Status update for MAPS, the MMT AO exoPlanet characterization System

MAPS, MMT Adaptive optics exoPlanet characterization System, is the upgrade of legacy 6.5m MMT adaptive optics system. It is an NSF MSIP-funded project that includes (i) refurbishing of the MMT Adaptive Secondary Mirror (ASM), (ii) new high sensitive and high spatial order visible and near-infrared pyramid wavefront sensors, and (iii) the upgrade of Arizona Infrared Imager and Echelle Spectrograph (ARIES) and MMT high Precision Imaging Polarimeter (MMTPol) science cameras. This paper will present the design and development of the visible pyramid wavefront sensor. This system consists of an acquisition camera, a fast-steering tip-tilt modulation mirror, a double pyramid, a pupil imaging triplet lens, and a low noise and high-speed frame rate based CCID75 camera. We will report on hardware and software and present the laboratory characterization results of the individual subsystems, and outline the on-sky commissioning plan.

We present laboratory results of the closed-loop performance of the Magellan\nAdaptive Optics (AO) Adaptive Secondary Mirror (ASM), pyramid wavefront sensor\n(PWFS), and VisAO visible adaptive optics camera. The Magellan AO system is a\n585-actuator low-emissivity high-throughput system scheduled for first light on\nthe 6.5 meter Magellan Clay telescope in November 2012. Using a dichroic\nbeamsplitter near the telescope focal plane, the AO system will be able to\nsimultaneously perform visible (500-1000 nm) AO science with our VisAO camera\nand either 10 micron or 3-5 micron science using either the BLINC/MIRAC4 or\nCLIO cameras, respectively. The ASM, PWS, and VisAO camera have undergone final\nsystem tests in the solar test tower at the Arcetri Institute in Florence,\nItaly, reaching Strehls of 37% in i'-band with 400 modes and simulated\nturbulence of 14 cm ro at v-band. We present images and test results of the\nassembled VisAO system, which includes our prototype advanced Atmospheric\nDispersion Corrector (ADC), prototype calcite Wollaston prisms for SDI imaging,\nand a suite of beamsplitters, filters, and other optics. Our advanced ADC\nperforms in the lab as designed and is a 58% improvement over conventional ADC\ndesigns. We also present images and results of our unique Calibration Return\nOptic (CRO) test system and the ASM, which has successfully run in closed- loop\nat 1kHz. The CRO test is a retro reflecting optical test that allows us to test\nthe ASM off-sky in close-loop using an artificial star formed by a fiber\nsource.\n

We are upgrading and refurbishing the first-generation adaptive-secondary mirror (ASM)-based AO system on the 6.5-m MMT in Arizona, in an NSF MSIP-funded program that will create a unique facility specialized for exoplanet characterization. This update includes a third-generation ASM with embedded electronics for low power consumption, two pyramid wavefront sensors (optical and near-IR), and an upgraded ARIES science camera for high-resolution spectroscopy (HRS) from 1-5 µm and MMT-POL science camera for sensitive polarization mapping. Digital electronics have been incorporated into each of the 336 actuators, simplifying hub-level electronics and reducing the total power to 300 W, down from 1800 W in the legacy system-reducing cooling requirements from active coolant to passive ambient cooling. An improved internal control law allows for electronic damping and a faster response. The dual pyramid wavefront sensors allow for a choice between optical or IR wavefront sensing depending on guide star magnitude, color, and extinction. The HRS upgrade to ARIES enables crosscorrelation of molecular templates to extract atmospheric parameters of exoplanets. The combination of these upgrades creates a workhorse instrument for exoplanet characterization via AO and HRS to separate planets from their host stars, with broad wavelength coverage and polarization to probe a range of molecular species in exoplanet atmospheres. © 2020 SPIE.

