A periscope is an optical instrument that allows one to see around corners or over obstacles. It consists of a tube with mirrors at each end, one of which is semi-transparent. Light enters the periscope through the objective lens and is reflected by the first mirror to the second mirror, which then reflects it to the eyepiece. The observer looks through the eyepiece and sees an image of the scene in front of the objective lens, as if they were looking directly at it. Periscopes are used in a variety of applications, including military, marine, and industrial settings.
Periscopes have been used for centuries, with the first known example dating back to the 16th century. They have played an important role in military history, allowing soldiers to observe enemy positions without exposing themselves to fire. Periscopes are also used in marine applications, such as submarines and diving bells, to allow the occupants to see above the water’s surface. In industrial settings, periscopes are used to inspect machinery and other objects that are difficult to see directly.
