NVIS devices offer unique challenges, both in their design and their operation. To understand some of the challenges, and how to overcome them, it helps to know something about how the devices work.

There are currently two commonly used technologies used for NVIS equipment, although the older of the two is slowly being phased out. This older (traditional?) technology uses optoelectronic image enhancement. An image intensifier is used and works by sensing the small amount of infrared (IR) light being emitted by, or reflecting off, objects. Using a complex lensing system and a special electronic vacuum tube, light is then amplified and presented to a display as an image of the object. In this case, the image is typically green and monochrome.

Most NVIS systems made today use a more recent digital technology that captures the low levels of available light using a digital sensor. In this case, the light captured is converted into a digital signal using (typically) a CMOS device not unlike the camera in a phone, but which is much more sensitive to low levels of light. The signal created in then digitally magnified and enhanced many times. The resultant signal can then be sent to a display for viewing. Unlike devices based on image intensifiers, the output of a digital NVIS device can be provided to displays outside of the device itself, even being sent wirelessly.

The use of digital technology has brought about major changes for both military and civilian use of NVIS devices. Not only are digital systems smaller and lighter, but they are also much more versatile. Not only can digital NVIS devices be viewed directly, but their signal can also be connected to an external viewing screen, transmitted remotely, or stored on USB on SD storage devices. Perhaps equally as important, the images produced can now be full colour, and can be HD resolution or higher. These types of image-enhancing night vision systems are now being extensively used in areas such as wildlife research and photography, in addition to military applications.

However, these improvements in NVIS brings with it new challenges. The older systems based on image intensifiers would “bloom” and overload if large amounts of IR flooded the lens, or if light was shone directly at them. The newer systems are capable of better dampening some of these situations, but when used in an active combat situation such as, say, the cockpit of a combat plane during night operations, every effort must be made to prevent spurious IR emissions from other devices, which could blind the NVIS devices being used.