A surgical instrument positioning system, comprising: at least one support; a cross member having at least one curved end portion, the at least one curved end portion being held by the at least one support such that the cross member is rotatable about an axis extending through a center of curvature of the at least one curved end portion of the cross member; and at least one surgical instrument holder suspended from the cross member.A laser alignment system for an image intensifier, comprising: at least one laser source which emits planar laser beams in first and second intersecting planes.