So, if the disk is too far away -- then quadrants D and B will get more light than quadrants A and C.Similarly, if the disk is too close -- then quadrants A and C will get more light than D and B.

• 所以，当光盘太远，像限D和B中将比A和C得到更多的光，同样的，如果光盘太近，像限A和C中将比D和B得到更多的光。