Coating Of Mirrors With Aluminium And Its Advantages In Astrophysical Research.

Deposition of Al vapours on mirrors in vacuum can now be applied to even larger surfaces sp that investigations in the ultraviolet spectrum range up to a (formula) are now possible with large reflector instruments, especially for spectrolheliograms in the light of the red H line Ha and of the ultraviolet line (formula) as Al has a much greater reflectivity than Ag and keeps the reflectivity longer.