Abstract
The stress-birefringence which is caused by imperfections in single crystals of synthetic rareearth garnets has been observed and analysed by means of polarizing microscopy using a BraceKöhler compensator and the Sénarmont's method using a He-Ne laser. The stress-birefringence associated with the inhomogeneities in the garnet crystal can be divided into three types according to the origins. One is associated with growth striations, another with facets and the other with dislocations and inclusions. In this study, the features of stress-birefringence of the three types are briefly described. It is demonstrated that measuring the value of the birefringence (Δn) and the vibration directions of polarized rays (X', Z') is important to characterize such defects. Besides the validity as the characterization method, such a photoelastic study is helpful to understand the environment during crystal growth.
