Sign of elongation
sign of elongation
(Science: microscopy) Referring to the elongation of a substance in relation to refractive indices. If it is elongated in the direction of the high refractive index, it is said to have a positive sign of elongation. If it is elongated in the direction of the low refractive index, it has a negative sign of elongation, not to be confused with the sign of double refraction (i.e., optic sign).