  We investigate the optical detection of single atoms held in a microscopic
atom trap close to a surface. Laser light is guided by optical fibers or
optical micro-structures via the atom to a photo-detector. Our results suggest
that with present-day technology, micro-cavities can be built around the atom
with sufficiently high finesse to permit unambiguous detection of a single atom
in the trap with 10 $\mu$s of integration. We compare resonant and non-resonant
detection schemes and we discuss the requirements for detecting an atom without
causing it to undergo spontaneous emission.
