Sapphire optical viewport for high pressure and temperature applications

We describe the design of a soldered sapphire optical viewport, which is useful for spectroscopic applications samples at high temperatures and pressures. The window bonded via active soldering to metal flange with structure two c-shaped rings made different metallic materials in between, so as mitigate thermally induced stress. A cell equipped viewports has been successfully operated alkali metals noble gas environment range 20–450 °C pressures from 10?6 mbar 330 bars. In upper pressure range, we observe leakage rate smaller than our readout accuracy 30 per day.