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Night Vision Equipment: The Illuminating Work of NRC Aerospace The illuminating work of NRC aerospace |
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| Written by Blair Watson | |
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Flying at night has always been challenging for pilots because of
reduced visual information compared to what they see during daytime VFR
flights. Military, police, search-and-rescue, and other types of
rotary-wing operations sometimes occur over areas where there is
little, if any, ambient light. Recognizing these challenges and
developing night vision systems for pilots has been part of the work of
the National Research Council of Canada Institute for Aerospace
Research for more than a decade. NRC Aerospace, as it is known, is Canada’s national aerospace research organization. It is funded by taxpayers’ dollars through the Ministry of Industry. NRC Aerospace, which has a research institute in Ottawa and a technology centre in Montreal, employs more than 300 professional, technical and support staff in five laboratories. A team of engineers, neuroscientists, psychologists and test pilots has worked with night vision technology (NVT) since the mid-1990s. The research team has completed more than 500 hours of flight testing involving night vision goggles (NVGs) and other vision-enhancing systems for pilots. The systems allow objects illuminated by a relatively faint light source to be seen by the user. Because NVT alters the way pilots see, perceive and process information, developing NVGs has involved specialized research and testing, aircraft and helmet modifications, pilot training, and more.
NRC Aerospace has two helicopters used for flight testing, a Bell 205 and 412, which have been modified to fly-by-wire for the purpose of adjusting their handling characteristics. For example, in the early stages of testing a particular NVT it is important that the helicopter be easier to fly because the pilot needs to focus on adjusting to the new night vision equipment. As the pilot becomes more proficient with it, the fly-by-wire helicopter can be adjusted accordingly. The history of night vision systems dates back to the Second World War. During the Vietnam conflict, the U.S. military introduced night vision devices (NVDs), which had an image intensifier that amplified ambient light about 1,000 times. Used in army helicopters and other applications, NVDs of 40 years ago were bulky and required moonlight to function properly. Today, night vision equipment requires comparatively little light; illumination from a dim star is adequate. The light amplification of third-generation NVGs is approximately 30,000 to 50,000 times. NVGs operate in the near-infrared wavelength band of about one micrometre. By comparison, the diameter of the average human hair is 50 micrometres. Our eyes require a light wavelength of 0.4 to 0.7 micrometres to see. Unlike passive infrared systems, which detect heat radiation and can operate in complete darkness, NVGs require some ambient light. Intensifier tubes in NVGs—which look like binoculars—operate on the photoelectric effect. As photons from an object illuminated by starlight, for example, collide with a detector plate inside each tube, the chemical coating on the plate emits electrons, which are then amplified by an electrical charge into a cascade of electrons that light up a phosphor screen. The colour of what the user sees is monochromatic neon green.
NVGs are attached to the front of a pilot’s helmet and positioned about one centimetre in front of their eyes. To see the helicopter’s instruments and switches, the pilot tips his head back and looks below the goggles. A battery pack on the back of the helmet provides power to the NVGs and acts as a counterbalance to reduce neck strain. In terms of the pilot’s field of vision, one NRC Aerospace test pilot described the experience of using NVGs as looking through two soup cans with the ends removed. The latest generation of NVT is Omnibus-VII. Unlike third-generation night vision equipment, OMNI-VII devices have an automatic gated power supply that regulates the photocathode voltage, allowing the device to instantaneously adapt to changing light conditions. Because OMNI-VII NVGs have a thinned or removed ion barrier in each tube compared to previous generations of NVT, about 40 per cent less light is required. Also, there is less image ‘noise’. The disadvantage of OMNI-VII technology, however, is a decrease in tube life of about 25 per cent compared to third-generation equipment. Canadian Forces is the country’s largest user of NVT. A Sept. 15, 2005 press release said: “The air force currently uses night vision technology in the CH-146 Griffon and CH-149 Cormorant fleets; however, the new night vision goggles [OMNI-VI technology] and the associated aircraft equipment will enhance operational performance.” The release adds: “The CH-124 Sea King will also gain night vision goggle capability allowing the maritime helicopter community to obtain training that will be directly transferable to the new CH-148 Cyclone helicopter fleet.
“Night vision equipment will enable downed aircrew to move to a rendezvous point at night with the ability to carefully observe their surroundings. This capability will be achieved through the use of a compact lightweight monocular [a one-tube unit] carried in the aircrew survival vest. “Search-and-rescue missions frequently occur at night in mountainous terrain and over water and in most cases timing is critical. The new night vision capability will greatly increase safety and capability when undertaking these challenging missions.” The Forces’ Omnibus Night Vision Capability Project will provide “helmet-mounted night vision goggles and night vision aids to all tactical and search-and-rescue fleets. This project will ensure commonality of night vision equipment, reduce life cycle cost, simplify training and reduce procurement time.” NRC Aerospace has done NVG work not only for Canadian Forces, but also non-military helicopter operators such as the Ministry of Natural Resources (MNR) in Ontario. NVGs have applications for the ministry’s Aviation and Forest Fire Management Program (AFFMP) such as detection of forest fires, extractions of firefighters in emergency situations, mapping of active fires, and enforcement patrols. In conjunction with NRC Aerospace, MNR-AFFMP has been evaluating NVT since 2005. In June 2007, MNR received Transport Canada approval and operations specification to allow the integration and use of the technology in the ministry’s aircraft. The NVGs used are military grade and made by US-based ITT Industries, one of the world’s largest manufacturers of night vision equipment. Cockpit and external lighting modifications were required involving two MNR helicopters, an AS350 and EC130.
All Canadian helicopter operators using NVGs must provide specialized training for pilots, which NRC Aerospace has helped to develop. There are two National Research Council test pilots and two Transport Canada NVG certification pilots. Training consists of ground school and flight training; instructor pilots have extensive military or police NVG experience. The effectiveness of NVGs was proven last summer when an AFFMP aircrew detected, from a distance of 14 kilometres, a small (0.1-hectare) fire started by lightning. Enhanced nighttime fire detection should result in fewer hectares of burned forests. NRC Aerospace continues to develop and test systems utilizing the latest NVT. For example, a head-tracking system has been designed consisting of a low-power laser mounted on the aft cockpit and diodes on the back of the pilot’s helmet. Like a laser scanner in a grocery store, the laser ‘scans’ the helmet. When the test pilot turns his head, the movement is ‘captured’ and can be duplicated in a motorized mount containing a camera or sensor. Future ‘illuminating’ work of NRC Aerospace will involve panoramic night vision goggles, digital night vision systems, and equipment that combines image intensification with thermal imaging. NRC Aerospace professionals will continue to develop systems that enhance the ability of helicopter pilots to fly at night. |
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