该方法借助一个焦距较长的凸透镜与被测凹透镜组成无焦系统，可以使准直管出射光束的张角发生改变；

Firstly, a telescope system is made up with a concave lens and a long-focus convex lens, by which the angle of the parallel beam from the collimator can be change.

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该方法借助一个焦距较长的凸透镜与被测凹透镜组成无焦系统，可以使准直管出射光束的张角发生改变；

Firstly, a telescope system is made up with a concave lens and a long-focus convex lens, by which the angle of the parallel beam from the collimator can be change.

youdao