Benefits VSM at a glance
- Combination sensor Pirani / cold cathode
- The cold cathode sensor is automatically controlled by the Pirani
- Robust sensor design
- Overpressure stability of up to 16 bar abs.
Coating of mirrors
During the optical coating of mirrors for laser resonators, the process pressure is typically above 2e-3 mbar.
Challenge
A suitable vacuum transducer should continuously monitor both the process pressure during the coating and the final pressure of e-6 mbar in the vacuum chamber. Our client used to work with a Pirani/cold cathode combination gauge, the latter monitoring minimum and process vacuum. However, the continuous operation above e-3 mbar resulted in early wear and tear of the sensor.
Solution
In the VSM transducer the Thyracont Pirani with extended measuring range only activates the cold cathode at very low pressures. In addition, the transition between the two sensors can be configured according to the applications requirements. This way we achieved that the entire coating process is now monitored by the Pirani. The cold cathode is only actived when the appliance pumps down to minimum pressure. This protects the cold cathode and significantly improves process availability.
