The resonator stability depends on how well the sun is tracked. Clouds decrease the heating in the laser rod and cause the focal length to shift severely. Heliostat tracking displacements move the center of the absorption distribution inside the laser crystal. If the center of the thermal lensing moves, it acts as a resonator misalignment and less output is obtained. Future research will require more attention to keeping the laser stable with respect to the misalignment in heliostat tracking.
Clouds are unavoidable.
Using a resonator than ios more stable to a wide range of thermal focal lengths will give more consistent lasing. Since commercial laser systems have much more stable pump sources, it appears that space-based applications for solar lasers hold the most promise. Atmospheric effects are eliminated and the pump source is very stable. High brightness lasers can be built efficiently in space.