采用可变多分隔模式的新型单光束检测方法

Novel one-beam detection method with changeable multi division patterns

一、引言BD(Blu-ray Disc)是目前主流的高密度蓝光光盘格式,它采用405nm的激光波长和0.85的数值孔径,实现了单层25GB的存储容量。BD家族包括ROM (只读)/R(可录)/RE(可重写)等格式,以及标准容量为50GB的单面双层BD光盘。对于可录系统中的循迹误差信号,传统的三光束差分推挽法(DPP:Differential Push-Pull)

We developed a new one-beam detection method with changeable multi division patterns,pairing with tangential spot size detection(SSD)method for focusing error detection.The changeable multi division patterns are realized by, the active device,which consists of a non-polarizing HOE for tangential SSD method,liquid crystal(LC)active rotator and two different division patterns of layered polarizing blazed HOEs.The LC active rotator properly acts as the mode selector and an R/RE mode pattern for one-beam push-pull method and a ROM mode pattern for differential phase detection(DPD)method can be selected only changing the applied voltage.The newly developed system can derive one- beam push-pull signal,DPD signal,wobble signal and RF signal from the output only from five common photo detectors. Sufficient quality of these signals is experimentally confirmed.