Binocular microscope A microscope with two eyepieces both showing the same view.

Compound microscope An optical microscope that contains more than one lens. A standard compound microscope has two lenses: an objective lens and an eyepiece. If the objective lens has a magnifying power of x8 and the eyepiece has a power of x10, the total magnifying power of the microscope will be x80.

Condenser A lens that concentrates light on to the specimen.

Digital microscope An optical microscope that uses a digital camera to display the magnified image on a computer.

Electron microscope A microscope that uses tiny particles called electrons to magnify objects. Electron microscopes include: scanning electron microscopes (SEMs), transmitting electron microscopes (TEMs) and scanning tunnelling electron microscopes (STMs). Electron microscopes can magnify objects many more times than optical microscopes can.

Eyepiece The lens in a microscope or telescope that the viewer looks into. It magnifies the image made by the objective lens.

Janssen, Zacharias (1580–1638) Dutch spectacle-maker who is thought to have built the first compound microscope in about 1590. Early microscopes had poor-quality lenses and gave blurred images.

Leeuwenhoek, Anton van (1632–1723) Dutch scientist who began making single-lens microscopes in the 1670s. Leeuwenhoek was the first person to observe micro-organisms, such as bacteria.

Magnifying power The magnification achieved by a microscope, for example x10 or x100. If an object is magnified x100 it will appear 100 times larger than it is.

Micrograph A photograph taken using a microscope. Sometimes called a photomicrograph.

Microscope An instrument that magnifies very small objects, allowing the viewer to see detail that is invisible to the naked eye. The early microscopes of the 17th century enabled scientists to view micro-organisms such as bacteria for the first time, helping to understand the cause of some diseases. In the modern world, microscopes are used mostly, but not only, in biology and medical research. There are two types of microscope—optical microscopes and electron microscopes.

Nosepiece The part of an optical microscope that holds the objective lens.

Objective lens A lens in a microscope or telescope that is closest to the object being studied. In an optical microscope, the objective lens gathers light from an object and focuses it to create a magnified image of the object.

Optical microscope A microscope that uses light to create a magnified image of an object. Optical microscopes can only magnify objects up to 2000 times.

Scanning electron microscope (SEM) An electron microscope that uses a narrow beam of electrons to build up a three-dimensional image. The beam scans across the object’s surface and a sensor detects the electrons bouncing off. Unlike other electron microscopes, it can be used to view whole objects, such as insects. SEMs magnify objects up to 500,000 times.

Scanning tunnelling electron microscope (STM) An electron microscope that can magnify specimens up to 100 million times, which is enough to see individual atoms. It scans a charged metal pen over the surface of a specimen, so that electrons jump or “tunnel” between the pen and the surface. This creates a “map” of high points (atoms) and low points (the gaps between them).

Slide A thin piece of glass upon which an object or specimen is fixed to be viewed.

Stage The part of a microscope where an object is placed to be viewed. A hole in the centre of the stage allows light to be directed at the object or specimen.

Stereo microscope An optical microscope that produces a three-dimensional image. Two eyepieces are used, meaning each eye sees a slightly different view, creating a 3-D view of the magnified object.

Transmitting electron microscope (TEM) An electron microscope that fires a beam of electrons through a thin slice of specimen. The electrons scatter off dense areas of specimen but pass through less dense areas, creating a “shadow” image. TEMs magnify objects up to 2 million times.

Consultant: Chris Oxlade