The basic optical microscope is an invaluable tool, and one which has principles which were discovered hundreds of years ago and have advanced remarkably little. By bending light, objects can be made to appear larger, or smaller. As you near the atomic level issues begin to develop in this technology and it becomes important to use other technologies to overcome the limitations imposed by diffraction. Atomic force microscopy is the technique which allows the imaging of the most basic structure of molecules.
The beginning idea of atomic force microscopy is that rather than “looking” at an object by bouncing photons off of it, you “Feel” that object. In scanning tunneling microscopy, one of the most basic of atomic force microscopy you take a probe which narrows to a single molecule and have that probe ran across the surface of a conductive material while electricity is being sent through the probe. This allows a computer to create a three dimensional image of the surface of an object at the atomic level¹.
There are other forms that allow for similar effects and all of them measure not the reflection of light but the reactions of the atomic forces of the atoms as the probe is attracted and repulsed by the parts of each atom. This means that scientists using this can record the location of the positrons and electrons in these materials at resolutions which would be impossible in optical imaging².
With the advancement of technology the need to make smaller technology becomes a more pressing issue. This is not only because people want smaller cell phones but because of physical limitations of computer speed based on size. As it reaches the nanotechnology level the use of atomic force microscopy becomes an invaluable tool. It could potentially allow engineers to make machines small enough to pass through the walls of cells, create smart materials and computers so small that you can barely see them that are more powerful than the best computers now. If this technology does change the world as many believe it is possible then it will be the atomic force microscopy that allows you to image the most basic structure of molecules³.
It is hard to imagine in some ways that a needle can be used to examine objects at a smaller size than optics but atomic force microscopy allows scientists to actually measure the basic forces that hold molecules allowing for understanding of objects far smaller than could be possible with any other current technology and perhaps as small as anyone will ever be able to see.
1- http://chemwiki.ucdavis.edu/Analytical_Chemistry/Instrumental_Analysis/Microscopy/Atomic_Force_Microscopy#Modes_of_Operation
2- http://www.aadet.com/article/atomic_force_microscopy
3- http://iopscience.iop.org/0957-4484/15/10/012
