Iron phosphate glasses for optical uses - having high optical density in infrared and low optical density in visible light range

摘要

The glass contains (in wt.%) P2O5 70-77 (75.5), Fe3O4 5.0-7.5 (5.5-7.3) Al2O3 15.0-17.5 (16.0-16.5) B2O3 0-2 (0-1 esp. 0-0.5) ZnO 0-2.5 (1.5-2.5) and additionally Na2O 0-5, K2O 0-5, MgO 0-4, As2O3 0-0.5 and/or Sb2O3 0-2. The glass melt may opt. contain up to 2% C, Zn or (NH4) H2PO4 as a reducing agent. Discs made of this glass are used in projection appts. to protect the optical glass system against excessive heating. Spectacles made of it protect eyes against laser or infrared radiation of glowing metals in foundries, etc. Its selectivity is better than that of the known glasses of this type. The compsn. melts readily and bubble-free.