The Development of Early Microscopes
The Development of Early Microscopes
A microscope is an instrument used to view or observe specimens that are too small to be seen by the naked eye. The microscope is one indispensable tool in the study of life. Its invention and development is therefore considered as very significant in the science of biology and is one of the most significant parts of its history.
The earliest known instrument to be used for biological studies was simple microscopes in the form of a magnifying lens. A magnifying lens is considered as a simple microscope since it only has one lens. The credit for developing the world’s earliest compound microscope goes to the Janssen brothers. The Janssen brothers were a pair of Dutch spectacle makers.
In 1595, the brothers had the idea of combining two lenses to produce a more magnified view of specimens. This compound microscope was composed to two lenses, one mounted on each end of its tube-within-a-tube barrel. The arrangement of this microscope permitted one lens to magnify the enlarged image of the other lens. It also permitted the instrument to be focused by sliding the metal tube of the barrel together or apart as necessary. Galileo was also known to have contributed to the development of early microscopes and used a compound microscope for his studies. These early types of microscopes had magnifications ranging from 3x to 9x with different sizes of diaphragm openings.
At around 1660, another man of science contributed to the development of the early microscope and along the process made a fundamental discovery in the field of biology. Robert Hooke made many improvements on the early compound microscopes around his time. By observing a very thin slice of bark taken from an oak tree under the microscope, he was able to describe compartments which he then thought to be empty. He called these compartments as “cells” and was published in his work Micrographia in 1665. This put into full swing the development of the theory of the cell as the basic unit of life.
Many years later, a Dutch merchant Anton van Leeuwenhoek began grinding lenses as a hobby. He used these lenses to develop and improve around 250 different microscopes. One of his early microscopes was made up of a tube for holding small fish and a frame in which the magnifying lens was mounted. By holding the lens close to his eye, he could observe blood flowing through vessels in the tail of the fish. Another one of his microscopes was used to observe specimens such as pond water which he found to be teeing with microscopic organisms. He therefore was very instrumental in opening the eyes of the world to the world of microorganisms. He observed several specimens including blood, yeasts and even scrapings from his own teeth.
After being established as being important in the study of specimens for biological studies, the compound microscope went through many processes of improvements and changes. These developments were done by several individuals to better serve their purpose. In 1830 for example, Joseph Jackson Lister, the father of Joseph Lister made modifications on the microscopes during his time to make them more suitable for microbiological studies, specifically for bacterial studies. His various improvements led to the development of the modern microscope. What followed in the century thereafter was a cascade of developments and advancements for this instrument.
In 1903, Richard Zsigmondy developed a microscope that could study objects below the wavelength of visible light and this was called the ultramicroscope. The phase contrast microscope was invented in 1932 by Frits Zernike so transparent and colorless specimens could be studied. He received a Nobel Prize for this one in 1953. But the most significant advance in the history of the microscope was the invention of the electron microscope which makes use of a beam of electrons to produce a highly detailed image of the specimen.
Ernst Ruska was a co-inventor of this microscope for which he won the Nobel Prize in Physics in 1986. Electrons are allowed to pass through a vacuum at high speeeds until their wavelength is extremely short, only one hundred-thousandth that of white light. They make it possible to view objects as small as the diameter of an atom. In 1981, Gerd Binnig and Heinrich Rohrer invented the scanning tunneling microscope, which up to this time is considered as one of the most powerful microscopes ever developed. These microscopes produce images so highly detailed that they are of the level of the molecules already.