  Gravitational lensing is a well known phenomenon predicted by the General
Theory of Relativity. It is now a well-developed observational technique in
astronomy and is considered to be a fundamental tool for acquiring information
about the nature and distribution of dark matter. In particular, gravitational
lensing experiments may be used to search for black holes. It has been proposed
that a Schwarzschild black hole may act as a retro-lens (Holz & Wheeler
\cite{hw}) which, if illuminated by a powerful light source (e.g. the Sun),
deflects light ray paths to large bending angles so that the light may reach
the observer. Here, by considering the strong field limit in the deflection
angle and confining our analysis to the black hole equatorial plane, we extend
the Holz-Wheeler results to slowly spinning Kerr black holes. By considering
the Holz-Wheeler geometrical configuration for the lens, source and observer we
find that the inclusion of rotation does not substantially change the
brightness of the retro-lensing images with respect to the Schwarzschild case.
We also discuss the possibility that the next generation space-based telescopes
may detect such retro-images and eventually put limits on the rotational
parameter of the black hole.
