7.4.1.2. Generation of a Bessel beam with a lens and an annular slit.
By positioning an aperture around the disk a non-difracting Bessel beam is generated over a distance given by the ‘overlap area’. From geometric optics this distance can be estimated by:
\(z_{max}=\frac{Df}{a}\), where \(D\) and \(f\) are the diameter and focallength of the lens respectively.
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