| 摘要 |
A system for phase detection in page-based optical data storage involves a number of features that may be used individually or in combination to provide optimizations and to facilitate the heterodyne detection of the modulated readout signal beam. In one aspect, alignment sensors provide signals indicative of angular misalignment between the heterodyne reference beam and the signal beam, and a feedback control system aligns the reference beam with respect to the signal beam. In another aspect, a differential detection approach is utilized. In yet another aspect, a scanning approach is used wherein the reference beam is scanned over approximately a wavelength of phase difference to cause interference fringes to shift over the photodetector pixel array. Each pixel detects the signal at the phase value that cancels out localized variations of the wavefront, thus increasing the tolerance of the system to phase errors and to angular misalignments.
|
