Technology has come a long way in recent years, and objects that we could not see at night underwater until recently have become visible thanks to the same technology. In general, it looks like this, optical sights, binoculars, goggles, and other optical devices have night vision lenses so that these devices "see" the target in complete darkness. It is also dark underwater, but conventional optical instruments do not allow us to see at a distance in this environment. So does underwater night vision work, and how does it work? When buying an expensive night vision device, you should first understand if you need the purchase and how the device works. It is not enough to know that it consists of a lens, a radiation receiver, a signal display device, and an amplifier. In general, the basic principle of operation of night vision devices is based on the work of the electro-optical converter, which uses infrared radiation by amplifying the brightness of the observed object. We get an object visible in the infrared spectrum. To put it simply, it is a particular photoelectronic device that transforms an invisible object into a visible one in total darkness. It is given contrast and brightness with color enhancement. 

How does night vision work? 

A standard night vision device is quite simple in execution, it can have natural light, or infrared illumination converted into a visible spectrum. The human eye does not have enough sensitivity to look at an object in detail in the dark. This problem is corrected by night vision devices, the development and refinement of the model range, which is continuous. These devices are divided into generations, beginning with the zero generation, where a multi-alkaline photocathode and optical elements were used.  The second generation of the devices was enhanced by a more powerful photocathode, a microchannel amplifier, and divided into two lines of research - inverter and biplanar devices—the third generation biplanar electron-optical devices with semiconductor photocathode. Hence, the logic of optical night vision devices is based on capturing infrared light coming from warm bodies. And then it's simple: the light is amplified and transmitted to the screen. If you use your imagination, it looks straightforward.

Reflected light from the object of observation hits the input lens, which collects on the lens and focuses the image on the photocathode. The transducer amplifies the incoming light through the lens and transmits the images to the screen. This is the passive mode of operation when the existing light flux is amplified. When the visibility is zero, and there is nothing to strengthen in the passive mode, the device becomes "blind." In this case, an infrared illuminator is built-in or separately mounted in most night vision devices, which solves this problem.  This is an additional source of light, giving the possibility to work in absolute darkness. Such a device is considered to be active. In addition, the market now offers night vision devices developed based on an electro-optical converter and a digital matrix in the fourth generation, remaining unchanged in the principle of operation - amplification from weak light sources. The devices in different generations are pretty good, although they differ in some features and price. 

It should be noted that today, devices that do not have an electron-optical converter are popular. These are thermal imagers and digital devices. Thermal imagers capture thermal radiation in smoke and fog and, in absolute darkness, can "see" animals in bushes, grass, and reeds. Unfortunately, the work of these devices is limited by the temperature of the air - not above thirty-five degrees of heat.  "Digital" converts the light of a light-sensitive matrix into a digital signal.

Does the night vision device work underwater?

The answer to this question is unequivocal - yes, it does. Night vision devices are specially created for this purpose. Some night vision scopes are used underwater for military activities, search operations, diving, and sea hunting. Such equipment is waterproof and can be used for many purposes. True, without the nuances, can not do without. Of all the aspects of difficult moments, the most important is the medium of action. In everyday life, it is air, which we do not consider as something for the propagation of light waves, but we associate with it in our daily worldview: water droplets, dust, snow, smoke, water vapor, and others.

Because of a specific density of air and its saturation, less light enters the night vision lens than in a perfect vacuum.   And what does the propagation of light waves in water look like? After all, water is more densely structured than air. It is a perfect absorber of radiation, from light to heat. And seawater is also saturated with salts, making it difficult for light waves to pass through. However, this is not the only factor that affects the performance of the night vision device underwater. We can add the concept of distance, waves, and sea currents here. After all, water in the natural environment is not stable. It moves and has waves, eddies, and currents, which distorts the reflection from the infrared light used in tandem with the night vision device. The pulsed laser works a little better underwater, which gives a better image. 

Technology in an underwater night vision scope 

The desire to see well underwater at night has always been inherent to the underwater hunter. It has made it easy to navigate and avoid danger. After all, all we see is light that is reflected from objects.  Many night vision devices are specially designed for this purpose. Clear images underwater have been achieved by equipping night vision devices with modern electro-optical converters. Such equipment is waterproof and is used by divers and underwater hunters. You should look at night vision goggles for scuba diving, which will solve all your problems and make diving underwater easier.

The waterproof qualities of a night vision device underwater

The right equipment is half the success of the event. Recently they have started to use thermal imaging cameras for underwater work, which replace night vision devices and use digital image intensification technology. The advantage of cameras is their compactness, and the optics of these devices give an image with digital enhancement. Here the image is immediately converted into a digital signal and, with magnification and sharpening, is transmitted to the display screen for viewing. They are entirely waterproof. These night-vision goggles make diving, scuba diving, training, and education much safer and more accessible. The waterproof qualities of the night vision goggles have proven themselves in adverse weather conditions. They are water-resistant and can be freely used underwater without fear of damage or weathering. When selecting diving equipment, consider that the equipment must be rated for a specific dive depth.