infrared analyses to find that oxygen and silicon abundances determined from the infrared spectral lines are in better agreement with the other α-element ratios and with smaller random errors. Using the aforementioned infrared techniques, I derive the chemical abundances for five metal-poor stars in and towards the Galactic bulge from the H-band spectroscopy taken with RAVEN at the Subaru 8.2-m telescope. Three of these stars are in the Galactic bulge and have metallicities between -2.1 < [Fe/H] < -1.5, and high [α/Fe] ∼ +0.3, typical of Galactic disc and bulge stars in this metallicity range; [Al/Fe] and [N/Fe] are also high, whereas [C/Fe] < +0.3. An examination of their orbits suggests that two of these stars may be confined to the Galactic bulge and one is a halo trespasser, though proper motion values used to calculate orbits are quite uncertain. An additional two stars in the globular cluster M22 show [Fe/H] values consistent to within 1σ , although one of these two stars has [Fe/H] = -2.01 ± 0.09, which is on the low end for this cluster. The [α/Fe] and [Ni/Fe] values differ by 2, with the most metal-poor star showing significantly higher values for these elements. M22 is known to show element abundance variations, consistent with a multipopulation scenario though our results cannot discriminate this clearly given our abundance uncertainties. This is the first science demonstration of multi-object adaptive optics with high-resolution infrared spectroscopy, and we also discuss the feasibility of this technique for use in the upcoming era of 30-m class telescope facilities. Lastly, I develop two focal plane wavefront sensing techniques to calibrate the non-common path aberrations (NCPA) in adaptive optics systems. I first demonstrate these techniques in a detailed simulation of the future TMT instrument NFIRAOS. I then validate these techniques on an experimental bench subject to NFIRAOS-like wavefront errors. The two techniques are subsequently used to identify and correct the NCPA on both RAVEN and the NFIRAOS test-bench knowns as HeNOS. The application of these techniques is also explored on the VLT/SPHERE system to identify what is known as the ‘Low Wind Effect’ (LWE). I first quantify the LWE in simulation and then validate the technique on an experimental bench. I then estimate the LWE from on-sky data taken with the VLT/SPHERE adaptive optics system. Lastly, I apply my focal plane wavefront sensing techniques to estimate residual mirror co-phasing errors seen on Keck with the NIRC2 adaptive optics system data. I first demonstrate the ability of my techniques to quantify these errors in a simulation of Keck/NIRC2 data. I then apply their capabilities to estimate the mirror co-phasing errors of Keck with on-sky data. / Graduate

No description available.

The Large Binocular Telescope Interferometer (LBTI) is a high spatial resolution instrument developed for coherent imaging and nulling interferometry using the 14.4 m baseline of the 2x8.4 m LBT. The unique telescope design, comprising of the dual apertures on a common elevation-azimuth mount, enables a broad use of observing modes. The full system is comprised of dual adaptive optics systems, a near-infrared phasing camera, a 1-5 mu m camera (called LMIRCam), and an 8-13 mu m camera (called NOMIC). The key program for LBTI is the Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS), a survey using nulling interferometry to constrain the typical brightness from exozodiacal dust around nearby stars. Additional observations focus on the detection and characterization of giant planets in the thermal infrared, high spatial resolution imaging of complex scenes such as Jupiter's moon, Io, planets forming in transition disks, and the structure of active Galactic Nuclei (AGN). Several instrumental upgrades are currently underway to improve and expand the capabilities of LBTI. These include: Improving the performance and limiting magnitude of the parallel adaptive optics systems; quadrupling the field of view of LMIRcam (increasing to 20"x20"); adding an integral field spectrometry mode; and implementing a new algorithm for path length correction that accounts for dispersion due to atmospheric water vapor. We present the current architecture and performance of LBTI, as well as an overview of the upgrades.

In the field of exoplanetary sciences, high contrast imaging is crucial for the direct detection of, and answering questions about habitability of exoplanets. For the direct imaging of habitable exoplanets, it is important to employ low inner working angle (IWA) coronagraphs, which can image exoplanets close to the PSF. To achieve the full performance of such coronagraphs, it is crucial to correct for atmospheric dispersion to the highest degree, as any leakage will limit the contrast. To achieve the highest contrast with the state-of-the-art coronagraphs in the SCExAO instrument, the spread in the point-spread function due to residual atmospheric dispersion should not be more than 1 mas in the science band. In a traditional approach, atmospheric dispersion is compensated by an atmospheric dispersion compensator (ADC), which is simply based on model which only takes into account the elevation of telescope and hence results in imperfect correction of dispersion. In this paper we present the first on-sky closed-loop measurement and correction of residual atmospheric dispersion. Exploiting the elongated nature of chromatic speckles, we can precisely measure the presence of atmospheric dispersion and by driving the ADC, we can do real-time correction. With the above approach, in broadband operation (y-H band) we achieved a residual of 4.2 mas from an initial 18.8 mas and as low as 1.4 mas in H-band only after correction, which is close to our science requirement. This work will be valuable in the field of high contrast imaging of habitable exoplanets in the era of the ELTs.

Traditionally, adaptive optics (AO) systems for microscopy have focused on AO at the pupil plane, however this produces poor performance in samples with both spatially-variant aberrations, such as non-flat sample interfaces, and spatially-invariant aberrations, such as spherical aberration due to a difference between the sample index of refraction and the sample for which the objective was designed. Here, we demonstrate well-corrected, wide field-of-view (FOV) microscopy by simultaneously correcting the two types of aberrations using two AO loops. Such an approach is necessary in wide-field applications where both types of aberration may be present, as each AO loop can only fully correct one type of aberration. Wide FOV corrections are demonstrated in a trans-illumination microscope equipped with two deformable mirrors (DMs), using a partitioned aperture wavefront (PAW) sensor to directly control the DM conjugated to the sample interface and a sensor-less genetic algorithm to control the DM conjugated to the objective’s pupil.