It was the curved shape of the lens that led to its name being borrowed, in the late 17th century, from the Latin name of the lentil plant, lens culinaris. In French, another word for lens is objectif ...

Lenses are used to bend and focus light. Normal lenses rely on their curved shape to achieve this effect, but physicists have made a flat lens of only three atoms thick which relies on quantum effects ...

It’s often called the optic that best approximates human vision, but approximation is relative. An Object Lesson. But the concept of “normal vision,” let alone the 50-mm lens’s ability to reproduce it ...