What does the film in PVC film mean?
The film can be a transparent solid, a liquid or a thin layer of gas sandwiched between two pieces of glass. The incident light is reflected by the upper surface of the film to obtain the first light, the refracted light is reflected by the lower surface of the film, and then refracted by the upper surface to obtain the second light. The two lights are on the same side of the film and are separated by the same incident vibration. , Is coherent light, which belongs to sub-amplitude interference.