Sugaya S, Mansuripur M
Appl Opt. 1994 Aug 1;33(22):5073-9. doi: 10.1364/AO.33.005073.
Using computer simulations based on the diffraction theory of high-N.A. systems, we examine the effects of substrate birefringence on servo signals in magneto-optical disk drives. Our attention is confined to systems that use the methods of push-pull tracking and astigmatic focus-error detection. We show that the amounts of birefringence typically observed in polycarbonate substrates do not in themselves cause problems for the servo channels. However, the presence of residual aberrations in the optical path (astigmatism in particular) can have devastating effects on the magnitude of the track-error signal and the stability of the focusing servo. We show that the combination of substrate birefringence and residual beam astigmatism can either improve or deteriorate the performance of the focusing servo, depending on the orientation of the aberration relative to the principal axes of the substrate.
利用基于高数值孔径系统衍射理论的计算机模拟，我们研究了磁光盘驱动器中衬底双折射对伺服信号的影响。我们的研究重点局限于采用推挽跟踪和像散聚焦误差检测方法的系统。我们表明，聚碳酸酯衬底中通常观察到的双折射量本身不会给伺服通道带来问题。然而，光路中残余像差（特别是像散）的存在会对跟踪误差信号的幅度和聚焦伺服的稳定性产生毁灭性影响。我们表明，衬底双折射和残余光束像散的组合可以改善或恶化聚焦伺服的性能，这取决于像差相对于衬底主轴的方向。
