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Reflectivity is the square of the magnitude of the Fresnel reflection coefficient, [4] which is the ratio of the reflected to incident electric field; [5] as such the reflection coefficient can be expressed as a complex number as determined by the Fresnel equations for a single layer, whereas the reflectance is always a positive real number.
The behavior of the k(λ) spectrum of ITO in the near-infrared (NIR) and infrared (IR) wavelength ranges resembles that of a metal: non-zero in the NIR range of 750–1000 nm (difficult to discern in the graphics since its values are very small) and reaching a maximum value in the IR range (λ > 1000 nm).
The plane of incidence is defined by the incoming radiation's propagation vector and the normal vector of the surface. There are two sets of Fresnel coefficients for two different linear polarization components of the incident wave.
Spectral reflectance curves for aluminum (Al), silver (Ag), and gold (Au) metal mirrors Alkali-metal coloration: rubidium (silvery) versus caesium (golden) The reflectivity of aluminium (Al), silver (Ag), and gold (Au) is shown in the graph to the right. The human eye sees electromagnetic radiation with a wavelength near 600 nm as yellow.
Such losses become particularly significant, for example, in metals at short (e.g. visible) wavelengths, and must be included in any description of the refractive index. Refraction, critical angle and total internal reflection of light at the interface between two media.
The refractive index, , can be seen as the factor by which the speed and the wavelength of the radiation are reduced with respect to their vacuum values: the speed of light in a medium is v = c/n, and similarly the wavelength in that medium is λ = λ 0 /n, where λ 0 is the wavelength of that light in vacuum.
The metal used determines the reflection characteristics of the mirror; aluminium is the cheapest and most common coating, and yields a reflectivity of around 88%-92% over the visible spectrum. More expensive is silver , which has a reflectivity of 95%-99% even into the far infrared , but suffers from decreasing reflectivity (<90%) in the blue ...
In telecommunications and transmission line theory, the reflection coefficient is the ratio of the complex amplitude of the reflected wave to that of the incident wave. The voltage and current at any point along a transmission line can always be resolved into forward and reflected traveling waves given a specified reference impedance Z 0.