Commissioning of the Adaptive Optics System NAOS-CONICA for the VLT : the way to First Light

Abstract

In October 2002 NAOS-CONICA, one of the most powerful adaptive optics systems was offered to the astronomical community. The instrument is installed at the Very Large Telescope in Chile and operated by the European Southern Observatory. The adaptive optics system NAOS corrects for atmospheric turbulence and provides the near-infrared multi-mode camera and spectrograph CONICA with diffraction limited images. Development of NAOS was achieved by a French consortium, while CONICA was developed by a German consortium under the leadership of the Max-Planck-Institut fur Astronomie, Heidelberg. In the context of this PhD thesis several critical contributions to the successful commissioning were made. The major test and calibration results obtained on the way to First Light, i.e., during the laboratory, integration and commissioning periods are presented. They cover cryogenics, mechanics, optics and detector characteristics of CONICA. A major achievement was the development and implementation of a technique for the calibration of static optical aberrations. Since the instrument is designed to achieve absolute Strehl ratios higher than 70%, even the accumulation of residual static wavefront perturbations arising from optical components in the imaging path, critically affect the overall performance. The technique has been completely implemented for the instrument, and the adaptive optics system automatically corrects the static aberrations according to the different instrument configurations. The presented technique will be of great importance for future adaptive optics systems. Particular attention is payed to the calibration of CONICA's high resolution imaging spectroscopy mode, realized by a cold tunable Fabry-Perot interferometer. A detailed guideline is given of how to process a phase-shift map and the capabilities for 3-dimensional structure analysis are demonstrated at Eta Carinae. A first, high-spatial resolution velocity map is created.