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8 results on '"Kenworthy, M."'

1. Implications for contrast as a result of the wind vector and non-stationary turbulence

Author

Kooten, M.A.M. van, Doelman, N.J., and Kenworthy, M.

Subjects
Optical telescopes, Thirty Meter Telescope, Non-stationary behavior, Industrial Innovation, Wavefronts, Errors, High contrast, Atmospheric turbulence, AO control, High Tech Systems & Materials, Wind effects, Power spectral densities (PSD), Spectral density, Wind speed time series, Wind modeling, Non-stationary turbulence, Adaptive optics systems, Electronics, Adaptive optics, Time delay
Abstract

In an adaptive optics (AO) system, finite time delays contribute a relatively large amount to the overall wavefront error. The temporal error, due to the time delays, adds to the speckle halo which is visible in the science plane of a high contrast imaging (HCI) instrument. The halo limits the inner working angle, preventing HCI from probing regions where we expect Earth-like planets. Our research focuses on understanding the non-stationary behavior of atmospheric turbulence and its effects on the temporal error and the contrast. The wind vector greatly influences the turbulence-induced wavefront phase error. In the framework of the von Karman power spectral density (PSD) of wavefront phase, the wind speed changes the cut-off frequency as well as the gain of the spectrum. We aim to understand the behavior of the wind vector on sub-second timescales using data from the Thirty Meter Telescope site testing campaign at Mauna Kea. The nocturnal measurements we study are from 287 nights throughout the years of 2006-2008, taken at a height of 7 m with a maximum sampling rate of 60 Hz. We first compare the observational PSD to the Kaimal PSD. We then present an expression for the observational PSD, a fit to a more general PSD similar to the Kaimal PSD, to describe the wind speed located at Area E (northern plateau) on Mauna Kea. Using the fitted PSD, we construct a fractionally integrated ARMA model that can be used to create an artificial wind speed time series to be fed into phase screen simulations to generate realistic wind-varying phase screens. We examine how the contrast, achieved by the AO system, varies with the wind fluctuations.

Published
2018

2. ERIS: revitalising an adaptive optics instrument for the VLT

Author

Davies, Richard, primary, Esposito, Simone, primary, Schmid, Hans Martin, primary, Agapito, G., primary, Agudo Berbel, A., primary, Baruffolo, A., primary, Biliotti, V., primary, Biller, B., primary, Boehle, A., primary, Cresci, G., primary, Doelman, D., primary, Dorn, R., primary, Eisenhauer, F., primary, Fantinel, D., primary, Ferruzzi, D., primary, Feuchtgruber, H., primary, Gemperlein, H., primary, George, E., primary, Giordano, C., primary, Grani, P., primary, Henry, D., primary, Huber, H., primary, Keller, C., primary, Kühn, J., primary, Kuntschner, H., primary, Lightfoot, J., primary, Lunney, D., primary, Mannucci, F., primary, March, S., primary, Neeser, M., primary, Pearson, D., primary, Quanz, S., primary, Riccardi, A., primary, Sturm, E., primary, Xompero, M., primary, Taylor, William D., primary, Black, M., primary, Briguglio, B., primary, Buron, A., primary, Carbonaro, L., primary, Cortes, A., primary, Deysenroth, M., primary, Di Cianno, A., primary, Di Rico, G., primary, Dolci, M., primary, Förster Schreiber, N., primary, Gao, X., primary, Genzel, R., primary, Gillessen, S., primary, Glauser, A., primary, Glindemann, A., primary, Hartl, M., primary, Heijmans, J., primary, Kasper, M., primary, Kenworthy, M., primary, MacIntosh, M., primary, Patapis, P., primary, Plattner, M., primary, Puglisi, A., primary, Rau, C., primary, Salasnich, B., primary, Schubert, J., primary, Snik, F., primary, Valentini, A., primary, Waring, C., primary, and Wiezorrek, E., primary

Published
2018
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3. Exoplanet science with the LBTI: instrument status and plans

