An imaging medical apparatus has at least one device to identify a plane in space. The device has: a light source that emits a fan-shaped light beam, the light source is rotatable around a light source rotation axis. The device also has a mirror that reflects the fan-shaped light beam, the mirror being rotatable around a mirror rotation axis and encompassing a mirror plane. The mirror rotation axis and the surface normal of the mirror plane enclose an angle greater than 0° and less than 90°.