The next generation of giant ground and space telescopes will have the light-collecting power to detect and characterize potentially habitable terrestrial exoplanets using high-contrast imaging for the first time. This will only be achievable if the performance of the Giant Segment Mirror Telescopes (GSMTs) extreme adaptive optics (ExAO) systems are optimized to their full potential. A key component of an ExAO system is the wavefront sensor (WFS), which measures aberrations from atmospheric turbulence. A common choice in current and next-generation instruments is the pyramid wavefront sensor (PWFS). ExAO systems require high spatial and temporal sampling of wavefronts to optimize performance and, as a result, require large detectors for the WFS. We present a closed-loop testbed demonstration of a three-sided pyramid wavefront sensor (3PWFS) as an alternative to the conventional four-sided pyramid wavefront (4PWFS) sensor for GSMT-ExAO applications on the innovative comprehensive adaptive optics and coronagraph test instrument (CACTI). The 3PWFS is less sensitive to read noise than the 4PWFS because it uses fewer detector pixels. The 3PWFS has further benefits: a high-quality three-sided pyramid optic is easier to manufacture than a four-sided pyramid. We describe the design of the two components of the CACTI system, the adaptive optics simulator and the PWFS testbed that includes both a 3PWFS and 4PWFS. We detail the error budget of the CACTI system, review its operation and calibration procedures, and discuss its current status. A preliminary experiment was performed on CACTI to study the performance of the 3PWFS to the 4PWFS in varying strengths of turbulence using both the raw intensity and slopes map signal processing methods. This experiment was repeated for a modulation radius of 1.6 and 3.25 λ / D. We found that the performance of the two wavefront sensors is comparable if modal loop gains are tuned.

Several telescopes include large Deformable Mirrors (DM) located directly inside the telescope. These adaptive telescopes trigger new constraints for the calibration of the Adaptive Optics (AO) systems as they usually offer no access to an artificial calibration source for the interaction matrix measurement. Moreover, the optical propagation between the DM and the Wave-Front Sensor (WFS) may evolve during the operation, resulting in mis-registrations that highly affect the AO performance and thus the scientific observation. They have to be measured and compensated, for instance by updating the calibration. A new strategy consists of estimating the mis-registrations and injecting them into synthetic models to generate noise-free interaction matrices. This pseudo-synthetic approach is the baseline for the Adaptive Optics Facility working with a Shack-Hartmann WFS and seems particularly suited for the future Extremely Large Telescope as the calibration will have to be regularly updated, for a large numbers of actuators. In this paper, the feasibility of a pseudo synthetic calibration with Pyramid WFS at the Large Binocular Telescope (LBT) is investigated. A synthetic model of the LBT AO systems is developed, and the procedure to adjust the mis-registrations parameters is introduced, extracting them from an experimental interaction matrix. We successfully tested an interaction matrix generated from the model on the real system in high-order AO mode. We recorded a slightly better performance with respect to the experimental one. This work demonstrates that a high accuracy calibration can be obtained using the pseudo synthetic approach with pyramid WFS.

Notes on Contributors

This is a time that poses numerous challenges to urban geographers and the cities they study. As it happens, 2004 was a period of disciplinary reflection marking the centennial of the Association of American Geographers (AAG). As graduate student members of the board of the AAG’s Urban Geography Specialty Group, we capitalized on a confluence of events to organize a panel entitled “The state of urban geography: What is it and where is it going?” for the AAG’s 2004 annual meeting in Philadelphia. This year of disciplinary celebration also coincided with the torment of our own early professional lives as newly-minted, so-called urban geographers. Drawn into collaboration through these circumstances, we chose to organize a session in which we invited urban geographers at various stages in their careers to reflect on the subdiscipline and its practice. To initiate dialogue, we asked: What is the significance of the subdiscipline to the production and application of geographic knowledge? What—or who—defines urban geography? Is urban geography what urban geographers do or is it something more? To be sure, the forward-looking spirit of the day fulfilled our initial hopes. We were fortunate to assemble an impressive set of urban geographers with diverse interests and experiences, including Larry Bourne (University of Toronto), Winifred Curran (DePaul University), Michael Dear (University of Southern California), Sarah Elwood (University of Arizona), Robert Lake (Rutgers University), and Sallie Marston (University of Arizona). Some panelists were close to retirement and others were equally close to the start of a new job. The group spoke to a standing-room-only crowd about their accomplishments, their hopes for, and their disappointments with urban geography at the turn of the millennium. When invited to assemble and introduce the panelists’ reflections as a symposium for this journal, we relished our own opportunity to ponder the state of the subdiscipline. But

