History Of Light Microscopes

Antony van Leeuwenhoek (1632-173) was responsible for on of the earliest developments of the microscope, it consisted of a powerful convex lens and an adjustable holder for the object being studied. This instrument would have been able to magnify objects up to 400x and with it he discovered protozoa, spermatozoa, and bacteria, and was able to classify red blood cells by shape. The limitation with this microscope was the single convex lens. This was fixed by the addition of a second lens, giving rise to the compound microscope which is the basis of light microscopes today.

During the 18th century, technology developed into using a beam of electrons for the microscope unit to improve resolution capabilities. The first electron microscope was

A significant amount of training and specialized skill is required in order to successfully operate either of them. Similarly there exists many differences between these microscopes. The method used in SEM is based on scattered electrons while TEM is based on transmitted electrons. The scattered electrons in SEM are classified as backscattered or secondary electrons. However, there is no other classification of electrons in

In TEM, electrons are directly pointed toward the sample. The electrons that pass through the sample are the parts that are illuminated in the image.

The focus of analysis is also different. SEM focuses on the sample’s surface and its composition. On the other hand, TEM seeks to see what is inside or beyond the surface. SEM also shows the sample bit by bit while TEM shows the sample as a whole. SEM also provides a three-dimensional image while TEM delivers a two-dimensional picture.

In terms of magnification and resolution, TEM has an advantage compared to SEM. TEM has up to a 50 million magnification level while SEM only offers 2 million as a maximum level of magnification. The resolution of TEM is 0.5 angstroms while SEM has 0.4 nanometers. However, SEM images have a better depth of field compared to TEM produced images.

Another point of difference is the sample thickness, “staining,” and preparations. The sample in TEM is cut thinner in contrast to a SEM sample. In addition, an SEM sample is “stained” by an element that captures the scattered