Optical device and method for inspecting structured objects

A method for inspecting structured objects, comprising:

• producing, on a camera, an image of the object according to a field of view, implementing a distal lens arranged on the side of the object;
• producing a lighting beam with visible wavelengths using lighting means, wherein the lighting beam is arranged in such a way as to illuminate the object through the distal lens;
• producing measurements by interferences between retroreflections of a measurement beam and at least one optical reference, from a low-coherence infrared interferometer emitting this measurement beam with a plurality of infrared wavelengths, wherein the low-coherence interferometer comprises a decoding interferometer having an arm with a fixed reference and an arm with a time delay line;
• providing an optical coupling for inserting the measurement beam issued form an optical fiber of the interferometer and a collimator into the distal lens in such a way that it passes through the distal lens and that it intercepts said object according to a measurement region substantially included in the field of view of the distal lens;
• generating the optical reference by reflecting part of the measurement beam in the optical fiber at the collimator;
• and
• adjusting the difference in optical length between said arms and the maximum stroke of the delay line in the low-coherence infrared interferometer in such a way that only the measurement beam retroreflections that occur in a measurement range encompassing interfaces of the object produce usable interferences with the optical reference and parasitic reflections in the distal lens do not contribute significantly to said interferences.