How Night Vision Works

When you hear the term night vision, what comes to mind? Is it watching a thriller movie with night vision goggles or playing games in the dark? While it entails that, it encompasses so much more. Whether by physical means or technology, night vision is the capacity to see in low-light environments. Though established in the 1930s by the German military, night vision technology wasn’t popular till the 1950s.

Today, it’s incorporated in soldier or airman’s gear as an important tool since it allows for easy and safe movement in the dark, smoke, or fog during the day. You can go night fishing, hunting, camping, and hiking after dark with night vision devices. While these devices were mainly built for special operations, they’re becoming consumer goods. We’ve defined night vision and its uses; let’s discuss how it works. For better understanding, let’s get acquainted with some terminologies in night vision.

Common Night Vision Terminology 

• Photocathode: This is a negatively charged electrode that emits electrons when illuminated, producing electric currents.

• Anode: A positively charged electrode that permits the flow of electrons in a system.

• Sensitivity: This explains the amount of charge that can be measured and detected.

• Phosphor screen: This emits photons when accelerated electrons hit the material or screen, producing a visible visible-light image.

• MCP: This is a micro-channel plate that multiplies photoelectrons.

• Gain: This is the relative proportion of visible light emitted to the quantity of infra-red input. It’s also the extent to which signals are amplified.

• Active devices: These infrared imaging systems focus infrared light on a scene.

• Passive devices: Compared to active devices, these systems work at longer infrared wavelengths.

• Noise: This is the sound produced as a result of signal amplification on the phosphor screen. Noise deform and conceal images.

Now that we’re familiar with the terminology used in night vision technology, how does it work? This depends on the technologies used by night vision products. This equipment works by image enhancement and thermal imaging.

Image Enhancement

In image enhancement technology, small amounts of light are captured by optical lenses and electronic vacuum, reflecting on objects. The infrared and visible light is amplified by an image intensifier tube. Within the tube’s interior is a photosensitive compound that converts a single electron into thousands through the aid of a micro-channel plate (MCP).

Steps involved in image enhancement

• The objective lens, which is the device’s focal lens, collects low light and infra-red light. This light is mainly composed of photons.

• The light is transmitted to an image-intensifier tube fueled by two minute “AA” batteries.

• At the anterior end of the tube is a photocathode that changes photons into electrons.

• The newly formed electrons travel across the microchannel plate, the next part after the objective lens. The microchannel plate is disclike, having many small holes for amplification of electrons and signals. MCP is coated with electrodes on both sides. When electrons flow through the plate, they lead to the discharge of numerous electrons.

• The electrons move to the posterior end of the tube and collide with the phosphor-coated screen. When a collision occurs, the phosphors get activated, emitting photons that produce a bright green image in real-time. The image formed is usually of a more brilliant hue than the one captured by the objective lens.

• With an ocular lens, you can view and enlarge the green phosphor image. You can decide to view it through a monitor.

Thermal Imaging

This technology employs the use of heat to create images of objects. Here, some infrared light is collected and released as heat rather than a reflection of light on objects.

Steps involved in thermal imaging

• A modified lens combines and focuses light discharged from materials.

• An infrared detector screens the focused light based on temperature pattern, known as a thermogram. Some thermal imaging devices use a microbolometer in reading temperature differences between objects and surrounding mediums.

• Electrical impulses are formed from the conversion of temperature patterns.

• These electrical impulses pass through a circuit board, a signal processing system that converts information derived from the thermogram to a data display.

• The circuit board transfers information to the display forming colors according to the magnitude of infrared radiation. Images are formed from the fusion of impulses and detector elements.

Applications of Night Vision

The application of night vision technology can be seen in scopes, goggles, and video cameras. Whether handheld or attached to rifles, scopes enable you to obtain a good view of far objects. Goggles are often used when navigating within buildings in the dark. Video cameras utilize night vision technology when shooting videos in dark or low-light situations.

Other applications of night vision include the following:

• Military

• Security

• Hunting

• Entertainment 

• Detection of hidden object

Night vision technology is crucial in our modern-day world. From surveillance to armed operations and hunting, night vision devices are used in almost all sectors. Are you camping or game hunting? These devices will come in handy. Ensure you make the right pick. Do you find this article helpful? Let us know your thoughts in the comments box.