Pressure-proof probe

A probe for monitoring a pressurised process space in which one or more hazardous substances occur, the probe comprising:

• a casing enclosing a first cavity and having a first window, configured to be brought into contact with the pressurised process space, the first window having a first pressure-tight seal formed between the first cavity and the pressurised process space, and a second window having a second pressure-tight seal formed between the first cavity and a second cavity which is sealed off from the pressurized process space, preventing passage of the one or more hazardous substances to the second cavity, wherein the first pressure-tight seal and the second pressure-tight seal are positioned in the casing to form the cavity;
• a first coupling line disposed within the cavity between the first and second windows and configured to guide electromagnetic radiation entering through one of the two windows to the other of the two windows;
• a first lens disposed between the first coupling line and the first window;
• a second lens disposed between the first coupling line and the second window;
• a second coupling line positioned in the secondary cavity and disposed on an opposite side of the second window from the first coupling line, the second coupling line configured to guide electromagnetic radiation to or from the first coupling line;
• and
• a third lens positioned in the secondary cavity and disposed between the second coupling line and the second window, wherein the second and third lenses optically couple electromagnetic radiation between the first and second coupling lines through the second window.