This book describes Microelectromechanical systems (MEMS) technology and demonstrates how MEMS allow miniaturization, parallel fabrication, and efficient packaging of optics, as well as integration of optics and electronics. The book shows how the characteristics of MEMS enable practical implementations of a variety of applications, including projection displays, fiber switches, interferometers, and spectrometers. The authors conclude with an up-to-date discussion of the need for the combination of MEMS and Photonic crystals.