If the optical head is on track, then the primary beam will be centered on a track (with pits and bumps) and the two secondary beams will be centered on land.
如果光学头在轨道上，主激光束将处于轨道中心，两个副光束处于轨道之间。
2
Such point existing in the inclined plane of m type cage inclined beam place, it is more reasonable to use the inclined beam place as land riding place.