How Much Do You Know About A Microscope?

One of the most common an important devices inside any kind of laboratory is the microscope. This ancient instrument has become a fundamental device to have in the biological and medical field. There are different types of microscopes. To choose the appropriate microscope according to your needs, it is essential to know their basic components and types.

Components of the microscope

Eyepiece lens or ocular: These are the lens at the top of the microscope that people use to look through. The researcher places the eye at the exit pupil of the eyepiece and eyepieces vary from 5x-30x.

EyepieceTube: It connects the eyepiece to the objective lenses and assures the alignment of the optics. Its length is standardized, related to the distance between the height of the tabletop and the position of the observer, 160mm. Binocular microscope heads usually have a diopter adjustment ring in case of inconsistencies of eyesight in one or both eyes.

Arm: It is used to support the tube and connect it to the base f the microscope.

Base: It is the support of the microscope.

Stage: this is the flat platform where the slides are placed and it holds them in one piece.

Turret: It holds and rotates the objective lenses to magnify the image.

Objective lenses: It is the group lenses closer to the object being viewed. Usually there three to four 4 lenses in a microscope with a variety of range from4x-100x and typically. Objectives can be forward or rear-facing.

Illuminator: the standard illumination transmits light through a translucent object for viewing. The illuminator is a steady light source used to reflect light from an external light source up through the bottom of the stage. Modern microscopes have a light source as an electric lamp or a diode, instead of a mirror.

Rack stop: This part can adjust how close the objective lens can get to the slide being viewed.

Condenser lens: It focuses the light on the slide being viewed.

Diaphragm: It is located under the stage and it adjusts the intensity and the size of light projected through the slide.

Coarse and Fine Focus knobs: are used to focus the microscope.

The stage: It is where the specimen is placed to be viewed.

Stage Clips: in case there is no mechanical stage, stage clips are used instead and it facilitates the view of different sections of the specimen.

Aperture: it is a hole in the stage through which light reaches the stage.

Condenser: it is located under the stage and in conjunction with an iris diaphragm collects and focus the light from the illuminator on to the specimen.

Types of Microscopes

There are different ways to categorize a microscope. These are just some general types widely used in laboratories

Monocular: a compound microscope with one eyepiece. It is widely used in education due to the fact that it is easy-to-use and pretty standard. However, it has a low resolution in contrast to the rest of the models.

Binocular: It is a type of microscope with two eyepieces that allow the reduction of the ocular tension. There is a prism that divides the light in two equal beams of light projected towards both oculars.

Trinocular: It is a binocular microscope with a third lens for connecting a microscope camera while the observation is taking place.

Inverted microscope: it is a trinocular microscope with its light source and condenser on the top, above the stage pointing down, while the objectives and turret are below the stage pointing up. This type of microscope is suitable for the study of sells or organism at the bottom of a large container, close to natural conditions.  It has also metallurgical applications.

Dark-field microscope: can be binocular or trinocular and they that have a special condenser and objective with a diaphragm or stop that scatters light from the object observed, with the result that the object appears bright on a dark background.

Phase contrast microscope: It has special condensers that allow the light to pass through the specimen at a different speed. It is useful to the study of live, unstained organism.

Metallurgic: they are used to inspect materials such as metals, ceramics, and other materials. The most common metallurgical microscopes are acoustic or ultrasonic microscopes that can be used to examine delimitations, cracks and other anomalies.

Digitals: this type of microscope does not have an eyepiece to look at the sample, but it outputs the image to a monitor, by means of software running on a computer. Most of the times it has its own built-in LED light source.

Electron microscope: It uses a beam of accelerated electrons as a source of illumination. They have a better resolving power than light microscopes and are capable of revealing the structure of smaller objects such as microorganisms, cells, large molecules, biopsy samples, metals. They are often used for quality control and failure analysis. It is also used in medical research and nanotechnology.

Fluorescence microscope: It uses fluorescence and phosphorescence to reveal the image.  When the ultraviolet light hits an object, the electrons are excited and the result is various shades of the colour. it is used to study the properties of organic and inorganic substances and in the study of unknown bacteria.

Stereo Microscope: This type of microscope is designed for low magnification of the sample. It is a binocular microscope with two objectives and eyepieces that along with the two separated optical paths allow slightly different viewing angles to the left and right eyes, producing a three-dimensional visualization of the sample being examined. It is the ideal microscope for dissection, inspection, manufacturing or when using an opaque specimen. It is widely used by amateurs, professional and industries, but not in scientific research.

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