Besselbeams

Bessel beams are a unique class of optical beams that possess a non-diffracting propagation property, meaning they can maintain their shape and intensity over a considerable distance, unlike conventional Gaussian beams which spread out as they travel. This remarkable characteristic arises from their specific mathematical description, which involves a Bessel function. In essence, a Bessel beam is an approximation of a true, non-diffracting beam, as ideal Bessel beams would extend infinitely in both space and time.

The generation of Bessel beams typically involves a spatial light modulator or a special optical element called a Bessel beam generator, often realized by a conical lens (axicon). When a laser beam passes through an axicon, it is refracted in a conical manner, and the superposition of these conical wavefronts creates the Bessel beam. A key feature of Bessel beams is their "nondiffracting" nature, which is an approximation in practice due to the finite size of the beam and the limitations of the generation optics.

Due to their ability to maintain their focused spot size over a long propagation distance, Bessel beams have found applications in various fields. They are used in optical micromanipulation, where their stable structure allows for precise trapping and manipulation of microscopic particles. In microscopy, Bessel beams can enhance imaging resolution and reduce photodamage to biological samples by confining the illumination to a narrow focal region. Their non-diffracting property also makes them suitable for applications in laser material processing and in alignment systems where maintaining a defined beam profile is crucial.