The refractive indices at 12 wave lengths in the visible region were measured with the minimum deviation method , showing that kabo is a negative uniaxial optical crystal with moderate birefringence . the measurement of nonlinear optical coefficient dn = 0 . 45pm / v 用最小偏離法測試了可見光區十二個波段處的晶體折射率,結果表明kabo晶體屬負單軸晶,具有適中的雙折射率。晶體的非線性光學性質測試顯示,該晶體非線性光學系數為d _ ( 11 ) = 0 . 45pm / v ,可實現相位匹配。