Fixing device for an optical unit comprising shock absorbers for a pedestrian impact

The device has a strap (30) fixed on a unit of a vehicle structure and engaged in a slider (20) connected to an optical unit. The optical unit is to be displaced longitudinally towards back in case of shock on front side of the vehicle by sliding the slider against the strap. The slider has a longitudinal portion (21) in which the strap is engaged, and an inclined portion extending the portion (21) towards front and top of the vehicle.