The physics of the high-resolution scanning microscope

The high-resolution scanning transmission electron microscope has significantly different characteristics from the conventional electron microscope. The process of producing images is in itself quite different but most significantly it is a quantitative instrument which is capable of providing numerical data on the properties of thin specimens. The author discusses the physics involved in the design and operation of the instrument. He has made little attempt to give details in particular designs because such details already appear in the literature. Instead emphasis is placed on the capabilities and limitations of the instrument and give some ideas of the direction of future developments.