The Challenge of Optics in Future Extremely Large Telescopes

Abstract

The development of astronomical telescopes has largely been driven by the capability to produce accurate and complex surfaces that are necessary to correct the geometrical aberrations existing in any optical instrument. Although the optical configurations used in the most recent telescopes were discovered almost 400 years ago, the technical difficulties and challenges to manufacture these optics did not allow one to contemplate the successful building of such mirrors until modern technologies such as computer controlled polishing and the laser interferometer were available. In this chapter we will show that extremely large telescopes of the future will require much more accurate optics than any other telescope in the past. The need for these highly accurate mirrors is driven by the most ambitious scientific goals, such as Earth-like planet detection and spectroscopy. To meet these challenges, several techniques for polishing and figuring mirrors have been developed in Europe and in the United States and some of the most promising will be reported in this chapter. The first results in development of prototypes demonstrate that necessary polishing technology is now available to meet the most stringent requirements set by the astronomers.