The wave nature of light has been widely demonstrated in a double-slit experiment, which has played a special role in physics teaching. When monochromatic light passes through the double-slit sheet, the diffraction and interference fringes can be observed in the far-field regime. The interference of light causes the beams passing through the two slits to interact with each other, but each slit still retains the diffraction characteristics of a single slit, so the result is a combination of diffraction and interference patterns.