某同学测量一块形状不规则，体积较大的矿石的密度．

阅读下列材料，按要求完成各题。

    This is Mr. Wilson's room. It's clean and tidy. It looks like（像） a nice picture. The walls are white and the window is big. You can see a photo of his family and a photo of his girlfriend on the wall. His girlfriend is Peggy Carmen. A yellow desk is near the window. You can see some green plants and five colorful flowers on it. A blue clock is on it, too. It is seven now. A baseball is under his bed. His T-shirt and his bag are on the bed. Look! What's that in the drawer(抽屉) of the desk? Oh, it's Mimi, a cat. It's black. It looks like a hat.

下列说法正确的是    （   ）

要使某透镜能对在空气中波长为0.52μm的黄光增透，至少要在镜面上涂厚度为多大的增透膜？（假定做这种膜的材料的折射率为1.3）