METHOD OF DETECTING THE STATE OF AN OPTICAL ELEMENT AND LASER ARRANGEMENT WITH A DEVICE FOR DETECTING THE STATE OF AN OPTICAL ELEMENT

摘要

A condition or detecting a change in the condition of an optical element of a laser arrangement is detected. An ultrasonic signal is coupled into an optical element such that the ultrasonic signal travels along a path within the optical element, and a transit time or a change in transit time for the ultrasonic signal to travel along the path within the optical element is detected.