Patent ID: 7978344

Claim:
System for surface inspection arranged to detect relative displacement and/or vibration characteristics of a plurality of points of a plurality of elements ( 51 ) forming part of a mechanical structure ( 5 ), said system comprising: a light source ( 1 ) arranged to generate at least one light beam ( 11 ); a position sensitive detector ( 2 ) arranged to receive the light beam when reflected off the mechanical structure ( 5 ) and to produce at least one output signal in response to receipt of said light beam; an electronic control system ( 3 ); scan means ( 4 ) for relative displacement of said light beam with respect to the mechanical structure ( 5 ) so as to scan said mechanical structure with the light beam, following instructions from the electronic control system ( 3 ); wherein said electronic control system ( 3 ) is arranged to control the scan means ( 4 ) so as to displace the light beam along the mechanical structure along a first trajectory (A), so as to detect a plurality of subsequent reference positions (C) along said first trajectory (A), wherein said electronic control system ( 3 ) is operatively associated with said position sensitive detector ( 2 ) so as to determine said reference positions (C) as a result of an analysis of at least one output signal from said position sensitive detector ( 2 ); wherein said electronic control system ( 3 ) is further arranged to control the scan means ( 4 ) so as to displace the light beam along the mechanical structure along a plurality of second trajectories (B), each of said second trajectories (B) being associated with one of said reference positions (C); said electronic control system further being arranged to obtain, during displacement of the light beam along each of said second trajectories (B), a plurality of position signal outputs from said position sensitive detector ( 2 ).