Simulation platform for grating diffraction experiment

We had established a simulation platform for grating diffraction experiment using visual basic. Wavelength of incident light, grating constant and the number of total slit determined the picture of grating diffraction experiment on the screen. The type of experimental picture was decided by the number of total slit. When the number of total slit equaled to one, it was single slit diffraction, there was a light and biggest band on the center of picture. When the number of total slit equaled to two, it was double silt interference, distance between every near two band was equal. While the number of total slit was greater than two, it was grating diffraction experiment. The picture from the simulation platform had well agreement with that form half wave zone method.