The microscope is one of the most important medical instruments. Thus, it is indispensable for the diagnosis of numerous diseases.
What is a microscope?
The microscope is among the most important medical instruments. With the help of a microscope, very small objects can be magnified to such an extent that they can be visualized. Usually, the objects to be examined are at a size that is below the resolving power of the human eye. The technique in which the microscope is used is called microscopy. The microscope is particularly important in medicine for carrying out various examinations. In addition, it is also used in biology and material sciences. Basically, the microscope is one of the most important inventions of mankind. Thus, a variety of scientific and medical questions could be clarified with the help of this instrument. The term microscope or microscopy comes from ancient Greek. While Mikros translated German means “very small”, Skopie stands for “look at”.
Forms, types and species
A distinction is made between different types of microscopes. These are the light microscope, the electron microscope as well as the scanning probe microscope. The oldest and best known technique represents the light microscopy. It was started around 1595 by Dutch spectacle grinders and lens technicians. In light microscopy, objects are viewed through one or several glass lenses. The maximum resolution of a classical light microscope depends on the wavelength of the light used. There is a limit of about 0.2 micrometers. The name for this limit is the Abbe limit. This is how the German physicist Ernst Abbe (1840-1905) described the corresponding laws. From the 1960s onwards, microscopes were also developed that went beyond Abbe’s resolution limits. Even higher resolution is possible with the help of electron microscopes. These instruments were manufactured in the 1930s. The inventor of the electron microscope was the German electrical engineer Ernst Ruska (1906-1988). Electron beams have a shorter wavelength than light, allowing for more precise observation. In this way, medicine as well as biology had even better examination possibilities at their disposal, as they could use an electron microscope to examine objects where this was no longer possible with a light microscope. These include viruses, prions, chromatin and DNA. Another microscope variant is the atomic force microscope. It was developed in 1985 by Gerd Binnig, Christoph Gerber and Calvin Quate. This special scanning probe microscope is equipped with fine needles that are used to scan surfaces. Its operation is therefore based on a different principle. The use of light microscopes, scanning probe microscopes and electron microscopes takes place in numerous different variants. For example, there is the magnetic resonance microscope, the X-ray microscope, the ultrasound microscope, the neuron microscope as well as the helium ion microscope.
Structure and operation
The structure of a conventional microscope consists of a stand attached to a heavy base that provides stability for the instrument. The generation of light takes place on the bottom with an electric light source or a mirror. With the aid of an adjustable diaphragm, known as a condenser, the light can be directed from below through an opening located in the specimen stage onto the specimen slide. The object to be examined is placed in the object slide. To prevent image blurring, two metal clamps provide stability for the slide. Another important component of the microscope is the optical apparatus. This includes various objects with several magnification factors, which are located on the revolving turret. The magnification is usually 4x, 10x or 40x. In addition, 50x as well as 100x objectives are also available. With the help of a mirror, which is placed in the tripod, the light finds its way to the tube. It then falls into the eyepiece through which the object can be viewed. The operation of a light microscope is done by viewing the object in backlight.The light, which is also referred to as the light path, starts at the light source under the object carrier. The object is penetrated by the light, resulting in a real intermediate image with the objective inside the tube. The eyepiece of the microscope acts like a magnifying glass, again producing a significantly magnified virtual intermediate image.
Medical and health benefits
For medicine, the use of the microscope is of fundamental importance. It is primarily used to evaluate tissue samples, microorganisms, blood components, and cells. In particular, the identification of pathogens such as bacteria or fungi is often indispensable in order to carry out appropriate therapy. With the aid of microscopic examinations, physicians can detect certain pathogens. For this purpose, infected samples such as blood, wound secretions or pus are examined under a light microscope to determine the causative bacterium. However, viruses can hardly be detected with a light microscope. This is only possible with an electron microscope. Microscopic examinations also play an important role in the early detection of cancer. In this case, tissue samples taken from a biopsy or a cell smear are examined with the instrument to clarify a suspected cancer. But the microscope also provides valuable information after surgical removal of the tumor. Among other things, it can be used to determine the type of cancer involved and whether the tumor is aggressive or rather slow-growing. Special medical examinations with the microscope are performed in pathology laboratories that specialize in these diagnostics.
