Highly reflective mirror reflectivity spectra

The simple free electron model (the Drude model) developed in Section 4.4 for metals successfully explains some general properties, such as the filter action for UV radiation and their high reflectivity in the visible. However, in spite of the fact that metals are generally good mirrors, we perceive visually that gold has a yellowish color and copper has a reddish aspect, while silver does not present any particular color that is it has a similarly high reflectivity across the whole visible spectrum. In order to account for some of these spectral differences, we have to discuss the nature of interband transitions in metals. 

The instrument most commonly used to resolve the Brillouin spectrum is the Fabry-Perot interferometer. This device consists of a pair of highly reflective, optically polished mirrors. The transmission function for a plane parallel Fabry-Perot interferometer is ... 

First, the sensitivity of CRDS stems in part from the enormous number of passes each laser pulse makes between the high-reflectivity mirrors, giving effective path lengths of up to a few kilometres, far higher than for conventional multipass arrangements. And by measuring the ring-down decay rate rather than absolute intensity of the laser pulse, pulse-to-pulse variations in laser output are removed from the final spectrum. These two aspects allow the detection of absorptions smaller than 10 per pass. 

Fig. 7. The reflectance accessory according to Strong is a tool to measure absolute values from high-reflectance mirrors. Results are obtained in that can be easily converted into percentage reflectivity. The spectrum shows the reflectivity of a laser mirror for a HeNe laser (12).

Theoretical consideration of the IR spectroscopy of monolayers adsorbed on a metal surface showed that the reflection-absorption spectrum is measured most efficiently at high angles of incidence, and that only parallel component of incident light gives measurable absorption species (23). Figure 4 presents a schematic description of a monomolecular film on a mirror, with the incident light and direction of the polarization. Figure 5 presents, in detail, an alkyl thiol molecule on a metal surface. Note the direction of the different transition dipoles. Thus, while both the... 

This approach first proposed by Solar Systems in Australia employs a dish concern trator that reflects sunlight onto a focal point (see Fig. 6). At the focal point is a spectral splitter (heat mirror) that reflects infrared solar radiation and transmits the visible sunlight to high-efficiency solar cells behind the spectral splitter. Figure 7 schematically shows the transmission across the solar spectrum wavelengths. 

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