而在不同纵向位置，这些同心环的强度分布是不同的，且是周期性变化的。
However in different longitudinal position, the intensity distribution of these rings is different and varies periodically.
而在不同纵向位置，这些同心环的强度分布是不同的，且是周期性变化的。
However in different longitudinal position, the intensity distribution of these rings is different and varies periodically.
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