Electron holography, a two-step imaging method taking advantage of light and electrons, has been employed for fundamental experiments in physics as well as for high-precision measurements in microscopy. It continues to be advanced in its applications though the speed of the development is not high but steady together with technical improvements of both the coherent electron beam and the reconstruction system. Progress has been made since the publication of the first edition of this book in 1993, and this second edi­ tion with new results integrated is herewith made available. I hope that the present monograph will help develop this interesting field of electron interference further. Hatoyama Akira Tonomura December 1998 v Preface to the First Edition Electron holography has recently paved a new way for observing and meas­ uring microscopic objects and fields that were previously inaccessible em­ ploying other techniques. Full use is made of the extremely short wave­ length of electrons, enabling electron holography to have a great impact on fields ranging from basic science to industrial applications. This book will provide an overview of the present state of electron holography for scien­ tists and engineers entering the field. The principles, techniques and applications which have already been developed, as well as those which are ex­ pected to arise in the near future, will be discussed.