The paper deals with with the on-sky performance of the pyramid wavefront sensor-based Adaptive Optics (AO) systems. These wavefront sensors are of great importance, being used in all first light AO systems of the ELTs (E-ELT, GMT, and TMT), currently in design phase. In particular, non-common path aberrations (NCPAs) are a critical issue encountered when using an AO system to produce corrected images in an associated astronomical instrument. The AO wavefront sensor (WFS) and the supported scientific instrument typically use a series of different optical elements, thus experiencing different aberrations. The usual way to correct for such NCPAs is to introduce a static offset in the WFS signals. In this way, when the AO loop is closed the sensor offsets are zeroed and the deformable mirror converges to the shape required to null the NCPA. The method assumes that the WFS operation is linear and completely described by some pre-calibrated interaction matrix. This is not the case for some frequently used wavefront sensors like the Pyramid sensor or a quad-cell Shack-Hartmann sensor. Here we present a method to work in closed-loop with a pyramid wavefront sensor, or more generally a non-linear WFS, introducing a wavefront offset that remains stable when AO correction quality changes due to variations in external conditions like star brightness, seeing, and wind speed. The paper details the methods with analytical and numerical considerations. Then we present results of tests executed at the LBT telescope, in daytime and on sky, using the FLAO system and LUCI2 facility instrument. The on-sky results clearly show the successful operation of the method that completely nulls NCPA, recovering diffraction-limited images with about 70% Strehl ratio in H band in variable seeing conditions. The proposed method is suitable for application to the above-mentioned ELT AO systems.

The European Extremely Large Telescope (ELT) is a 39m large, ground-based optical and near- to mid-infrared telescope under construction in the Chilean Atacama desert. Operation is planned to start around the middle of the next decade. All first light instruments will come with wavefront sensing devices that allow control of the ELT’s intrinsic M4 and M5 wavefront correction units, thus building an adaptive optics (AO) system. To take advantage of the ELT’s optical performance, full diffraction-limited operation is required and only a high performance AO system can deliver this. Further technically challenging requirements for the AO come from the exoplanet research field, where the task to resolve the very small angular separations between host star and planet, has also to take into account the high-contrast ratio between the two objects. We present in detail the results of our simulations and their impact on high-contrast imaging in order to find the optimal wavefront sensing device for the METIS instrument. METIS is the mid-infrared imager and spectrograph for the ELT with specialised high-contrast, coronagraphic imaging capabilities, whose performance strongly depends on the AO residual wavefront errors. We examined the sky and target sample coverage of a generic wavefront sensor in two spectral regimes, visible and near-infrared, to pre-select the spectral range for the more detailed wavefront sensor type analysis. We find that the near-infrared regime is the most suitable for METIS. We then analysed the performance of Shack-Hartmann and pyramid wavefront sensors under realistic conditions at the ELT, did a balancing with our scientific requirements, and concluded that a pyramid wavefront sensor is the best choice for METIS. For this choice we additionally examined the impact of non-common path aberrations, of vibrations, and the long-term stability of the SCAO system including high-contrast imaging performance.

A Spatially Adjusted ANOVA Model

Context. Direct detection of exoplanets around nearby stars requires advanced adaptive optics (AO) systems. High-order systems are needed to reach a high Strehl ratio (SR) in near-infrared and optical wavelengths on future giant segmented-mirror telescopes (GSMTs). Direct detection of faint exoplanets with the European Southern Observatory (ESO) Extremely Large Telescope (ELT) will require some tens of thousands of correction modes. The resolution and sensitivity of the wavefront sensor (WFS) are key requirements for this science case. We present a new class of WFSs, the bi-orthogonal Foucault knife-edge sensors (or Bi–O edge), that is directly inspired by the Foucault knife-edge test. The idea consists of using a beam-splitter producing two foci, each of which is sensed by an edge with a direction orthogonal to the other focus.Aims. We describe two implementation concepts: The Bi–O edge sensor can be realised with a sharp edge and a tip-tilt modulation device (sharp Bi–O edge) or with a smooth gradual transmission over a grey edge (grey Bi–O edge). A comparison of the Bi–O edge concepts and the four-sided classical pyramid wavefront sensor (PWS) gives some important insights into the nature of the measurements.Methods. We analytically computed the photon noise error propagation, and we compared the results to end-to-end simulations of a closed-loop AO system.Results. Our analysis shows that the sensitivity gain of the Bi–O edge with respect to the PWS depends on the system configuration. The gain is a function of the number of control modes and the modulation angle. We found that for the sharp Bi–O edge, the gain in reduction of propagated photon noise variance approaches a theoretical factor of 2 for a large number of control modes and small modulation angle, meaning that the sharp Bi–O edge only needs half of the photons of the PWS to reach similar measurement accuracy. In contrast, the PWS is twice more sensitive than the Bi–O edge in the case of very low order correction and/or large modulation angles. Preliminary end-to-end simulations illustrate some of the results. The grey version of the Bi–O edge opens the door to advanced amplitude filtering, which replaces the need for a tip-tilt modulator while keeping the same dynamic range. We show that an additional factor of 2 in reduction of propagated photon noise variance can be obtained for high orders, such that the theoretical maximum gain of a factor of 4 in photon efficiency can be obtained. A diffractive Fourier model that accurately includes the effect of modulation and control modes shows that for the extreme AO (XAO) system configuration of the ELT, the overall gain will well exceed one magnitude in guide-star brightness when compared to the modulated PWS.Conclusions. We conclude that the Bi–O edge is an excellent candidate sensor for future very high order Adaptive Optics systems, in particular on GSMTs.

