Speaker
Description
Angular sensing and control (ASC) is essential for the Einstein Telescope (ET), and its design is one of the big challenges for the low-frequency interferometer of ET (ET-LF), because ASC would inject unwanted control noise originating from the noise of sensors used for ASC. The requirements for the ASC should be set so that the control noise doesn't exceed the ET-LF design sensitivity, and we need to investigate the requirements from both the suspension design and the interferometer control design perspectives.
We, the Low-Frequency Control Noise Work Package, aim to investigate these requirements using simulations. A Fabry-Perot Michelson Interferometer (FPMI) Finesse model with realistic suspensions is being developed in communication with experts from the Suspension Division and the Interferometer Division. With such a model, we can probe the coupling from the angular control noise to the main interferometer degree of freedom (DARM) for a given beam offset and set requirements on the combination of the beam spot offset and the angular sensing noise. In this presentation, we will show the progress of the model from a simple Fabry-Perot cavity towards a realistic Dual-Recycled FPMI, and updated requirements for the beam spot offset and sensing noise.