The periscope is an optical device. It is a telescope which has a system of mirrors, prisms and lenses. Its purpose is to carry out observation from a variety of shelters, which include shelters, armored towers, tanks, submarines.
Historical roots
The periscope has been conducting its biography since the 1430s, when the inventor Johannes Gutenberg came up with a device that made it possible to observe spectacles at fairs in the city of Aachen (Germany) over the heads of a crowd of people.
The periscope and its structure were described by the scientist Jan Hevelius in his treatises in 1647. He intended to use it in the study and description of the lunar surface. He was also the first to use them for military purposes.
First periscopes
The first real and efficient periscope was patented in 1845 by the American inventor Sarah Mater. She managed to seriously improve this device and bring it to practical use in the armed forces. So, during the American Civil War, soldiers attached periscopes to their guns for secretive and safe shooting.
The French inventor and scientist Davy in 1854 adapted the periscope to the naval forces. His device consisted of two mirrors deployed at an angle of 45 degrees, which were placed in the pipe. And the first periscope used in a submarine was invented by the American Doughty during the American Civil War of 1861-1865.
During the First World War, soldiers of the warring parties also used periscopes of various designs for firing from shelters.
During the Second World War, these devices were widely used on the battlefield. In addition to submarines, they were used to observe the enemy from shelters and dugouts, as well as on tanks.
Almost from the moment submarines appeared, periscopes on them have been used for monitoring when the submarine is in an underwater position. This happens at the so-called “periscope depth”.
They are designed to clarify the navigational situation on the sea surface and to detect aircraft. When the submarine begins to sink, the periscope tube is drawn into the hull of the submarine.
Design
The classical periscope is a design of three separately located devices and parts:
- Optical tube.
- Lifting device.
- Cabinets with oil seals.
The most complex constructive mechanism is the optical system. These are two astronomical pipes combined with each other by lenses. They are equipped with mirror prisms of total internal reflection.
The submarines have for the periscope and additional devices. These include rangefinders, heading angle systems, photo and video cameras, light filters, as well as drying systems.
To establish the distance to the target in the periscope, two types of devices are used - rangefinder grids and micrometers.
The filter is indispensable in the periscope. It is located in front of the eyepiece, divided into three sectors. Each sector represents a specific color glass.
The camera of the device or another, designed to obtain an image, is necessary to establish the facts of hitting targets and recording events on the surface. These devices are installed behind the periscope eyepiece on special brackets.
The periscope tube is hollow, it contains air that contains a certain amount of water vapor. In order to remove moisture settling on the lenses, which condenses on them due to temperature changes, a special drying device is used. This procedure is carried out by quickly sweeping dry air through a pipe. It absorbs accumulated moisture.
In a submarine, the periscope looks like a pipe protruding above the wheelhouse with a “knob” at the end.
Tactics of use
To ensure stealth, the periscope of the submarine is lifted out from under the water with certain periods of time. These intervals depend on weather conditions, speed and range of objects to be observed.
The periscope assists the submarine commander in determining the direction (bearing) from the submarine to the target. Allows you to determine the course angle of the enemy ship, its characteristics (type, speed, weapons, etc.). Gives information about the moment of carrying a torpedo volley.
The dimensions of the periscope protruding from under the water, with its head of the head, should be as small as possible. This is necessary so that the enemy does not fix the location of the submarine.
For submarines, enemy planes pose a very great danger. As a result, during the transitions of submarines considerable attention is paid to the control of the air situation.
However, to carry out such a combined observation, the end part of the periscopes is quite massive, since the optics of anti-aircraft observation are located there.
Therefore, two periscopes are placed on the submarines, namely the commander’s (attack) and anti-aircraft. Using the latter, one can observe not only the air situation, but also the surface of the sea (from the zenith to the horizon).
After the periscope is raised, the air hemisphere is inspected. Observation of the water surface is initially carried out in the bow sector, and then goes on to review the entire horizon.
To ensure secrecy, including from enemy radar, in the intervals between rises of the periscope, the submarine maneuvers at a safe depth.
As a rule, the elevation of the periscope of the submarine above sea level is in the range from 1 to 1.5 meters. This corresponds to the horizon visibility at a range of 21-25 cable (about 4.5 km).
The periscope, as mentioned above, should be located above the surface of the sea as little time as possible. This is especially important for a submarine that starts an attack. Practice says that it takes a little time, about 10 seconds, to determine the distance and other parameters. Such a time interval for the periscope to be on the surface ensures its complete secrecy, so it is impossible to detect it in such a short time.
Footprints on the surface of the sea
When the submarine moves, the periscope leaves a trace and a breaker. It is clearly visible not only in calm, but also with a slight sea swell. The length and nature of the breaker, the size of the track, are directly dependent on the speed of the submarine.
So, at a speed of 5 knots (about 9 km / h), the length of the periscope wake is about 25 m. The foamy wake from it is clearly visible. If the speed of the submarine is 8 knots (about 15 km / h), then the track length is already 40 m, and the breaker is visible at a great distance.
When the submarine moves into the calm, a pronounced white color of the breaker and a voluminous foamy trace appear from the periscope. It remains on the surface even after the device is pulled into the case.
As a result of this, before picking it up, the submarine commander takes measures to slow down the speed of movement. In order to reduce the visibility of the submarine, a streamlined shape is attached to the end part. On the available photos of the periscope, this is easy to notice.
Other disadvantages
The disadvantages of this surveillance device include the following:
- It can not be used in the dark, as well as in conditions of insufficient visibility.
- A periscope, looking out of the water, without significant difficulties can be detected both visually and with the help of radar means of the probable enemy.
- The photos taken by observers of such a periscope are what are the hallmark of finding submarines here.
- With its help it is impossible to determine the distance to the target with the necessary accuracy. This fact reduces the effectiveness of the use of torpedoes on it. Moreover, the periscope detection range leaves much to be desired.
All the above drawbacks have led to the fact that in addition to the periscopes, new, advanced means of observation for submarines have appeared. This is primarily a radar and sonar system.
A periscope is a must-have device on a submarine. The introduction of new devices (radar and sonar) into the technical systems of modern submarines did not reduce its role. They only supplemented its capabilities by making the submarine more “sighted” with poor visibility, in conditions of snow, rain, fog, etc.