Introduction and historical development

Abstract

In highschool I was taught that the great Greek scientist Archimedes (287 - 212 BC) was instrumental in the defence of his city Syracuse on Sicily against the Roman fleet and army of Marcellus during the Punian War. Among the defensive devices, developed by him, he used parabolic mirrors to concentrate the reflected light from not true, it is fair to say that Archimedes could have done it. He had after all studied the geometrical figures of conic sections and knew about the focussing characteristics of such curves. As such, it would have been one of the earliest examples of applied physics based on pure mathematical knowledge. Note that for his goal to be successful, he needed to construct what is now called an offset reflector, a typical example being the ubiquitous TV-satellite dish. From the definition of the parabola it is immediately clear that a bundle of parallel light rays impinging onto a reflector in the form of a paraboloid of revolution along its symmetry axis will be concentrated towards the focal point of the paraboloid. This simple characteristic has made the parabolic reflector the most widely used device for astronomical telescopes, both in the optical and radio regime, and more recently for transmitting and receiving antennas in microwave communication technology, including satellite communication, as well as the concentration of solar radiation as commercial energy source in solar power stations. the Sun to set the Roman ships afire. The frontispiece picture on page vi of this book represents this feat. Although this story is now considered by historians to be very likely