In this paper, we purpose to use laser-induced microplasma occurred from a pyrographite target by laser ablation for microstruturing of fused silica plate to fabricate phase optical elements. Laser parameters for erosive plasma torch formation and subsequent etching of fused silica were determined based on preliminary experimental studies and estimated energy calculations. The influence of the overlap coefficients in the focal spot on the reproducibility of etching depths results and the deviation accuracy of etching depths with the found laser parameters was experimentally studied. The best results in terms of accuracy (no more than 0.1 μm) in deviations of etching depths are achieved with the overlap coefficient of 0.5. Moreover, the paper presents estimated calculations of the speed and efficiency of ablation, as well as the coefficient of energy conversion from laser radiation to the ablation energy of fused silica, which was ∼ 0.25. Based on achieved results an attempt was made to fabricate the 6-sector SPP for the wavelength of 355 nm.