Beam quality measurement through off-axis optical vortex

One of the challenges for every optical system is preserving the quality of the used beam, which may be significantly reduced, due to the low condition of used optical elements or their misalignment. There are plenty of methods focused on the correction of the final beam, depending on the used entire optical system. The problem of efficient beam evaluation is just as important. So far, most of the measurements, are based on visual inspection, which is not always enough, especially when the high quality of the beam is required. Novel approaches use structured light to increase beam sensitivity for any imperfections. In this paper, we present an approach, which uses optical vortex shifted off-axis for a beam quality measurement. It uses SLM as a vortex generating element, which is shifted off-axis by proper hologram transformation. Tracking of the vortex trajectory may provide information about beam quality and aberration of an optical system. The new vortex localization algorithm will be presented.