Thick modulated planar film-foam target fabricated by femtosecond laser micromachining

Dual layer Polystyrene(PS)-poly-4-methyl-1-pentene(PMP) foam with thickness of 1.5 mm, used in Rayleigh-Taylor hydrodynamic instability experiments, was accurately cut employing femtosecond laser irradiation with 800 nm central wavelength, 120 fs duration, 1 kHz repetition rate focused by microscopic objective(5×, NA=0.14). During the cutting, the manner of uniform step descending of laser focus and processing parameters with average incident power of 30 mW, cutting speed of 300 μm/s were adopted. Compared with the case of nanosecond laser cutting, detrimental distortion and delamination of the dual heterogeneous layer around the femtosecond laser irradiated zone were effectively avoided. Uniform cutting edge and smooth facet were also obtained, with maximal cutting thickness exceeding