Microscopic three-dimensional inner stress measurement on laser induced damage

Area of Science:

• Optical Engineering
• Materials Science
• Non-Destructive Testing

Background:

• Optical components can develop residual stress after laser-induced damage and repair.
• Accurate characterization of this stress is crucial for component integrity and performance.

Purpose of the Study:

• To propose and validate a novel three-dimensional (3-D) residual stress detection technique.
• To evaluate residual stress in optical components at laser-induced damage sites.

Main Methods:

• A cross-orthogonal reflective photo-elastic setup was employed.
• The damaged component volume was numerically sliced into multilayers.
• Reflected light intensity from each layer was recorded and analyzed using photo-elasticity theory.

Main Results:

• The technique successfully obtained complete 3-D information of residual shearing stress.
• Experimental validation demonstrated the capability to measure 3-D residual stress.
• An axial resolution of 10 µm along the light path was achieved.

Conclusions:

• The proposed 3-D photo-elastic technique is effective for detecting and evaluating residual stress in repaired optical components.
• This method offers precise 3-D stress mapping around damage sites.
• The technique provides high axial resolution for detailed analysis.