Mirrors can be produced as broadband mirrors for the whole visible range or as wavelength-selective mirrors reflecting only one laser wavelength or a small range of wavelenghts for a LED light source.
Whereas broadband mirrors will reflect typically only 97% - 98% in the whole VIS range, special mirrors with a reflectivity higher than 99% will be possible for a selected wavelength or a small range of wavelenghts.
Such selective mirrors can be calculated for different wavelengths, e.g. RGB.
Typically such mirrors are used under AOI 45°, but also other angles of incidence can be realized.
The diagram shows measured spectral reflectivity curves for a blue reflecting mirror unter AOI 40° - 50° measured in p-polarization. The reflectivity exceeds > 99% for AOI 45° and > 98,5% for AOI from 40° - 50°.
Hint: For all selective mirrors under non-perpendicular angles of incidence polarization effects have to be taken into account.