Durability of LiYF4

It has recently been brought to our attention that the LiYf4 (YLF) laser rods utilized in the alignment lasers of Nova tend to thin after several years of being exposed to the cooling water solution. As a consequence of this situation the YLF laser rods must occasionally be replaced. Since they found that they were able to minimize the dissolution rate for another fluoride crystal, Cr:LiSrAlF6 or Cr:LiSAF, by controlling the pH of the solution, they sought to determine if a similar fix could be applied to YLF laser crystals as well. For the case of Cr:LiSAF, the dissolution rate was observed to vary over 3 orders of magnitude depending on the pH, and a pH = 7 solution was determined to be optimal for improving the durability