The main optical microscope parts are the foot, tube, revolver, column, platinum, carriage, micrometric and macrometric screw, eyepieces, lens, condenser, diaphragm and transformer.
The optical microscope is a microscope based on optical lenses which is also known by the name of light microscope or light field microscope. It can be monocular or binocular, which means it can be watched with one eye or two.
With the use of a microscope we can amplify the image of an object through a system of lenses and lighting sources. Manipulating the passage of a ray of light between the lens and the object, we can see the image of this amplified.
It can be divided under a microscope into two parts; The mechanical system and the optical system. The mechanical system is how the microscope is built and the parts where the lenses are installed. The optical system is the lens system and how they manage to amplify the image.
The optical microscope generates an enlarged image using several lenses. Firstly, the lens of the lens is an enlargement of the actual magnified image of the sample.
Once we get that enlarged image, the eyepiece lenses form an extended virtual image of the original sample. We also need a spot of light.
In optical microscopes there is a light source and a condenser that focuses on the sample. When the light has passed through the sample, the lenses are responsible for increasing the image.
Parts and Functions of the Optical Microscope
Mechanical system
The foot
It is the base of the microscope and its main support, can have different forms, being the most usual rectangular and Y-shaped.
The tube
It has a cylindrical shape and inside it is black to avoid the discomfort of the reflection of light. At the end of the tube is where to place the eyepieces.
The revolver
It is a rotating piece in which the objectives are screwed. When rotating this device, the objectives pass through the axis of the tube and are placed in working position. It is called stirring by the noise made by the pinion when it engages in a fixed place.
The spine
The column or arm, in some cases known as a handle, is the part of the back of the microscope. Attached to the tube at the top and at the bottom is attached to the foot of the apparatus.
Platinum
The platen is the flat metal part on which the sample to be observed is placed. It has a hole in the optical axis of the tube that allows the ray of light to pass in the direction of the sample.
The platen can be fixed or rotating. If it is rotating, by means of screws it can be centered or moved with circular movements.
The car
It allows to move the sample with an orthogonal movement, forwards and backwards, or from right to left.
The macrometric screw
The device attached to this screw causes the tube of the microscope to slide vertically thanks to a rack system. These movements allow you to quickly focus the preparation.
The micrometric screw
This mechanism helps to focus the sample with an accurate and sharp focus through the almost imperceptible movement of the platen.
The movements are through a drum having divisions of 0.001 mm. And that also serves to measure the thickness of the coupled objects.
Parts of the optical system
Eyepieces
They are the lens systems closest to the observer's eye. They are hollow cylinders at the top of the microscope provided with converging lenses.
Depending on whether there is one or two eyepieces, microscopes can be monocular or binocular
goals
They are the lenses that are regulated by the revolver. They are a system of convergent lenses in which several objectives can be coupled.
The coupling of the lenses is done in an increasing manner according to their increases in the clockwise direction.
The targets carry their increase on one side and are also distinguished by a colored ring. Some of the objectives do not focus on preparation in the air and need to be used with immersion oil.
Condenser
It is a convergent lens system that captures light rays and concentrates them in the sample, providing more or less contrast.
It has a regulator to adjust the condensation through a screw. The location of this screw may vary depending on the microscope model
Lighting source
The illumination is constituted by a halogen lamp. Depending on the size of the microscope may have higher or lower voltage.
The smallest microscopes used in laboratories have a voltage of 12 V. This illumination is at the base of the microscope. The light exits the bulb and passes to a reflector that sends the rays in the direction of the plate
Diaphragm
Also known as iris, it is located on the reflector of light. Through this the intensity of the light can be regulated by opening or closing it.
Transformer
This transformer is necessary to plug the microscope into the electric current since the power of the bulb is less than the electric current.
Some of the transformers also have a potentiometer that regulates the intensity of light passing through the microscope.
All parts of the optical system of microscopes are made up of corrected lenses for chromatic and spherical aberrations.
Chromatic aberrations are due to the fact that light is composed of radiation that undergoes an unequal deviation.
Achromatic lenses are used so that the colors of the sample are not changed. And the spherical aberration occurs because the rays passing through the end converge at a closer point, so a diaphragm is placed to allow the passage to the rays in the center.
References
- Page 1 History of Microscopy. Introduction to Biology. Fac. Of Exact and Natural Sciences , 2001.
- NIN, Gerardo Vázquez. Introduction to electron microscopy applied to biological sciences . UNAM, 2000.
- PRIN, José Luis; HERNÁNDEZ, Gilma; OF GASCUS, Blanca Rojas. OPERATING THE ELECTRONIC MICROSCOPE AS A TOOL FOR THE STUDY OF POLYMERS AND OTHER MATERIALS. I. THE ELECTRONIC SWEEP MICROSCOPE (MEB). Ibero-American Polymer Magazine , 2010, vol. 11, p. 1.
- AMERISE, Cristian, et al. Morphostructural analysis with optical and electron microscopy of human tooth enamel on occlusal surfaces. Venezuelan Dental Act , 2002, vol. 40, paragraph 1.
- VILLEE, Claude A.; ZARZA, Roberto Espinoza; And CANO, Gerónimo Cano. biology . McGraw-Hill, 1996.
- Piaget, Jean. Biology and knowledge . 21st Century, 2000.