Thin film coating design

Thin film coatings can be deposited to a substrate to modify its reflectance and transmittance properties. The coatings can be a single layer of a material or constructed of multiple layers of materials with contrasting properties. The coatings rely on the optical interference of incident light reflected at the surface and the interfaces between the thin layers.

The optical properties of a surface can be converted to a reflector just with a single-layer coating of the right material. More complex multilayer structures are able to reflect X-rays, EUV radiation and neutrons, and the material and the layer thicknesses are designed for the specific application. In a periodic multilayer with alternating layers of heavy and soft materials, the layer thickness in particular can be tuned for a given wavelength to yield high reflectance at a specific angle of incidence. High reflectance over a wide range of energies/wavelengths and angles of incidence can be obtained with more complex multilayer designs.