High-precision mechanism for on-sky optical beam divergence adjustment (artes 4.0 sl spl 6c.080) - expro+ (on request)

Objective: The objective of this activity is to develop and test a mechanism for an optical ground station that can adjust the beam's divergence during the link sessionwithout link interruption and whilst maintaining the optical pointing accuracy.TargetedImprovements:To enable dynamic adjustment of the beam divergence without needing optical realignment. This will enable real-time optimisation of the link based onthe elevation angle and the turbulence conditions. Eventually, integrating the beacon capabilities with the communications beam.Description: Alignment of the optical system at an optical ground station is usually needed before a link session, especially if the optical configuration (beam divergence)has changed. Links to Low-Earth Orbit are highly dynamic, ranging for very small elevation angles up to zenith, and atmospheric turbulence conditionsevolving during a link session. It is essential that for links targeting optical feeder applications the ground-space connectivity must be maintained.Furthermore, ground-to-space links usually make use of a beacon during the acquisition phase. For these reasons, developing a mechanism that allowsfor real-time beam-divergence adjustment without the need to re-align the optical components is considered very useful.Some of the off-the-shelf components used in optical ground stations are limited in accuracy and optical power, and therefore not suitable for an on-skyreal-time adjustment of the beam divergence. This activity shall evaluate the state-of-the-art of mechanisms, with their limitations on accuracy, precisionand maximum supported power. The design and development of an engineering model shall demonstrate the capabilities of the mechanism. This goalcan be achieved either in the laboratory with realistic interfaces or at an optical ground station.