An Investigation of the Physical Properties of Thin Films used in the Reduction of Surface Reflection

A simple mathematical treatment of reflection from thin films is extended to cover the properties of films likely to be met with in practice. In particular, reflection from multiple films of more than one substance is considered, and the reflection of polarized light from simple films. A photometer used for testing these results is described, and the different types of cryolite films found are enumerated. Evidence is given suggesting that polished or aged cryolite films behave as if they consisted of a lower stratum of cryolite surmounted by a secondary layer of higher refractive index. Some of the properties of this layer are described.