Microscopes are amazing tools that have enabled man to make new scientific discoveries, diagnose and treat human disease, as well as make intricate things that require powerful magnification, resolution and illumination. The uses of optical microscopes are almost endless, but they weren’t invented overnight, in fact they have a long and vibrant history involving numerous significant milestones and innovations. So where did it all start?
Since time began, man has imagined what it would be like to see things beyond the naked eye. The exact time at which man started to use lenses is unknown, but there is evidence of that for over 2000 years glass making light bend has been known.
In the 2nd Century BC Claudius Ptolemy documented a stick seeming to bend when submerged in water. In 50-80 AD Emperor Nero used emeralds to watch Gladiators and lenses were first used for spectacles by D’Armato late 1200’s.
The First Microscope
In the 1590’s, Zaccharias Janssen and his father Hans began to use lenses for the first time. They made a very infantile microscope consisting of lenses within a tube and observed the object at the end of the tube appeared enlarged. Although this wasn’t a working microscope, it certainly paved the way for new innovations.
Between 1632-1723 Antony Van Leeuwenhoek was the first man to create a working microscope. It was very simple, yet achieved the highest magnification so far at a power of x270. This was the first microscope that was really useful.
In the 17th century, the first compound microscope was developed, this is microscope which utilizes two lenses, an objective lens and an eye piece or ocular lens. This advanced magnification significantly as in effect one lens is able to be magnified by the other, creating a superior microscope.
The limit of every microscope is its resolving power or resolution, in simple terms this is the smallest distance that can be distinguished between two points. This is different to magnification, which refers to the size of the image only.
In the middle of the 17th century Robert Hooke discovered the cell, one of the most significant biological discoveries. Hooke is also attributed to using the first microscope with three lenses, which is still used today. He observed “cells” in cork and named them after monastic rooms he said reminded him of what he saw.
In the late 1800’s microscope design improved greatly due to the work of the German company Ziess, Ernst Abbe, Otto Schott and August Koehler. These individuals solved many of the barriers with older microscopes giving rise to new, super powerful microscopes that had better optics and lighting than ever before, being able to achieve powerful magnification and resolution.
In 1902-Ives developed binocular eyepieces, and in 1935-Zeiss phase contrast microscopy, leading to the best optical microscopes to date.
All microscopes are limited by resolution, and due to the nature of light itself resolution and magnification are limited. To overcome this barrier, the electron microscope was developed that replaces light photons with an electron beam. This has led to magnifications of x1,000,000 and resolution of less than 2nm, which is an incredible feat.