The Compound Microscope

Capable of greater magnification than traditional microscopes, the compound microscope can produce an image up to about 2,000 times larger than the object. It is a great improvement over the traditional light microscope that was used by Van Leeuwenhoek to discover microorganisms in 1676, which was a single lens, or "simple", microscope. Despite the vastly more sophisticated methods of image amplification we have today, the compound microscope is still invaluable due to its accurate reproduction of color and ease of use.

A Mere 400 Years After Eyeglasses It is reported by historians that Dutch eyeglass makers invented the first microscope around 1590. Hans Janssen and his son Zacharias Janssen (a known counterfeiter and contributor to the invention of the telescope) fashioned lenses to help those with seriously deteriorated eyesight. Zacharias is also generally assumed to be the inventor of the compound microscope, then capable of 10X magnification.

Refining the Design
Oddly enough, it was not for more than 50 years that microscopes finally played a role in the sciences. Thanks in part to the 1661 discovery of blood circulation in the lungs of a frog by Marcello Marlphigi, the microscope was put on the fast track for improvement. The first common sense improvement worked great; an eyecup was added to maintain the proper distance between eye and scope. Further improvements needed still more refining, though. Various configurations of light sources, objective lens, and field lens resulted in poor images with low light or spherical aberrations.

Anton van Leeuwenhoek improved the simple microscope to magnify images accurately up to 270 times. His 1676 discovery of microorganisms remains one of the pivotal moments in the history of life sciences. While microscopy did make progress in the following 200 years, it was not until the 20th century that we achieved images free from blur and aberrations.

The Modern Microscope
Currently, it is relatively easy to manufacture lenses that work in concert to produce impeccable images. Compound microscopes that achieve magnification levels up to 400X can be purchased for less than a decent coffeemaker and people the world over are experiencing sights once enjoyed by an elite few. In fact, a modern technique known as Sarfus enables the use of an upright compound microscope to increase the image by about 100 times. This enables real time, direct observations of nano-objects previously only observed with more sophisticated microscopes.