The graphene paper microsieves can be applied in the filtration of biological fluids or separation of solid particles from exploitation fluids. To produce graphene paper microsieves for specific applications, good control over fabrication should be achieved. In this study, a laser ablation method using a picosecond laser was applied to fabricate graphene paper microsieves. Holes in the microsieves were drilled using pulsed laser radiation with a pulse energy from 5 to 100 µJ, a duration of 60 ps, a wavelength of 355 nm, and a repetition rate of 1 kHz. The impact method was applied using 10 to 100 pulses to drill one hole. To produce holes of a proper diameter which could separate biological particles of a certain size (≥10 µm), optimum parameters of graphene paper laser ablation were defined using the MATLAB software taking into account laser pulse energy, repetition rate, and a desired hole diameter. A series of structural tests were carried out to determine the quality of an edge and a hole shape. Experimental results and Laguerre–Gauss calculations in MATLAB were then compared to perform the analysis of the distribution of diffraction fringes. Optimum experimental parameters were determined for which good susceptibility of the graphene paper to laser processing was observed.

An influence of some physical phenomena disturbing correct interpretation of LIBS spectra is described in the paper. The following phenomena were investigated: a way of laser beam focusing (power density), laser spark in air, spectral line broadening, apparatus efficiency and resolution, and an influence of those factors on LIBS spectra as well. They are particularly important for quantitative LIBS measurements. The presented measurement results clearly show that the correct elemental identification plays a significant role in artworks dating [5].

This paper presents the results of numerical calculations concerning the propagation and focusing of radiation in laser materialprocessing systems. The calculations concerned the assessment of the influence of diffraction on the energy density distributionin the beam focus zone. The calculations used simplified Maxwell equations, i.e., a parabolic equation describing radiation propagationusing a series of Laguerre-Gaussian functions. In the presented research and calculations, a pulsed laser beam with a maximum emissionenergy of 300 μJ, a diameter of 5.9 mm, a single pulse duration of 70 ps, and a wavelength of 355 nm was used. The beam was focused onthe sample using a telecentric lens with a focal length of f = 100 mm. The calculations were performed for a top-hat beam, a beam witha transverse power density distribution described by a Gaussian function, and for a series of truncated Gaussian beams. The diametersof the ablation craters were calculated assuming that the threshold ablation energy density was 3.5 J/cm2. The calculations and measurementswere performed for different beam energies and different distances of the sample from the focal plane. The paper describesa theoretical model, the results of numerical calculations, and the results of practical tests, which were compared with the results of thecalculations. Good agreement between the calculation and measurement results was obtained.