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. 本发明涉及一种兼容BD和CBHD读写的物镜，其中包括为自由曲面的入光面和为平坦非球面的出光面，平行激光光束依次经过所述入光面和所述出光面分别在BD信息层处和CBHD信息层处形成衍射极限级聚焦光斑。本发明还涉及一种兼容BD和CBHD读写的光学头以及光盘读写装置。本发明的兼容BD和CBHD读写的物镜、光学头以及光盘读写装置采用自由曲面技术，增长物镜的工作距离，以降低对物镜装配精度的要求，成品率高，成本低，不需要人为调整物镜的数值孔径。