You’ve seen them in “Silence of the Lambs” and almost any film that involves military night operations and whether you’re nerdy or heroic you might have lusted for one of these engineering marvels. Well the good news is that not only are night visions coming down in price and going up in quality and ruggedness. Now is a great time to treat yourself to one of these grown up toys and this article will attempt to explain how night vision goggles work so you’ll know what to look for when buying one.
Humans have poor night vision compared to many other mammals and birds. That’s why we need a little assistance from technology. The human eye lacks a crucial component called the Tapetum Lucidum which is basically a piece of tissue that sends light through reflection to the retina located at the back of the eyeball.
If humans had a Tapetum Lucidum, we’d be able to discern a lot of movement images and in low light but we’d have trouble focusing. That’s because as the tapetum lucidum reflects light back, it causes a lot of interference in the image causing clarity to suffer. The thing is, our eyes were made for daytime use and that’s where nite vision goggles come to the rescue.
A broad category of products called NVD’s or night vision devices are made for military and civilian use. They can find their way into avionics equipment in smaller planes and helicopters to assist pilots keep their bearings at night and fly safely.
Night vision goggles or NVG’s are those incredible pieces of technology that have an image intensifier often with a set of magnification lenses to bring objects up close. They are categorized by generation in the following ways.
1. Gen 0 – First introduced in the 1930′s, gen 0 devices were used in the military on tanks and rifle scopes using photocathodes to intensify light.
2. Gen I – These were passive devices using ambient light such as moonlight instead of an infrared light source. Major drawback – they were big and heavy.
3. Gen II – With a light amplification of roughly 20,000X enabled these second generation devices to operate on moonless nights with clearer images.
4. Gen III – 30,000-50,000X light amplification, with clearer images and increased lifespan.
5. Gen III+ or Gen IV – Otherwise known as OMNI-VII, the newest generation of Night vision goggles offers some enhancements over the previous. Most notable is the presence of an automatic power supply which enables an OMNI-VII to adapt to changing light conditions. Hannibal Lechter would have had no problems having Jodie Foster for lunch had he opted for one of these.
So where are we headed?
Currently under experimentation are PNVGs or Panoramic Nite Vision Goggles which have a FOV (field of view) of 95 degrees instead of the usual 45 degree FOV. These devices use four image intensifier tubes instead of the usual two. Only US Air force pilots can get to use these currently but Hannibal would be delighted.