In order to get to the answer of this question, we have to make it clear what a Compound Microscope is. It is a magnifying object that features at least two lenses placed in a tube: an eyepiece and an objective lens, used to see objects that are too small for the naked eye, using the light.
You’ll say: you’ve described all the microscopes.
Well, yes. Generally, all today’s light microscopes, except for the 3D (stereo) microscopes, are Compound microscopes. So, what we are going to answer is who developed today’s light microscopes.
But first, a little bit of pre-compound microscope history.
History of optical light microscopes
In the 2nd Century BC, Claudius Ptolemy a Greco-Egyptian writer, known as a mathematician, astronomer, geographer, astrologer, experimented and reported a twig to curve in water and he accurately computed the angles.
In the 1st Century, when glass was invented, the Romans started experimenting with it. Using different shapes of glass they noticed that objects seemed different in size when viewed through this material.
They discovered that an object viewed from thick in the middle and thin on the edges glass looked larger. So, they discovered the lenses, that were called magnifiers or burning glasses. The word lens is actually derived from the Latin word lentil, as they were named because they resembled the shape of a lentil bean.
After that, it wasn’t until the 12th Century, when the first eye glass was made, providing the one wearing it an element of magnification to one eye. Spectacle makers started producing lenses to be worn as glasses. It is said the inventor to be Salvino D’Armate from Italy, but this claim was shown to be a hoax.
From eyeglasses to compound microscopes
From the first magnifying eyeglass to the compound microscope had to pass almost 4 centuries.
In the late 16 and early 17th century, it was discovered that optical instruments could be made by combining lenses.
It’s said that two Dutch spectacle makers, Hans and Zacharias Jansen, the father and his son, were the first to start experimenting with lenses. They put more lenses in a tube and discovered that the object the lens tube was pointed at appeared greatly enlarged. Much larger than a simple magnifying glass could achieve by itself.
These first microscopes weren’t used as scientific tool, since the maximum magnification could get only up to 9x, with somewhat blurry images.
The first use of compound microscopes
The first man to make and use a real microscope was Anton van Leeuwenhoek (1632-1723), a Dutch draper and scientist, in the late 17th century.
He combined many lenses in a lens tube and managed to get a a magnifying power of 270x and could view objects one millionth of a meter (other microscopes of the time were lucky to achieve 50x magnification).
That helped him make many discoveries by using his microscopes. He was the first to see and describe bacteria, yeast plants, the teeming life in a drop of water, and the circulation of blood corpuscles in capillaries.
His work was then developed by the English scientist Robert Hooke, who published the first work of microscopic studies, Micrographia, in 1665.
It is his most famous work and it is notable for the stunning illustrations. Not having how to capture the images that he saw through the microscope at that time, he had to draw them himself.
The book presents Hooke’s observations through the microscope. With the use of a primitive compound microscope, he observed all sorts of things (snow, a needle, a razor, etc.). The most important observations he made were done on fleas and cork. He looked at the fleas, and observed their tiny hairs on their bodies. He saw the pores on the cork and called them “cells”, without knowing that he had discovered plant cells.
The great achievements in microscopy, didn’t bring much change to the microscopes over the next 200 years, even though there were imperfections when viewing an object due to the different refraction of light.
In the 1850s, German engineer Carl Zeiss started refining the lenses used in the microscopes he manufactured. In the 1880s, he hired glass specialist Otto Schott, who conducted research on optical glass, greatly contributing to the improvement of the optical quality of the microscope.
Ernst Abbe has to be mentioned, who was hired by Zeiss to improve the manufacturing process of optical instruments, which back then was largely based on trial and error. In a long and fruitful collaboration, Abbe carried out theoretical studies of optical principles, improving the understanding of the optical quality of a microscope.
Today’s compound microscopes
As technology advanced together with the optics, today’s microscopes were created.
Since these microscopes use the light in magnifying objects, they are only able focus on objects that are at least the size of a wavelength of light (usually, a wavelength of around 550 nm is assumed). So, the theoretical minimum size able to be viewed by an optical microscope is 200nm (as defined by Abbe).
Other types of microscopes, like the electron microscope, can magnify images thousands of times smaller than a wavelength of light.
So in the development of the today’s light microscopes were included even the Greeks and the Romans, since it was then when it was first experimented with the light diffraction in water and from glass. Everything after that is a logical consequence of the development of the human mind and technological progress.