# Periscope

## What is a Periscope

A periscope is an optical instrument for viewing objects that are above the level of direct sight or otherwise in a obstructed field of vision. It prevents direct line of sight and was used in World War 1 and in submarines

## Early Years...

The periscope all started in the 1430s, when Johannes Gutenberg who was known for his contribution to printing technology, marketed a kind of periscope. He enabled pilgrims to see over the heads of the crowd at various religious festivals. Years later, he later saw military applications for his new invention.

## Military Use

In 1854, Hippolyte Marié-Davy invented the first official naval periscope, consisting of a vertical tube with two small mirrors fixed at each end at 45°. It was mostly being used in submarines. The device was later perfected in World War 1. It let soldiers use periscopes on their rifles to allow soldiers to see over the tops of trenches, avoiding exposure to enemy fire. During World War 2, artillery observers and officers used specific periscope binoculars with different mountings. This allowed them to estimate the distance to a target.

## Analyzing A Periscope

Understanding how a periscope works is fairly easy to understand. There are basic periscopes and then more complex ones. The main components of a periscope is a vertical rectangular tube and two mirrors.

## How A Basic Periscope Works

A simple periscope is just a long tube with a mirror at each end. The mirrors are fixed at each end of the tube at an angle of exactly 45 degrees so that they will be facing each other. Within the periscope, the light ray will hit the top mirror at 45 degrees and reflects away at the same angle. The light ray will then bounce to the bottom mirror. When the reflected light hits the second mirror, it is reflected again at 45 degrees and then comes right to your eye.

## The Law Of Reflection

A periscope works on the laws of reflection. As we can see, there are two plane mirrors being used in this simple periscope. As the light ray hits the first mirror at 45 degrees it will then reflect it at 45 degrees which shows us how the Law Of Reflection is taking place. Making a periscope like this will require accurate measurements and the mirrors would need to be precisely fitted because the ray that hits the mirror or normal (incident ray) will need to reflect at the same angle (reflected angle).

## How Complex Periscopes Work

More complex periscopes use prisms or advanced fiber optics instead of mirrors. These periscopes provide magnification and mainly the ones that are operated on submarines. It works by the incoming light which is known as incident ray hitting the back surface of the first prism at an angle which is greater than the critical angle. When the light rays pass from one one medium to another, it is partially reflected and refracted. And since the angle of incidence is greater than the critical angle, light is being reflected.

## Comparing The Two Periscopes

Most reliable periscopes work through prisms instead of mirrors because prisms are more durable and last longer. Mirrors are also easily damaged which is why mirror periscopes are not used in submarines. Salt water can easily damage the aluminum or silver coating of mirror. And this causes the vision to be blurred which is why prisms are the right choice. However, if you need a easy and cheap periscope, the mirror one would be the right fit.

## How Has It Enhanced Society

Periscopes are essential to our society because it is being used to protect our navies and army. If they were not used in the First World War, large amount of troops and soldiers would have had to risk their lives and possibly die. This object saved us many lives. Periscopes are even used today on ships to prevent accidents. Submarines would also have a lot of trouble because they would not be able to see what is above the water. It helped submarines navigate around the water easier. Since submarines can navigate easier, this allows for more discovery in unknown species.
How To Make a Periscope | Homemade Periscope DIY

## To Conclude

Ultimately, the society has benefited from using the periscopes from the past and present. Without periscopes, many soldiers would have died in the war, there wouldn't be safe navigation for submarines, ships and finally helped humans detect illness or disease in the body. The periscope would be a great example connected to optics. Using light through mirrors and prisms that also follow the Laws Of Reflection.