Diaphragm (optics) the lens. The centre of the diaphragm's aperture coincides with the optical axis of the lens system. Most modern cameras use a type of adjustable diaphragm known as an iris diaphragm, and often referred to simply as an iris. See the articles on aperture and f-number for the photographic effect and system of quantification of varying the opening in the diaphragm. A natural optical system that has a diaphragm and an aperture is the human eye. The iris is the diaphragm, and the opening in the iris of the eye (the pupil) is the aperture. An analogous dev in a
Sigurd Snake-in-the-Eye Sigurd Snake-in-the-Eye Sigurd Snake-in-the-eye (Old Norse: Sigurðr ormr í auga) was a Viking warrior in the middle of the 9th Century. He was supposedly one of the sons of the legendary Viking Ragnar Lothbrok. "Snake-in-the-eye" as part of Sigurd's name denoted a physical characteristic. He was born with a mark in his eye, described as the image of the Ouroboros (a snake biting its own tail). The snake mark had been prophesied by his mother Aslaug, the daughter of the Valkyrie Brynhildr. As a boy, Sigurd was close to his father and accompanied Ragnar on a hazardous expedition through Rus'