在 VCD和 DVD中由于使用了全息光学元件 ,全息光学读出头的元件数量比传统光头的元件数量少 .分析了光盘信号探测、聚焦、循迹原理 .推出了光栅衍射效率的一般计算公式 ,并给出了光栅沟槽形状为“方波”时光栅衍射效率的计算公式 ,由此计算出了 VCD和 DVD实用的全息光学元件的蚀刻深度 Due to the use of holographic optical elements in VCD and DVD, the holographic optical pickup has fewer components than traditional optical pickups, and the principle of optical disk signal detection, focusing and tracking is analyzed. A general formula of grating diffraction efficiency is proposed. The calculation formula of the grating diffraction efficiency when the grating groove shape is “square wave” is given, from which the etching depth of the practical holographic optical element of VCD and DVD is calculated