The invention provides a super-resolution three-dimensional
optical storage focusing
servo device and a
servo method thereof. The device integrates a
light source shaping module, a beam combining module, a zooming layer selection module, a
servo signal detection module and a driving control module. The
solid excitation light and the hollow suppression light are combined to form coaxial recording light, the servo objective lens and the recording objective lens are controlled to move axially by using a
signal generated by reflecting the
solid servo light by the servo guide layer, and the centers of double light beams are always kept aligned in the read-write process, so that high-speed nano focusing servo is realized. An additional servo
light source is not needed, double-beam focuses are adjusted in real time to keep three-dimensional alignment, the
diffraction limit is exceeded, and the storage density is improved. The lens group is combined to compensate aberration,
zoom and skip
layers, so that hundred-layer ultra-high-density storage is realized. The device is simple in structure, convenient to operate and good in compatibility, is applied to the field of super-resolution three-dimensional
optical storage, and has a wide application prospect.