NIGHT VISION FOR THE INFANTRY SOLDIER
By David Maxwell
The first in our series ‘Owning the Night’
If current operations in Afghanistan and Iraq have proved anything, it is that in today’s asymmetric form of counter-insurgency warfare, every soldier on the ground must be capable of operating by night as well as by day. As a result, a night-vision device (NVD) of some description – usually a night-vision goggle (NVG) – is no longer the luxury item issued one per platoon. It has become the “must have” accessory any effective soldier cannot afford to be without.
The yardstick NVG today, against which performance is measured, must be the US Army’s AN/PVS-7D NVG fitted with a second generation (Gen II) image intensifier (II) tube. Manufactured by both the former-Litton Electro-Optical Systems (acquired by Northrop Grumman in 2001) and ITT Industries’ Night Vision division (each company bidding for a share of the annual production requirement), both companies also produce the II tubes, without which the NVG is inoperable.
Despite the rapid improvements of thermal imaging (TI) technology and the vast reduction in size and weight of thermal detectors (to which we shall return), the II-powered NVD remains vital. Despite being declared on the verge of obsolescence several times, the II tube continues to be developed. Why? Compared with TI devices, they remain comparatively less expensive, lighter and more flexible in application by a soldier on the ground.
All a soldier expects from an NVD is “to be able to see in the dark”. In the majority of cases, that means an “outdoor” dark, where most of the time there is always ambient light (moonlight and starlight principally) available. The II tube is the heart of the NVD, as it gathers and focuses this ambient light and converts it to an image.
Our yardstick AN/PVS-7 NVG equipped with a Gen II tube can see a vehicle-sized target out to a distance of 170-180m in overcast starlight. Whatever the technology in the tube may use, the more light there is, the better the range. The better the tube technology, then the better the performance in lower light conditions and, despite predictions to the contrary, image intensification technology has refused to die.
It is generally recognised that the US Army’s Night Vision and Electronic Sensors Directorate (NVESD), based at Fort Belvoir, Virginia, part of the Research, Development and Engineering Command (RDECOM), has led the development of night vision devices (encompassing weapon sights and hand-held observation devices as well as NVGs). As lead customer for such products, it considers itself the authority for designation the technology levels applied to night vision, be it II or TI (also referred to as IR – infrared) systems.
The NVSED (and its predecessors) has been responsible for many of the advances in this field, either sponsored or with direct development. The US Army (and other US and allied services) has proven a vast market for such products. More than 150,000 of the AN/PVS-7 series of NVGs have been fielded. The US Army is the lead customer for NVGs in the world, with ITT Industries Night Vision (Roanoke, Virginia) and Northrop Grumman (Rolling Meadows, Illinois) competing to develop technology and products.
As the key to NVD operation, the 18mm II tube has evolved over the years with the differing standards being assigned “generations”, which represent a manufacturing standard rather than visual performance. However, the US government has imposed a restriction on the export of US-manufactured II tubes, based on what is referred to as the Figure of Merit, which is calculated by multiplying the resolution (line pairs per millimetre) by the signal-to-noise ratio (SNR).
II tube development
The current standard of II tubes is categorised as Gen III. Since the mid-1980s, when the US Army initiated the Omnibus (Omni) procurements for tubes and the sensors that used them, large production volumes have been gene