Francois J. Rigaut

Performance of the Canada-France-Hawaii Telescope Adaptive Optics Bonnette

ABSTRACT Extensive results from the commissioning phase of PUEO, the adaptive optics instrument adaptor for the Canada‐France‐Hawaii Telescope (CFHT), are presented and discussed. Analyses of more than 750 images recorded with a CCD and a near‐IR camera on 16 nights in wavelengths from B to H are used to derive the properties of the compensated wavefront and images in a variety of conditions. The performance characteristics of the system are analyzed and presented in several ways, in terms of delivered Strehl ratios, full width half‐maxima (FWHM), and quantities describing the improvements of both. A qualitative description is given of how the properties of the corrected images result from the structure function of the compensated phase. Under median seeing conditions, PUEO delivers essentially diffraction‐limited images at H and K and images with FWHM ∼ 0 \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepac...

Analytical model for Shack-Hartmann-based adaptive optics systems

In this paper, we present a novel approach to modeling Shack-Hartmann-based adaptive optics (AO) system which allow to easily predict their performance. The idea is to start for the power spectral density (PSD) of the turbulent phase and to derive the PSD of the compensated phase by taking into account the various errors affecting the AO correction, which can be expressed analytically in the Fourier domain. Once the PSD of the compensated phase is known, the computation of the residual point spread function is straightforward.

Future of filled aperture telescopes: is a 100-m feasible?

We explore the scientific case and the conceptual feasibility of giant filled aperture telescopes, in the light of science goals needing an order of magnitude increase in aperture size, and investigate the requirements (and challenges) these imply for possible technical options in the case of a 100 m telescope. The 100-m f/6.4 telescope optical concept is of a four mirror design with segmented, spherical primary and secondary mirrors, and 8-m class aspheric tertiary and quaternary mirrors, providing a 3 arc minutes field of view. Building on the experience of the VLT and other large telescope projects, we investigate mirror fabrication issues, a possible mechanical solution, the requirements for the absolutely essential adaptive optics system and for the instrumentation package, and the implications for budget and schedule.

Design of the Nasmyth adaptive optics system (NAOS) of the VLT

NAOS is the adaptive optics system to be installed at one of the Nasmyth foci of the very large telescope (VLT). It will provide compensated image to the high angular resolution IR spectro-imaging camera which covers the 1-5 micrometers spectral bands. our French consortium is the sub-contractor of ESO for the design, manufacturing, integration and test of NAOS. For bright sources, the specification is to reach 70 percent Strehl ratio under average seeing conditions. Two wavefront sensors, one in the visible spectral range and one in the near IR spectral range, will equip the adaptive optics system. We foresee to obtained the first light at the VLT unit telescope 1 in mid-2000.

PUEO: the Canada-France-Hawaii Telescope adaptive optics bonnette I: system description

The Canada-France-Hawaii Telescope is developing an Adaptive Optics Instrument Adaptor for general use at its 3.6 m telescope. It consists of a 19 electrode, bimorph deformable mirror (1:6:12) used with a 19 sub-aperture, curvature wavefront sensor.

Deconvolution method for accurate astrometry and photometry on adaptive optics images of stellar fields

We present a method to accurately find the position and photometry of each source in a stellar field blurred by the adaptive optics corrected point spread function (AO PSF). The method takes into account the specificities of the object as well as the specificities of the AO PSF. The algorithm is based on the minimization in the Fourier domain of a regularized least square objective function using the Levenberg-Marquardt method. Astrometric and photometric data of each source are retrieved with an excellent accuracy and super-resolution is achieved. The performance of the method in terms of accuracy is assessed on simulated fields. Then, we present results obtained on images of the Galactic Center, a very crowded field on which the method shows remarkable robustness and stability.

SINFONI: a near-infrared AO-assisted integral field spectrometer for the VLT

SINFONI, the SINgle Faint Object Near-IR Investigation, is an instrument for the very large telescope, designed to provide spectroscopy at the telescope diffraction limit in the near-IR. This unique capability is achieved by combining two state-of-the-art developments, an integral field spectrometer and a curvature sensor based adaptive optics system. SINFONI is a collaborative effort by the Max-Planck- Institut fuer extraterrsetrische Physik and the European Southern Observatory.

Canada-France-Hawaii Telescope adaptive optics bonnette II: simulations and control

We report on the results of the system simulation software written at Canada-France-Hawaii Telescope, to predict and optimize the performance of our adaptive optics bonnette presently under construction. The individual simulation elements, atmospheric simulator, curvature sensor, bimorph mirror and control loop, are reviewed with an emphasis on the basic properties of curvature sensors. Optimization of the extra-focal distance parameter and its consequences are discussed. We then present results of whole system simulations, and quantify the main sources of error. Some results, including noise, are reported. In a second part, we present our view of modal control and detail the construction of the modal basis. We also report briefly on modal gain optimization.

Adaptive optics prototype system for infrared astronomy: I. System description

This paper is a presentation of the so-called COME-ON adaptive optics prototype system developed jointly by four European institutions. This system has been tested on the 1.52m telescope of the Observatoire de Haute Provence on October 12 to 23 and November 13 to 24, 1989. Diffration-limited infrared imaging has been achieved during these first tests. The adaptive optics system consists of a 19 actuator deformable mirror and a Hartmann-Shack type wavefront sensor. In this instrument the wavefront sensing is performed at visible wavelengths while the correction is performed for near infrared imaging (1 .2 to 5 .tm). Specialized computers drive the deformable mirror and a tip-tilt mirror. The bandwidth of the servo-loop is 9 Hz at 0 dB point in open-loop. The results obtained with this instrument will be very useful for the design of the future adaptive optics system for the ESO Very Large Telescope (VLT).

60 Milliarcsecond Near-Infrared Imaging of 3C 273 with Altair and Gemini

We report data from the commissioning run of the Altair adaptive optics instrument on Gemini North. The bright QSO 3C 273 was observed at f/32 in the H and J bands, and at f/14 with J band, using the QSO itself as guide star. Resolution of approximately 60 mas full width at half‐maximum (FWHM) was achieved in H band. The data and point‐spread function are compared with those from the Hubble Space Telescope (HST). The Altair data allow a measurement of the spheroidal inner host galaxy to radii down to about 40 mas. A bright knot seen in visible wavelengths with the Advanced Camera for Surveys (ACS) instrument on HST is seen in the J but not the H band, and the dust lane seen with ACS is less visible, as expected. Other morphological features, and the jet, are discussed.