Wave Optics - Consistent Image Formation

Description:

Image that has a constant intensity is known as consistent image.

Consistent images are formed by the superposition of light waves, when two waves have either constructive or destructive superposition a consistent image is formed.

When there is constructive superposition between light waves (i.e. crest over crest), the intensity of the image is maximum and it stays maximum throughout i.e. constant intensity, hence forming consistently bright image.

When there is destructive superposition between light waves (i.e. crest over trough), the intensity of the image is zero and it stays zero throughout i.e. constant intensity as both the waves cancel out each other, hence forming consistently dark image.

When the two light waves do not have a constructive nor destructive superpositions, instead the two waves are not synchronised, there is a formation of inconsistent image with the average intensity of both the waves.

Consistent image formation requires coherent waves; as coherent waves provide consistent brightness.