| 摘要 |
<p>Commercially available High Resolution Transmission Electron Microscopes (HR-TEM) and Scanning Transmission Electron Microscopes (HR-STEM) are nowadays equipped with correctors for correcting the axial spherical aberration C S of the so-named objective lens. Inevitably other aberrations become the limiting aberration. For the hexapole type correctors, also known as Rose correctors, or variants thereof, six-fold axial astigmatism, also known as A5, and sixth-order three lobe aberration, also known as D6, introduced by the corrector, are known to become the limiting aberration.
The invention shows that by adding a weak hexapole (126) in the cross-over between the hexapoles (110,112), a Rose like corrector or a Crewe like corrector free of A5 or D6 can be made, or, by adding both the weak hexapole (126) and a dodecapole (128), a corrector that is free of both A5 and D6.</p> |
