Submersible Night Vision
L-3 EOS (Electro-Optical Systems) offers a monocular I² night vision system based on the military AN/PVS-18 model, called the M983. Cut a pair of binoculars in half lengthwise, and you've got an idea of the size and shape of the device. The M983 was produced for use by U.S. Navy SEALs, and will function underwater up to 20 meters for two hours. It runs on a single AA battery, and weighs 350 grams-about three-quarters of a pound.
This is a highly versatile piece of gear. It incorporates an IR illuminator for situations when there just isn't enough ambient light to provide the desired level of detail. It has a field of view of 40 degrees with mounts available for use as a handheld pocket scope, left or right mounting on a helmet, as a gun sight, or for photographic use when mated to an SLR camera.
L-3 EOS supplies five grades of I² tubes, and any one of them can be housed in the M983. The tubes are designated Alpha, Gamma, Delta, Omega, and Infinity, with specs of 45 to 64 lp/mm.
Best of Both Worlds
ITT Night Vision recently rolled out its Dual Sensor Night Vision Goggle (DSNVG). The DSNVG combines an I² tube and IR microbolometer into one monocular device. It uses a separate battery pack and can be either mounted on a helmet or handheld.
There is a clear advantage to a device that combines I² and IR technologies. Where I² is useless in total darkness, IR finds warm spots regardless of light conditions. In an environment that has too many warm targets to discriminate the one you're interested in, the I² scope allows you to identify him visually. And best of all, the thermal image can be overlaid onto the I² view, so you see your target and his surroundings. The entire package weighs less than two pounds.
I² or IR?
The resolution of thermal imagers lags considerably behind image intensifiers and visible light optics. Where an I² image would permit recognition of facial features and reading of large print, a thermal image from the same range is going to look more like a blob, or maybe several blobs. Still, the I² gear requires some ambient light, while the thermal imager needs none at all. If you combine the two technologies, which is now possible, you'll own the night and anyone wandering around in it.
Tim Dees is a retired police officer and the former editor of two major law enforcement Websites who writes and consults on technology applications in criminal justice. He can be reached via firstname.lastname@example.org.
Night Vision and Thermal Imaging Manufacturers:
American Technologies Network
ITT Night Vision
L-3 Electro-Optical Systems
Night Optics USA