Generations of Night Vision Scopes

Night vision scopes have been around for more than forty years, and are characterized by generation. Each substantial change in NVD technology brings with an entirely new generation, from 0-4. If you are looking at a night vision scope that is generally known as a "bargain," then it probably uses Generation-0 or Generation-1 technology, and you may find yourself disappointed if you were expecting a much more sensitive device. Generation-2,3, and 4 are going to be quite expensive to purchase, but, if well cared for can be a lifetime purchase.

Generation-0

The United States Army created the original night-vision system which was powered by active infrared, meaning a projection unit, called an IR illuminator, was attached to the night vision device. The unit then projected a beam of near-infrared light-something akin to a regular flashlight beam-which reflected from objects, bouncing back to the lens of the NVD. These original night-vision systems were used in World War II as well as the Korean War, and also used anodes in conjunction with cathodes to accelerate the electrons. The down side to this particular system lies in the fact that the acceleration of the electrons distorts the image, greatly decreasing the life of the tube. Unfortunately this Generation-0 technology was quickly duplicated by our enemies, which allowed them to use their own NVD's to see the infrared beam projected by the opposing parties own device.

Generation-1

Following the inception of the original Generation-0 night vision scope, passive infrared began to be used, as the move was to get away from the active infrared. The U.S. Army called these Generation-1 NVD's Starlight because they use the ambient light from our moon and stars to supplement the normal levels of infrared found in our environment. Because of this technology, the Generation-1 NVD's did not require a source of projected infrared light, however also do not work very well on cloudy or moonless nights. Because Generation-1 NVD's use the same type of image-intensifier tube technology as the original Generation-0, image distortion and short tube life are still serious problems.

Generation-2

The Generation-2 NVD's ushered in some major improvements regarding the image-intensifier tubes, providing much better resolution and performance and are much more reliable as well. Generation-2 NVD's offer the ability to see in extremely low light conditions, even on a moonless night; the NVD accomplishes this feat through the addition of the micro-channel plate to the image-intensifier tube. The micro-channel plate increases the number of electrons rather than simply accelerating the original one, leaving the images considerably less distorted as well as much brighter.

Generation-3

Our United States military currently uses Generation-3 technology, and though the Generation-3 does not incorporate any new underlying technology, they do have much better resolution and sensitivity due to a photo cathode made from gallium arsenide. Gallium arsenide is much more efficient at converting photons to electrons, and the micro-channel plate on the Generation-3 NVD's is additionally coated with an ion barrier, which offers a substantial increase for the life of the tube.

Generation-4

The Generation-4 night vision devices add a technology known as "filmless and gated," which offers considerable improvements in low and high-level light environments. The Generation-4 NVD removes the ion barrier added to the Generation-3 NVD, which reduces the background noise, and enhances the signal to noise ration; by removing the ion film, more electrons can reach the amplification stage, leaving the images brighter and less distorted. A "gated" power supply system allows the photocathode voltage in the Generation-4 NVD to switch on and off rapidly, enabling the NVD to respond to fluctuating light conditions in a mere instant.