Astronomical telescopes

Sputtered silver mirrors are used for solar energy (qv) collectors and astronomical telescope mirrors. Approximately 3 t/yr of silver are used in the United States for low emissivity windows. 

Hardy, J.W., Adaptive optics for astronomical telescopes, Oxford University Press, 1998... 

Keywords astronomical telescopes, aberrations, telescope designs... 

The development of adaptive optic (AO) systems to correct for wavefront distortions introduced by the atmosphere represents one of the major advances in astronomical telescope technology of the 20th century. However, in spite of the great progress in AO, sky coverage is limited to sources located near bright stars that provide a measure of wavefront distortions. 

Table 3.2 The collection dish of the JCMT telescope on Hawaii. The 15m diameter JCMT is the largest astronomical telescope in the world designed specifically for sub-millimeter astronomy. (Reproduced by permission of the James Clerk Maxwell Radio Telescope)...

Having defined the aim, let us return to the question of observing equipment. The purpose of the astronomical telescope is to gather light from celestial bodies and to focus it. This light is then dissected by means of a dispersive tool such... 

To a good analogy, before the invention of STM, the determination of surface structure was similar to the case of speculating on the landscape of a planet from information taken through an astronomical telescope. In analogy to spacecraft, the STM sends electrons to the vicinity of the "planets" to take direct, close-up photographs. 

Perhaps the most interesting application of a parabola is in the design of mirrors for astronomical telescopes. The rays of light from a star, a galaxy, or even such a nearby celestial object as a planet are essentially parallel. The reflective property of a parabola sends a ray that is parallel to the parabola s axis through the focus. Therefore, if one grinds a mirror with its surface in the shape of a parabola rotated around its axis and if one tilts such a mirror so that its axis points at a star, all the light from that star which strikes the mirror will be concentrated at the mirror s focus. 

A large batch coating system especially designed to coat astronomical telescope mirrors with A1 films is shown in Fig. 37. The mirror substrate to be coated is made of glass ceramics, its thickness is 60 cm and the weight is about 14 tons. 

Thin-film products have always been deposited on substrates of relatively small dimensions. Exceptions have been the wet chemical silvering for mirror production and perhaps the making of special oxidic heat protection layer systems by dip coating. A few other rare examples for large area coating can be given in film deposition on large astronomical telescope mirrors and on 1.2 m diameter optical components for the lasers used in nuclear fusion experiments. 

Within the scientific world, computers are used for two main tasks performing numerically intensive calculations and analyzing large amounts of data. Such data can, for example, be pictures generated by astronomical telescopes or gene sequences in the bioinformatics area that need to be compared. The numerically intensive tasks are typically related to simulating the behaviour of the real world, by a more or less sophisticated computational model. The main problem in such simulations is the multi-scale nature of real-world problems, spanning from sub-nano to millimetres (10 ° - 10" ) in spatial dimensions, and from femto- to milliseconds (10 - 10 ) in the time domain. 

Astronomical telescope drives, optical path alignment, chopping... 

Optical astronomical telescopes fall into two main classes refracting telescopes (or refractors), which use lenses to form the primary image, and reflecting telescopes (or reflectors), which use mirrors. 

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