A uniqueness theorem for a surface with principal curvatures connected by the relation $(1-k_1d)(1-k_2d)=-1$

The next theorem is proved: let $F$ be an oriented complete analytic surface in three-dimensional Euclidean space with principal curvatures satisfying the following relation: $(1-k_1d)(1-k_2d)=-1$ то $F$. Then $F$ is a direct circular cylinder.