光盘记录和回放系统以极高密度存贮信息。不论单面或双面光盘都由螺旋形槽纹构成,槽纹具有V形或倒梯形截面。槽面两边可作记录轨迹使用,使轨迹节距减少到单边轨迹的一半。使用V形预刻槽轨迹,光盘记录密度可比常规记录视盘密度高一倍,视频信息贮存在两个倾斜表面上, Compact disc recording and playback systems store information at very high density. Whether single-sided or double-sided discs are composed of spiral groove, groove has a V-shaped or inverted trapezoidal cross-section. Both sides of the groove surface can be used as recording tracks to reduce the track pitch to half of the unilateral tracks. Using a V-shaped pre-groove track, the disc recording density can be twice as high as that of a conventional video disc, the video information is stored on two inclined surfaces,