Effect of hole grating gradient on farfield

With the help of wave theory of light, the effect of hole grating gradient on farfield is analyzed by numerical calculation in this paper. The results show that the systemic error of measurement of intensity(power, beam quality, etc. ) of farfield is definite, and the more the gradient is ,the more the diffractive grade is, the bigger the effect. The smaller gradient and diffractive grade should be chosen while using hole grating to diagnose the beam power and quality.