The microscope is an instrument that focuses light or other radiation through one or more lenses to form a magnified image of a specimen. The microscopehas revolutionized the study of biology and medicine. The instrument has applications in all other scientific and technical areas as well. The electron microscope isanalogous in principle to the light microscope.
The historical development of the microscope:
Magnification by simple lenses has been known from ancient times, but thedevelopment of the modern microscope dates from the construction of compound-lens systems, which occurred some time in the period between 1590 and 1610.
In 1600, Hans andZacharias Jannsen constructed a simple instrument made of a pair of lenses mounted in a sliding tube. In 1611, Johannes Kepler described a compound-lens system using a convexlens.
The man generally considered the founder of microbiology is the Dutch biologist Anton van Leeuwenhoek (1632-1723). He became interested in science when, as abusinessman, he began grinding lenses and building simple microscopes as a hobby. Each microscope consisted of a flat brass or copper plate in which a small, single glass lenswas mounted. The lens was held up to the eye, and the object to be studied was placed on the head of a movable pin just on the other side of the lens.
Leeuwenhoek madeover 400 microscopes, many of which still exist. The most powerful of these instruments can magnify objects about 275 times. He was the first person to observe single-celledanimals (protozoa) with a microscope. He was also the first person to observe clearly and to describe red blood cells in humans and other animals as well as sperm cells.