Martínez-Herrero, RosarioMaluenda Niubó, DavidJuvells Prades, IgnacioCarnicer González, Arturo2018-09-182018-09-182018-02-082045-2322https://hdl.handle.net/2445/124669We introduce a new method for producing optical needles with tunable length and almost constant irradiance based on the evaluation of the on-axis power content of the light distribution at the focal area. According to theoretical considerations, we propose an adaptive modulating continuous function that presents a large derivative and a zero value jump at the entrance pupil of the focusing system. This distribution is displayed on liquid crystal devices using holographic techniques. In this way, a polarized input beam is shaped and subsequently focused using a high numerical aperture (NA) objective lens. As a result, needles with variable length and nearly constant irradiance are produced using conventional optics components. This procedure is experimentally demonstrated obtaining a 53λ-long and 0.8λ-wide needle.10 p.application/pdfengcc-by (c) Martínez-Herrero, Rosario et al., 2018http://creativecommons.org/licenses/by/3.0/esPolarització (Llum)DifraccióFeixos de làserPolarization (Light)DiffractionLaser beamsinfo:eu-repo/semantics/article6818622018-09-18info:eu-repo/semantics/openAccess29422653