Speaker
Description
Compact displacement sensors with sub-picometer level performance between 0.01Hz and 100Hz are a crucial technology for future detectors, detector upgrades and inertial sensors to reduce noise in suspension control and test-mass sensing. We are investigating sensors based on Deep-Frequency Modulation Interferometry (DFMI) for this purpose at the University of Hamburg and we will present our status on all relevant aspects. This includes the development our optical sensing head, which combines on-axis sensing with ghost beam suppression and balanced readout. We also discuss a new readout algorithm that provides optimal phase and absolute ranging estimation with minimal processing delays, enabling us to implement dozens of sensors in the future. We present the current testing and performance results achieved in table-top experiments and discuss the identified limitations and future improvements. We also present our seismic isolation platform that we will use to test the sensors on suspensions in vacuum and its commissioning status. Finally, we discuss our model for the fundamental readout limitations of DFMI-based sensors and how we are working to overcome this limitation to reach sub-femtometer precision in future sensor iterations by using resonant enhancement in combination with DFMI.
