1. A system for non-destructive testing of an object, comprising: (a) means for holding the object, (b) means for vibrating the object, the vibrating means being connected to the holding means, (c) means for directing a beam of coherent light onto a predetermined point on the object, so as to form a reflection pattern, (d) means for detecting the reflection pattern obtained from the object, (e) control means, the control means being adapted to energize and de-energize the vibrating means, and to control the beam directing means, wherein successive points on the object can be scanned by the beam, the control means being programmed to energize and de-energize the vibrating means while the beam is directed towards each point on the object, and (f) display means for indicating, for each point on the object, the difference between the reflection pattern when the object is vibrating and when the object is stationary.