Diffraction

Huygens's Principle states that every point on a wavefront is a source of wavelets, which spread forward at the same speed.

The double-slit experiment, also called Young's experiment, shows that matter and energy can display both wave and particle characteristics.

Diffraction grating has periodic structure that splits and diffracts light into several beams travelling in different directions.

Single slit diffraction is the phenomenon that occurs when waves pass through a narrow gap and bend, forming an interference pattern.

The Rayleigh criterion determines the separation angle between two light sources which are distinguishable from each other.