It is crucial that any spherical aberration are removed by way of pinhole. The laser spot is passed through a pinhole, which acts to expand the beam. This expansion creates a patter known as an Airy pattern[ http://en.wikipedia.org/wiki/Airy_disk].
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It is crucial that any spherical aberration are removed by way of pinhole. The laser spot is passed through a pinhole, which acts to expand the beam. This expansion creates a patter known as an [http://en.wikipedia.org/wiki/Airy_disk Airy pattern].
* [[Huygens Principle for a Planar Source|Determining the angle of the diffraction minimum for a circular aperture]]
* [[Huygens Principle for a Planar Source|Determining the angle of the diffraction minimum for a circular aperture]]