在迈克尔逊干涉仪的一支光路中,放入一片折射率为n的透明介质薄膜后,测出两束光的光程差的改变量为一个波长λ,则薄膜的厚度是( )。
A <img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251114/23412819_0.png"> B
<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251114/23412819_0_1.png"> C
<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251114/23412819_0_2.png"> D
<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251114/23412819_0_3.png">