The anomalous beaming effect of the periodic metallic corrugations functioning as a special case of k_SP=2π/Λ is discussed and verified by means of both theoretical calculation and experimental probing. A metalens is designed on the basis of the special case. Unlike the conventional beaming of convergence or divergence, the metalens can realize beam collimating, which is useful for practical applications. As a typical application example of the metalens, we integrate the metalens together with a vertical cavity surface emission laser (VCSEL) on the top surface of the aperture area. Our experimental results demonstrate that the integrated metalens is capable of suppressing the divergence angle of the VCSEL for collimation use.