Night vision and thermal imaging are very different technologies. Let’s explore both:
Night Vision devices take in small amounts of visible light, amplify it greatly, and project that on a display to provide the user with a clearer picture in low light situations. Night vision devices need some type of light in order to work. This light can be as subtle as moonlight or as expansive as an infrared lamp. If there is absolutely no light, your night vision device will be useless.
Night vision devices often offer greater image clarity than thermal devices. However they still have the same challenges that the human eye faces. For example, if objects are camouflaged, they will not be any easier to see with night vision. This is a situation where thermal imaging would be a good device to use. The thermal devices will be able to detect camouflaged objects just fine. Another challenge is that night vision will not work in daylight or in lighted rooms. Night vision devices are also not able to see through obscurants in the air such as fog, dust or sand.
Thermal technology operates differently than night vision. It does not aggregate light. Instead thermal imaging operates off of heat and captures the “heat” that is emitted by all objects, including people and animals. Everything gives off thermal energy/heat, even ice. The hotter an object is, the more thermal energy is emitted. The emitted thermal energy from an object is called a “heat signature”. The thermal imaging devices detect the temperature differences of objects and translate them into image detail.
Everything we encounter in our day-to-day lives gives off thermal energy, even ice. The hotter something is the more thermal energy it emits. This emitted thermal energy is called a “heat signature.” When two objects next to one another have even subtly different heat signatures, they show up quite clearly to a FLIR regardless of lighting conditions.
Unlike night vision, thermal imaging works in both day and night, in light or in complete darkness. It also allows you to see through obscurants such as fog, dust, smoke or sand.
Thermal imaging devices also have the ability to track residual heat (warm spot left behind). For example, the device will be able to see handprints or footprints that are left behind from a person or animal.
In conclusion, thermal imaging detects the thermal or infrared energy emitted by various objects and turns that into an image. Night vision operates very similar to the human eye, and requires much less light to function.