Optical microphone to diagnose actuators

A diagnostic system to function-monitor an actuator to affect a process medium stream of a process engineering plant, comprising:

• an optical microphone allocated to the actuator and arranged in a conduit of the process engineering plant that leads the process medium stream, the optical microphone being orientated to an inside of a housing of the actuator, wherein the optical microphone is configured to:
• measure an acoustic, actuator-specific operating signal, as leakage sound and cavitation sound, based on electromagnetic radiation that is affected by the acoustic, actuator-specific operating signal, and
• generate an electrical measuring signal based on the measured acoustic, actuator-specific operating signal;
• and
• diagnostic electronics that are configured to receive and store, process, and/or transmit the electrical measuring signal.

A diagnostic system to function-monitor an actuator to affect a process medium stream of a process engineering plant, comprising:

• an optical microphone allocated to the actuator and configured to:
• measure an acoustic, actuator-specific operating signal, as leakage sound and cavitation sound, based on electromagnetic radiation that is affected by the acoustic, actuator-specific operating signal, and
• generate an electrical measuring signal based on the measured acoustic, actuator-specific operating signal;
• and
• diagnostic electronics that are configured to receive and store, process, and/or transmit the electrical measuring signal, wherein the optical microphone includes an arrangement of at least two optical sub-microphones configured to generate respective measuring signals to conduct a three-dimensional resolution of a sound field of the acoustic, actuator-specific operating signal, the arrangement of at least two sub-microphones being configured to perform the three dimensional resolution of the sound field in such a way that the arrangement localizes a sound source and/or determines the sound velocity.