What is a periscope - Info sheet

A periscope is an optical instrument designed to allow an individual to observe objects from a hidden position, typically over an obstacle. The device consists of two plane mirrors which are positioned inside a tube. These mirrors are arranged parallel to one another and are tilted at a precise angle of 45 degrees relative to the incoming light. This specific angle enables the light that emanates from the object being observed to be deflected through a 90-degree turn by each mirror, which then allows the observer's eye to see the reflected image.

Periscopes serve a practical purpose in various situations. For example, they are utilised on double-decker buses to provide drivers with a view of the upper deck, ensuring passenger safety and efficient monitoring of the bus environment. In marine applications, periscopes are an essential tool for submarines, enabling the crew to survey the surface of the water without having to emerge. This capability is crucial for maintaining stealth and safety in naval operations. Overall, periscopes are valuable devices that extend our visual capabilities in situations where direct line-of-sight observation is not possible.