Electron microscopy : a versatile tool for material characterization

A microscope (Greek: mikrós, “small” and skopeîn, “to look or see”) is an instrument used for viewing objects that are too small for the naked eye. In other words, it is an instrument to make things look bigger – that is, it magnifies an object that we are looking at. In the ancient times (~2000 BC) the Chinese used water microscopes, made of a lens with tube filled with water to visualize the unseen [1.1]. A water droplet on a leaf as seen in figure 1.1 is a simple example of this kind of lens. In his publication “The Invention of the Microscope”, Bardell reported that around 612 BC the Assyrians manufactured the world’s oldest surviving lenses [1.1]. Nearly 2000 years later in the 14th century, the art of grinding glass lenses was developed in Italy and spectacles were made to improve eyesight [1.2]. However, just the simple lens can magnify only to a limited extent. In the medieval times, the first compound lens was developed in Europe. It is difficult to say who actually invented the compound microscope. Some credit the Dutch spectacle-maker Zacharias Janssen to have invented it in 1590 [1.3]. Another claim for the invention is from Janssen’s competitor, Hans Lippershey [1.3]. The famous Italian scientist, Galileo Galilei soon improved the compound microscope design with a convex and a concave lens in 1609 and called the device an Occhiolino, or “little eye” [1.4]. Like the first microscopes from the mediaeval time, modern optical microscopes still use glass lenses.