A pyramid wavefront sensor (PWFS) bench has been setup at NRC-Herzberg (Victoria, Canada) to investigate, first, the feasibility of a double roof prism PWFS, and second, test the proposed pyramid wavefront sensing methodology to be used in NFIRAOS for the Thirty Meter Telescope. Traditional PWFS require shallow angles and strict apex tolerances, making them difficult to manufacture. Roof prisms, on the other hand, are common optical components and can easily be made to the desired specifications. Understanding the differences between a double roof prism PWFS and traditional PWFS will allow for the double roof prism PWFS to become more widely used as an alternative to the standard pyramid, especially in a laboratory setting. In this work, the response of the double roof prism PWFS as the amount of modulation is changed, is compared to an ideal PWFS modelled using the adaptive optics toolbox, OOMAO in MATLAB. The object oriented toolbox uses physical optics to model complete AO systems. Fast modulation and dithering using a PI mirror has been implemented using a micro-controller to drive the mirror and trigger the camera. The various trade offs of this scheme, in a controlled laboratory environment, are studied and reported.

ABSTRACTAdaptive optics will almost completely remove the effects of atmospheric turbulence at 10 μm on the Extremely Large Telescope (ELT) generation of telescopes. In this article, we observationally confirm that the next most important limitation to image quality is atmospheric dispersion, rather than telescope diffraction. By using the 6.5 m MMT with its unique mid-IR adaptive optics system, we measure atmospheric dispersion in the N band with the newly commissioned spectroscopic mode on MIRAC4-BLINC. Our results indicate that atmospheric dispersion is generally linear in the N band, although there is some residual curvature. We compare our measurements to theory, and make predictions for ELT Strehls and image FHWM with and without an atmospheric dispersion corrector (ADC). We find that for many mid-IR applications, an ADC will be necessary on ELTs.

Context.The direct imaging of potentially habitable exoplanets is one prime science case for the next generation of high contrast imaging instruments on ground-based, extremely large telescopes. To reach this demanding science goal, the instruments are equipped with eXtreme Adaptive Optics (XAO) systems which will control thousands of actuators at a framerate of kilohertz to several kilohertz. Most of the habitable exoplanets are located at small angular separations from their host stars, where the current control laws of XAO systems leave strong residuals.Aims.Current AO control strategies such as static matrix-based wavefront reconstruction and integrator control suffer from a temporal delay error and are sensitive to mis-registration, that is, to dynamic variations of the control system geometry. We aim to produce control methods that cope with these limitations, provide a significantly improved AO correction, and, therefore, reduce the residual flux in the coronagraphic point spread function (PSF).Methods.We extend previous work in reinforcement learning for AO. The improved method, called the Policy Optimization for Adaptive Optics (PO4AO), learns a dynamics model and optimizes a control neural network, called a policy. We introduce the method and study it through numerical simulations of XAO with Pyramid wavefront sensor (PWFS) for the 8-m and 40-m telescope aperture cases. We further implemented PO4AO and carried out experiments in a laboratory environment using Magellan Adaptive Optics eXtreme system (MagAO-X) at the Steward laboratory.Results.PO4AO provides the desired performance by improving the coronagraphic contrast in numerical simulations by factors of 3–5 within the control region of deformable mirror and PWFS, both in simulation and in the laboratory. The presented method is also quick to train, that is, on timescales of typically 5–10 s, and the inference time is sufficiently small (<ms) to be used in real-time control for XAO with currently available hardware even for extremely large telescopes.

