Apparatus for maintaining in focus an image formed at the image plane of an optical instrument, notwithstanding random angular movement of the instrument's housing. Such apparatus includes mounting means for angularly decoupling the image-forming element (e.g., a refractive lens) of the optical instrument...http://www.google.fr/patents/US4290684?utm_source=gb-gplus-shareBrevet US4290684 - Image stabilizing apparatus
