Piezooptic Properties of beta-BaB2O4 and Li2B4O7 Crystals

Photoelastic coefficients of beta-BaB2O4 and Li2B4O7 crystals are calculated on the basis of piezooptic measurements performed with interferometric technique and the elastic compliance and stiffness data. Using the experimental results, the acoustooptic (AO) figure of merit (FM) has been estimated for the possible geometries of AO interaction. It is shown that the AO FM for the ABO and LTB crystals reach respectively the values M2=243.4*10-15s3/kg and M2=2.57*10-15s3/kg, if the interaction with the slowest ultrasonic waves (v=933.5m/s and v=3173m/s) is concerned. The directions of propagation and polarization of those acoustic waves are obtained on the basis of construction of indicative surfaces of the acoustic wave velocities.