Dauphiné twin observation in quartz using piezo or electro-optic effects

Abstract

The influence of twinning in quartz on the piezooptic and the electrooptic tensors is examined from the point of view of symmetry. Since some tensor coefflcients change their sign with twinning one can make observations of twins using thèse effects. Several experimental dispositions using uniaxial stress or an electric field are discussed and experimental results are presented for Dauphiné twins, which are not visible by ordinary optical methods