Design of 2-m to 6-m Liquid Mirror Containers.pdfVIP

11 Design of 2-m to 6-m Liquid Mirror Containers. Robert Content University of Durham, Astronomical Instrumentation Group, Department of Physics, South Road, Durham, DH1 3LE, UK Subject headings: Telescopes, Instrumentation, Liquid Mirrors 22 Abstract A new design is proposed for large (up to 6-m) liquid mirror containers. The design uses Kevlar, foam and aluminum, as in previous designs, but with a different configuration that makes the container lighter, stronger and more rigid. The results of finite element analysis are presented, consisting in the deformations due to temperature changes and to weight, and in the security factor for each material when maximum constraints are applied. Tilt rigidity is also analyzed. They show that the composite material construction technique gives a good performance up to 6 meter diameters. The figures and tables contained in this paper can be used as recipes to build containers having diameters between 2 and 6 meters. 1. Introduction The technology of liquid mirrors has now been fully demonstrated in the laboratory (Borra et al. 1992; Borra, Content Girard 1993; Girard Borra 1997; Tremblay Borra 2000) and in the field (Borra et al. 1988; Hickson et al. 1994; Sica et al. 1995; Wuerker 1997; Hickson Mulrooney 1998) for 1-m to 4-m class systems. By making available for the first time large optical quality optics at low cost, it increases the performances in many domains of sciences. The most complete facility to date is the NASA Orbital Debris Observatory (NODO) which uses a 3-m liquid mirror (Potter Mulrooney 1997; Mulrooney 1998). This telescope has also been used to make astronomical research (Content et al. 1989; Cabanac, Borra Beauchemin 1998) that proves the large scientific return for a given cost and the feasability of long astronomical programs using liquid mirror observatories. 33 Liquid mirror is the technology that gives the largest étendu (product of primary surface by field solid angle: the A? product) per dolla