Jean-Claude Richard

Come-on-plus project: an upgrade of the come-on adaptive optics prototype system

This paper is a presentation of the Come-On-Plus adaptive optics system, based on the Come-On prototype. Come-On-PIus will be set up in 1992 on the ESO 3.6 m telescope in La Silla (Chile). It is an upgrade of the Come-On instrument, with a 52 actuator deformable mirror, and 30 Hz correction bandwidth. But the main improvement concerns the wavefront sensing, designed in this instrument for astronomical applications, with a high detectivity wavefront sensor and a specific mirror control algorithm. This system is planned for routine astronomical observing as well as providing design parameters for the adaptive optics system of the ESO Very Large Telescope (VLT).

Electron-bombarded CCD: first results with a prototype tube

The aim of this paper is to show the relevance of the electron bombardment technique of photon counting for astronomical applications, using results obtained both in the laboratory and on the sky with a prototype tube. The potential astronomical applications discussed are in techniques requiring high time resolution, either in an analog or a photon counting mode (wavefront analysis, speckle interferometry, multitelescope interferometry, etc.) and observation of rapidly varying objects. Current prototypes will be used to achieve wavefront analysis in the near future. The first priority in further technical development must obviously be to develop a larger and faster CCD.

Wavefront sensing in imaging through the atmosphere: a detector strategy

Wavefront sensing is a very powerful technique whose capability in the field of diffraction- limited imaging through turbulence has been demonstrated. The ultimate performance of a Hartmann-Shack wavefront sensor is analyzed and used to define a detector choice strategy.

New adaptive optics prototype system for the ESO 3.6-m telescope: Come-on-Plus

Following the successful astronomical runs of the Come-On adaptive optics prototype on the ESO 3.6 m telescope in La Silla, Chile an upgraded version called Come-On-Plus is currently being constructed and was set up in December 1992. This paper describes the main improvements of this new system. In particular, the 52 actuator deformable mirror with 30 Hz closed loop bandwidth, the modal control, the high detectivity wavefront sensor channel, and the infrared imaging channel are presented. Finally, the laboratory tests of each subsystem are analyzed. This second prototype is dedicated to routine astronomical observing as well as providing design parameters for the adaptive optics for the ESO Very Large Telescope (VLT).