Question

Compare and contrast the structure and function of a compound light microscope and a scanning electron microscope. Be sure to discuss the structure and function of each as well as the function and usefulness of each when examining a specimen

Answer 1

Scanning Electron Microscope, or SEM: This electron microscope is quite different from the Transmission Electronic Microscope. In this, the image of the specimen is not created by using electrons directly. Instead, electrons are used in such a manner as to excite it, so that it gives off secondary electrons, which detectors collect and use to create an image. Most images that are seen in books and articles are secondary electron images. However, apart from the generating secondary electrons, the beam also results in scattering them as well. An image can also be formed from these backscattered electrons. As a matter of fact, there are several beam interactions of the specimen which create useful information. For instance, the electron beam can also cause X-Rays to be emitted by the specimen. A separate detector can collect these, which can be used to study the elemental components that the specimen is made up of, or can also be used for creating the specimen's elemental map on a video screen.


A compound microscope can be used for several purposes ranging from medical research to a day at the beach as your urge to know can only be inhibited by your imagination. Like every field of knowledge it is first necessary to know the basics and then remember them as and how you keep working on it.

There are few basic functions that are same for every microscope. For every microscope to work there has to be a light source that would help to illuminate the object that has to be seen.
The source of light can either be a mirror, which would reflect light from outside, or the device has to have a light source of its own.
When light passes through the object, the lens that is nearest to the object will help to produce a magnified image of the specimen that is to be seen. The lens that is nearest to the object is called objective lens.
The lens through which you look into the microscope is a kid of magnifying glass and helps to an extent to produce an enlarged image of that image that is already magnified by the objective lens of the specimen that is being viewed.
So the magnification extent can be calculated by multiplying the power of the objective lens and the magnifier.
A compound microscope can magnify things up to 2000x, not more than that but then image larger than that neither our eyes would be able to recognize nor our brains would be able to read.


Parts of a Compound Light Microscope

A compound light microscope has an eyepiece, stage clips which hold the slide in place, objectives that consist of different lenses, Adjustment knobs, power switch and a stage where the slides are kept and below it is at the source of light that is inbuilt in a compound light microscope. There are other parts also like a Diaphragm, base, body tube; nose piece, aperture, arm and stage stop which helps to determine that height of the stage - all these parts facilitate the closer and clearer viewing of the object through the Compound Light Microscope.

Uses of a Compound Microscope

A compound Microscope is nowadays used in several fields of sciences like the Microbiology, Botany, Geology, Genetics and the like. Forensic experts and scientists can also find out the country from which the drug has come by viewing its particles under a compound microscope as the shape of the crystals can give a reference as to which country the opium was grown in. Microscopes also help in looking at the minute details of the human cells and determine the presence or absence of minerals, identify the presence of metals, thus solve crimes and discover medicines.