Limit of resolution of optical microscope

Optical Microscope uses system of lenses and visible light to sharply magnify small detailed samples which is projected directly to the eye.

In the 1870s, Ernst Abbe explained why the resolution of a microscope is limited. Since the microscope uses visible light and visible light has a set range of wavelengths. The microscope can't produce the image of an object that is smaller than the length of the light wave.

Limitations of Resolution


 * The diffraction limits the resolution to approximately 0.2mm.
 * It is difficult to differentiate the four lines drawn within a 250 micrometer. Below this line lies the realm which is invisible to human naked eye: 200-250 micrometer approximately.
 * The resolution of the light microscope cannot be small than the half of the wavelength of the visible light, which is 0.4-0.7 micrometer. When we can see green light (0.4 micron), the objects which are, at most, about 0.2 micron. Below this point, light microscope is not useful, as wavelength smaller than 400 micrometer is needed.

The waves that associate the electrons has smaller wavelength. Then we can use electrons using an electron microscope.