Lasers are often used as light sources in different measuring systems. This course will present a new look at the operation of such systems from the viewpoint of speckle optics. The topics will include speckle statistics, speckle dynamics, basics of interference of two dynamic speckle patterns, relation between the Doppler effect and speckle dynamics, formation of speckled speckles, statistics of speckles with a small number of scatterers, fundamentals of multiple scattering of coherent light, and diffusing wave spectroscopy. The course emphasis is on understanding the principles of speckle metrology. It will concentrate on the problems of practical measurements, not on abstract theory. Many examples of applications of speckle in diagnostics and measurements will be included.