Optical properties of RICH detectors

In this review article11 d talk at RICH 2013, December 4, Kamakura, Japan. scuss the optical components in RICH detectors. In particular we mention transmission and refraction index in gases, liquids, solids, optical glues, matching gels and aerogel. We mention a few examples of mirror reflectivity in UV and visible region. We also discuss radiation damage, radio-luminescence, yellowing from light exposure, optical distortions in materials, and scintillation.