Multilayer optical disk focused oblique incidence Fuke prism method

Abstract

An oblique-incidence Foucault prism method for multi-layer optical disc focusing, the focusing device involved is: the laser light emitted by the laser and collimated is focused by the incident lens and enters the optical disc surface in a way that the optical axis is inclined relative to the optical disc surface, After being reflected on the information recording surface of the optical disc, it is focused and imaged by a reflective lens, and then through the Foucault prism set at the imaging point, the defocus signal is formed by receiving the light spot through a two-quadrant photoelectric receiver; the method is as follows: 1) Make the optical disc away from the laser The position of the focal point moves toward the laser focal point to realize coarse focusing; 2) The laser beam forms a light spot on the surface of the two-quadrant photoelectric receiver through the above-mentioned focusing device; 3) Let the defocus signal T be the upper quadrant photocurrent of the two-quadrant photoelectric receiver and the ratio of the difference between the photocurrent of the lower quadrant and the total photocurrent; 4) change the position of the two lenses with T to control the two-dimensional torque device of the position of the two lenses to reduce the amount of defocus; 5) repeat the above 2) to 4) process until the accurate focused illumination of the laser focus point on the information recording surface of the optical disc is realized.

Description

technical field [0001] The invention relates to the optical storage technology, in particular to a focusing method using a Foucault prism when reading and writing the optical storage of a multilayer optical disc. Background technique [0002] High-density and large-capacity data storage is a key research field in information science. The next generation of ultra-high-density optical memory will be based on near-field optical storage technology that breaks through the diffraction resolution limit or three-dimensional optical volume storage technology that breaks through the plane limit of optical discs. Among them, there are two main methods of three-dimensional optical storage: one is holographic volume storage, and the other is multi-layer bit storage. Holographic volume storage is still far away from practical large-capacity data storage because of its bit error rate is difficult to control. Multi-layer bit storage is the only possible way to realize three-dimensional opti...

AI Technical Summary

Problems solved by technology

However, for multi-layer optical discs, the reflected light of each layer is superimposed on the same four-quadrant detector and cannot be distinguished, so it is impossible to focus on each layer

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