This article describes an experimental apparatus that forms the basis for operation of Laser Velocimeters. The setup is used to measure the velocity of a well-known physical system. The use of this experimental apparatus allows the students to understand the effects of interference, diffraction and scattering of light, by means of an optical measurement technique with several applications in particles velocities measurements. A simple pendulum is the physical system chosen to be analyzed, once its velocity can be easily calculated and the theoretical predictions compared with the experimental values.
