A method for controlling gas dynamic spraying includes



providing a particle jet by using an accelerating nozzle,
illuminating the particle jet with illuminating light pulses,
capturing images of the particle jet illuminated with the illuminating light pulses, and
determining one or more velocity values by analyzing the captured images, wherein the images are captured by using an imaging unit which includes imaging optics to form an optical image of an object plane on an image sensor by focusing light, wherein an optical axis of the imaging unit is inclined with respect to a central axis of the nozzle, and wherein the image sensor is inclined with respect to the optical axis such that the object plane is substantially parallel with a direction of movement of particles of the particle jet.