These are the simplest and oldest microscopes which use light along with powerful lenses to focus on a living or a dead specimen placed onto a platform called the stage (refer to the picture above). The specimen (also called sample) is viewed using the eye piece.
Before we move onto electron microscopy we must understand what exactly is meant by the term resolution. Resolution is a measure of how detailed an image is. A picture with a great resolution is very clear. The problem with light microscopy is that the image (called micrograph) formed using a light microscope has a lower resolution i.e. it is less clear even at the highest magnification. Now the question is why resolution matters. It matters because the clarity of an image matters when viewing cells that have very small parts if the resolution is low then two small parts can end up appearing as one single small part. Light microscopes have a limit of resolution of 200nm that is if any two objects are viewed using a light microscope and are closer than 200nm to each other than they
cannot be viewed as separate objects and instead they get merged into a single object. The major difference between a light and an electron microscope is of resolution. Electron microscopes have a much greater resolution than light microscopes and as a result the image (micrograph) obtained using an electron microscope is much clearer.
These use a beam of electrons (very small negatively charged particles that are found in all substances) instead of light to examine the specimen. Electron microscopes were made in order to overcome the limitations of the light microscope. Electron microscopes provide much larger magnification and much clearer images of specimen being viewed. There are two types of electron microscopes:
1. Scanning electron microscope (SEM) designed after reflective light microscopes these are also using electrons beams but here the beam is used for scanning the surface or the boundary of