Author

Defrère, D., additional, Hinz, P., additional, Skemer, A., additional, Bailey, V., additional, Downey, E., additional, Durney, O., additional, Eisner, J., additional, Hill, J. M., additional, Hoffmann, W. F., additional, Leisenring, J., additional, McMahon, T., additional, Montoya, M., additional, Spalding, E., additional, Stone, J., additional, Vaz, A., additional, Absil, O., additional, Esposito, S., additional, Kenworthy, M., additional, Mennesson, B., additional, Millan-Gabet, R., additional, Nelson, M., additional, Puglisi, A., additional, Skrutskie, M. F., additional, and Wilson, J., additional

Published
2015
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4. Focal-plane wavefront sensing with high-order adaptive optics systems

Author

Korkiakoski, V.A. (author), Keller, C.U. (author), Doelman, N. (author), Kenworthy, M. (author), Otten, G. (author), Verhaegen, M. (author), Korkiakoski, V.A. (author), Keller, C.U. (author), Doelman, N. (author), Kenworthy, M. (author), Otten, G. (author), and Verhaegen, M. (author)

Abstract

We investigate methods to calibrate the non-common path aberrations at an adaptive optics system having a wavefront-correcting device working with an extremely high resolution (larger than 150x150 correcting elements). We use focal-plane images collected successively, the corresponding phase-diversity information and numerically efficient algorithms to calculate the required wavefront updates. Different approaches are considered in numerical simulations, and laboratory experiments are shown to confirm the results. We compare the performances of the standard Gerchberg-Saxton algorithm, Fast and Furious (use of small-phase assumption to take advantage of linearisation) and recently proposed phase-retrieval methods based on convex optimisation. The results indicate that the calibration task is easiest with algorithms similar to Fast and Furious, at least in the framework we considered., Delft Center for Systems and Control, Mechanical, Maritime and Materials Engineering

Published
2014

5. Focal-plane wavefront sensing with high-order adaptive optics systems

Author

Korkiakoski, Visa, Keller, Christoph U., Doelman, Neik, Kenworthy, M A, Otten, Gilles, Verhaegen, Michel, Korkiakoski, Visa, Keller, Christoph U., Doelman, Neik, Kenworthy, M A, Otten, Gilles, and Verhaegen, Michel

Abstract

We investigate methods to calibrate the non-common path aberrations at an adaptive optics system having a wavefront-correcting device working with an extremely high resolution (larger than 150x150 correcting elements). We use focal-plane images collected successively, the corresponding phase-diversity information and numerically efficient algorithms to calculate the required wavefront updates. Different approaches are considered in numerical simulations, and laboratory experiments are shown to confirm the results. We compare the performances of the standard Gerchberg-Saxton algorithm, Fast and Furious (use of small-phase assumption to take advantage of linearisation) and recently proposed phase-retrieval methods based on convex optimisation. The results indicate that the calibration task is easiest with algorithms similar to Fast and Furious, at least in the framework we considered. ©

Published
2014

6. L'-band AGPM vector vortex coronagraph's first light on LBTI/LMIRCam

Author

Defrère, D., additional, Absil, O., additional, Hinz, P., additional, Kuhn, J., additional, Mawet, D., additional, Mennesson, B., additional, Skemer, A., additional, Wallace, K., additional, Bailey, V., additional, Downey, E., additional, Delacroix, C., additional, Durney, O., additional, Forsberg, P., additional, Gomez, C., additional, Habraken, S., additional, Hoffmann, W. F., additional, Karlsson, M., additional, Kenworthy, M., additional, Leisenring, J., additional, Montoya, M., additional, Pueyo, L., additional, Skrutskie, M., additional, and Surdej, J,, additional

Published
2014
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7. On-sky operations and performance of LMIRcam at the Large Binocular Telescope

Author

Leisenring, J. M., primary, Skrutskie, M. F., additional, Hinz, P. M., additional, Skemer, A., additional, Bailey, V., additional, Eisner, J., additional, Garnavich, P., additional, Hoffmann, W. F., additional, Jones, T., additional, Kenworthy, M., additional, Kuzmenko, P., additional, Meyer, M., additional, Nelson, M., additional, Rodigas, T. J., additional, Wilson, J. C., additional, and Vaitheeswaran, V., additional

Published
2012
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