Scanning electron microscope, resolving power

The classical polarizing light microscope as developed 150 years ago is still the most versatile, least expensive analytical instrument in the hands of an experienced microscopist. Its limitations in terms of resolving power, depth of field, and contrast have been reduced in the last decade, in which we have witnessed a revolution in its evolution. Video microscopy has increased contrast electronically, and thereby revealed structures never before seen. With computer enhancement, unheard of resolutions are possible. There are daily developments in the X-ray, holographic, acoustic, confocal laser scanning, and scanning tunneling micro-... 

Nanotechnology. Nanotechnology is an example of a scientific discipline whose very existence simply would not be possible without the use of extremely powerful microscopes. This emerging field takes advantage of the special ways in which molecules behave at the nanoscale to create nanoscale machinery such as tiny sensors that can detect and tally the number of specific types of molecules in a sample of chemicals or nanoparticles that systematically seek out and destroy cancerous cells within a patient s body. Op>-tical microscopes do not have the magnifying power necessary to clearly resolve objects at the nanoscale (about 1-100 nanometers, or about one-thousandth the width of a strand of human hair), so electron microscopes and scanning probe microscopes serve as the foundational tools of nanoscientists. 

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