Microscopic diamond Solid-Immersion-Lenses fabricated around single   defect ceneters by focussed ion beam milling
  Recent efforts to define microscopic solid-immersion-lenses (SIL) by focused ion beam milling into diamond substrates that are registered to a preselected single photon emitter are summarized. We show how we determine the position of a single emitter with at least 100 nm lateral and 500 nm axial accuracy, and how the milling procedure is optimized. The characteristics of a single emitter, a Nitrogen Vacancy (NV) center in diamond, are measured before and after producing the SIL and compared with each other. A count rate of 1.0 million counts per second is achieved with a $[111]$ oriented NV center. 
Mohammad Jamali, Ilja Gerhardt, Mohammad Rezai, Karsten Frenner,   Helmut Fedder, and J\"org Wrachtrup
physics.optics cond-mat.mtrl-sci quant-ph