Microscopy to Nanoscopy

There is a human tendency to believe in what is actually seen by the eye. The universe, however, is made of objects all of which cannot be seen with the naked eye. Today, as we understand, the eye is a human instrument having a convex lens in it which possesses a limited resolving power.

- Dr. Dilip S. Joag

Resolving power is the ability of an instrument to recognise two closely lying objects as separate objects. When one tries to see small objects which are not easily resolved by the eye, a magnifying glass may be used. The human eye can clearly see small objects with size upto the order of fraction of a millimeter. To clearly see objects of sizes of the order of a few microns an optical microscope is used. It can resolve objects having size as small as a few microns and can magnify the objects several thousand times. But mere high magnification does not mean that one can see the object clearly. Clarity of the image depends upon the resolving power of the optical microscope. One common application of optical microscopy is to observe living cells such as RBCs, onion cells, microorganisms in water, microst