Diffraction characteristics of laser transmission

The diffraction effect of the laser emission system is simulated using the format of 2D Fourier transform of the Fresnel diffraction integral formula. The method of fast Fourier transform(FFT) is used to calculate diffraction integral formula, and the condition under which the secondary phase factor meets the sampling theory is discussed. Different methods applied to calculating the diffractive field of different transmission distance are proposed. The transmission effect of intensity modulation for input laser is analyzed.