Night vision refers to the technological or biological ability to see in the dark or low-light conditions. Some animals are equipped to see in the dark, but humans don’t have this ability. This makes us wonder, what does night vision look like?
They say eating carrots improves eyesight, but how many carrots do you have to eat so you can see in the dark? There are two combinations of approaches that make night vision possible: the sufficient intensity range and the sufficient spectral range. Eating carrots is not one of them, unfortunately.
The human eye is intended to see during the day and to sleep during the night. The retina, the light-sensitive part, contains cones for perceiving colored light and rods for identifying movements in the dark. Although the eye has six million cones and 120 million rods, it still can’t see in dim-light conditions.
Some animals that tend to live in the dark have different biological structures. They have larger pupils to allow more light to enter. An example is a tarsier that has eyes relatively as big as their body size. Like other night-time creatures, their eyes have more rods than the human eye.
Cats spend their night hunting for prey. Their eyes contain tapetum, a natural mirror that bounces the light back out of sight. It is the reason why their eyes shine when you direct light on them. The function of the tapetum is to reflect the entering light so that the animal has a higher chance to see the objects.
Although the human eye opens wider in low-light conditions, it is not enough to see that much at night. It does not have a tapetum and enough rods. Thanks to technological innovations, though, we can actually equip ourselves to see at night.
Night vision technology was practically invented in Germany in the 1930s. It was utilized in the tanks and infantry during World War II. These devices were called Generation 0 because they used active infrared to enhance the light of an area in dim-lit conditions.
Night vision technology was further maximized in the following decades. In the Vietnam War, US troops used the so-called starlight scopes, which are tubes that worked by image intensification to enhance the available light (usually moonlight and other natural sources) present in the area.
Then, the Generation I technology was invented. It is still being utilized today in affordable night vision devices. Other night vision equipment used by the professionals is now more advanced, and most of them work through image intensification.
Examples of basic equipment with night vision capability are telescopes, binoculars, and some ordinary eyeglasses. They are made of lenses where the light enters through the front and enhance the light in strength. Although they bring the light to a focus, they don’t make the object appear bright.
Night vision equipment that depends on electricity is better. This is because electricity is natural to increase its strength. It is apparent in many electrical devices invented throughout the years. A small flow of electricity gets at one end of the electrical device and yields a more significant flow on the other end. A device or part of a device that has this function is called the amplifier.
The same mechanism happens when it comes to night vision equipment. For example, goggles can boost light. The object in the dark is seen clearly by turning the light into electricity, increasing this electricity, and converting the enhanced electricity back into light. At night, this light appears much brighter so that the users can see it.
How does night vision look like in night vision devices? It can be categorized into three: active illumination, image intensification, and thermal imaging. Each category is described below.
Active illumination works together with imaging intensification with an active cause adjacent to the near infrared or shortwave infrared band. An example of a device with this kind of night vision technology is the low-light camera.
Night glasses and some low-light cameras use image intensification. Image intensification magnifies the volume of photons taken from different natural sources of light, such as moonlight and starlight.
The technology comes as a vacuum tube-based device that can create an image from a meager quantity of photons to make the dark scene appear brighter to the naked eye. The resulting image can be viewed in real time or stored as data for later inspection.
Instead of light, thermal vision technology utilizes temperature to transform dim-lit scenes into a brighter one. It distinguishes the difference in temperature between the foreground and background objects. Some creatures, such as snakes, have this capability of recognizing the raw thermal image through their unique organ that serves as bolometers, a heat detection mechanism.
Thermal cameras use thermal vision technology. Compared to ordinary cameras, they do not require a source of illumination. They actually distinguish thermal radiation. As a result, they can show objects through smoke, rain, and fog.
What does night vision look like in night vision goggles? Everything appears green in such devices. It can be explained by design. The various shades that create the monochrome night vision image are most precisely distinguished when they are in green color. So when the pictures in online games appear green, it means that the scene is in night mode.
Moreover, the human eye is most delicate to light wavelengths close to 555 nanometers; one of them is green. The reflected scene or object appears to be dimmed to save power or battery consumption.
Knowing how night vision works is quite complicated to understand. But how does it look like? Simply put, images seen through night vision come in green color. This is because objects in dim light are more accurate in green, and green conserves power.
Night vision is an important invention in history because it enabled the human race to see in low-light conditions. Although it was first utilized to aid in the war, it is now used in more productive and friendly applications. Police officers use them to monitor areas at night. Some homeowners install security night cameras to monitor their properties during the night and day.