  Levitated dipolar scatterers exhibit exceptional performance as
optomechanical systems for observing quantum mechanics at the mesoscopic scale.
However, their tendency to scatter light in almost any direction poses
experimental challenges, in particular limiting light collection efficiencies
and, consequently, the information extractable from the system. In this
article, we present a setup designed to enhance the information gleaned from
optomechanical measurements by constraining the back action to a specific
spatial direction. This approach facilitates achieving Heisenberg-limited
detection at any given numerical aperture. The setup consists of a hollow
hemispherical mirror that controls the light scattered by the dipolar emitter,
particularly at high scattering angles, thereby focusing the obtained
information. This mirror is compatible with existing setups commonly employed
in levitated optomechanics, including confocal lenses and optical resonators.
