Home >> Atomic-resolution Holography Electron Microscope >> Overcoming the Aberration Barrier
Electron microscopes use electrons to make observations. Since the wavelength of electrons is much shorter than that of visible light, smaller objects can be observed. The extent of the ability to recognize small objects is measured in units of length and, in general, is referred to as resolution. Since the wavelength of electrons is less than 1/100 of an atom, 1 picometer (1 pm), it is assumed that resolution to this level can be attained. In practice, however, this is not yet possible: the highest resolution to date is approximately 50 pm.
Scientists have run into a wall in terms of improving the resolution of electron microscopes, a wall called "aberration," which is common to any lens.
There are two types of aberration: spherical aberration and chromatic aberration. Let’s consider spherical aberration here. In optical microscopes, the object being observed is magnified using a convex glass lens, while in electron microscopes, an electromagnetic lens equivalent to the convex lens is used. When using a convex lens, it is assumed that the light/electrons emitted from one point gather at a focal point, but this is not necessarily true. Since a part of a sphere is used for the lens, there is usually a difference in the refracted amount between the light passing through near the center of the lens and the light passing through places away from the center. This is spherical aberration. As a result, the image is blurred by the lens.
Optical Microscope
Electron Microscope
