Adaptive secondary mirrors at the Large Binocular Telescope recent updates

The two Large Binocular Telescope (LBT) Adaptive Secondary Mirror (ASM) units have been operating successfully since their installation in 2010/2011. Since that time, the two units have accumulated >25 years of combined operation on the telescope, which is remarkable given that these mirrors employ a relatively new technology. In this paper we will report statistics related to the operation of the LBT ASMs, including the operation time and down time, number and frequency of failing actuators and periodic maintenance campaigns. We will discuss the two main operational modes of these mirrors (seeing limited and AO operation) and the achieved performances, such as mirror optical flat and optical calibration quality, as well as the effect of telescope operational conditions such as: environmental conditions, telescope pointing and wind conditions; in particular, the wind effects and their implications, which drive some of the design requirements, will be reviewed and extensively discussed for the first time. Finally, we will report on the recent recoating of one of the three thin shells, which was done with a new and improved method. In comparison this new method is more safe, more reliable and less time consuming. We will describe the new hardware used for the thin shell coating and its interfacing to the ASM units as well as the procedural changes implemented.