A historical view of imaging systems and technology

Abstract

AbstractWhen approached from a historical viewpoint the development of many important imaging systems throughout history often share common ground. Extremely important was the development of the idea of mathematical projection which provides methods for making an image that conformally represents the object. The prime example is the discovery of the stereographic projection by Hipparchus of Nicaea in the second century BC. The stereographic projection provided the basis for the astrolabe, an astronomical device that acted both as an instrument of observation and as an analog computer. The stereographic projection and similar ones also provided the basis for the world maps of the ancients which utilized a grid of longitude and latitude. When the ancient Greek books were rediscovered in the Renaissance, the maps provided the impetus for the age of exploration. The Mercator projection of the sixteenth century was obtained as a logarithmic transformation of the stereographic projection. The Mercator projection provided sea captains with maps that had a rectangular grid of latitude and longitude and also had the property that straight lines represented courses of constant compass directions. The development of the telescope and microscope in the early seventeenth century provided means to obtain images that could not be seen by the unaided eye. Galileo's discovery of the moons of Jupiter led to Roemer's determination in 1676 that light travels at a finite velocity. Unknowingly, Roemer also discovered the relativistic Doppler effect, which in the present century helped to establish our concept of the expanding universe. The relativistic Doppler factor mathematically is none other than the expression for the stereographic projection of Hipparchus. The development of high energy physics in this century has led to images of the microworld of subatomic particles. In this environment Einstein's equation E = mc2 finds verification. This equation is a result of the theory of special relativity. The basic mathematics of special relativity is contained in the Lorentz transform. Again we can return to Hipparchus, because the Lorentz transform follows from a sequential application of the stereographic projection.