Venn Diagram from Scientific Research

Examples of imaging a specimen (white circle) with different TEM beam set-ups: top, imaging with a round beam; middle, FFI with a round beam; bottom, FFI with a square beam. The areas on the specimen illuminated by the electron beam are shown in green circles (round beam) or green squares (square beam); in non-FFI TEM set-ups the beam must be spread out so the fringes do not fall on the sensor.

DOI