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

Author's postprint. Paper presented at the International conference on Submillimeter Science & Technology, held during 13-15 October 2004, Organized by Submillimeter Wave Group, PRL, Ahmedabad, India.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 characterize 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