Talk:Fresnel diffraction

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[edit] fresnel nubmer and approximation

On the page about fresnel's number, it says that this equation is only accurate when its greater than or equal to 1. Is this correct? On the page about diffraction, it says that it describes the more general case of diffraction when compared to far-field diffraction. These are contradictory, and this page only says its used when the wave is "a small number of wavelengths away from the diffracting object". Is it an approximation or genralization? Fresheneesz 06:02, 20 March 2006 (UTC)

In fact, the Fresnel approximation should be good whenever . N_F can be smaller than 1, but doesn't have to like in the far-field approximation. --Ahmes 14:37, 3 July 2006 (UTC)