FLY BY NIGHT – The World of Airborne Night Vision
By David Maxwell
During the Second World War, aircrew on night operations were encouraged to eat carrots to improve their night-vision. It was, of course, folk-lore. Today, aircrew have image-intensified Night-Vision Goggles (NVGs) and thermal imaging Forward-Looking InfraRed (FLIR) to allow them to see in the dark. For Unmanned Aerial Vehicles (UAVs), these sensors are packaged into a sensor turret, sometimes referred to as a gimbal.
The current purpose of night vision for aerial platforms, be they fixed-wing, helicopters or UAVs, is two-fold: to allow safe navigation and situational awareness (SA), usually at low-level; and, then, to identify targets that have to be attacked. When first introduced, such systems were stand-alone, just producing one element of the requirement. The information was brought together and actioned-upon by the pilot’s brain alone.
Now, the night vision elements are integrated together with image processors, laser rangefinders, laser spot trackers and laser illuminators to offer an integrated targeting system. The pilot, by the way, still has to “press the tit” and activate weapons launch or firing! So much for the basic theory. How is it put into practise?
Goggles and helmets
In the same way soldiers wear NVGs on their helmets, so too can aircrew. Known as Aviators Night VIsion Systems (ANVIS), they are the one element that has not yet been ‘digitised’ into a fully integrated system, although it is coming. The first article of this series, explained the principles and development of the NVG and its core element, the image intensification (II) tube. The standard, since the mid-1980s, has been the 18mm-diameter third generation (Gen III) tube, with those manufactured today having twice the performance of the original tubes yet being significantly cheaper to procure.
After the US Army’s Omnibus (Omni) V procurement, looking for an II tube that removed the ion-barrier film used to protect the microchannel plate, thus extending tube life, Northrop Grumman (now L-3 EOS) seemed successful. However, ITT Night Vision fought back, produced a tube, which reduced the thickness of this ion-barrier film, which they called the ‘Pinnacle’ tube. This eventually won the day, as the US Army increased ITT’s share of the Omni V options from 40% to 100% (with first deliveries in February 2001). The Pinnacle (thin-film) tube’s effectiveness was confirmed by the Omni VI contract award in May 2002, worth some US$450 million, which saw ITT winning 100% of the aviation element and 60% (the maximum allowable percentage) for ground forces.
The standard US aviator’s NVGs, initially developed for the US services but sold to many of its allies, are the AN/AVS-6 and AN/AVS-9 ANVIS systems. Produced by both ITT and Northrop Grumman in the past, they offer a 40 degree field-of-view (FoV) and the ability to use Gen III Pinnacle tubes. They look very much like a soldier’s AN/PVS-7 series goggle, but with a complicated helmet mount. The goggles themselves weigh 590g and 550g, respectively, but the weight of the mount on the helmet increases system weight. As with a soldier system, getting balance on the helmet is an important element. Thus developments that reduce weight (and, hence, neck strain for the pilot) are pursued with vigour, especially as the g-force pilots can experience in aerial manoeuvres, whether fixed-wing or helicopter, increase the strain.
Of course, NVG development is not confined to the United States and the European and Israel industries have produced their own products, such as the UK’s BAE Systems Nightbird, the French Sagem Défense Sécurité CN2H-series, the Helimun series from OIP Sensor Systems of the Netherlands, the PNL-3 from PCO of Poland and the Elbit Systems ANVIS/HUD system from Israel. The latter is bringing Head-Up Display (HUD) data into the NVG FoV, to ease pilot workload.
While accepting each product has its unique featu