Information on a compact disc is recorded as binaric "pits" and "lands". Information can be read perpendicularly from downside of the disc by a laser with?₀ = 780 nm and that goes through a plastic layer with n = 1.55

1. How the reading happens i.e. how is the information extracted from the edge of the pit and theland vie the reflected wave?
2. What is the required height difference t for the pit and the land in order to make reading of the information possible?

Reflecting Reflecting "pir "land Plastic n = 155 Laser beum