Contamination monitoring in a laser system using a surface acoustic wave device

In this study, the environment inside an operational laser system was monitored over a period of three months using a surface acoustic wave sensor. The environment experienced by the sensor was subject to repeated vacuum pumpdown, nitrogen purge and chemical flow processes. The data collected during this period demonstrated the fact that this type of sensor is subject to both accumulation and desorption mechanisms. Surface conditions were clearly active and changing over time. By tailoring the sensor surface to be equivalent to that of the optical coatings in the system, it was believed that the sensor provided an excellent view of the condition of the surface of those optical coatings. Monitoring a system using a device of this type may, in the near term provide some knowledge of readiness. In the long term, this type of monitoring may assist in the selection of compatible materials and effective design for control of contamination.