Korolev A.N., Lukin, A.Ya., Andreeva T.A., Bochman E.D., Venediktov V.Y., Gordeev S.V., Kosmina M.A., Schur V.l.
Estimation of metrological characteristics of a high- precision digital autocollimator using an angle encoder. J. Opt. Technol. 85(7), 406-409 (2018)