a-BBO, high temperature phase of BaB2O4, is an excellent birefringent crystal 1. Basic propertiesCrystal structureHexagonal ... 6/K, //C-axis, 36.3´10-6/KThermal coefficients of refractionDn0/DT=-8´10-6/ºC; Dne/DT=-2´10 ... , 1.3ns pulse)15GW/cm2(1064nm, 0.1ns pulse)Specifications of a-BBODimension toleranceW ± 0.2 mmWavefront distortion:l/8 @ 633 ... 5 arc minutesAngle tolerance:Dq < ±0.5°, Df < ± 0.5° a-BBO