  Franz-Keldysh oscillations of the optical absorption in the presence of
short-range disorder are studied theoretically. The magnitude of the effect
depends on the relation between the mean-free path in a zero field and the
distance between the turning points in electric field. Damping of the
Franz-Keldysh oscillations by the disorder develops at high absorption
frequency. Effect of damping is amplified by the fact that, that electron and
hole are most sensitive to the disorder near the turning points. This is
because, near the turning points, velocities of electron and hole turn to zero.
