Each chapter has been revisited, obsolete material deleted and new developments included at various places so that the reader gets the best from the new edition. The new topics which have been included as separate chapters are: Scanning Electron Microscope and Scanning Probe Microscope (Scanning Tunneling Microscope & Atomic Force Microscope). Particle size analyzers play an important role in research and development and for quality control in many industries such as pharmaceuticals, ceramics, cement, paints and emulsions etc. Realizing the need of the users in these areas, a new chapter on Particle Size Analyzers and Counters has been included.