  This paper deals with the control of laser spot in the context of minimally
invasive surgery of the middle ear, e.g., cholesteatoma removal. More
precisely, our work is concerned with the exhaustive burring of residual
infected cells after primary mechanical resection of the pathological tissues
since the latter cannot guarantee the treatment of all the infected tissues,
the remaining infected cells cause regeneration of the diseases in 20%-25\-% of
cases, which require a second surgery 12-18 months later. To tackle such a
complex surgery, we have developed a robotic platform that consists of the
combination of a macro-scale system (7 degrees of freedom (DoFs) robotic arm)
and a micro-scale flexible system (2 DoFs) which operates inside the middle ear
cavity. To be able to treat the residual cholesteatoma regions, we proposed a
method to automatically generate optimal laser scanning trajectories inside the
regions and between them. The trajectories are tacked using an image-based
control scheme. The proposed method and materials were validated experimentally
using the lab-made robotic platform. The obtained results in terms of accuracy
and behaviour meet perfectly the laser surgery requirements.
