全息光学头聚焦误差信号的理论及实验分析

A Theoretical and Experimental Analysis of the Focusing Error Signal in a Holographic Optic Head

讨论了全息光学头聚焦误差信号检测的基本原理。利用衍射理论推导出了全息光学头中光电探测器表面的光强分布，通过计算机模拟，得到光强分布随离焦量变化而变化的理论曲线，并对此进行了实验验证。

The principle of the detection of the focusing error signal in a holographic optic head is dis- cussed. Based on an analysis of the imaging process of the holographic optic head , a mathematical model for the system is developed. According to the diffraction theory , the light intensity distribution on the photodetector surface in the holographic optic head is derived. The theoretical curve of the light intensity distribution as a function of the focusing error is obtained through computer simulation. An experimental system of holographic optic head is set up and the test curve of the focusing servo signal is found to be in good conformity with the theoretical one. The results show that the novel holograph- ic optic element can be used to completely replace several conventional optic elements to provide the focusing error detection signals and realize the miniaturization of the optic head.