313964d8_Microscopy__Determinative_value
[Optical property] Birefringence [Measurement] Numerical difference between two principal refractive indices. By subtracting larger refractive index from smaller or by measurement of retardation with a compensator and measurement of thickness. [Determinative value] 
Identification of crystalline and semicrystalline materials. Comparison of certain artificial fibers.
Microscopy
Determinative value