Image Intensifier
An image intensifier (abbreviation: II or I²) is an electro-optical component that can produce an intensified monochrome image on a phosphor screen from a cone of incoming light, intended to intensify the signal beyond what optics and digital sensors are capable of.
In the field of night vision, image intensifier refers to image intensifier tubes which are miniaturized image intensifiers (usually in tubular shape) that form the core component of any night vision device.
Image intensifier tubes are inserted into a housing that otherwise only provides optics, power supply, and protection of the sensitive component. Many formats of image intensifier tubes are designed to be exchangable with limited tooling and know-how, originally intended to allow armies to replace damaged image intensifier tubes by an engineer during deployment.
Generations
Generation 0
Generation 0 was invented in 1929 by a hungarian scientist in the UK. First uses where in World War II by the Germans, later the Soviets and the Americans.
Gen 0 tubes dont have any or only very low gain of a around 10 and thus rely on strong Ir ilumination.
Examples of Gen 0 devices
- Vampir
- M2 & M3 Sniperscope
- PNV57A
Generation 1
Generation 1, developed and patented in the 1960s, improved greatly the Gain to around 1000. This enabled the use of Gen 1 devices under Moonlight conditions without the use of IR ilumination.
Later developments included Gen 1+. There the glass in the body was replaced with ceramic. The gain was further improved.
Some devices used multible tubes in a cascade configuration which leads in strong Gain improvements of up to 100,000.
Examples of Gen 1 devices
- AN/PAS 2 Starlight
- Armasight Spark
- PNV57H
Gen 1 technology is also found in most cheap consumer devices.
Generation 2
The generation 2 was developed in thee 1970s and was the 1st generation wich uses a Microchannel Plate (MCP). During this time, due to drastic inovations in the semiconductor space, the first widespread integration of the PSU with the tube in a single, modern package appears. The Microchannel Plate (MCP) increased the gain imens.
Gain average around 20k.
Examples of Gen 2 devices
- GN-1 employed Gen 2 IIT upon release
Generation 3
The photocathode is made using gallium arsenide and the refined MCP technology is coated with an ion barrier film to prolong the tubes functional life. The downside of this ion film is that it somewhat restricts the amount of electrons that pass through it thereby detracting some of the intensification. The so called haloing-effect was also increased by this film, something that lessens the practical performance since it may obscure parts of what is being observed.
Subsequent development of the technology led to ”thin-film” tubes among other solutions to lessen the impact of the ion barrier on gain and resolution.
Gen 3 tubes are manufactured using different isotopes of phosphorous resulting in different green tints, white-to-grey/blue. A few tubes with red spectrum displays exist although they are very rare.
Gain averages between 30k to 50k.
Examples of Gen 3 devices
Filmless IIT
L3 Harris has developed and patented this specific development of MCP-related processes where the ion barrier film became obsolete and the actual channels in the plate have been increased in number by making each individual channel smaller in diameter. This has increased both Signal-to-Noise Ratio, Resolution and Gain to previously unparallelled measurement as well as attenuating halo-effect to near-negligible.
One particularity of L3 Filmless IIT is that they are exclusively manufactured with P45 isotope, commonly referred to as White Phosporous (or WP) in the contexts of both market and community.
Examples of Filmless devices
- DTNVS is sold with the option of Filmless tubes
