Self-healing of Bessel beams

The electric field of ideal Bessel beams is proportional to the zeroth order Bessel function and their intensity profile is unaltered by propagation in free space. Furthermore, these beams can reconstruct themselves after being disturbed by an obstruction, which is referred to as “self-healing-effect”. In the laboratory we can generate approximations of ideal Bessel beams, which have approximately the same properties along a finite range. Due to the self-healing effect, the beams are advantageous for micro drilling of (transparent) materials, or for optical tweezing, for example. For investigating this self-healing effect in further detail, a set-up was built, which visualizes the reconstruction of the beam. It allows capturing images of the beam along variable distances behind an obstruction and in this way, the whole self-healing process can be reproduced. The measurements are in good agreement with numerical simulations and the results allow a better understanding and assessment of the self-healing properties of Bessel-beams in practical applications.