Part of the training involved looking at large table-top terrains to see how changing light levels and directions created optical illusions and other artifacts that could lead to accidents were the pilots not aware of them. Halos from light sources (streetlights etc.), spurious shadows, foreshortening of perspective, were all potential problems.
The goggles we used were pretty conventional: the kind that have been in use for two to three decades. They consist of two image intensifier tubes that amplify the effect of the small number of photons that fall on them, allowing you to see in a room that otherwise seems completely black. The problem is, that while you have them on, you can't see normally. If things suddenly get bright, you have to get them out of the way. Even worse, the old ones that I had could actually be damaged by bright light: we had to make sure to turn them off before the main light was turned on. Even with more recent models, care has to be taken in choosing which color of artificial light you choose to look at maps and things when necessary. Also, almost every NVG on the market the same problem of blocking your vision (and often your peripheral vision too, using cups around your eyes).
I have to admit, I was kind of amazed by this. As someone who has written about displays, including wearable displays, for many years, I couldn't understand why anyone would want to have their vision obscured by something that was supposed to be helping them see (especially in a kill or be killed situation). Also, as someone who hopes to see all this money flowing into military technology eventually trickle down to more consumer-related products, I felt sure that this blindfold effect was bound to be a stumbling block. Surely there was some nice technology (some nice micro-mechanical laser scanner, perhaps) that could give you an image inside some semi-transparent glasses?
I asked around, a lot. Most of the people I talked to said they had heard of such a thing, and gave me various leads to follow up that went nowhere. But when I talked to military people, no-one seemed very interested. Lots were doing sensor fusion (where several sensors were combined into one image), but the view was still not transparent. Finally I found a company at the Night Vision 2006 conference/exhibition I went to last week, STS Technology, that (apparently uniquely) makes a product that's exactly what I had in mind. Some folded optics combined some night vision sensors and a digital display (for maps and other information) into a single transparent eyepiece with a direct view of the world.
OK, so I'm not a pilot, a soldier, or a marine, but to me, the advantages of these NVGs were completely clear (no pun intended) with one simple experiment. The guy in charge had me look at him while wearing the goggles in the conference darkroom. Then he turned on the light. The night vision view of him turned seamlessly into a direct view of him through the eye piece. Ideal if, for instance, a bomb goes off (at night) or the lights go off (leaving you in the dark). A combined thermal imager can also help you to see through fog, smoke, or other particulates should that become necessary. Even better, peripheral vision is left intact (no cups or shields are needed around the eye), so there is only a 7° cone on each side of the head that is blocked.
No, I'm not on commission, but sometimes I'm intrigued by how conservative buyers of technology can be. Maybe there's some huge disadvantage of the technology that I'm missing... but if so, it's really not obvious.
Photo
Trying night vision goggles for the first time at RAF Henlow, looking at an artificial terrain designed to prevent overconfidence in pilots by showing the weaknesses in the technology.
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