• Process monitoring
• Monitoring final pressure

The optical coating of mirrors for laser resonators is a crucial process to optimize the performance and efficiency of a laser. The mirror coatings are used to control the reflective properties of the mirrors and to meet the specific requirements of the laser.

During the optical coating of mirrors for laser resonators, the process pressure is typically above 2e-3 mbar.

Requirements

Suitable vacuum gauges must continuously monitor both the process pressure and the final pressure of 10-6 mbar in the vacuum chamber. Our customer originally used a combination of a Pirani and a cold cathode for this purpose, with the latter also monitoring the process. However, constant operation above 10-3 mbar quickly led to premature wear.

Suitable Products

VSM: In the VSM digital vacuum transmitter, a combination of Pirani and cold cathode sensors measures absolute pressure from atmosphere to ultra-high vacuum. The Thyracont Pirani with extended measuring range only switches on the cold cathode sensor at very low pressure. In addition, the transition between Pirani and cold cathode can be individually configured. This means that the Pirani monitors the entire coating process, while the cold cathode is only activated when the final pressure is reached. This protects the cold cathode and significantly improves process availability.