Multimode characterization of an optical beam deflection setup

Alex Fontana and Ludovic Bellon, accepted for publication in Phys. Rev. App. (2024)

arXiv: 2402.04887
[dataset] doi: 10.5281/zenodo.11110783

Optical beam deflection is a popular method to measure the deformation of micro-mechanical devices. As it measures mostly a local slope, its sensitivity depends on the location and size of the optical spot. We present a method to evaluate precisely these parameters, using the relative amplitude of the thermal noise induced vibrations. With a case study of a micro-cantilever, we demonstrate the accuracy of the approach, as well as its ability to fully characterize the sensitivity of the detector, and the parameters (mass,
stiffness) of the resonator.