parallel beam

• 平行光束,平行束

parallel beam的用法和样例：

例句

1. The parabolic reflector of a searchlight gives a parallel beam.
   探照灯的抛物面反射镜发出平行光束。
2. Under astigmatism even narrow parallel light beams will not combine into one point.
   有象散存在时甚至很窄的平行光束都不能会聚在一点。