Design and computational analysis of continuous wave fiber laser cutting of flat and conformal ITO PET sheets

Metamaterials are engineered to exhibit properties that are not available in the nature. One of the prominent applications of the metamaterial is the use as RADAR absorbing material on military vehicles and vessels. There are different fabrication techniques available however, some become absolute when fabrication is needed to be conducted on conformal surfaces. Laser micromachining is an optimum choice to overcome this hurdle and can be versatile in nature. Different laser sources have different impact on the material for ablation. Indium tin Oxide Polyethylene terephthalate (PET) sheet was considered for the study for its high optical transparency and high flexibility. Five parameters were studied that include fluence, marking speed, line space, pulse width and working height to understand their impact on the material for development as effective metamaterial absorber. It was found that fluence energy as low as 0.25 J/cm², marking speed of 3000 mm/sec, line space of 0.05 mm which is equal to spot size, pulse width reduced to 1 ms and working height at focus (160 mm) were optimum for machining with minimum damage to PET substrate and minimum loss in optical transparency in our study.