A probe is set to receive a thin film of Aluminum via a thermal evaporation vacuum system. The reason to coat the fiber in the vacuum system is to create a clean surrounding for the coating process. The thermal evaporation vacuum system includes a main chamber, ion gauge, roughing valve, high vacuum valve, fore-line valve, diffusion pump, mechanical pump, flow switch, heat sink, solid state relay, neutral bus, solenoid valves, and ammeter.
It is highly necessary to maintain an interlock for the diffusion pump by using the flow switch and solid state relay. The interlock is needed to prevent damage on the diffusion pump. Specifically, if there is not enough water passing through the flow switch, the diffusion pump cannot be turned on. The diffusion pump needs water when pumping vapor cycle and gas flow inside the system. The diffusion pump, VHS-6, is operated at 120 Volts with the solid state relay controlled by a 24 Volts power supply. Therefore, a solid state relay is designed to switch the power for the load circuitry of the diffusion pump. The neutral bus is technically allowed to bond the wires of the system. This thermal evaporation vacuum system is used to coat a thin layer of Aluminum on an optical fiber. Everywhere except the tip of the optical fiber has been covered in a thin layer of Aluminum.