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本文叙述了具有两个自由度的数字式音乐唱片的光学拾音头系统(TAOHS)并与其它系统进行了比较。音频信号、调焦误差信号和跟踪误差信号来自于四象限光电二极管的四个输出端,此光电二极管用来探测从唱片表面反射并透过物镜和临界角反射棱镜的单激光束的强度分布。本文还讨论了误差信号的来源和唱片倾斜的影响。伺服机构控制物镜在平行和垂直于光轴的两个方向上独立移动来实现自动调焦和跟踪,这种光学探头的尺寸很小,因此它易于适应使用密纹唱片(CD)的唱机。本文还讨论了对光学元件的要求。
This article describes the Optical Pickup Head System (TAOHS) for digital music recordings with two degrees of freedom and compares them with other systems. The audio signal, the focus error signal and the tracking error signal come from the four outputs of a four-quadrant photodiode used to detect the intensity distribution of a single laser beam reflected from the disc surface and transmitted through the objective lens and the critical angle reflection prism. This article also discusses the sources of error signals and the effects of record skew. The servo controls the objective to move and focus independently in both directions parallel and perpendicular to the optical axis. The optical probe is small in size and therefore easily adaptable to record players using Compact Discs (CDs). This article also discusses the requirements for optical components.