Dispelling the Gen 4 Night Vision Myth

gen 4 myth scope

There has been a lot of talk about Gen 4 night vision in recent years.

Rapid technological developments, and false starts have given rise to some substantial misconceptions about Gen 4 night vision. Thankfully, Night Vision Australia is here to help clear the air.

American Troop with Night Vision Scope

There are four Generations of night vision. However, they are numbered from Gen 0 to Gen 3. The first generation of night optics were developed during the Second World War. The first era of development was largely plagued with units that were impractical thanks to bulky power supplies and cumbersome illuminators. The designation of ‘generations’ begins around this time, largely credited to the US Army.

In the late 90’s the US Army did make a claim to the creation of Gen 4 technology. Night vision technicians removed the ion barrier film, creating a “filmless” tube. The ion barrier was introduced during the leap from Gen 2 to Gen 3. It was designed to protect the micro-channel plate (the device responsible for light amplification) from the gallium arsenide that was also added to improve light sensitivity.

They claimed this was the pivotal next step in the development of night vision technology. This new advancement was designed to reduce halos while increasing sensitivity, signal-to-noise ratio and resolution. In layman’s terms, it was a huge jump for overall improved performance.Machine Gunner

For a while performance was improved, and it seemed that Gen 4 had indeed been achieved. However the lack of an ion barrier in Gen 4 tubes eventually led to high failure rates. Ultimately the U.S. Army recanted the existence of the Gen 4 definition.

The high failure rates of these tubes spurred the ITT Corporation to improve upon existing technology by creating a “thin-filmed” tube. By reducing the thickness of the ion barrier, ITT was able to maintain the reliability of Gen 3 while still delivering on the US Army’s performance requirements intended for next generation devices. This resulted in the production of the Gen 3 thin-filmed tube, now considered the highest performing night vision tube available.

Pilot with Night Vision

Pilot with Night Vision 2

So as it stands Generation 4 is still yet ahead of us. With formidable leaps forward in technological development and the growing demand for high performance night optics, the next generational leap is only one crazy innovation away.

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Comments (1)

There is a significant amount of misinformation regarding the use of “Generations” to describe night vision image intensifier tubes (e.g., Gen 0, Gen I, Gen II, Gen III and Gen +) especially when addressing their capabilities and limitations. The US Department of Defense (DoD) de-emphasized the use of the term “generation” as a determinant factor of a tube’s performance. The term generation in today’s environment only refers to the material used in the photocathode, i.e., Multi-Alkaline for Gen II, or Gallium Arsenide for Gen III. Gen III makes use of ion barriers, however it’s because of the use of Gallium Arsenide – not because it’s a massive technological advancement in tube performance. What that means is that a Gen III tube is not necessarily “better” than a Gen II. The advanced Multi-Alkaline tubes of 2018 are vastly improved in performance so that today very little comparison can be made between the two generations, which in turn, has affected the way the military grades tubes. Image intensifier tubes are now graded by performance in their Signal to Noise Ratio (SNR), Resolution, Halo, and Gain, with Figure of Merit (FOM) being the main differentiator. FOM is calculated by multiplying the SNR by Resolution. FOMs greater than 1600 are restricted for export from the USA while FOMs exceeding 1600 or higher are generally restricted to the USA and/or police/military only. With regard to the military specifications in each category, the modern Gallium Arsenide or Multi-Alkaline tube meets or exceeds the current requirements for FOM, SNR, resolution, and gain required by the DoD. In common usage, a night vision device said to be “a FOM 1600 system” will have a tube performance less than or equal to 1600.

Another item addressed is the service life of a tube. Stating that a Gen III tube has a longer service life than a Gen II tube is no longer the case with modern Multi-Alkaline (“Gen II”) image intensifier tubes. DoD requirements are for 10,000 hours of service life for a night vision tube and modern Multi-Alkaline tubes meet this requirement.

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