An overview of isolation controls at LIGO

Abstract

The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment that aims at measuring gravitational waves emitted by astrophysical sources. The detection of black hole mergers and neutron star collision was made possible by the extreme level of isolation required to hold the optics still from external ground disturbances in a large band of the spectrum. From the low-frequencies (earthquakes, wind, microseism, below 1 Hz) to the higher frequencies (anthropogenic noise, above 1 Hz), the controls system must be tuned to meet the requirements for lock acquisition, lock stability, and sensitivity of the instrument. In this talk, I will describe the overall control scheme of the LIGO isolation platforms and mirror suspensions, and the challenges met to design the many feedback and feedforward control loops.The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment that aims at measuring gravitational waves emitted by astrophysical sources. The detection of black hole mergers and neutron star collision was made possible by the extreme level of isolation required to hold the optics still from external ground disturbances in a large band of the spectrum. From the low-frequencies (earthquakes, wind, microseism, below 1 Hz) to the higher frequencies (anthropogenic noise, above 1 Hz), the controls system must be tuned to meet the requirements for lock acquisition, lock stability, and sensitivity of the instrument. In this talk, I will describe the overall control scheme of the LIGO isolation platforms and mirror suspensions, and the challenges met to design the many feedback and feedforward control loops.