Image Intensification – This is the most common type of thermal night vision technology. It works, in the darkness, by capturing the tiny amount of available ambient light coming from the moon, stars and artificial sources. I2 also captures the lower end of the infrared light spectrum, that type of light is usually imperceptible to our eyes, but is present. The device 
captures these light sources, amplifies them thousands of times via an electronic “tube”, and projects the image on a viewing lens. The images appear a grey green color and there is a nice level of detail rendered with the latest, GEN III and GEN IV technology. You can even see through windows with I2. Note: There must be some light, I2 will not work in total darkness, such as in caves.
Thermal imaging – Thermal technology operates not by aggregating light; but by capturing the “heat” emitted by all object/persons. This “heat”, is literally the upper portion of the infrared light spectrum. Hot objects, like running machines, people and animals, emit more of this “light”/”heat” than cooler objects like rocks, trees or buildings. The image appear in gray-white or gray-black depending upon your preference, as the polarity can be adjusted so heat can either be shown black, or white. The thermal images are crisp enough to clearly distinguish facial features within 25-30 meters. Thermal imagers are commonly called thermal cameras, thermal sights, thermal monoculars or thermal binoculars. Note: Thermal imaging technology does not allow you to see through windows, or under water, because the “heat” is reflected back. In fact, you will see your body heated reflected back off the surface.
Fusion– Thermal imaging and Image Intensification technology have now been combined in single devices so both the infrared energy and the ambient light are captured. This allows the operator to now identify people and objects in almost all low-light/no-light environments. Now, thanks to fusion technology, Osama can’t hide in the total darkness of a cave, we can see him through windows, fog, etc. Fusion can be operated as an device, as a thermal imager, or in a combination mode. I recently got to try a $50,000 Fusion Goggle and I have to say,”wow, you can see someone’s soul”! There is even a mode in which there is an electric green wire frame outlining people. This is a great aid in targeting. You are the Predator! Sorry I cannot show you a fusion image.
This article comes from gunsamerica edit released