Read head and methods for reading multilayer optical data storage media

Abstract

Provided are a read head and methods for reading a multi-layered optical data storage medium comprising a transparent substrate having layers of voxels embedded therein. The read head comprises an imaging system for capturing images of groups of voxels, wherein the read head is configured to bring the imaging system into focus on variable depths in a multi-layered optical data storage medium; and an autofocus system for identifying depth positions of voxels in the multi-layered optical data storage medium by sampling an area in the optical data storage medium. The autofocus system comprises a light source for illuminating the area; and a detector for detecting light from the light source transmitted through the multi-layered optical data storage medium. A method of reading data from a multi-layered optical storage medium comprises capturing, using an imaging system, images of sectors in a first track. The multi-layered optical data storage medium and imaging system are held at fixed lateral positions during the capture of the images.