I wondered how a material (maybe for example a glass window) must be made to provide none or very few reflections. And while I think about it I don't really know which interaction is behind reflection. I think it must be rayleigh or thomson scattering? Compton scattering demands too high energy?!

There is also the question Why does a glass window reflect white objects white from an atomic scatterers’ viewpoint? but though it is very related it is more about the color/wavelength reflected, not the process in general.


The classic way to minimize light loss by reflection off the surface of a piece of glass (usually a lens in binoculars or a camera) is by applying a very thin layer of another type of transparent material that has an index of refraction slightly less than that of the piece of glass. The reflections that do occur at the air-coating interface and at the coating-glass interface are smaller overall than for the case when the coating is absent.

This effect can be enhanced if the coating thickness is carefully controlled to equal one-quarter of a wavelength of the light passing through it, in which case the reflection off the air-coating interface and the coating-glass interface will be out of phase and thereby cancel each other out.

There are other ways to do this with special transparent coatings, but these two are the simplest and most common.


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