Periscopes, in some cases fixed to rifles, served in World War I (1914–1918) to enable soldiers to see over the tops of trenches, thus avoiding exposure to enemy fire (especially from snipers). Morgan Robertson (1861–1915) claimed to have tried to patent the periscope: he described a submarine using a periscope in his fictional works. Sir Howard Grubb perfected the device in World War I.

Simon Lake used periscopes in his submarines in 1902. In 1854, Hippolyte Marié-Davy invented the first naval periscope, consisting of a vertical tube with two small mirrors fixed at each end at 45°. Hevelius saw military applications for his invention. Johannes Hevelius described an early periscope (which he called a 'polemoscope') with lenses in 1647 in his work Selenographia, sive Lunae descriptio. 2.1 Gundlach and Vickers 360-degree periscopes.If the two telescopes have different individual magnification, the difference between them causes an overall magnification or reduction. The overall design of the classical submarine periscope is very simple: two telescopes pointed into each other. More complex periscopes using prisms or advanced fiber optics instead of mirrors and providing magnification operate on submarines and in various fields of science. Military personnel also use periscopes in some gun turrets and in armoured vehicles.

This form of periscope, with the addition of two simple lenses, served for observation purposes in the trenches during World War I. In its simplest form, it consists of an outer case with mirrors at each end set parallel to each other at a 45° angle. The left one uses an erecting prism whereas the right uses an erecting lens and a second image plane.Ī periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position. The two periscopes differ in the way they erect the image.

Kaleidoscope image effect unity