4. Determining the normalized radius of any stable beam

Because of the imprecision of its lateral boundary, it is difficult to practically measure the diameter of a beam at any point of its propagation. A simple indentation in a plastic block, or even better, a beam analyzer, reveals not only this imprecision but also, very often, the non-circularity of the cross-section.

• The ISO 11146 standard extends to any distribution the notion of $\omega$ radius that naturally arises for a Gaussian beam, expressed in paragraph 2