Principles of Electron Optic: Volume Three: Wave Optics, discusses this essential topic in microscopy to help readers understand the propagation of electrons from the source to the specimen, and through the latter (and from it) to the image plane of the instrument. In addition, it also explains interference phenomena, notably holography, and informal coherence theory. This third volume accompanies volumes one and two that cover new content on holography and interference, improved and new modes of image formation, aberration corrected imaging, simulation, and measurement, 3D-reconstruction, and more. The study of such beams forms the subject of electron optics, which divides naturally into geometrical optics where effects due to wavelength are neglected, with wave optics considered.