Determination of the optical axis in $Z$-cut uniaxial crystals by a polarization-based method

A polarization method is proposed for determination of the orientation of the optical axis in a $Z$-cut uniaxial crystal. The applicability of the method for controlling the deflection angles of the optical axis from the normal to the crystal surface $\sim$0.01$^\circ$ was shown using the example of lithium niobate crystal with a thickness of 514 $\mu$m. Peculiarities of the practical implementation of this method and approaches for increasing its accuracy and throughput are considered.