  Topological superconductors, such as noncentrosymmetric superconductors with
strong spin-orbit coupling, exhibit protected zero-energy surface states, which
possess an intricate helical spin structure. We show that this nontrival spin
character of the surface states can be tested experimentally from the absence
of certain backscattering processes in Fourier-transform scanning tunneling
measurements. A detailed theoretical analysis is given of the quasiparticle
scattering interference on the surface of both nodal and fully gapped
topological superconductors with different crystal point-group symmetries. We
determine the universal features in the interference patterns resulting from
magnetic and nonmagnetic scattering processes of the surface quasiparticles. It
is shown that Fourier-transform scanning tunneling spectroscopy allows us to
uniquely distinguish among different types of topological surface states, such
as zero-energy flat bands, arc surface states, and helical Majorana modes,
which in turn provides valuable information on the spin and orbital pairing
symmetry of the bulk superconducting state.
