A microscope is a scientific instrument that makes things that are too small into big so that they can be examined correctly. A Simple microscope is a microscope that uses only one lens for magnification. It is the original design of the light microscope. Van Leeuwenhoek’s microscopes consisted of a small single converging lens mounted on a brass plate with a screw mechanism to hold the sample or specimen to be inspected. Even though it is now considered prehistoric, the use of a single, convex lens for viewing is still found in simple magnification devices, such as magnifying glass and the loupe. People who generally use microscopes are Doctors and Scientists.
One of the initial uses of microscopes for examining the minute details of living things was by Dutch cloth merchant, Anton Van Leeuwenhoek (1632-1723). His microscope was very simple but the way he ground the lenses made it popular and easy to handle than the compound microscopes used before. He was able to study the structure of tissue and was one of the first scientists to determine protozoa present in water. He also worked on the anatomy of circulation, by finding the blood carrying capillaries. His microscope was considered to be of superior quality in those days. Leeuwenhoek’s microscope consisted of a screw for adjusting the height of the object being examined, a metal plate serving as the body, a skewer to run through the object and rotate it and a spherical lens. The first successful compound microscope was build by Zacharias Janssen, a Holland native, whose microscope consisted of 2 lenses and was over 6 feet long. By 19th century, optics was perfected but the basic design remains same till today.
There are many types of microscopes. The most common are Compound light microscope, Electron microscope, and Laser microscope.
A microscope works much like a refracting telescope but with minor differences. A telescope must gather a large amount of light from a dim, distant object and so it needs a large objective lens to gather as much as light as possible and bring it to a bright focus. Since the objective lens is large, it brings the image of the object to a focus at some distance away which is why telescopes are much longer than microscopes.
In contrast to a telescope, a microscope must gather light from a tiny area of a thin, well-illuminated specimen that is close-by. So, a microscope does not need a large objective lens and so it is small and spherical. It has much shorter focal length on either side. It brings the image of the object into focus at a shorter distance within the microscope’s tube. The image is then magnified by the second lens known as ocular or eyepiece as it is brought to the eye. A microscope has a light source and a condenser. The condenser is a lens system that focuses the light from the source onto a tiny bright spot of the specimen. Microscopes have interchangeable objective lenses and fixed eyepieces.