The technology behind night vision equipment is becoming very advanced. The degree of technology used to make them depends on who they are being made for. There are two sets of customers for this equipment, those being the regular consumer, and law enforcement as well as military personnel.
The military version of this equipment is now in it's fourth generation and is going to be more costly because it is the most advanced. The consumer models are less costly, but it's not because of the quality. It's simply because of the age of the technology used.
It's still relevant, just not as advanced. With military models now being in the fourth generation and costing as much as $6,000 per unit, they're a little out of reach for the average consumer. But you can find third generation cheap night vision equipment models for as little as $1,000 a piece or sometimes even less, which is a very good deal.
As well as two different types of consumers for night vision goggles, you have two different types of night vision goggles themselves. Depending on why you want night vision equipment, will help dictate what type you buy.
You have what are called passive goggles and active goggles. A good deal of thought and science has been put into making this equipment, and whether you're purchasing a passive or active unit, you can't help but be impressed by it all.
Electo-optical imaging is at the heart of it all as it detects nearly all energy sources' electrical impulses and intensifies them into an image that is then picked up by the users' optical nerves. Which are themselves electrical impulses.
A passive set of night vision equipment is best described as general vision. They pick up any type of light within it's field of vision, magnify it and set it against a green backdrop. Anything you see from that point on that isn't green is an object.
If the object moves then it is either a person or an animal, depending on what shape you see. The reason the engineers of this equipment chose green as a backdrop is because it's been proven to be easier on the users eyes when they take the goggles back off and have to readjust their vision to a normal field of vision.
That, and the colors used to discern objects, stand out more when transposed onto a “screen of green”. Active vision is a more precise method used in night vision equipment. Infrared light is projected outward from the unit, projecting an image to the user by the light that it sent back that was picked up by the infrared light.
This happens in a split second and is widely used in video cameras, both personal and professional. The newer generation of this technology is the best yet at being able to pick up and magnify back to the user exact replicas of objects or people in the night.
There are night vision goggles though that are a combination of both methods and are primarily made for military and law enforcement personnel.