Instrumented baffle for the Advanced Virgo input mode cleaner end mirror

A novel instrumented baffle surrounding the suspended end mirror in the input mode cleaner cavity of the Virgo interferometer was installed in Spring 2021. Since then, the device has been regularly operated in the experiment, and the data collected show good stability. The baffle will operate in the upcoming O4 observation run, serving as a demonstrator of the technology designed to instrument the baffles in front of the main mirrors in time for O5. In this paper, we present a detailed description of the baffle design, including mechanics, front-end electronics, and data acquisition as well as optical and vacuum compatibility tests, calibration and installation procedures, and performance results.