Objective lens, optical pickup head and compact disc reading-writing device compatible with reading and writing of blue-ray disc (BD) and China blue high-definition disc (CBHD)

Abstract

The invention relates to an objective lens compatible with the reading and writing of a blue-ray disc (BD) and a China blue high-definition disc (CBHD). The objective lens comprises an incident surface and an emergent surface, wherein the incident surface is a free curved surface; and the emergent surface is a flat aspheric surface. Parallel laser beams sequentially pass through the incident surface and the emergent surface, and form diffraction limit-level focal spots on a BD information layer and a CBHD information layer. The invention also relates to an optical pickup head and a compact disc reading-writing device, which are compatible with the reading and writing of the BD and the CBHD. According to the objective lens, the optical pickup head and the compact disc reading-writing device compatible with the reading and writing of the BD and the CBHD, a free curved surface technology is adopted, and the working distance of the objective lens is prolonged, so that requirements for the assembly accuracy of the objective lens are lowered, the objective lens is high in yield and low in cost, and the numerical aperture of the objective lens is not required to be manually regulated.

Description

technical field [0001] The invention relates to the field of optical storage, and more specifically relates to an objective lens compatible with BD and CBHD reading and writing, an optical head and an optical disc reading and writing device. Background technique [0002] There are optical heads required to read and write BD (Blu-ray Disc: Blu-ray Disc) and CBHD (China Blue High-definition Disc: China High-definition Blu-ray Disc) disc information, which can generate numerical aperture at the corresponding disc information layer Diffraction-limited focused spots of 0.85 and 0.65, respectively. However, since the laser wavelength required by both optical discs is 405nm, the existing objective lenses used for BD, DVD, and CD compatibility or CBHD, DVD, and CD compatible objective lenses cannot realize the compatibility of BD and CBHD alone. There are currently two mainstream technologies to solve the compatibility problem of BD and CBHD: 1. Adopt dual objective lens optical he...

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is to provide a high-reading and writing cost for the dual objective lens device compatible with BD and CBHD in the prior art or the difficulty in cooperation between the objective lens and the beam selection element due to the numerical aperture control of the single objective lens. BD and CBHD compatible objective lens, optical head and optical disk reading and writing device with free-form surface technology, low precision requirements and high yield

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