transmission electron microscopy bright-field transmission electron microscopy 2009-09-29T06:15:27Z bright field TEM bright field transmission electron microscopy bright-field TEM CHMO:0002470 https://orcid.org/0000-0001-5985-7429 BF-TEM Microscopy where an electron-transparent specimen is bombarded with a finely focused (<10 nm diameter) electron beam with an acceleration voltage 50–150 kV. under vacuum. The beam of electrons passes directly through an aperture before reaching the specimen. The image results from a weakening of the direct beam by its interaction with the sample.