Image Modes in TEM - Bright Field Images

TEM | Image Formation | Dark Field Images | Lattice Images (HRTEM)

In the bright field (BF) mode of the TEM, an aperture is placed in the back focal plane of the objective lens which allows only the direct beam to pass. In this case, the image results from a weakening of the direct beam by its interaction with the sample. Therefore, mass-thickness and diffraction contrast contribute to image formation: thick areas, areas in which heavy atoms are enriched, and crystalline areas appear with dark contrast. It should be mentioned that the interpretation of images is often impeded by the simultaneous occurence of the contrast-forming phenomena.