light-centre length

例句：

1. 1.The light-centre length of the beam is 50 cm.
   光束的光轴长度为50厘米。
2. 2. The design of the light-centre length is very important.
   光轴长度的设计非常重要。
3. 3. The light-centre length of the beam can be adjusted by changing the lens aperture.
   通过改变透镜孔径可以调整光束的光轴长度。