A telescope made with cylinders Constructing a 3 m sub-millimeterwave prototype

Abstract

A novel four mirror optics suitable to constructing large telescopes at optical and submillimeter wavelengths has been proposed recently. To prove this concept, a 3 m prototype based on this optics is being constructed. Of the four mirrors in the proposed design, three are parabolic cylinders. We have explored and demonstrated an economical method of making parabolic cylindrical panels to an rms accuracy of 20 μm, sufficient to observe up to a frequency of 1000 – 1500 GHz. The tertiary and quaternary themselves will form a telescope of 0.6 m2 area with a fan beam, allowing us to characterise this part of the optics. In this paper, we present the fabrication details of the second pair of mirrors and their physical measurements. The beam measurements await the completion of a radiometer which is under construction.