A cantilever-based measurement of short-range deviations from Newtonian gravity

We describe an apparatus for measuring deviations from Newtonian gravity down to a length scale of 20~$\mu$m. The apparatus consists of a cryogenic gas-bearing drive mass actuator used to excite the resonance of the test-mass-bearing microcantilevers. A Fabry-P\'{e}rot interferometer measures the cantilever position. An optical radiation pressure feedback system is used to adjust the cantilever Q$_{\mathrm{eff}}$ and T$_{\mathrm{eff}}$ without loss of measurement sensitivity. We discuss expected increases in detector sensitivity as a result of recent upgrades and future related experiments.