Introduction

Microscopes allow magnified images of illuminated specimens to be viewed using 2 lenses (an objective and an eyepiece lens). Microscopes that use two lenses are called compound microscopes.
Single lens microscopes, of which this antique created by Leeuwenhoek (1632-1723) is an example, use only a single lens to magnify the specimen. Compound microscopes were first invented in the late 16th century in Holland, when Zacharias Janssen and his father discovered that using two lenses greatly aided in magnification. However, compound microscopes of the time suffered from chromatic and spherical aberrations in the lens, which gave single lens microscopes an advantage both in clarity and magnifying power.
In the 19th century, however, these problems with the compound microscope were successfully resolved. Also, up until that time, microscopes had been designed based on experience and the design had no scientific grounds. A German named Ernst Abbe (1840-1905), however, established a method to design microscopes utilizing logical calculations.
Since then, microscope design has progressed rapidly to the present day, with a wide array of advanced microscopes now available depending on specimen and research purpose.

• Leeuwenhoek's microscope