Diffraction by a rectangular aperature
When light passes through a small aperature, each point within the aperature behaves like a point source
of light waves, resulting in diffraction of the light. If the light then falls on a screen beyond
the aperature, it forms a diffraction pattern of bright patches separated by dark diffraction
minima. The applet below allows you to adjust the width a, height b of the aperature
as well as the wavelength of the light. Watch what happens to the pattern when the width is made smaller.
A button will superimpose coordinate axes on the pattern so that you can verify the mathematical formulas
for the locations of diffraction minima.
The axes represent the deflection angles, in units of 1/10,000 radians.