Scientific Background
It has long been known that the best achievable spatial resolution of an optical microscope, that is the smallest feature it can observe, is of the order of the wavelength of the light λ, which is about 550 nm for green light. One route to improve this resolution is to use particles with smaller λ, such as high-energy electrons. Practical limitations set a convenient electron energy to 100–300 keV that corresponds to λ = 3.7–2.0 pm. Unfortunately, the resolution of electron microscopes is limited not by the electron wavelength, but by intrinsic imperfections of electron lenses. These are referred to as spherical and chromatic aberrations because of their similarity to aberrations in optical lenses. Those aberrations are reduced by installing in a microscope a set of specially designed auxiliary "lenses" which are called aberration correctors.
Read more about this topic: Transmission Electron Aberration-Corrected Microscope
Famous quotes containing the words scientific and/or background:
“We have our little theory on all human and divine things. Poetry, the workings of genius itself, which, in all times, with one or another meaning, has been called Inspiration, and held to be mysterious and inscrutable, is no longer without its scientific exposition. The building of the lofty rhyme is like any other masonry or bricklaying: we have theories of its rise, height, decline and fall—which latter, it would seem, is now near, among all people.”
—Thomas Carlyle (1795–1881)
“I had many problems in my conduct of the office being contrasted with President Kennedy’s conduct in the office, with my manner of dealing with things and his manner, with my accent and his accent, with my background and his background. He was a great public hero, and anything I did that someone didn’t approve of, they would always feel that President Kennedy wouldn’t have done that.”
—Lyndon Baines Johnson (1908–1973)