Study of femtosecond laser beam focusing in a direct-write system

En col·laboració amb la Universitat Autònoma de Barcelona (UAB) i la Universitat de Barcelona (UB).Direct-write techniques appear as a versatile option in rapid-prototyping applications because they can directly transfer a custom pattern from a digital file. Lasers are a distinguished tool which allow to perform non-contact direct-write techniques with the ability to add, remove and modify different types of materials. Moreover, they have a high focusing power and offer high spatial resolution when a femtosecond laser is used due to the reduction of thermal effects. Additive and subtractive techniques can be performed in one laser-based direct-write system with minimum variations in the setup. In all cases, properties of the laser beam, such as the beam width or the morphology of the intensity distribution have an effect on the results of the laser processing. The aim of this work is the study of the laser propagation in a specific laser-based direct-write setup. The beam intensity distribution effects are measured at different positions and compared with simulations. The influence of the main parameters, pupil displacement and objective tilt, on the morphological properties of the intensity distribution is analysed. Well defined spots with good reproducibility are obtained. In addition, at comparing the simulation with the experiments, the origin of some morphological properties are reported and they can be used to optimize the setup

Laser microprinting of liquid suspensions

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Any: 2015, Tutor: Pere SerraLaser-induced forward transfer (LIFT) is a non-contact direct-write technique with a high spatial resolution and able to print a wide range of liquids in air and at room temperature. The versatility of LIFT has made it a promising alternative to lithography-based processes for the rapid fabrication of biomolecule microarrays. The aim of this work is the study of LIFT using femtosecond laser pulses and a solution suitable to act as a solvent for biomolecules. The influence of the main process parameter, laser pulse energy, on the morphological properties of the transferred droplets is analyzed. Circular and uniform droplets are obtained with good reproducibility. In addition, we observe a relationship between energy and droplet radius never identified before: a linear dependence of the radius to the fifth power with laser pulse energy