Dissertation List Jonathan Erlen and Jay Toth January 2006 Ackley, Kristina Lyn. "We are Oneida yet: Discourse in the Oneida land claim." PhD diss., SUNY at Buffalo, 2005. Alessi, Joseph P. "Settling America: Indians, Euroamericans, and the establishment of the frontier towns, 1600-1830." PhD diss., St. Louis University, 2005. Atine, Christine D. "The experience of Navajo families living with the stigma of mental illness: A phenomenological study." PhD diss., University of Denver, 2005. Davis, James Joe, Jr. "The effects of coalition building on Public Law 93-531: The Navajo and Hopi Land Settlement Act of 1974." PhD diss., University of Arizona, 2005. De Leon, Diana Fisher. "A study on forging a new front and building a new vision for tribal environmental health policy on the Colorado River Indian Reservation." PhD diss., University of Arizona, 2005. Denial, Catherine Jane. "A proper light before the country: The shifting politics of gender and kinship among the Dakota, Ojibwe and non-Native communities of the Upper Midwest, 1825-1845." PhD diss., University of Iowa, 2005. Evans, Lara M. "One of these things is not like the other: Works by Native performance artists James Luna, Greg Hill, and Rebecca Bemore." PhD diss., University of New Mexico, 2005. Fitzgerald, Barbara J. "Gender equity and technology use in K-5 classrooms in a Native American school." PhD diss., Walden University, 2005. Funk, Caroline L. "Evolutionary and cognitive influences on hunter-gatherer settlement location in the Yukon-Kuskokwim Delta of Alaska." PhD diss., University of Wisconsin, 2005. [End Page 549] George, Maggie L. "The promise of indigenous education: A case study of Navajo bilingual-bicultural teachers." PhD diss., University of Kansas, 2005. Green, Chris. "The epidemiology of diabetes in Manitoba: An exploration through time and space." PhD diss., University of Manitoba, 2005. Kipp, Billie Jo. "Crystallized versus fluid intelligence in American Indian children referred to developmental clinics: An examination of multiple measures and indicators." PhD diss., University of Montana, 2005. Krahe, Diane L. "Last refuge: The uneasy embrace of Indian lands by the national wilderness movement, 1937-1965." PhD diss., Washington State University, 2005. Labreche, Yves. "Appropriation et conservation des resources alimentaires chez les Inuit de Kangiqsujuaq-Salliuit, Québec arctique: Perspective ethnoarchéologique." PhD diss., Université de Montréal, 2005. Lambe, Jeffrey P. "We plant a tree of peace: Mohawk Chief Jake Swamp's narratives, dynamics of relationships, and principles of peace." PhD diss., Trent University, 2005. Lang, Martin Joeseph. "Conspicuous absence, quiet presence: Representations of American Indians and gaming in Minnesota's mainstream and Indian-produced newspapers." PhD diss., University of Minnesota, 2005. Larcombe, Linda Anne. "Native North American resistance and susceptibility to infectious diseases: An anthropological approach." PhD diss., University of Manitoba, 2005. Manuelito-Kervliet, Cassandra. "Widening the circle: Mentoring and the learning process for American Indian women in tribal college administration." PhD diss., University of Oregon, 2005. McGlennen, Molly Suzanne. "It is evidence of faith to create: Spirituality and contemporary Native American women's poetics." PhD diss., University of California, 2005. Milligan, Marianne I. "Menominee prosodic structure." PhD diss., University of Wisconsin, 2005. Pauli, Wayne E. "The Native American digital divide: A preliminary investigation of an undergraduate population in South Dakota." PhD diss., Capella University, 2005. Powell, Francis J. "Assessing the identity of black Indians in Louisiana: A quantitative and qualitative analysis." PhD diss., Louisiana State University and Agricultural and Mechanical College, 2004. Ramos, Frances Lourdes. "The politics of ritual in Puebla de los Angeles, Mexico, 1695-1775." PhD diss., University of Texas, 2005. Robertson, Carmen Lee. "Reel artists: National Film Board of Canada portrayals of contemporary Aboriginal and Inuit artists and their art." PhD diss., University of Calgary, 2005. [End Page 550] Stock, Karen S. E. "The Skownan First Nation model for sustainable development and Aboriginal stewardship." PhD diss., University of Manitoba, 2005. Tronsen, Beverly Kay. "The rhetoric of disappearances: Racialized discourse and the Cherokee Removal." PhD diss., Washington State University, 2005. Vermilion, Mary R. "The Loyd site (11 MS 74): A prehistoric Moorehead phase nodal site." PhD diss., University of Illinois, 2005. Wilmerding, Mary Elizabeth Gesek. "The cultural sequence at the Nunik site, Chernabura Island, Alaska." PhD diss., Washington State University, 2005. February 2006 Andersen, Christian. "Courting colonialism? The juridical construction...