Sapphire Window for Underwater and Deep-Sea Cameras: Pressure, Salt and Optical Performance
Quick answer: A deep-sea camera port is a pressure boundary before it is an optical component. Single-crystal sapphire is specified because it combines Mohs 9 hardness, mechanical strength sufficient for high pressure differentials, broad UV-to-IR transmission and near-total inertness to seawater — where glass and acrylic ports scratch, craze and [...]