Device and method for measuring deformation of a mechanical test specimen

A device as claimed in any one of the foregoing claims, characterized in that said interferometer (9) comprises a Michelson interferometer in turn comprising:

• a light source (29) for generating a light beam (F) traveling along a supply branch (9a);
• beam splitting means (30) receiving said light beam (F) generated by said light source (35), and generating a first (F2) and a second (F1) light beam;
• a measuring branch (9d) comprising said specimen (16), and for receiving and reflecting said first light beam (F2) on to said beam splitting means (30);
• a reference branch (9c) comprising reflecting means (39) for receiving and reflecting said second light beam (F1) on to said beam splitting means (30);
• and
• an acquisition branch (9b) comprising image acquisition means (44) for receiving said first light beam (F2) reflected by said specimen (16) and said second light beam (F1) reflected by said reflecting means (39).

A device as claimed in any one of the foregoing claims, characterized in that said light source (35) may be selected from the group comprising:

• a low-coherence source for white light interferometry measurements;
• a high-coherence source with a single nonadjustable frequency for ESPI measurements;
• and
• a high-coherence source with two non-adjustable frequencies or a single adjustable frequency for ESPI profilometry measurements.

A method for measuring the deformation of a mechanical test specimen, said specimen (16) being generally flat, and being defined by at least a substantially flat first face (16b);

• characterized by comprising the steps of:
• directing a first light beam (F2) onto said first face (16b) of said specimen (16) and acquiring (40) the reflected beam;
• producing interference between said reflected beam and a reference beam (F2) to obtain interference images;
• mechanically stressing the specimen (16) in a controlled manner by exerting a controlled concentrated force on a face of the specimen (16) deforming mainly the portion of the specimen (16) where the concentrated force is applied;
• and
• acquiring (44) and processing (27) said interference images to obtain information relative to the deformation of said specimen (16).