Embodiments of the invention relate to electron microscopy. Example embodiments relate to an apparatus including a first electron beam source, a second electron beam source, and a receiving unit. The first electron beam source is configured to provide a first low-voltage electron beam to a surface of a sample. The second electron beam source is configured to provide a second low-voltage electron beam to pass through the sample. The receiving unit is configured to analyze the first low-voltage electron beam, or the second low-voltage electron beam, or both the first and the second electron beam to obtain information about the sample.