Science Fair Project Encyclopedia A microscope (Greek: micron =
small and scopos = aim) is an instrument for viewing objects
that are too small to be seen by the naked or unaided eye. The
science of investigating small objects using such an instrument
is called microscopy, and the term microscopic means minute or
very small, not easily visible with the unaided eye. In other
words, requiring a microscope to examine. The most common type
of microscope—and the first to be invented—is the optical
microscope. This is an optical instrument containing one or more
lenses that produce an enlarged image of an object placed in the
focal plane of the lens(es). See also: Microscopy. Simple
optical microscope A simple microscope, as opposed to a standard
compound microscope (see below) with multiple lenses, is a
microscope that uses only one lens for magnification. Van
Leeuwenhoek's microscopes consisted of a single, small, convex
lens mounted on a plate with a mechanism to hold the material to
be examined (the sample or s