The field of coherent optics has stimulated much interest and indeed excitement over the past decade, and a number of engineering applications have been brought to light. The most significant of these are the subject of this senior- or graduate-level text, which was originally prepared—but is not limited to—electrical engineering students. It emphasizes the analogy between optical and electrical systems, both of which, for example, are capable of performing Fourier transform operations and signal filtering and processing. The book is designed for students without an intensive background in electromagnetic theory and classical optics. Its discussion of diffraction is based on scalar theory, and it approaches information processing and holography by means of the elementary point concept and linear system theory. This approach simplified the analysis so that solutions may be directly calculated, and it will appeal to engineering students because of their familiarity with the concepts of the impulse response of linear systems. After an opening presentation of the basic properties of linear systems and Fourier transformations, the book develops the theory of diffraction. The topics taken up include, among others, Fraunhofer and Fresnel diffraction, the reciprocity theorem, Huygens' principle, Kirchhoff's integral, the Fresnel zone plate, the Rayleigh criterion, and Abbe's sine condition. This part closes with a discussion of coherent theory and the mutual coherence function. The next part, on information processing, covers the Fourier transform properties of lenses and linear optical imaging systems, filtering, the basic properties of photographic film as a recording medium, film-grain noise and signal-to-noise ratio, the information channel capacity of photographic film, and optical resolving power and its relation to the uncertainty of information and physical realizability. The final part throws a clear light on the subject of holography. The presentation includes both linear and nonlinear holograms and takes up wavefront construction and reconstruction, magnifications, resolution limits and bandwidth requirements, finite-point analysis linear optimization techniques, syntheses of optimum nonlinear spatial filters, and applications. Among the latter are microscopic wavefront reconstruction, multiexposure holographic interferometry, time-average interferometry, and contour generation.