Version 2017-01-19 for GI use
5.
If Fresnel fringes appear in the holes of the carbon grid as lateral shadows,
instead of a well-centered rings, adjust the center with screw xx and yy
6.
Explanations-Theory
http://www.uiowa.edu/~cmrf/methodology/tem/tem_pg3.html
To optimize imaging in the TEM a beam alignment should be performed prior to use. A
tool for this alignment is a holey grid. A holey grid is a TEM grid support coated with a
thin plastic film and a stabilizing carbon layer. It is manufactured to contain small
round holes useful in alignment of the TEM. The holes in the grid create Fresnel fringes
when the electron beam diffracts around the edges as the electrons come together at
overfocus. The edge of the hole appears to have bands or fringes.