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 the 1970s and was the first generation using 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.
Generation 2 IIT are produced mainly with either green or white phosphor screens.
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 Aluminium oxide layer called ion barrier film to prolong the tubes functional life by preventing the occasionally released ion to damage the MCP, a process called ion-poisoning which drastically dimishes the plates functional lifespan. 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. Since the beginnings of thin-film IIT it has become so commonplace that instead of being singled out as having thin ion barrier film the earlier image intensifiers are nowadays referred to as ”thick-film” instead.
Gen 3 tubes are manufactured in both green and white phosphor screen versions although some manufacturers have equipped their IITs with other monochromatic and in the case of Adams Industries a bichromatic screen.
Gain averages between 30k to 50k.
Examples of Gen 3 devices
Filmless IIT
Manufacturer L3Harris stands out as the sole producer of Filmless/Unfilmed (term used interchangeably) tubes due to having patented the process. See relevant section on the manufacturers page for further information.
Generation 4
Formats
- Mx9916 (Fat Anvis)
- MX-10130
- MX-10160 / Small Anvis / 37mm / 18mm
- MX-11769
- SwaP (16mm)
