A concave-convex Fresnel-lens for a lighting unit of a vehicle is provided. The concave-convex Fresnel-lens includes a convex output surface and a concave input surface. The convex output surface includes a Fresnel structure. The concave input surface has a first radius of curvature and the convex output surface has a second radius of curvature. The concave input surface is configured to be oriented towards a light source of the lighting unit.