Photoelastic observation of stress distributions in laser cleaving of glass substrates

Photoelastic observations of thermal stress were conducted during the separation of glass substrates by thermal stress cleaving with a laser. A polariscope system was built in the laser cleaving system for observation during laser cleaving, and isochromatic and isoclinic fringe patterns were studied to analyze the thermal stress induced by laser irradiation. The proposed method allows for the visualization of stress asymmetry that decreases the process accuracy, and for the detection of crack stagnation which decreases the process reliability.