Readout Optical System of Sapphire Disks intended for Long-Term Data   Storage
  The development of long-term data storage technology is one of the urging problems of our time. This paper presents the results of implementation of technical solution for long-term data storage technology proposed a few years ago on the basis of single crystal sapphire. It is shown that the problem of reading data through a substrate of negative single crystal sapphire can be solved by using for reading a special optical system with a plate of positive single crystal quartz. The experimental results confirm the efficiency of the proposed method of compensation. 
V.V.Petrov, V.P. Semynozhenko, V.M. Puzikov, A.A. Kryuchyn, A.S.   Lapchuk, S.M. Shanoilo, I.V.Kosyak, Yu. O. Borodin, I.V. ...
cs.ET physics.optics physics.pop-ph