🔬The microscope🔬

🔬History of the microscope🔬

The desire to know new things is a characteristic of man, which conforms us to what he can see with his own eyes. He has always been interested in other objects that he cannot observe directly, which is why he has made devices that allow him to see objects that are very far away, those that are very small. Nature helps man in his endeavor. A simple drop of water on a book increases the size of the letters.

The first attempt to achieve a device that allows observing very small objects dates back to António Leewenhook (1632-1723) who, through well-polished lenses, managed to discover the microscopic world. The microscope was born.

🔬Parts of a microscope🔬

We can distinguish two functional parts: optical part and mechanical part.

• Optical part: the fundamental part of the microscope is made up of two lenses: the eyepiece and the objectives.
The eyepiece is the lens that is close to the eye. Increases the size of the image of the object to be observed. The eyepiece is inserted or supported in the eyepiece tube.

The objective is the lens that is close to the object that you want to observe. It also increases the image of the object.

Both the eyepiece and the objective have a number that indicates the magnification they produce. By multiplying the magnification of the objective by that of the eyepiece, we obtain the magnification produced by the microscope.

The light is used and directed by the mirror to the preparation or object of our observation.

The light input is regulated by the diaphragm and concentrated on the object by the condenser.

• Mechanical part: the object to be observed is placed on a glass slide, which is mounted on the stage or flat surface that has a central hole to let light through. The slide can be moved thanks to the carriage, to the right and left, forwards and backwards.

The revolver allows you to choose the target required for observation. The screws are used to adjust the distance between the objective and the preparation to focus the microscope. There are two screws:
The coarse screw allows fast focusing movements, while the fine screw does it slowly.

🔬Types of microscopes🔬

There are different classes of microscopes, depending on the nature of the light systems, and other accessories used to obtain the images.

🔸The compound or optical microscope uses lenses to magnify the images of the objects observed. The magnification obtained with these microscopes is low, due to the wavelength of visible light that imposes limitations.

The optical microscope can be monocular, and consists of a single tube. Observation in these cases is done with a single eye. It is binocular when it has two tubes. Observation is done with both eyes.

This has advantages such as better image perception, more comfortable observation and details are perceived more clearly.

🔸Stereoscopic microscope, the stereoscopic microscope makes possible the three-dimensional vision of the objects. It consists of two eye tubes and two pairs of objectives for each magnification.

This microscope offers advantages for observations that require small magnification.

The optimum for stereoscopic vision is between 2 and 40x or full microscope magnification.

🔸Dark-field microscope, this microscope is equipped with a paraboloid condenser, which means that the light rays do not penetrate directly into the objective, but rather obliquely illuminate the preparation.

Objects appear as bright spots on a dark background.

🔸Fluorescence microscope, fluorescence is the property that some substances have of emitting their own light when energetic radiation hits them.

Treatment of biological material with fluorochromes facilitates microscopic observation.

🔸Phase contrast microscope, is based on the modifications of the path of light rays, which produce remarkable contrasts in the preparation.

🔬Microscope handling🔬

I placed the slide containing the preparation on the microscope stage, taking care that the preparation remained on the hole in the stage.

Look through the eyepiece and with the mirror try to focus the light on the preparation. Looking out, lower the objective until it touches the slide and then looking through the eyepiece, slowly move the coarse screw until the preparation appears. Then use the micrometer screw to sharpen the focus of the preparation.

• Care of the microscope, the microscope is a valuable instrument, therefore it must be kept clean, especially the lenses of the eyepieces and objectives. It must be protected from moisture dust. Keep away from acids and substances that could affect lenses and mechanical parts.

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