| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technique that enables a servo signal to be stably detected from a micro-holographic disk. <P>SOLUTION: The method includes detecting a primary signal of a reflected primary beam from a target data track of a target data layer of the holographic disk, where the primary beam of radiation has a first wavelength. The method also includes comparing a power measurement of the primary signal with a threshold value of power. The method also includes detecting a tracking signal of a reflected tracking beam from a reference layer of the holographic disk in an event that the power measurement of the primary signal is below the threshold value of power, where the tracking beam of radiation has a second wavelength. The method also includes generating a servo error signal based upon the primary signal or the tracking signal. The method further includes actuating an optical sub-system based upon either of the primary servo error signal or the tracking servo error signal such that the primary beam focuses on the target data layer. <P>COPYRIGHT: (C)2012,JPO&INPIT |
