In general, a digital night vision device consists of an objective lens, a light-sensitive sensor, blocks of electronic image processing and a control, a display and an eye piece.
The power supply of digital night vision devices is provided by replaceable power elements: rechargeable batteries of the same size or integrated rechargeable batteries. Devices can be equipped with a socket for obtaining power from external sources (e.g. car power grid, compact external rechargeable batteries).
For work in low-light conditions, digital night vision devices are often equipped with integrated infrared illuminators based on laser diode or LED. For increased usability digital night vision devices can include a remote-control system with major functions – in this case the user can control the device with the help of remote control (RC).
Digital devices can be equipped with rails for mounting on weapons.
As in any optic observation device, the objective lens is meant for projecting images onto the surface of the sensor, which in turn transforms reflections from the light of the object into an electric signal.
As a light-sensitive element, digital night vision devices utilize CCD or CMOS sensors.
In contrast to night vision devices based on image intensifier tubes (analogue), digital night vision devices allow a larger quantity of user adjustments and functions to be implemented. For example, brightness adjustment, image contrast, image color selection, additional information in the field of view (current time, battery charge indication, icons of activated modes etc.), additional digital zoom, “Picture in Picture” function (shows, in a separate small window, an additional image of the whole object or its separate part including a magnified image) and temporary display deactivation (for energy-saving purposes and for masking an observer at the expense of absence of illumination from the operating display).
For saving images of observed objects, digital night vision devices may incorporate video recorders that allow photos and videos to be made.
In digital devices it is easy to implement such functions as wireless connection (e.g. Wi-Fi) data transmission (photo video) to external receivers, the integration of laser rangefinders (data from the range finder can be introduced into the field of view) and GPS-sensors (the ability to establish the co-ordinates of the observed object).
One advantage of digital night vision devices is the ability to work in daylight conditions without fear of flashes of light or intensive light sources which may damage night vision devices based on the image intensifier tube.
The reticle in digital riflescopes is as a rule is also digital, which means that the image of the reticle during the video signal processing is overlaid on the image on the screen and moved electronically, avoiding the necessity of mechanical parts for making ballistic corrections. These mechanical parts are often used in analogue night vision and daylight riflescopes and demand high precision during the manufacturing and assembling process.
Additionally, it avoids typical optic or night vision riflescope effects such as parallax, due to the fact that the observed image and the image of the reticle are located in the same plane – in the plane of display.
Digital riflescopes can keep a large quantity of reticles of different configurations and colors in its memory, providing the possibility of quick and easy “one shot zeroing” or “freeze zeroing”, the function of automatic ballistic reticle corrections in the course of alternating shooting distance, saving zeroing co-ordinates for several weapons, indicating weapon side incline or elevation angle, etc.
The main parameters of digital night vision devices are:
- Angle of field of view
- Eye relief
- Power of the Infrared Illuminator
- Detection and recognition distance