1. An optoelectronic surveillance system, comprising an acquisition unit including at least one sensor mounted behind a zoom having a group of movable lenses at the front and a group of fixed lenses at the rear, defining at least one first space in the convergent rays, and a control unit connected to the acquisition unit and to a rotary optical element arranged so as to rotate about a first axis and secured to a drive member controlled by the control unit in order to modify a field perceived by the sensor independently of a movement of the acquisition unit about the first axis, characterised in that the optical element is a first transparent plate mounted in the first space so as to rotate about the first axis, and the drive member is arranged so as to rotate the first optical plate in two opposite directions, the acquisition unit being mounted so as to turn about a second axis parallel to the first axis in a second rotation direction and the control unit is arranged so as to control the acquisition unit in order to capture images on the fly during the rotation of the acquisition unit about the second axis and the drive member in order to keep constant the field perceived by the sensor during a time of acquisition of at least one image.
2. A system according to claim 1, in which the first and second axes are substantially vertical.
3. A system according to claim 1 or 2, in which the group of fixed lenses delimits at least a second space with convergent rays in which at least one second transparent plate is mounted so as to turn about a third axis and is secured to a drive member arranged so as to

rotate the second transparent blade in two opposite directions and controlled by the control unit so as to modify a field perceived by the sensor independent of a movement of the acquisition unit about the third axis, the third axis being substantially perpendicular to the second axis.
4. A system according to claim 1, in which the control unit is arranged so as to control the rotation of the plate and the sensor in order to capture at least two successive images of the same scene portion and to add these images in order to obtain a reconstituted image with the same resolution as the successive images.
5. A system according to claim 1, in which the control unit is arranged so as to control the rotation of the plate and the sensor in order to capture successive images of the same scene portion.