  Advances in infrared nanoscopy have enabled access to the finite momentum
optical conductivity $\sigma(\vec{q},\omega)$. The finite momentum optical
conductivity in graphene has a peak at the Dirac fermion quasiparticle energy
$\epsilon(k_F-q)$, i.e. at the Fermi momentum minus the incident photon
momentum. We find that the peak remains robust even at finite temperature as
well as with residual scattering. It can be used to trace out the fermion
dispersion curves. However, this effect depends strongly on the linearity of
the Dirac dispersion. Should the Dirac fermions acquire a mass, the peak in
$\sigma(q,w)$ shifts to lower energies and broadens as optical spectral weight
is redistributed over an energy range of the order of the mass gap energy. Even
in this case structures remain in the conductivity which can be used to
describe the excitation spectrum. By contrast, in graphene strained along the
armchair direction, the peak remains intact, but shifts to a lower value of $q$
determined by the anisotropy induced by the deformation.
