Under a Light microscope is understood to be an instrument with which the smallest structures can be clearly represented. These are enlarged accordingly by the action of lenses.
What is a microscope?
Using a light microscope, it is possible to enlarge images extremely. The smallest objects, organisms or living beings can be easily recognized by the human eye by zooming in. The light microscope achieves the magnification through different optical effects.
The term light microscope includes the ancient Greek terms “micron” and “skopein”. In the German translation this means “look at something small”. The light microscope has the property of enlarging the objects to be examined by exposure to such a degree that the observer can look at them.
Magnifying lenses were used as early as the 16th century. The physiological principles for the light microscope, which are still valid today, were developed around 1873 by the German physicist and optician Ernst Abbe (1840-1905). They made it possible to construct more efficient microscopes. So now the production of lenses took place, the resolution limit of which was no longer determined by the quality of the material, but instead by the laws of physical diffraction. The physical resolution limit was given the name Abbe limit. The corresponding microscopes were manufactured in the optical workshops of Carl Zeiss (1816-1888).
Shapes, types & types
The light microscope can be divided into several types. For example, there is the reflected light microscope, in which the light comes from the same side on which the observation is made. It is mainly used in fluorescence microscopy and for examining opaque objects.
Another form is the stereomicroscope, which has separate beam paths for both eyes. In this way, the object can be viewed from several angles, which gives a three-dimensional impression.
The surgical microscope is used by doctors specifically when performing surgical interventions, while the trichinoscope is used for examinations with which trichinae (roundworms) can be detected.
A measuring microscope is a light microscope that is equipped with an additional device with which objects can be measured. The computer microscope is a modern variant. A USB cable is used to connect it to a computer that displays the image of the object.
A distinction must also be made between simple and compound light microscopes. Simple microscopes have optical lenses through which a high magnification is achieved. There is a smooth transition to the magnifying glass, the principle of which works in the same way, whereby its magnification is significantly weaker.
Nowadays, compound light microscopes are mainly used. They consist of two lens systems. The lens, which marks the foremost optical element, creates an intermediate image. The renewed enlargement of this image takes place through the eyepiece.
Structure & functionality
A light microscope is built from the lens system, the eyepiece, objectives, a deflecting prism, a tube and a tube carrier. Furthermore, the microscope has a so-called objective nosepiece at its upper end. The objectives are available on this revolver, which can be selected and locked using a rotating wheel. An object table and object clamps are used to present an object to be examined. In its sub-area, the light microscope is also equipped with a light source, a diaphragm and a condenser.
To give the light microscope stability, it is supported by a foot. The foot can be used to move or lift the instrument. With the help of the aperture, the user sets the optimal exposure for the object being examined. The shutter can be opened or closed using the control slide. The light radiation is bundled with the condenser and directed onto the object.
The microscope's light sources are usually located on its base. This can be a mirror that makes sunlight usable for microscopy. However, electric lamps are considered more uniform and reliable.
The objective of the light microscope has the effect of a converging lens. It enlarges the image to be examined and, in a first step, creates an intermediate image in the tube. In the second step, the eyepiece, which acts like a magnifying glass, significantly enlarges the intermediate image. With this method, a light microscope can produce magnifications of up to 1400 times.
The function of the light microscope is based to a certain extent on viewing an object in the backlight. The light begins at the light source on the underside of the microscope. The object is penetrated by light, which results in an intermediate image in the tube through the objective, which is then enlarged by the eyepiece.
Medical & health benefits
The light microscope is one of the most important medical instruments. Numerous fundamental scientific questions could be cleared up with the microscope. In addition, it made important modern developments possible in medicine.
In medical use, the light microscope is mainly used to assess microorganisms, body cells, blood components or tissue samples. Before carrying out special therapies, it is often essential to determine the causative germs such as bacteria or fungi under the microscope. The exact detection of the pathogen is also possible with the light microscope. A laboratory examination of samples such as blood, pus or wound secretions is carried out, through which the responsible bacterium can be precisely identified.
A disadvantage of the light microscope, however, is that it can hardly detect viruses. An electron microscope is better for this purpose. The light microscope also plays an important role in microsurgery and in minimally invasive surgical interventions.
