<title>Design and performance of the VLT 8-m coating unit</title>

Abstract

The 8m coating unit for the VLT mirrors is designed for the deposition of high reflective, homogeneous aluminium coatings. For the process of the film deposition the sputter technology is utilised. The design of the following major subsystems is completed : the vacuum vessel and the vacuum generation system, the thin film deposition equipment and the glow discharge cleaning device, the substrate support and rotation system as well as the supporting framework and the auxiliary equipment. Manufacturing of the Coating Unit has started. The pre-assembly and testing activities, which will take place prior to the shipment to the site, are defined. This paper describes the design features and the major performance requirements of the 8m coating unit. The performance of the sputter source design has been verified in a qualification test. The deposition rate, the film thickness and reflectance, as well as the film purity have been measured. The test set-up and the results of the qualification tests of the selected magnetron type are presented and discussed. SPIE Vol. 2871 / 137 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/16/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

Structural Optimization of the Retractable Dome for Four Meter Telescope (FMT)

“…Previous analyses of domes focused mainly on their aerodynamic properties; for instance, Ando et al (1991), Siegmund (1990), andSchneermann (1994) used wind tunnel tests (WT) to study the flushing time, the uplift effect, and the pressure inside the dome. Young (1996), Young & Vogiatzis (2004), Vogiatzis (2008), Chylek et al (2004), MacMynowski et al (2006), MacMynowski & Andersen (2010), and Padin (2002) utilized computational fluid dynamics (CFD) simulation to avoid a long preparation period and the high expense of WT tests to study the wind load of a telescope and search for the optimization plan of the dome.…”