Opto-Mechanical Design and Testing of the VLT Tertiary Mirrors

摘要

The Tertiary Mirrors for the ESO Very Large Telescope project consist of four optical flats (elliptical, 890 x 1260 mm~2). The achieved opto-mechanical design is challenging since it provides high optical overall quality combined with high stiffness (70 Hz Eigenfrequency) and low mass (total mass of 180 kg for the complete unit). Schott (Mainz, Germany) produces the lightweight Zerodur blanks. Carl Zeiss has designed and manufactured the mirror and its support cell. Last not least it became necessary to install the biggest testing equipment for flats in Europe to guarantee for a scientifically correct verification of the quality of the complete unit. All four mirrors have been delivered to ESO.