(griech.)opt. Gerät zur Betrachtung von sehr kleinen Gegenständen oder Strukturen. Das M. besteht wie das Fernrohr aus zwei Linsensystemen, deren eines als Objektiv dem zu betrachtenden Gegenstand zugewandt ist, während das andere als Okular von dem so vergrößerten (umgekehrten) Bild nochmals eine Vergrößerung für das Auge (oder die Kamera) liefert. Das Auflösungsvermögen eines solchen Licht-M. kann bis zu einem 1/1 000 mm reichen; wesentl. leistungsfähiger ist das Elektronenmikroskop.
Instrument for magnification with high resolution for detail. Optical and electron microscopes are the ones chiefly in use; other types include acoustic, scanning tunneling, and atomic force microscopes. In 1988 a scanning tunneling microscope was used to photograph a single protein molecule for the first time.
The optical microscope usually has two sets of glass lenses and an eyepiece. It was invented 1609 in the Netherlands by Zacharias Janssen (1580–c. 1638). Fluorescence microscopy makes use of fluorescent dyes to illuminate samples, or to highlight the presence of particular substances within a sample. Various illumination systems are also used to highlight details.
The transmission electron microscope, developed from 1932, passes a beam of electrons, instead of a beam of light, through a specimen. Since electrons are not visible, the eyepiece is replaced with a fluorescent screen or photographic plate; far higher magnification and resolution are possible than with the optical microscope.
The scanning electron microscope (SEM), developed in the mid-1960s, moves a fine beam of electrons over the surface of a specimen, the reflected electrons being collected to form the image. The specimen has to be in a vacuum chamber.
The acoustic microscope passes an ultrasonic (ultrahigh-frequency sound) wave through the specimen, the transmitted sound being used to form an image on a computer screen.
The scanned-probe microscope, developed in the late 1980s, runs a probe, with a tip so fine that it may consist only of a single atom, across the surface of the specimen, which requires no special preparation. In the scanning tunneling microscope, an electric current that flows through the probe is used to construct an image of the specimen. In the atomic force microscope, the force felt by the probe is measured and used to form the image. These instruments can magnify a million times and give images of single atoms.
An instrument that magnifies the image of small objects.