Magnification and resolution

These images compare the appearance of mitochondria at the maximum magnification of the light microscope (1000x) (above) with that seen by the electron microscopy at 45,000x (below). In the electron micrograph, the mitochondria are larger, but importantly, because of the higher resolving power of the electron microscope, they are visible as individual structures (even within clumps) and their internal structure is revealed.

These images compare the appearance of mitochondria at the maximum magnification of the light microscope (1000x) (above) with that seen by the electron microscopy at 45,000x (below). In the electron micrograph, the mitochondria are larger, but importantly, because of the higher resolving power of the electron microscope, they are visible as individual structures (even within clumps) and their internal structure is revealed.

Resolution, a numeric quantification, is defined as the minimum distance at which two objects must be separated in order to be seen as individual structures. This property is fundamentally based on the wavelength of the illumination, with shorter wavelengths providing greater resolution.

Longer wavelength illumination, e.g., white light, is unable to pass between these two objects and thus they appear to be overlapping in the final image. For light microscopy, objects must be separated by more than 200 nm in order to be distinguished as separate structures.

Shorter wavelength illumination, e.g., an electron beam, is able to pass between these two objects and thus they appear as distinct structures in the final image. Resolving power is a major advantage of electron microscopy where objects can be as close as 1.0 nanometer and still can be distinguished as separate structures. The wavelength of an electron can be up to 100,000 times shorter than that of visible light.