This book is designed to highlight the basic principles of fiber optic imaging and sensing devices. The book provides the readers with a solid foundation in fiber optic imaging and sensing devices. The text begins with an introductory chapter that starts from Maxwell's equations and ends with the derivation of the basic optical fiber characteristic equations and solutions (i.e. fiber modes). Also covered within are reviews of the most common fiber optic interferometric devices which are the basis for many fiber optic imaging and sensing systems. The author discusses the basics of fiber optic imagers with an emphasis on fiber optic confocal microscope. Including chapters on fiber Bragg grating based sensor and various applications and fiber Sagnac loop based sensors. The book also provides useful forms of device characteristic equations.