Levelling Laser and Optical Projection Lens

A levelling laser for generating a laser projection line on a surface is disclosed. The levelling laser includes an optical projection lens with a three-dimensional lens surface. The projection lens can be described in a three-dimensional coordinates system having three axes, X, Y and Z, arranged orthogonally to one another. The Z-axis coincides with the optical axis of the projection lens. The lens surface of the projection lens has a shape with a surface inclination angle rising monotonically along the X-axis. A corresponding projection lens is also disclosed.