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A '''microscope''' is an instrument that enables the user to view objects smaller than can be seen with the naked eye. If not qualified, the word microscope usually refers to an optical compound microscope. Such microscopes can magnify from about 10 to 1000 times.
A '''microscope''' is an instrument that enables the user to view objects smaller than can be seen with the naked eye. The word ''usually'' refers to an optical compound microscope. Other kinds of microscopes will be discussed later.
==Optical compound microscopes==
Optical compound microscopes are broadly similar to telescopes in containing two widely separated lenses or systems of lenses: an ''ocular'' or ''eyepiece'' that you look into, and an ''objective'' which is close to the object that is being observed.
Such microscopes can magnify from about 10 to 1000 times.
The higher powers, however, require special techniques; the object to be observed must be prepared as a flat, thin section, usually stained with special chemicals to make transparent structures visible, cemented under a cover-glass, and used with a special oil-immersion objective, with a drop of oil between the objective and the cover slip. Microscopes in children's science kits may claim high magnifications, but anything over about 50X is "empty magnification" and of no use.
The higher powers, however, require special techniques; the object to be observed must be prepared as a flat, thin section, usually stained with special chemicals to make transparent structures visible, cemented under a cover-glass, and used with a special oil-immersion objective, with a drop of oil between the objective and the cover slip. Microscopes in children's science kits may claim high magnifications, but anything over about 50X is "empty magnification" and of no use.