Dark Field Apertures, ID 1600µm, OD 1900µm, Large Center - Round Aperture, Nickel, Pack
Dispersed particulate material can be studied in thin cross section best with Dark Field Apertures. Structures in certain amorphous materials can also be imaged because the axial path of the electron beam is blocked in the condenser and the scattered electrons cause symmetrical indirect illumination. Perhaps some of the most interesting work of all is that which is done on polymer single crystals.
Only electrons scattered by the sample are actually transmitted. Note that the electrons beam does not have to be tilted. All other electrons are scattered out of the main beam. Disk is 3 mm in diameter by 0.066 mm thick. Select small or large aperture pattern, in copper or nickel.
Large Center - Round Aperture
Inner diameter 1600µm, outer diameter 1900 µm.
Nickel, 5 pk