Microscopes (Divers)

Microscopes magnify objects and display them visually. The objects' size mostly lies below the resolution of the eye. 

History of the microscope

The principle of magnification was already familiar to the Romans, who knew about magnifying by a water-filled dish of glass. Magnification lenses were applied already in the 16th century. The Dutch spectacle-maker Hans Janssen and his son are known as the inventors of the first composite microscope, built in 1590. The occhiolino was developed in 1609 by Galileo Galilei. An occhiolino is a composite microscope which is made of a convex lens and a concave lens. Christiaan Huygens developed at the end of the 17th century a simple 2-lens ocular system. Oculars based on this principle are produced even today.

Microscopes - principles

A microscope can operate basically by different principles. The light microscope was already developed 1600 years ago. The object was then observed through one or several glass lenses. The physical limit to the resolving power of a classical light microscope depends on the wavelength of the irradiating light, typically about 0.2 micrometres. These regularities were defined at the end of the 19th century by Ernst Abbé, in whose honour the mentioned limit is called the Abbé limit. Higher resolution can be achieved by electron microscopes which were developed in 1930. Electron beams have a shorter wavelength than light. Scanning force microscopes subscribe to another principle. They have a very fine needle, scanning the surface of objects.

Application of microscopes

Microscopes are applied chiefly in medicine, biology and material sciences.

Kinds of microscopes

Typical microscopes are X-ray microscopes, ultrasonic microscopes, helium ion microscopes, Focused ion beam microscopes, photonic force microscopes, magnetic resonance microscopes and neutron microscopes.

Literature

• http://de.wikipedia.org/w/index.php?title=Mikroskop&oldid=8182104 (called: 31.03.11).