Pressurization

pressurization

Injecting a gas (usually nitrogen) with a very low moisture content into the body of an optical instrument to create a positive internal pressure. This prevents the entrance of moisture, which could cause fogging of the optics. While the nitrogen has the same index of refraction as the air it replaces, the fact that it is under some level of pressure may cause an index change that must be compensated for.

convex

Convex is an adjective used to describe a surface or shape that curves outward, bulges, or has a rounded and outwardly extending appearance. In the context of geometry or optics, a convex shape is one that is curved or sloped outward, creating a surface that is raised or protruding. For example: Convex lens: In optics, a convex lens is thicker at the center than at the edges, causing light rays passing through it to converge. Convex lenses are commonly used in magnifying glasses, eyeglasses...