A method and apparatus for inspecting an object. The apparatus comprises a vibration generator and an acousto-optical sensor. The vibration generator is positioned relative to a surface of an object. The vibration generator excites the object at a location on the object such that the portion of the object vibrates. The acousto-optical sensor is coupled to the surface of the portion of the object. The acousto-optical sensor detects a vibratory response generated by the portion of the object in response to excitation of the portion of the object and generates an image of the portion of the object based on the vibratory response.