光学头安装误差对循迹信号的影响

Influence of Optical Pick-up Assembly Error on Tracking Signal

光学头的安装误差导致盘片轨道与光电探测器的切向轴线存在夹角，在光盘标量衍射模型的基础上，引入光学头出瞳上的旋转角度误差参数，根据CDIROM和DVDIROM的盘片参数，计算并分析了旋转误差对三光束法和差动相位检测（DPD）法循迹信号的影响。计算结果表明：旋转误差使三光束法循迹信号的幅值近似呈周期性变化，它是在生产过程中需要严格控制的参数以保证循迹信号的幅值最大化；旋转误差在0～25°范围内时，对DPD信号幅值影响较小，在25°～45°时，使DPD信号的幅值降低，大于45°时，使DPD信号的极性发生变化。

The optical pick-up assembly error causes photo detector integrated circuit （PDIC） rotation angle from the disk track direction. The influence of the rotation angle on tracking signal is analyzed and computed based on the optical disk scalar diffraction model. The rotation angle approximately periodically changes the sub-beam signal amplitude and should be strictly controlled in the assembly to maximize the tracking signal amplitude. The differential phase detection（DPD） signal amplitude is less suffered from the rotation angle if the angle is less than 25°. If the angle is within 25°～ 45° the amplitude is decreased. If the angle is within 45°～90°,the DPD signal polarity is inversed.