Laser-based manufacturing of 2.5D bodies of Polylactide

Ultrashort laser pulses offer enormous potential for precise micro structuring, especially of transparent materials [1-2]. When focusing ultrashort laser pulses into the material, the intensity in the focus volume is sufficient to induce non-linear absorption processes, which lead to structural changes in the material volume [3]. In the following study, the localized structural changes were arranged in order to produce cut surfaces for the extraction of 2.5D bodies with potential applications for example in the production of micro implants. The investigations were carried out in polylactide, a bioresorbable polymer. For this purpose, a femtosecond laser source was used which emits pulses of 200 fs pulse length at a wavelength of 1030 nm. Microscope objectives with focal lengths in the range of 12.5 mm down to 2 mm were used, which resulted in focal radius of 1.2 mu m in minimum and hence extremely high intensities of about 10(15)W/cm(2) to excite nonlinear absorption effects. Process-influencing parameters such as pulse energy, pulse distance and frequency were varied to investigate their effect on the quality of the cut-out bodies. The feasibility of the technology could be demonstrated on the basis of simple bodies.