wave optics

What happens when you send collimated light through a tiny hole?

Geometrical optics says we should get a small hole on the other end. But in reality we don’t. We get an airy disc pattern.  Described as
for holes

λ is wavelength

d is diameter


for slits

λ is wavelength

a is slit diameter

m is order number

The best way to observe these phenomena is by looking at what happens when we shine light though different shaped holes. As observed the diffraction pattern is caused not by the hole but the edges of the hole

Tiny Hole							Very Tiny hole

Square Grating					Large Square Grating

Hexagon Grating					Knife Edge

Some more Detailed Links




Pictures By Robert Balonek


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