Mapping surface stress of automotive glass by non-contact polarimetric scans

Polarimetric methods using the properties of photoelasticity and polarisation optics allow the evaluation of stress patterns in transparent materials. Those are well established for transmission geometries measuring the integrated stress through the whole volume along the light path. On the contrary, surface sensitive measurements are challenging to realise, thus, rarely found and much less precise. However, due to the rising requirements concerning glass quality a surface stress measurement method, potentially suitable for inline processes, is needed. We are developing a non-contact and spatially resolved polarimetric measurement technique to evaluate the surface stress of single-pane and laminated safety glass, which is beyond the current industrial standard methods.