2.
The measurement of the M2 factor can be attributed to the beam measurement. of the beam width at different locations.
对M~2因子的测量可归结为对光束传输方向上不同位置的光束束宽的测量。
běn fā míng shè jí hán yǒu huáng niào lèi yào wù hé tā tīng lèi jiàng zhī yào wù de zǔ hé wù , shǔ yú yào xué lǐng yù 。