Femtosecond Laser Processing of Polymethyl Methacrylate with an Axicon

Focusing a laser beam with an axicon lens produces a Bessel beam and increases the longitudinal interaction length. This report describes structural modifications to be extended deep in polymethyl methacrylate (PMMA) using a femtosecond laser with an axicon. We investigated the dependence of the morphology of filamentary structural modifications on the distance between the tip of axicon and the sample surface. The region of filamentary modification was greater than 10 mm long. Focusing–refocusing modifications of filaments were produced.