periskop

A periskop is an optical instrument that enables an observer to see from a hidden or protected position. It channels light from an external scene through a tube using mirrors or prisms, so the viewer can observe objects above water, behind cover, or around obstacles without exposing themselves.

Most periskop devices use two mirrors set at 45 degrees to reflect light along the tube. Additional mirrors or prisms can provide vertical offset, longer reach, or wider fields of view. Image-erecting periskop preserve the upright orientation of the scene, while simple configurations may invert the image. Modern designs may employ relay optics or cameras to transmit the image to a separate eyepiece or display.

Periskop designs have been widely associated with submarines, where observers can monitor above the surface while the hull remains submerged. The concept was later adopted for armored vehicles and ships, and for other applications requiring observation from a protected position.

Contemporary periskop systems often integrate electronic components. Electronic or optronic periskops use cameras, light amplification, infrared sensing, and digital displays, sometimes with helmet-mounted or remote viewing. Fiber-optic variants transmit the image through optical cables, enabling longer reach and improved survivability in military environments.

Etymology: The word periskop derives from Greek peri, around, and skopein, to look.