Types of Night Vision Technology

What types of night vision technology are there?

The most common night vision technologies are image intensifiers, thermal imaging devices, and so-called fusion devices. Image intensifiers use and amplify available ambient light—such as moonlight or starlight—to produce clear images. Thermal imaging devices, on the other hand, detect the heat emitted by people or objects. Fusion devices combine both technologies, delivering highly contrasted images and combining the advantages of thermal imaging and image intensification.

Image Intensifier

An image intensifier, or night vision device, operates based on an electro-optical principle. Available ambient light is captured by a photocathode and converted into electrons. These electrons are then accelerated and amplified within the tube under high voltage before being directed onto a phosphor screen, which makes the intensified image visible.

Early night vision devices of so-called Generation 0 were pure image converters that required a strong infrared light source, as their sensitivity to ambient light was very limited. Modern image intensifiers, however, offer significantly improved performance: they provide much higher image resolution and enable three-dimensional spatial vision, which is especially advantageous in complex tactical situations.

Nevertheless, even modern image intensifiers still require a certain minimum level of ambient light—such as moonlight or starlight—to function effectively. If this residual light is insufficient, an additional infrared light source can be used. However, this may also be detected by opposing forces equipped with night vision technology and used to locate the user.

Thermal Imaging Technology

Thermal imaging devices operate on a completely different principle than image intensifiers. They detect the heat radiation (infrared radiation) emitted by objects or living beings and convert it into a visible image. A special germanium lens is typically used, as this material effectively transmits infrared radiation. The radiation is captured by a sensor, processed electronically, and then displayed on a screen.

A key advantage of this design is that the individual components—lens, sensor, and display—do not need to be aligned on a single optical axis, as is the case with image intensifiers. This allows for a more flexible, compact, and space-efficient construction.

Unlike image intensifiers, thermal imaging devices do not require any ambient light. They function even in complete darkness and can also see through smoke or fog. However, their performance can be limited by heavy rain, snowfall, or glass surfaces, as these materials can block or reflect infrared radiation.

Since the image is generated electronically on a display, thermal imaging devices do not provide true three-dimensional vision, but rather a flat, two-dimensional representation of the observed scene.

Fusion Devices

Fusion devices combine the advantages of image intensifiers and thermal imaging technology within a single system. In handheld or helmet-mounted devices, they typically operate using an overlay principle: the analog image from the image intensifier is preserved, while the thermal image is superimposed via a display or transparent projection. This allows the user to see structural details (image intensification) and thermal signatures (thermal imaging) simultaneously.

Larger systems, such as those mounted on vehicles or weapon platforms, often use digital fusion. In this case, both image sources are electronically combined and displayed as a single digital image. For portable devices, this approach is still technically limited, as the image intensifier output remains analog and cannot yet be seamlessly integrated into a fully digital process without loss.

Another advantage of fusion technology is the ability to overlay additional information. Since a display is used, external images, videos, symbols, or text—such as tactical data or navigation aids—can be integrated directly into the field of view.

Fusion devices are available either as fully integrated systems or as retrofit solutions (“clip-on”), which can be mounted onto existing image intensifiers for flexible upgrades.