The classical film stack (0.5LH0.5L)ⁿ induces half-wave holes due to its inhomogeneity of refractive index. In the design of film structures, the film possessing a homogeneous refractive index is usually assumed. When its optical thickness is half of the central wavelength, the film can be regarded as an absent layer. Unfortunately, in the practical fabrication, there exists some inhomogeneity in the refractive index of the film, which causes the optical thickness of the film inconsistent with theoretical design, and thus half-wave holes occur. Here the basic periodic structure of the film is optimized. The optical admittance of the optimized film structure at half wave is no longer affected by the refractive index inhomogeneity. On this basis, a harmonic beam splitting film is designed and fabricated that effectively eliminates the half-wave hole phenomena. The theoretical and experimental spectral curves are in a good agreement.