  We describe a technique for fabricating micro- and nano-structures
incorporating fluorescent defects in diamond with a positional accuracy in the
hundreds of nanometers. Using confocal fluorescence microscopy and focused ion
beam (FIB) etching we first locate a suitable defect with respect to
registration marks on the diamond surface and then etch a structure using these
coordinates. We demonstrate the technique here by etching an 8 micron diameter
hemisphere positioned such that a single negatively charged nitrogen-vacancy
defect lies at its origin. This type of structure increases the photon
collection efficiency by removing refraction and aberration losses at the
diamond-air interface. We make a direct comparison of the fluorescence photon
count rate before and after fabrication and observe an 8-fold increase due to
the presence of the hemisphere.
