The following poem is correct about the phenomenon of light, er, sitting in a well and watching the extremely weak light refraction seen by the sky. It must be the sea.

"Looking at the sky from the well, you can see very little" is the phenomenon that light travels along a straight line, so option A is incorrect;

The infrared money detector uses the penetrating ability of infrared rays, so option B is wrong;

Incident angle and reflection angle refer to the angle between incident light or reflected light and normal, not the angle between incident light and mirror, so option C is incorrect;

When obliquely incident from one medium to another, the opposite direction of light propagation will change, that is, refraction;

So choose D.