Smartphone hologram

The diffraction is described as the interference of waves according the Huygens Fresnel principle. These characteristic behaviors are exhibited when a wave encounters an obstacle or a slit that is comparable in size to its wavelength. In this case laser light bends when it passes through a diffraction grid (series of slits) and creating diffraction pattern on the screen.

While diffraction occurs whenever propagating waves encounter an obstacle or a slit, its effects are generally most pronounced for waves whose wavelength is roughly comparable to the dimensions of the diffracting object or slit. If the obstructing object provides multiple, closely spaced openings, a complex pattern of varying intensity can result.