1932: Transparent biological materials are studied for the first time using Frits Xernike's invention of the phase-contrast microscope.

1938: Just six years after the invention of the phase contrast microscope comes the electron microscope, developed by Ernst Ruska, who realized that using electrons in microscopy enhanced resolution.

1981: 3-D specimen images possible with the invention of the scanning tunneling microscope by Gerd Binnig and Heinrich Rohrer.

A Simple Microscope has a single lens. This was usually of small aperture to reduce the blurring or 'spherical aberration' caused by the curvature of the lens. Simple microscopes relied on natural light around the object or a direct form of illumination passing right through it if it was translucent. As many kinds of lens can be used in the hand as a 'simple' microscope, it is not really possible to assign a starting date for the science. The diagram to the left shows a suggested design by Descartes for a hand-held simple microscope using a concave mirror to produce a virtual image when held close to the eye in 1637. The first known image of a microscope is a drawing by Isaac Beeckman of six years earlier. Quite apart from the quality of its workmanship, the user required good eyesight to make the most of such an instrument.

The 'inventor' of the microscope is probably lost to history, however microscopy as we understand it was possibly introduced by the Dutch spectacle-makers Zacharias and Hans Janssen of Middelburg. The Janssens produced a compound microscope in 1595 capable of magnifying specimens up to ten times when fully extended.

A Compound Microscope has a convex objective lens (closest to the object being viewed e.g. a specimen) and convex eyepiece. The ocular lens magnifies the 'real' image that has already been formed by the objective such that the observer is actually viewing an enlarged virtual image. The development of the compound microscope is closely tied in with that of another instrument, the telescope but for a skilled user the simple microscope yielded better results until the mid 18th century. Kircher described various 'smicroscopes' (sic) in 1646, concluding that the best type was a tube containing a glass sphere at one end onto which you would place the object to be viewed. i.e. the best simple microscopes were still being recommended above the compound types available.

Early compound microscopes were very inefficient and the image quality was affected by significant chromatic and spherical aberration, but quite large instruments (over a foot long) with a reasonably high power were available by the first decade of the seventeenth century.