Differences between light and electron microscope

A microscope is an optical instrument that allows you to appreciate very small elements and objects in a larger size, in order to be able to observe their details and physical characteristics that, due to their small size, are difficult to observe with the naked eye.

There are two types of microscopes: the light microscope and the electron microscope. In this sense, in this article we will present the differences that exist between each of them, based on their definitions.

Optical microscope

The optical microscope is a microscope that, as its name suggests, is based on optical lenses. It is also known as a light microscope, since it uses light or “photons” or a bright field microscope. This is an instrument that has more than one objective lens and is used to examine transparent objects or very thin plates through a system of lenses and light sources.

Therefore, in the light microscope, the magnification of the object is achieved by using a lens system that manipulates the passage of light rays between the object and the eyes. Its history dates back to the year 1608 when Zacharias Janssen built a device with two converging lenses, which had the function of enlarging the objects placed under his lens.

Over the years, various scientists incorporated new ideas to the original to perfect the apparatus until in 1952 a Polish physicist named Georges Nomarski designed the differential interference contrast system for the light microscope, giving rise to the optical microscope that until today It is widely used in the field of biology.

Next, the optical microscope is made up of two parts, a mechanical system composed in turn of parts such as support, stage, head, revolver and focus screws that constitute the mechanical or physical parts of the apparatus and an optical system formed by the eyepiece, the objective, the condenser, the diaphragm and the focus, parts whose function is to regulate the amount of light and direct the light rays towards the condenser to enlarge the image of the objective.

Electronic microscope

The electron microscope is one that uses electrons instead of photons or visible light to form images of tiny objects. In this sense, in the most modern electronic microscopes, images of up to 5000 times more magnified than with the higher range optical microscopes can be seen, because the wavelength of the electrons is much shorter than that of the visible photons. .

Its history dates back to 1925 when Ernst Ruska and Max Knoll, based on Louis-Victor de Broglie’s studies on the wave properties of electrons, applied certain formulas for the design of the device. There are two main types of electron microscopes: the transmission electron microscope and the scanning electron microscope. The transmission electron microscope is the one that uses a beam of electrons that is projected towards the object to be enlarged and the scanning electron microscope is the one that covers the sample with a layer of thin metal and is swept with electrons that are emitted from a cannon to later be shown on a screen.

The energy source of an electron microscope is a beam of electrons, its lens system is made of electromagnets, the image is projected on the screen and through it only dead cells and inert material can be observed.

According to the above, the following differences between optical microscope and electron microscope can be pointed out:

Optical microscope Electronic microscope
In an apparatus based on optical lenses. It is a device based on the properties of electrons.
Its energy source is visible light. Its energy source is a beam of electrons.
Its lens system is made of glass or quartz crystals. Its lens system is made of electromagnets.
The image is observed directly. The image is observed from the projection on a screen.
It is used to observe living cells. It serves to observe dead cells and inert matter.

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