Antisymmetric Distribution of Permanent Refractive Index Change in β-BaB2O4 Crystal Under Exposure of Femtosecond Pulses.A.G. Okhrimchuk, S.G. Grechin, A.E. Kokh and V. MezentsevMATEC Web of Conferences, 8 (2013) 02003DOI: https://doi.org/10.1051/matecconf/20130802003