"Generation Designations
Levels of night vision technology are known as generations. Each generation corresponds to a U. S. military specification defining components, performance requirements, and quality parameters. Night vision devices come in three accepted generations of design (Generation 1, 2, and 3). Other designations (Generation 1+, 2+, 3+ and 4) may offer improvements, but do not correspond to official accepted generations. These designations are not specifically defined, and the names are not consistently applied.
Levels of night vision technology are known as generations. Each generation corresponds to a U. S. military specification defining components, performance requirements, and quality parameters. Night vision devices come in three accepted generations of design (Generation 1, 2, and 3). Other designations (Generation 1+, 2+, 3+ and 4) may offer improvements, but do not correspond to official accepted generations. These designations are not specifically defined, and the names are not consistently applied.
Some manufacturers are also touting Generation 4 night vision devices. These have not been officially adopted by the military so the designation has not gained general acceptance. We will discuss this generation briefly below since it is likely that this designation will indeed gain acceptance and official military specifications (mil spec definition).
Generation 1 Night Vision
First Generation night vision devices are the most common and inexpensive consumer models on the market today. These devices have a great range of quality (more so than any other generation). To give a feel for price, Generation 1 monoculars range from about $100-$400. The differences in quality and features are extensive within this price range.
Generation 1 night vision was originally developed by the US military in the Vietnam War. These devices are also called Starlight scopes and were a tremendous improvement upon the Generation 0 devices, mainly through improvements in the photocathode.
Generation 1 devices certainly have their uses although the image distortions (discussed above under Image-intensifier tube), lower light gathering ability, and range in quality can discourage initial buyers from the technology.
Good Generation 1 devices, although significantly lower in light gathering ability than Generation 2 devices, gain tremendously in effectiveness with the standard incorporation of IR Illuminators. These units are often all that is needed for campers and boaters. General nature observation at night might also be comfortable with better models although the image distortions and low light-gathering ability make anything other than general behavior observation difficult.
The best performance is achieved in Generation 1 devices by using fully-coated all-glass optical elements. Units which incorporate plastic (composite) optics are not recommended.
Generation 2 Night Vision
The main design change between Generation 1 and Generation 2 night vision was the addition of the microchannel plate that we discussed above under the image-intensifier. The introduction of the microchannel plate significantly improved the light amplification ability of the devices. Multiplying the number of electrons provided a much brighter image. Forcing the electrons into a linear path as they flow through the microchannels ensures more orderly output and much less distortion in the resulting image. This also allowed there to be less charge in the intensifier tube, since acceleration was not the principle source of light amplification, resulting in increased battery and tube life.
The significant increase in capability of Generation 2 devices comes at a big jump in cost though. Generation 2 monoculars range in price from about $1000-$1500. Although this is a significant jump in price, the image quality, brightness and extended life over Generation 1 products make these a much more sensible investment for serious night vision users.
Generation 3 Night Vision
In Generation 2 designs, the main improvements came with the addition of the microchannel plate, but the photocathode had only minimal improvement. Generation 3 devices were substantially improved by changing to a new photocathode material - gallium arsenide. An ion barrier film was added to increase image-intensifier tube life. This, along with more improvements in the microchannel plate, gave Generation 3 night vision devices much greater light amplification abilities, better resolution and clearer images with less noise.
Once again these newer devices come at another significant jump in cost. In our price comparisons, we see Generation 3 monoculars running about $3,000-$4,000. Although they still benefit from the addition of an IR illuminator, the increased sensitivity of these devices allows them to be operated entirely passively outdoors.
Generation 3 night vision, because of the higher cost, is normally reserved for only the most demanding naturalists, researchers, police, Homeland Security, etc. They are such high tech instruments that both these and Generation 4 night vision devices are restricted in sales and cannot be shipped out of the United States without special permits from the State Department.
Generation 4 Night Vision
Officially there is no accepted (by the military) Generation 4 night vision technology although the term is used/accepted among night vision manufacturers. The designation is widely debated and is referred to as Filmless & Gated image intensifiers by the US military.
The "filmless" terminology refers to the removal of the ion barrier film that was added to the Generation 3 image-intensifiers. This provides a higher signal to noise ratio (less "snow" in the image). The "gated" terminology refers to a gated power supply. This technology makes it possible to operate night vision devices during daylight (if necessary). It also improves the image resolution and minimizes halo from bright light sources. If, for instance, you have a distant house light in view the typical halo around the light is minimized and the overall image resolution is improved.
Once again this all translates into an even sharper view over Generation 3 night vision, even greater ability to see in very dark conditions and another jump in price. Our general price comparison of this technology shows monoculars running about $5,000-$6,000. "
