This International Standard describes the stress optical method for determining the birefringence in glass, especially in raw optical glass in bulk and preshaped forms. This method is also used in photo-elasticity. NOTES 1 The calculation of the elastomechanical stress from the birefringence is not the subject of this International Standard. 2 The indication on the drawings of birefringence is specified in ISO 10110-2 (see reference [2] in annex A). This test method is applicable for simple geometrical shapes of glass (see clause 5).