You cannot see a virus under a optical microscope. It requires a Electron Microscope. That pretty darn small.
An
electron microscope is a
microscope that uses a beam of accelerated
electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light
photons, electron microscopes have a higher
resolving power than
light microscopes and can reveal the structure of smaller objects. A
scanning transmission electron microscope has achieved better than 50
pm resolution in
annular dark-field imaging mode
[1] and
magnifications of up to about 10,000,000× whereas most
light microscopes are limited by
diffraction to about 200
nm resolution and useful magnifications below 2000×.
Electron microscopes use shaped magnetic fields to form
electron optical lens systems that are analogous to the glass lenses of an optical light microscope.
Electron microscopes are used to investigate the
ultrastructure of a wide range of biological and inorganic specimens including
microorganisms,
cells, large
molecules,
biopsy samples,
metals, and
crystals. Industrially, electron microscopes are often used for quality control and
failure analysis. Modern electron microscopes produce electron
micrographs using specialized digital cameras and
frame grabbers to capture the images.