We built an ultra-low-noise angle sensor by combining a folded optical lever and a Sagnac interferometer. The instrument has a measured noise floor of 1:3 prad/√Hz at 2:4 kHz. We achieve this record angle sensitivity using a proof-of-concept apparatus with a conservative N = 11 bounces in the optical lever. This technique could be extended to reach subpicoradian//√Hz sensitivities with an optimized design.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics