1. As is the case with many other technological devices, microscopes have a very long history. By the 1st century, glass had been invented and the Romans had started experimenting with different sizes and shapes to observe objects. The earliest simple microscopes were simply magnifying glasses with low power (6x to 10x). These microscopes were referred to as flea glasses since they were mostly used for the purposes of observing tiny insects such as fleas.
2. Optical microscopes were developed between the 1590s and 1660s. This simple compound microscopes used two lenses and relied on the natural light to observe the sample. These types of microscopes were developed by such individuals as Zacharias and Han Jensen and Anton van Leeuwenhoek among others and could be used to observe much smaller samples. For instance, Anton van Leeuwenhoek used his microscope to observe bacteria in a drop of water.
3. In 1665, Robert Hooke used a simple compound microscope to observe a wide range of objects. On examining the surface of a cork, Hooke observed pore, but did not know that he had discovered plant cells. Hooke simply called these pores cells.
4. From the 1660s, there were very little changes in the development. For this reason, for over 200 years, microscopes remained relatively the same despite their imperfections until the 1850s, when Carl Zeiss, a German engineer began to make improvements on the device.
5. Spherical aberration refers to the unequal bending of light hitting different parts of a lens. The problem of spherical aberration was solved by Joseph Jackson Lister in 1830 when he discovered that by placing lenses at a given distance from each other, aberration from all by the first lens could be eliminated.
6. Given that the optical limits have been reached, the development of microscope has slowed down with a majority of the light microscopes following the same structural principles that describe monocular, binocular and stereo-binocular microscopes.
1. Microscopes have greatly contributed to modern medicine. Before the development of microscope, the general belief was that illnesses and diseases were caused by evil spirits or poisonous gases. However, the invention of microscopes helped in the observation of bacteria and other microorganisms, which in turn helped in the development of appropriate cures.
2. Binocular microscopes have a prism, which is either in the microscope head or body tube. The prism serves to split the image, directing it to both oculars.
3. When looking through the microscope oculars, the observer does not see the specimen itself, but rather the image of the specimen, which is projected by the lenses to the location below the eyepiece.
4. After observation of cells for several decades using a microscope, Matthias Schleiden and Theodor Schwann developed the cell theory, which states that:
a) All living things are made up of cells
b) Cells are the basic units of structure, function and physiology
c) Living cells can only come from pre-existing cells
5. Here, it is important to note that nothing about cells was known before the invention of microscopes.
6. A 500 nanometer long object is the smallest sample that can be clearly observed under the light microscope. While smaller objects can be observed, it is difficult to clearly discern them using a light microscope because of the wave nature of light used.
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