Types of Night Vision
Night Vision Optics utilize both the visible light and infrared lights, as shown in the electromagnetic spectrum in the figure above, to gain night vision images of the surroundings. Infrared light are invisible to naked eyes, thus suited to be used in various real-life applications that require both observation and concealment.
This technology emphasize on the usage of an active infrared light source to illuminate the surroundings and an IR-sensitive camera to capture the images. The resulting images captured are of high monochromatic resolution due to the high infrared light intensity emitted. This technology is commonly applied in security systems.
Most of the night vision oculars available in market incorporate image intensifier tubes as its primary night vision system. This system focuses on capturing enough visible light and near-infrared light sources from surroundings (eg. moon, stars, etc.). The photons gained are processed into images via image intensifier tube, almost identical to the system of cathode ray tube (CRT). This technology is ever popular in various night vision applications.
Thermal Vision technology is considered to be cream of the crop among night vision technologies. Thermal vision imaging operates via infrared sensing whereby it detects the infrared emitted by surroundings. Generally, living things emit more heat and infrared wave as compared to still objects like trees and buildings. This will in turn lead to thermal images being detected through temperature difference. On top of that, thermal vision imaging do not require illumination source and capable of producing image in almost all conditions (eg. moonless night, rain, fog and smoke).
Night Vision Technology
Night vision devices have progressively advanced through the years. These technological advancements are classified as generations, where each generation vary in in terms of design, technology and performance. Below listed are the night vision generations that have been developed through these years:-
Night Vision Devices (NVDs) were first utilized by the United States Armed Forces during the World War II. These NVDs employ active Infrared (IR) Illuminator technology by promoting electron acceleration. This setup would project near-infrared beams invisible to the naked eye and would in turn reflect off surrounding objects, creating illumination in low-light conditions. However, the devices have considerably short life-span and images produced were great distorted due to excessive IR light reflected upon.
Gen 1 NVDs take improvements from the previous Gen 0 NVDs by implying passive IR technology to its devices. This technology uses ambient light from the moon and stars to illuminate the surroundings instead of an infrared light source. Gen 1 NVDs are capable of amplifying light up till 1000x with maximum viewing range up to 75 yards depending on the night. Nonetheless, Gen 1 NVDs are capable of lasting up to 1500 hours, a remarkable improvement over Gen 0 NVDs. Gen 1+ NVDs are classified as the more advanced version of the Gen 1 night vision scopes with slight improvement in terms of build quality, lens grade and control design. In spite of that, these devices utilizes the same technology as Gen 1 night vision devices, thus the benchmark performance for Gen 1+ devices is only slightly higher than those of Gen 1 devices.
The improved Gen 2 NVDs are equipped with upgraded image intensifier tubes which provide more image clarity and brightness than its predecessor. Nevertheless, these NVDs are capable of providing optimum performance of up 200 yard area, even in extremely low-light conditions (eg. moonless and cloudy nights). Gen 2 NVDs have approximately 5000 hours life expectancy so expect your Gen 2 NVDs to give you a run for what it's worth. Gen 2 night vision tubes have different variations as well according to its specifications. Among the variations available are standard, military specifications, custom grade and high performance tubes.
Gen 3 NVDs are the epitome of night vision devices and only available to military units. Its performance is generally a cut above the rest as its equipped gallium arsenide is capable of boosting image resolution, low-light performance significantly. On top of that, autogated Gen 3 NVDs allow for operations in all light conditions without 'blooming' effects (image distortion caused by light). By far, Gen 3 NVDs with its state-of-art technologies are capable of lasting for up till 10,000 hours. Gen 3 night vision optics are also classified according to specifications, such as standard and autogated night vision scopes. Autogated night vision scopes are capable of delivering optimum performance at all light conditions and are currently utilized by US Military Forces. These solid NVDs are definitely built to last.