I am helping one of my old physics professor and his Phd design a low-atmospheric vacuum chamber and we're looking at different materials to prevent outgassing. However the tank is almost 1m long and all the equipment inside must be taken out and checked after each test. It would be nice if we could see in to see which components aren't working or that need to be replaced. Is there a material out there that is transparent and has a minimal outgassing rate? The vacuum chamber must reduce to less than 10^-7 torr. Thanks!