Antonie Van Leeuwenhoek is the first who observe the tiny, unicellular living things but Robert Hooke is the one who confirmed Leeuwenhoek’s observations and was the first to use the term cellZacharias Jansen invented the first compound microscope. Light rays are used to illuminate the specimen while electron beams are used to illuminate the specimen in electron microscopy. All lens in light microscope are made of glass while they are electromagnets in electron microscope. Light microscope have low resolving power while electron microscopes have high resolving power.
Anthony Leeuwenhoek of Holland became very interested in lenses while working with magnifying glasses in a dry goods store. He used the magnifying glass to count threads in woven cloth. He became so interested that he learned how to make lenses. By grinding and polishing, he was able to make small lenses with great curvatures. These rounder lenses produced greater magnification, and his microscopes were able to magnify up to 270X! Anthony Leeuwenhoek became more involved in science and with his new improved microscope was able to see things that no man had ever seen before. He saw bacteria, yeast, blood cells and many tiny animals swimming about in a drop of water. From his great contributions, many discoveries and research papers, Anthony Leeuwenhoek (1632-1723) has since been called the “Father of Microscopy”.
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Reproduction of first compound microscope made by Hans and Zacharias Janssen, circa 1590. From the National Museum of Health and Medicine, Washington, D.C.
Credit: Public domain.
The early Janssen microscopes were compound microscopes, which use at least two lenses. The objective lens is positioned close to the object and produces an image that is picked up and magnified further by the second lens, called the eyepiece.
A Middelburg museum has one of the earliest Janssen microscopes, dated to 1595. It had three sliding tubes for different lenses, no tripod and was capable of magnifying three to nine times the true size. News about the microscopes spread quickly across Europe.
Galileo Galilei soon improved upon the compound microscope design in 1609. Galileo called his device an occhiolino, or “little eye.”
English scientist Robert Hooke improved the microscope, too, and explored the structure of snowflakes, fleas, lice and plants. He coined the term “cell” from the Latin cella, which means “small room,” because he compared the cells he saw in cork to the small rooms that monks lived in. In 1665, and detailed his observations in the book “Micrographia.”
Early compound microscopes provided more magnification than single lens microscopes; however, they also distorted the image more. Dutch scientist Antoine van Leeuwenhoek designed high-powered single lens microscopes in the 1670s. With these he was the first to describe sperm (or spermatozoa) from dogs and humans. He also studied yeast, red blood cells, bacteria from the mouth and protozoa. Van Leeuwenhoek’s single lens microscopes could magnify up to 270 times larger than actual size. Single lens microscopes remained popular well into the 1830s, as all types of microscopes improved.
Scientists were also developing new ways to prepare and contrast their specimens. In 1882, the German physician Robert Koch presented his discovery of Mycobacterium tuberculosis, the bacilli responsible for tuberculosis. Koch went on to use his staining technique to isolate the bacteria responsible for cholera.
The very best microscopes were approaching a limit by the beginning of the 20th century. A traditional optical (light) microscope can’t resolve objects smaller than the wavelength of visible light. But in 1931, German scientists Ernst Ruska and Max Knoll overcame this theoretical barrier with the electron microscope.
Ernst Ruska was born the last of five children on Christmas Day 1906, in Heidelberg, Germany. He studied electronics at the Technical College in Munich and went on to study high voltage and vacuum technology at the Technical College of Berlin. It was there that Ruska and his adviser, Dr. Max Knoll, first created a “lens” of a magnetic field and electrical current. By 1933, the pair built an electron microscope that could surpass the magnifying limits of the optical microscope at the time.
Ernst won the Nobel Prize in Physics in 1986 for his work. The electron microscope could achieve much higher resolution because an electron’s wavelength is smaller than the wavelength of visible light, especially when the electron is sped up in a vacuum.
Both electron and light microscopy advanced in the 20th century. Today, labs may use fluorescent tags or polarized filters to view specimens, or they use computers to capture and analyze images that wouldn’t be visible to the human eye. There are reflecting microscopes, phase contrast microscopes, confocal microscopes and even ultraviolet microscopes. Modern microscopes can even image a single atom.
