How are periscopes used in real life?

Answer 1

There are many types of periscopes used in different applications. A periscope is useful anywhere where you cannot or do not want to stick you head out to see something.

Most commonly periscopes are associated with submarines, where they are used to look above the water without having the boat surface. This lets the sailors see the situation while being safely hidden underwater.

Periscopes are also used in tanks to see without sticking out of the hatch. This keeps the crew from getting shot when they are checking out the battlefield. There are also trench periscopes used for the same reason. Also, fortifications such as bunkers can have periscopes to see without going outside.

Police sometimes use periscopes (although cameras are more common now) to look around corners.

There are even periscope peepholes that were used in doors, which are a periscope mounted on the door sideways. The idea was that an attacker might ring the doorbell and shoot under the peephole when hearing someone walk up to the door. Having the eyepiece off to the side would keep the person inside out of the line of fire.