This book deals with various aspects of optical imaging such as technologies and design, evaluation and calibration, and their scientific applications and results. It discusses the fundamental aspects of optical imaging, Fourier optics, and imaging physics with emphasis on image retrieval techniques and anatomy and diagnostics of optical imaging systems. In addition to ray optics, the book describes the technical details of several important instruments, such as spectroscopes, microscopes, telescopes, interferometers, and medical diagnosis-related instruments. Added further are the factors that affect the quality of the images, speckles and holography, and passive and active methods that permit a telescope to achieve diffraction-limited imaging from the ground. The book will be a valuable resource for astronomers and students involved in the design of modern instrumentation or those attempting to make use of data with instrumentation designed by others.