Since the advent of the laser, coherent optics has developed at an ever-increasing pace. There is no doubt about the reason. Coherent light, with its properties so different from the light we are surrounded by, lends itself to numerous applications in science, technology, and life. The bandwidth of coherent optics reaches from holography and interferometry, with its gravitational wave detectors, to the CD player for music, movies, and computers; from the laser scalpel, which allows surgical cutting in the interior of the eye without destruction of the layers penetrated in front of it, to optical information and data processing with its great impact on society. According to its importance, the foundations of coherent optics should be conveyed to students of natural sciences as early as possible to better prepare them for their future careers as physicists or engineers. The present book tr.