Extreme adaptive optics system optimization for high contrast imaging with the high order test bench

Tesis doctoral inédita. Universidad Autónoma de Madrid., Facultad de Ciencias, Departamento de Física Teórica. Fecha de lectura: 20-06-201

FFREE: a Fresnel-FRee Experiment for EPICS, the EELT planets imager

The purpose of FFREE - the new optical bench devoted to experiments on high-contrast imaging at LAOG - consists in the validation of algorithms based on off-line calibration techniques and adaptive optics (AO) respectively for the wavefront measurement and its compensation. The aim is the rejection of the static speckles pattern arising in a focal plane after a diffraction suppression system (based on apodization or coronagraphy) by wavefront pre-compensation. To this aim, FFREE has been optimized to minimize Fresnel propagation over a large near infrared (NIR) bandwidth in a way allowing efficient rejection up to the AO control radius, it stands then as a demonstrator for the future implementation of the optics that will be common to the scientific instrumentation installed on EPICS.Comment: 12 pages, 15 figures, Proceeding 7736120 of the SPIE Conference "Adaptive Optics Systems II", monday 28 June 2010, San Diego, California, US

VLTI status update: a decade of operations and beyond

We present the latest update of the European Southern Observatory's Very Large Telescope interferometer (VLTI). The operations of VLTI have greatly improved in the past years: reduction of the execution time; better offering of telescopes configurations; improvements on AMBER limiting magnitudes; study of polarization effects and control for single mode fibres; fringe tracking real time data, etc. We present some of these improvements and also quantify the operational improvements using a performance metric. We take the opportunity of the first decade of operations to reflect on the VLTI community which is analyzed quantitatively and qualitatively. Finally, we present briefly the preparatory work for the arrival of the second generation instruments GRAVITY and MATISSE.Comment: 10 pages, 7 figures, Proceedings of the SPIE, 9146-1

Halftoning for High-contrast Imaging: Developments for the SPHERE and EPICS Instruments

International audienceControlling the amplitude of light is crucial for many scientific applications, such as in imaging systems, astronomical instruments or laser physics. We provide a brief overview of recent R&D activities at ESO using halftoning, the process of presenting a continuous image through use of dots. Customised filters with spatially varying transmission are produced using a binary array of metal pixels that offers excellent control of the local transmission. Applications to the production of an apodiser for the VLT SPHERE instrument and a mask for E-ELT EPICS are presented

Halftoning for High-contrast Imaging: Developments for the SPHERE and EPICS Instruments

International audienceControlling the amplitude of light is crucial for many scientific applications, such as in imaging systems, astronomical instruments or laser physics. We provide a brief overview of recent R&D activities at ESO using halftoning, the process of presenting a continuous image through use of dots. Customised filters with spatially varying transmission are produced using a binary array of metal pixels that offers excellent control of the local transmission. Applications to the production of an apodiser for the VLT SPHERE instrument and a mask for E-ELT EPICS are presented

Halftoning for High-contrast Imaging: Developments for the SPHERE and EPICS Instruments

International audienceControlling the amplitude of light is crucial for many scientific applications, such as in imaging systems, astronomical instruments or laser physics. We provide a brief overview of recent R&D activities at ESO using halftoning, the process of presenting a continuous image through use of dots. Customised filters with spatially varying transmission are produced using a binary array of metal pixels that offers excellent control of the local transmission. Applications to the production of an apodiser for the VLT SPHERE instrument and a mask for E-ELT EPICS are presented

Halftoning for High-contrast Imaging: Developments for the SPHERE and EPICS Instruments

The Messenger. 2009. vol. 13

Halftoning for high-contrast imaging

International audienc

Halftoning for High-contrast Imaging: Developments for the SPHERE and EPICS Instruments

The Messenger. 2009. vol. 13

Design, analysis, and testing of a microdot apodizer for the Apodized Pupil Lyot Coronagraph

International audienceContext: Coronagraphic techniques are required for detecting exoplanets with future Extremely Large Telescopes. One concept, the Apodized Pupil Lyot Coronagraph (APLC), combines an apodizer in the entrance aperture with a Lyot opaque mask in the focal plane. This paper presents the manufacturing and testing of a microdots apodizer optimized for the near IR. Aims: We attempt to demonstrate the feasibility and performance of binary apodizers for the APLC. This study is also relevant to coronagraph using amplitude pupil apodization. Methods: A binary apodizer was designed using a halftone-dot process, where the binary array of pixels with either 0% or 100% transmission was calculated to fit the required continuous transmission, i.e. local transmission control was obtained by varying the relative density of the opaque and transparent pixels. An error-diffusion algorithm was used to optimize the distribution of pixels that approximated the required field transmission. The prototype was tested with a coronagraphic setup in the near IR. Results: The transmission profile of the prototype agrees with the theoretical shape to within 3% and is achromatic. The observed apodized and coronagraphic images are consistent with theory. However, binary apodizers introduce high frequency noise that is a function of the pixel size. Numerical simulations were used to specify pixel size and minimize this effect, and validated by experiment. Conclusions: This paper demonstrates that binary apodizers are well suited for use in high-contrast imaging coronagraphs. The correct choice of pixel size is important and must be addressed by considering the scientific field of view