A microscope is a tool to see objects that are too small and cannot be seen with the naked eye. The microscope comes from the Greek, micros (small) and scope (to see).
The science that studies small objects using this tool is called microscopy, while microscopic means very small and not easily seen by the eye.
Types of Microscopes
The first type of microscope and the most common type is the optical microscope. This microscope is an optical instrument consisting of one or more lenses. This lens produces an enlarged image of an object stored in the focal plane of the lens.
Microscopes are divided into two based on the light source.
1. Light
Microscope This microscope is known as a compound light microscope and is a microscope that uses light instead of sunlight. Meanwhile, the light source in conventional microscopes still comes from sunlight reflected by a flat or concave mirror under the condenser. Furthermore, this mirror will direct light from outside into the condenser.
Types of Lenses
There are three types of lenses used by light microscopes, namely objective lenses, eyepiece lenses, and condensers.
The objective lens serves to form the first image, determining the structure and microscopic parts that will be visible in the final image. In addition, this lens is also able to enlarge the image of the object so that it can have an "aperture" value.
The value of "aperture" is a measure of the refractive power of an objective lens that will determine the power of separation of the specimen so that it can show microscopic structures in close positions as two separate objects.
The ocular lens is located at the upper end of the tube and close to the eye of the observer. This lens serves to enlarge the image produced by the objective lens.
The condenser lens functions to support the creation of lighting on the object to be seen. With the appropriate settings, maximum separation will be produced.
2. Electron
Microscope This microscope can magnify objects up to 2 million times.
This microscope uses electrostatics and electromagnets to control lighting and image display and can magnify objects better than a light microscope.
The types of electron microscopes, including the following.
a. Transmission Electron Microscope (TEM)
The TEM is an electron microscope that works in much the same way as a slide projector. The way it works is that electrons are penetrated into the object of observation and the observer observes the results of the penetration on the screen.
b. Transmission Electron Scanning Microscope (STEM)
STEM is a type of transmission electron microscope (TEM) developed. In this type, electrons penetrate the specimen and the electron optics focus directly at a narrow angle by scanning the object using a scanning pattern.
This object is scanned from one side to the other (raster) and produces rows of dots that make up an image like on a television.
c. Scanning Electron Microscope (SEM)
This microscope is used to study the detailed architecture of cell surfaces and objects observed in three dimensions. In scanning electron microscopy, an image is created based on the detection of new electrons (secondary electrons) or reflected electrons that appear on the surface of the sample when it is scanned with an electron beam.
Secondary electrons are detected, the signal will be amplified. Then, the magnitude of the amplitude is shown in dark-light gradations on the CRT (Cathode Ray Tube) monitor screen. It is on this screen that an enlarged image of the object's structure can be seen.
Microscope Structure
There are two main parts in the microscope structure.
The optical part consists of a condenser, objective lens, and eyepiece.
The non-optical part consists of the legs and arms of the microscope, the diaphragm, the object table, the smooth and rough dial, the object glass clamp, and the light source.
Magnification
Casting an image of an object in a larger microscope is the goal of light and electron microscopy. This magnification depends on several factors, including the focal point of the two lenses.
Properties of Image
The objective and eyepiece lenses are convex lenses. The objective lens produces a temporary and false image, inverted, and enlarged with respect to the initial position of the object. Then, the eyepiece determines the nature of the final image.
The final image in a light microscope has the same properties as the temporary image. Meanwhile, the final image on the electron microscope has the same properties as the real object (aligned and magnified). If you put the letter A under a light microscope, you will see an inverted and enlarged letter A.
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