Wave Optics - Limiting Case of Ray Optics

Description:

Light follows both the ray optics as well as the wave optics, so there is an ambiguity that which method should be used to study the image formation. This problem is solved using Fresnel’s distance.

Fresnel’s Distance

Fresnel’s distance is that distance upto which image formation is according to the ray optics and after Fresnel’s distance wave optics can be used.

Z_F = a²/λ

Fresnel’s distance for human eye is Z_F = 1.67 meters and the diameter of eye is only 2.5cm which is in the range of Fresnel’s distance, therefore we use ray optics for all the experiments.