Conception

Abstract

The father of the telescope we today know as UKIRT was Professor Jim Ring of the Imperial College of Science and Technology, London. He was an experimental physicist who graduated from Manchester University in the 1950s, lectured there for a time, moved to the University of Hull in 1961 and then to London in 1967 where he set up an infrared astronomy group. Jim Ring was interested both in both astronomical instruments and in telescope design and wanted to explore the limits of telescopes as the diameters of their primary mirrors was increased. In particular he sought to challenge the canonical cost-to-diameter relationship for telescope construction which said that, because of the cost of steel and concrete, the budget for a telescope of traditional design increased as about the third power of the primary mirror diameter. At a time when one arcsecond seeing was assumed to be the limit achievable from the ground, he wanted to know how big a mirror with acceptable image quality could be made. He believed that by replacing a conventional primary mirror, i.e. one with a diameter to thickness ratio of about 6 to 1, with a thinner one supported by air filled pads the mass of the mirror and its supporting cell could be significantly reduced. In turn, the mass of steel and concrete needed to support the optics, and hence the cost, would be lower and this virtuous circle would make larger telescopes more affordable.