Patterns of light observed from an observation plane perpendicular to the light source where the black and white represent different arrival times of the light at the observation plane.
	Patterns of light observed from an observation plane perpendicular to two light sources where the the vertical bars represent the area where the arrival times of the two light sources are always out of phase.
	Patterns of light observed from an observation plane perpendicular to the light source where the black and white represent different arrival times of the light at the observation plane. In this example the light in question has a noticeably longer wavelength.

Illustration of light as a ray | Illustrating Huygen's Principle | Diffraction | The actions and effects of lenses | Holography | Eyes | Simple optical systems