Non-destructive quantification of internal stress in polymer materials by polarisation sensitive optical coherence tomography

Polarisation sensitive optical coherence tomography (PS-OCT) is an interferometric technique to determine and map the internal birefringence properties of translucent and turbid samples. Because of its non-destructive character, PS-OCT is an ideal method for material characterisation and testing. When birefringence patterns induced by mechanical strain are analysed, information about the stress within a material can be obtained. In this work, we investigate the stress in polymer samples using PS-OCT. From strain experiments under well defined loading conditions, we determine the stress optical coefficients for different materials by evaluation of the birefringence patterns. Applied to strained samples fabricated from these materials, the stress calibration allows a correlation of the birefringence with quantitative stress values within the materials.