The human eye can see images which reflect light from violet to red in the electromagnetic color spectrum. Beyond the visible spectrum for humans is the light known as short-wave infrared, light. The human eye is unable to see that light. Short-wave infrared light is a term that actually encompasses all infrared light, but can be broken down into subcategories.
Infrared light actually falls into three classifications: near-infrared (near-IR or NIR), mid-infrared (mid-IR or MIR) and far-infrared (far-IR or FIR), also known as thermal-infrared. The difference between the three types of infrared light comes down to wavelengths. Near-IR, or NIR, has the shortest wavelength -- smaller than 1.5 microns -- and is closest to what we as humans can see as visible light. Far-IR, or FIR, is quite different. Thermal infrared wavelengths can be up to 30 microns and FIR is emitted from an object rather than reflected. In other words, FIR gives off thermal signatures while the other two types of infrared radiation do not.
The two main methods of night vision are thermal imaging and photon detection or image enhancing. Both are used regularly and both have their own advantages and drawbacks. Thermal imaging isn't quite as clear, but it is especially effective for picking up heat signatures. For instance, a soldier looking through a set of thermal imaging night-vision goggles would be able to spot an enemy that is hiding behind a bush or another object that gives off a colder signal. Unfortunately, the bright image could also be a friendly troop. Thermal imaging simply isn't clear enough to show that kind of detail.
Image enhancement on the other hand is very clear. Perhaps you've seen an example of imaging enhancement night vision on a news broadcast or military show. Oftentimes the picture is green, but other than that, the visual is clear as day. Image enhancing takes protons from ambient light and converts them into electrons. These electrons are then chemically and electrically converted into images that appear to be similar to watching an old black-and-white movie.
Next, let's take a look at how the automakers make use of night vision systems.