  We investigate the wave effect in the gravitational lensing by a black hole
with very tiny mass less than 10^-19 solar mass, which is called attolensing,
motivated by a recent report that the lensing signature might be a possible
probe of a modified gravity theory in the braneworld scenario. We focus on the
finite source size effect and the effect of the relative motion of the source
to the lens, which are influential to the wave effect in the attolensing.
Astrophysical condition that the lensed interference signature can be a probe
of the modified gravity theory is demonstrated. The interference signature in
the microlensing system is also discussed.
